WO2024000775A1 - Workpiece clamping device and workpiece transfer method - Google Patents

Abstract

A workpiece clamping device, comprising an integrated frame (1) and at least two clamping fixtures (3), wherein the integrated frame comprises a mounting plate (11) and a cam turntable (12); the cam turntable is pivotally connected to the center of the mounting plate, and the cam turntable can at least rotate between a workpiece releasing position and a workpiece locking position; the clamping fixtures are movably connected to the integrated frame; and each clamping fixture has one end cooperating with the cam turntable and radially moving as the cam turntable rotates, so that the other end of the clamping fixture clamps or releases the workpiece. Also disclosed is a method for transferring a workpiece. The workpiece clamping device is suitable for clamping and transferring a large-aperture plane grating, can solve the problem of cumbersome and high-risk operation during a loading process in the existing method, can achieve quick loading, stable transfer, convenient operation and stable clamping without touching the surface of the grating, and can also achieve the fine adjustment and locking of clamping.

Description

Workpiece holding device and workpiece transfer method

Cross-references to related applications

This disclosure claims the priority of Chinese patent application CN202210744723.7 submitted on June 27, 2022. The entire content of the above application is incorporated herein by reference.

Technical field

The present disclosure relates to the technical field of tooling fixtures, and in particular to a workpiece clamping device and a workpiece transfer method, which are particularly suitable for clamping and transferring planar gratings.

Background technique

At present, laser interferometers and grating rulers can simultaneously meet the needs of displacement measurement systems with a range of hundreds of millimeters, sub-nanometer resolution, and nanometer precision. However, the principle of laser interferometer results in its long optical path, so the measurement accuracy and repeatability are greatly affected by the environment, and the stability is difficult to improve. In contrast, the grating scale measurement subsystem is not sensitive to environmental influences, and has the characteristics of high measurement accuracy and fast operation speed, which has been widely researched and developed.

The focus and difficulty in manufacturing flat grating rulers is the manufacturing and testing of gratings. The surface with microstructure on the flat grating substrate is used as the grating surface, and is used with the reading head to achieve the position measurement function; the smooth surface on the substrate is used as the bonding surface, and is used with the grating mounting plate to achieve high-precision assembly; the above two surfaces have the same surface shape and roughness etc. have extremely high requirements, and precision testing such as surface shape and grating pitch must be carried out before being put into use. The grating surface type test bench is a precision machine for surface type and grating pitch testing. When testing the surface type and grating pitch of a flat grating, it is necessary to transfer the flat grating from the grating storage tooling to the workpiece table of the surface type test bench. The grating surface is an extremely fragile structure and must be strictly protected from contact and contamination. If the grating surface is accidentally touched, it will have an unpredictable impact on the measurement system. Therefore, the safety of the grating transfer process must be strictly ensured. As shown in Figure 1, the grating surface occupies the main part, and only a few millimeters of space at the edge allow contact. This poses a big challenge to the transfer of planar gratings, and the transfer of planar gratings is a prerequisite for testing grating quality. Among the existing methods, one is to carry it directly without using tools, and the other is to use bolts to locate individual stuck points (see Figure 2). Both methods require multiple people to operate and their hands are in direct contact with the grating, making the operation cumbersome and highly dangerous.

Therefore, how to provide a tooling for planar grating transfer is an urgent problem that those skilled in the art need to solve.

Contents of the invention

The present disclosure provides a workpiece clamping device and a workpiece transfer method to solve at least one of the above technical problems. The above technical solution provided by the present disclosure is particularly suitable for clamping and transferring large-diameter planar gratings. It can overcome the problem of cumbersome and high-risk operations in the existing method during the installation process, and can quickly install the card without touching the surface of the grating. Steady transfer.

Specifically, one aspect of the present disclosure provides a workpiece clamping device, which includes an integrated frame and at least two clamping fixtures;

The integrated frame includes a mounting plate and a cam turntable, the cam turntable is pivotally connected to the center of the installation plate, and the cam turntable can at least rotate between a workpiece releasing position and a workpiece locking position;

The clamping fixture is movably connected to the integrated frame. One end of the clamping fixture cooperates with the cam turntable and moves in the radial direction with the rotation of the cam turntable, so that the other end of the clamping fixture is clamped or loosen said workpiece.

