Patent Description:
Spindle units capable of securing a spindle of a machine tool are known.

A known rotary shaft locking device in accordance with the preamble of claim <NUM> is disclosed in <CIT>. The spindle unit disclosed in <CIT> secures a spindle by the engagement between a coupling member located behind a front end wall and a coupling member located on a flange on an outer surface of the spindle. The spindle unit disclosed in <CIT> includes a second fluid pressure means, which is capable of pressing a bearing case rearward, and a third fluid pressure means, which is capable of pressing the bearing case forward. In the spindle unit disclosed in <CIT>, the levels of the forward pressure that acts on the bearing case and the rearward pressure that acts on the bearing case are the same but the forward pressure and the rearward pressure act in opposite directions. Thus, in securing the spindle, no load is applied to the bearing.

It is the object of the present invention to provide a rotary shaft locking device that has a reduced load acting on balls of an angular contact ball bearing in the state in which the rotation of a rotary shaft is locked.

The object of the present invention is achieved by a rotary shaft locking device having the features of claim <NUM>.

For example, a machining head comprising, inter alia, the rotary shaft locking device according to the present invention is defined in claim <NUM>, and a multi-tasking machine comprising, inter alia, such a machining head is defined in claim <NUM>.

According to an advantage of the present invention, a rotary shaft locking device includes a rotary shaft, a first angular contact ball bearing, a support member, and a drive unit. The rotary shaft includes a mounting portion on which a tool will be mounted and a first contact surface. The rotary shaft is rotatable about a first axis. The first angular contact ball bearing includes an inner ring supported by the rotary shaft, an outer ring, and a plurality of balls disposed between the inner ring and the outer ring. The support member includes a second contact surface configured to come into contact with the first contact surface to lock rotation of the rotary shaft. The support member rotatably supports the rotary shaft through the first angular contact ball bearing. The drive unit is configured to move the rotary shaft and the inner ring relative to the support member and the outer ring in a first direction parallel to the first axis so that the first contact surface comes into contact with the second contact surface and so that precompression that acts on the plurality of balls is reduced.

According to another advantage of the present invention, a machining head includes a first rotary drive unit, a housing, and a rotary shaft locking device. The first rotary drive unit is configured to rotate a rotary shaft about a first axis. The housing surrounds the rotary shaft. The rotary shaft locking device includes the rotary shaft, a first angular contact ball bearing, a support member, and a drive unit. The rotary shaft includes a mounting portion on which a tool will be mounted and a first contact surface. The rotary shaft is rotatable about the first axis. The first angular contact ball bearing includes an inner ring supported by the rotary shaft, an outer ring, and a plurality of balls disposed between the inner ring and the outer ring. The support member includes a second contact surface configured to come into contact with the first contact surface to lock rotation of the rotary shaft. The support member rotatably supports the rotary shaft through the first angular contact ball bearing. The drive unit is configured to move the rotary shaft and the inner ring relative to the support member and the outer ring in a first direction parallel to the first axis so that the first contact surface comes into contact with the second contact surface and so that precompression that acts on the plurality of balls is reduced.

According to a further advantage of the present invention, a multi-tasking machine includes a machining head, a workpiece holding device, a machining head drive unit, and a controller. The machining head includes a rotary shaft locking device, a first rotary drive unit configured to rotate a rotary shaft about a first axis, and a housing surrounding the rotary shaft. The workpiece holding device is configured to hold a workpiece. The machining head drive unit is configured to move the machining head relative to the workpiece holding device. The rotary shaft locking device includes the rotary shaft, a first angular contact ball bearing, a support member, and a drive unit. The rotary shaft includes a mounting portion on which a tool will be mounted and a first contact surface. The rotary shaft is rotatable about the first axis. The first angular contact ball bearing includes an inner ring supported by the rotary shaft, an outer ring, and a plurality of balls disposed between the inner ring and the outer ring. The support member includes a second contact surface configured to come into contact with the first contact surface to lock rotation of the rotary shaft. The support member rotatably supports the rotary shaft through the first angular contact ball bearing. The drive unit is configured to move the rotary shaft and the inner ring relative to the support member and the outer ring in a first direction parallel to the first axis. The workpiece holding device includes a workpiece holder, a second support member, and a second rotary drive unit. The workpiece holder is configured to hold a workpiece. The second support member is configured to support the workpiece holder to be rotatable about a second axis. The second rotary drive unit is configured to rotate the workpiece holder about the second axis. In response to the controller transmitting a first control signal to the machining head drive unit, the machining head drive unit moves the machining head relative to the workpiece holding device. In response to the controller transmitting a second control signal to the first rotary drive unit, the first rotary drive unit rotates the rotary shaft about the first axis. In response to the controller transmitting a third control signal to the second rotary drive unit, the second rotary drive unit rotates the workpiece holder about the second axis. In response to the controller transmitting a fourth control signal to the drive unit, the drive unit moves the rotary shaft and the inner ring relative to the support member and the outer ring in the first direction so that the first contact surface comes into contact with the second contact surface and so that precompression that acts on the plurality of balls is reduced.

A machining head <NUM>, a rotary shaft locking device <NUM>, and a multi-tasking machine <NUM> according to some embodiments will hereafter be described with reference to the drawings. In the following description of the embodiments, identical reference numerals are given to portions and members having identical functions, and descriptions of the portions and members with the identical reference numerals that are deemed redundant will be omitted.

A machining head 1A and a rotary shaft locking device 10A according to a first embodiment will be described with reference to <FIG>. <FIG> and <FIG> are schematic cross-sectional views of part of the machining head 1A according to the first embodiment. Note that <FIG> shows a state in which a rotary shaft <NUM> is rotatable about a first axis AX1, and <FIG> shows a state in which the rotation of the rotary shaft <NUM> is locked. <FIG> is an enlarged schematic cross-sectional view of part of a first angular contact ball bearing <NUM> and the surrounding section. <FIG> is a schematic cross-sectional view of the first angular contact ball bearing <NUM> according to an embodiment. <FIG> is a schematic cross-sectional view of the machining head 1A according to the first embodiment. <FIG> is an enlarged view of the section indicated by circle A1 drawn with an alternate long and short dash line in <FIG>. <FIG> is an enlarged view of the section indicated by circle A2 drawn with an alternate long and short dash line in <FIG>. <FIG> is a schematic cross-sectional view of the machining head 1A according to the first embodiment. <FIG> is an enlarged view of the section indicated by circle A3 drawn with an alternate long and short dash line in <FIG>. Note that <FIG> and <FIG> show a state in which the rotary shaft <NUM> is rotatable about the first axis AX1, and <FIG> and <FIG> show a state in which the rotation of the rotary shaft <NUM> is locked.

The machining head 1A according to the first embodiment includes the rotary shaft locking device 10A, which is capable of locking the rotation of the rotary shaft <NUM>, and a housing H, which surrounds the rotary shaft <NUM>. The rotary shaft <NUM> is rotated by a first rotary drive unit <NUM> (see <FIG> if necessary) of the machining head 1A. The rotation of the rotary shaft <NUM> is locked by bringing a first contact surface C1 of the rotary shaft <NUM> into contact with a second contact surface C2 of a support member <NUM> (see <FIG> or <FIG> if necessary).

Subsequently, the rotary shaft locking device 10A will be described.

According to the embodiment illustrated in <FIG>, the rotary shaft locking device 10A includes the rotary shaft <NUM>, the first angular contact ball bearing <NUM>, the support member <NUM>, and a drive unit <NUM>.

The rotary shaft <NUM> includes a mounting portion <NUM> on which a tool (such as a milling tool or a lathe tool) will be mounted and the first contact surface C1, which is capable of coming into contact with the second contact surface C2 of the support member <NUM>.

The rotary shaft <NUM> is rotatable about the first axis AX1. In the embodiment illustrated in <FIG>, the rotary shaft <NUM> includes a rotary shaft body <NUM> and the mounting portion <NUM>, which is located inside the rotary shaft body <NUM>. In the embodiment illustrated in <FIG>, the rotary shaft <NUM> is an assembly of a plurality of components.

The rotary shaft <NUM> includes a distal end portion <NUM> and a rear end portion. In the embodiment illustrated in <FIG>, the above-mentioned mounting portion <NUM> is located on the distal end portion <NUM> of the rotary shaft <NUM>. The first angular contact ball bearing <NUM> is also located on the distal end portion <NUM> of the rotary shaft <NUM>.

The first angular contact ball bearing <NUM> includes an inner ring <NUM>, an outer ring <NUM>, and a plurality of balls <NUM> (in other words, a first ball group).

In a state in which the balls <NUM> receive precompression from the inner ring <NUM> and the outer ring <NUM>, a straight line that connects a contact point E1 between the inner ring <NUM> and each ball <NUM> and a contact point E2 between the outer ring <NUM> and the ball <NUM> is inclined with respect to a radial direction DR3 of the first angular contact ball bearing <NUM>. In the embodiment illustrated in <FIG>, the contact point E1 is located forward of the contact point E2. It should be noted that, in the present description, "forward" means a direction moving from the rear end of the rotary shaft <NUM> towards the distal end of the rotary shaft <NUM>. Additionally, in the present description, "rearward" means a direction moving from the distal end of the rotary shaft <NUM> towards the rear end of the rotary shaft <NUM>.

The inner ring <NUM> is supported by the rotary shaft <NUM>. More specifically, the inner ring <NUM> is secured to the rotary shaft <NUM>. In the embodiment illustrated in <FIG>, the inner ring <NUM> is located around the distal end portion <NUM> of the rotary shaft <NUM>.

The outer ring <NUM> is supported by the support member <NUM>. More specifically, the outer ring <NUM> is secured to the support member <NUM>.

The plurality of balls <NUM> (in other words, the first ball group) are located between the inner ring <NUM> and the outer ring <NUM>.

In the embodiment illustrated in <FIG>, the inner ring <NUM> is movable relative to the outer ring <NUM> in the direction parallel to the first axis AX1. When the inner ring <NUM> moves relative to the outer ring <NUM> in the direction parallel to the first axis AX1, the precompression that acts on the plurality of balls <NUM> (in other words, the precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM>) changes.

For example, in the embodiment illustrated in <FIG>, when the inner ring <NUM> moves relative to the outer ring <NUM> in a first direction DR1, which is parallel to the first axis AX1, the precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM> is reduced (see <FIG>). In the embodiment illustrated in <FIG>, when the inner ring <NUM> moves relative to the outer ring <NUM> in a second direction DR2, which is opposite the first direction DR1, the precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM> is increased.

The first angular contact ball bearing <NUM> may include a plurality of angular contact ball bearing assemblies <NUM>. Each angular contact ball bearing assembly <NUM> includes the inner ring <NUM>, the outer ring <NUM>, and the plurality of balls <NUM>. In the embodiment illustrated in <FIG>, the plurality of angular contact ball bearing assemblies <NUM> are located one next to the other in the direction parallel to the first direction DR1. In the embodiment illustrated in <FIG>, the first angular contact ball bearing <NUM> is constituted by the plurality of angular contact ball bearing assemblies <NUM> located one next to the other in the direction parallel to the first direction DR1. Alternatively, the first angular contact ball bearing <NUM> may include one angular contact ball bearing assembly <NUM>.

The support member <NUM> includes the second contact surface C2, which is capable of coming into contact with the first contact surface C1. When the first contact surface C1 of the rotary shaft <NUM> comes into contact with the second contact surface C2 of the support member <NUM>, the rotation of the rotary shaft <NUM> about the first axis AX1 is locked (see <FIG>). When the first contact surface C1 and the second contact surface C2 separate from each other, the rotation of the rotary shaft <NUM> about the first axis AX1 is permitted (see <FIG>).

The support member <NUM> rotatably supports the rotary shaft <NUM> through the first angular contact ball bearing <NUM>. In the embodiment illustrated in <FIG>, the support member <NUM> includes a first end wall <NUM>, which is an end wall on the front side, a first block <NUM>, which supports the first angular contact ball bearing <NUM>, and a side wall <NUM>, which covers at least a middle portion <NUM> of the rotary shaft <NUM>. In the embodiment illustrated in <FIG>, the support member <NUM> is an assembly of a plurality of components.

