Fine positioning worktable for large workpieces

Abstract

The present application relates to a kind of large workpiece fine positioning workbench, effectively solve the problem of large workpiece fine positioning difficulty;Solving technical solutions include base, positioning unit and several support units, the axis of base is vertically positioned hole, positioning hole is in the basis of round hole, on the inner wall of round hole, process multiple circumferentially distributed arc grooves, positioning unit includes lower structure and a conical disc, lower structure is placed in positioning hole, the side of lower structure is equipped with multiple wedge blocks, wedge block and the arc groove of positioning hole are matched to complete circumferential and horizontal positioning;The present application is through the excess of positioning unit, greatly reduce the difficulty of large workpiece fine positioning, and can realize circumferential automatic positioning.

Description

Technical Field

[0001] This invention relates to the field of positioning worktables, specifically a fine-tuning positioning worktable for large workpieces. Background Technology

[0002] When machining disc-shaped parts such as large gears, large bushings, and large washers, alignment with the worktable is required to determine the machining datum. Coarse alignment is performed during workpiece hoisting, followed by fine-tuning and precise positioning using a jacking mechanism. For example, the invention patent with application number CN201910390938.1 uses multiple self-aligning bolts to push the workpiece horizontally to achieve alignment with the work platform. However, for large workpieces, due to their large structure and mass, fine-tuning and positioning is very difficult. There are also automatic centering devices, such as those shown in invention patent application number CN202110822144.5, which use a three-jaw chuck or other mechanisms with automatic centering functions to automatically position the workpiece. However, for workpieces that have not undergone finishing, the dimensional accuracy is poor, making it difficult to achieve ideal positioning results using automatic centering mechanisms. Moreover, such automatic centering mechanisms cannot perform circumferential automatic positioning; therefore, fine-tuning positioning cannot be replaced by automatic centering mechanisms. Summary of the Invention

[0003] To address the difficulty of fine-tuning and positioning large workpieces, this invention provides a fine-tuning and positioning worktable for large workpieces.

[0004] The technical solution includes a base, a positioning unit and several support units. The base is disc-shaped, and the support units are evenly distributed around the upper surface of the base. Each support unit includes a first piston hole opened on the base, a first piston installed in the first piston hole, a second piston hole opened at the upper end of the first piston, a second piston installed in the second piston hole, and multiple balls evenly distributed around the upper end of the first piston. A vertical positioning hole is formed at the axis of the base. This positioning hole is created by machining multiple evenly distributed arc-shaped grooves on the inner wall of a circular hole. The extension direction of the arc-shaped grooves is parallel to the axis of the circular hole. The positioning unit includes a lower structure and a conical disk. The lower structure is placed inside the positioning hole. The lower structure includes a circular upper positioning plate and a circular lower positioning plate. Several oblique grooves are formed on the lower surface of the upper positioning plate and the upper surface of the lower positioning plate. The oblique grooves on the upper and lower positioning plates correspond one-to-one, forming an "eight" shape with the larger end facing outwards. The positioning unit also includes several wedge blocks, the number of slots is equal to the number of wedge blocks, and the number of arc grooves is equal to the number of wedge blocks. The wedge blocks are clamped in the slots one by one. The upper and lower sides of the wedge blocks are inclined surfaces that fit with the bottom of the inclined grooves. The outer ends of the wedge blocks extend out of the slots. A vertical rod is coaxially mounted on the upper surface of the upper positioning plate. The conical disk is slidably mounted on the vertical rod with its small end facing down. A first clamping nut located above the conical disk is screwed on the vertical rod. A pressure cap located above the conical disk is passed through the vertical rod. A second clamping nut located above the pressure cap is screwed on the vertical rod.

[0005] The lower positioning plate has a third piston hole, and a third piston is installed in the third piston hole. The upper end of the third piston is fixedly connected to the upper positioning plate.

[0006] The lower end of the first piston is provided with a first limiting step, and the opening of the first piston hole is equipped with a first limiting sleeve.

[0007] The lower end of the second piston is provided with a second limiting step, and the opening of the second piston hole is equipped with a second limiting sleeve.

[0008] The lower end of the first piston is provided with an oil pipe that communicates with the bottom of the second piston hole. The lower end of the oil pipe passes through the bottom of the first piston hole and exits the base downwards. The oil pipe and the base are in a sliding seal fit. Hydraulic oil enters and exits the second piston hole through the oil pipe.

