Patent Description:
<CIT> (Patent Document <NUM>) discloses an invention related to a linear motor. This linear motor includes a magnetic field unit that functions as a stator and an armature that functions as a mover. The armature has a core, coils, and a cooling pipe. The armature generates driving force associated with electromagnetic induction by application of current to the coils, and moves over the magnetic field unit.

The core is the member that forms the main body of the armature. Housing holes that penetrate in the widthwise direction are formed inside the core. The cooling pipe is routed so as to wind back and forth through the housing holes. As a result, the cooling pipe protrudes from the core in the widthwise direction.

If the cooling pipe protrudes a large amount from the core in the widthwise direction, the size of the linear motor in the widthwise direction increases. Therefore, a technique for reducing the size of the linear motor in the widthwise direction is desired.

According to one example of the present disclosure, there is provided a linear motor for use in a machine tool, as disclosed in appended independent claim <NUM>. The linear motor comprises a magnet plate including a plurality of magnets arranged side by side in a first direction, a slider including a plurality of coils arranged side by side in the first direction, and configured to slide in the first direction relative to the magnet plate, and a cooling pipe provided at a surface portion of the slider on a side opposite to a side facing the magnet plate. The surface portion is provided with a plurality of grooves and a plurality of ridges that alternate in the first direction. The grooves are each elongated in a second direction that is parallel to a surface of the magnet plate and orthogonal to the first direction. The ridges are each elongated in the second direction. The cooling pipe is routed on the slider so as to wind back and forth through the grooves. Each of the ridges has two end portions in the second direction including a first end portion on a side along which a bent portion of the cooling pipe extends, and on at least one side in the second direction, each of the first end portions is entirely located inward of two end faces of the slider in the second direction, or a portion of each of the first end portions, excluding a central portion of the first end portion in the first direction, is located inward of the two end faces of the slider in the second direction.

According to one example of the present disclosure, on both sides in the second direction, each of the first end portions is entirely located inward of the two end faces of the slider in the second direction, or a portion of each of the first end portions, excluding the central portion of the first end portion in the first direction, is located inward of the two end faces of the slider in the second direction.

According to one example of the present disclosure, the two end portions of each of the ridges further include a second end portion on a side along which a bent portion of the cooling pipe does not extend, and the second end portions are each located at the same position as one of the two end faces when viewed in a third direction orthogonal to both the first direction and the second direction.

According to one example of the present disclosure, bent portions of the cooling pipe are located outward of the two end faces when viewed in a third direction orthogonal to both the first direction and the second direction.

According to one example of the present disclosure, end portions of the cooling pipe in the second direction overlap end portions of the coil in the second direction when viewed in a third direction orthogonal to both the first direction and the second direction.

According to one example of the present disclosure, a width of the cooling pipe in the second direction is longer than a width of each of the coils in the second direction.

According to another example of the present disclosure, there is provided a machine tool. The machine tool comprises the linear motor, and a spindle configured to rotatably hold a workpiece or a tool. The linear motor is used to move a position of the spindle.

According to another example of the present disclosure, there is provided a machine tool. the machine tool comprises the linear motor, and a table on which a workpiece is placeable. The linear motor is used to drive the table.

According to another example of the present disclosure, there is provided a machine tool. The machine tool comprises the linear motor, and a loader configured to transport a member. The linear motor is used to drive the loader.

These and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the invention, taken in conjunction with the accompanying drawings.

Hereinafter, each embodiment according to the present invention will be described with reference to the drawings. In the following description, the same parts and constituent elements are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description of these will not be repeated. Note that each embodiment and each modification described below may be selectively combined as appropriate.

First, an overview of a linear motor <NUM> will be described with reference to <FIG> is an oblique perspective view of the linear motor <NUM> according to this embodiment.

As shown in <FIG>, the linear motor <NUM> includes a magnet plate <NUM> and a slider <NUM>.

