JP4393214B2 - Chuck device - Google Patents

Description

  The present invention relates to a chuck device for chucking a workpiece during lathe processing or the like, and particularly intended for a thin and fragile workpiece.

  As a conventional means for grasping thin and fragile workpieces without deformation, multiple cylinders of the same size are arranged radially around the axis of the chuck body, and the piston rods of the cylinders are operated with a pressure fluid of the same pressure. Thus, there is a chuck device that grasps a workpiece with an equal force from each direction. (For example, refer to Patent Document 1).

  In this chuck device, the piston rods of the cylinders arranged in a large number in a radial pattern do not have a centering function like the claws of the competition chuck, so that, for example, a work guide is roughly provided to center the work. A centering method, a method of incorporating a centering chuck such as a collet chuck, or other centering methods are appropriately employed.

  For example, as shown in FIG. 4, with a large number of radially arranged piston rods, the outer periphery of the workpiece, which is on the same circumference as that to be clamped, is arranged in three equally spaced locations on the piston rod, and the thin portion of the workpiece is deformed. A technique for centering without any problems is disclosed.

As shown in the drawing, the chuck device has a centering method in which a chuck body 5 fixed concentrically to a spindle center c (hereinafter referred to as an axis c) of a lathe has a plurality of radial directions from the axis c. A cylinder is provided at a position of an equal angle (equal direction) around the axis. Of these, three cylinders positioned at equal angles around the axis c are referred to as centering cylinders 1 and the other cylinders are referred to as clamping cylinders 2. One end centering rod L ₁ to the piston P ₁ of the centering cylinder 1, provided with one end clamp rod L ₂ to the piston P ₂ of the clamping cylinder 2, together with the piston P _1, P _2, respectively, the The rods L ₁ and L ₂ can be projected and retracted inward from the inner peripheral surface of the cylindrical hole 6 in the front portion of the chuck body 5 where the workpiece W is disposed.

The centering cylinder 1 and the clamping cylinder 2 communicate with fluid supply means (not shown) via the fluid circuit 8, respectively, and the pistons P ₁ and P ₂ are pressurized by supplying the working fluid to the cylinders 1 and 2, respectively. Thus, the rods L ₁ and L ₂ advance inward in the radial direction of the main shaft. Further, the three centering cylinder 1 is configured to operate by a fluid circuit 7 is provided with a centering cylinder device 3 for imparting the same biasing force by a spring S _3.

When grasping the workpiece W with this chuck device, the workpiece W is first centered. In this method, the hydraulic pressure of the fluid circuit 8 is released, and the clamping piston P ₂ and the clamping rod L ₂ are retracted radially outward by the biasing force of the spring S ₂ . Then, by supplying the hydraulic fluid to the centering cylinder unit 3 through the fluid circuit 7, to move the piston rod L ₃ to the left against the spring S ₃ of the centering cylinder device 3.

In this state, the workpiece W is inserted into the hole 6 from the front surface of the chuck body 5, and the workpiece W is temporarily placed in contact with the bottom surface 4 in the hole 6. Next, when the fluid circuit 7 of the centering cylinder device 3 is released, the piston rod L ₃ of the cylinder device 3 moves to the right side by the biasing force of the spring S ₃ . By this movement, the piston rod L ′ ₁ and the piston P ₁ advance toward the inside in the radial direction via the inclined surfaces 9a and 9b, and the centering rod L ₁ integrated with the piston P ₁ moves the workpiece W around the outer periphery 3 thereof. It is held with equal force from the equal angle. After this holding, if the centering rod L ₁ and the clamping rod L ₂ are operated through the fluid circuit 8, the periphery of the workpiece W can be grasped with the entire circumference. (For example, refer to Patent Document 2).