[0009] The lower structure also includes a ring located between the upper positioning plate and the lower positioning plate. The outer wall of the ring is evenly distributed with radial rods of the same number as the wedge blocks. Each wedge block has a mounting hole on its outer end face. The radial rods pass through the mounting holes from the inner end of the wedge blocks one by one. A compression spring is installed between the outer end of the radial rod and the bottom of the mounting hole.

[0010] The vertical rod and the upper positioning plate are screwed together.

[0011] The diameter of the outer end face of the wedge block is less than or equal to the diameter of the arc surface of the arc groove.

[0012] This invention greatly reduces the difficulty of fine-tuning the positioning of large workpieces by using a transition of positioning units, and can also achieve automatic positioning in the circumferential direction. Attached Figure Description

[0013] Figure 1 This is an assembly diagram of the present invention.

[0014] Figure 2 This is an exploded view of the present invention.

[0015] Figure 3 This is a front sectional view of the first state of the present invention.

[0016] Figure 4 This is a front sectional view of state two of the present invention.

[0017] Figure 5 This is a front sectional view of state three of the present invention.

[0018] Figure 6 This is a front sectional view of state four of the present invention.

[0019] Figure 7 for Figure 2 Sectional view along the AA direction.

[0020] Figure 8 for Figure 3 A magnified view of position B in the middle.

[0021] Figure 9 This is a three-dimensional view of the base.

[0022] Figure 10 This is a 3D view of the upper positioning plate.

[0023] Figure 11 This is a 3D view of the lower positioning plate.

[0024] Figure 12 This is a 3D view of the wedge-shaped block.

[0025] Figure 13 This is an assembly drawing of the lower structure of the positioning unit.

[0026] Figure 14 This is an exploded view of the lower structure of the positioning unit. Detailed Implementation

[0027] Referring to the accompanying drawings, the present invention includes a base 1, a positioning unit, and several support units. The base 1 is disc-shaped, and the support units are evenly distributed around the upper surface of the base 1. Each set of support units includes a first piston hole 2 opened on the base 1, a first piston 3 installed in the first piston hole 2, a second piston hole 4 opened at the upper end of the first piston 3, a second piston 5 installed in the second piston hole 4, and multiple balls 6 evenly distributed around the upper end of the first piston 3. The first piston 3 can be pushed upward out of the base 1, and the second piston 5 can be pushed upward out of the first piston 3. When the second piston 5 is in the pushed-out state, the workpiece is supported by multiple second pistons 5. After the second piston 5 retracts into the second piston hole 4, the workpiece is supported by the balls 6 on the top of the first piston 3. At this time, the workpiece can move horizontally under the action of a small force. After the first piston 3 retracts into the first piston hole 2, the workpiece is placed on the upper surface of the base 1. A vertical positioning hole 7 is formed at the axis of the base 1. The positioning hole 7 is formed by machining multiple evenly distributed arc-shaped grooves on the inner wall of the circular hole. The extension direction of the arc-shaped grooves is parallel to the axis of the circular hole. The positioning unit includes a lower structure and a conical disk 8. The lower structure is placed in the positioning hole 7 and cooperates with the positioning hole 7 for positioning. The lower structure includes a circular upper positioning plate 9 and a circular lower positioning plate 10. The upper positioning plate 9 and the lower positioning plate 10 are coaxially connected by a hydraulic mechanism and the axial distance can be adjusted by the hydraulic mechanism. Several inclined grooves 11 are formed on the lower surface of the upper positioning plate 9 and the upper surface of the lower positioning plate 10. The two inclined grooves 11 correspond one-to-one, forming an "eight"-shaped groove with the larger end facing outward. The positioning unit also includes several wedge blocks 12. The number of grooves is equal to the number of wedge blocks 12, which is equal to the number of arc grooves. The wedge blocks 12 are clamped in the grooves one-to-one. The upper and lower sides of the wedge blocks 12 are inclined surfaces that fit against the bottom of the inclined grooves 11. The outer ends of the wedge blocks 12 extend out of the grooves. When the axial distance between the upper positioning plate 9 and the lower positioning plate 10 decreases, the wedge blocks 12 will be squeezed outward under the action of the inclined surfaces. As the wedge blocks 12 extend outward, they will automatically abut against the lowest point of the arc grooves one-to-one, completing the alignment of the positioning unit with the positioning hole 7 and the circumferential alignment. A vertical rod 13 is coaxially mounted on the upper end face of the upper positioning plate 9. A conical disc 8, with its small end facing downwards, slides coaxially through the vertical rod 13. A first clamping nut 14, located above the conical disc 8, is screwed onto the vertical rod 13. The vertical rod 13 passes through the inner hole of the workpiece, and the upper end face of the upper positioning plate 9 contacts the lower end face of the workpiece. The conical disc 8 passes through the upper end of the vertical rod 13, and its lower end extends into the inner hole of the workpiece. During the tightening of the first clamping nut 14, the positioning unit automatically adjusts to be coaxial with the workpiece under the action of the conical surface of the conical disc 8. The vertical rod 13 is fitted with a pressure cap 15 located above the conical disc 8. A second clamping nut 16 located above the pressure cap 15 is screwed onto the vertical rod 13. After the conical disc 8 is positioned, the pressure cap 15 is installed and the second clamping nut 16 is tightened. The lower end of the pressure cap 15 is pressed against the upper end face of the workpiece. The positioning unit and the workpiece are mainly fixed by the pressure of the pressure cap 15 and the upper positioning plate 9. The pressure of the conical disc 8 mainly plays a guiding and positioning role, which is to avoid excessive pressure damaging the conical surface of the conical disc 8 and the upper opening of the inner hole of the workpiece.

