Casting device for precise instrument part production

Abstract

The invention relates to the field of part casting, in particular to a casting device for precise instrument part production, which comprises a base, a lower die fixedly connected to the top of the base, rodless cylinders symmetrically arranged on the top of the base, an upper die slidably connected between the rodless cylinders, a cylinder arranged inside the upper die, and an injection pipe communicated with the upper die. And a moving-out frame is slidably connected to the rear portion in the lower mold and fixedly connected with the column body, a first threaded rod is rotatably connected to the top of the upper mold, and the first threaded rod is in threaded connection with the moving-out frame. Through cooperation of a first threaded rod, a worm, a worm gear and other components, a moving-out frame and a column body drive a bearing pedestal to be pulled out downwards, then an electric air cylinder controls a pushing frame to move forwards, and a pushing plate pushes the bearing pedestal forwards to fall off so as to facilitate collection; when the pushing frame moves forwards, under the cooperation of the first wedge-shaped block and the second wedge-shaped block, the pushing-out plate can be pulled to move backwards to reset when the pushing frame moves backwards.

Description

TECHNICAL FIELD

[0001] The application relates to the field of part casting, in particular to a casting device for precision instrument part production. BACKGROUND

[0002] At present, a bearing seat casting device for precision instrument part mainly comprises a mold assembly, a pouring system, a temperature control module and a support rack.

[0003] The basic working process is as follows: according to the structure parameters of the bearing seat, a corresponding sand mold or metal mold is designed, the alloy material in a molten state is injected into the mold cavity through the pouring system, and the bearing seat blank is formed after gradient cooling and solidification realized by the temperature control module. In this process, the demolding process is a key link connecting casting and subsequent processing, and the solidified bearing seat blank needs to be separated from the mold to be subjected to subsequent polishing, finishing and other treatments. The current mainstream bearing seat casting device generally adopts a manual demolding mode, that is, after the casting is cooled to a set temperature, an operator directly pries out or knocks off the casting from the mold cavity by means of a crowbar, a hammer and other tools.

[0004] The demolding mode has the disadvantages of complicated operation process, high labor intensity and low demolding efficiency, and therefore, the present application provides a casting device for precision instrument part production to overcome the above-mentioned disadvantages. SUMMARY

[0005] The technical scheme of the present application is as follows: a casting device for precision instrument part production, comprising a base, a lower mold fixedly connected to the top of the base, a pair of symmetrical rodless cylinders arranged on the top of the base, an upper mold slidably connected between the rodless cylinders, a column arranged in the upper mold, an injection pipe communicated with the upper mold, a removal frame slidably connected to the rear part of the lower mold, the removal frame being fixedly connected to the column, a first threaded rod rotatably connected to the top of the upper mold, and the first threaded rod being threadedly connected to the removal frame.

[0006] Further, a worm is rotatably connected to the rear upper part of the upper mold, a worm wheel is engaged with the front part of the worm, the worm wheel is fixedly connected to the first threaded rod, a first gear is fixedly connected to the side of the worm away from the worm wheel, a first rack is fixedly connected to the upper part of the base, and the first rack is engaged with the first gear.

[0007] Further, a push-out plate is arranged in the removal frame, a through hole is formed in the middle of the push-out plate, the push-out plate is sleeved on the outside of the column, and a metal ring is arranged in the front part of the through hole of the push-out plate.

[0008] Furthermore, it also includes an electric cylinder, which is located at the upper rear of the base. The front end of the telescopic rod of the electric cylinder is fixedly connected to a push frame. A symmetrically arranged square slot is opened at the rear of the push frame. A symmetrically arranged first wedge block is connected to the push plate near the square slot. The first wedge block and the push plate are slidably connected. A second wedge block is slidably connected to the push frame away from the electric cylinder. The second wedge block and the first wedge block cooperate. A first spring is connected between the second wedge block and the push frame.

[0009] Furthermore, it also includes a second spring, which is connected between the first wedge block and the push plate. The second wedge block is provided with a first triangular inclined block, and the side wall of the square groove is provided with symmetrically arranged second triangular inclined blocks.