Optionally, the mounting plate is provided with a locking mechanism, and the cam turntable is provided with locking slots and releasing slots that cooperate with the locking mechanism.

Optionally, a guide assembly is provided near the edge of the installation plate. The guide assembly includes a fixing block fixed to the installation plate and a guide groove opened on the fixing block. The clamping fixture passes through located in the guide groove.

Optionally, the clamping fixture includes a connecting rod and a clamping bracket. One end of the connecting rod matches the cam turntable, the clamping bracket is fixedly connected to the other end of the connecting rod, and the clamp The shape of the tight bracket is adapted to the shape of the workpiece.

Optionally, the connecting rod is slidably matched with the fixed block of the guide assembly provided on the edge of the mounting plate, the connecting rod is passed through the guide groove opened on the fixed block, and the connecting rod is in contact with the fixed block of the guide assembly. A limiting structure is provided between the guide grooves, and the limiting structure is used to prevent the connecting rod from escaping from the guide groove in a direction other than its own sliding direction.

Optionally, the end of the connecting rod that matches the cam turntable is provided with a fitting piece, the fitting piece has a sliding fitting part or a rolling fitting part, a limiting groove is provided on the cam dial, and the sliding fitting part or The rolling fitting part fits in the limiting groove.

Optionally, a clamping block is provided on the clamping bracket. The clamping block includes a connecting plate, an adjustment plate and a gasket. The connecting plate is fixed on the clamping bracket, and the connecting plate is connected to the clamping bracket. The adjustment plates are connected through three adjustment screws, and the gaskets are fixedly connected to the adjustment plates.

Optionally, the gasket is provided with a slot for engaging the edge of the workpiece, or the gasket is provided with a protrusion capable of supporting the lower surface of the edge of the workpiece.

Optionally, the mounting plate is further provided with a handle and a hollow groove, and the cam turntable is provided with a push rod for rotating the cam turntable, and the push rod is limited to the hollow area of the hollow groove.

Another aspect of the present disclosure provides a workpiece transfer method using any one of the workpiece clamping devices described above. The workpiece transfer method includes the following steps:

Rotate the cam turntable to the workpiece release position, and move the workpiece clamping device above the workpiece;

Move the workpiece clamping device downward so that the clamping portion of the clamping fixture corresponds to the clamping position around the workpiece;

Rotate the cam turntable to the workpiece locking position so that the clamping portion of the clamping fixture moves toward the center of the clamping device to clamp the workpiece;

Move the workpiece clamping device above the designated position where the workpiece is to be transferred;

The cam turntable is reversely rotated to cause the clamping portion of the clamping fixture to move reversely and release the workpiece to place the workpiece at the designated position.

Compared with the prior art, the advantages of the present disclosure are:

The workpiece clamping solution provided by the present disclosure can avoid contact, is easy to operate, has stable clamping, and can realize fine-tuning and locking functions of clamping. details as follows:

1. The gaskets in the clamping bracket or clamping block are designed to be suitable for the shape of the workpiece and made of non-metallic materials. In addition, the transfer operation process is designed to achieve manual control of the grating workpiece during the entire transfer operation. Zero contact. In this way, only the gasket contacts the edge of the grating during the clamping process, achieving zero contact between the clamping device and the grating surface; the chemical properties of the part of the material that contacts the grating are stable and will not cause contamination to the edge of the grating; the clamping is performed through the mounting plate and the adjustment plate Fine-adjust the holding angle and distance to make the clamping stable and firm. The above design ensures safety during grating transfer;

2. The clamping motion in the X and Y directions is converted into a rotational motion in the Rz direction through the cam turntable, which simplifies the single operation process; through the adjustment of the clamping fixture layout and the fine adjustment of the clamping block during the first clamping, it can be realized Repeated and precise clamping simplifies repeated operations;

3. The tooling adopts a modular design, and by changing the layout of the clamping fixture and replacing the clamping bracket and clamping block, gratings of different shapes can be clamped;

4. A wear-resistant layer with low friction resistance and high rigidity is used to separate the slide rail assembly and the sliding rod to improve the stability of the clamping;

5. The locking function of the cam turntable and the mounting plate is realized through the locking mechanism to improve the safety during the circulation process.