In the multiple cylinders arranged radially, it is possible to increase the distance (stroke) that the piston rod slides by increasing the cylinder length. However, the piston rod having the centering function has functional limitations. In order to receive, the stroke must be short. For this reason, a cartridge type auxiliary pin is appropriately attached to the tip of the piston rod for a workpiece having a different grasping diameter.
JP 7-256505 A JP-A-10-249614

As described above, the stroke centering rod L _1, the inclined surface 9a, because they are limited in range capable of sliding 9b, in this chucking apparatus, chat a workpiece W having a diameter exceeding the range of the stroke I can't king. To accommodate the workpiece W having a diameter exceeding the stroke, or replaced each time the centering rod L ₁ in different things lengths with centering piston P _1, or be like replacing all chuck body 5 itself I must.

However, in order to replace the centering rod L ₁ with a different length, it is necessary to extract the piston P ₁ and the rod L ₁ from the cylinder 1, and this replacement involves the discharge of the pressure fluid. Therefore, the work is complicated. Repeating the attachment / detachment is liable to cause wear and damage to the parts, and is not preferable for maintaining the accuracy of centering. Moreover, since the replacement of the chuck body 5 is a very complicated operation, it is not realistic to perform it frequently.

In order to substantially increase the stroke of the centering rod L ₁ without detaching parts, the height difference in the radial direction of the inclined surface 9a as the sliding surface (shown in FIG. 5 (a)). A method of increasing the height H) in advance and increasing the diameter range of the workpiece W that can be handled by the same rod L ₁ is also conceivable.

For example, in order to ensure a large height H, the slope of the inclined surface 9a is increased, that is, a method of causing the inclination to the side orthogonal to the main axis as shown in FIGS. 5 (a) to 5 (b). However, according to this approach, a slight lateral movement of the rod L ₃ in the figure, so that the piston P ₁ and the rod L _'1 integral greatly advance and retreat up and down. For this reason, a slight error in the transmission of the urging force by the spring S ₃ and the piston rod L ₃ greatly affects the advance / retreat amount of the rod L ′ ₁ . Further, the slope change, like as FIG. 5 (a) to (b), since weakening the biasing force F ₁ acting on the rod L _'1, the centering accuracy of the workpiece W is not preferable.

Further, the inclined surface 5 as shown in (c), to increase the lateral extension to the height H to the (axial direction of the piston rod L ₃₎ with the same inclination as in FIGS. 5 (a) At the same time, by increasing the stroke S in the lateral direction of the piston rod L _3, a method of increasing the range in which the rod L ′ ₁ can advance and retreat (the stroke in the height H direction) can be considered. However, according to this method, the amount of movement of the rod L _{3 as} the rod L ′ ₁ advances and retracts, that is, the amount of expansion and contraction of the spring S ₃ also increases. Large expansion and contraction of such spring S _3, together with not preferable to maintain a constant biasing force at the time of centering, since the depth of the chuck body 5 is increased, device becomes large. It is not preferable to increase the size of the apparatus. For this reason, it was difficult to deal with workpieces W of different diameters in a wide range with the same chuck device while maintaining accuracy without increasing the size of the device.

  Accordingly, an object of the present invention is to make it possible to easily chuck workpieces having different diameters with a simple structure using the same chuck device.

  In order to solve the above-described problems, the present invention provides the chuck body center side ends of three centering rods used for centering on the outer periphery of a tapered cone provided so as to be able to advance and retract in the main shaft direction of the chuck body. The rod is slid through three inclined surfaces, and the rod is urged outward by the advance and retreat of the tapered cone. The radial distance from the axis of the tapered cone to the inclined surface can be changed by replacing the tapered cone. It was. If the position of the inclined surface in the radial direction from the axial center changes, the range in the radial direction in which the centering rod can advance and retreat also changes, so that workpieces having different diameters can be chucked.

  Specifically, first, a cylindrical chuck body fixed concentrically to the center of the main axis of the lathe, and a plurality of cylinders are equally spaced in the radial direction along one circumference of a cross section perpendicular to the axis. In the cylinder, a piston is built in such a manner that the piston can be moved forward and backward, and a rod that moves integrally with the piston is provided. It is a device that holds the peripheral surface.