The drive unit <NUM> moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the direction parallel to the first axis AX1. In the embodiment illustrated in <FIG>, the rotary shaft <NUM> and the inner ring <NUM> are integrally movable relative to the support member <NUM> and the outer ring <NUM>. The drive unit <NUM> may be any unit that is capable of moving a certain member relative to another member.

In the embodiment illustrated in <FIG>, the drive unit <NUM> is capable of moving the rotary shaft <NUM> relative to the support member <NUM> in the first direction DR1 parallel to the first axis AX1 so that the first contact surface C1 comes into contact with the second contact surface C2. When the first contact surface C1 comes into contact with the second contact surface C2, the rotation of the rotary shaft <NUM> is locked (see <FIG>).

Additionally, in the embodiment illustrated in <FIG>, the drive unit <NUM> is capable of moving the inner ring <NUM> relative to the outer ring <NUM> in the first direction DR1 so that the precompression that acts on the plurality of balls <NUM> (in other words, the precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM>) is reduced. In the embodiment illustrated in <FIG> and <FIG>, the drive unit <NUM> moves the inner ring <NUM> by moving the rotary shaft <NUM>, which supports the inner ring <NUM>.

In the embodiment illustrated in <FIG>, the drive unit <NUM> is capable of switching from an unlocked state in which the rotation of the rotary shaft <NUM> is permitted (more specifically, the state in which the first contact surface C1 is separate from the second contact surface C2) to a locked state in which the rotation of the rotary shaft <NUM> is locked (more specifically, the state in which the first contact surface C1 is in contact with the second contact surface C2) by moving the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1. First precompression that acts on the plurality of balls <NUM> (in other words, the first precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM>) in the locked state is smaller than second precompression that acts on the plurality of balls <NUM> (in other words, the second precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM>) in the unlocked state. The first precompression may be approximately zero.

It should be noted that, in the present description, the "unlocked state" means the state in which the rotary shaft <NUM> is rotatable about the first axis AX1, and the "locked state" means the state in which the rotary shaft <NUM> cannot rotate about the first axis AX1.

According to the rotary shaft locking device 10A of the first embodiment and the machining head 1A of the first embodiment, the drive unit <NUM> moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1. This locks the rotation of the rotary shaft <NUM> and also reduces the precompression that acts on the plurality of balls <NUM>. In this manner, in the state in which the rotation of the rotary shaft <NUM> is locked, the load that acts on the plurality of balls <NUM> of the first angular contact ball bearing <NUM> is reduced.

Furthermore, moving the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1 may form a gap G (see <FIG>) that permits each of the plurality of balls <NUM> to move relative to the inner ring <NUM> and the outer ring <NUM> in any direction (in other words, all directions).

<FIG> shows the state in which one of the plurality of balls <NUM> (hereinafter, referred to as a "first ball <NUM>-<NUM>") is made movable relative to the inner ring <NUM> and the outer ring <NUM> in any direction by moving the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1. In <FIG>, an imaginary spherical surface Q (refer to a circle drawn with an alternate long and short dash line in <FIG>), which is in contact with both an outer surface 31n of the inner ring <NUM> (more specifically, a first curved surface 31c, which will be described later) and an inner surface 33n of the outer ring <NUM> (more specifically, a second curved surface 33c, which will be described later), is greater than the diameter of the first ball <NUM>-<NUM>. In this case, a gap formed inward of the imaginary spherical surface Q functions as the gap G, which permits the first ball <NUM>-<NUM> to move relative to the inner ring <NUM> and the outer ring <NUM> in any direction (in other words, all directions). The gap G is formed for each of the plurality of balls <NUM>. It will be readily understood that the shape of the gap G formed for each ball <NUM> is not limited to a sphere.

The fact that the movement of each of the plurality of balls <NUM> is permitted in the state in which the rotation of the rotary shaft <NUM> is locked means that the load that acts on the plurality of balls <NUM> from the inner ring <NUM> of the first angular contact ball bearing <NUM> is not transmitted to the outer ring <NUM>. More specifically, in the state in which the rotation of the rotary shaft <NUM> is locked, the load that acts on the plurality of balls <NUM> from the inner ring <NUM> of the first angular contact ball bearing <NUM> in the axial direction (in other words, the load in the second direction DR2) is not transmitted to the outer ring <NUM>, and the load that acts on the plurality of balls <NUM> from the inner ring <NUM> of the first angular contact ball bearing <NUM> in the radial direction (in other words, the load in the direction perpendicular to the second direction DR2) is not transmitted to the outer ring <NUM>.

For example, assume a case in which a workpiece is turned using a lathe tool mounted on the mounting portion <NUM> of the rotary shaft <NUM> with the rotation of the rotary shaft <NUM> locked (see <FIG>). In this case, due to the vibration of the rotary shaft <NUM>, fretting (in other words, wearing out of the contact surface due to slight vibration) is likely to occur on the contact surfaces between the plurality of balls <NUM> and the rings (<NUM> and <NUM>). In contrast, according to the first embodiment, the above-mentioned fretting is inhibited or reduced since the precompression that acts on the plurality of balls <NUM> is reduced in the state in which the rotation of the rotary shaft <NUM> is locked. Typically, the above-mentioned fretting is further inhibited or reduced since the load that acts on the plurality of balls <NUM> from the inner ring <NUM> is not transmitted to the outer ring <NUM>. Inhibiting or reducing the fretting prolongs the durability life of the rotary shaft <NUM> and improves the reliability of the device including the rotary shaft <NUM>. Since the fretting of the contact surfaces between the plurality of balls <NUM> and the rings (<NUM> and <NUM>) is kept inhibited or reduced, the rotary shaft <NUM> is permitted to rotate about the first axis AX1 at high speed. In other words, the durability life of the rotary shaft <NUM> is sufficiently maintained even when the rotary shaft <NUM> is used in high-speed rotation.

In the embodiment illustrated in <FIG>, oil exists in the space SP between the inner ring <NUM> and the outer ring <NUM>. The oil is supplied from, for example, an oil supply hole <NUM> located in the first angular contact ball bearing <NUM> (more specifically, the outer ring <NUM>). Alternatively or additionally, grease may be sealed in the space SP between the inner ring <NUM> and the outer ring <NUM>.

In the state in which the rotation of the rotary shaft <NUM> is locked, the inner ring <NUM> does not rotate relative to the outer ring <NUM>. At this time, if great precompression acts on the balls <NUM> from the inner ring <NUM> and the outer ring <NUM>, an oil film is not sufficiently formed around the balls <NUM>. However, in the embodiment illustrated in <FIG>, the precompression that acts on the balls <NUM> is reduced in the state in which the rotation of the rotary shaft <NUM> is locked. Thus, the oil effectively protects the circumference of the balls <NUM>. Since the oil protects the circumference of the balls <NUM>, fretting is further effectively inhibited from occurring on the contact surfaces between the balls <NUM> and the rings (<NUM> and <NUM>).

Subsequently, optional structures that can be employed by the rotary shaft locking device 10A according to the first embodiment or the machining head 1A according to the first embodiment will be described with reference to <FIG>.

In the embodiment illustrated in <FIG>, the drive unit <NUM> moves the rotary shaft <NUM> relative to the support member <NUM> in the second direction DR2, which is opposite to the first direction DR1, so that the first contact surface C1 of the rotary shaft <NUM> separates from the second contact surface C2 of the support member <NUM> (see <FIG>). This unlocks the rotary shaft <NUM>. Additionally, the drive unit <NUM> moves the inner ring <NUM> relative to the outer ring <NUM> in the second direction DR2, so that the precompression that acts on the plurality of balls <NUM> is increased (see <FIG>). In the embodiment illustrated in <FIG> and <FIG>, the drive unit <NUM> moves the inner ring <NUM> by moving the rotary shaft <NUM>, which supports the inner ring <NUM>.

In the embodiment illustrated in <FIG>, the drive unit <NUM> is capable of switching the state of the rotary shaft <NUM> from the locked state (see <FIG>) to the unlocked state (see <FIG>) by moving the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the second direction DR2. The second precompression that acts on the plurality of balls <NUM> in the unlocked state is greater than the first precompression that acts on the plurality of balls <NUM> in the locked state.

In the embodiment illustrated in <FIG>, the drive unit <NUM> moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the second direction DR2 to unlock the rotary shaft <NUM> and also to increase the precompression that acts on the plurality of balls <NUM>. Thus, in the unlocked state in which the rotation of the rotary shaft <NUM> is permitted, the axial load that acts on the rotary shaft <NUM> is supported by the first angular contact ball bearing <NUM> in a suitable manner.

For example, assume a case in which a workpiece is machined using a milling tool mounted on the mounting portion of the rotary shaft <NUM> by rotating the rotary shaft <NUM> about the first axis AX1 in the unlocked state (see <FIG>). In this case, the axial load that acts on the rotary shaft <NUM> from the milling tool is supported by the first angular contact ball bearing <NUM> in a suitable manner.

In the embodiment illustrated in <FIG>, the first angular contact ball bearing <NUM> includes the inner ring <NUM>, the outer ring <NUM>, and the plurality of balls <NUM>. The first angular contact ball bearing <NUM> may include a retainer <NUM> (more specifically, a ring-shaped retainer), which keeps the gap between two adjacent balls <NUM>. The retainer <NUM> includes a plurality of through-holes <NUM>, which receive the plurality of balls <NUM>, respectively.

In the embodiment illustrated in <FIG>, the inner ring <NUM> includes a first shoulder portion <NUM>, and the outer ring <NUM> includes a second shoulder portion <NUM>. In the embodiment illustrated in <FIG>, when the inner ring <NUM> moves relative to the outer ring <NUM> in the first direction DR1, the first shoulder portion <NUM> moves in the direction away from the second shoulder portion <NUM>. When the first shoulder portion <NUM> moves in the direction away from the second shoulder portion <NUM>, the precompression that acts on the plurality of balls <NUM> (in other words, the precompression that the plurality of balls <NUM> receive from the first shoulder portion <NUM> and the second shoulder portion <NUM>) is reduced.

In the embodiment illustrated in <FIG>, the rear surface of the first shoulder portion <NUM> includes a first curved surface 31c, which applies diagonally rearward precompression on the plurality of balls <NUM>, and the front surface of the second shoulder portion <NUM> includes a second curved surface 33c, which applies diagonally forward precompression on the plurality of balls <NUM>. When the inner ring <NUM> moves relative to the outer ring <NUM> in the first direction DR1, the first curved surface 31c moves in the direction away from the second curved surface 33c.

In the embodiment illustrated in <FIG>, the first angular contact ball bearing <NUM> has a frontal arrangement in which the first angular contact ball bearing <NUM> supports the axial load that acts in the direction from the distal end of the rotary shaft <NUM> to the rear end of the rotary shaft <NUM>. It should be noted that in the present description, the "frontal arrangement" means the arrangement that is capable of supporting the axial load that acts in the direction from the distal end of the rotary shaft <NUM> to the rear end of the rotary shaft <NUM>. Typically, in the first angular contact ball bearing <NUM> having the frontal arrangement, the first shoulder portion <NUM> of the inner ring <NUM> is located forward of the second shoulder portion <NUM> of the outer ring <NUM>.

In the embodiment illustrated in <FIG>, the first angular contact ball bearing <NUM> includes a first angular contact ball bearing assembly 30a, which is a first bearing unit. The first angular contact ball bearing assembly 30a has the frontal arrangement in which the first angular contact ball bearing assembly 30a supports the axial load that acts in the direction from the distal end of the rotary shaft <NUM> to the rear end of the rotary shaft <NUM>.

In the embodiment illustrated in <FIG>, the first angular contact ball bearing assembly 30a includes an inner ring 31a, an outer ring 33a, and a plurality of balls 35a located between the inner ring 31a and the outer ring 33a.

The inner ring 31a of the first angular contact ball bearing assembly 30a includes the first shoulder portion <NUM>, and the outer ring 33a includes a counter bore 330t (in other words, a shoulderless portion), which faces the first shoulder portion <NUM>. The outer ring 33a of the first angular contact ball bearing assembly 30a includes the second shoulder portion <NUM>, and the inner ring 31a includes a counter bore 310t (in other words, a shoulderless portion), which faces the second shoulder portion <NUM>.