Description of drawings

The present disclosure will be described in more detail below based on embodiments and with reference to the accompanying drawings.

Figure 1 is a schematic structural diagram of a planar grating in the prior art;

Figure 2 is a schematic structural diagram of a clamping tool for a planar grating in the prior art;

Figure 3 is a schematic structural diagram of a workpiece clamping device (with a planar grating clamped) in an embodiment of the present disclosure;

Figure 4 is a top view of a workpiece clamping device (with a planar grating clamped) in one embodiment of the present disclosure;

Figure 5 is a schematic structural diagram of the clamping fixture and guide assembly part in one embodiment of the present disclosure;

Figure 6 is a schematic diagram of the connecting rod in the clamping fixture in Figure 5 cooperating with the guide assembly;

Figure 7 is an illustration of a variation of the workpiece clamping device in one embodiment of the present disclosure;

Figure 8 is a schematic structural diagram of the clamping block in one embodiment of the present disclosure;

Figure 9 is a schematic diagram of the connection structure between the cam rotary disk and the cam rod in one embodiment of the present disclosure.

The reference numbers in the figure are:

1-Integrated frame; 11-Mounting plate; 111-Hollow groove; 12-Cam turntable; 121-Limiting groove; 2-Guide component; 3-Clamping fixture; 31-Connecting rod; 32-Clamping bracket; 33 -Clamping block; 331-connecting plate; 332-adjusting plate; 333-gasket; 4-push rod; 5-locking mechanism; 6-first handle; 7-second handle.

Detailed ways

The present disclosure will be further described below in conjunction with the accompanying drawings.

Referring to the workpiece clamping device shown in Figures 3-4, one embodiment of the present disclosure provides a workpiece clamping device. The workpiece clamping device can be installed on other automated equipment, and of course can also be manually operated. The workpiece clamping device is mainly composed of two parts: an integrated frame 1 and a clamping fixture 3. The integrated frame 1 mainly plays the role of support and rotation, and the clamping fixture 3 implements the execution component of the workpiece clamping. It can be two parts. One or more than two, for example, the clamping cards in Figure 3 have four, evenly distributed on the integrated frame 1 along the circumferential direction.

Specifically, the integrated frame 1 includes a mounting plate 11 and a cam turntable 12. The cam turntable 12 is pivotally connected to the center of the installation plate 11. The cam turntable 12 can at least rotate between a workpiece releasing position and a workpiece locking position. The workpiece is loosened. The open position and workpiece locking position can be marked on the mounting plate 11 or on the cam turntable 12 through holes and other structures. As shown in Figure 3-4, according to the number of clamping fixtures 3, the cam turntable is provided with four cam structures that can realize the cam trajectory. The cam structure can be the outermost boundary line or the inside of the turntable. A gradual limiting groove 121 is formed, which uses a cam-like movement trajectory to drive the clamping fixture 3 during the rotation process, so that the clamping fixture 3 performs actions such as swinging or linear movement.

The clamping fixture 3 is movably connected to the integrated frame 1. One end of the clamping fixture 3 cooperates with the cam turntable 12 and moves in the radial direction with the rotation of the cam turntable 12, so that the other end of the clamping fixture 3 clamps or releases the workpiece.

In one or some preferred embodiments, the mounting plate 11 is provided with a locking mechanism 5 , and the cam turntable 12 is provided with locking slots and releasing slots that cooperate with the locking mechanism 5 . Equivalently, the locking mechanism 5 can also be provided on the cam turntable 12, and the mounting plate 11 is provided with loosening slots and locking slots that cooperate with the locking mechanism 5 in the loosening position and the locking position respectively. The locking mechanism 5 includes a spring pin inside. After twisting the external handle, the spring pin is lifted upward and disengaged from the slot, so that the cam turntable 12 can rotate relative to the mounting plate 11 .

As shown in Figure 5-7, a guide assembly 2 is provided near the edge of the installation plate 11. The guide assembly 2 includes a fixed block fixed to the installation plate 11 and a guide groove opened on the fixed block. The clamping fixture 3 is inserted through in the guide groove. Especially as can be seen from Figures 5 and 6, the clamping fixture 3 is inserted into the groove body of the guide assembly 2. This groove body is the guide groove on the fixed block and is used to move the clamping fixture 3. Perform limit guidance.

