Coupling mechanism and grinder comprising the same

Abstract

To couple a workpiece holding part which integrally rotatably holds a workpiece in a replaceable manner, with respect to an output shaft of a rotation drive source.SOLUTION: A coupling mechanism 9 interposes between a workpiece holding part 11 which integrally rotatably holds an annular workpiece W in a flat or an upright attitude and an output shaft 10 of a rotation drive source arranged coaxially with the workpiece holding part 11, to integrally rotatably couple in a separable state of the workpiece holding part 11 from the output shaft 10. This coupling mechanism 9 comprises a coupling attachment 12 fixed on the tip of the output shaft 10 to hold two clampers 13 capable of pivoting by a predetermined amount around a pivot shaft 16 in a horizontal direction and, by reciprocation of the clampers 13 within a pivotable range, a compression part 14 provided in the clamper 13 mutually transit between a retreat position not coming into contact with the workpiece holding part 11 and a restraining position for restraining by pressing the workpiece holding part 11 against the coupling attachment 12.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a coupling mechanism, and more particularly to a coupling mechanism that detachably couples a workpiece holder that holds a workpiece to an output shaft of a rotary drive source. [Background technology]

[0002] For example, Patent Document 1 listed below describes a grinding machine that grinds (centerless grinds) the peripheral surface of a workpiece with a circular cross section. In this grinding machine, the workpiece to be ground is placed flat (horizontally) with its central axis aligned vertically, and is attracted and held by a workpiece holder (magnetic chuck) with a circular cross section that is interposed between the workpiece and the output shaft of a rotary drive source that is coaxially arranged below it. The workpiece holder is connected to the output shaft by an appropriate means. With this configuration, the workpiece, workpiece holder, and output shaft rotate together around the central axis of the workpiece during grinding.

[0003] Since the grinding accuracy of a workpiece is greatly affected by the accuracy of the connection of the workpiece holder to the output shaft, the workpiece holder must be connected to the output shaft with high accuracy and strength. Furthermore, since the grinding accuracy of a workpiece is also affected by the accuracy of the workpiece being held (supported) by the workpiece holder, the workpiece holder is replaced depending on the shape and size of the workpiece to be held. Taking the above into consideration, the workpiece holder is generally detachably connected to the output shaft using bolts. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-320352 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as described above, when the workpiece holder is connected to the output shaft of the rotary drive source using a bolt, the work of removing and attaching (re-attaching) the bolt is time-consuming and labor-intensive to replace the workpiece holder, which results in a problem of extended downtime for the grinding machine.

[0006] In view of this situation, the present invention aims to provide a connecting mechanism that is interposed between a workpiece holding section that holds a workpiece with a circular cross section that is placed flat or upright so that it can rotate together with the workpiece, and an output shaft of a rotary drive source that is placed coaxially below the workpiece holding section, and that enables the workpiece holding section and the output shaft to be connected so that they can rotate together with the workpiece and can be easily replaced. [Means for solving the problem]

[0007] The present invention, which has been devised to achieve the above object, is a coupling mechanism that is interposed between a workpiece holding section that holds a workpiece having a circular cross section that is placed flat or vertically so as to be rotatable together with the workpiece, and an output shaft of a rotary drive source that is coaxially arranged below the workpiece holding section, and that couples the workpiece holding section and the output shaft so as to be rotatable together in a separable state, a connecting attachment that is fixed to the tip of the output shaft and holds a plurality of clampers that can be turned by a predetermined amount around a horizontal support shaft; As the clamper moves back and forth within its rotatable range, the pressure applying portion provided on the clamper moves between a retracted position where it does not come into contact with the work holding portion and a restraining position where it presses the work holding portion against the connecting attachment to restrain it.

[0008] According to the connecting mechanism having the above configuration, when the clamper with the pressure unit in the retracted position is rotated in one direction about the horizontal support shaft (horizontal axis) to place the pressure unit in the restraining position, the workpiece holder can be connected to the output shaft via the connecting attachment. On the other hand, when the clamper with the pressure unit in the restraining position is rotated in the other direction about the horizontal axis to place the pressure unit in the retracted position, the workpiece holder can be separated from the output shaft (the connecting attachment fixed thereto). In short, according to the connecting mechanism of the present invention, the workpiece holder can be attached to and detached from the output shaft simply by rotating the clamper (a predetermined amount) about the horizontal axis, so that the workpiece holder can be replaced quickly and easily without using special tools, etc.

