Positioning apparatus and clamping system having the same

A plug member (12) inserted into a positioning hole (5) formed in a second block (2) is projected from a first block (1). A plurality of slide portions (61) opposed to each other across the plug member (12) are arranged around the plug member (12) movably in a first radial direction (D1) substantially orthogonal to the opposed direction thereof. A first pressing member (15) and a second pressing member (19) are arranged outside the slide portions (61) diametrically expandably and diametrically contractibly and axially movably. The first pressing member (15) is driven toward a base end by a drive device, whereby the slide portions (61) expand the first pressing member (15) via the second pressing member (19), thereby the slide portions (61) are moved in the first radial direction (D1) with respect to the plug member (12). After the movement, when the second pressing member (19) is blocked from moving toward the base end, the first pressing member (15) strongly presses an inner peripheral surface of the positioning hole (5) in the second radial direction (D2).

TECHNICAL FIELD

The present invention relates to an apparatus for positioning a second block such as a work pallet with respect to a first block such as a table of a machine tool, also relates to a clamping system equipped with the positioning apparatus.

BACKGROUND OF THE INVENTION

Such a positioning apparatus is in general conventionally constructed so as to fit a plug projected from a support surface of a reference member (first block) into a circular positioning hole opened on a supported surface of a movable member (second block) (for example, refer to the following Patent Document 1).Patent Document 1: Japanese Unexamined Patent Publication No. 57-27640

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

In the above-described prior art, it is necessary to provide a predetermined fitting gap between the positioning hole and the plug in order to attain a smooth fitting of them. Thereby, the gap will result in a decreased positioning accuracy.

The present invention has been made in view of the above problem, an object of which is to provide a positioning apparatus capable of conducting positioning with high accuracy.

Means for Solving the Problem and Effect

The problem to be solved by the present invention is as described above. Next, an explanation will be made for the means for solving the problem and the effect.

A positioning apparatus of a first invention is constructed as follows as illustrated inFIG. 1throughFIG. 3,FIG. 10orFIG. 11for example.

A plug member12inserted into a positioning hole5formed in a second block2is projected from a first block1. A plurality of slide portions61,61opposed to each other across the plug member12are arranged around the plug member12movably in a first radial direction D1substantially orthogonal to the opposed direction thereof. A first pressing member15is arranged outside the slide portions61,61diametrically expandably and diametrically contractibly and axially movably within a predetermined range. A second pressing member19is arranged outside the slide portions61,61and inside the first pressing member15diametrically expandably and diametrically contractibly and axially movably within a predetermined range. The first pressing member15or the second pressing member19is driven toward a base end by a drive means D, whereby the slide portions61,61expand the first pressing member15in a second radial direction D2different from the first radial direction D1, thereby the slide portions61,61are moved in the first radial direction D1with respect to the plug member12.

According to the first invention, after the first pressing member15is inserted into the positioning hole5, the fitting gap G (for example, refer toFIG. 4andFIG. 5) can be eliminated by the drive means D to conduct positioning. Therefore, the first pressing member is smoothly inserted into the positioning hole and also positioned with high accuracy. Further, positioning with high accuracy can be conducted in the second radial direction, and positional misalignment of the positioning hole to the plug member in the first radial direction is allowed, because the slide portions slide. When the first pressing member or the second pressing member whose axial movement is allowed within a predetermined range is prevented from moving toward the base end, the first pressing member is allowed to strongly press an inner peripheral surface of the positioning hole, thereby making it possible to accomplish positioning in the second radial direction with high accuracy.

In the first invention, it is preferable to provide the following construction, for example, as illustrated inFIG. 1throughFIG. 3,FIG. 10orFIG. 11.

An inclined outer surface13is formed on the second pressing member19. An inclined inner surface17allowed to make a tapering engagement with the inclined outer surface13is formed on the first pressing member15. A drive member21is inserted into the plug member12axially movably, and the drive member21is connected to the first pressing member15or the second pressing member19. The first pressing member15or the second pressing member19is moved toward the base end for locking via the drive member21so as to expand the first pressing member15in the second radial direction D2by the tapering engagement and bring the first pressing member15into close contact with an inner peripheral surface of the positioning hole5. The first pressing member15or the second pressing member19is moved toward a leading end for releasing via the drive member21so as to cancel the diametrically expanded condition of the first pressing member15and cancel the closely contacted condition.

According to the second invention, the second block is allowed to be positioned in the second radial direction with respect to the first block reliably and strongly by diametrically expanding force applied by the tapering engagement. Further, when the drive member is driven to move the first pressing member or the second pressing member for locking, the second block is allowed to be pressed against the first block via the first pressing member, thereby making it possible to omit an exclusive clamping means.

In the first invention, it is preferable to provide the following construction, for example, as illustrated inFIG. 1throughFIG. 3,FIG. 10orFIG. 11.

An advancing means69which advances the first pressing member15or the second pressing member19toward a leading end is provided.

According to the third invention, during the locking movement, the first pressing member (or the second pressing member) attempts to move the second pressing member (or the first pressing member) toward a base end, to which the advancing means resists. Therefore, the first pressing member is smoothly expanded in a diametrically expanding direction. Further, the first pressing member which is in close contact with the positioning hole is allowed to move toward the base end against the advancing means by the diametrical expansion, thereby making it possible to strongly clamp the second block with respect to the first block.

A positioning apparatus of a fourth invention is constructed as follows, for example, as illustrated inFIG. 12andFIG. 13,FIG. 14,FIG. 15andFIG. 16, orFIG. 19.

A plug member12inserted into a positioning hole5formed in a second block2is projected from a first block1. A plurality of slide portions61,61opposed to each other across the plug member12are arranged around the plug member12movably in a first radial direction D1substantially orthogonal to the opposed direction thereof and axially movably within a predetermined stroke. A pressing member15is arranged outside the slide portions61,61diametrically expandably and diametrically contractibly and axially movably. The pressing member15is driven toward a base end by a drive means D, whereby the slide portions61,61diametrically expand the pressing member15in a second radial direction D2different from the first radial direction D1, thereby the slide portions61,61are moved in the first radial direction D1with respect to the plug member12.

According to the fourth invention, after the pressing member15is inserted into the positioning hole5, the fitting gap G (for example, refer toFIG. 12andFIG. 13) is allowed to be eliminated by the drive means D to conduct positioning. Therefore, the pressing member is smoothly inserted into the positioning hole and also positioned with high accuracy. Further, positioning with high accuracy can be conducted in the second radial direction, and positional misalignment of the positioning hole to the plug member in the first radial direction is allowed, because the slide portions slide. It is noted that, when the slide portions whose axial movement is allowed within a predetermined stroke is prevented from moving toward the base end, the pressing member is allowed to strongly press an inner peripheral surface of the positioning hole, thereby making it possible to accomplish positioning in the second radial direction with high accuracy.

In the fourth invention, it is preferable to provide the following construction, for example, as illustrated inFIG. 12andFIG. 13,FIG. 14,FIG. 15andFIG. 16, orFIG. 19.

Inclined outer surfaces13are formed on the slide portions61,61. An inclined inner surface17allowed to make a tapering engagement with the inclined outer surfaces13is formed on the pressing member15. A drive member21is inserted into the plug member12axially movably, and the drive member21is connected to the pressing member15. The drive member21moves the pressing member15toward the base end for locking to expand the pressing member15in the second radial direction D2by the tapering engagement and bring the pressing member15into close contact with an inner peripheral surface of the positioning hole5. The drive member21moves the pressing member15toward a leading end for releasing to cancel the diametrically expanded condition of the pressing member15and cancel the closely contacted condition.

According to the fifth invention, it is possible to position the second block with respect to the first block in the second radial direction reliably and strongly by diametrically expanding force applied from the tapering engagement. Further, when the drive member is driven to move the pressing member for locking, the second block is allowed to be pressed against the first block via the pressing member, thereby making it possible also to omit an exclusive clamping means.

In the fourth invention, it is preferable to provide an advancing means69which advances the slide portions61,61toward a leading end, for example, as illustrated inFIG. 12andFIG. 13,FIG. 14,FIG. 15andFIG. 16, orFIG. 19.

According to the sixth invention, during the locking movement, the pressing member attempts to move the slide portions toward the base end, to which the advancing means resists. Therefore, the pressing member is smoothly expanded diametrically. Further, by moving the pressing member which is in close contact with the positioning hole by the diametrical expansion toward the base end against the advancing means, it is possible to strongly clamp the second block with respect to the first block.

In the first invention or in the fourth invention, it is preferable that the first pressing member or pressing member15is formed into an annular shape, for example, as illustrated inFIG. 1throughFIG. 3,FIG. 10,FIG. 11,FIG. 12andFIG. 13, orFIG. 14.