The magnet plate <NUM> functions as a stator. A plurality of magnets <NUM> are arranged side by side on the magnet plate <NUM>. For convenience in the description, the direction in which the magnets <NUM> are next to each other will hereinafter also be referred to as the X-axis direction (first direction). The direction parallel to the surface of the magnet plate <NUM> and orthogonal to the X-axis direction will also be referred to as the Y-axis direction (second direction). The direction orthogonal to both the X-axis direction and the Y-axis direction will also be referred to as the Z-axis direction (third direction).

The magnets <NUM> are spaced apart by a predetermined gap in the X-axis direction on the magnet plate <NUM>. The magnets <NUM> are each a permanent magnet. The magnets <NUM> are provided on the magnet plate <NUM> such that the polarities of adjacent magnets <NUM> are opposite to each other. For example, assume that the top surface of one magnet <NUM> is the N pole and the bottom surface of that one magnet <NUM> is the S pole. In this case, the magnet <NUM> arranged adjacent to the one magnet <NUM> has an S pole on the top surface and an N pole on the bottom surface.

The slider <NUM> functions as a mover. The slider <NUM> includes a plurality of coils <NUM>. The coils <NUM> are provided side by side in the X-axis direction in the slider <NUM>. The coils <NUM> are wound in an oval shape around later-described teeth <NUM> (see <FIG>) formed in the slider <NUM>.

The coils <NUM> are provided in the slider <NUM> so as to face the magnets <NUM>. In other words, the coils <NUM> are provided in the slider <NUM> so as to overlap the magnets <NUM> when viewed in the Z-axis direction.

When a magnetic field, which is generated by applying alternating current to the coils <NUM>, acts on the magnets <NUM>, the slider <NUM> receives thrust and slides in the X-axis direction over the magnet plate <NUM>. The alternating current is supplied by a power supply (not shown) that is electrically connected to the coils <NUM>, for example.

Next, the aforementioned slider <NUM> will be described in further detail with reference to <FIG>. <FIG> is a diagram illustrating the slider <NUM> from the Z-axis direction. <FIG> is a cross-sectional view of the slider <NUM> taken along line III-III shown in <FIG>. <FIG> is a cross-sectional view of the slider <NUM> taken along line IV-IV shown in <FIG>.

The slider <NUM> includes a housing <NUM> that gives it its appearance. The housing <NUM> is made of resin, for example. A slider core <NUM>, the coils <NUM>, a cooling pipe <NUM>, and fixing members <NUM> are housed in the housing <NUM>.

The slider core <NUM> is constituted by an electromagnetic steel plate, for example. Teeth <NUM> are formed on the slider core <NUM>.

The teeth <NUM> protrude from the lower surface of the slider core <NUM> (i.e., the surface portion on the side facing the magnet plate <NUM>) toward the magnet plate <NUM>. In other words, the teeth <NUM> are formed on the slider core <NUM> so as to face the above-described magnet plate <NUM> and overlap the magnet plate <NUM> when viewed in the Z-axis direction. Moreover, the teeth <NUM> are each elongated in the Y-axis direction.

The teeth <NUM> include auxiliary teeth 53A that are located most outward in the X-axis direction and do not have coils <NUM> wrapped thereon, and coil teeth 53B that are located inward of the auxiliary teeth 53A in the X-axis direction and have coils <NUM> wrapped thereon. The coils <NUM> are wound in an oval shape around the coil teeth 53B.

Through holes H elongated in the Y-axis direction are formed in some of the coil teeth 53B. The fixing members <NUM> are respectively inserted into the through holes H. A threaded hole extending in the Z-axis direction is formed in each of the fixing members <NUM>, and the through holes H in the slider core <NUM> are formed so as to be in communication with the threaded holes of the fixing members <NUM> in the Z-axis direction.

The fixing members <NUM> may have any shape. For example, the fixing members <NUM> may be shaped as a cuboid rectangular bar, a circular column, or any other shape.