  Next, among the plurality of cylinders, three equally-spaced cylinders are used as centering cylinders and the other is used as a clamping cylinder. The piston rods are respectively provided so as to be able to advance and retract integrally with the centering piston. In the chuck body, a cylinder device having a piping other than the centering cylinder and the clamping cylinder, or a cylindrical shape concentric with the end of the shaft that moves forward / backward along the center of the main shaft using a rotary cylinder as a drive source. Attached to the shaft is a taper cone that is provided with an opening hole, and the outer periphery of the cylindrical shaft that fits into the hole is inclined at an equal distance from the central axis so as to be along the inclined surface of the piston rod. The configuration is as follows.

  Further, by retracting the taper cone, the rods of the three centering pistons spread outwardly through the both inclined surfaces to center the workpiece, and then hydraulic pressure is applied to all the cylinders to The rod is advanced to hold the workpiece with the same pressing pressure, and then the taper cone is advanced to remove the centering force applied to the three centering pistons and keep the entire inner peripheral surface of the workpiece equal. Grasp by force.

  In this way, each rod of the three centering cylinders can be urged all at once with one taper cone, so that the configuration of the device is simplified, and the inclined surface for controlling the rod is integrated into one taper cone. Therefore, the trouble of the desorption is saved.

  In the chuck device for thin-walled / brittle workpieces having the above-mentioned configuration, the taper cone adopts a configuration capable of centering and holding a workpiece having a different inner diameter by selecting a taper cone having a different distance from the central axis to the inclined surface. obtain.

  In this way, several cones with different distances from the inclined surface position, that is, the distance from the axial center of the cone central axis to the inclined surface are prepared, and the cones are adjusted according to the diameter and shape of the workpiece to be chucked. Can be moved in the radial direction of the main axis of the rod of the centering cylinder that slides on the inclined surface. For this reason, it is possible to deal with workpieces having different diameters by replacing only the tapered cone using the same chuck body without removing and replacing the piston and rod of the centering cylinder from the chuck body.

  Since the present invention is configured as described above, it can easily cope with chucking of workpieces having greatly different diameters with the same chuck device.

1 to 3 show an embodiment of a chuck device according to the present invention, in which a chuck body 10 fixed concentrically to a main spindle center c (hereinafter referred to as an axis c) of a lathe, as shown in FIG. Twelve cylinders facing radially outward from the axis c are provided at equal angles around the axis. Of these, the three cylinders are positioned at an equal angle around the axis c to be a centering cylinder 11 and the other cylinders are clamp cylinders 12. As shown in FIGS. 1 and 2, a centering rod L ₁₁ is provided at the outer end of the piston P ₁₁ of the centering cylinder 11, and a clamping rod L ₁₂ is provided at the outer end of the piston P ₁₂ of the clamping cylinder 12. The rods L ₁₁ and L ₁₂ are provided integrally with each other and move in conjunction with the pistons P ₁₁ and P ₁₂ .

As shown in FIG. 1, the centering cylinder 11 and the clamping cylinder 12 are provided with inner cylinder chambers 11a and 12a and outer cylinder chambers 11b and 12b with pistons P ₁₁ and P ₁₂ interposed therebetween, respectively. The inner cylinder chambers 11a and 12a are connected to the fluid circuit 18, and the outer cylinder chambers 11b and 12b are connected to the fluid circuit 16, respectively. The circuits 16 and 18 communicate separately with fluid supply means (not shown) that operate independently, and supply and discharge the working fluid to and from the centering cylinders 11 and the clamp cylinders 12 by the fluid supply means. It is possible.

