Patent ID: 12214465

DESCRIPTION OF EMBODIMENTS

FIG.1toFIG.3show a first embodiment of the present invention. This embodiment deals with a case in which the present invention is applied to a pneumatic work support, by way of example. First of all, the structure of the work support will be described.

An accommodation hole is bored in a table T functioning as a stationary stand, and an internal thread portion is provided on an inner peripheral wall of the accommodation hole. An external thread portion provided on an outer peripheral wall of a housing1is screwed onto the internal thread portion, so that the housing1is fixed to the accommodation hole. The housing1includes: an upper wall (leading end portion)1a; a tubular barrel portion1b; a support member1c; and a lower block1d. The support member1chas a tubular shape and is fixed to a lower portion of a tubular hole of the barrel portion1b. The lower block (base end portion)1dis fixed to a tubular hole of the support member1c. An insertion hole2is provided in an up-down direction through the upper wall1aof the housing1. A support rod3is inserted in the insertion hole2so as to be movable in the up-down direction (toward a leading end side and toward a base end side in an axial direction of the support rod3). The support rod3includes: a tubular rod main body3a; and a push bolt3bscrewed in an upper end portion of the rod main body3a. The rod main body3ahas a tubular hole3cextending in the up-down direction. While in this embodiment, the upper wall1a, the barrel portion1b, the support member1c, and the lower block1dare respectively separable elements, two or three of these elements may be unitary with one another.

A region R to be gripped and held is provided on a lower half portion of an outer peripheral surface of the support rod3, and a tubular collet5is fitted over the region R. The collet5includes: a tapered outer peripheral surface5atapering down upward; and a slit5bextending in the up-down direction. The slit5ballows the collet5to elastically contract. An annular transmission member6is disposed on an outer peripheral side of the collet5. A tapered inner peripheral surface6aof the transmission member6is opposed from above to the tapered outer peripheral surface5aof the collet5. A plurality of balls8are inserted in an annular tapered gap7created between the tapered outer peripheral surface5aand the tapered inner peripheral surface6a. Although the transmission member6and a first piston (piston)12are provided as separate elements in this embodiment, the invention is not limited to this. For example, the transmission member6and the first piston12may be unitary with each other.

A first cylinder10for actuation includes: a first cylinder hole (cylinder hole)11provided in the barrel portion1bof the housing1; the annular first piston (piston)12inserted between the first cylinder hole11and the transmission member6; an actuation chamber13configured to lower the first piston12; and a first spring14configured to raise the first piston12. The first spring14is attached in a spring chamber15provided below the transmission member6.

To be more specific, an upper portion of the first piston12is hermetically guided to the upper wall1aby a sealing member16, while a lower portion of the first piston12is hermetically guided to the support member1cby a sealing member17. When compressed air (compressed gas) is supplied to the actuation chamber13, a downward force is applied to a large annular pressure-receiving surface provided on an upper end portion of the first piston12, while an upward force is applied to a small annular pressure-receiving surface provided on a lower end portion of the first piston12. Due to the difference between the upward and downward forces, the first piston12descends (moves toward the base end side).

The first spring14is structured by a compression coil spring in this embodiment. The first spring14is attached between: an upper spring receiver19attached to an under surface of the transmission member6; and a lower spring receiver20attached to a lower end portion of the collet5. The upper spring receiver19receives the balls8. Furthermore, the first spring14brings a lower end surface of the collet5into contact with the support member1cvia the lower spring receiver20.

A second cylinder21for up-down movement is provided in the tubular hole of the support member1cand in a tubular hole of the lower block1d. The second cylinder21is structured as follows. A second cylinder hole (cylinder hole)22having a large diameter is provided in the tubular hole of the lower block1d. A rod hole23having a diameter smaller than that of the second cylinder hole22is provided in the tubular hole of the support member1c. A second piston25of an output member24is hermetically inserted in the second cylinder hole22via a sealing member25aso as to be movable between its lower limit position (base-end-side limit position) and its upper limit position (leading-end-side limit position) in the up-down direction (in the axial direction of the support rod3). Meanwhile, a piston rod26of the output member24is inserted in the rod hole23. The output member24is inserted in the second cylinder hole22provided in a base end portion of the housing1so as to be movable in the up-down direction (in the axial direction of the support rod3). The output member24is structured by the second piston25and the piston rod26.