According to the seventh invention, it is structurally possible to prevent intrusion of foreign matter inside the first pressing member (or the pressing member) and also avoid troubles on the positioning apparatus resulting from the foreign matter.

In the seventh invention, it is preferable to provide the following construction, for example, as illustrated inFIG. 1throughFIG. 3,FIG. 10,FIG. 11,FIG. 12andFIG. 13, orFIG. 14.

A slit51is formed in the first pressing member or pressing member15, and the first pressing member or the pressing member15is allowed to deform in a diametrically expanding direction and a diametrically contracting direction by existence of the slit51.

According to the eighth invention, such a mechanically simple construction is accomplished that the first pressing member (or the pressing member) is allowed to be deformed in a diametrically expanding direction and a diametrically contracting direction. Further, the first pressing member (or the pressing member) is allowed to be deformed to a larger amount in a radial direction, thereby making the fitting gap larger to smoothly insert the first pressing member (or the pressing member) into the positioning hole.

In the first invention, it is preferable that the second pressing member19is formed into an annular shape, for example, as illustrated inFIG. 1throughFIG. 3,FIG. 10, orFIG. 11.

According to the ninth invention, it is structurally possible to prevent intrusion of foreign matter inside the second pressing member and also avoid troubles on the positioning apparatus resulting from the foreign matter.

In the ninth invention, it is preferable to provide the following construction, for example, as illustrated inFIG. 1throughFIG. 3,FIG. 10, orFIG. 11.

A slit57is formed in the second pressing member19, and the second pressing member19is allowed to deform in a diametrically expanding direction and a diametrically contracting direction by existence of the slit57.

According to the ninth invention, such a simple construction is accomplished that the second pressing member is allowed to deform in a diametrically expanding direction and a diametrically contracting direction.

In the ninth invention, it is preferable to provide the following construction, for example, as illustrated inFIG. 1throughFIG. 3.

Gaps A, A are formed between the second pressing member19and the plug member12in the first radial direction D1.

According to the eleventh invention, the first pressing member and second pressing member are movable in the first radial direction so as to smoothly absorb positional misalignment in the first radial direction occurring between the positioning hole and the plug member.

In the first invention or the fourth invention, it is preferable to provide the following construction, for example, as illustrated inFIG. 15andFIG. 16, orFIG. 19.

The first pressing member or the pressing member15is formed into a block shape and arranged so as to oppose each other across the slide portions61,61in plurality.

According to the twelfth invention, the first pressing member (or the pressing member) does not deform in a diametrically expanding direction (the second radial direction) but simply undergoes a displacement to press the inner peripheral surface of the positioning hole. Therefore, the first pressing member (or the pressing member) is deformed to a larger range and allowed to be inserted into the positioning hole more smoothly.

In the twelfth invention, it is preferable to provide the following construction, for example, as illustrated inFIG. 18.

Two contact portions61a,61aallowed to come into contact with an inner surface of the first pressing member or pressing member15and escape portion61barranged between the two contact portions61a,61aare formed on an outer surface of each of the slide portions61circumferentially side by side. A gap C is formed between the escape portion61band the first pressing member or pressing member15.

According to the thirteenth invention, the inner surface of the first pressing member (or the pressing member) is pushed at two contact portions for each of the slide portions but not pushed at the escape portion. Therefore, the inner surface of the first pressing member (or the pressing member) is brought into contact at two contact portions for one slide portion and, during the locking movement, the first pressing member (or the pressing member) is allowed to receive reaction force applied from the inner peripheral surface of the positioning hole at the two portions stably. It is, therefore, possible to correct appropriately and reliably positional misalignment in the second radial direction occurring between the positioning hole and the plug member.

In the twelfth invention, it is preferable to provide the following construction, for example, as illustrated inFIG. 18.

Two contact portions15a,15aand an escape portion15barranged between the two contact portions15a,15aare formed on an outer surface of each of the first pressing member or pressing member15circumferentially side by side. When the contact portions15a,15acome into contact with an inner peripheral surface of the positioning hole5, a gap B is formed between the escape portion15band the inner peripheral surface of the positioning hole5.

According to the fourteenth invention, the first pressing member (or the pressing member) is allowed to be appropriately positioned even in a case where the positioning hole has a larger inner diameter and the first pressing member (or the pressing member) is required to undergo a larger displacement so as to come into close contact with the inner peripheral surface of the positioning hole. Namely, the inner peripheral surface of the positioning hole is pushed at two contact portions for each of the first pressing members (or the pressing member), whereas not pushed at the escape portion. Therefore, diametrically expanding force (force in the second radial direction) is applied at two contact portions each for one first pressing member (or one pressing member) to correct positional misalignment in the second radial direction occurring between the positioning hole and the plug member appropriately and reliably.

In the twelfth invention, it is preferable to provide the following construction, for example, as illustrated inFIG. 15andFIG. 16, orFIG. 19.

A cylindrical connecting member81is arranged around an outer periphery of the plug member12. The first pressing member or pressing member15is supported on the connecting member81movably in the second radial direction D2.

According to the fifteenth invention, a simple construction is realized for supporting the first pressing member (or the pressing member) formed into a block shape. Further, the connecting member is driven by a drive means, by which the first pressing member (or the pressing member) is allowed to be easily moved for locking or releasing. In addition, the connecting member is formed into a cylindrical shape, thereby a construction is provided that intrusion of foreign matter inside of the connecting member is made difficult.

In the twelfth invention, it is preferable that a returning member84which applies diametrically contracting force to the first pressing member or pressing member15is provided, for example, as illustrated inFIG. 15andFIG. 16, orFIG. 19.

According to the sixteenth invention, the first pressing member (or the pressing member) formed into a block shape is allowed to easily return to a non diametrically-expanded condition.

In the first invention or the fourth invention, it is preferable to provide the following construction, for example, as illustrated inFIG. 2,FIG. 10,FIG. 11,FIG. 12,FIG. 14, orFIG. 15.

The drive means D moves the second block2toward a base end via the first pressing member or pressing member15in such a condition that the first pressing member or pressing member15comes into close contact with an inner peripheral surface of the positioning hole5, and presses a supported surface2aof the second block2against a support surface1aof the first block1.

According to the seventeenth invention, the second block is allowed to be positioned in the second radial direction with respect to the first block and also to be restricted in the axial direction.

The clamping system of the present invention is provided with the clamping apparatus set forth in the first invention or the fourth invention.

According to the eighteenth invention, workability when attaching or detaching the first block and the second block is excellent and positioning can be conducted with high accuracy.

The clamping system of the present invention is constructed in such a way that a plurality of positioning apparatuses are provided, and at least one of them is the positioning apparatus as set forth in the first invention or the fourth invention.

According to the nineteenth invention, workability when attaching or detaching the first block and the second block is excellent and positioning can be conducted with high accuracy. Further, a clamping system which is allowed to conduct positioning in various modes is provided.

DESCRIPTION OF REFERENCE NUMERALS

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment

FIG. 1throughFIG. 8illustrate a first embodiment of the present invention.

First, an explanation will be made for a whole structure of a positioning apparatus of the present invention by referring toFIG. 1throughFIG. 3.FIG. 1is a plan view of a plug means of the positioning apparatus.FIG. 2is a view indicated by the arrow2-2inFIG. 1.FIG. 3is a cross sectional view indicated by the arrow3-3inFIG. 2.

In the present embodiment, as illustrated inFIG. 2, a base plate1as a first block is placed and fixed to a table T of a machine tool. In the work pallet2as a second block is opened a circular positioning hole5in a penetrating manner. Corresponding to the positioning hole5, on the base plate1is provided a plug means6.

Hereinafter, an explanation will be made for construction of the plug means6.

As illustrated inFIG. 2, in an upper surface of the base plate1is formed an installation hole8. A housing9is fitted into the installation hole8in a precisely positioned condition. A flange9aof the housing9is fixed to the base plate1by a plurality of tightening bolts10(refer toFIG. 1).

A plug member12is projected from the housing9upward (toward a leading end). The plug member12is allowed to be inserted into the positioning hole5. An axis of the plug member12coincides with an axis of the installation hole8.

On a periphery of the plug member12are projected a plurality of bosses1b(in the present embodiment, four bosses1bas illustrated inFIG. 1) from the flange9aupward. On an upper end surface of the boss1bis formed a flat support surface1a. The positioning apparatus of the present embodiment is constructed in such a way that a supported surface2aof the work pallet2as the second block is received by the support surface1aof the base plate1and the work pallet2is positioned with respect to the base plate1.

On an outer periphery of the plug member12is formed a pair of slide outer surfaces64,64facing each other in a radical direction. The slide outer surfaces64,64are formed into a vertical flat surface which is parallel to the axis of the plug member12.