The clamping fixture 3 includes a connecting rod 31 and a clamping bracket 32. One end of the connecting rod 31 matches the cam turntable 12, the clamping bracket 32 is fixedly connected to the other end of the connecting rod 31, and the shape of the clamping bracket 32 matches the shape of the workpiece. adapt. The length of the connecting rod 31 can be adjusted according to the size of the workpiece, and forms a sliding pair with the guide assembly 2 .

Figure 7(1)-(4) shows four forms of clamping brackets. Of course, the actual production is designed according to the shape of the workpiece and is not limited to the structure shown in Figure 7.

In one embodiment, the connecting rod 31 is slidably matched with the fixed block of the guide assembly 2 provided on the edge of the mounting plate 11. The connecting rod 31 is passed through the guide groove opened on the fixed block, and is provided between the connecting rod 31 and the guide groove. The limiting structure is used to prevent the connecting rod 31 from escaping from the guide groove in a direction other than its own sliding direction.

Specifically, as shown in Figures 5 and 6 of the accompanying drawings, the connecting rod 31 of the clamping bracket is inserted into the guide groove on the fixed block of the guide assembly 2, and the connecting rod 31 can slide along its own length direction relative to the guide groove. , a limiting structure is provided between the connecting rod 31 and the guide groove. The limiting structure is used to limit the degree of freedom of the connecting rod 31 in other directions (except for sliding relative to the guide groove along its own length direction), which can prevent the connecting rod 31 from sliding. Exit the guide groove in the other direction.

There are many specific forms of the limiting structure. For example, it can be realized by the size of the connecting rod 31 and the guide groove. For example, in the structure shown in Figure 6 of the accompanying drawings, the guide groove notch is partially narrowed, so that the connecting rod 31 cannot Come out of the guide groove. Or the guide groove is directly processed into a channel structure that penetrates the inside of the fixed block, and the connecting rod 31 directly penetrates the guide groove. This also ensures that the connecting rod 31 cannot come out of the guide groove from other directions.

In some embodiments, a fitting piece is provided at the end of the connecting rod 31 that matches the cam turntable 12. The fitting piece has a sliding fitting part or a rolling fitting part. The cam turntable 12 is provided with a limiting groove 121, and the sliding fitting part or the rolling fitting part fits In the limiting groove 121, the limiting groove 121 has a certain limiting effect on the fitting parts, thereby enhancing the reliability of the structure, and the limiting groove and the fitting parts are in contact and matched through the fitting part, which can be based on the sliding fitting part. Sliding contact or rolling contact with smaller friction based on rolling mating parts can also be used. Referring to Figures 4 and 9, a vertically upward screw is provided on the end 312 of the cam rod as a fitting part, and a bearing or a bushing is set on the screw as a rolling fitting part. The bearing or bushing is preferably an oil-free bearing or a bushing. Oil-free bushing to avoid contamination of the workpiece. Correspondingly, the cam turntable 12 is provided with a limiting groove 121 , and the limiting groove 121 may extend along a straight line as a whole, or may be an arc-shaped groove extending along an arc as shown in FIG. 9 .

The limiting groove 121 extends entirely along the circumferential direction of the cam turntable 12, and along its extension direction, the relative position of the limiting groove 121 in the radial direction of the cam turntable 12 (relative to the rotation center of the cam turntable 12) constantly changes, so that the bearing or The sleeve is arranged in the limiting groove 121 and is in rolling contact with the groove wall of the limiting groove 121, so that the cam turntable 12 can cooperate with the clamping fixture 3 and drive the clamping fixture 3 when the cam turntable 12 rotates.

In some embodiments, as shown in FIG. 8 , in order to facilitate adjustment, a clamping block 33 is provided on the clamping bracket 32 . The clamping block 33 includes a connecting plate 331 , an adjusting plate 332 and a gasket 333 . The connecting plate 331 is fixed On the clamping bracket 32, the connecting plate 331 and the adjusting plate 332 are connected through three adjusting screws, and the adjusting plate 332 is fixedly connected with a gasket 333.