In the second cylinder hole22, an inlet chamber29is provided on the base end side in the axial direction of the output member24(in the axial direction of the support rod3). A supply and discharge port30for compressed air is communicatively connected to the inlet chamber29. In the second cylinder hole22, an outlet chamber32is provided on the leading end side in the axial direction of the output member24(in the axial direction of the support rod3). A second spring33configured to move the second piston25downward is attached between an upper wall31of the rod hole23and the second piston25. In this embodiment, the second spring33is structured by a compression coil spring.

A leading end portion of the piston rod26is inserted in the tubular hole3cof the support rod3. A guide groove35is provided on an outer peripheral wall of a leading-end-side portion of the piston rod26so as to extend in the up-down direction. A pin36is attached in a through hole provided through a tubular wall of the support rod3, and the pin36is inserted in the guide groove35. An upper engaging portion35ais provided on an upper end wall of the guide groove35, while a lower engaging portion35bis provided on a lower end wall of the groove35. An upper engaged portion36aconfigured to be engageable with the upper engaging portion35ais provided on an upper wall surface of the pin36. A lower engaged portion36bconfigured to be engageable with the lower engaging portion35bis provided on a lower wall surface of the pin36. An advance spring (biasing means)38configured to bias the support rod3and the piston rod26in respective directions so that they recede from each other is attached between a leading end surface of the piston rod26and a lower end surface of the push bolt3b. The advance spring38of this embodiment is structured by a compression coil spring. In this embodiment, the device is designed so that the size of the outer diameter of the support rod3is substantially equal to the size of the outer diameter of the second piston25. The device is further designed so that the size of the outer diameter of the piston rod26is substantially equal to the size of the inner diameter of the tubular hole3cof the support rod3.

Furthermore, a switching means40, through which one of the inlet chamber29and the outlet chamber32is communicatively connected to the actuation chamber13, is provided at a base-end-side portion of the work support. To be more specific, a communication hole41is bored through a tubular wall of the lower block1d. The communication hole41opens onto a peripheral wall surface of the second cylinder hole22. A passage communicatively connecting the communication hole41to the actuation chamber13is provided in the support member1c. The switching means40is structured by the communication hole41and by an outer peripheral surface of the second piston25(output member24).

Compressed air in the outlet chamber32is discharged to the outside of the housing1through a discharge passage42provided in the housing1. The discharge passage42of this embodiment includes: an annular space created between the piston rod26and the tubular hole of the support member1c; a communication groove3dprovided on a lower end portion of the support rod3; the slit5bof the collet5; an annular space2aprovided between the insertion hole2of the upper wall1aand the support rod3, and the like; and a discharge port42aprovided at a leading end portion of the housing1. A dust seal43is attached to an inner peripheral wall of the insertion hole2of the upper wall1a, that is, at an upper end portion (leading end portion) of the discharge passage42. A lip portion43aof the dust seal43is in close contact with the outer peripheral surface of the support rod3. In this embodiment, an opening/closing valve44is structured by: the dust seal43; and a portion of the outer peripheral surface of the support rod3with which the lip portion43aof the dust seal43is in close contact in a slidable manner. When the pressure of compressed air in the discharge passage42exceeds a predetermined pressure, the compressed air in the discharge passage42causes the lip portion43ato separate from the outer peripheral surface of the support rod3. This opens the opening/closing valve44, and thereby the compressed air in the discharge passage42is discharged through the discharge port42ato the outside of the housing1.