With the fluid circuit 18 released, the working fluid is supplied to the outer cylinder chambers 11b and 12b by the fluid circuit 16 to pressurize the rods L ₁₁ and L ₁₂ of the pistons P ₁₁ and P _12. The pistons P ₁₁ and P ₁₂ are moved backward inward, and the working fluid is supplied to the inner cylinder chambers 11a and 12a and pressurized by the fluid circuit 18 with the fluid circuit 16 released. Rods L ₁₁ and L ₁₂ are advanced outward in the radial direction.

Further, the three centering cylinders 11 are provided with a centering cylinder device 13 by piping different from the fluid circuits 16 and 18, and the shaft L ₁₃ of the centering cylinder device ₁₃ is the axis of the chuck body 10. It is arranged concentrically with c and orthogonal to the rod L ₁₁ of the centering cylinder 11.

As shown in FIG. 1, the shaft L ₁₃ is provided with a fluid circuit 17 for supplying a working fluid separately from the fluid circuits 16 and 18 in the outer cylinder chamber 13 a of the centering cylinder device 13. The shaft L ₁₃ can be pressurized toward the front side by the supplied fluid pressure, and an urging force is applied to the inner cylinder chamber 13 b of the cylinder 13 in a direction opposite to the pressurizing direction. A spring 25 is arranged. Fluid pressure supplied to the centering cylinder 13, and by the urging force of the spring 25, the shaft L ₁₃ is advanced along the axis c, is adapted to retract.

A cylindrical opening hole 23 concentric with the axial center c is provided at the end of the shaft L _{13 on} the front surface side of the chuck body 10, and a tapered cone 20 having a cylindrical shaft that fits into the hole 23 is fitted into the hole 23. , fixed to the shaft L _13. The taper cone 20 is attached to and removed from the shaft L ₁₃ via a bolt 22.

The mounting portion is configured such that the front end of the shaft L ₁₃ of the centering cylinder device 13 is exposed toward the front side in the opening hole 23, and a bolt hole 26 is provided with the exposed portion as a cone mounting portion. Yes. Further, the piston P ₁₁ of the centering cylinder 11, the rod 21 end provided integrally on the center side (inner side) is adapted to protrude into the opening hole 23.

This opening hole inside 23 and the cone 20 is inserted from the front side, a bolt 22 is screwed into the bolt hole 26, the tapered cone 20 is detachably attached concentrically with the shaft L _13. At this time, since the shaft L ₁₃ is provided with the anti-rotation pin 24, the shaft L ₁₃ does not rotate carelessly when being attached or detached.

As described above, the tapered cone 20 has a cylindrical shaft shape that fits in the hole 23, and as the shaft L ₁₃ moves in the axial direction, its peripheral surface slides on the inner wall of the hole 23 and is concentric. It is designed to move in the axial direction while maintaining the state. A tapered surface directed toward the end of the cone 20 near the end on the shaft L ₁₃ side is provided so that the outer diameter is slightly smaller as it approaches the end. Easy to insert inside.

  Further, the inclined surface 19 a of the cone 20 is provided on the outer peripheral surface of the cone 20, and the configuration thereof is directed toward the rods 21 of the three centering cylinders 11 protruding into the hole 23. A groove 20a is formed in the same direction as the axis c, and an inclined surface 19a is provided at the bottom of each of the three grooves 20a. The inclined surface 19a has a gradient in a direction away from the axis c as it approaches the front side of the chuck body 10 from the cylinder device 13 side, and has a gradient of the same angle with respect to the axis c. . The distance from the axis c of the inclined surface 19a is set such that all three inclined surfaces are equidistant in the cross section orthogonal to the axis c.

The inclined surface 19a is in contact with the inclined surface 19b of the piston rod 21 ends provided integrally with the piston P ₁₁ center side of the centering cylinder 11 (inner). Both inclined surfaces 19a, 19b, the surface to contact because the same gradient with respect to the axial direction of the spindle center, together with the shaft L ₁₃ moves forward and backward in the axial direction, the inclined surface 19b is sliding on the inclined surface 19a Then, the contact position moves on the inclined surface 19a.