Preferably, the above-mentioned adjusting screw can be movably connected to the connecting plate 331, and the angle of the connection can be fine-adjusted, and is fixed by the top screw on the top of the connecting plate 331, thereby realizing the three-degree-of-freedom fine-tuning and locking functions based on the three-point support principle. The adjustment method is: after completing the workpiece clamping action, loosen the three locking screws on the clamping block 33, adjust the corresponding three jackscrews, so that the clamping block gasket 333 is close to the edge of the workpiece, and lock after adjusting in place. Tighten the locking screw; after the adjustment is completed, push open the locking mechanism 5 of the locking cam turntable 12 and lock it again until you feel a slight resistance.

Among them, the gasket 333 is made of special non-metallic material to avoid scratching the grating surface during operation. The shape of the gasket is specially designed to ensure that it does not contact the grating surface during the clamping process, ensuring the safety of clamping.

Further, referring to (1)-(4) in Figure 8, the gasket 333 is provided with a slot for engaging the edge of the workpiece (8(3) in the figure), or the gasket 333 is provided with a groove that can support the workpiece. The protruding portion on the lower surface of the edge ((1), (2), (4) in Figure 8), the protruding portion can be a cylindrical or polygonal structure, and is not specifically limited.

In one embodiment, the mounting plate 11 is provided with a handle and a hollow groove 111 , and the cam turntable 12 is provided with a push rod 4 corresponding to the hollow groove 111 for rotating the cam turntable 12 , and the push rod 4 is limited to the hollow groove 111 within the hollow area. The arrangement of the hollow groove 111 provides a certain range of movement space for the push rod 4, making the setting and movement of the push rod 4 more convenient and reducing the weight of the mounting plate 11. The push rod 4 is used to manually drive the cam turntable 12 to rotate.

Specifically, the handle includes a first handle 6 and a second handle 7. The first handle 6 is installed in the middle of the mounting plate 11, and the second handle 7 is installed on both sides of the mounting plate 11 through matching screws to facilitate transportation and subsequent operations.

To sum up, the above-mentioned workpiece clamping device converts the clamping or loosening movement of the clamping fixture 3 in the X and Y directions into the rotational movement of the cam turntable 12 in the Rz direction (rotation in the plane where the X and Y directions are located), It simplifies the operation process, reduces the uncertainty caused by cumbersome operations, improves the safety of the operation, and can quickly install and transfer the card without touching the grating surface. It is easy to operate, has stable clamping, and can realize clamping. Supports fine-tuning and locking functions.

Another embodiment of the present disclosure also provides a workpiece transfer method, which is implemented using the workpiece clamping device in any of the above embodiments. The workpiece transfer method includes the following steps:

Rotate the cam turntable to the workpiece release position and move the workpiece clamping device above the workpiece;

Move the workpiece clamping device downward so that the clamping part of the clamping fixture corresponds to the clamping position around the workpiece;

Rotate the cam turntable to the workpiece locking position, causing the clamping part of the clamping fixture to move toward the center of the clamping device to clamp the workpiece;

Move the workpiece clamping device above the designated position where the workpiece is to be transferred;

Rotate the cam turntable in the reverse direction, causing the clamping part of the clamping fixture to move in the opposite direction and release the workpiece to place the workpiece at the designated position.

In the above method steps, with reference to the structure of the clamping device shown in Figures 2 to 9 of the accompanying drawings, it should be noted that: 1. Expansion operation of the clamping device: loosen the locking mechanism 5, push the push rod 4 to reverse the cam turntable 12 As the hour hand rotates, the bearing (rolling fitting part) of the connecting rod 31 rolls along the inner wall of the limiting groove 121 of the cam turntable 12 and realizes the expansion movement of the four clamping fixtures. When the cam turntable 12 rotates counterclockwise at a specific angle, the locking mechanism 5 is locked again to keep the workpiece clamping device in an expanded state.

2. Tool clamping operation: hold the push rod 4, loosen the locking mechanism 5, relax the push rod 4 to rotate the cam turntable 12 clockwise, and the bearing (rolling fit part) of the connecting rod 31 along the limit groove 121 of the cam turntable 12 The inner wall rolls in reverse direction to realize the clamping movement of the four clamping fixtures. When the cam turntable 12 rotates clockwise at a specific angle, the locking mechanism 5 is locked again to keep the flat grating clamping device in a clamped state.