The fixing members <NUM> are constituted by a different type of member from the slider core <NUM>. For example, the slider core <NUM> is constituted by a laminated steel plate, and the fixing members <NUM> are formed using a metal other than the metal forming the laminated steel plate. For example, the fixing members <NUM> may be made of iron, or may be made of another type of metal.

The cooling pipe <NUM> is provided on the side opposite to the side that faces the magnet plate <NUM>. The cooling pipe <NUM> has a coolant inlet and a coolant outlet. The inlet and the outlet are connected to a cooler (not shown). The coolant flows from the inlet of the cooling pipe <NUM> to the outlet of the cooling pipe <NUM> and cools the slider <NUM>. Upon reaching the outlet, the coolant is sent to the cooler and cooled. After that, the cooled coolant is sent to the inlet of the cooling pipe <NUM> again. In this manner, the coolant circulates along the upper surface of the slider core <NUM> and absorbs heat from the slider <NUM>. As one example, the coolant is a liquid including water or the like.

The cooling pipe <NUM> is constituted by a metal pipe that has good thermal conductivity, for example. For example, the cooling pipe <NUM> may be made of a copper pipe, an aluminum pipe, or a stainless steel pipe.

Note that although <FIG> illustrates an example in which the cooling pipe <NUM> has a circular cross-sectional shape, the cooling pipe <NUM> may have any cross-sectional shape. The cooling pipe <NUM> may have a polygonal cross-sectional shape, for example, or any other cross-sectional shape.

Next, the aforementioned slider core <NUM> will be described in further detail with reference to <FIG>. <FIG> is a diagram illustrating the slider core <NUM> from the Z-axis direction. <FIG> is a cross-sectional view of the slider core <NUM> taken along line VI-VI shown in <FIG>. <FIG> is a cross-sectional view of the slider core <NUM> taken along line VII-VII shown in <FIG>.

The surface portion of the slider core <NUM> on the side opposite to the side facing the magnet plate <NUM> is provided with grooves G and ridges R that alternate in the X-axis direction.

The grooves G are formed at regular intervals in the X-axis direction. The grooves G are elongated in the Y-axis direction. The cooling pipe <NUM> described above is routed so as to wind back and forth through the grooves G. The length of each groove G in the Y-axis direction is the same as the length of the slider core <NUM> in the Y-axis direction. In other words, when viewed in the Z-axis direction, the two end portions of each groove G in the Y-axis direction are at the same positions as the two end faces of the slider core <NUM> in the Y-axis direction.

Note that although <FIG> shows an example in which the grooves G have a semicircular cross-sectional shape, the grooves G may have any cross-sectional shape. For example, the cross-sectional shape may be polygonal or another shape.

The ridges R are formed at regular intervals in the X-axis direction. The ridges R are elongated in the Y-axis direction. Furthermore, the ridges R protrude from the slider core <NUM> toward the side opposite to the side facing the magnet plate <NUM>. Each of the grooves G is formed by two adjacent ridges R.

In the following description, out of the two end portions of each of the ridges R in the Y-axis direction, the end portion along which a bent portion of the cooling pipe <NUM> extends will also be referred to as an "end portion E1". The bent portions of the cooling pipe <NUM> are each a U-shaped portion that is bent from one side to the other side in the Y-axis direction. Also, out of the two end portions of each of the ridges R in the Y-axis direction, the end portion on the side along which a bent portion of the cooling pipe <NUM> does not extend will be referred to as an "end portion E2". Since the cooling pipe <NUM> winds back and forth along the grooves G, the end portions E1 and E2 alternatingly appear in the X-axis direction.

In the present embodiment, the end portions E1 of the ridges R are located inward of the two end faces of the slider <NUM> in the Y-axis direction. In the example illustrated in <FIG>, the end portions E1 are located at a distance ΔD away from the end faces of the slider <NUM>. Accordingly, the bent portions of the cooling pipe <NUM> can be routed at more inward positions on the slider core <NUM>. As a result, the width of the cooling pipe <NUM> in the Y-axis direction is reduced, and the size of the linear motor <NUM> in the Y-axis direction is reduced.