[0009] Furthermore, the fixing force of the work holding part relative to the output shaft (or the connecting attachment fixed thereto) is determined by the pressing force applied to the work holding part by the pressure part of the clamper. This pressing force can be adjusted by the relative positional relationship between the pressure part positioned in the restraint position and the work holding part (the part to be pressed), and the biasing force of the elastic member described below, so that the required high fixing force can be appropriately secured.

[0010] In the above-mentioned connecting mechanism, the clampers can be provided at two locations facing each other in the radial direction with the workpiece holder in between. In this case, it is preferable to provide the connecting mechanism with a link mechanism that rotates one clamper in conjunction with (synchronized with) the rotation of the other clamper. This allows the replacement of the workpiece holder to be completed quickly.

[0011] In the above-described connecting mechanism, the clamper may be provided with a biasing member that biases the pressure part in a direction that presses the workpiece holder against the connecting attachment when the pressure part is in the restraining position, thereby firmly fixing the workpiece holder to the connecting attachment.

[0012] When the connecting mechanism according to the present invention is disposed below the workpiece holder that holds a workpiece in a flat position (and above the output shaft of the rotary drive source), the clamper can have an arm that extends radially outward below the pressure unit that is in the restraining position, and it is preferable that the center of gravity of the arm when the pressure unit is in the restraining position is located below the horizontal axis that serves as the center of rotation of the clamper. In this way, when centrifugal force acts on the clamper held by the connecting attachment that rotates integrally with the output shaft as the output shaft of the rotary drive source rotates, a force that presses the pressure unit against the workpiece holder can be generated. This increases the fixing force of the workpiece holder relative to the connecting attachment during rotation of the output shaft, enabling the workpiece to be precisely machined.

[0013] According to the connecting mechanism of the present invention described above, as mentioned above, the workpiece holding part can be easily connected to the output shaft for replacement, and therefore, if this connecting mechanism is used in a grinding machine, the time required for replacing the workpiece support part of the grinding machine will be reduced, resulting in excellent equipment operating rates. [Effects of the Invention]

[0014] As described above, the connecting mechanism according to the present invention allows the workpiece holding portion, which holds the workpiece having a circular cross section from below so that it can rotate integrally with the workpiece, to be easily and interchangeably connected to the output shaft of the rotary drive source. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1(a) is a plan view conceptually showing the state in which a grinding machine into which a connecting mechanism according to an embodiment of the present invention is incorporated is performing internal grinding, and FIG. 1(b) is a cross-sectional view taken along line AA in FIG. 1(a). [Figure 2] FIG. 1(a) is a schematic plan view showing a state in which a grinding machine into which a connecting mechanism according to an embodiment of the present invention is incorporated is performing peripheral grinding, and FIG. 1(b) is a cross-sectional view taken along line AA in FIG. 1(a). [Figure 3]FIG. 2 is an exploded perspective view of a workpiece rotating mechanism including a connecting mechanism according to an embodiment of the present invention. [Figure 4] 1 is a longitudinal cross-sectional view (axially parallel cross-sectional view) of a workpiece rotating mechanism including a connecting mechanism according to an embodiment of the present invention, showing a cross-sectional view when a pressure applying portion of a clamper is in a retracted position. [Figure 5] FIG. 2 is a longitudinal cross-sectional view of a workpiece rotating mechanism including a connecting mechanism according to an embodiment of the present invention, showing a state in which a pressure applying portion of a clamper is in a restraining position. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0017] The coupling mechanism according to an embodiment of the present invention is incorporated into a workpiece rotation mechanism that rotates the workpiece around its axis, for example, in a grinding machine that grinds the peripheral surface of a workpiece having a circular cross section. The "periphery of the workpiece" refers to both the inner and outer peripheral surfaces of the workpiece. Therefore, the coupling mechanism according to this embodiment can be used in both grinding machines that perform internal grinding (grinding the inner peripheral surface of the workpiece) and grinding machines that perform peripheral grinding (grinding the outer peripheral surface of the workpiece). An example of a workpiece having a circular cross section is a rolling bearing raceway (an annular base material that serves as a raceway). Below, an overview of a grinding machine that performs internal grinding is briefly described with reference to FIGS. 1(a) and 1(b), and an overview of a grinding machine that performs peripheral grinding is briefly described with reference to FIGS. 2(a) and 2(b). In the following description, the term "axial direction" refers to the direction along the central axis of the circular workpiece W, and the terms "radial direction" and "circumferential direction" refer to the radial and circumferential directions, respectively, of a circle centered on the central axis.