In this sliding state, all of the inclined surface 19a, as long as 19b to each other is sliding, centering cylinder device 13, the inclined surface 19a rod for each center the same urging force through the L of the shaft L ₁₃ Functions to grant to ₁₁ . Another aspect of the centering rod L _11, the biased radially by (radial distance from the axis c) change in the contact position between the inclined surface 19a of the shaft L _13, for other centering Regardless of the position of the rod L ₁₁ in the radial direction, the rod L ₁₁ is independently biased with respect to the axis. Since an urging force can act independently on each piston rod L ₁₁ , the workpiece W can be maintained concentrically with the axis c.

When chucking, several tapered cones 20 having different positions of the inclined surface 19a (distance in the radial direction from the axis c of the inclined surface 19a) are prepared, and a predetermined cone according to the diameter of the workpiece W to be chucked is prepared. if selected and used 20, since also changes a range of the stroke of the rod L ₁₁ by the position of the inclined surface 19a is changed in the radial direction, the inner diameter of the holding portion of the workpiece W, the rod L ₁₁ It can be adjusted to fit within the stroke range.

Hereinafter, to explain the action when chucking the workpiece W, as shown in FIG. 1 and FIG. 2, first, a predetermined taper cone 20 attached to the shaft L _13, supplies the working fluid to the fluid circuit 17 out square and a piston P ₁₃ from the cylinder chamber 13a side pressurized, as indicated by an arrow a in FIG. 1, is moved towards the shaft L ₁₃ that moves together with the piston P ₁₃ on the right. For this movement, a small distance that does not reach the cap 27 provided on the front side of the opening hole 23 is sufficient.

The hydraulic pressure applied by the fluid circuit 17 remains unchanged, the hydraulic pressure of the fluid circuit 18 is released so that no hydraulic pressure is applied to the cylinder chambers 11a and 12a, and the working fluid is supplied to the fluid circuit 16 from the cylinder chambers 11b and 12b. The pistons P ₁₁ and P ₁₂ are pressurized inward as indicated by arrows B and C to retract the rods L ₁₁ and L ₁₂ inward, and then the hydraulic pressure of the fluid circuit 16 is also released.

In this state, from the front side of the chuck device 10, the workpiece W is fitted on the outer periphery 14 of the front portion of the chuck device by manual operation or a robot as shown by the chain line in the figure and brought into contact with the front surface 15 to be temporarily placed. Then, when the hydraulic pressure of the fluid circuit 17 of the centering cylinder device 13 is released, the shaft L ₁₃ of the cylinder device 13 is moved in the direction opposite to the arrow A in the figure by the urging force of the spring 25. This movement, the inclined surfaces 19a, the centering rod L ₁₁ through 19b is opposite the direction of arrow B in FIG, i.e. toward the radially outward advances with a uniform force, the rod L ₁₁ work Abutting on the inner circumferential surface of W and holding it from the position of an equally divided angle on the inner circumference, the axis of the workpiece W is made to coincide with the axis.

At this time, is set by the work W is deviated, the rod L ₁₁ not in close contact with the workpiece W in the three centering rods L ₁₁ is present, the reaction force that is biased to the three centering rods L ₁₁ that acts . Shaft L ₁₃ of the centering cylinder device 13 is advanced rod L ₁₁ so as to the same biasing force to cancel the difference between the reaction force acting on each of its centering rod L _11, and holds the aligning the workpiece W.

After the holding, centering cylinder 11 through the fluid circuit 18 and supplying the working fluid to the clamping cylinder 12, the centering rod L _11, clamping rod L ₁₂ is toward the radially outward arrow B, the C By operating in the opposite direction, the inner periphery of the workpiece W is clamped at a plurality of points while maintaining the concentric state.