Operations of the work support will be described with reference toFIG.1andFIG.3. In a release state shown inFIG.1, the first piston12and the transmission member6have been raised by the first spring14, and this allows the collet5to expand due to the elastic restoring force of the collet5. Furthermore, the second piston25and the piston rod26have been lowered by the second spring33. Due to this, the piston rod26has lowered the support rod3to its lower limit position against the advance spring38, via the upper engaging portion35aand the upper engaged portion36a.

A workpiece W is brought horizontally to a position above the push bolt3bin the above-described release state.

To cause the work support to transition from the release state ofFIG.1to a lock state ofFIG.3, compressed air is supplied from the supply and discharge port30to the inlet chamber29. As a result, compressed air in the inlet chamber29at first raises the second piston25and the piston rod26against the second spring33. Then, the piston rod26raises the support rod3via the advance spring38. At this time, air in the outlet chamber32is pushed out of the outlet chamber32by the second piston25. In this embodiment, the device is designed so that the amount of air pushed out of the outlet chamber32to an accommodation chamber45, which will be described later, by the second piston25is larger than the capacity of the accommodation chamber45, which is created on the base end side relative to the support rod3when the support rod3is raised from the base-end-side limit position to a leading-end-side position. Due to this, the air pushed out of the outlet chamber32firstly flows into the accommodation chamber45, created between a lower end surface of the support rod3and an upper end surface of the support member1c, and then the amount of air exceeding the capacity of the accommodation chamber45is discharged to the outside of the housing1through the discharge passage42. Thereafter, an upper end surface of the push bolt3bis brought into contact with the workpiece W, as shown inFIG.2.

As the second piston25moves to its upper limit position, the sealing member25aof the second piston25passes over an opening of the communication hole41. As a result, compressed air at the supply and discharge port30passes through the inlet chamber29and the communication hole41in this order and is supplied to the actuation chamber13. When the pressure in the actuation chamber13exceeds a predetermined set pressure (i.e., a pushing force corresponding to the upward biasing force of the first spring14), a force corresponding to the difference between upward and downward pneumatic pressure forces applied from the actuation chamber13to the first piston12acts to the transmission member6. As the downward force of the difference moves the transmission member6downward, the tapered inner peripheral surface6aof the transmission member6is smoothly engaged with the tapered outer peripheral surface5aof the collet5while rolling the balls8downward, with the result that the collet5contracts. Because of this, the collet5with the decreased diameter pushes the region R of the support rod3toward the axis of the support rod3, and thereby grips and holds the support rod3at a height level shown inFIG.3. A top surface of the workpiece W is machined in this lock state and a downward pushing force exerted at the machining process is reliably received from below by virtue of a supporting force of the support rod3.

After the machining process is completed, compressed air in the inlet chamber29is discharged through the supply and discharge port30. As a result, the second piston25and the piston rod26descend at first. Thereafter, the locked support rod3is released. A more detailed description will be given below.

As the compressed air is discharged, first of all, the second piston25and the piston rod26are lowered by the second spring33, and the sealing member25aof the second piston25passes over the opening of the communication hole41. As a result, compressed air in the actuation chamber13is discharged to the outside through the communication hole41, the outlet chamber32, and the discharge passage42. When the pressure in the actuation chamber13becomes lower than the predetermined set pressure, the first piston12and the transmission member6are pushed upward by the first spring14, and the transmission member6moves upward smoothly while rolling the balls8on the tapered inner peripheral surface6a. Consequently, the collet5expands due to its elastic restoring force, to release the locked support rod3. Due to this, the second piston25and the piston rod26descend further, and the piston rod26causes the support rod3to return to its lower limit position shown inFIG.1via the upper engaging portion35aand the upper engaged portion36a.

In the above-described embodiment, the following functions and effects are provided.