[0028] The lower positioning plate 10 has a third piston hole 17, and a third piston 18 is installed in the third piston hole 17. The upper end of the third piston 18 is fixedly connected to the upper positioning plate 9. The third piston 18 can move in both directions. The third piston 18 can pull the upper positioning plate 9 and the lower positioning plate 10 to move axially relative to each other, thereby adjusting the axial distance between the upper positioning plate 9 and the lower positioning plate 10.

[0029] The lower end of the first piston 3 is provided with a first limiting step 19, and the opening of the first piston hole 2 is equipped with a first limiting sleeve 20. The first limiting sleeve 20 is screwed on and can position the extension height of the first piston 3 so that all the first pistons 3 have the same extension limit height.

[0030] The lower end of the second piston 5 is provided with a second limiting step 21, and the opening of the second piston hole 4 is equipped with a second limiting sleeve 22. The second limiting sleeve 22 is screwed on and can limit the extension height of the second piston 5 so that all the second pistons 5 have the same extension limit height.

[0031] The lower end of the first piston 3 is provided with an oil pipe 23 that communicates with the bottom of the second piston hole 4. The lower end of the oil pipe 23 passes through the bottom of the first piston hole 2 and exits the base 1. The oil pipe 23 and the base 1 are in a sliding seal fit. Hydraulic oil enters and exits the second piston hole 4 through the oil pipe 23.

[0032] The lower structure also includes a ring 24 located between the upper positioning plate 9 and the lower positioning plate 10. The outer circumference of the ring 24 is evenly distributed with radial rods 25, the same number as the wedge blocks 12. Each wedge block 12 has a mounting hole 26 on its outer end face. The radial rods 25 are inserted into the mounting holes 26 from the inner end of the wedge block 12. A compression spring 27 is installed between the outer end of the radial rod 25 and the bottom of the mounting hole 26. A nut is screwed onto the outer end of the radial rod 25 as a support point for the outer end of the compression spring 27. The compression spring 27 applies an inward force along the radial rod 25 to the wedge block 12 to prevent the wedge block 12 from falling off and to keep the wedge block 12 in contact with the inclined groove 11.

[0033] The vertical rod 13 is screwed onto the upper positioning plate 9. The vertical rod 13 is installed after the workpiece is hoisted, so it is not necessary to hoist the workpiece too high.

[0034] The diameter of the outer end face of the wedge block 12 is less than or equal to the diameter of the arc surface of the arc groove, so that the outer end of the wedge block 12 can maintain good contact with the arc groove and slide smoothly in the arc groove.