<FIG> is a diagram in which the cooling pipe <NUM> has been provided on the slider core <NUM> shown in <FIG>. <FIG> is a diagram in which the cooling pipe <NUM> has been provided on a slider core 51X according to a comparative example.

As shown in <FIG>, in the case where the cooling pipe <NUM> is routed on the slider core <NUM> in which the ends of ridges R have been shaved down, the bent portions of the cooling pipe <NUM> can be routed at more inward positions on the slider core <NUM>. As a result, the width of the linear motor <NUM> in the Y-axis direction is "ΔY1".

As shown in <FIG>, in the case where the cooling pipe <NUM> is routed on the slider core 51X in which the ends of the ridges R have not been shaved down, the bent portions of the cooling pipe <NUM> protrude a larger amount from the two end faces of the slider core 51X in the Y-axis direction. As a result, the size of the linear motor <NUM> in the Y-axis direction is "ΔY0". The width "ΔY0" shown in <FIG> is larger than the width "ΔY1" shown in <FIG>.

In this way, the end portions E1 along which the bent portions of the cooling pipe <NUM> extend are formed inward in the slider core <NUM>, and thus the width of the cooling pipe <NUM> in the Y-axis direction is reduced. As a result, the size of the linear motor <NUM> in the Y-axis direction is reduced.

On the other hand, the end portions E2 of the ridges R on the side along which the bent portions of the cooling pipe <NUM> do not extend may be shaved down or may not be shaved down. In the example shown in <FIG>, the end portions E2 are not shaved down. In this case, the end portions E2 of the ridges R are at the same position as one of the end faces of the slider core <NUM> in the Y-axis direction when viewed in the X-axis direction. In other words, the end portions E2 are coplanar with the end face of the slider core <NUM> in the Y-axis direction. By adopting a configuration in which only one end of each of the ridges R is shaved down, the number of shaving locations is reduced.

It is preferable that the effect of cooling the coils <NUM> is maintained when reducing the size of the cooling pipe <NUM> in the Y-axis direction. For example, the cooling pipe <NUM> is routed such that the bent portions are positioned outward of the two end faces of the slider core <NUM> in the Y-axis direction. In other words, the bent portions of the cooling pipe <NUM> are routed so as to protrude from the slider core <NUM> in the Y-axis direction. In this case, the cooling pipe <NUM> is arranged such that the outer peripheral surfaces of the bent portions are located outward of the end faces, and the inner peripheral surfaces of the bent portions are located inward of the end faces.

Also, the coils <NUM> are provided such that the end portions thereof are located outward of the two end faces of the slider core <NUM> in the Y-axis direction. In other words, the coils <NUM> are provided on the slider core <NUM> so as to protrude from the slider core <NUM> in the Y-axis direction. The end portions of the cooling pipe <NUM> in the Y-axis direction (i.e., the bent portions) overlap the end portions of the coils <NUM> in the Y-axis direction when viewed in the Z-axis direction. Accordingly, the cooling pipe <NUM> can cool the end portions of the coils <NUM> as well. As a result, it is possible to suppress deterioration of the performance of the linear motor <NUM> caused by generated heat.

Next, a variation of the above-described slider core <NUM> will be described with reference to <FIG> is a diagram illustrating a slider core 51A according to Variation <NUM> from the Z-axis direction.

The end portions E1 of the ridges R shown in <FIG> are located inward of the end faces of the slider core 51A on both sides in the Y-axis direction. On the other hand, in the slider core 51A according to the present variation, the end portions E1 are located inward of the end faces of the slider core 51A only on one side in the Y-axis direction.