In the description of the present disclosure, it should be noted that, unless otherwise clearly stated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. Connection, or integral connection; it can be a mechanical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium; it can be an internal connection between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this disclosure can be understood on a case-by-case basis.

In the disclosed description, furthermore, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. . Thus, features defined as "first", "second", and "third" may explicitly or implicitly include one or more of these features.

While the present disclosure has been described with reference to preferred embodiments, various modifications may be made and equivalents may be substituted for components thereof without departing from the scope of the disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any way. The present disclosure is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims (10)

1. A workpiece clamping device, characterized in that the workpiece clamping device includes an integrated frame and at least two clamping fixtures;

   The integrated frame includes a mounting plate and a cam turntable, the cam turntable is pivotally connected to the center of the installation plate, and the cam turntable can at least rotate between a workpiece releasing position and a workpiece locking position;

   The clamping fixture is movably connected to the integrated frame. One end of the clamping fixture cooperates with the cam turntable and moves in the radial direction with the rotation of the cam turntable, so that the other end of the clamping fixture is clamped or loosen said workpiece.
2. The workpiece clamping device according to claim 1, wherein the mounting plate is provided with a locking mechanism, and the cam turntable is provided with locking slots and loosening slots that cooperate with the locking mechanism.
3. The workpiece clamping device according to claim 1, wherein a guide assembly is provided near the edge of the mounting plate, and the guide assembly includes a fixing block fixed to the mounting plate and an opening in the fixing block. There is a guide groove on the guide groove, and the clamping fixture is inserted into the guide groove.
4. The workpiece clamping device according to claim 1, wherein the clamping fixture includes a connecting rod and a clamping bracket, one end of the connecting rod cooperates with the cam turntable, and the clamping bracket is fixedly connected to The other end of the connecting rod, and the shape of the clamping bracket is adapted to the shape of the workpiece.
5. The workpiece clamping device according to claim 4, characterized in that the connecting rod is slidably matched with the fixed block of the guide assembly provided on the edge of the mounting plate, and the connecting rod is penetrated through the fixed block. There is a guide groove on the connecting rod, and a limiting structure is provided between the connecting rod and the guide groove. The limiting structure is used to prevent the connecting rod from escaping from the guide groove in a direction other than its own sliding direction.
6. The workpiece clamping device according to claim 4, characterized in that, the end of the connecting rod that matches the cam turntable is provided with a fitting piece, the fitting piece has a sliding fitting part or a rolling fitting part, and the cam dial A limiting groove is provided on the upper body, and the sliding fitting part or the rolling fitting part fits in the limiting groove.
7. The workpiece clamping device according to any one of claims 4 to 6, characterized in that a clamping block is provided on the clamping bracket, and the clamping block includes a connecting plate, an adjustment plate and a gasket. The connecting plate is fixed on the clamping bracket, the connecting plate and the adjusting plate are connected through three adjusting screws, and the gasket is fixedly connected to the adjusting plate.
8. The workpiece clamping device according to claim 7, wherein the gasket is provided with a slot for engaging the edge of the workpiece, or the gasket is provided with a slot capable of being supported under the edge of the workpiece. The ridges on the surface.
9. The workpiece clamping device according to any one of claims 1 to 4, characterized in that the mounting plate is further provided with a handle and a hollow groove, and the cam turntable is provided with a push rod for rotating the cam turntable. , the push rod is limited to the hollow area of the hollow groove.
10. A workpiece transfer method using the workpiece clamping device according to any one of claims 1 to 9, characterized in that the workpiece transfer method includes the following steps:

    Rotate the cam turntable to the workpiece release position, and move the workpiece clamping device above the workpiece;

    Move the workpiece clamping device downward so that the clamping portion of the clamping fixture corresponds to the clamping position around the workpiece;

    Rotate the cam turntable to the workpiece locking position so that the clamping portion of the clamping fixture moves toward the center of the clamping device to clamp the workpiece;

    Move the workpiece clamping device above the designated position where the workpiece is to be transferred;

    The cam turntable is reversely rotated to cause the clamping portion of the clamping fixture to move reversely and release the workpiece to place the workpiece at the designated position.

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