Outside the plug member12are provided a pair of slide portions61,61. The slide portions61,61are arranged so as to oppose each other across the plug member12in a radial direction.

On inner surfaces of the respective slide portions61,61are formed slide surfaces63,63. The slide surface63is also formed into a vertical flat surface which is parallel to the axis of the plug member12, as with the slide outer surface64. The slide portions61,61are arranged in such a way that the slide surfaces63,63come into contact with the slide outer surfaces64,64, and allowed to move toward a first radial direction (first diametrically direction) D1given inFIG. 3, along the slide surfaces63,63. Additionally, outer surfaces of the respective slide portions61,61are formed into an arc surface which is made straight vertically (straight outer surface).

An annular wedge member19(second pressing member) is arranged outside the slide portions61,61and around an outer periphery of the plug member12. An inner surface of the wedge member19comes into contact with the straight outer surface of the slide portions61,61. The inner surface of the wedge member19slides on the straight outer surface, by which the wedge member19is allowed to move axially within a predetermined movable stroke to be described later.

As illustrated inFIG. 3and others, the wedge member19is formed into a collet shape. Namely, on a peripheral wall19aof the wedge member19is provided one slit57extending axially and opened on both upper and lower ends. Thereby, a substantially whole part of the peripheral wall19awhich extends circumferentially is allowed to undergo an elastic deformation in a diametrically expanding direction and a diametrically contracting direction.

Further, over an entire outer periphery of the wedge member19is formed an inclined outer surface13. The inclined outer surface13is constructed into a tapered shape so as to get closer to the axis upward (toward the leading end).

Additionally, between the wedge member19and the plug member12are formed gaps A, A in the first radial direction D1, as illustrated inFIG. 3.

Outside the wedge member19is arranged an annular sleeve member (first pressing member)15. The sleeve member15is also formed into a collet shape, as with the wedge member19. Namely, on a peripheral wall15aof the sleeve member15is provided one slit51extending axially and opened on both upper and lower ends. Thereby, a substantially whole part of the peripheral wall19awhich extends circumferentially is allowed to undergo an elastic deformation in a diametrically expanding direction and a diametrically contracting direction. In addition, when the sleeve member15is released for diametrically expanding force thereof, the sleeve member15is allowed to return to a diametrically contracting direction by its own elastic restoring force.

Over an entire inner periphery of the sleeve member15is formed an inclined inner surface17. The inclined inner surface17is formed into a tapered shape so as to get closer to the axis upward (toward the leading end). The inclined inner surface17is allowed to make a tapering engagement with the inclined outer surface13of the wedge member19.

Over an entire outer periphery of the sleeve member15is formed a straight outer surface16, which is allowed to come into close contact with the positioning hole5.

In the sleeve member15, the slit51is not limited to a single slit but may be available in plurality. For example, the slits51may be opened on both the upper and lower ends of the sleeve member15alternately and circumferentially. Similarly, in the wedge member19, the slit57is not limited to a single slit but may be available in plurality.

A rotation stopper pin52is fixed to the wedge member19, and an outer end of the rotation stopper pin52projecting in a radial direction is inserted into the slit51of the sleeve member15. Consequently, rotation of the sleeve member15is prevented. Further, in this case, an elastic seal member (not illustrated) such as rubber is accommodated in the slit51by adhesion, packing or the like. However, the elastic seal member may be omitted, depending on an application of the positioning apparatus.

Into a cylindrical hole of the plug member12is inserted a drive member21vertically movably. As illustrated inFIG. 2, the drive member21is provided with a piston22inserted hermetically into a lower part of the housing9, a piston rod23projected upward from the piston22, a bolt24screwed onto an upper part of the piston rod23, a cap member25fixed by the bolt24, and a ring26attached between the cap member25and an upper end surface of the piston rod23. Between the cap member25and the ring26is fitted an upper flange27of the sleeve member15horizontally movably.

A pin55is inserted into the piston22, and the pin55is engaged with an engaging hole formed on the housing9. As a result, rotation of the drive member21is blocked.

Inside the housing9are provided a lock means31and a release means32which construct the drive means D. The lock means31is constructed with a hydraulic chamber34provided for locking (hereinafter, referred to as a lock chamber) arranged above the piston22and with the piston22. Further, the release means32is constructed with a hydraulic chamber35provided for releasing (hereinafter, referred to as a release chamber) provided below the piston22and with the piston22.

The lock chamber34is communicatively connected with a lock port72formed at a lower surface of the flange9avia an oil passage71formed inside the housing9. Further, the release chamber35is communicatively connected with a bottom portion of the installation hole8.

On the lower surface of the flange9ais provided a blow port73. The blow port73is communicatively connected with inside of the cylindrical hole of the plug member12via an air passage74formed inside the housing9. Further, an outer peripheral surface of the piston rod23is notched to form a vertical passage75, and the vertical passage75is communicatively connected with the air passage74.

Then, when compressed air is supplied to the blow port73, the compressed air is led via the air passage74and the vertical passage75to a space between an upper end surface of the plug member12and the ring26, and discharged outside via the slit51, the gap A and the like. Thereby, various portions such as the inclined outer surfaces13,13and the inclined inner surface17are allowed to be cleaned.

Further, as illustrated inFIG. 1, on the lower surface of the flange9ais provided a positioning detection port85. The positioning detection port85is communicatively connected with a nozzle hole87opened in the support surface1aof the boss1bvia an air passage86formed inside the housing9.

When the supported surface2aof the work pallet2comes into contact with the support surface1aof the base plate1upon supply of compressed air to the positioning detection port85, the nozzle hole87is closed by the supported surface2a, thereby resulting in pressure rise of the positioning detection port85. By detecting the pressure rise with a pressure sensor (not illustrated), it possible to detect whether or not the supported surface2ais in contact with the support surface1a.

As illustrated inFIG. 2, an annular shallow recess is formed on an upper part of the outer peripheral surface of the sleeve member15, and an annular cover member53is fitted into the recess. The cover member53is formed in a circumferentially seamless manner, covering outside of an upper portion of the slit51. An upper end surface of the cover member53is in contact with a lower end surface of the cap member25. The cover member53acts to prevent intrusion of foreign matter such as metal swarf inside of the sleeve member15.

Between the upper flange27of the sleeve member15and the ring26is formed an annular gap. The annular gap allows the sleeve member15to deform and move in a diametrically expanding direction and a diametrically contracting direction.

Below the wedge member19is arranged a coned disc spring69as an advancing means. The coned disc spring69exerts resilient force in the direction which allows the wedge member19to advance upward (toward the leading end). In other words, the coned disc spring69exerts force in the direction so as to tighten a tapering engagement between the inclined outer surface13and the inclined inner surface17.

Additionally, the wedge member19is prevented from ascending to an amount exceeding the predetermined amount by being blocked by a flange70formed into an annular shape on an outer periphery of a leading end of the plug member12. Accordingly, an upper end (leading end) of the movable stroke of the wedge member19is regulated.

Further, on an outer periphery of a lower end portion of the plug member12is25formed an annular projection58. Then, when the wedge member19is lowered to compress the coned disc spring69in a predetermined amount, the coned disc spring69comes into contact with the projection58, thereby preventing additional compression. Accordingly, a lower end (base end) of the movable stroke of the wedge member19is regulated.

An explanation will be made for operation of the positioning apparatus by referring toFIG. 2andFIG. 3, andFIG. 4throughFIG. 8.

FIG. 4is an elevational cross sectional view illustrating a state in which the plug means6is inserted into the positioning hole5.FIG. 5is a cross sectional view indicated by the arrow5-5inFIG. 4.FIG. 6is an elevational cross sectional view illustrating a state in which the sleeve member15diametrically expands to come into close contact with the inner peripheral surface of the positioning hole5.FIG. 7is a cross sectional view indicated by the arrow7-7inFIG. 6.FIG. 8is an elevational cross sectional view illustrating a locked state.

In the released condition illustrated inFIG. 2andFIG. 3, pressurized oil has been discharged from the lock chamber34and pressurized oil has been supplied to the release chamber35. Thereby, the piston22has raised the piston rod23and the piston rod23has raised the sleeve member15via the bolt24and the ring26. In this case, between the upper end surface of the plug member12and the lower surface of the ring26is formed a contact gap.

Further, the wedge member19is raised by the operation of the coned disc spring69and kept stationary at a position contacting with the flange70(at a position corresponding to an advanced end of the movable stroke) or at a position close thereto. In this condition, the inclined outer surface13of the wedge member19is opposed to the inclined inner surface17of the sleeve member15in a minute space or slightly makes a tapering engagement therewith. Therefore, the sleeve member15is in a condition completely free of elastic deformation in a diametrically expanding direction (in a condition of a minimum deformation, if any). Additionally, the condition of the sleeve member15is called a “non diametrically-expanded condition.”