Even in this case, the bent portions on one side of the cooling pipe <NUM> can be routed further inward relative to the slider core <NUM>, and the size of the linear motor <NUM> in the Y-axis direction can be reduced.

Next, another variation of the above-described slider core <NUM> will be described with reference to <FIG> is a diagram illustrating a slider core 51B according to Variation <NUM> from the Z-axis direction.

In the ridges R shown in <FIG> described above, the end portions E2 on the side along which the bent portions of the cooling pipe <NUM> do not extend are not shaved down. On the other hand, in the slider core 51B according to the present variation, the end portions E2 of the ridges R are shaved down.

More specifically, the end portions E2 of the ridges R are located inward of both end faces of the slider <NUM> in the Y-axis direction. It is preferable that the distance ΔD from the end face of the slider core 51B to each of the end portions E2 is equivalent to the distance ΔD from the end face of the slider core 51B to each of the end portions E1. Accordingly, the shape of the slider core 51B is substantially symmetrical with respect to the X-axis. As a result, the operation of linear motor <NUM> is stabilized.

Next, another variation of the above-described slider core <NUM> will be described with reference to <FIG> is a diagram illustrating a slider core 51C according to Variation <NUM> from the Z-axis direction.

The end portions E1 of the ridges R shown in <FIG> described above are entirely located inward of the two end faces of the slider core <NUM> in the Y-axis direction. On the other hand, in the slider core 51C according to the present variation, only a portion of each of the end portions E1 in the X-axis direction is located inward of the two end faces.

More specifically, the central portion of the end portion E1 in the X-axis direction is at the same position as the end face of the slider core <NUM> in the Y-axis direction when viewed in the Z-axis direction. In other words, the central portion is coplanar with the end face of the slider core <NUM> in the Y-axis direction. On the other hand, the remaining portion of the end portion E1 other the central portion is located inward of the two end faces of the slider core <NUM> in the Y-axis direction.

Even if portions other than the central portions of the end portions E1 are shaved down in this way, the bent portions of the cooling pipe <NUM> can be located more inward relative to the slider core <NUM>. As a result, the size of linear motor <NUM> in the Y-axis direction is reduced.

For example, the end portions E1 are chamfered. It is preferable that each of the end portions E1 is R-chamfered such that the outer peripheral surface extends along the inner peripheral surface of the corresponding bent portion of the cooling pipe <NUM>.

Note that the chamfering method for the end portions E1 is not limited to R chamfering, and other chamfering methods may be employed. For example, the end portions E1 may be C-chamfered.

Also, although an example in which the central portions of the end portions E1 are coplanar with the end face of the slider core <NUM> is illustrated in <FIG>, the chamfered end portions E1 may be entirely located inward of the two end faces of the slider core <NUM> in the Y-axis direction.

As described above, the end portions E1 of the ridges R are shaved down by the distance ΔD (see <FIG>) from the two end faces of the slider <NUM> in the Y-axis direction so as to be located inward of the end faces. Preferable values of the distance ΔD will be described below with reference to <FIG> and <FIG>.

<FIG> is a diagram illustrating the above-described cooling pipe <NUM> from the Z-axis direction. <FIG> is a diagram illustrating a coil <NUM> wound around a tooth <NUM> from the Z-axis direction.

As shown in <FIG>, "S" denotes the length of the straight portion of the cooling pipe <NUM> in the Y-axis direction. Also, "X" denotes the length of the portions of the cooling pipe <NUM> other than the straight portion. In this case, the total length of the cooling pipe <NUM> in the Y-axis direction is "S+X".

As shown in <FIG>, "L" denotes the length of the slider core <NUM> in the Y-axis direction is. Here, "L" corresponds to the laminated thickness of the slider core <NUM>. Also, "E" denotes the distance of separation between the tooth <NUM> and the coil <NUM> in the Y-axis direction. Furthermore, "L" denotes the length of the slider core <NUM> in the Y-axis direction. Also, "A" denotes the width of the end portion of the coil <NUM> in the Y-axis direction.