In the embodiment illustrated in <FIG>, the first angular contact ball bearing <NUM> includes a second angular contact ball bearing assembly 30b, which is a second bearing unit. The second angular contact ball bearing assembly 30b is located further in the second direction DR2 than the first angular contact ball bearing assembly 30a. The second angular contact ball bearing assembly 30b has the frontal arrangement in which the second angular contact ball bearing assembly 30b supports the axial load that acts in the direction from the distal end of the rotary shaft <NUM> to the rear end of the rotary shaft <NUM>.

In the embodiment illustrated in <FIG>, the second angular contact ball bearing assembly 30b includes an inner ring 31b, an outer ring 33b, and a plurality of balls 35b, which are located between the inner ring 31b and the outer ring 33b.

In the embodiment illustrated in <FIG>, the first angular contact ball bearing assembly 30a located on the distal end portion <NUM> of the rotary shaft <NUM> has the frontal arrangement, and the second angular contact ball bearing assembly 30b located on the distal end portion <NUM> of the rotary shaft <NUM> has the frontal arrangement. In this case, the drive unit <NUM> is capable of moving the rotary shaft <NUM>, the inner ring 31a of the first angular contact ball bearing assembly 30a, and the inner ring 31b of the second angular contact ball bearing assembly 30b relative to the support member <NUM>, the outer ring 33a of the first angular contact ball bearing assembly 30a, and the outer ring 33b of the second angular contact ball bearing assembly 30b in the first direction DR1. Such relative movement causes the first contact surface C1 to come into contact with the second contact surface C2 with the precompression that acts on the plurality of balls (35a and 35b) reduced (typically, with each of the plurality of balls <NUM> allowed to move relative to the outer ring <NUM> and the inner ring <NUM> in any direction).

In the embodiment illustrated in <FIG>, the first angular contact ball bearing <NUM> located on the distal end portion <NUM> of the rotary shaft <NUM> includes two angular contact ball bearing assemblies (30a and 30b), which have the frontal arrangement. Alternatively, the first angular contact ball bearing <NUM>, which is located on the distal end portion <NUM> of the rotary shaft <NUM>, may include three or more angular contact ball bearing assemblies having the frontal arrangement.

In the embodiment illustrated in <FIG>, a first spacer <NUM> is located between the inner ring 31a of the first angular contact ball bearing assembly 30a and the inner ring 31b of the second angular contact ball bearing assembly 30b. The first spacer <NUM> maintains the gap between the inner ring 31a and the inner ring 31b. Additionally, a second spacer <NUM> is located between the outer ring 33a of the first angular contact ball bearing assembly 30a and the outer ring 33b of the second angular contact ball bearing assembly 30b. The second spacer <NUM> maintains the gap between the outer ring 33a and the outer ring 33b. Note that these spacers (<NUM> and <NUM>) may be omitted.

In the embodiment illustrated in <FIG>, in the state in which the rotation of the rotary shaft <NUM> is permitted, a milling tool T1 is mounted on the mounting portion <NUM> of the rotary shaft <NUM>. In the embodiment illustrated in <FIG>, in the state in which the rotation of the rotary shaft <NUM> is locked, a lathe tool T2 is mounted on the mounting portion <NUM> of the rotary shaft <NUM>. Changing the milling tool T1 to the lathe tool T2 or changing the lathe tool T2 to the milling tool T1 is performed using, for example, an automatic tool exchanger.

In the embodiment illustrated in <FIG>, the drive unit <NUM> moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1. The first direction DR1 is the direction moving from a rear end portion <NUM> of the rotary shaft <NUM> towards the distal end portion <NUM> of the rotary shaft <NUM>. In the embodiment illustrated in <FIG>, the drive unit <NUM> moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the second direction DR2. The second direction DR2 is the direction moving from the distal end portion <NUM> of the rotary shaft <NUM> to the rear end portion <NUM> of the rotary shaft <NUM>.

In the embodiment illustrated in <FIG>, the drive unit <NUM> includes a first movable member <NUM>, which directly or indirectly presses the rotary shaft <NUM>. The first movable member <NUM> is capable of pressing the rotary shaft <NUM> in the first direction DR1. The first movable member <NUM> is also capable of pressing the rotary shaft <NUM> in the second direction DR2.

In the embodiment illustrated in <FIG>, the first movable member <NUM> is located rearward of (more specifically, further in the second direction DR2 than) the first angular contact ball bearing <NUM>.

With the first movable member <NUM> located rearward of the first angular contact ball bearing <NUM>, the structure forward of the first angular contact ball bearing <NUM> is simplified. As a result, the distance between the distal end of the rotary shaft <NUM> and the first angular contact ball bearing <NUM> is reduced. The reduction in the distance between the distal end of the rotary shaft <NUM> and the first angular contact ball bearing <NUM> improves the radial stiffness of the rotary shaft <NUM>. In this case, the milling tool T1 mounted on the rotary shaft <NUM> is rotated about the first axis AX1 in a stable manner.

In the embodiment illustrated in <FIG>, the drive unit <NUM> includes a first drive unit <NUM>, which moves the first movable member <NUM>. In the embodiment illustrated in <FIG>, the first drive unit <NUM> includes a first oil chamber <NUM> and a first pipe <NUM>, which supplies oil to the first oil chamber <NUM>. The first drive unit <NUM> may include a first valve V1, which controls the flow direction of the oil in the first pipe <NUM>.

In the embodiment illustrated in <FIG>, when the oil is supplied from the first pipe <NUM> to the first oil chamber <NUM>, the first movable member <NUM> moves in the first direction DR1. When the first movable member <NUM> moves in the first direction DR1, the first movable member <NUM> presses the rotary shaft <NUM> in the first direction DR1. In the embodiment illustrated in <FIG>, the first movable member <NUM> includes a first piston <NUM>, which is hydraulically driven. The first movable member <NUM> may be constituted by one component, or may be constituted by an assembly of a plurality of components.

In the embodiment illustrated in <FIG>, the first movable member <NUM> presses the rotary shaft <NUM> through a second angular contact ball bearing <NUM>, which is located on the rear end portion <NUM> of the rotary shaft <NUM>. Alternatively, the first movable member <NUM> may directly press the rotary shaft <NUM>.

In the embodiment illustrated in <FIG>, the movable member <NUM> includes a first pressing portion 510a and a second pressing portion 510b. In the embodiment illustrated in <FIG>, when the first movable member <NUM> moves in the first direction DR1, the first pressing portion 510a of the first movable member <NUM> presses the rotary shaft <NUM> in the first direction DR1 through the second angular contact ball bearing <NUM>. In contrast, when the first movable member <NUM> moves in the second direction DR2, the second pressing portion 510b of the first movable member <NUM> presses the rotary shaft <NUM> in the second direction DR2 through the second angular contact ball bearing <NUM>.

In the embodiment illustrated in <FIG>, the first movable member <NUM> (more specifically, the first piston <NUM>) includes a pressure receiving surface <NUM>, which receives the hydraulic pressure. In the embodiment illustrated in <FIG>, the first drive unit <NUM> includes a plurality of rolling elements <NUM>, which are located around the first movable member <NUM> and guide the movement of the first movable member <NUM>. The plurality of rolling elements <NUM> are located between the outer circumferential surface of the first movable member <NUM> and the inner circumferential surface of the support member <NUM>.

In the embodiment illustrated in <FIG>, the first drive unit <NUM> includes a first urging member <NUM> (for example, a spring), which applies an urging force to the first movable member <NUM>. The first urging member <NUM> urges the first movable member <NUM> in the second direction DR2. In the embodiment illustrated in <FIG>, the first urging member <NUM> is located between the first movable member <NUM> and the support member <NUM>. In the embodiment illustrated in <FIG>, when the oil is discharged from the first oil chamber <NUM> through the first pipe <NUM>, the first movable member <NUM> moves in the second direction DR2 by the urging force of the first urging member <NUM>. When the first movable member <NUM> moves in the second direction DR2, the first movable member <NUM> presses the rotary shaft <NUM> in the second direction DR2.

In the embodiment illustrated in <FIG>, the first movable member <NUM>, which receives an urging force from the first urging member <NUM>, moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the second direction DR2 so that the first contact surface C1 of the rotary shaft <NUM> separates from the second contact surface C2 of the support member <NUM> and so that the precompression that acts on the plurality of balls <NUM> of the first angular contact ball bearing <NUM> is increased. This unlocks the rotary shaft <NUM>.

The first urging member <NUM> applies an urging force to the first movable member <NUM>, the rotary shaft <NUM>, and the inner ring <NUM> in the second direction DR2 (in other words, the direction opposite to the first direction DR1). In the embodiment illustrated in <FIG>, in the unlocked state in which the rotation of the rotary shaft <NUM> is permitted, the plurality of balls <NUM> receive, from the inner ring <NUM>, the precompression that corresponds to the amount of the urging force applied by the first urging member <NUM>. The drive unit <NUM> moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1 against the urging force of the first urging member <NUM>, so that the precompression that acts on the plurality of balls <NUM> is reduced.

In the embodiment illustrated in <FIG>, the rotary shaft locking device 10A includes the second angular contact ball bearing <NUM>, which is located on the rear end portion <NUM> of the rotary shaft <NUM>. In the embodiment illustrated in <FIG>, the second angular contact ball bearing <NUM> includes a second inner ring <NUM>, a second outer ring <NUM>, and a plurality of balls <NUM> (in other words, a second ball group).

The second inner ring <NUM> is supported by the rotary shaft <NUM>. More specifically, the second inner ring <NUM> is secured to the rotary shaft <NUM>. In the embodiment illustrated in <FIG>, the second inner ring <NUM> is located around the rear end portion <NUM> of the rotary shaft <NUM>.

In the embodiment illustrated in <FIG>, the second outer ring <NUM> is supported by the first movable member <NUM>. More specifically, the second outer ring <NUM> is secured to the first movable member <NUM>.

The plurality of balls <NUM> (in other words, the second ball group) are located between the second inner ring <NUM> and the second outer ring <NUM>.

As illustrated in <FIG>, the second angular contact ball bearing <NUM> may include a plurality of angular contact ball bearing assemblies <NUM>. Each angular contact ball bearing assembly <NUM> includes the second inner ring <NUM>, the second outer ring <NUM>, and the plurality of balls <NUM>. In the embodiment illustrated in <FIG>, the second angular contact ball bearing <NUM> is constituted by the plurality of angular contact ball bearing assemblies <NUM> located one next to the other in the direction parallel to the first direction DR1. Alternatively, the second angular contact ball bearing <NUM> may include one angular contact ball bearing assembly <NUM>.

In the embodiment illustrated in <FIG>, the second angular contact ball bearing <NUM> has a back arrangement in which the second angular contact ball bearing <NUM> supports the axial load that acts in the direction from the rear end of the rotary shaft <NUM> to the distal end of the rotary shaft <NUM> (in other words, the axial load in the first direction DR1). In the second embodiment to a fifth embodiment described below also, the second angular contact ball bearing <NUM> located on the rear end portion <NUM> of the rotary shaft <NUM> preferably has the back arrangement. It should be noted that in the present description, the "back arrangement" means the arrangement that is capable of supporting the axial load that acts in the direction from the rear end of the rotary shaft <NUM> to the distal end of the rotary shaft <NUM>.

Typically, in the second angular contact ball bearing <NUM> having the back arrangement, a third shoulder portion <NUM> of the second inner ring <NUM> is located rearward of a fourth shoulder portion <NUM> of the second outer ring <NUM>. When the plurality of balls <NUM> of the second angular contact ball bearing <NUM> are sandwiched between the third shoulder portion <NUM> and the fourth shoulder portion <NUM>, precompression acts on the plurality of balls <NUM>.

In the embodiment illustrated in <FIG>, when the rotary shaft <NUM> moves in the direction parallel to the first direction DR1, the second inner ring <NUM> of the second angular contact ball bearing <NUM> and the second outer ring <NUM> of the second angular contact ball bearing <NUM> move in the direction parallel to the first direction DR1 together with the rotary shaft <NUM>. In other words, when the rotary shaft <NUM> moves in the direction parallel to the first direction DR1, the entire second angular contact ball bearing <NUM> moves in the direction parallel to the first direction DR1 together with the rotary shaft <NUM>. This is contrasting to the fact that the outer ring <NUM> of the first angular contact ball bearing <NUM> does not move in the direction parallel to the first direction DR1 when the rotary shaft <NUM> moves in the direction parallel to the first direction DR1.