When the work pallet2is positioned with respect to the base plate1, at first, as illustrated inFIG. 4, in the above-described released condition, the work pallet2is lowered and the straight outer surface16of the sleeve member15is inserted into the positioning hole5. It is desirable that during the insertion, compressed air is supplied to the blow port73, thereby blowing foreign matter attached on various portions such as the inner peripheral surface of the positioning hole5and cleaning them. Since the sleeve member15is in the non diametrically-expanded condition, as described previously, an annular fitting gap G is formed between the straight outer surface16inserted into the positioning hole5and the inner peripheral surface of the positioning hole5.

Additionally, an explanation will be made hereinafter that, during the insertion, the axis of the positioning hole5is misaligned to the axis of the plug member12, and also misaligned to the first radial direction D1which is parallel to the slide surface63and a second radial direction (second diametrically direction) D2which is perpendicular thereto, as illustrated inFIG. 5. The fitting gap G is an eccentric gap as illustrated inFIG. 5, as a result of the above axial misalignment.

Subsequently, the pressurized oil is discharged from the release chamber35and also pressurized oil is supplied via the lock port72to the lock chamber34. Then, in the early stages of the pressurized oil supply, the piston22lowers the sleeve member15via the bolt24and the ring26by relatively low hydraulic pressure of the lock chamber34. The sleeve member15pushes the wedge member19but the descent is resisted by the resilient force of the coned disc spring69. As a result, the inclined inner surface17of the sleeve member15is wedge-engaged with the inclined outer surface13of the wedge member19. Thereby, as illustrated inFIG. 6andFIG. 7, the slide portions61,61allow the sleeve member15to expand elastically via the wedge member19toward the second radial direction D2, thereby bringing the sleeve member15into close contact with the inner peripheral surface of the positioning hole5. In the diametrically expanded and closely contacted condition of the sleeve member15, the fitting gap G illustrated inFIG. 4andFIG. 5is eliminated.

More specifically, the sleeve member15allows diametrically expanding force to act upon the inner peripheral surface of the positioning hole5only at portions opposing the slide portions61,61, instead of the entire circumferential direction. Therefore, regarding positional misalignment of the positioning hole5with respect to the plug member12(the positional misalignment illustrated inFIG. 5), the positional misalignment in the second radial direction D2is corrected by the close contact. On the other hand, the slide portions61,61is movable in the first radial direction D1along the slide surfaces63,63. Therefore, as illustrated inFIG. 7, the sleeve member15is allowed to move to some extent toward the first radial direction D1, together with the wedge member19and the slide portions61,61by the component force of the first radial direction D1of reaction force applied from the inner peripheral surface of the positioning hole5, when the positioning hole5is pressed. Therefore, regarding positional misalignment of the positioning hole5with respect to the plug member12, the positional misalignment in the first radial direction D1is allowed. In other words, the plug means6conducts an accurate positioning in the direction at which slide portions61,61oppose each other (the second radial direction D2) and allows positional misalignment in the direction orthogonal thereto (the first radial direction D1).

It follows that when pressure inside the lock chamber34is sufficiently increased, the sleeve member15in the closely contacted condition given inFIG. 6is strongly driven by the drive member21. Thereby, the sleeve member15compresses the coned disc spring69via the wedge member19and also descends, while rubbing and sliding on the positioning hole5.

Therefore, the drive member21strongly lowers the work pallet2via the sleeve member15, and the supported surface2aof the work pallet2is strongly pressed against the support surface1aof the base plate1.

It is noted that, where a contact gap exists between the support surface1aand the supported surface2a, the sleeve member15in the closely contacted condition rubs and slides as described above after the contact gap is eliminated.

Next, as illustrated in the locked condition ofFIG. 8, when the compressed coned disc spring69comes into contact with the projection58, the wedge member19is received via the coned disc spring69by the housing9, thereby preventing additional descent of the wedge member19(movement toward the base end). Therefore, descending force applied by the drive means D to the sleeve member15is substantially converted to diametrically expanding force of the sleeve member15by the inclined outer surface13and the inclined inner surface17. The sleeve member15strongly presses the inner peripheral surface of the positioning hole5in the second radial direction D2, resulting in a strong positioning in the second radial direction D2.

Further, during the locking movement, the sleeve member15is prevented from descending to an amount exceeding a predetermined amount by a lower surface of the ring26which comes into contact with the upper end surface of the plug member12.

When the locked condition as described above is changed to the released condition, the pressurized oil may be discharged from the lock chamber34and also pressurized oil may be supplied to the release chamber35. Thereby, the sleeve member15ascends by the bolt24and the ring26(release movement), and the sleeve member15returns to the non diametrically-expanded condition by its own elastic restoring force, while releasing the tapering engagement with the wedge member19, thereby the locked condition is released. Thereafter, the work pallet2is raised.

As explained above, in the present embodiment, positioning can be conducted by eliminating the fitting gap G (refer toFIG. 4andFIG. 5) in the condition that the sleeve member15is inserted into the positioning hole5. Therefore, it is possible to smoothly and easily insert the sleeve member15into the positioning hole5and at the same time positioning with high accuracy can be conducted.

Further, in a direction at which the slide portions61,61oppose each other (the second radial direction D2), positioning with high accuracy can be conducted. In a direction parallel to the slide surface63(the first radial direction D1), positional misalignment of the positioning hole5to the plug member12can be allowed.

In addition, in the present embodiment, positional misalignment of the positioning hole5to the plug member12in the first radial direction D1is smoothly absorbed by the slide portions61,61which slide along the slide surface63. A specific explanation will be made for effects thereof by comparison with a structural example given inFIG. 9.

Namely, a construction as given inFIG. 9may be available as a construction wherein positioning with high accuracy is conducted in the second radial direction D2and also positional misalignment is allowed in the first radial direction D1.FIG. 9is a view illustrating a construction that the inventor proposed previously, corresponding toFIG. 3. In this case, instead of the slide portions61,61, projections91,91projecting in the second radial direction D2are formed on an outer peripheral surface of the plug member12so as to oppose each other in a radial direction. On these projections91,91are formed straight outer surfaces92,92, and the inner peripheral surface of the wedge member19is in contact with the straight outer surfaces92,92. On the plug member12is formed an escape groove at a position between these projections91,91, as a result, between the wedge member19and the plug member12are formed gaps A, A in the first radial direction D1.

In the construction given inFIG. 9as well, due to the locking movement of the sleeve member15, positioning with high accuracy in the second radial direction D2can be conducted, and also positional misalignment can be allowed in the first radial direction D1orthogonal thereto since the sleeve member15and the wedge member19are allowed to be moved, as illustrated by the chain line.

However, in the construction given inFIG. 9, when the sleeve member15and the wedge member19move in the first radial direction D1, as illustrated by the chain line, with respect to the projections91,91, the straight outer surface92of the projection91comes into partial contact with the inner peripheral surface of the wedge member19. Because a large friction occurs at the partially contacted portion, the sleeve member15and the wedge member19do not move smoothly in the first radial direction D1with respect to the projections91,91. Further, when the sleeve member15moves in the first radial direction D1, lopsided force may be often locally applied to corners of the straight outer surface92of the projection91or to the inner peripheral surface of the wedge member19. In particular, when external force in the second radial direction D2is applied to the work pallet2in a positioned condition, excessive force is applied to the partially contacted portion, and damage such as an impression may be generated on the inner peripheral surface of the wedge member19or the straight outer surface92. In order to prevent the harmful results, it is necessary to use high-quality materials such as special alloy steels or to provide proper hardening process for the materials, resulting in an increased production cost.

Further, in order to reduce harmful results resulting from the partial contact above, there is a case that the projections91,91are made small to decrease a contact area between the straight outer surface92of the leading end surface and the inner peripheral surface of the wedge member19. However, in this case, since force is transmitted only at a small area, the sleeve member15is unable to increase diametrically expanding force in the second radial direction D2. In addition, lowering force of the work pallet2cannot be secured sufficiently and reliably via the sleeve member15.

In the construction of the present embodiment (refer toFIG. 7), however, where the sleeve member15is moved toward the first radial direction D1in order to absorb positional misalignment in the first radial direction D1, the slide portions61,61are also25moved accordingly. Therefore, the straight outer surfaces of the slide portions61,61do not come into partial contact with the inner peripheral surface of the wedge member19. Then, the straight outer surfaces of slide portions61,61or the inner peripheral surface of the wedge member19is not damaged.