In order for the cooling pipe <NUM> to sufficiently cool the coil <NUM>, it is preferable that the width of the cooling pipe <NUM> in the Y-axis direction is longer than the width of the coil <NUM> in the Y-axis direction. For this reason, it is preferable that the total length "S+X" of the cooling pipe <NUM> in the Y-axis direction satisfies the following Expression <NUM>.

Also, the aforementioned distance ΔD, which corresponds to the ridge R shaving amount, is represented by Expression <NUM> shown below.

According to Expressions <NUM> and <NUM> above, it is preferable that the distance ΔD satisfies Expression <NUM> shown below.

Accordingly, the width of the cooling pipe <NUM> in the Y-axis direction is longer than the width of each of the coils <NUM> in the Y-axis direction. Also, the cooling pipe <NUM> is shorter by the distance ΔD in the Y-axis direction. As a result, the size of the linear motor <NUM> in the Y-axis direction is reduced while also maintaining the ability of the cooling pipe <NUM> to cool the coil <NUM>.

Next, application examples of the above-described linear motor <NUM> will be described with reference to <FIG>. The linear motor <NUM> can be used to drive various parts in a machine tool, for example.

The term "machine tool" as used herein is a concept that includes various devices that have the function of machining a workpiece. The machine tool <NUM> may be a horizontal machining center or a vertical machining center. Alternatively, the machine tool <NUM> may be a lathe, an additive processing machine, or another cutting or grinding machine.

In the case where the linear motor <NUM> is used in a machine tool, the magnet plate <NUM>, which functions as a stator, is attached to a stationary part in the machine tool. On the other hand, the slider <NUM>, which functions as a mover, is attached to a part that is to be driven in the machine tool. In this case, bolts are inserted through the part to be driven, and the bolts are screwed into the threaded holes formed in the fixing members <NUM> formed in the slider <NUM>. Accordingly, the part to be driven is fixed to the slider <NUM>.

First, an example in which the linear motor <NUM> is applied to the driving of a spindle will be described with reference to <FIG> is a diagram illustrating an example of the configuration of a machine tool <NUM>.

The linear motor <NUM> is used to move the position of a spindle <NUM> for rotatably holding a workpiece or a tool, for example. The spindle <NUM> may be a work spindle for rotating a workpiece, or may be a tool spindle for rotating a tool.

For convenience in the description, the coordinate system based on the spindle <NUM> is hereinafter represented by an X' axis, a Y' axis, and a Z' axis. The X' axis, the Y' axis, and the Z' axis are orthogonal to each other.

As shown in <FIG>, the machine tool <NUM> includes a control unit 200A, a drive unit 240A, and the spindle <NUM>.

The control unit 200A is a CNC (Computer Numerical Control) device, for example. The CNC device includes at least one integrated circuit. For example, the integrated circuit is at least one CPU (Central Processing Unit), at least one MPU (Micro Processing Unit), at least one ASIC (Application Specific Integrated Circuit), at least one FPGA (Field Programmable Gate Array), or any combination thereof. The control unit 200A controls the operation of the drive unit 240A by executing various programs such as a machining program.

The drive unit 240A is a mechanism for driving the spindle <NUM>. The drive unit 240A may have any device configuration. The drive unit 240A may be constituted by a single drive unit, or may be constituted by a plurality of drive units. In the example of <FIG>, the drive unit 240A is constituted by motor drivers 241A to 241C, linear motors 242A to 242C, and encoders 243A to 243C. The linear motors 242A to 242C each correspond to the linear motor <NUM> described above.

The motor driver 241A controls the driving of the spindle <NUM> in the X' axis direction. The motor driver 241A receives a control signal from the control unit 200A and outputs a current that corresponds to the control signal to the linear motor 242A.