[0035] The positioning process of this invention consists of the following steps and states: Step 1: Push both the first piston 3 and the second piston 5 to their limit. At this point, the upper end of the first piston 3 is higher than the base 1, and the upper end of the second piston 5 is higher than the ball bearing 6 at the upper end of the first piston 3. The lower structure of the positioning unit is located inside the positioning hole 7, and the wedge block 12 does not contact the inner wall of the positioning hole 7, allowing the lower structure to move freely within the positioning hole 7. Place the workpiece on the base 1. When placing it, roughly adjust the position of the workpiece with the goal of concentricity between the workpiece and the base 1. After the workpiece is placed on the base 1, it is supported by several second pistons 5. After placement, screw the vertical rod 13 through the inner hole of the workpiece onto the upper positioning plate 9, and then turn the small end of the conical disk 8 towards the top. The tapered disc 8 is pressed against the upper opening of the workpiece's inner hole by tightening the first clamping nut 14 onto the vertical rod 13. During the clamping process, the positioning unit will automatically move to be concentric with the workpiece under the guidance of the tapered surface of the tapered disc 8. If the workpiece has circumferential positioning requirements, before fully tightening the first clamping nut 14, rotate the positioning unit to align the circumferential positioning reference on the positioning unit with the circumferential positioning reference on the workpiece. Then fully tighten the first clamping nut 14, install the pressure cap 15, and tighten the second clamping nut 16. The workpiece and the positioning unit are clamped and fixed by the pressure cap 15 and the upper positioning plate 9. This is state one. Figure 3 As shown; If the inner hole accuracy of the workpiece can meet the positioning requirements for mating with the conical disk 8, then the positioning unit does not need to be fine-tuned after the conical disk 8 is automatically positioned. If the inner hole accuracy of the workpiece cannot meet the positioning requirements for mating with the conical disk 8, after the conical disk 8 has completed its initial automatic positioning, it is necessary to check the alignment accuracy between the workpiece and the positioning unit, and completely loosen the first locking nut, slightly loosen the second locking nut so that the positioning unit can be moved under force, then fine-tune the position of the positioning unit, and finally completely tighten the second locking nut, while the first locking nut does not need to be tightened. In order to loosen and tighten the first locking nut without removing the pressure cap 15, the side wall of the pressure cap 15 is processed into a hollow shape. Alternatively, instead of using the conical disc 8 for initial positioning, the positioning unit can be finely adjusted for positioning, and then the pressure cap 15 and the second locking nut can be used to tighten and fix it.

[0036] Step Two: The second piston 5 is lowered and retracted into the second piston hole 4. The workpiece descends synchronously with the second piston 5, and finally lands on the first piston 3, supported by the ball bearings 6 on the first piston 3; this is state two. Figure 4 As shown.

[0037] Step 3: The third piston 18 pulls the upper positioning plate 9 and the lower positioning plate 10 closer together. During this process, the wedge block 12 is pushed outward by the inclined surface of the groove 11. When the wedge block 12 contacts the inner wall of the positioning hole 7, further pushing outward will cause the wedge block 12 to move towards the lowest point of the arc groove. This will cause the positioning unit to rotate circumferentially. Since all the wedge blocks 12 are pushed out at the same distance, the positioning unit and the workpiece will also be horizontally pushed and adjusted during the pushing out of the wedge block 12. When the wedge block 12 completely abuts the bottom of the arc groove, the positioning unit automatically completes the centering and circumferential positioning with the positioning hole 7, i.e., the base 1. That is, the workpiece and the base 1 are aligned and circumferentially positioned. The ball bearing 6 supports the workpiece so that it can move under the pushing force of the wedge block 12. This is state three. Figure 5 As shown.

[0038] Step 4: The first piston 3 descends and fully retracts into the first piston hole 2. The workpiece and positioning unit descend synchronously with the first piston 3, and finally the workpiece lands on the base 1, where it is supported. The workpiece is then positioned with the base 1. This is state four. Figure 6 As shown.

[0039] When positioning large workpieces, this invention eliminates the need for precise positioning by directly micro-moving the workpiece. Instead, it achieves positioning and fixation between the workpiece and the positioning unit, and then automatically positions the positioning unit (workpiece) and base 1 through the cooperation of the wedge block 12 and the positioning hole 7. Since the structure and mass of the positioning unit are much smaller than those of the workpiece and base 1, it has excellent adjustment flexibility and can easily perform fine-tuning positioning with the workpiece. Both the wedge block 12 and the positioning hole 7 are precision-machined positioning components, enabling high-precision automatic positioning. Therefore, the transition of the positioning unit greatly reduces the difficulty of fine-tuning positioning of large workpieces. Moreover, by moving the wedge block 12 towards the bottom of the arc-shaped groove, automatic circumferential positioning can be achieved.