As described above, in the embodiment illustrated in <FIG>, the drive unit <NUM> is capable of moving the entire second angular contact ball bearing <NUM>, the rotary shaft <NUM>, and the inner ring <NUM> of the first angular contact ball bearing <NUM> relative to the support member <NUM> and the outer ring <NUM> of the first angular contact ball bearing <NUM> in the first direction DR1.

In the embodiment illustrated in <FIG>, when the drive unit <NUM> switches the state of the rotary shaft <NUM> from the unlocked state to the locked state, the precompression that acts on the plurality of balls <NUM> (in other words, the first ball group) is reduced. Meanwhile, when the drive unit <NUM> switches the state of the rotary shaft <NUM> from the unlocked state to the locked state, the precompression that acts on the plurality of balls <NUM> (in other words, the second ball group) may be reduced or approximately maintained.

In the embodiment illustrated in <FIG>, in the state in which the rotation of the rotary shaft <NUM> is locked, a front end face 31f of the inner ring <NUM> is located forward of (in other words, further in the first direction DR1 than) a front end face 33f of the outer ring <NUM>. By contrast, in the embodiment illustrated in <FIG>, in the state in which the rotation of the rotary shaft <NUM> is permitted, the position of the front end face 31f of the inner ring <NUM> in the direction of the first axis AX1 is approximately aligned with the position of the front end face 33f of the outer ring <NUM> in the direction of the first axis AX1.

In the embodiment illustrated in <FIG>, the machining head 1A includes the first rotary drive unit <NUM>, which rotates the rotary shaft <NUM> about the first axis AX1. The first rotary drive unit <NUM> may be a first motor. In the embodiment illustrated in <FIG>, the first rotary drive unit <NUM> (more specifically, the first motor) includes a stator <NUM> and a rotor <NUM>. In this case, when current is supplied to the stator <NUM>, the rotor <NUM> rotates about the first axis AX1 by electromagnetic action. In the embodiment illustrated in <FIG>, the stator <NUM> is secured to the support member <NUM>, and the rotor <NUM> is secured to the rotary shaft <NUM>.

In the embodiment illustrated in <FIG>, the rotor <NUM> is located on the middle portion <NUM> of the rotary shaft <NUM>. In the embodiment illustrated in <FIG>, the rotor <NUM> is located rearward of the first angular contact ball bearing <NUM> and forward of the second angular contact ball bearing <NUM>.

In the embodiment illustrated in <FIG>, the first movable member <NUM>, which presses the rotary shaft <NUM>, is located rearward of the stator <NUM>. Alternatively, the first movable member <NUM>, which presses the rotary shaft <NUM>, may be located forward of the stator <NUM>. In this case, the first movable member <NUM> directly presses the rotary shaft <NUM> without the second angular contact ball bearing <NUM>.

In the embodiment illustrated in <FIG>, the rotary shaft locking device 10A includes a locking mechanism C that locks the rotation of the rotary shaft <NUM>. In the embodiment illustrated in <FIG>, the locking mechanism C includes the first contact surface C1 of the rotary shaft <NUM> and the second contact surface C2 of the support member <NUM>. The first contact surface C1 includes a first inclined surface M1, which is inclined with respect to the first axis AX1, and the second contact surface C2 includes a second inclined surface M2, which is inclined with respect to the first axis AX1.

In the embodiment illustrated in <FIG>, the state in which the first inclined surface M1 and the second inclined surface M2 are in contact with each other corresponds to the locked state. In the embodiment illustrated in <FIG>, the state in which the first inclined surface M1 and the second inclined surface M2 are separate from each other corresponds to the unlocked state.

In the embodiment illustrated in <FIG>, when the drive unit <NUM> moves the rotary shaft <NUM> in the first direction DR1, the inner ring <NUM> moves relative to the outer ring <NUM> so that the precompression that acts on the plurality of balls <NUM> is reduced, and the first inclined surface M1 presses the second inclined surface M2. This locks the rotary shaft <NUM>.

In the embodiment illustrated in <FIG>, when the drive unit <NUM> moves the rotary shaft <NUM> in the second direction DR2, the inner ring <NUM> moves relative to the outer ring <NUM> so that the precompression that acts on the plurality of balls <NUM> is increased, and the first inclined surface M1 separates from the second inclined surface M2. This unlocks the rotary shaft <NUM>.

In the embodiment illustrated in <FIG>, the first inclined surface M1 and the second inclined surface M2 are located forward of (in other words, further in the first direction DR1 than) the first angular contact ball bearing <NUM>.

In the embodiment illustrated in <FIG>, the first inclined surface M1 is an annular inclined surface formed on the outer circumferential surface of the rotary shaft <NUM>. In the embodiment illustrated in <FIG>, the outer diameter of the first inclined surface M1 is reduced toward the front (in other words, toward the distal end 2a of the rotary shaft <NUM>).

In the embodiment illustrated in <FIG>, the second inclined surface M2 is an annular inclined surface formed on the inner circumferential surface of the support member <NUM>. The second inclined surface M2 is located on the first end wall <NUM> of the support member <NUM>. In the embodiment illustrated in <FIG>, the inner diameter of the second inclined surface M2 is reduced toward the front (in other words, toward the distal end 2a of the rotary shaft <NUM>).

In the embodiment illustrated in <FIG>, the rotary shaft <NUM> includes the rotary shaft body <NUM>, the mounting portion <NUM> on which a tool T is mounted, and a rod-like member <NUM>, which is coupled to the mounting portion <NUM>. In the embodiment illustrated in <FIG>, when a mounting portion drive unit <NUM> of the machining head 1A presses the rod-like member <NUM> in the first direction DR1, the rod-like member <NUM> and the mounting portion <NUM> move relative to the rotary shaft body <NUM> in the first direction DR1. In this state, the tool T mounted on the mounting portion <NUM> can be changed to another tool. After the tool is changed, an urging member <NUM> (for example, a disc spring) located on the rotary shaft <NUM> presses the rod-like member <NUM> in the second direction DR2. In this manner, the rod-like member <NUM> and the mounting portion <NUM> move relative to the rotary shaft body <NUM> in the second direction DR2.

In the embodiment illustrated in <FIG>, the distal end portion <NUM> of the rotary shaft <NUM> includes a recessed portion 21b, which faces a projecting portion 45b formed on the first end wall <NUM> of the support member <NUM>. The recessed portion 21b and the projecting portion 45b form a labyrinth structure that prevents the entry of liquid. The gap between the recessed portion 21b and the projecting portion 45b increases when the rotary shaft <NUM> moves relative to the support member <NUM> in the first direction DR1 (see <FIG>).

In the embodiment illustrated in <FIG>, the housing H includes the side wall <NUM>, which covers at least the middle portion <NUM> of the rotary shaft <NUM>. In the embodiment illustrated in <FIG>, the housing H includes the first end wall <NUM>. In the embodiment illustrated in <FIG>, a first hole <NUM> is formed in the first end wall <NUM>. The rotary shaft <NUM> is located to pass through the first hole <NUM>. In the embodiment illustrated in <FIG>, the inner surface of the first hole <NUM> functions as the above-mentioned second contact surface C2 (more specifically, the second inclined surface M2).

A machining head 1B and a rotary shaft locking device 10B according to a second embodiment will be described with reference to <FIG>. <FIG> is a schematic cross-sectional view of the machining head 1B according to the second embodiment. <FIG> is an enlarged view of the section indicated by circle A4 drawn with an alternate long and short dash line in <FIG>. <FIG> is a schematic diagram illustrating the state in which a first coupling <NUM> and a second coupling <NUM> are disengaged from each other. <FIG> is a schematic perspective view of the first coupling <NUM> according to an embodiment. <FIG> is a schematic cross-sectional view of the machining head 1B according to the second embodiment. <FIG> is an enlarged view of the section indicated by circle A5 drawn with an alternate long and short dash line in <FIG>. <FIG> is a schematic diagram illustrating the state in which the first coupling <NUM> and the second coupling <NUM> are engaged with each other.

In the second embodiment, the differences from the first embodiment will mainly be described. Meanwhile, in the second embodiment, redundant descriptions of items that have already been described in the first embodiment are omitted. Therefore, in the second embodiment, even without an explicit description, it will be readily understood that the items that have already been described in the first embodiment may be applied to the second embodiment.

In the second embodiment, the structure of the locking mechanism C, which locks the rotation of the rotary shaft <NUM>, differs from the structure of the locking mechanism C according to the first embodiment. The second embodiment is identical to the first embodiment in other aspects. In the second embodiment, the locking mechanism C will mainly be described, and redundant descriptions of structures other than the locking mechanism C are omitted.

As illustrated in <FIG>, the rotary shaft locking device 10B according to the second embodiment includes (<NUM>) the rotary shaft <NUM>, which includes the mounting portion <NUM> on which the tool T will be mounted and first contact surfaces C1 and is rotatable about the first axis AX1, (<NUM>) the first angular contact ball bearing <NUM>, which includes the inner ring <NUM> supported by the rotary shaft <NUM>, the outer ring <NUM>, and the plurality of balls <NUM> located between the inner ring <NUM> and the outer ring <NUM>, (<NUM>) the support member <NUM>, which includes second contact surfaces C2 that come into contact with the first contact surfaces C1 to lock the rotation of the rotary shaft <NUM> and rotatably supports the rotary shaft <NUM> through the first angular contact ball bearing <NUM>, and (<NUM>) the drive unit <NUM>, which moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1 parallel to the first axis AX1 so that the first contact surfaces C1 come into contact with the second contact surfaces C2 and so that the precompression that acts on the plurality of balls <NUM> is reduced.

The machining head 1B according to the second embodiment includes the first rotary drive unit <NUM>, which rotates the rotary shaft <NUM> about the first axis AX1, the housing H, which surrounds the rotary shaft <NUM>, and the above-mentioned rotary shaft locking device 10B.

Thus, the second embodiment has the same advantages as the first embodiment.

In the embodiment illustrated in <FIG>, the rotary shaft locking device 10B includes the locking mechanism C that locks the rotation of the rotary shaft <NUM>. The locking mechanism C includes the first coupling <NUM> and the second coupling <NUM>. In the embodiment illustrated in <FIG>, the rotary shaft <NUM> includes the first coupling <NUM>, and the support member <NUM> includes the second coupling <NUM>.

In the embodiment illustrated in <FIG>, the first coupling <NUM> (that is, the coupling on the rotary shaft <NUM>) includes the first contact surfaces C1. The first contact surfaces C1 include first inclined surfaces M1. In the embodiment illustrated in <FIG>, the second coupling <NUM> (that is, the coupling on the support member <NUM>) includes the second contact surfaces C2. The second contact surfaces C2 include second inclined surfaces M2.

In the embodiment illustrated in <FIG>, the engagement between the first coupling <NUM> and the second coupling <NUM> locks the rotation of the rotary shaft <NUM>. The state in which the first coupling <NUM> and the second coupling <NUM> are engaged with each other corresponds to the locked state, and the state in which the first coupling <NUM> and the second coupling <NUM> are disengaged from each other corresponds to the unlocked state. The drive unit <NUM> switches the state of the rotary shaft <NUM> between the locked state and the unlocked state.

More specifically, in the embodiment illustrated in <FIG>, when the drive unit <NUM> moves the rotary shaft <NUM> in the first direction DR1, the inner ring <NUM> moves relative to the outer ring <NUM> so that the precompression that acts on the plurality of balls <NUM> is reduced. Additionally, when the drive unit <NUM> moves the rotary shaft <NUM> in the first direction DR1, the first coupling <NUM> and the second coupling <NUM> engage with each other (see <FIG>). This locks the rotary shaft <NUM>. In the embodiment illustrated in <FIG>, in the state in which the rotation of the rotary shaft <NUM> is locked, the first contact surfaces C1 of the first coupling <NUM> (more specifically, the first inclined surfaces M1) are in contact with the second contact surfaces C2 of the second coupling <NUM> (more specifically, the second inclined surfaces M2).