In the work support of the above-described embodiment, the discharge passage42includes: the annular space2acreated between the outer peripheral surface of the support rod3and the inner peripheral surface of the insertion hole2of the housing1; and the discharge port42aprovided at the leading end portion of the housing1. When the work support is driven for locking to raise the second piston25, the second piston25pushes air out of the outlet chamber32, and the pushed-out air is supplied to the accommodation chamber45provided below the support rod3. While the support rod3is stopped when brought into contact with a lower surface of a workpiece W, the second piston25is still raised to its upper limit position. As a result, the amount of gas pushed out of the outlet chamber32exceeds the capacity of the accommodation chamber45. The excess amount of gas is therefore discharged, through the annular space2aof the discharge passage42and through a valve-opening clearance of the opening/closing valve44, to the outside of the housing1from the discharge port42a. Meanwhile, when the work support is driven for releasing to lower the first piston12, the first piston12discharges air in the actuation chamber13, through the outlet chamber32, the annular space2a, and the valve-opening clearance of the opening/closing valve44, to the outside of the housing1from the discharge port42a. Due to this, the work support of this embodiment needs neither the ventilation hole in the base end wall, through which air is taken from the outside into the housing or discharged to the outside, nor the passage connected to the ventilation hole and provided in the table, which are provided in the above-described known device. Accordingly, in this embodiment, it is possible to provide a downsized work support with a mechanically simple structure.

As described above, the work support of this embodiment has no ventilation passage, which is provided in the known device. Due to this, the size of the diameter of the lower block1dand the support member1cof the housing1can be reduced by its length. In addition to this, the work support may be arranged as follows, to further downsize the device.

The piston rod26of this embodiment has a cylindrical shape, and has, at a leading end portion thereof, no flange portion which has a diameter larger than that of the piston rod main body and is provided to the piston rod of the known device. This makes it possible to reduce the sizes of the piston rod26and the support rod3in the radial direction. The decrease in the size of the support rod3also reduces the self weight of the support rod3. This allows the second spring33, configured to lower the support rod3and the output member24, to have a smaller width (a less biasing force) and/or a shorter length. This makes it possible to reduce the distance from a top surface of the second piston25to an upper end portion of the support member1c.

In this embodiment, the size of the second piston25is substantially the same as that of the known device, while the support rod3is downsized. As described above, the work support of this embodiment is designed so that: the size of the piston25is substantially equal to the size of the outer diameter of the support rod3; and the maximum stroke of the piston25is equal to the maximum stroke of the support rod3. Furthermore, when the work support is driven for locking, the support rod3is stopped during the stroke (i.e., does not move its maximum stroke) because it comes into contact with the workpiece W. The second piston25moves however its full stroke. Therefore the amount of air pushed out of the outlet chamber32by the second piston25is lager than the capacity of the accommodation chamber45provided below the support rod3. Due to this, the pressure in the discharge passage42during the locking drive becomes higher than that in the release state. When the increasing pressure in the discharge passage42exceeds the predetermined pressure, compressed air in the discharge passage42causes the lip portion43aof the dust seal43of the opening/closing valve44to separate from the outer peripheral surface of the support rod3, and the air is discharged to the outside of the housing1. Although in this embodiment the size of the diameter of the second piston25is designed to be substantially equal to the size of the outer diameter of the support rod3, the size of the diameter of the second piston25may be designed to be larger than the size of the outer diameter of the support rod3. Alternatively, the size of the diameter of the second piston25may be designed to be smaller than the size of the outer diameter of the support rod3. In this case, the full stroke of the second piston25is designed to be longer than the stroke of the support rod3, so that the amount of air pushed out of the outlet chamber32by the second piston25during a locking drive is larger than the increased capacity of the accommodation chamber45created below the support rod3.

FIG.4andFIG.5respectively show a modification of the first embodiment and a second embodiment of the present invention. In the modification of the first embodiment and in the second embodiment, components the same as or similar to the components in the first embodiment are given the same reference numerals, in principle. The following description deals with features different from those in the first embodiment.

The modification of the first embodiment shown inFIG.4is different from the first embodiment in the following points.