[0018] 1(a) and 1(b), which performs internal grinding, includes a grinding wheel 2 attached to the output shaft 3 of a rotary drive source and movable in the axial and radial directions of an annular workpiece W placed flat (horizontally positioned) with its central axis aligned vertically, a workpiece support device 4 that supports the outer circumferential surface of the workpiece W, and a workpiece rotation mechanism 5 that rotates the workpiece W around its central axis. In this grinding machine 1, the grinding wheel 2 is placed on the inner periphery of the workpiece W, and the outer grinding surface 2a of the grinding wheel 2, which is rotated in the opposite direction to the rotation of the workpiece W by the output shaft 3, is pressed against the inner circumferential surface Wa of the workpiece W, which is rotated by the workpiece rotation mechanism 5, thereby finishing the inner circumferential surface Wa of the workpiece W to a predetermined shape and precision.

[0019] Internal grinding performed by the grinding machine 1 is performed by pressing the outer grinding surface 2a of the grinding wheel 2, which rotates at a position eccentric to the workpiece W, against a portion of the inner peripheral surface Wa of the workpiece W. As a result, stress acts on the workpiece W during internal grinding, causing the workpiece W to move in the radial direction. The workpiece support device 4 contacts and supports the outer peripheral surface Wb of the workpiece W to prevent unintended movement of the workpiece W due to the stress acting on the workpiece W during internal grinding (and the rotational force of the grinding wheel 2, etc.). The workpiece support device 4 includes a shoe holder 7 that fixedly holds a shoe 6 disposed radially outside the workpiece W, and a base plate 8 to which the shoe holder 7 is attached. The outer peripheral surface Wb of the workpiece W is contact-supported by the shoe 6 held by the shoe holder 7. A plurality of shoes 6 (two in this example) are provided at intervals around the circumferential direction of the workpiece W. In this embodiment, the shoes 6 are provided at two locations that are 90° out of phase with each other in the circumferential direction. The workpiece rotating mechanism 5 is housed (placed) in a hole 8a provided in the base plate 8.

[0020] Next, the grinding machine 1 shown in FIGS. 2(a) and 2(b) for performing peripheral grinding differs from the grinding machine 1 shown in FIGS. 1(a) and 1(b) for performing internal grinding in the position of the grinding wheel 2 during grinding. That is, the grinding wheel 2 is positioned radially outward of the workpiece W, and the rotating peripheral grinding surface 2a is pressed against a portion of the outer peripheral surface Wb of the workpiece W to finish the outer peripheral surface Wb of the workpiece W to a predetermined shape and precision. The grinding machine 1 for performing peripheral grinding has substantially the same configuration as the grinding machine 1 for performing internal grinding, except for the position of the grinding wheel 2, which differs from that of the grinding machine 1 for performing internal grinding. Therefore, the components and parts of the grinding machine 1 shown in FIG. 2 are assigned the same reference numerals as those of the grinding machine 1 shown in FIG. 1, and redundant explanations will be omitted.

[0021] The workpiece rotation mechanism 5 including the coupling mechanism 9 according to an embodiment of the present invention will be described in detail below with reference to Figures 3 to 5. The workpiece rotation mechanism 5 includes a workpiece holding section 11 that is disposed below the workpiece W in a flat position and that holds the workpiece W so that the workpiece W can rotate integrally with the workpiece W, an output shaft 10 of a rotational drive source (a rotational drive source separate from the rotational drive source that rotationally drives the grinding wheel 2) that is disposed below the workpiece support section 11, and a coupling mechanism 9 that separably couples the workpiece holding section 11 and the output shaft 10 so that the workpiece can rotate integrally with the workpiece W.

[0022] The workpiece holding portion 11 is a bottomed tubular member having a cylindrical tubular portion 11a and a bottom portion 11b that closes the lower end opening of the tubular portion 11a. A downwardly protruding convex portion 11c is provided at the center of the lower end of the bottom portion 11b, and a flange 11d is provided on the outer periphery of the lower end of the bottom portion 11b. The workpiece holding portion 11 is, for example, formed of a magnetic material that holds the workpiece W rotatably integrally therewith by magnetic force (magnetic attraction force), and has a tubular portion 11a with a diameter and shape corresponding to the diameter and shape of the workpiece W to be held. Therefore, when the workpiece W to be held is changed to one with a different diameter, etc., the workpiece holding portion 11 is replaced with one having a diameter, etc. that matches the workpiece W to be held.