Further, in the construction of the present embodiment, even where a contact area is enlarged between the straight outer surface of the slide portion61and the inner peripheral surface of the wedge member19, the sleeve member15and the wedge member19are moved smoothly along the slide surface63, together with the slide portions61,61. Therefore, during the locking operation, the sleeve member15and the wedge member19follow positional misalignment in the first radial direction D1and lo move smoothly while sliding, thereby making it possible to smoothly absorb the positional misalignment in the first radial direction D1. This fact means that a contact area is made larger between the straight outer surface of the slide portions61and the inner peripheral surface of the wedge member19, and diametrically expanding force is made larger which is applied by the sleeve member15to the inner peripheral surface of the positioning hole5. It also means that in a condition that the sleeve member15is in close contact with the inner peripheral surface of the positioning hole5, lowering force of the work pallet2can be made larger.

In addition, in the present embodiment, the sleeve member15presses the inner peripheral surface of the positioning hole5more strongly in a condition given inFIG. 8where the wedge member19is prevented from moving toward the lower end than in a condition given inFIG. 6. Therefore, an accurate positioning in the second radial direction D2is accomplished.

Furthermore, in the present embodiment, the inclined outer surface13is formed on the wedge member19and the inclined inner surface17is formed on the sleeve member15. Therefore, the second block2is allowed to be positioned in the second radial direction D2with respect to the first block1more reliably and strongly by mechanical expanding force derived from the tapering engagement. When the drive member21is driven by the drive means D to move the sleeve member15for locking, the second block2is allowed to be pressed against the first block1via the sleeve member15, thereby making it possible to omit an exclusive clamping means.

Moreover, in the present embodiment is provided the coned disc spring69which allows the wedge member19to advance to the leading end. Therefore, when the sleeve member15is moved to the base end for locking, the sleeve member15attempts to move the wedge member19to the base end, to which the resilient force of the coned disc spring69resists. Therefore, the sleeve member15is smoothly expanded diametrically by the tapering engagement.

Furthermore, in the present embodiment, the sleeve member15is formed into an annular shape. Therefore, intrusion of foreign matter such as swarf inside of the sleeve member15is made difficult.

In the present embodiment, the slit51is formed in the sleeve member15. The sleeve member15is constructed so as to be deformable in a diametrically expanding and diametrically contracting direction by existence of the slit51. Therefore, such a simple construction is realized that the sleeve member15is allowed to be deformed in the diametrically expanding and diametrically contracting direction. Further, as compared with a case where the sleeve member15is formed in a seamless manner, the sleeve member15is allowed to be deformed to a larger amount. Accordingly, since the fitting gap G (illustrated inFIG. 4andFIG. 5) is made larger in the non diametrically-expanded condition, the straight outer surface16is effectively inserted into the positioning hole5.

Further, in the present invention, the wedge member19is formed into an annular shape. Therefore, intrusion of foreign matter such as swarf inside of the wedge member19is made difficult.

In the present embodiment, the slit57is formed in the wedge member19.

Then, the wedge member19is constructed so as to be deformable in a diametrically expanding and diametrically contracting direction by the slit51. Therefore, such a simple construction is accomplished that the wedge member15is allowed to be deformed in the diametrically expanding and diametrically contracting direction.

Further, between the wedge member19and the plug member12are formed gaps A, A in the first radial direction D1. Therefore, during the locking movement, the sleeve member15and the wedge member19follow positional misalignment in the first radial direction D1to move smoothly while sliding, thereby making it possible to smoothly absorb the positional misalignment in the first radial direction D1.

An explanation has been made for the first embodiment, which may be changed as illustrated in the following (1) through (7).

(1) The inclined outer surface13may be provided on an outer surface of another member arranged outside the wedge member19, instead of being provided on the outer surface of the wedge member19. Further, the slide outer surface64may be provided on an outer surface of another member arranged outside the plug member12, instead of being provided on the outer surface of the plug member12.

(2) Where a greater deformation is not necessary which allows the sleeve member15to expand diametrically for coming into close contact with the inner peripheral surface of the positioning hole5, the slit51is not formed in the sleeve member15but the sleeve member15may be formed into an annularly seamless. Further, the slit57is not formed in the wedge member19but the wedge member19may be formed in an annularly seamless manner.

(3) Further, the wedge member19may be constructed as a plurality of divided members divided circumferentially. A pair of the slide portions61,61may be connected via a thin member (not illustrated) extending along the respective gaps A, A, or may be formed integrally with the thin member.

(4) The drive member21is driven vertically by hydraulic pressure. However, it may be driven by supplying compressed air to the lock chamber34or the release chamber35for example. Further, the drive member21is not necessarily driven by a pressurized fluid but may be driven upward or downward by using a spring for example. The spring may include a compression coil spring and a single or a laminated coned disc spring.

(5) The plug means6may be inserted into the positioning hole5by raising the base plate1, instead of lowering the work pallet2. Further, a construction may be provided that the work pallet2is lowered and the base plate1is raised at the same time.

(6) In the work pallet2is formed the positioning hole5in a penetrating manner, however, the positioning hole5may be formed into such a shape so as to be opened only in the lower surface of the work pallet2.

(7) The present embodiment may be constructed in such a way that the plug member12and the positioning hole5are arranged so that their axes are kept lateral and the plug means6is inserted into the positioning hole5horizontally. As a matter of course, the plug means6may be inserted thereinto in an oblique direction.

Then, with reference toFIG. 10throughFIG. 19, an explanation will be made for a plurality of embodiments and exemplary variations of the positioning apparatus in the present invention. In these other embodiments, the members which are the same or similar to those used in the first embodiment are in principle given the same reference numeral.

Second Embodiment

FIG. 10is a view illustrating a second embodiment of the positioning apparatus, corresponding toFIG. 2.

In the positioning apparatus of the second embodiment, as illustratedFIG. 10, the coned disc spring is omitted, but instead, an annular advance piston (advancing means)69is hermetically engaged with the housing9and the piston rod23. The advance piston69is movable vertically (axially).

The advance piston69is driven upward by pressurized oil of the lock chamber34. However, the pressure receiving area of the advance piston69is smaller than that of the piston22of the lock chamber34.

A plurality of transmission pins76are supported on the housing9so as to be movable vertically (axially). A lower end of the transmission pin76is in contact with the advance piston69, and an upper end thereof is in contact with the wedge member19.

The positioning apparatus of the second embodiment is different in operation from that of the first embodiment in the following points.

Since in the released condition given inFIG. 10, pressurized oil has been supplied to the release chamber35, the piston22has been raised. As a result, the drive member21has raised the sleeve member15. Further, the piston22has pushed up the advance piston69, by which the wedge member19has been raised via the transmission pin76. In this condition, the sleeve member15is in the previously described non diametrically-expanded condition.

When the pressurized oil is discharged from the release chamber35and pressurized oil is supplied to the lock chamber34in the released condition, the piston22is pushed down and the sleeve member15is lowered. The sleeve member15attempts to lower the wedge member19, to which hydraulic pressure acting on the advance piston69upward resists. As a result, the sleeve member15makes a tapering engagement with the wedge member19, while pushing down the wedge member19, diametrically expanding in the second radial direction to come into close contact with the inner peripheral surface of the positioning hole5of the work pallet2.

Further, when the piston22is lowered and the wedge member19is lowered by a predetermined movable stroke, the transmission pin76is in a condition where it is not projected from an upper surface of the flange9a, and the wedge member19is directly received by the flange9a. Therefore, additional descent of the wedge member19(movement to the base end) is prevented, and the sleeve member15strongly presses the inner peripheral surface of the positioning hole5of the work pallet2in the second radial direction D2.

Instead of being driven by pressurized oil, the advance piston69may be driven by other pressurized fluid, for example, compressed air.

Additionally, such a construction that the advance piston69driven by the above pressurized fluid is used as an advancing means is applicable to any of a third embodiment through a seventh embodiment.

Third Embodiment

FIG. 11is a view illustrating a third embodiment of the positioning apparatus, corresponding toFIG. 4.

The third embodiment is different from the first embodiment in the following points.

As illustrated inFIG. 11, instead of forming a boss on the flange9a, an upper surface of the flange9ais projected upward annularly around the base end of the plug member12, and an upper surface of the annular projection1bis given as the support surface1a. In the support surface1ais opened the nozzle hole87.

The inclined outer surface13of the wedge member19(second pressing member) is formed in an inclined manner so as to get closer to the axis of the plug member12downward (toward the base end). Corresponding thereto, the inclined inner surface17of the sleeve member15(first pressing member) is formed in an inclined manner so as to get closer to the axis of the plug member12downward (toward the base end).

Between the cap member25and the ring26is inserted an upper flange27of the wedge member19. Below the sleeve member15is arranged a coned disc spring69, with two sheets superimposed. The coned disc spring69urges the sleeve member15in an advancing direction. In other words, the coned disc spring69exerts force in such a direction as to tighten the tapering engagement of the inclined outer surface13with the inclined inner surface17. Additionally, a flange portion77formed at a lower part of the sleeve member15is allowed to come into contact with a flange70formed at an upper end and in a periphery of the annular projection1b, thereby preventing advancement of the sleeve, member15to an amount exceeding a predetermined amount.