In the work support shown inFIG.4, a dust seal51is attached to the insertion hole2bored through the upper wall1aof the housing1. The dust seal51has: a first lip portion51awhich is in close contact with the outer peripheral surface of the support rod3in a slidable manner; and a second lip portion51bwhich is in close contact with an inner peripheral surface of the insertion hole2. A groove-like passage52is provided on a lower wall of the dust seal51so as to extend in the radial direction of the support rod3. The passage52structures a part of the discharge passage42. An opening/closing valve53is provided to the passage52. The opening/closing valve53is structured by: the dust seal51; and the inner peripheral surface of the insertion hole2, with which the second lip portion51bof the dust seal51is in close contact. When the pressure in the discharge passage42exceeds a predetermined pressure, compressed air in the discharge passage42passes through the passage52and through a valve-opening clearance between the second lip portion51bof the dust seal51and the inner peripheral surface of the insertion hole2, and then the compressed air is discharged to the outside of the housing1from the discharge port42a.

In the work support of the first embodiment, the pin36is attached in the through hole provided through the peripheral wall of the support rod3while the guide groove35is provided on the outer peripheral wall of the piston rod26. Instead, in the modification shown inFIG.4, a pin49is provided so as to protrude from the outer peripheral wall of the piston rod26outward in the radial direction of the support rod3, while an elongated hole50is provided in the peripheral wall of the support rod3so as to extend in the up-down direction. The pin49is inserted in the elongated hole50. An upper engaged portion50ais provided on an upper end wall of the elongated hole50. A lower engaged portion50bis provided on a lower end wall of the elongated hole50. An upper engaging portion49aconfigured to be contactable with the upper engaged portion50ais provided on an upper wall surface of the pin49. A lower engaging portion49bconfigured to be contactable with the lower engaged portion50bis provided on a lower wall surface of the pin49.

The second embodiment shown inFIG.5is different from the first embodiment in the following points.

In the second embodiment shown inFIG.5, a biasing means configured to bias the support rod3away from the piston rod26is structured as follows. An attachment groove is provided on an outer peripheral wall of the leading end portion of the piston rod26so as to extend in its circumferential direction, and a sealing member46is attached in the attachment groove. The piston rod26is hermetically inserted in the tubular hole3cof the support rod3so as to be movable in the up-down direction. An air chamber (fluid chamber)54is defined by the tubular hole3cof the support rod3, the piston rod26, and the sealing member46. Due to this, when the piston rod26is moved toward the support rod3, air in the air chamber54is compressed. As a result, the compressed air (air spring) in the air chamber54biases the support rod3upward relative to the piston rod26. In this embodiment, another fluid such as nitrogen may be charged in the fluid chamber54instead of air in the fluid chamber54. In this embodiment, the biasing means configured to bias the support rod3and the output member24so that they recede from each other is structured by the sealing member46and the air chamber54defined by the sealing member46and the like.

A passage47is provided at the leading end portion of the housing1. The passage47communicatively connects the annular space2a, created between the outer peripheral surface of the support rod3and the inner peripheral surface of the insertion hole2provided through the upper wall1a, to the outside of the housing1. The passage47structures a part of the discharge passage42. An opening/closing valve48is provided to an intermediate portion of the passage47, between the upper wall1aand the barrel portion1b. When the pressure of the compressed air in the annular space2aexceeds a predetermined pressure, a rightward pushing force by the pressure of the compressed air moves a ball functioning as a valve element rightward against a leftward biasing force by a valve-closing spring of the opening/closing valve48, thereby to open the opening/closing valve48. When the pressure of the compressed air in the annular space2ais below the predetermined pressure, the ball is engaged with a valve seat by the leftward biasing force by the valve-closing spring, so that the opening/closing valve48is closed.

FIG.6shows a third embodiment. In the third embodiment, components the same as or similar to the components in the first and second embodiments are given the same reference numerals, in principle. The following description deals with features different from those in the first and second embodiments.

An accommodation hole is bored in the table T functioning as a stationary stand and the barrel portion1bof the housing1is inserted and fixed in the accommodation hole. A flange portion1eis provided above the barrel portion1bof the housing1. A supply and discharge port60is provided at the flange portion1e. The supply and discharge port60is communicatively connected to the inlet chamber29through a supply and discharge passage30provided in the housing1. Compressed air from a compressed air source is supplied to the inlet chamber29through the supply and discharge port60and through the supply and discharge passage30.

