Workpiece holding device

Abstract

The device disclosed herein is a workpiece holding device (10) for holding a held portion (110) at an axial end of a cylindrical workpiece (100). The workpiece holding device (10) comprises: a circular core component (32) abutting against the inner peripheral surface of the held portion (110) of the workpiece (100); a pressing component (33) pressing the outer peripheral surface of the held portion (110) of the workpiece (100) radially inward; and a centering component (44) allowing the core component (32) to move radially according to the magnitude and direction of the pressing force when the pressing component (33) acts.

Description

Technical Field

[0001] The present invention relates to a workpiece holding device. Background Art

[0002] As a functional component for scraping off the hard carbon accumulated on the piston in a diesel engine, etc., a carbon scraper ring is used. The carbon scraper ring is installed on the upper part of the cylinder liner in the engine (the top dead center position of the piston top land) and scrapes off the hard carbon when the piston rises. The carbon scraper ring that performs this function is sometimes required to be thin-walled.

[0003] Various devices have been proposed for producing thin-walled metal ring-shaped parts such as scraper rings (see Patent Documents 1 and 2, etc.), for example, a device as described below is used: the device is used to clamp and cantilever support the end of a thin-walled cylindrical workpiece, and cut off the unsupported side (product portion) in sequence by cutting processing, etc. to produce, for example, 10 to 20 rings. In such a device, it is particularly important to clamp the workpiece in a manner that does not cause deformation, and to prevent vibration during processing, etc.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 9-066401

[0007] Patent Document 2: Japanese Patent No. 4522108 Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] However, in reality, when clamping a particularly thin-walled material such as a pipe, the workpiece may be deformed, which may affect the roundness of the processed ring. This is particularly true when the workpiece is thin-walled. In addition, if the overhang of the workpiece supported by the cantilever is large, vibration is likely to occur during processing, and it is often difficult to ensure processing accuracy. On the other hand, if a dedicated chuck is manufactured, it may become a very complex structure and become expensive.

[0010] As a method for dealing with these problems, it is considered to split the processing steps (for example, (1) outer diameter processing → inner diameter processing → cutting → one side chamfering processing → other side chamfering processing, a total of five clamping, or (2) cutting → outer diameter processing → inner diameter processing → one side chamfering processing → other side chamfering processing, a total of five clamping, etc., rather than cutting out a predetermined number of rings from the workpiece by one clamping (one clamping (one chuck)). However, when the processing steps are split, it is difficult to ensure the accuracy of the inner chamfer, inner and outer diameter coaxiality, roundness, etc. due to the influence of the clamping accuracy.

[0011] Therefore, an object of the present invention is to provide a workpiece holding device capable of processing a thin-walled cylindrical workpiece with higher precision.

[0012] Technical solutions for solving technical problems

[0013] One aspect of the present invention relates to a workpiece holding device, which is a device for holding a held portion at an axial end of a cylindrical workpiece, and comprises: a circular core component that abuts against the inner circumferential surface of the held portion of the workpiece; a pressing component that presses the outer circumferential surface of the held portion of the workpiece radially inward; and an aligning component that allows the core component to move radially according to the size and direction of the pressing force when the pressing force of the pressing component is applied.

[0014] In a workpiece holding device that performs cantilever support by pressing and clamping the outer circumference and inner circumference of the axial end of the workpiece by a pressing member and a core member, if the workpiece is not a perfect circle or has an uneven thickness, the processing accuracy may be affected, and the thinner the workpiece, the more serious this situation is. In this regard, in the workpiece holding device as described above, the core member moves in the radial direction according to the size and direction of the pressing force of the pressing member from the outside, thereby achieving balance (for position correction of each member and the workpiece into concentric circles, and uniformization / homogenization of the distribution of the pressing force), suppressing deformation of the workpiece during clamping and vibration during processing. Accordingly, thin-walled cylindrical workpieces can be processed with higher precision.