[0023] The connecting mechanism 9 includes a connecting attachment 12 interposed between the output shaft 10 and the workpiece holding portion 11, and a plurality of clampers 13 held by the connecting attachment 12. In this embodiment, the clampers 13 are provided at two locations facing each other in the radial direction across the workpiece holding portion 11 (connecting attachment 12).

[0024] The connecting attachment 12 has a protrusion 12a and a recess 12b at the center of its lower end and upper end, respectively. The protrusion 12a fits into a recess provided in the center of the upper end of the output shaft 10, and a protrusion 11c provided in the center of the lower end of the bottom 11b of the workpiece holding part 11 fits into the recess 12b. This allows the output shaft 10, the connecting attachment 12, and the workpiece holding part 11 to be coaxially arranged. After the protrusion 12a of the connecting attachment 12 is fitted into the recess of the output shaft 10, a flange 12c provided on the outer periphery of the lower end of the connecting attachment 12 is bolted to the output shaft 10 (see FIG. 3). This securely fixes the connecting attachment 12 to the output shaft 10.

[0025] The recessed / protruding fitting structure of the workpiece holding portion 11 and the connecting attachment 12 may differ from the illustrated example in that a protruding portion protruding upward may be provided in the center of the upper end of the connecting attachment 12, and a recess into which this protruding portion is fitted may be provided in the center of the lower end of the workpiece holding portion 11. Furthermore, the recessed / protruding fitting structure of the output shaft 10 and the connecting attachment 12 may differ from the illustrated example in that a protruding portion protruding upward may be provided in the center of the upper end of the output shaft 10, and a recess into which this protruding portion is fitted may be provided in the center of the lower end of the connecting attachment 12.

[0026] The clamper 13 includes a clamper body 14 , a pivot holder 15 , a pivot 16 , a spring guide 17 , a coil spring 18 as an “elastic member,” and a guide receiver 19 .

[0027] The clamper body 14 is generally U-shaped and includes a gripping portion 14a and an arm portion 14b that are arranged generally parallel to each other, and a connecting portion 14c that connects the inner diameter ends of the gripping portion 14a and the arm portion 14b. The gripping portion 14a is a portion that is gripped when operating the clamper 13. The arm portion 14b is located below the gripping portion 14a (closer to the output shaft 10) and is provided to increase the fixing force of the workpiece holding portion 11 to the connecting attachment 12 when the output shaft 10 rotates (during grinding processing) (details will be described later). A pressure portion 14d that applies pressure to the workpiece holding portion 11 is provided at the inner diameter end of the gripping portion 14a, and a support surface 14e that supports the flange 11d of the workpiece holding portion 11 from below is provided at the upper end of the connecting portion 14c.

[0028] The pivot holder 15 is fixed to the outer peripheral surface of the connecting attachment 12 and holds a pivot 16 as a "horizontal support shaft" inserted through a pivot insertion hole provided in the connection portion 14c of the clamper body 14. With this configuration, the clamper body 14 (clamper 13) is capable of pivoting a predetermined amount around the horizontal support shaft (pivot shaft 16). In this embodiment, the clamper body 14 is capable of pivoting within a range from a first tilted position (see FIG. 4) in which the outer diameter end of the gripping portion 14a (and arm portion 14b) is positioned below the inner diameter end of the gripping portion 14a to a second tilted position (see FIG. 5) in which the outer diameter end of the gripping portion 14a is positioned slightly above the inner diameter end of the gripping portion 14a. In the illustrated example, to change the posture of the clamper body 14 from the first inclined posture to the second inclined posture (or from the second inclined posture to the first inclined posture), the clamper 13 is rotated about the rotation axis 16 by approximately 15°.

[0029] The connecting mechanism 9 of this embodiment is provided with a link mechanism so that when one of the two clampers 13 (clamper main body 14) is rotated, the other clamper 13 can be rotated in conjunction with the other. The link mechanism of this embodiment includes a pair of linear links 20 arranged parallel to each other, and a connecting pin 21 that connects the linear links 20 and the connecting portion 14c of the clamper main body 14 so as to be rotatable relative to each other, and the linear links 20 are arranged in a groove portion 12d provided in the connecting attachment 12.