In the embodiment illustrated in <FIG>, in the state in which the rotation of the rotary shaft <NUM> is locked, the precompression that acts on the plurality of balls <NUM> is reduced (typically, a space is formed that permits each of the plurality of balls <NUM> to move relative to the outer ring <NUM> and the inner ring <NUM> in any direction, and the load that acts on the plurality of balls <NUM> from the inner ring <NUM> is not transmitted to the outer ring <NUM>). Thus, when a workpiece is turned using the lathe tool T2 mounted on the rotary shaft <NUM> with the rotation of the rotary shaft <NUM> locked, fretting is unlikely to occur on the contact surfaces between the balls <NUM> and the rings (<NUM> and <NUM>).

In the embodiment illustrated in <FIG>, when the drive unit <NUM> moves the rotary shaft <NUM> in the second direction DR2, the inner ring <NUM> moves relative to the outer ring <NUM> so that the precompression that acts on the plurality of balls <NUM> is increased. Additionally, when the drive unit <NUM> moves the rotary shaft <NUM> in the second direction DR2, the first coupling <NUM> and the second coupling <NUM> are disengaged from each other (see <FIG>). In this manner, the rotary shaft <NUM> is unlocked from the support member <NUM>. In the embodiment illustrated in <FIG>, in the state in which the rotary shaft <NUM> is unlocked, the first contact surfaces C1 of the first coupling <NUM> are separate from the second contact surfaces C2 of the second coupling <NUM>.

In the embodiment illustrated in <FIG>, in the state in which the rotary shaft <NUM> is rotatable about the first axis AX1, the precompression that acts on the plurality of balls <NUM> is increased. Thus, in the case in which a workpiece is machined using the milling tool T1 mounted on the rotary shaft <NUM>, the axial load that acts on the milling tool T1 and the rotary shaft <NUM> is supported by the first angular contact ball bearing <NUM> in a suitable manner.

In the embodiment illustrated in <FIG>, the rotary shaft <NUM> includes the rotary shaft body <NUM> and the first coupling <NUM>, and the first coupling <NUM> is secured to the rotary shaft body <NUM> using a fastener <NUM>. In the embodiment illustrated in <FIG>, the first coupling <NUM> is located forward of the first angular contact ball bearing <NUM>.

In the embodiment illustrated in <FIG>, the second coupling <NUM> is located forward of the first coupling <NUM>. In the embodiment illustrated in <FIG>, the second coupling <NUM> is a fixed coupling that is fixed to the first block <NUM> of the support member <NUM>. The second coupling <NUM> is located on the first end wall <NUM> of the support member <NUM>. Alternatively, the second coupling <NUM> may be located on a different section of the support member <NUM>.

In the embodiment illustrated in <FIG>, the first coupling <NUM> includes a first tooth 23a, which projects toward the second coupling <NUM>. In the embodiment illustrated in <FIG>, the first tooth 23a has a distal end face 230a. The distal end face 230a will be received by a recessed portion 42b of the second coupling <NUM>. In the embodiment illustrated in <FIG>, the first coupling <NUM> includes first teeth 23a each of which includes first contact surfaces C1 (more specifically, first inclined surfaces M1). In the embodiment illustrated in <FIG>, the first inclined surfaces M1 are located on both sides of the distal end face 230a of each of the first teeth 23a of the first coupling <NUM>.

As illustrated in <FIG>, the first coupling <NUM> may include the plurality of first teeth 23a and a first annular body 23c on which the plurality of first teeth 23a are located. In the embodiment illustrated in <FIG>, the first teeth 23a project from the first annular body 23c in the first direction DR1.

In the embodiment illustrated in <FIG>, the second coupling <NUM> includes second teeth 42a, which project toward the first coupling <NUM>. In the embodiment illustrated in <FIG>, the second coupling <NUM> includes the recessed portion 42b formed between two adjacent second teeth 42a. In the embodiment illustrated in <FIG>, each of the second teeth 42a of the second coupling <NUM> has the second contact surface C2 (more specifically, the second inclined surface M2).

The second coupling <NUM> may include the plurality of second teeth 42a and a second annular body on which the plurality of second teeth 42a are located.

In the second embodiment, the engagement between the first coupling <NUM> and the second coupling <NUM> locks the rotation of the rotary shaft <NUM>. In this case, the stiffness of the rotary shaft <NUM> in the state in which the rotation of the rotary shaft <NUM> is locked is improved. Additionally, when the first coupling <NUM> and the second coupling <NUM> are engaged, the positioning accuracy of the rotary shaft <NUM> in the rotation direction about the first axis AX1 is improved. Thus, the turning is performed with higher accuracy.

A machining head 1C and a rotary shaft locking device 10C according to a third embodiment will be described with reference to <FIG>. <FIG> is a schematic cross-sectional view of the machining head 1C according to the third embodiment. <FIG> is an enlarged view of the section indicated by circle A6 drawn with an alternate long and short dash line in <FIG>. <FIG> is a schematic diagram illustrating the state in which the first coupling <NUM> and the second coupling <NUM> are disengaged from each other. <FIG> is a schematic cross-sectional view of the machining head 1C according to the third embodiment. <FIG> is an enlarged view of the section indicated by circle A7 drawn with an alternate long and short dash line in <FIG>. <FIG> is a schematic diagram illustrating the state in which the first coupling <NUM> and a third coupling <NUM> are engaged with the second coupling <NUM>.

In the third embodiment, the differences from the first embodiment and the second embodiment will mainly be described. Meanwhile, in the third embodiment, redundant descriptions of items that have already been described in the first embodiment or the second embodiment are omitted. Therefore, in the third embodiment, even without an explicit description, it will be readily understood that the items that have already been described in the first embodiment or the second embodiment may be applied to the third embodiment.

In the third embodiment, the structure of the locking mechanism C, which locks the rotation of the rotary shaft <NUM>, and the structure associated with the locking mechanism C differ from the structure of the locking mechanism C and the structure associated with the locking mechanism C according to the first embodiment and the second embodiment. The third embodiment is identical to the first embodiment or the second embodiment in other aspects. For this reason, in the third embodiment, the locking mechanism C and the structure associated with the locking mechanism C will mainly be described, and redundant descriptions of structures other than the above are omitted.

As illustrated in <FIG>, the rotary shaft locking device 10C according to the third embodiment includes (<NUM>) the rotary shaft <NUM>, which includes the mounting portion <NUM> on which the tool T will be mounted and the first contact surfaces C1 and is rotatable about the first axis AX1, (<NUM>) the first angular contact ball bearing <NUM>, which includes the inner ring <NUM> supported by the rotary shaft <NUM>, the outer ring <NUM>, and the plurality of balls <NUM> located between the inner ring <NUM> and the outer ring <NUM>, (<NUM>) the support member <NUM>, which includes the second contact surfaces C2 that come into contact with the first contact surfaces C1 to lock the rotation of the rotary shaft <NUM> and rotatably supports the rotary shaft <NUM> through the first angular contact ball bearing <NUM>, and (<NUM>) the drive unit <NUM>, which moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1 parallel to the first axis AX1 so that the first contact surfaces C1 come into contact with the second contact surfaces C2 and so that the precompression that acts on the plurality of balls <NUM> is reduced.

The machining head 1C according to the third embodiment includes the first rotary drive unit <NUM>, which rotates the rotary shaft <NUM> about the first axis AX1, the housing H, which surrounds the rotary shaft <NUM>, and the above-mentioned rotary shaft locking device 10C.

Thus, the third embodiment has the same advantages as the first embodiment.

In the embodiment illustrated in <FIG>, the rotary shaft locking device 10C includes the locking mechanism C that locks the rotation of the rotary shaft <NUM>. The locking mechanism C includes the first coupling <NUM>, the second coupling <NUM>, and the third coupling <NUM>. In the embodiment illustrated in <FIG>, the rotary shaft <NUM> includes the first coupling <NUM>, and the support member <NUM> includes the second coupling <NUM> and the third coupling <NUM>. The second coupling <NUM> is movable relative to the third coupling <NUM>. In the embodiment illustrated in <FIG>, the second coupling <NUM> is a piston driven by hydraulic pressure.

In the embodiment illustrated in <FIG>, the first coupling <NUM> (that is, the coupling on the rotary shaft <NUM>) includes the first contact surfaces C1. The first contact surfaces C1 include the first inclined surfaces M1. In the embodiment illustrated in <FIG>, the second coupling <NUM> (that is, the coupling on the support member <NUM>) includes the second contact surfaces C2, and the third coupling <NUM> (that is, the other coupling on the support member <NUM>) includes third contact surfaces C3. The second contact surfaces C2 include the second inclined surfaces M2, and the third contact surfaces C3 include third inclined surfaces M3.

The engagement of the second coupling <NUM> with both the first coupling <NUM> and the third coupling <NUM> locks the rotation of the rotary shaft <NUM>. The state in which the second coupling <NUM> is engaged with both the first coupling <NUM> and the third coupling <NUM> (see <FIG>) corresponds to the locked state, and the state in which the second coupling <NUM> is disengaged from the first coupling <NUM> (see <FIG>) corresponds to the unlocked state. In the unlocked state (see <FIG>), the second coupling <NUM> and the third coupling <NUM> may be completely disengaged, or the second coupling <NUM> and the third coupling <NUM> do not necessarily have to be completely disengaged.

The drive unit <NUM> switches the state of the rotary shaft <NUM> between the locked state and the unlocked state. In the embodiment illustrated in <FIG>, the drive unit <NUM> includes the first drive unit <NUM>, which moves the first movable member <NUM>, which presses the rotary shaft <NUM>, and a second drive unit <NUM>, which moves the second coupling <NUM>. In the embodiment illustrated in <FIG>, each of the first drive unit <NUM> and the second drive unit <NUM> functions as part of the drive unit <NUM>, which switches the state of the rotary shaft <NUM> from the unlocked state to the locked state.

The second drive unit <NUM> moves the second coupling <NUM> so that the second coupling <NUM> engages with both the first coupling <NUM> and the third coupling <NUM>.

In the embodiment illustrated in <FIG>, the second drive unit <NUM> applies a drive force to the second coupling <NUM>, which functions as a second movable member. In the embodiment illustrated in <FIG>, the second drive unit <NUM> includes a second oil chamber <NUM> and a second pipe <NUM>, which supplies oil to the second oil chamber <NUM>. The second drive unit <NUM> may include a second valve V2 (see <FIG>), which controls the flow direction of the oil in the second pipe <NUM>.

In the embodiment illustrated in <FIG>, the second drive unit <NUM> includes a second urging member <NUM> (for example, a spring), which urges the second coupling <NUM> in the direction away from the first coupling <NUM>. The second drive unit <NUM> includes a pressing member <NUM>, which presses the second coupling <NUM> in the direction away from the first coupling <NUM> (more specifically, in the first direction DR1) by the urging force of the second urging member <NUM>.

In the embodiment illustrated in <FIG>, when oil is supplied from the second pipe <NUM> to the second oil chamber <NUM>, the second coupling <NUM> moves toward the first coupling <NUM>. In the embodiment illustrated in <FIG>, when the oil is discharged from the second oil chamber <NUM> through the second pipe <NUM>, the second coupling <NUM> moves in the direction away from the first coupling <NUM> by the urging force of the second urging member <NUM>.

In the embodiment illustrated in <FIG>, when the second drive unit <NUM> moves the second coupling <NUM> toward the first coupling <NUM> (in the second direction DR2 in the embodiment illustrated in <FIG>), the second coupling <NUM> engages with the first coupling <NUM> and the third coupling <NUM>.

In the embodiment illustrated in <FIG>, when the first drive unit <NUM> moves the first movable member <NUM> in the first direction DR1, the rotary shaft <NUM> and the inner ring <NUM>, which is supported by the rotary shaft <NUM>, move in the first direction DR1. As a result, the precompression that acts on the plurality of balls <NUM> is reduced (typically, the plurality of balls <NUM> are each allowed to move relative to the outer ring <NUM> and the inner ring <NUM> in any direction). Additionally, the first contact surfaces C1 of the first coupling <NUM>, which is located on the rotary shaft <NUM>, abut against the second contact surfaces C2 of the second coupling <NUM>. This reinforces the engagement between the first coupling <NUM> and the second coupling <NUM>.