[0015] In addition, according to the workpiece holding device of the above aspect, the entire workpiece can be processed with excellent clamping accuracy in one time without splitting the processing steps. Therefore, it will not be involved in the reduction of accuracy caused by the influence that may occur each time clamping (deviation, deviation of the workpiece, etc.).

[0016] In the workpiece holding device of the above aspect, the centering member may be formed of an elastic member that is deformed according to the magnitude and direction of the pressing force of the pressing member.

[0017] The workpiece holding device of the above aspect may further include a mounting bolt for mounting the core member at a predetermined position of the workpiece holding device, and a sleeve-shaped elastic member disposed around the mounting bolt may be used as an aligning member.

[0018] The sleeve-shaped elastic member in the workpiece holding device of the above aspect may be made of resin, rubber, or silicone.

[0019] The mounting bolt in the workpiece holding device of the aspect described above may be a shoulder bolt inserted into a through hole provided in the core member, and the elastic member may be formed to match the shape of a gap between the through hole and the mounting bolt.

[0020] A plurality of members may be arranged at equal intervals in the circumferential direction as the pressing members in the workpiece holding device of the above aspect.

[0021] In the workpiece holding device according to the above aspect, the pressing member may include a clamper portion that increases the frictional force between the pressing member and the held portion of the workpiece.

[0022] In the workpiece holding device according to the above aspect, a portion of the peripheral surface of the core member that comes into contact with the inner peripheral surface of the workpiece may be tapered.

[0023] In the workpiece holding device of the aspect described above, the held portion of the workpiece may be a portion other than the portion that becomes the final product, and the workpiece having a tapered portion pre-machined on the inner circumferential surface of the held portion to match the tapered circumferential surface of the core component may be the holding object.

[0024] The workpiece holding device according to the above aspect may further include: a device for drawing in the workpiece in the axial direction; and an inclined wall surface for causing a component of force directed toward the radial inner side of the workpiece to act on the pressing member in accordance with the drawing of the drawing device.

[0025] Effects of the Invention

[0026] According to the present invention, a thin-walled cylindrical workpiece can be processed with higher precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a cross-sectional view showing one embodiment of a workpiece holding device.

[0028] Figure 2 This is a diagram showing a clamp portion of a workpiece holding device and a workpiece held by the clamp portion as viewed from the front end portion side of the workpiece.

[0029] Figure 3 is a longitudinal sectional view showing the clamping portion of the workpiece holding device in a state of holding the workpiece, which is equivalent to Figure 2 The accompanying drawing is a cross-sectional view taken along line III-III in FIG.

[0030] Figure 4 It is enlarged to show Figure 3 FIG. 2 is a diagram showing the periphery of a claw member of a clamping portion of a workpiece holding device.

[0031] Figure 5 It is a longitudinal sectional view showing the clamping portion of the workpiece holding device in a state where the clamping of the claw members is released.

[0032] Figure 6 It is enlarged to show Figure 5 FIG. 2 is a diagram showing the periphery of a claw member of a clamping portion of a workpiece holding device.

[0033] Figure 7 This is a longitudinal sectional view showing the clamping portion of the workpiece holding device in a state where the workpiece is held and the core member is moved in the radial direction.

[0034] Figure 8 It is enlarged to show Figure 7 FIG. 2 is a diagram showing the periphery of a claw member and an elastic member (centering member) of a clamping portion of a workpiece holding device shown.

[0035] Fig. 9 It is enlarged to show Figure 8 A diagram of a portion of (a circled portion with reference numeral A) in FIG. DETAILED DESCRIPTION

[0036] Next, the configuration of the present invention will be described in detail based on an example of the embodiment shown in the accompanying drawings (refer to Figures 1 to 9 ).