More specifically, the control unit 200A sequentially outputs control signals that include a target position to the motor driver 241A. The motor driver 241A calculates the actual position of the spindle <NUM> based on a feedback signal from the encoder 243A, and outputs a current that reduces the difference between the actual position and the target position to the linear motor 242A. Accordingly, the motor driver 241A moves the spindle <NUM> to a desired position in the X' axis direction.

The motor driver 241B controls the driving of the spindle <NUM> in the Y' axis direction. The motor driver 241B receives a control signal from the control unit 200A and outputs a current that corresponds to the control signal to the linear motor 242B.

More specifically, the control unit 200A sequentially outputs control signals that include a target position to the motor driver 241B. The motor driver 241B calculates the actual position of the spindle <NUM> based on a feedback signal from the encoder 243B, and outputs a current that reduces the difference between the actual position and the target position to the linear motor 242B. Accordingly, the motor driver 241B moves the spindle <NUM> to a desired position in the Y' axis direction.

The motor driver 241C controls the driving of the spindle <NUM> in the Z' axis direction. The motor driver 241C receives a control signal from the control unit 200A and outputs a current that corresponds to the control signal to the linear motor 242C.

More specifically, the control unit 200A sequentially outputs control signals that include a target position to the motor driver 241C. The motor driver 241C calculates the actual position of the spindle <NUM> based on a feedback signal from the encoder 243C, and outputs a current that reduces the difference between the actual position and the target position to the linear motor 242C. Accordingly, the motor driver 241C moves the spindle <NUM> to a desired position in the Z' axis direction.

Next, an example in which the linear motor <NUM> is applied to the driving of a table will be described with reference to <FIG> is a diagram illustrating another example of the configuration of a machine tool <NUM>.

The linear motor <NUM> is used to drive a table <NUM> provided in a machine tool, for example. The table <NUM> is a stand for placement of a workpiece to be subjected to machining.

As shown in <FIG>, the machine tool <NUM> includes a control unit 200A, a drive unit 240B, and the table <NUM>.

The drive unit 240B is a mechanism for driving the table <NUM>. The drive unit 240B may have any device configuration. The drive unit 240B may be constituted by a single drive unit, or may be constituted by a plurality of drive units. In the example of <FIG>, the drive unit 240B is constituted by motor drivers 241D, 241E, linear motors 242D, 242E, and encoders 243D, 243E. The linear motors 242D, 242E each correspond to the linear motor <NUM> described above.

The motor driver 241D controls the driving of the table <NUM> in the X' axis direction. The motor driver 241D receives a control signal from the control unit 200A and outputs a current that corresponds to the control signal to the linear motor 242D.

More specifically, the control unit 200A sequentially outputs control signals that include a target position to the motor driver 241D. The motor driver 241D calculates the actual position of the table <NUM> based on a feedback signal from the encoder 243D, and outputs a current that reduces the difference between the actual position and the target position to the linear motor 242D. Accordingly, the motor driver 241D moves the table <NUM> to a desired position in the X' axis direction.

The motor driver 241E controls the driving of the table <NUM> in the Y' axis direction. The motor driver 241E receives a control signal from the control unit 200A and outputs a current that corresponds to the control signal to the linear motor 242E.

More specifically, the control unit 200A sequentially outputs control signals that include a target position to the motor driver 241E. The motor driver 241E calculates the actual position of the table <NUM> based on a feedback signal from the encoder 243E, and outputs a current that reduces the difference between the actual position and the target position to the linear motor 242E. Accordingly, the motor driver 241E moves the table <NUM> to a desired position in the Y' axis direction.

Next, an example in which the linear motor <NUM> is applied to the driving of a loader will be described with reference to <FIG> is a diagram illustrating another example of the configuration of a machine tool <NUM>.

The linear motor <NUM> is used to drive a loader <NUM> for transporting a member, for example. The member may be a workpiece that has not yet been subjected to machining, a machined workpiece, or a tool.

As shown in <FIG>, the machine tool <NUM> includes a control unit 200A, a drive unit 240C, and the loader <NUM>.