As illustrated in <FIG>, in the state in which the rotation of the rotary shaft <NUM> is locked, the first inclined surfaces M1 of the first coupling <NUM> are in contact with the second inclined surfaces M2 of the second coupling <NUM>. Additionally, in the state in which the rotation of the rotary shaft <NUM> is locked, the second inclined surfaces M2 of the second coupling <NUM> are in contact with the third inclined surfaces M3 of the third coupling <NUM>.

In the embodiment illustrated in <FIG>, when the second drive unit <NUM> (more specifically, the second urging member <NUM>) moves the second coupling <NUM> in the direction away from the first coupling <NUM> (in the first direction DR1 in the embodiment illustrated in <FIG>), the second coupling <NUM> is disengaged from the first coupling <NUM>.

In the embodiment illustrated in <FIG>, when the first drive unit <NUM> (more specifically, the first urging member <NUM>) moves the first movable member <NUM> in the second direction DR2, the rotary shaft <NUM> and the inner ring <NUM>, which is supported by the rotary shaft <NUM>, move in the second direction DR2. As a result, the precompression that acts on the plurality of balls <NUM> is increased.

As illustrated in <FIG>, in the state in which the second coupling <NUM> and the first coupling <NUM> are disengaged, the first inclined surfaces M1 of the first coupling <NUM> are separate from the second inclined surfaces M2 of the second coupling <NUM>.

In the embodiment illustrated in <FIG>, a motion stroke L1 of the inner ring <NUM> (that is, the motion stroke L1 of the inner ring <NUM> when the unlocked state is switched to the locked state) is smaller than a motion stroke L2 of the second coupling <NUM> (that is, the motion stroke L2 of the second coupling <NUM> when the unlocked state is switched to the locked state).

When the motion stroke L1 is smaller than the motion stroke L2, the first coupling <NUM> and the second coupling <NUM> are switched from the disengaged state to the engaged state mainly by the second drive unit <NUM>. In this case, the couplings (<NUM>, <NUM>) including high-stiffness teeth with a high tooth height can be employed without being restricted by the structure of the first angular contact ball bearing <NUM> (for example, the amount that the inner ring <NUM> can move relative to the outer ring <NUM> in the first direction D1, in other words, the amount of backlash of the first angular contact ball bearing <NUM>).

In a fourth embodiment described below, the motion stroke L1 of the inner ring <NUM> (that is, the motion stroke L1 of the inner ring <NUM> when the unlocked state is switched to the locked state) is also preferably smaller than the motion stroke L2 of the second coupling <NUM> (that is, the motion stroke L2 of the second coupling <NUM> when the unlocked state is switched to the locked state) (see <FIG>).

A machining head 1D and a rotary shaft locking device 10D according to a fourth embodiment will be described with reference to <FIG>. <FIG> is a schematic cross-sectional view of the machining head 1D according to the fourth embodiment. <FIG> is an enlarged view of the section indicated by circle A8 drawn with an alternate long and short dash line in <FIG>. <FIG> is a schematic cross-sectional view of the machining head 1D according to the fourth embodiment. <FIG> is an enlarged view of the section indicated by circle A9 drawn with an alternate long and short dash line in <FIG>. <FIG> is a schematic diagram illustrating the first coupling <NUM> and the third coupling <NUM> according to an embodiment. In <FIG>, the broken lines indicate the outlines of the first coupling <NUM> and the third coupling <NUM>. In <FIG>, the illustration of the teeth (23a, 44a) in the region surrounded by the broken line is omitted. <FIG> is a schematic diagram illustrating the second coupling <NUM> according to an embodiment. In <FIG>, the broken line indicates the outline of the second coupling <NUM>. In <FIG>, the illustration of the teeth (42a) in the region surrounded by the broken line is omitted.

In the fourth embodiment, the differences from the first embodiment, the second embodiment, and the third embodiment will mainly be described. Meanwhile, in the fourth embodiment, redundant descriptions of items that have already been described in the first embodiment, the second embodiment, or the third embodiment are omitted. Therefore, in the fourth embodiment, even without an explicit description, it will be readily understood that the items that have already been described in the first embodiment, the second embodiment, or the third embodiment may be applied to the fourth embodiment.

In the third embodiment, the switching of the unlocked state to the locked state includes moving the second coupling <NUM> rearward (more specifically, in the second direction DR2). Instead, in the fourth embodiment, the switching of the unlocked state to the locked state includes moving the second coupling <NUM> forward (more specifically, in the first direction DR1). In the fourth embodiment, differences from the first embodiment to the third embodiment will mainly be described regarding the locking mechanism C, the first drive unit <NUM>, the second drive unit <NUM>, the first coupling <NUM>, the second coupling <NUM>, and the third coupling <NUM>, and redundant descriptions of other structures are omitted.

As illustrated in <FIG>, the rotary shaft locking device 10D according to the fourth embodiment includes (<NUM>) the rotary shaft <NUM>, which includes the mounting portion <NUM> on which the tool T will be mounted and the first contact surfaces C1 and is rotatable about the first axis AX1, (<NUM>) the first angular contact ball bearing <NUM>, which includes the inner ring <NUM> supported by the rotary shaft <NUM>, the outer ring <NUM>, and the plurality of balls <NUM> located between the inner ring <NUM> and the outer ring <NUM>, (<NUM>) the support member <NUM>, which includes the second contact surfaces C2 that come into contact with the first contact surfaces C1 to lock the rotation of the rotary shaft <NUM> and rotatably supports the rotary shaft <NUM> through the first angular contact ball bearing <NUM>, and (<NUM>) the drive unit <NUM>, which moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1 parallel to the first axis AX1 so that the first contact surfaces C1 come into contact with the second contact surfaces C2 and so that the precompression that acts on the plurality of balls <NUM> is reduced.

The machining head 1D according to the fourth embodiment includes the first rotary drive unit <NUM>, which rotates the rotary shaft <NUM> about the first axis AX1, the housing H, which surrounds the rotary shaft <NUM>, and the above-mentioned rotary shaft locking device 10D.

Thus, the fourth embodiment has the same advantages as the first embodiment.

In the embodiment illustrated in <FIG>, the rotary shaft locking device 10D includes the locking mechanism C that locks the rotation of the rotary shaft <NUM>. The locking mechanism C includes the first coupling <NUM>, the second coupling <NUM>, and the third coupling <NUM>. In the embodiment illustrated in <FIG>, the rotary shaft <NUM> includes the first coupling <NUM>, and the support member <NUM> includes the second coupling <NUM> and the third coupling <NUM>. The second coupling <NUM> is movable relative to the third coupling <NUM>.

The state in which the second coupling <NUM> is engaged with both the first coupling <NUM> and the third coupling <NUM> (see <FIG>) corresponds to the locked state, and the state in which the second coupling <NUM> is disengaged from the first coupling <NUM> (see <FIG>) corresponds to the unlocked state. In the unlocked state (see <FIG>), the second coupling <NUM> and the third coupling <NUM> may be completely disengaged, or the second coupling <NUM> and the third coupling <NUM> do not necessarily have to be completely disengaged.

In the embodiment illustrated in <FIG>, the second coupling <NUM> driven by the second drive unit <NUM> is located rearward of (more specifically, further in the second direction DR2 than) the first coupling <NUM> and the third coupling <NUM>. This allows the drive system that drives the second coupling <NUM> to be located rearward of the third coupling <NUM>. As a result, the distance between the distal end of the rotary shaft <NUM> and the first angular contact ball bearing <NUM> is reduced, and the radial stiffness of the rotary shaft <NUM> is improved. In this case, the milling tool T1 mounted on the rotary shaft <NUM> is rotated about the first axis AX1 in a stable manner.

The drive unit <NUM> switches the state of the rotary shaft <NUM> between the locked state and the unlocked state. In the embodiment illustrated in <FIG>, the drive unit <NUM> includes the first drive unit <NUM>, which moves the first movable member <NUM>, which presses the rotary shaft <NUM>, and the second drive unit <NUM>, which moves the second coupling <NUM>. In the embodiment illustrated in <FIG>, each of the first drive unit <NUM> and the second drive unit <NUM> functions as part of the drive unit <NUM>, which switches the state of the rotary shaft <NUM> from the unlocked state to the locked state in which the rotary shaft <NUM> is locked.

In the embodiment illustrated in <FIG>, the first drive unit <NUM> includes the first oil chamber <NUM> and the first pipe <NUM>, which supplies oil to the first oil chamber <NUM>. The first drive unit <NUM> may include the first valve V1, which controls the flow direction of the oil in the first pipe <NUM>.

In the embodiment illustrated in <FIG>, the first drive unit <NUM> drives the first movable member <NUM>. The first movable member <NUM> presses the rotary shaft <NUM> through the second angular contact ball bearing <NUM>, which is located on the rear end portion <NUM> of the rotary shaft <NUM>.

Alternatively, the first movable member <NUM> may directly press the rotary shaft <NUM>. In this case, the first movable member <NUM> may be located forward of the stator <NUM>. In the embodiment illustrated in <FIG>, the first movable member <NUM> is located rearward of the stator <NUM>.

In the embodiment illustrated in <FIG>, the first movable member <NUM> includes the first piston <NUM>. In the embodiment illustrated in <FIG>, the first drive unit <NUM> includes the plurality of rolling elements <NUM>, which are located around the first piston <NUM> and guide the movement of the first piston <NUM>.

In the embodiment illustrated in <FIG>, the first drive unit <NUM> includes the first urging member <NUM> (for example, a spring), which applies an urging force to the first movable member <NUM>. The first urging member <NUM> urges the first movable member <NUM> in the second direction DR2. In the embodiment illustrated in <FIG>, the first urging member <NUM> is located between the first movable member <NUM> and the support member <NUM>.

The first urging member <NUM> applies an urging force to the first movable member <NUM>, the rotary shaft <NUM>, and the inner ring <NUM> in the second direction DR2 (in other words, the direction opposite to the first direction DR1). In the embodiment illustrated in <FIG>, in the unlocked state in which the rotation of the rotary shaft <NUM> is permitted, the plurality of balls <NUM> receive, from the inner ring <NUM>, the precompression that corresponds to the amount of the urging force applied by the first urging member <NUM>.

In the embodiment illustrated in <FIG>, the second drive unit <NUM> applies a drive force to the second coupling <NUM>, which functions as the second movable member. In the embodiment illustrated in <FIG>, the second drive unit <NUM> includes the second oil chamber <NUM> and the second pipe <NUM>, which supplies oil to the second oil chamber <NUM>. The second drive unit <NUM> may include a valve, which controls the flow direction of the oil in the second pipe <NUM>. In the embodiment illustrated in <FIG>, the valve that controls the flow direction of the oil in the second pipe <NUM> is the same as the first valve V1, which controls the flow direction of the oil in the first pipe <NUM>. Alternatively, the valve that controls the flow direction of the oil in the second pipe <NUM> may be a valve different from the first valve V1, which controls the flow direction of the oil in the first pipe <NUM>.

In the embodiment illustrated in <FIG>, the first oil chamber <NUM> and the second oil chamber <NUM> are connected to each other through the first pipe <NUM> and the second pipe <NUM>. In this case, the hydraulic pressure in the second oil chamber <NUM> is substantially equal to the hydraulic pressure in the first oil chamber <NUM>.

As illustrated in <FIG>, the second drive unit <NUM> may include a third oil chamber <NUM> and a third pipe <NUM>, which supplies oil to the third oil chamber <NUM>. The second drive unit <NUM> may include the second valve V2, which controls the flow direction of the oil in the third pipe <NUM>.

In the embodiment illustrated in <FIG>, the second valve V2, which controls the flow direction of the oil in the third pipe <NUM>, is a valve different from the first valve V1, which controls the flow direction of the oil in the second pipe <NUM>. Alternatively, the flow direction of the oil in the third pipe <NUM> and the flow direction of the oil in the second pipe <NUM> may be controlled by one switching valve.