At this time, even when the pressure of the working fluid by the fluid circuit 18 is increased so that the pressing force of the pistons P ₁₁ and P ₁₂ is larger than the urging force of the spring 25, the fluid circuit 18 moves to all the cylinder chambers 11 a and 12 a. Since the work W that is centered by the centering rod L ₁₁ is opened, all the delayed rods L ₁₂ are in contact with each other even if the timing at which the individual rods L ₁₂ contact the work W is misaligned. Until the pressing force is generated, the pressing force does not act on the preceding rods L ₁₁ and L ₁₂ . After all the rods L ₁₂ have contacted, an even pressing force acts on the workpiece W, so a large force is applied to the workpiece W locally, degrading centering accuracy, or degradation to roundness accuracy due to local workpiece distortion. The work W can hold the work inner periphery strongly while maintaining centering.

  For this reason, for example, even when there is a variation in the distance between the gripping surface of the workpiece W and the center, it is possible to clamp with uniform force while maintaining centering.

After this clamping, to supply again the working fluid in the fluid circuit 17, slightly moving the shaft L ₁₃ like the arrow A towards the front side, in the direction to cause a slight gap inclined surface 19a, between the 19b is allowed, by this movement, the pressure in the radially outwardly acting on the centering rod L ₁₁ through the inclined surface 19a is released. At this time, since the workpiece W is maintained by the pressurization of the rods L ₁₁ and L ₁₂ to the outside in the radial direction by the fluid circuit 18 continuously acting, the accuracy of the concentric state is maintained. Can do.

As a result, the rods L ₁₁ and L ₁₂ on which the same hydraulic pressure is applied with the same piston area hold the workpiece W with a flexible force from each direction, so that the thin-walled and fragile workpiece W is not deformed. can do. After the chuck body 10 is rotated and the predetermined turning and machining is completed by a lathe or the like, the hydraulic pressure of the fluid circuit 18 is released, and at the same time, the working fluid is supplied to the fluid circuit 16 so that the rods L ₁₁ and L ₁₂ are moved to the inside. The machined workpiece W is removed by moving it backward. At this time, when machining a workpiece W having a different diameter, for example, as shown in FIG. 3, the tapered cone 20 may be replaced with an object having a predetermined inclined surface 19 a position corresponding to the diameter of the workpiece W. Good.

In this embodiment, in order to hold the workpiece W, as shown in FIG. 2, the cylinder 11 and the cylinder 12 are arranged around the axis c at 12 equally angled positions. The number of cylinders 11 and 12 to be arranged is arbitrary as long as they are arranged at an equal angle with respect to the peripheral surface of the cylindrical thin workpiece, and around the axis c as long as it can be attached to the chuck body 10. If many are provided, the holding state is stabilized. Further, the number of centering cylinders 11 is not limited to three, and may be four or more. Further, as means for retracting the rods L ₁₁ and L ₁₂ of the cylinders 11 and ₁₂ toward the center in the radial direction, the action of fluid pressure may be used as in this embodiment, or the elasticity of a spring or the like. The urging force by the body may be used, and as the means for moving the shaft L ₁₃ forward and backward, the action of fluid pressure may be used as in this embodiment, or a drive source such as a rotary cylinder may be used. Other means such as use may be used.

The shape of the taper cone 20 is not limited to the cylindrical shaft shape as in this embodiment, and the cross-sectional shape in the direction orthogonal to the axis c is the same cross-sectional shape as the opening hole 23. As long as the two fit together, you are free. Here, the cylindrical shaft or the cylindrical shaft is a concept including a columnar shape whose cylindrical shaft end face is closed. Furthermore, slides on the inclined surface 19a of the shaft L ₁₃ of the centering cylinder device 13, the shape of the rod 21 end of the centering cylinder 11, as in this embodiment, a surface contact with the inclined surface 19a Sliding is stable with the inclined surface 19b having the same gradient. However, when stability is not particularly required, the inclined surface 19b having a different gradient, or any other shape that makes point contact or line contact with the inclined surface 19a can be used. It may be.