An inlet passage66, which communicatively connects the tubular hole3cof the rod main body3aof the support rod3to an outside of a leading end portion of the support rod3, is provided in the push bolt3b. An opening/closing valve61is provided to the inlet passage66. The opening/closing valve61is configured to allow a flow of compressed air from the tubular hole3cto the outside of the leading end portion of the support rod3and to block the reverse flow. The valve61is structured as follows, for example.

A tapered valve surface63is provided on a lower end surface of a valve chamber62of the opening/closing valve61. A ball64functioning as a valve element is inserted in the valve chamber62so as to be engageable with the valve surface63and movable in the axial direction of the valve chamber62. In the valve chamber62, a valve-closing spring65is attached between a ceiling surface of the valve chamber62and the ball64. The valve-closing spring65biases the ball64toward the valve surface63. The inlet passage66is communicatively connected to the outside of the work support via an outlet passage67.

The discharge passage42of this embodiment includes the tubular hole3cof the rod main body3aof the support rod3and the inlet passage66, in addition to the above-described annular space2a, the discharge port42aprovided at the leading end portion of the housing1, and the like. Due to this, when the pressure of the compressed air in the discharge passage42exceeds a predetermined pressure, the compressed air in the discharge passage42causes the ball64to separate from the valve surface63. As a result, the opening/closing valve61is opened, and the compressed air in the discharge passage42is discharged to the outside of the work support from a discharge port67a.

The above-described embodiments are changeable as follows.

Instead of compressed air, another type of compressed gas such as compressed nitrogen gas may be used as compressed gas supplied to the inlet chamber29. The driving means configured to move the output member24downward may be an elastic member such as rubber, instead of the second spring33described by way of example.

Instead of the plurality of balls8, a cylindrical element with low friction may be used.

The switching means40is not limited, as long as it is configured to switch between the state in which the actuation chamber13is communicatively connected to the inlet chamber29and the state in which the actuation chamber13is communicatively connected to the outlet chamber32. Accordingly, there may be a moment at which an outer peripheral surface of the second piston25totally closes the opening of the communication hole41. Furthermore, there may be a moment at which the communication hole41communicates with both of the inlet chamber29and the outlet chamber32. It is a matter of course that the switching means40is not limited to the combination of the opening of the communication hole41and the outer peripheral surface of the second piston25.

A throttle passage may be provided to the communication hole41. In this case, the flow resistance in the annular gap between the first cylinder hole11and the first piston12and/or in the communication hole41is increased, and this prolongs the period of time needed to increase/decrease the pressure in the actuation chamber13. This delays the timing at which the first piston12starts to descend/ascend. Thus, the timing at which the first piston12starts locking/releasing the support rod3is delayed, and therefore it is possible to lock/release the support rod3reliably after the piston rod26has been raised/lowered.

The opening/closing valves44,48, and53do not have to be provided. In this case, an end portion of the discharge passage42may be arranged to directly open to the outside of the housing1.

The present disclosure is applicable not only to the work supports having the structures described above by way of example, but also to work supports each having a structure different from those. Furthermore, the present disclosure may be used for applications other than the work supports.

REFERENCE SIGNS LIST

1: housing;1a: upper wall (leading end portion);1d: lower block (base end portion);2: insertion hole;2a: annular space;3: support rod;5: collet;12: first piston (piston);13: actuation chamber;22: second cylinder hole (cylinder hole);24: output member;29: inlet chamber;32: outlet chamber;38: advance spring (biasing means);40: switching means;41: communication hole;42: discharge passage;42a: discharge port;43: dust seal;43a: lip portion;44: opening/closing valve;47: passage;48: opening/closing valve;52: passage;53: opening/closing valve;61: opening/closing valve;66: inlet passage.