The positioning apparatus of the third embodiment is different in operation from that of the first embodiment in the following points.

In the released condition given inFIG. 11, the wedge member19has been kept raised by the piston22. Further, the sleeve member15has been raised by the action of the coned disc spring69and has been kept stationary at a position contacting with the flange70(at a position corresponding to an advanced end of the movable stroke) or at a position close thereto.

When the wedge member19is lowered by the drive member21during the locking drive, the wedge member19attempts to lower the sleeve member15, to which the resilient force of the coned disc spring69resists. As a result, the inclined outer surface13of the wedge member19is wedge-engaged with the inclined inner surface17of the sleeve member15. Thereby, the slide portions61,61elastically expand the sleeve member15via the wedge member19in the second radial direction, allowing the sleeve member15to come into close contact with the inner peripheral surface of the positioning hole5.

As with the first embodiment, the sleeve member15is received via the coned disc spring69by the housing9, by which additional descent of the sleeve member15(movement to the base end) is prevented. As a result, downward force applied by the drive means D to the wedge member19is substantially converted to diametrically expanding force of the sleeve member15via the inclined outer surface13and the inclined inner surface17. The sleeve member15strongly presses the inner peripheral surface of the positioning hole5in the second radial direction.

Fourth Embodiment

FIG. 12andFIG. 13are views illustrating a fourth embodiment of the present invention.

FIG. 12is a view corresponding toFIG. 4.FIG. 13is a cross sectional view indicated by the arrow13-13inFIG. 12, corresponding toFIG. 5.

The fourth embodiment is different from the first embodiment in the following points.

The plug means6is not provided with the wedge member but, instead, formed with inclined outer surfaces13,13on the slide portions61,61. The inclined outer surfaces13,13are formed into a tapered shape so as to get closer to the axis upward (toward the leading end). The inclined outer surface13of the slide portions61is allowed to be directly in contact with the inclined inner surface17of the sleeve member15(pressing member).

Outside a lower end portion of the plug member12is arranged an annular collar54which is formed in a circumferentially seamless manner. The annular collar54is fitted into an inner periphery at the lower part of the sleeve member15between the coned disc spring69to be described later and the slide portion61. The annular collar54is able to prevent intrusion of foreign matter such as swarf derived from metal working inside of the sleeve member15.

Each of the slide portions61,61is arranged on the plug member12along the slide surface63in a movable condition in the first radial direction D1.

Further, the slide portions61are axially movable by a predetermined stroke with respect to the plug member12. More specifically, in order to form the slide outer surfaces64,64, a vertical dimension of a groove formed in the plug member12is made slightly larger than that of the slide portion61, by which the slide portion61is allowed to move vertically inside the groove by the movable stroke to be explained later.

Between the annular collar54and the flange9ais arranged a coned disc spring69as an advancing means. The coned disc spring69exerts resilient force in such a direction as to make the slide portions61,61advance upward (toward the leading end) via the annular collar54. In other words, the coned disc spring69exerts force in such a direction as to tighten the tapering engagement of the inclined outer surface13with the inclined inner surface17.

Further, ascent of the slide portions61,61larger than a predetermined range is prevented by a flange70formed on an outer periphery of the leading end of the plug member12. Thereby, the limit of the movable stroke of the slide portions61,61at the upper end (leading end) is regulated. A restricting surface78for preventing movement of the slide portion61to the lower end is formed on a base end portion of the groove. Thereby, the limit of the movable stroke of the slide portions61,61at the lower end (base end) is regulated.

The positioning apparatus of the fourth embodiment is different in operation from that of the first embodiment in the following points.

In the released condition given inFIG. 12andFIG. 13, the sleeve member15has been kept raised by the piston22. The slide portions61,61has been raised by the action of the coned disc spring69and has been kept stationary at a position contacting with the flange70(at a position corresponding to an advanced end of the movable stroke) or at a position close thereto.

When the sleeve member15is lowered by the drive member21during the locking drive, the sleeve member15attempts to lower the slide portions61,61, to which resilient force of the coned disc spring69resists. As a result, the inclined inner surface17of the sleeve member15is wedge-engaged with the inclined outer surface13of the slide portions61,61. Thereby, the sleeve member15elastically expands diametrically in the second radial direction D2, coming into close contact with the inner peripheral surface of the positioning hole5. Then, regarding positional misalignment of the positioning hole5with respect to the plug member12, the positional misalignment in the second radial direction D2is corrected.

Further, the slide portions61,61is movable along the slide surfaces63,63in the first radial direction D1, thereby the sleeve member15is allowed to move to some extent toward the first radial direction D1, together with the slide portions61,61by the component force of the first radial direction D1of reaction force applied from the inner peripheral surface of the positioning hole5, when the sleeve member15comes into close contact with the inner peripheral surface of the positioning hole5. Therefore, regarding positional misalignment of the positioning hole5with respect to the plug member12, the positional misalignment in the first radial direction D1is allowed.

Thereafter, when the slide portions61,61are lowered to a predetermined amount and kept in contact with the restricting surface78, the slide portions61,61are received by the plug member12(the housing9), thereby preventing additional descent of the slide portions61,61(movement to the base end). As a result, descending force applied by the drive means D to the sleeve member15is substantially converted to diametrically expanding force of the sleeve member15by the inclined outer surface13and the inclined inner surface17. The sleeve member15strongly presses the inner peripheral surface of the positioning hole5in the second radial direction D2.

In the present embodiment, a wedge member necessary in the first embodiment through the third embodiment can be omitted to provide a simple construction.

A pair of the slide portions61,61and the annular collar54may be formed integrally, instead of being formed separately.

Further, a pair of the slide portions61,61may be connected via a thin member (not illustrated) extending along the gaps A, A or formed integrally with the thin member.

The above exemplary variations are applicable to individual embodiments to be described later.

Fifth Embodiment

FIG. 14is a view illustrating a fifth embodiment of the present invention, corresponding toFIG. 4.

The fifth embodiment is given as an exemplary variation of the fourth embodiment. As illustrated inFIG. 14, no boss is projected on the base plate1, instead, an upper surface of the flange9aon the housing9is annularly projected to construct the support surface1aon an upper end surface of the annular projection1b.

Into a screw hole66opened in the upper end surface of the plug member12is screwed a lower part of a flanged bolt67. In a head of the flanged bolt67is opened a hexagonal hole (not illustrated), and a hexagon wrench68is allowed to be engaged with the hole as illustrated by the chain line. Between the head of the flanged bolt67and the flange portion is supported the cap member25relatively rotatably and vertically unmovably. Into a engaging recess56formed at the lower part of the cap member25is fitted an upper flange27of the sleeve member15.

In the present embodiment, the flanged bolt67corresponds to the drive member21. Further, the drive means D is constructed with the screw hole66and the hexagon wrench68.

In the above described construction, when the hexagon wrench68is inserted into the head of the flanged bolt67to turn the head, the flanged bolt67is screwed into a vertical direction. Thereby, the sleeve member15is moved downward for locking or moved upward for releasing. As a result, the sleeve member15diametrically expands or contracts by a tapering engagement with the inclined outer surfaces13,13, which are outer surfaces of the slide portions61,61. Other constructions and operations are similar to those described in the fourth embodiment.

Such a construction that a screw member such as a bolt67is used as a drive member as described in the present embodiment is applicable to other embodiments as well illustrated in the present specification.

Sixth Embodiment

FIG. 15throughFIG. 18are views illustrating a sixth embodiment of the present invention.

FIG. 15is a view corresponding toFIG. 4.FIG. 16is a cross sectional view indicated by the arrow16-16inFIG. 15.FIG. 17is a cross sectional view illustrating a state that the engaging member15undergoes displacement in a diametrically expending direction to come into close contact with the inner peripheral surface of the positioning hole5.FIG. 18is an enlarged view illustrating major parts ofFIG. 17.

The sixth embodiment is given as an exemplary variation of the fourth embodiment (FIG. 12andFIG. 13).

With a groove formed between the cap member25and the ring26is engaged an upper flange27of a cylindrical connecting member81. On a cylindrical wall of the connecting member81is formed a support window82which opposes the inclined outer surface13of the slide portion61. Into the support windows82,82are fitted a pair of the engaging members15,15(pressing members) which is constructed into a block shape radially movably.

These engaging members15,15are arranged to oppose each other in a radial direction so as to hold both the slide portions61,61therebetween. Further, on each of the engaging members15,15is formed an inclined inner surface17, and the inclined inner surface17is allowed to make a tapering engagement with the inclined outer surface13of the slide portion61. Both the inclined outer surface13and the inclined inner surface17are formed into tapered surfaces so as to get closer to the axis toward the leading end.