Cross-sectional view of one embodiment Side view of FIG. Cross-sectional view of another embodiment Cross section of conventional example 4A and 4B are explanatory views of the operation of the conventional example, in which FIG. 4A is an example of FIG. 4, FIG. 4B is an example in which the slope of the inclined surface of FIG. 4 is tightened, and FIG. Example of increasing the length of the inclined surface

Explanation of symbols

1, 11 Centering cylinder 2, 12 Clamping cylinder 3, 13 Centering cylinder device 5, 10 Chuck body 7, 8, 16, 17, 18 Fluid circuit 9a, 9b, 19a, 19b Inclined surface 14 Outer periphery 15 Front surface 20 Taper cone 23 Opening hole 24 Non-rotating pin 26 Bolt hole 27 Cap L ₁ , L ₁₁ Centering rod L ₂ , L ₁₂ Clamping rod L ₃ Piston rod L ₁₃ Shaft P ₁ , P ₁₁ Centering piston P ₂ , P ₁₂ Clamping piston _{S 1, S 2, S 3} , 25 spring

Claims (2)

A cylindrical chuck body ( 10 ) fixed concentrically to the center of the lathe spindle is provided with a plurality of cylinders ( 11, 12 ) at equal angles in the radial direction along one circumference of a section perpendicular to the axis. , a piston (P _11, P ₁₂₎ built to be able to advance and retreat the to its respective piston (P _11, P ₁₂₎ and providing a rod (L _11, L ₁₂₎ to move integrally with their respective cylinders (11, 12) together, by advancing the piston (P _11, P ₁₂₎ by the fluid pressure supplied to the respective cylinders (11, 12) outwardly, said rod (L _11, L ₁₂₎ distal the work (W) in peripheral In the chuck device for thin and brittle workpieces that hold the surface,
Wherein the plurality of cylinders (11, 12), arranged equally the three or more centering cylinder (11), the other as a clamping cylinder (12), the centering piston of the centering cylinder (11) ( P ₁₁ ) On the center side, piston rods ( 21 ) of the same length, each having an inclined surface ( 19b ) at the tip thereof, are provided to be able to advance and retreat integrally with the centering piston ( P ₁₁ ) ,
The chuck body (10), the centering cylinder (11), forward and along the spindle center cylinder device of another pipe (13), or a rotating cylinder as a drive source to the clamping cylinder (12) A concentric cylindrical opening hole ( 23 ) is provided at the end of the retreating shaft ( L ₁₃ ) , a taper cone (20) is fitted into the hole ( 23 ), and the peripheral surface of the taper cone (20) is the hole ( 23) The taper cone (20) moves along the center of the main shaft while maintaining a concentric state while sliding on the inner wall, and the taper cone (20) is the piston rod on the outer peripheral surface around the cylinder axis. a portion facing (21) is equal to the inclined surface of the distance from the central axis from one another along the inclined surface of the piston rod (21) (19b) (19a), the Mounting tapered cone (20) to the shaft (L _13), and detachable,
By retracting the taper cone (20) along the spindle center, via said two inclined surfaces (19a, 19b), spreads the rod (L ₁₁₎ of each centering piston (P ₁₁₎ outwardly workpiece ( W) after centering the workpiece with a rod (L _11, L ₁₂₎ to advance the by equal pressing force of all the pistons in addition to hydraulic pressure to all of the cylinders _{(11,12) (P 11, P} 12) ( W) holds, then held, by advancing the tapered cone (20), removal force of the centering said has been added to each centering piston (P _11), equal to the entire workpiece (W) in the peripheral surface A chuck device for thin and brittle workpieces with a centering function characterized by force. In chucking device for a thin-brittle workpiece according to claim 1, wherein the tape Paco chromatography emission (20) by selecting different taper cone (20) of the distance from the central axis to the inclined surface (19a), an inner diameter A chuck device for thin-walled / brittle workpieces, characterized in that it can hold a workpiece ( W ) of different thickness by centering.

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