[0037] Figure 1 The workpiece holding device 10 shown in the figure is a device for holding a held portion 110 at a base end portion 102 of a workpiece 100. The workpiece 100 held by the device is a cylindrical thin-walled workpiece, and its product portion (the portion to be processed into a product) 120 is cut out sequentially from the front end portion 101 side while being held, and processed into a thin-walled metal ring-shaped member 200 such as a scraper carbon ring (in Figure 1 It should be noted that, for the sake of convenience, in this specification, along the axial direction of the workpiece 100 held by the workpiece holding device 10, the side of the front end portion 101 is referred to as the "front end side", and the side of the base end portion 102 is referred to as the "base end side" (refer to Figure 1 In addition, the virtual center axis when the workpiece 100 is held by the workpiece holding device 10 is represented by the reference symbol C (refer to Figure 1 wait).

[0038] The workpiece holding device 10 of the present embodiment is composed of a device main body 20 and a clamping part 30 (see Figure 1 The device body 20 includes a hydraulic introduction device (in the case of a workpiece 100) for introducing the clamping portion 30 to the base end side (the side having the device body 20) via the tube 24 along the axial direction of the workpiece 100. Figure 1 As such an introduction device 21, a known device used in the past can be applied (its detailed description is omitted in this specification). It should be noted that reference numeral 23 is a pipe for supplying cutting fluid to flow toward the front end side when the workpiece 100 is processed so as to cause the chips on the inner periphery of the workpiece 100 to flow out (refer to Figure 1 wait).

[0039] The device body 20 has an inclined wall surface 22 (see FIG. Figure 1 The inclined wall surface 22 is formed of a surface that is narrowed toward the base end and has a smaller diameter, for example, a tapered surface.

[0040] The clamping part 30 is provided to clamp and hold the workpiece 100, and can be introduced to the base end side by the introduction device 21. The clamping part 30 in the workpiece holding device 10 of this embodiment includes a base member 31, a core member 32, a claw member 33, a workpiece holder 34, an intermediate member 35, a stopper 36, a mounting bolt 42, an elastic member 44, etc. (refer to Figure 2 , Figure 3 wait).

[0041] The base member 31 is mounted and fixed to the device main body 20 (see Figure 1 The core member 32 is attached to the base member 31 in a state where it can move relative to the base member 31 in the radial direction (direction perpendicular to the virtual central axis C).

[0042] The core component 32 is a component that contacts the inner circumference of the held portion 110 of the workpiece 100 and is circular when viewed from the axial direction. In the present embodiment, a conical core is used in which the portion of the circumferential surface 32P of the core component 32 that contacts the inner circumferential surface of the workpiece 100 is formed into a conical shape with a larger diameter toward the base end (see FIG. Figure 1 The workpiece 100 can be easily assembled and disassembled relative to the core component 32 compared to a mating core having a uniform diameter. It should be noted that the workpiece 100 may also be a workpiece having a conical portion 100t pre-processed on the inner circumference of the retained portion 110 to match the conical circumferential surface 32P of the core component 32 (see Figure 8 By utilizing the wedge action of the introduction device 21 and the inclined wall surface 22 as in this embodiment, the core member 32 can be reliably brought into contact with the tapered portion 100t during clamping. The core member 32 is provided with a through hole 32H (see Figure 5 wait).

[0043] The claw member 33 is a member that functions as a pressing member that presses the outer peripheral surface of the held portion 110 of the workpiece 100 radially inward, and a plurality (for example, three) of the claw members 33 are arranged at equal intervals (every 120°) in the circumferential direction (see Figure 2 ). Each claw member 33 is provided so as to be movable in the radial direction by a claw guide (not shown) formed on the intermediate member 35 (see Figure 2 Each of these claw members 33 is configured to be linked to the intermediate member 35 (see Figure 2 , Figure 3 As the clamping portion 30 is introduced into the device 21 and introduced into the device main body 20 side, it is subjected to a radially inward force due to the wedge action of the inclined wall surface 22, pressing the workpiece 100 with a greater force (refer to Figure 4 wait).