On each engaging member15is formed a straight outer surface16. In this embodiment, fine serrate irregularities are formed on the straight outer surface16, as illustrated inFIG. 15. When the engaging member15is brought into close contact with the inner peripheral surface of the positioning hole5on the work pallet2, the irregularities provide a large friction to strongly lower the work pallet2via the engaging members15,15. However, as with other embodiments, the straight outer surfaces16,16may be formed into a flat surface.

A through hole83is circumferentially formed in each of the engaging members15,15. A ring spring84(returning member) arranged on an outer periphery of the plug member12is inserted into the through hole83. The ring spring84applies resilient force to the engaging members15,15in a diametrically contracting direction.

Into a lower end portion of the plug member12is fitted an annular spring support88. Between the spring support88and the slide portions61,61is attached a compression coil spring69(advancing means). The compression coil spring69urges the slide portions61,61upward (toward the leading end).

Outside the spring support88is arranged an annular collar54which is formed in a circumferentially seamless manner. The annular collar54is fitted into an inner periphery of a lower portion of the connecting member81. The annular collar54is able to prevent intrusion of foreign matter such as swarf derived from metal working inside of the connecting member81.

Between the upper flange27of the connecting member81and the ring26is formed an annular gap. Also between the annular collar54and the spring support88is formed an annular gap. These annular gaps allow the connecting member81to move in a radial direction.

In the released condition illustrated inFIG. 15andFIG. 16, the connecting member81has been raised by the drive member21, and the engaging members15,15have also been raised. Further, the slide portions61,61have also been raised by the action of the compression coil spring69. In the released condition, the engaging members15,15are pulled in a diametrically contracting direction by the ring spring84and kept in a condition that they are hardly projected from an outer surface of the connecting member81(non diametrically-expanded condition).

When the pressurized oil is discharged from the release chamber35and pressurized oil is supplied to the lock chamber34in the released condition, the drive member21is driven downward. Along with descent of the drive member21, the connecting member81is moved downward, thereby lowering the engaging members15,15connected to the connecting member81(lock movement).

As a result, the engaging members15,15make a tapering engagement with the slide portions61,61kept at an raised position by the resilient force of the compression coil spring69, thereby undergoing displacement in a diametrically expanding direction (in the second radial direction D2), while allowing the ring spring84to undergo an elastic deformation, thereby projecting from the connecting member81. Then, as illustrated inFIG. 17, the straight outer surfaces16,16of the engaging members15,15come into close contact with the inner peripheral surface of the positioning hole5. It follows that the closely contacted engaging members15,15strongly lower the work pallet2.

In the sixth embodiment, a construction is provided that the engaging members15,15formed into a block shape diametrically expand to undergo displacement in the second radial direction D2, allowing the straight outer surface16to come into close contact with the inner peripheral surface of the positioning hole5, thereby allowing diametrically expanding force to act upon. Therefore, regarding positional misalignment of the positioning hole5with respect to the plug member12(positional misalignment illustrated inFIG. 16), the positional misalignment in the second radial direction D2is corrected by the close contact. On the other hand, the slide portions61,61are movable in the first radial direction D1, along the slide surface63and the slide outer surface64. Thus, as illustrated inFIG. 17, the engaging members15,15are allowed to move to some extent toward the first radial direction D1, together with the connecting member81and the slide portions61,61by the component force of the first radial direction D1of reaction force applied from the inner peripheral surface of the positioning hole5, when the positioning hole5is pressed. Therefore, regarding positional misalignment of the positioning hole5with respect to the plug member12, the positional misalignment in the first radial direction D1is allowed.

In the present embodiment, a construction is provided that the engaging members15,15which undergo displacement in a diametrically expanding direction come into close contact with the inner peripheral surface of the positioning hole5. Therefore, the engaging members15,15are allowed to be displaced in a larger amount, as compared with the previously described first embodiments through the fifth embodiments where the annular sleeve member is deformed and brought into close contact with the inner peripheral surface of the positioning hole5. As a result, the fitting gap (gap G illustrated inFIG. 16) in the non diametrically-expanded condition is made larger and the engaging member15can be inserted into the positioning hole5more smoothly.

FIG. 18is an enlarged view illustrating one of the two pairs composed of the engaging members15and the slide portions61given inFIG. 17. As illustrated inFIG. 18, on outer surfaces of each of the engaging members15,15are formed two contact portions15a,15aand an escape portion15barranged between these two contact portions circumferentially side by side. The contact portions15a,15a(corresponding to the straight outer surfaces16,16) are formed into an arc surface and adapted to be in contact with the inner peripheral surface of the positioning hole5. Further, the escape portion15bis formed into a flat surface. Then, when the contact portions15a,15acome into contact with the inner peripheral surface of the positioning hole5, a gap B is formed between the escape portion15band the inner peripheral surface of the positioning hole5.

As constructed as described above, positioning can be appropriately conducted even in a case where the positioning hole5has a larger inner diameter and the engaging members15,15are required to undergo a larger displacement so as to come into close contact with the inner peripheral surface of the positioning hole5. Namely, the construction is that the inner peripheral surface of the positioning hole5is pushed at two contact portions15a,15aeach for the engaging members15,15totaling four contact portions, however, not pushed at the escape portion15b. Therefore, the engaging member15applies diametrically expanding force (force in the second radial direction D2) at the four points of the contact portions15a, thereby making it possible to correct appropriately and reliably the positional misalignment in the second radial direction D2occurring between the positioning hole5and the plug member12.

Further, on outer surfaces of each of the slide portions61are formed two contact portions61a,61aand an escape portion61barranged between these two contact portions circumferentially side by side. The contact portions61a,61aare formed into a conical surface so as to come into contact with the inner surface of the engaging member15. In addition, the escape portion61bis formed into a flat surface, and between the escape portion61band the inner surface of the engaging member15is formed a gap C. Therefore, a construction is possible that two contact portions61a,61afor each of the slide portions61,61totaling four contact portions are in contact with the inner surface of the engaging member15and during the lock movement as described above, the engaging member15is allowed to receive the reaction force applied from the inner peripheral surface of the positioning hole5at these four points stably. Thus, the positional misalignment of the positioning hole5with respect to the plug member12in the second radial direction D2is allowed to be appropriately and reliably corrected.

Further, the escape portion61b is not limited to being formed on the outer surface of the slide portion61. For example, the escape portion may be formed by forming the outer surface of the slide portion61into a conical surface across the entire circumferential direction and recessing a central part of the inner surface of the engaging member15circumferentially into a V shape.

In addition, in the present embodiment, the cylindrical connecting member81is arranged around the outer periphery of the plug member12and the engaging member15is supported on the support window82of the connecting member81movably in the second radial direction D2. Therefore, such a simple construction is provided that supports the engaging members15,15formed into a block shape. In the present embodiment, since the connecting member81is connected to the drive member21, the connecting member81is allowed to be driven by the drive means D. As a result, the engaging members15,15are allowed to be moved for locking and releasing easily by moving the connecting member81upwardly and downwardly. In addition, the connecting member81is formed into a cylindrical shape, thereby a construction can be provided that intrusion of foreign matter inside the connecting member81is made difficult.

In addition, the present embodiment is provided with a ring spring84which acts resilient force in a diametrically contracting direction upon the engaging members15,15. Therefore, during the releasing movement, the engaging members15,15formed into a block shape can easily return to the non diametrically-expanded condition. It is noted that the ring spring84is not limited to a metal spring but may be replaced by an elastic material such as rubber.

The return means for the engaging member15is provided by connecting the engaging member15with the slide portion61with a T-shaped fitting structure, when viewed from above.

Further, such a structure that the engaging member15is supported on the connecting member81is applicable to the first embodiment and others. More specifically, instead of the sleeve member15in the first embodiment (FIG. 2), the connecting member81and the engaging members15,15in the present embodiment may be arranged outside the wedge member19(FIG. 2).

In embodiments other than the present embodiments which are disclosed in the present specification, it is possible to form serrate irregularities on the outer surface of the straight outer surface16. Further, the irregularities on the straight outer surface16are not limited to a serrate shape but may be available in various shapes.

Seventh Embodiment

FIG. 19is a transverse cross sectional view illustrating the positioning apparatus of a seventh embodiment and similar toFIG. 16.

The seventh embodiment is given as an exemplary variation of the sixth embodiment. As illustrated inFIG. 19, two pairs of the engaging members15are provided so as to oppose each other in a radial direction across the slide portions61,61. In the connecting member81are opened four support windows82for supporting four engaging members15.