In the embodiment illustrated in <FIG>, when the oil is supplied from the second pipe <NUM> to the second oil chamber <NUM>, the second coupling <NUM> moves toward the first coupling <NUM>. When the oil is supplied from the third pipe <NUM> to the third oil chamber <NUM>, the second coupling <NUM> moves away from the first coupling <NUM>.

In the embodiment illustrated in <FIG>, in switching the state of the rotary shaft <NUM> from the unlocked state to the locked state, the second drive unit <NUM> moves the second coupling <NUM> in the direction toward the first coupling <NUM> (in the first direction DR1 in the embodiment illustrated in <FIG>).

When the second drive unit <NUM> moves the second coupling <NUM> toward the first coupling <NUM>, the second coupling <NUM> engages with both the first coupling <NUM> and the third coupling <NUM>. This locks the rotation of the rotary shaft <NUM>.

The second drive unit <NUM> moves the second coupling <NUM>, the rotary shaft <NUM>, and the inner ring <NUM> integrally in the first direction DR1 with the second coupling <NUM> and the first coupling <NUM> engaged with each other. More specifically, when the second drive unit <NUM> moves the second coupling <NUM> in the first direction DR1, the second coupling <NUM> presses the rotary shaft <NUM> in the first direction DR1 through the first coupling <NUM>. As a result, the rotary shaft <NUM> and the inner ring <NUM>, which is supported by the rotary shaft <NUM>, move relative to the outer ring <NUM> in the first direction DR1. When the inner ring <NUM> moves relative to the outer ring <NUM> in the first direction DR1, the precompression that acts on the plurality of balls <NUM> is reduced (typically, a space is formed that permits each of the plurality of balls <NUM> to move relative to the outer ring <NUM> and the inner ring <NUM> in any direction, and the load that acts on the plurality of balls <NUM> from the inner ring <NUM> is not transmitted to the outer ring <NUM>).

In the embodiment illustrated in <FIG>, in switching the state of the rotary shaft <NUM> from the unlocked state to the locked state, the second drive unit <NUM> applies a first pressing force to the rotary shaft <NUM> in the first direction DR1, and the first drive unit <NUM> applies a second pressing force to the rotary shaft <NUM> in the second direction DR2.

More specifically, in the embodiment illustrated in <FIG>, the second drive unit <NUM> increases the hydraulic pressure in the second oil chamber <NUM>. When the hydraulic pressure in the second oil chamber <NUM> is increased, the second coupling <NUM> moves in the first direction DR1, and the second coupling <NUM> presses the first coupling <NUM> and the rotary shaft <NUM> in the first direction DR1 (first pressing force). Additionally, in the embodiment illustrated in <FIG>, the first drive unit <NUM> increases the hydraulic pressure in the first oil chamber <NUM>. When the hydraulic pressure in the first oil chamber <NUM> is increased, the first movable member <NUM> presses the rotary shaft <NUM> in the second direction DR2 (second pressing force).

When the rotary shaft <NUM> receives the first pressing force from the second coupling <NUM> and the second pressing force from the first movable member <NUM>, the first contact surfaces C1 of the first coupling <NUM>, which is located on the rotary shaft <NUM>, strongly abut against the second contact surfaces C2 of the second coupling <NUM>, which is located on the support member <NUM>. This reinforces the locking of the rotation of the rotary shaft <NUM>. Since the second contact surfaces C2 of the second coupling <NUM> reliably abut against both the first contact surfaces C1 of the first coupling <NUM> and the third contact surfaces C3 of the third coupling <NUM>, the positioning accuracy of the rotary shaft <NUM> in the rotation direction about the first axis AX1 is improved regardless of the machining accuracy or the assembly accuracy of the couplings (<NUM>, <NUM>, and <NUM>).

When the state of the rotary shaft <NUM> is switched from the unlocked state to the locked state, the first pressing force that the second drive unit <NUM> applies to the rotary shaft <NUM> in the first direction DR1 is greater than the second pressing force that the first drive unit <NUM> applies to the rotary shaft <NUM> in the second direction DR2. Since the first pressing force in the first direction DR1 is greater than the second pressing force in the second direction DR2, the rotary shaft <NUM> and the inner ring <NUM> move relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1.

In the embodiment illustrated in <FIG>, in order to make the first pressing force to be greater than the second pressing force, the area of a pressure receiving surface <NUM> of the second coupling <NUM> facing the second oil chamber <NUM> is greater than the area of the pressure receiving surface <NUM> of the first movable member <NUM> facing the first oil chamber <NUM>. Alternatively or additionally, in order to make the first pressing force to be greater than the second pressing force, the hydraulic pressure in the second oil chamber <NUM> may be made greater than the hydraulic pressure in the first oil chamber <NUM>.

In the embodiment illustrated in <FIG>, in switching the state of the rotary shaft <NUM> from the locked state to the unlocked state, the second drive unit <NUM> moves the second coupling <NUM> in the direction away from the first coupling <NUM> (in the second direction DR2 in the embodiment illustrated in <FIG>). As a result, the second coupling <NUM> and the first coupling <NUM> are disengaged from each other.

More specifically, in the embodiment illustrated in <FIG>, the second drive unit <NUM> decreases the hydraulic pressure in the second oil chamber <NUM> and increases the hydraulic pressure in the third oil chamber <NUM>. When the hydraulic pressure in the third oil chamber <NUM> is increased, the second coupling <NUM> moves in the second direction DR2, so that the second coupling <NUM> and the first coupling <NUM> are disengaged from each other. In the embodiment illustrated in <FIG>, the first oil chamber <NUM> and the second oil chamber <NUM> are connected to each other through the first pipe <NUM> and the second pipe <NUM>. Thus, when the hydraulic pressure in the second oil chamber <NUM> is decreased, the hydraulic pressure in the first oil chamber <NUM> is also decreased.

When the second coupling <NUM> is disengaged from the first coupling <NUM>, the first pressing force in the first direction DR1 that the rotary shaft <NUM> has received from the second coupling <NUM> is removed. As a result, the rotary shaft <NUM> and the inner ring <NUM> move relative to the support member <NUM> and the outer ring <NUM> in the second direction DR2 by the second pressing force in the second direction DR2 that the rotary shaft <NUM> receives from the first drive unit <NUM> (more specifically, the first urging member <NUM>). The relative movement increases the precompression that acts on the plurality of balls <NUM>.

In the embodiment illustrated in <FIG>, the rotary shaft <NUM> includes the rotary shaft body <NUM> and the first coupling <NUM>, which is secured to the rotary shaft body <NUM> using the fastener <NUM>. Additionally, in the embodiment illustrated in <FIG>, the first coupling <NUM> is located forward of the first angular contact ball bearing <NUM>.

In the embodiment illustrated in <FIG>, the first coupling <NUM> includes the first teeth 23a. The first teeth 23a project toward the second coupling <NUM>.

The first coupling <NUM> may include the plurality of first teeth 23a and the first annular body 23c on which the plurality of first teeth 23a are located. In the embodiment illustrated in <FIG>, the first teeth 23a each have the distal end face 230a. The distal end faces 230a will be received by the recessed portions 42b of the second coupling <NUM>. In the embodiment illustrated in <FIG>, each of the first teeth 23a has the first contact surfaces C1 (more specifically, the first inclined surfaces M1). In the embodiment illustrated in <FIG>, the first inclined surfaces M1 are located on both sides of the distal end face 230a of each of the first teeth 23a.

In the embodiment illustrated in <FIG>, the support member <NUM> includes the first block <NUM>, which supports the outer ring <NUM> of the first angular contact ball bearing <NUM>, and the second coupling <NUM>, which is movable relative to the first block <NUM>. The second coupling <NUM> is a movable coupling that is movable relative to the first block <NUM>. The second coupling <NUM> is, for example, a piston driven by hydraulic pressure.

In the embodiment illustrated in <FIG>, the second coupling <NUM> includes the second teeth 42a. The second teeth 42a project toward the first coupling <NUM>.

The second coupling <NUM> may include the plurality of second teeth 42a and a second annular body 42c on which the plurality of second teeth 42a are located. In the embodiment illustrated in <FIG>, the second coupling <NUM> includes the recessed portions 42b each of which is formed between two adjacent second teeth 42a. In the embodiment illustrated in <FIG>, each of the second teeth 42a has the second contact surfaces C2 (more specifically, the second inclined surfaces M2). In the embodiment illustrated in <FIG>, the second inclined surfaces M2 are located on both sides of a distal end face 420a of each of the second teeth 42a.

In the state in which the rotation of the rotary shaft <NUM> is locked, the second contact surfaces C2 of the second coupling <NUM> abut against the first contact surfaces C1 of the first coupling <NUM> and the third contact surfaces C3 of the third coupling <NUM>. By contrast, in the state in which the rotary shaft <NUM> is rotatable about the first axis AX1, the second contact surfaces C2 of the second coupling <NUM> are separate from the first contact surfaces C1 of the first coupling <NUM> and the third contact surfaces C3 of the third coupling <NUM>.

In the embodiment illustrated in <FIG>, the support member <NUM> includes the third coupling <NUM>. The third coupling <NUM> is a fixed coupling fixed to the first block <NUM>.

In the embodiment illustrated in <FIG>, the third coupling <NUM> is located outward of and concentrically to the first coupling <NUM>. The third coupling <NUM> includes third teeth 44a. The third teeth 44a project toward the second coupling <NUM>.

The third coupling <NUM> may include the plurality of third teeth 44a and a third annular body 44c on which the plurality of third teeth 44a are located. In the embodiment illustrated in <FIG>, the third teeth 44a each have a distal end face 440a. The distal end faces 440a will be received by the recessed portions 42b of the second coupling <NUM>. In the embodiment illustrated in <FIG>, each of the third teeth 44a has the third contact surfaces C3 (more specifically, the third inclined surfaces M3). In the embodiment illustrated in <FIG>, the third inclined surfaces M3 are located on both sides of the distal end face 440a of each of the third teeth 44a of the third coupling <NUM>.

In the embodiment illustrated in <FIG>, the support member <NUM> includes the first end wall <NUM>, the second coupling <NUM>, the third coupling <NUM>, the first block <NUM>, which supports the outer ring <NUM> of the first angular contact ball bearing <NUM>, and the side wall <NUM>, which covers at least the middle portion <NUM> of the rotary shaft <NUM>.

The multi-tasking machine <NUM> according to a fifth embodiment will be described with reference to <FIG>. <FIG> is a schematic perspective view of the multi-tasking machine <NUM> according to the fifth embodiment.

The multi-tasking machine <NUM> according to the fifth embodiment includes the machining head <NUM>, a workpiece holding device <NUM>, a machining head drive unit <NUM>, and a controller <NUM>. The multi-tasking machine means a machine tool that can perform different kinds of machining operations. In the embodiment illustrated in <FIG>, the multi-tasking machine <NUM> is capable of selectively executing at least turning and milling. The multi-tasking machine <NUM> may include an automatic tool changer <NUM>, which automatically changes the tool mounted on the rotary shaft <NUM> to another tool.

The machining head <NUM> includes the rotary shaft locking device <NUM>, the first rotary drive unit <NUM>, which rotates the rotary shaft <NUM> about the first axis AX1, and the housing H, which surrounds the rotary shaft <NUM>. The rotary shaft locking device <NUM> may be the rotary shaft locking device 10A according to the first embodiment, the rotary shaft locking device 10B according to the second embodiment, the rotary shaft locking device 10C according to the third embodiment, the rotary shaft locking device 10D according to the fourth embodiment, or other rotary shaft locking devices.

The rotary shaft locking device <NUM> includes (<NUM>) the rotary shaft <NUM>, which includes the mounting portion <NUM> on which the tool T will be mounted and the first contact surface(s) C1 and is rotatable about the first axis AX1, (<NUM>) the first angular contact ball bearing <NUM>, which includes the inner ring <NUM> supported by the rotary shaft <NUM>, the outer ring <NUM>, and the plurality of balls <NUM> located between the inner ring <NUM> and the outer ring <NUM>, (<NUM>) the support member <NUM>, which includes the second contact surface(s) C2 that comes into contact with the first contact surface(s) C1 to lock the rotation of the rotary shaft <NUM> and rotatably supports the rotary shaft <NUM> through the first angular contact ball bearing <NUM>, and (<NUM>) the drive unit <NUM>, which moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1 parallel to the first axis AX1.