[0044] It should be noted that in this embodiment, the claw adopts a two-forked claw member 33, so Figure 7 In the longitudinal sectional view, the mounting bolt 33A of the claw part 33 and the hole portion 33B for passing the mounting bolt 33A are shown, but the portion where the claw part 33 abuts against the outer peripheral surface of the workpiece 100 is not shown, so it is difficult to understand. However, in fact, the claw part 33 abuts against the outer peripheral surface of the workpiece 100 in the circumferentially adjacent portions of the hole portion 33B.

[0045] The workpiece holder (holder part) 34 is a member that increases the holding force of the workpiece 100 at the clamping part 30. In the present embodiment, the workpiece holder 34 is configured to increase the friction force and suppress slippage during rotation by moving the carbide tip provided inside or near the claw member 33 radially inward and pressing the end thereof against the outer peripheral surface of the workpiece 100 (see Figure 1 wait).

[0046] As described above, the intermediate member 35 is a member that causes a radially inward force component to act on the claw member 33 due to the wedge action of the inclined wall surface 22 as the clamping portion 30 is introduced into the device 21 and introduced into the device main body 20 side (see Figure 4 wait).

[0047] The stopper 36 is a member provided at a position where the edge 102E on the base end 102 side of the workpiece 100 hits, and defines the axial position of the workpiece 100 when the base end 102 of the workpiece 100 is inserted between the core member 32 and the claw member 33. In the present embodiment, a force is applied to the front end 101 of the workpiece 100, for example, toward the base end 102 by a force applying device (not shown) composed of a spring, a contact plate, etc., so that the edge 102E of the workpiece 100 in a state not clamped by the clamping portion 30 contacts the stopper 36, thereby defining the axial position of the workpiece 100 and maintaining its posture. It should be noted that when the clamping portion 30 is introduced toward the base end side (the side having the device main body 20) with the axial position of the workpiece 100 being defined by the stopper 36, and the workpiece 100 is clamped by the claw member 33 and the core member 32 using a wedge action, the stopper 36 moves toward the base end side, and the edge portion 102E is separated from the stopper 36 (see FIG. Figure 3 , Figure 4). In addition, in the process of moving the clamping part 30 toward the front end to relieve the clamping force caused by the wedge action in order to remove the workpiece 100, there is a case where the stopper 36 hits the edge 102E and pushes it toward the front end (refer to Figure 5 , Figure 6 ).

[0048] The mounting bolts 42 are bolts for mounting the core member 32 on the base member 31. In the present embodiment, a plurality of (for example, three) mounting bolts 42 and through holes 32H for passing the mounting bolts 42 are arranged at equal intervals (every 60° with respect to each claw member 33) in the circumferential direction without overlapping with the claw members 33 (see FIG. Figure 2 , Figure 5 As the mounting bolt 42, a shoulder bolt may be used. In the present embodiment, a shoulder bolt in which the threaded portion 42a is screwed into the threaded hole 31H of the base member 31 and the shoulder portion 42b contacts the end surface around the threaded hole 31H of the base member 31 is used as the mounting bolt 42 (see Figure 1 , Figure 7 to Figure 9 ) According to such a mounting bolt 42, it is easy to make the mounting depth, tightening torque, etc. of the bolt uniform.

[0049] The through hole 32H of the core member 32 is provided to allow the threaded portion 42a of the mounting bolt 42 to pass therethrough and to accommodate the shaft portion 42c and the head portion 42d. In the present embodiment, the through hole 32H is formed into a hole with a shoulder shape matching the shape of the shaft portion 42c and the head portion 42d of the mounting bolt 42 and having an inner diameter larger than the shaft portion 42c and the head portion 42d to a certain extent, so that a predetermined gap is formed between the mounting bolt 42 and the through hole 32H (see Fig. 9 An elastic member 44 is provided in the gap.