Claims

1. A fine-tuning and positioning worktable for large workpieces, comprising a base (1), a positioning unit, and several support units, wherein the base (1) is disc-shaped, and the support units are evenly distributed around the circumference of the upper surface of the base (1), characterized in that, Each support unit includes a first piston hole (2) opened on the base (1), the first piston hole (2) is equipped with a first piston (3), the upper end of the first piston (3) is opened with a second piston hole (4), the second piston hole (4) is equipped with a second piston (5), and multiple balls (6) are evenly distributed around the upper end of the first piston (3). A vertical positioning hole (7) is opened at the axis of the base (1). The positioning hole (7) is formed by machining multiple circumferentially distributed arc-shaped grooves on the inner wall of the circular hole based on the circular hole. The extension direction of the arc-shaped grooves is parallel to the axis of the circular hole. The positioning unit includes a lower structure and a conical disk (8). The lower structure is placed in the positioning hole (7). The lower structure includes a circular upper positioning plate (9) and a circular lower positioning plate (10). Several inclined grooves (11) are opened on the lower surface of the upper positioning plate (9) and the upper surface of the lower positioning plate (10). The inclined grooves (11) on the upper positioning plate (9) and the lower positioning plate (10) correspond one-to-one. The upper and lower inclined grooves (11) form an "eight" shaped groove with the larger end facing outward. The positioning unit also includes several The number of slots of the dry wedge (12) is equal to the number of arc grooves. The wedge (12) is clamped in the slot one by one. The upper and lower sides of the wedge (12) are inclined surfaces that fit with the bottom of the inclined groove (11). The outer end of the wedge (12) extends out of the slot. A vertical rod (13) is coaxially installed on the upper end face of the upper positioning plate (9). The small end of the conical disk (8) slides coaxially through the vertical rod (13). A first clamping nut (14) located above the conical disk (8) is screwed on the vertical rod (13). A pressure cap (15) located above the conical disk (8) is passed through the vertical rod (13). A second clamping nut (16) located above the pressure cap (15) is screwed on the vertical rod (13).

2. The large workpiece fine-tuning and positioning worktable according to claim 1, characterized in that, The lower positioning plate (10) has a third piston hole (17), and a third piston (18) is installed in the third piston hole (17). The upper end of the third piston (18) is fixedly connected to the upper positioning plate (9).

3. The large workpiece fine-tuning and positioning worktable according to claim 1, characterized in that, The lower end of the first piston (3) is provided with a first limiting step (19), and the opening of the first piston hole (2) is equipped with a first limiting sleeve (20).

4. A large workpiece fine-tuning and positioning worktable according to claim 3, characterized in that, The lower end of the second piston (5) is provided with a second limiting step (21), and the opening of the second piston hole (4) is equipped with a second limiting sleeve (22).

5. A large workpiece fine-tuning and positioning worktable according to claim 3 or 4, characterized in that, The lower end of the first piston (3) is provided with an oil pipe (23) that communicates with the bottom of the second piston hole (4). The lower end of the oil pipe (23) passes through the bottom of the first piston hole (2) and exits the base (1). The oil pipe (23) and the base (1) are in sliding seal fit. Hydraulic oil enters and exits the second piston hole (4) through the oil pipe (23).

6. A large workpiece fine-tuning and positioning worktable according to claim 1, characterized in that, The lower structure also includes a ring (24) located between the upper positioning plate (9) and the lower positioning plate (10). The outer circumference of the ring (24) is evenly distributed with radial rods (25) in the same number as the wedge blocks (12). Each wedge block (12) has a mounting hole (26) on its outer end face. The radial rods (25) are inserted into the mounting holes (26) from the inner end of the wedge block (12) in a one-to-one correspondence. A compression spring (27) is installed between the outer end of the radial rod (25) and the bottom of the mounting hole (26).

7. A large workpiece fine-tuning and positioning worktable according to claim 1, characterized in that, The vertical rod (13) is screwed onto the upper positioning plate (9) by thread.

8. A large workpiece fine-tuning and positioning worktable according to claim 1, characterized in that, The outer end face of the wedge block (12) has a diameter less than or equal to the diameter of the arc groove.

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