[0030] 4, when the two clampers 13 (clamper bodies 14) are in the first inclined position, the distance between the pressure members 14d is greater than the diameter of the flanges 11d of the workpiece holding portions 11, and the two pressure members 14d and the flanges 11d of the workpiece holding portions 11 are not in contact with each other in the radial direction. Therefore, when the clampers 13 are in the first inclined position, the pressure members 14d are in what is referred to as the "retracted position" in the present invention, and the workpiece holding portions 11 can be attached to or detached from the connecting mechanism 9 including the connecting attachment 12 without contacting (interfering with) the clampers 13. When the clampers 13 are in the first inclined position, the workpiece holding portions 11 are supported from below by the support surfaces 14e of the clamper bodies 14, and the outer bottom surfaces of the workpiece holding portions 11 and the opposing upper end surfaces of the connecting attachments 12 face each other with an axial gap between them.

[0031] 4, i.e., with the workpiece holding portion 11 supported from below by the support surface 14e of the clamper body 14, when the clamper 13 is rotated upward and the attitude of the clamper body 14 is changed from the first inclined attitude to the second inclined attitude, as shown in FIG. 5, the contact between the workpiece holding portion 11 and the support surface 14d of the clamper body 14 is released, while the pressure portion 14d of the clamper body 14 comes into contact with the flange 11d of the workpiece holding portion 11, pressing the workpiece holding portion 11 against the connecting attachment 12. This restrains the workpiece holding portion 11, restricting its movement relative to the connecting attachment 12. Therefore, when the clamper 13 (clamper body 14) is in the second inclined attitude shown in FIG. 5, the pressure portion 14d can be said to be in the "restraint position" as defined in the present invention.

[0032] As described above, in the connecting mechanism 9 of this embodiment, when the clamper 13, with the pressure portion 14d of the clamper body 14 located in the retracted position, is rotated in one direction about the pivot shaft 16 to position the pressure portion 14d at the restraining position, the workpiece holding portion 11 can be connected to the output shaft 10 via the connecting attachment 12. On the other hand, when the clamper 13, with the pressure portion 14d located in the restraining position, is rotated in the other direction about the pivot shaft 16 to position the pressure portion 14d at the retracted position, the workpiece holding portion 11 can be separated from the output shaft 10 (the connecting attachment 12 fixed thereto). In short, according to the connecting mechanism 9 of this embodiment, the workpiece holding portion 11 can be attached to and detached from the output shaft 10 simply by rotating the clamper 13 (by a predetermined amount) about the pivot shaft 16, so that the replacement of the workpiece holding portion 11 can be performed quickly and easily without using special tools or the like.

[0033] The guide receiver 19 is fixed to the outer circumferential surface of the connecting attachment 12 below the fixed portion of the swivel shaft holder 15, and one end of a spring guide 17 arranged along the longitudinal direction of the arm portion 14b of the clamper main body 14 is fitted into this guide receiver 19. The other end of the spring guide 17 is fitted and fixed to the inner diameter end of the arm portion 14b that constitutes the clamper main body 14, and a coil spring (compression coil spring) 18 as an elastic member attached to the outer periphery of the spring guide 17 is interposed between the clamper main body 14 and the connecting attachment 12 (or the guide receiver 19 fixed thereto) in a state where it is elastically compressed in its axial direction.

[0034] 4 and 5, the minimum separation distance between the guide receiver 19 and the clamper body 14 is greater when the pressure applying portion 14d of the clamper body 14 is in the restraining position than when the pressure applying portion 14d is in the retracted position. Therefore, when the pressure applying portion 14d of the clamper body 14 is in the restraining position, the coil spring 18 interposed between the guide receiver 19 and the clamper body 14 is elastically extended and deformed more than when the pressure applying portion 14d is in the retracted position. In addition, the clamper body 14 is provided with an arm portion 14b extending along the axial direction of the spring guide 17, and the other end of the spring guide 17 is fitted and fixed to the arm portion 14b. Therefore, when the pressure applying portion 14d is in the restraining position, the elastic restoring force of the coil spring 18 interposed between the guide receiver 19 and the clamper body 14 acts on the clamper body 14. This elastic restoring force acts as a biasing force that urges the pressure applying portion 14d of the clamper body 14 in the direction of pressing the work holding portion 11 (flange 11d) against the connecting attachment 12, thereby increasing the fixing force of the work holding portion 11 against the connecting attachment 12.