[0050] The elastic member 44 is provided as an example of a deformable centering member, and when a pressing force is applied to the held portion 110 of the workpiece 100 from the outer peripheral side by the claw member 33, the centering member allows the core member 32 to move in the radial direction according to the magnitude and direction of the pressing force. The elastic member 44 of this embodiment is formed into a sleeve shape and is arranged around the mounting bolt 42. In addition, corresponding to the shoulder shape of the mounting bolt 42 and the through hole 32H, in this embodiment, two kinds of sleeve-shaped elastic members with different diameters are arranged around the mounting bolt 42 (see Fig. 9 One of the two sleeve-shaped elastic members is sandwiched between the shoulder of the through hole 32H and the head 42d of the mounting bolt 42, and functions as a base (see Fig. 9 ).

[0051] As described above, the workpiece holding device 10 of the present embodiment realizes the centering function as follows by the elastic member 44 that is elastically deformable and flexible. That is, when the clamping portion 30 is introduced by the introduction device 21, the claw member 33 exerts a pressing force from the outer periphery of the workpiece 100 by utilizing the wedge effect brought about by the inclined wall surface 22, and the held portion 110 of the workpiece 100 is clamped by the claw member 33 and the core member 32 (see Figure 4 At this time, if the pressing force on the workpiece 100 between the claw member 33 and the core member 32 is uniform, there will be no significant effect. However, if the pressing force is uneven due to poor machining accuracy of the workpiece 100, a radial force is applied to the core member 32 in accordance with the unevenness. At this time, in the workpiece holding device 10, the elastic member 44 is elastically deformed by the force, and the core member 32 moves radially by the correction amount a (see Figure 8 ) corresponding amount, thereby exerting the so-called balancing function (for position correction of each component and workpiece into a concentric circle, and uniformity of the distribution of the pressing force) (refer to Figure 7 to Figure 9 ). In the workpiece holding device 10 that performs cantilever support by clamping the end (base end 102) of the workpiece 100 by the claw member 33 and the core member 32 as in the present embodiment, when the workpiece 100 is not a perfect circle or the thickness is uneven, it sometimes affects the processing accuracy. However, in this regard, according to the workpiece holding device 10 with the balancing function as described above, it is possible to eliminate such influence as much as possible, and suppress the deformation of the workpiece 100 during clamping and the vibration during processing. In addition, in the case of cantilever support, if it is desired to suppress the risk of vibration and workpiece falling off during processing, it is necessary to increase the clamping force (pressing force) and workpiece rigidity. However, according to the workpiece holding device 10 of the present embodiment with the core member 32, even if the clamping force is increased, the deformation of the workpiece 100 can be suppressed, and the workpiece 100 can be firmly held without vibration. According to the above, thin-walled cylindrical workpieces can be processed with higher precision. In addition, as a previous method for processing thin-walled cylindrical workpieces with higher precision, there is a method of splitting the processing steps (repeatedly clamping and cutting rings instead of cutting a predetermined number of rings from the workpiece by a single clamping). However, according to the workpiece holding device 10 of this embodiment, even if the processing steps are not split like this method, thin-walled cylindrical workpieces can be processed with higher precision by only a single clamping.

[0052] In addition, according to the workpiece holding device 10 such as the present embodiment constructed as described above, (i) a thin-walled cylindrical workpiece 100 can be processed with higher precision, thereby suppressing the deformation of a metal annular component 200 such as a carbon scraper ring manufactured by workpiece processing and ensuring roundness; (ii) the deformation of the workpiece 100 during clamping and the vibration during processing can be suppressed, thereby enabling a large number of metal annular components 200 to be efficiently cut out from a workpiece 100 having a longer total length than before; and (iii) by moving the introduction device 21 in the axial direction, the workpiece 100 can be automatically disassembled and assembled using the claw component 33 of the mechanism that moves obliquely in accordance with the inclination of the inclined wall surface 22.