As illustrated inFIG. 19, a direction at which each pair of the engaging members15,15oppose each other (direction at which the engaging members15,15are projected during the locking movement, namely, equivalent to the second radial direction D2) is not perpendicular to the first radial direction D1but inclined. Further, a direction D2at which one pair of the engaging members15,15oppose each other and a direction D2at which the other pair of the engaging members15,15oppose each other are symmetrical with respect to a line perpendicular to the first radial direction D1.

A pair of inclined outer surfaces13,13are provided at each of the slide portions61,61circumferentially and bilaterally. The inclined outer surfaces13,13are not formed into a conical surface but formed into an inclined flat surface so as to get closer to the axis toward the leading end. Outside each of the inclined outer surfaces13,13is arranged the engaging member15. The inner surface (the inclined inner surface17) of the engaging member15is not formed into a conical surface but formed into an inclined flat surface so as to get closer to the axis toward the leading end. When viewed from above as illustrated inFIG. 19, the inclined outer surface13and the inclined inner surface17are perpendicular to the second radial direction D2and slightly inclined to the first radial direction D1.

In the seventh embodiment, the connecting member81is lowered via the drive member21, by which each of the engaging members15,15moves downward for locking, and the engaging member15diametrically expands in the second radial direction D2by the tapering engagement of the inclined outer surface13with the inclined inner surface17, and the engaging member15comes into close contact with the inner peripheral surface of the positioning hole5. As a result, the positional misalignment in the second radial direction D2, D2is corrected.

As described previously, the direction D2at which one pair of the engaging members15,15oppose each other and the direction D2at which the other pair of the engaging members15,15oppose each other are symmetrical with respect to the line perpendicular to the first radial direction D1. Therefore, positional misalignment perpendicular to the first radial direction D1is corrected by the locking movement. Further, positional misalignment in the first radial direction D1is also allowed, as with the sixth embodiment.

In the seventh embodiment, the outer surface of each of the engaging members15,15is formed into a simple arc surface (straight outer surface16) and the escape portion which is provided in the sixth embodiment is not provided. The reason thereof is that, in the present embodiment, four engaging members15are simultaneously projected in the second radial direction D2, thereby applying diametrically expanding force to the inner peripheral surface of the positioning hole5of the work pallet2at four points in the direction perpendicular to the first radial direction D1, making it possible to correct positional misalignment perpendicular to the first radial direction D1. Other constructions and operations are similar to those described in the sixth embodiment.

It is noted that the engaging member15may be provided in three pairs or more, instead of two pairs.

Modified Embodiment

The positioning apparatus described in the first embodiment through the seventh embodiment may be changed as follows.

(1) The plug member12and the housing9may be formed separately, instead of being formed integrally. In this case, the plug member12may be firmly fixed to the housing9by using bolts, screws and the like.

(2) Further, the housing9and the base plate1may be formed integrally, instead of being formed separately.

(3) The slide surfaces63,63and the slide outer surfaces (inclined outer surfaces)64,64may be formed in an inclined manner with respect to the first radial direction D1, instead of being formed in a parallel manner with respect to the first radial direction D1.

(4) The slide portions61,61may be provided in two or more pairs of them, in addition to being provided in one pair of them.

(5) The support surface1amay be formed directly on a flat upper surface of the housing9, instead of being formed at the boss1bof the housing9. Further, the support surface1amay also be formed on a boss projected from the base plate1upward.

Hereinafter, an explanation will be made for a first example applied to the clamping system of the positioning apparatus by referring toFIG. 20.

FIG. 20is a schematic plan view of a clamping system.

As illustrated inFIG. 20, on an upper surface of a table T of a machining center is fixed the base plate1. The work pallet2is allowed to be attached to or detached from the base plate1via the clamping system of the present invention. The clamping system is provided with a first positioning apparatus101and a second positioning apparatus102.

The work pallet2is available in a plural number (only one piece is illustrated inFIG. 20) and may be exchanged and attached to the base plate1, whenever necessary. When the work pallet2is attached to the base plate1, the work pallet2is positioned and fixed by the two positioning apparatuses101,102.

The first positioning apparatus101is provided with a sleeve member15which is inserted into the inner peripheral surface of the positioning hole5opened in the work pallet2, and the sleeve member15is allowed to come into close contact with the inner peripheral surface of the positioning hole5by acting diametrically expanding force over substantially the whole periphery of the sleeve member15and the work pallet2is positioned horizontally with respect to the base plate1via the sleeve member15. More specifically, the sleeve member15is positioned so as to make an axis of the positioning hole5coincide with an axis A of the first positioning apparatus101. It follows that the closely contacted sleeve member15is driven downward to fix the work pallet2to the base plate1.

It is noted that the first positioning apparatus101may be available in various specific constructions. It is structurally available that, in the positioning apparatus of the first embodiment, both the slide outer surfaces64,64and the slide portions61,61are not provided but the wedge member19is arranged so as to come into close contact with over an entire outer peripheral surface of the plug member12(so as to be free of the gaps A, A) and the inclined inner surface17of the sleeve member15is allowed to make a tapering engagement with the inclined outer surface13of the wedge member19.

Further, the positioning apparatus (refer toFIG. 1andFIG. 2) of the first embodiment is employed as the second positioning apparatus102. The slide portions61,61are arranged so as to oppose each other in a direction substantially orthogonal to a line L connecting an axis A of the positioning apparatus101with an axis B of the positioning apparatus102. In other words, the slide portions61,61are arranged so that the second radial direction D2is substantially orthogonal to the line L. Therefore, diametrically expanding force acts on the sleeve member15in the direction at which the slide portions61,61oppose each other (the second radial direction D2), by which rotation of the work pallet2around the axis A is prevented. In this case, the sleeve member15moves together with the wedge member19and the slide portions61,61along the slide surfaces63,63(the first radial direction D1), thereby radial misalignment with respect to the axis A is absorbed. It follows that the closely contacted sleeve member15is driven downward to fix the work pallet2to the base plate1.

Since the positioning apparatus of the first embodiment is employed as the second positioning apparatus102in the present clamping system, positioning with high accuracy can be conducted. Further, when the work pallet2and the base plate1are attached or detached, a condition in which the fitting gap G (illustrated inFIG. 4andFIG. 5) is formed between the inner peripheral surface of the positioning hole5and the straight outer surface16in the second positioning apparatus102can be obtained. Thereby, workability is improved upon attachment and detachment. Further, during the locking movement, in the second positioning apparatus102, the work pallet2can approach the base plate1via the sleeve member15, thereby making it possible to omit an exclusive clamping means, whenever necessary.

In addition, by employing the positioning apparatus of the first embodiment as at least one of these positioning apparatuses101,102, a clamping system capable of positioning in various modes can be provided, as explained in the present clamping system.

FIG. 21is a schematic plan view illustrating a second example applied to the clamping system of the above-described positioning apparatus. The second example is constructed as a preferable example for fixing a long work pallet2to the base plate1. As illustrated inFIG. 21, in the second example, three positioning apparatuses111through113of the first embodiment are provided side by side in a longitudinal direction of the work pallet2.

In the middle positioning apparatus112, a direction to which the slide portions61,61are opposed is along the longitudinal direction of the work pallet2. In the positioning apparatus112, the work pallet2is positioned with respect to the longitudinal direction.

Further, in the positioning apparatuses111,113arranged at both ends, a direction to which the slide portions61,61are opposed is substantially perpendicular to the longitudinal direction of the work pallet2. These positioning apparatuses111,113are employed for positioning with respect to the direction perpendicular to the longitudinal direction of the work pallet2, also for blocking rotation of the work pallet2around the axis of the middle positioning apparatus112.

[Modified Examples of the Clamping System]

The above-described clamping system can be changed as follows.

(1) The first example given inFIG. 20is not limited to a construction in which the positioning apparatus of the first embodiment is employed as the second positioning apparatus102, however, for example, the positioning apparatus described in the second embodiment through the seventh embodiment may be employed. In the second example given inFIG. 21, the positioning apparatus described in the second embodiment through the seventh embodiment may be employed instead of the positioning apparatus of the first embodiment.

(2) In addition to the above-described positioning apparatuses101,102, an exclusive clamping means capable of pressing the supported surface2aof the work pallet2against the support surface1aof the base plate1may be provided in the first example inFIG. 20. This construction is also applicable to the second example inFIG. 21.

(3) The combination of the first block and the second block may be a combination of a table of a machine tool and a work pallet, a- combination of a work pallet and a jig base, a combination of a jig base and a work piece, or a combination of a working jig such as a welding jig and a working article such as a work piece, instead of the exemplified combination of the base plate1and the work pallet2. Further, the combination may be a set of a board of an injection molding machine or of a pressing machine and a mold. In addition, the present invention is applicable to positioning of a work piece, a tool and the like used in various processing machines such as a laser beam machine and an electric discharge machine.