[0035] 5, the workpiece rotation mechanism 5 including the connecting mechanism 9 and rotating shaft 10 configured as described above rotates the workpiece W held by the workpiece holding part 11 around its central axis by being driven to rotate with the pressure section 14d of the clamper body 14 constituting the clamper 13 positioned in the restraining position. In this embodiment, by providing the coil spring 18 in the above-described manner in the clamper 13, the workpiece holding part 11 can be firmly fixed to the connecting attachment 12, and therefore to the output shaft 10 (so that they can rotate integrally).

[0036] In the connecting mechanism 9 of this embodiment, when the pressure applying portion 14d of the clamper body 14 is located in the restraining position and the output shaft 10 (including the workpiece rotating mechanism 5) is rotated, the center of gravity G of the arm portion 14b provided on the clamper body 14 is located below the pivot axis 16 of the clamper 13 (see FIG. 5). In this way, when centrifugal force acts on the clamper 13 held by the connecting attachment 12 that rotates integrally with the output shaft 10 as the output shaft 10 is rotated, a force can be generated that presses the pressure applying portion 14d against the flange 11d of the workpiece holding portion 11. This increases the fixing force of the workpiece holding portion 11 to the connecting attachment 12 while the output shaft 10 is rotating, allowing the workpiece W to be ground with high precision.

[0037] The coupling mechanism 9 according to one embodiment of the present invention and the workpiece rotating mechanism 5 including this coupling mechanism 9 have been described above, but the present invention is not limited to this embodiment.

[0038] For example, in the connecting mechanism 9 described above, the clampers 13 are arranged opposite each other at two locations in the circumferential direction, but the clampers 13 can also be arranged at three or more locations in the circumferential direction. However, if the clampers 13 are arranged at three or more locations in the circumferential direction, it becomes difficult to operate all of the clampers 13 in conjunction with each other (to provide a link mechanism that can operate all of the clampers 13 in conjunction with each other). Therefore, it is preferable to arrange the clampers 13 opposite each other at two locations in the circumferential direction.

[0039] Furthermore, the workpiece rotation mechanism 5 including the connecting mechanism 9 can be used not only to rotate the workpiece W placed flat with its central axis aligned vertically, but also to rotate the workpiece W placed vertically with its central axis aligned horizontally. In this case, the rotation axis of the workpiece rotation mechanism 5 is in a horizontal position.

[0040] Furthermore, the connecting mechanism 9 described above can be used not only for the work rotation mechanism 5 incorporated in the grinding machine 1, but also for connecting the output shaft of a rotary drive source to a work holding part that needs to be detachably connected to this output shaft. [Explanation of symbols]

[0041] 1 grinding machine 2 Grinding wheels 3 output shaft 4 Work support device 5 Work rotation mechanism 9 Connection mechanism 10 Output shaft 11 Work holding section 12 Connecting attachment 13 Clamper 14 Clamper body 14a Grip part 14b Arm section 14d Pressure section 14e Support surface 16 Swivel axis (horizontal support axis) 17 Spring guide 18 Coil spring (elastic member) G center of gravity

Claims

1. A coupling mechanism is interposed between a workpiece holding section that holds a workpiece having a circular cross section that is placed flat or vertically so as to be rotatable together with the workpiece, and an output shaft of a rotary drive source that is coaxially arranged with the workpiece holding section, and that couples the workpiece holding section and the output shaft so as to be rotatable together in a separable state, a connecting attachment that is fixed to the tip of the output shaft and holds a plurality of clampers that can be turned by a predetermined amount around a horizontal support shaft; A connecting mechanism characterized in that, as the clamper reciprocates within its rotatable range, a pressure member provided on the clamper transitions between a retracted position where it does not contact the workpiece holding portion and a restraining position where it presses the workpiece holding portion against the connecting attachment to restrain it.

2. The clampers are provided at two locations facing each other in the radial direction with the workpiece holding portion in between, 2. The connecting mechanism according to claim 1, further comprising a link mechanism that causes one of the clampers to pivot in conjunction with the other of the clampers as the other clamper pivots.

3. The connecting mechanism according to claim 1 , wherein the clamper includes an elastic member that biases the pressure portion in a direction that presses the workpiece holding portion against the connecting attachment when the pressure portion is positioned in the restraining position.

4. The workpiece holder is disposed below the workpiece holder that holds the workpiece in a flat position, 2. The coupling mechanism according to claim 1, wherein the clamper has an arm portion extending radially outward below the pressure applying portion positioned at the restraining position, and the center of gravity of the arm portion is positioned below the support shaft when the pressure applying portion is positioned at the restraining position.

5. A grinding machine equipped with the coupling mechanism according to any one of claims 1 to 4.

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