[0053] It should be noted that the above embodiment is an example of a preferred implementation of the present invention, but is not limited thereto, and various modifications can be made within the scope of the present invention. For example, in the above embodiment, as an example of a centering component, an elastic component 44 provided around the mounting bolt 42 is shown, but the shape, material, and structure of the elastic component 44 are only a preferred example, and it is needless to say that the elastic component 44 can be applied to other components that achieve the same function, such as rubber or silicone components.

[0054] Industrial Applicability

[0055] The present invention is suitable for application to various workpiece holding devices, including a workpiece holding device in a robot, and devices including NC and a loader.

[0056] Description of Reference Numerals

[0057] 10…Workpiece holding device

[0058] 20…Device body

[0059] 21…Introduction device

[0060] 22…Sloped wall

[0061] 23…Liquid supply pipe

[0062] 24…Tube

[0063] 30…Clamping part

[0064] 31…Base components

[0065] 31H…Threaded hole for mounting bolts

[0066] 32…Core components

[0067] 32H…Through hole for mounting bolts to pass through

[0068] 32P…Circumference

[0069] 33…Claw member (pressing member)

[0070] 33A…Mounting bolts

[0071] 33B…Hole

[0072] 34…Workpiece holder (holder part)

[0073] 35…Intermediate parts

[0074] 36…Stop

[0075] 42…Mounting bolts

[0076] 42a…Threaded part

[0077] 42b…Shoulder

[0078] 42c…Shaft

[0079] 42d…Head

[0080] 44…Elastic component (aligning component)

[0081] 100...Workpieces

[0082] 101…Front end

[0083] 102…base end

[0084] 102E…Edge on the base end side

[0085] 100t…cone

[0086] 110…Retained portion

[0087] 120…Products Department

[0088] 200…Carbon scraping ring (metal ring-shaped component as the final product)

[0089] a…correction amount

[0090] C…center axis.

Claims

1. A workpiece holding device for holding a held portion at an axial end portion of a cylindrical workpiece, the workpiece holding device comprising: a circular core member abutting against the inner peripheral surface of the held portion of the workpiece; A pressing member presses the outer peripheral surface of the held portion of the workpiece radially inward; and The centering member allows the core member to move in the radial direction according to the magnitude and direction of the pressing force when the pressing force of the pressing member acts on the core member. The centering member is composed of an elastic member that is deformed according to the magnitude and direction of the pressing force of the pressing member. The workpiece holding device further comprises a mounting bolt, and the mounting bolt is used to mount the core member at a predetermined position of the workpiece holding device. A sleeve-shaped elastic member disposed around the mounting bolt is used as the alignment member.

2. The workpiece holding device according to claim 1, wherein: The sleeve-shaped elastic member is made of resin, rubber or silicone.

3. The workpiece holding device according to claim 2, wherein: The mounting bolt is a shoulder bolt inserted into a through hole provided in the core member, and the elastic member is formed to match the shape of a gap between the through hole and the mounting bolt.

4. The workpiece holding device according to any one of claims 1 to 3, wherein: The workpiece holding device includes a plurality of the pressing members, and the plurality of pressing members are arranged at equal intervals in a circumferential direction.

5. The workpiece holding device according to claim 4, wherein: The pressing member includes a clamper portion that increases frictional force between the pressing member and the held portion of the workpiece.

6. The workpiece holding device according to any one of claims 1 to 3, wherein: A portion of the peripheral surface of the core member that contacts the inner peripheral surface of the workpiece is tapered.

7. The workpiece holding device according to claim 6, wherein: The held portion of the workpiece is a portion other than a portion that becomes a final product, and the workpiece having a tapered portion pre-processed on the inner peripheral surface of the held portion to match the tapered peripheral surface of the core member is a held object.

8. The workpiece holding device according to claim 6, wherein: The workpiece holding device further comprises: means for introducing said workpiece in an axial direction; and The inclined wall surface acts on the pressing member with a force component directed toward the radial inner side of the workpiece as the device for introducing the workpiece is introduced.

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