The drive unit 240C is a mechanism for driving the loader <NUM>. The drive unit 240C may have any device configuration. The drive unit 240C may be constituted by a single drive unit, or may be constituted by a plurality of drive units. In the example of <FIG>, the drive unit 240C is constituted by motor drivers 241F, <NUM>, <NUM>, linear motors 242F, <NUM>, <NUM>, and encoders 243F, <NUM>, <NUM>. The linear motors 242F, <NUM>, <NUM> each correspond to the linear motor <NUM> described above.

The motor driver 241F controls the driving of the loader <NUM> in the X' axis direction. The motor driver 241F receives a control signal from the control unit 200A and outputs a current that corresponds to the control signal to the linear motor 242F.

More specifically, the control unit 200A sequentially outputs control signals that include a target position to the motor driver 241F. The motor driver 241F calculates the actual position of the loader <NUM> based on a feedback signal from the encoder 243F, and outputs a current that reduces the difference between the actual position and the target position to the linear motor 242F. Accordingly, the motor driver 241F moves the loader <NUM> to a desired position in the X' axis direction.

The motor driver <NUM> controls the driving of the loader <NUM> in the Y' axis direction. The motor driver <NUM> receives a control signal from the control unit 200A and outputs a current that corresponds to the control signal to the linear motor <NUM>.

More specifically, the control unit 200A sequentially outputs control signals that include a target position to the motor driver <NUM>. The motor driver <NUM> calculates the actual position of the loader <NUM> based on a feedback signal from the encoder <NUM>, and outputs a current that reduces the difference between the actual position and the target position to the linear motor <NUM>. Accordingly, the motor driver <NUM> moves the loader <NUM> to a desired position in the Y' axis direction.

The motor driver <NUM> controls the driving of the loader <NUM> in the Z' axis direction. The motor driver <NUM> receives a control signal from the control unit 200A and outputs a current that corresponds to the control signal to the linear motor <NUM>.

More specifically, the control unit 200A sequentially outputs control signals that include a target position to the motor driver <NUM>. The motor driver <NUM> calculates the actual position of the loader <NUM> based on a feedback signal from the encoder <NUM>, and outputs a current that reduces the difference between the actual position and the target position to the linear motor <NUM>. Accordingly, the motor driver <NUM> moves the loader <NUM> to a desired position in the Z' axis direction.

The embodiment disclosed this time is an example in all respects and should be considered to be not restrictive. The scope of the present invention is defined not by the description above but by the claims.

Claim 1:
A linear motor (242A) for use in a machine tool, the linear motor (242A) comprising
a magnet plate (<NUM>) including a plurality of magnets (<NUM>) arranged side by side in a first direction;
a slider (<NUM>) including a plurality of coils (<NUM>) arranged side by side in the first direction, and configured to slide in the first direction relative to the magnet plate (<NUM>); and
a cooling pipe (<NUM>) provided at a surface portion of the slider (<NUM>) on a side opposite to a side facing the magnet plate (<NUM>),
wherein the surface portion is provided with a plurality of grooves (G) and a plurality of ridges (R) that alternate in the first direction,
the grooves (G) are each elongated in a second direction that is parallel to a surface of the magnet plate (<NUM>) and orthogonal to the first direction,
the ridges (R) are each elongated in the second direction,
the cooling pipe (<NUM>) is routed on the slider (<NUM>) so as to wind back and forth through the grooves (G),
each of the ridges (R) has two end portions (E1) in the second direction including a first end portion (E1) on a side along which a bent portion of the cooling pipe (<NUM>) extends,
characterized in that
on at least one side in the second direction, each of the first end portions (E1) is entirely located inward of two end faces of the slider (<NUM>) in the second direction, or a portion of each of the first end portions (E1), excluding a central portion of the first end portion (E1) in the first direction, is located inward of the two end faces of the slider (<NUM>) in the second direction.