Since the rotary shaft locking device <NUM> has been described in the first embodiment to the fourth embodiment, redundant descriptions of the rotary shaft locking device <NUM> are omitted.

The workpiece holding device <NUM> holds a workpiece. The workpiece holding device <NUM> includes a workpiece holder <NUM> (for example, a chuck), which holds the workpiece, a second support member <NUM>, which rotatably supports the workpiece holder <NUM> about a second axis AX2, and a second rotary drive unit <NUM> (for example, a second motor), which rotates the workpiece holder <NUM> about the second axis AX2. With the lathe tool T2 that is mounted on the rotary shaft <NUM> of the rotary shaft locking device <NUM> in contact with the workpiece, the workpiece and the workpiece holder <NUM> are rotated about the second axis AX2, so that turning of the workpiece is performed. In the embodiment illustrated in <FIG>, the workpiece holding device <NUM> is supported by a base <NUM>.

The machining head drive unit <NUM> moves the machining head <NUM> relative to the workpiece holding device <NUM>. The machining head drive unit <NUM> may be a drive unit that can move the machining head <NUM> three-dimensionally. More specifically, the machining head drive unit <NUM> may be capable of moving the machining head <NUM> along a Z axis, an X axis, which is perpendicular to the Z axis, and a Y axis, which is perpendicular to both the X axis and the Z axis. In the embodiment illustrated in <FIG>, the machining head drive unit <NUM> is supported by the base <NUM>.

The controller <NUM> controls the operation of the drive unit <NUM>, the first rotary drive unit <NUM>, the second rotary drive unit <NUM>, and the machining head drive unit <NUM>.

In response to the controller <NUM> transmitting a first control signal to the machining head drive unit <NUM>, the machining head drive unit <NUM> moves the machining head <NUM> relative to the workpiece holding device <NUM>. In this manner, the tool T mounted on the rotary shaft <NUM> is moved toward or away from the workpiece.

In response to the controller <NUM> transmitting a second control signal to the first rotary drive unit <NUM>, the first rotary drive unit <NUM> rotates the rotary shaft <NUM> about the first axis AX1. In this manner, milling of the workpiece is performed using the milling tool T1 mounted on the rotary shaft <NUM>.

In response to the controller <NUM> transmitting a third control signal to the second rotary drive unit <NUM>, the second rotary drive unit <NUM> rotates the workpiece holder <NUM> about the second axis AX2. In this manner, the workpiece held by the workpiece holder <NUM> is turned using the lathe tool T2 mounted on the rotary shaft <NUM>.

In response to the controller <NUM> transmitting a fourth control signal to the drive unit <NUM> (for example, to the first drive unit <NUM> or to the first drive unit <NUM> and the second drive unit <NUM>), the drive unit <NUM> moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the first direction DR1 so that the first contact surface(s) C1 comes into contact with the second contact surface(s) C2 and so that the precompression that acts on the plurality of balls <NUM> is reduced.

In the embodiment illustrated in <FIG> or <FIG>, in response to receiving the fourth control signal, the drive unit <NUM> (more specifically, the first drive unit <NUM>) moves the first movable member <NUM> in the first direction DR1. When the first movable member <NUM> moves in the first direction DR1, the rotary shaft <NUM> pressed by the first movable member <NUM> moves relative to the support member <NUM> in the first direction DR1. When the rotary shaft <NUM> moves relative to the support member <NUM> in the first direction DR1, the first contact surface(s) C1 of the rotary shaft <NUM> comes into contact with the second contact surface(s) C2 of the support member <NUM>, so that the rotation of the rotary shaft <NUM> is locked. Additionally, when the rotary shaft <NUM> moves relative to the support member <NUM> in the first direction DR1, the inner ring <NUM>, which is supported by the rotary shaft <NUM>, moves relative to the outer ring <NUM>, which is supported by the support member <NUM>, in the first direction DR1. As a result, the precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM> is reduced. Typically, the plurality of balls <NUM> are each allowed to move relative to the outer ring <NUM> and the inner ring <NUM> in any direction (in other words, all directions), and the load that acts on the plurality of balls <NUM> from the inner ring <NUM> is not transmitted to the outer ring <NUM>.

In the embodiment illustrated in <FIG> and <FIG>, in response to the drive unit <NUM> (more specifically, the first drive unit <NUM> and the second drive unit <NUM>) receiving the fourth control signal, the second drive unit <NUM> moves the second coupling <NUM> in the second direction DR2, and the first drive unit <NUM> moves the first movable member <NUM> in the first direction DR1. When the second coupling <NUM> moves in the second direction DR2, the second coupling <NUM> engages with both the first coupling <NUM>, which is located on the rotary shaft <NUM>, and the third coupling <NUM>, which is located on the support member <NUM>. This locks the rotation of the rotary shaft <NUM>. Additionally, when the first movable member <NUM> moves in the first direction DR1, the rotary shaft <NUM> pressed by the first movable member <NUM> moves relative to the support member <NUM> in the first direction DR1. When the rotary shaft <NUM> moves relative to the support member <NUM> in the first direction DR1, the inner ring <NUM>, which is supported by the rotary shaft <NUM>, moves relative to the outer ring <NUM>, which is supported by the support member <NUM>, in the first direction DR1. As a result, the precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM> is reduced.

In the embodiment illustrated in <FIG> and <FIG>, in response to the drive unit <NUM> (more specifically, the first drive unit <NUM> and the second drive unit <NUM>) receiving the fourth control signal, the second drive unit <NUM> moves the second coupling <NUM> in the first direction DR1, and the first drive unit <NUM> applies the second pressing force to the rotary shaft <NUM> in the second direction DR2. When the second coupling <NUM> moves in the first direction DR1, the second coupling <NUM> engages with both the first coupling <NUM>, which is located on the rotary shaft <NUM>, and the third coupling <NUM>, which is located on the support member <NUM>. This locks the rotation of the rotary shaft <NUM>. Additionally, when the second coupling <NUM> moves in the first direction DR1, the second coupling <NUM> applies the first pressing force greater than the above-mentioned second pressing force to the rotary shaft <NUM> in the first direction DR1. The rotary shaft <NUM> that receives the first pressing force greater than the second pressing force moves relative to the support member <NUM> in the first direction DR1. When the rotary shaft <NUM> moves relative to the support member <NUM> in the first direction DR1, the inner ring <NUM>, which is supported by the rotary shaft <NUM>, moves relative to the outer ring <NUM>, which is supported by the support member <NUM>, in the first direction DR1. As a result, the precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM> is reduced. Typically, the plurality of balls <NUM> are each allowed to move relative to the outer ring <NUM> and the inner ring <NUM> in any direction (in other words, all directions), and the load that acts on the plurality of balls <NUM> from the inner ring <NUM> is not transmitted to the outer ring <NUM>.

In this manner, in the state in which the rotation of the rotary shaft <NUM> is locked, the load that acts on the plurality of balls <NUM> of the first angular contact ball bearing <NUM> is reduced.

In response to the controller <NUM> transmitting a fifth control signal to the drive unit <NUM> (for example, to the first drive unit <NUM> or to the first drive unit <NUM> and the second drive unit <NUM>), the drive unit <NUM> moves the rotary shaft <NUM> and the inner ring <NUM> relative to the support member <NUM> and the outer ring <NUM> in the second direction DR2 so that the first contact surface(s) C1 separates from the second contact surface(s) C2 and so that the precompression that acts on the plurality of balls <NUM> is increased.

In the embodiment illustrated in <FIG> or <FIG>, in response to receiving the fifth control signal, the drive unit <NUM> (more specifically, the first drive unit <NUM>) moves the first movable member <NUM> in the second direction DR2. For example, when the first movable member <NUM> receives an urging force from the first urging member <NUM> in the second direction DR2, the first movable member <NUM> moves in the second direction DR2. When the first movable member <NUM> moves in the second direction DR2, the rotary shaft <NUM> pressed by the first movable member <NUM> moves relative to the support member <NUM> in the second direction DR2. When the rotary shaft <NUM> moves relative to the support member <NUM> in the second direction DR2, the first contact surface(s) C1 of the rotary shaft <NUM> separates from the second contact surface(s) C2 of the support member <NUM>, so that the rotary shaft <NUM> is unlocked. Additionally, when the rotary shaft <NUM> moves relative to the support member <NUM> in the second direction DR2, the inner ring <NUM>, which is supported by the rotary shaft <NUM>, moves relative to the outer ring <NUM> in the second direction DR2. As a result, the precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM> is increased.

In the embodiment illustrated in <FIG> and <FIG>, in response to the drive unit <NUM> (more specifically, the first drive unit <NUM> and the second drive unit <NUM>) receiving the fifth control signal, the second drive unit <NUM> moves the second coupling <NUM> in the first direction DR1, and the first drive unit <NUM> moves the first movable member <NUM> in the second direction DR2. When the second coupling <NUM> moves in the first direction DR1, the second coupling <NUM> is disengaged from the first coupling <NUM>, which is located on the rotary shaft <NUM>. This unlocks the rotary shaft <NUM>. Additionally, when the first movable member <NUM> moves in the second direction DR2, the rotary shaft <NUM> pressed by the first movable member <NUM> moves relative to the support member <NUM> in the second direction DR2. When the rotary shaft <NUM> moves relative to the support member <NUM> in the second direction DR2, the inner ring <NUM>, which is supported by the rotary shaft <NUM>, moves relative to the outer ring <NUM> in the second direction DR2. As a result, the precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM> is increased.

In the embodiment illustrated in <FIG> and <FIG>, in response to the drive unit <NUM> (more specifically, the first drive unit <NUM> and the second drive unit <NUM>) receiving the fifth control signal, the second drive unit <NUM> moves the second coupling <NUM> in the second direction DR2, and the first drive unit <NUM> (more specifically, the first urging member <NUM>) moves the first movable member <NUM> in the second direction DR2.

When the second coupling <NUM> moves in the second direction DR2, the second coupling <NUM> is disengaged from the first coupling <NUM>, which is located on the rotary shaft <NUM>. This unlocks the rotary shaft <NUM>. Additionally, when the first movable member <NUM> moves in the second direction DR2, the rotary shaft <NUM> pressed by the first movable member <NUM> moves relative to the support member <NUM> in the second direction DR2. When the rotary shaft <NUM> moves relative to the support member <NUM> in the second direction DR2, the inner ring <NUM>, which is supported by the rotary shaft <NUM>, moves relative to the outer ring <NUM> in the second direction DR2. As a result, the precompression that the plurality of balls <NUM> receive from the inner ring <NUM> and the outer ring <NUM> is increased.

It should be clearly understood that the present invention is not limited to the above-described embodiments, that is, the scope of the present invention is defined by the appended claims.

Claim 1:
A rotary shaft locking device (<NUM>, 10A, 10B, 10C, 10D) comprising:
a rotary shaft (<NUM>) comprising a mounting portion (<NUM>) on which a tool (T, T1, T2) is to be mounted and a first contact surface (C1), the rotary shaft (<NUM>) being rotatable about a first axis (AX1);
a first angular contact ball bearing (<NUM>) comprising an inner ring (<NUM>, 31a, 31b) supported by the rotary shaft (<NUM>), an outer ring (<NUM>, 33a, 33b), and a plurality of balls (<NUM>, 35a, 35b) disposed between the inner ring (<NUM>, 31a, 31b) and the outer ring (<NUM>, 33a, 33b); and
a support member (<NUM>) comprising a second contact surface (C2) configured to come into contact with the first contact surface (C1) to lock rotation of the rotary shaft (<NUM>), the support member (<NUM>) rotatably supporting the rotary shaft (<NUM>) through the first angular contact ball bearing (<NUM>);
characterised by
a drive unit (<NUM>) configured to move the rotary shaft (<NUM>) and the inner ring (<NUM>, 31a, 31b) relative to the support member (<NUM>) and the outer ring (<NUM>, 33a, 33b) in a first direction (DR1) parallel to the first axis (AX1) so that the first contact surface (C1) comes into contact with the second contact surface (C2) in order to reduce a precompression that acts on the plurality of balls (<NUM>, 35a, 35b).