[0010] Furthermore, it also includes a hollow round tube, which is set at the through hole position of the ejector plate. The hollow round tube is located behind the metal ring. An injection channel is opened on the side of the ejector plate near the square groove. The injection channel is connected to the hollow round tube. An arc-shaped support frame is fixedly connected to the inner circle of the hollow round tube. The arc-shaped support frame is fixedly connected to the ejector plate. A liquid outlet pipe is connected to the inner side of the hollow round tube along the circumferential direction. The liquid outlet pipe is fixedly connected to the arc-shaped support frame. An inlet pipe is set inside the pusher frame. The inlet pipe passes through the pusher frame. The liquid outlet of the inlet pipe is located at the front end of the pusher frame. The liquid inlet of the inlet pipe is located at the rear end of the pusher frame.

[0011] Furthermore, it also includes a perforated rotating ring, which is rotatably connected to the arc-shaped support frame. A cotton ring is bonded to the inner ring of the perforated rotating ring. A large gear ring is fixedly connected to the perforated rotating ring. The large gear ring meshes with the second gear. The second gear is fixedly connected to the second threaded rod. The second threaded rod is threadedly connected to the removal frame. The second threaded rod is rotatably connected to the push plate.

[0012] Furthermore, it also includes a crossbar frame, which is slidably connected inside the liquid outlet pipe. A conical plug is fixedly connected to the end of the crossbar frame. A third spring is connected between the crossbar frame and the liquid outlet pipe. A wedge frame is slidably connected to the ejector plate near the large gear ring. The wedge frame and the crossbar frame are in a pressing fit. The wedge frame and the pusher frame are in a pressing fit. A fourth spring is connected between the wedge frame and the ejector plate.

[0013] The beneficial effects are: 1. The present invention uses the cooperation of components such as the first threaded rod, worm, and worm wheel to make the removal frame and the column pull the bearing seat downward. Then, the electric cylinder controls the push frame to move forward, so that the push plate pushes the bearing seat forward for collection.

[0014] 2. When the pusher moves forward, the present invention, through the cooperation between the first wedge block and the second wedge block, enables the pusher to move backward and reset when it moves backward.

[0015] 3. The present invention connects the liquid inlet pipe and the injection channel, so that the release agent is injected into the hollow round tube. Then, when the ejector plate moves, the cotton ring rotates under the cooperation of the second threaded rod, the large gear ring and the second gear to evenly apply the release agent to the column body, so as to demold the bearing seat. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0017] Figure 2 This is a partial three-dimensional structural cross-sectional view of the present invention.

[0018] Figure 3 This is a three-dimensional structural diagram of the components of the present invention, including the second triangular wedge, the hollow circle, and the metal ring.

[0019] Figure 4 This is a three-dimensional structural diagram of the components of the present invention, including the second wedge block, the first spring, and the first triangular inclined block.

[0020] Figure 5 For the present invention Figure 4 A schematic diagram of the three-dimensional structure at point A in the middle.

[0021] Figure 6 This is a three-dimensional structural diagram of the components of the present invention, including the arc-shaped support frame, the wedge-shaped frame, and the fourth spring.

[0022] Figure 7 This is a three-dimensional structural diagram of the crossbar frame, the third spring, and the wedge frame of the present invention.

[0023] In the attached diagram, the following are the reference numerals: 1-base, 2-lower mold, 3-upper mold, 4-rodless cylinder, 5-injection pipe, 6-cylinder, 7-removal frame, 8-first threaded rod, 9-worm gear, 10-worm wheel, 11-first gear, 12-first rack, 13-ejection plate, 14-metal ring, 15-electric cylinder, 16-push frame, 17-square groove, 18-first wedge block, 19-second wedge block, 20-first spring. 21-Second spring, 22-First triangular wedge block, 23-Second triangular wedge block, 24-Hollow round tube, 25-Injection channel, 26-Arc-shaped support frame, 27-Outlet pipe, 28-Inlet pipe, 29-Perforated rotating ring, 30-Cotton ring, 31-Large gear ring, 32-Second gear, 33-Second threaded rod, 34-Conical plug, 35-Crossbar frame, 36-Third spring, 37-Wedge frame, 38-Fourth spring. Detailed Implementation

[0024] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0025] A casting apparatus for producing precision instrument parts, such as Figure 1As shown, it includes a base 1, a lower mold 2 fixedly connected to the top of the base 1, and rodless cylinders 4 symmetrically arranged on the top of the base 1. An upper mold 3 is slidably connected between the rodless cylinders 4. A column 6 is set inside the upper mold 3. An injection pipe 5 is connected to the upper mold 3. After the rodless cylinders 4 control the upper mold 3 to descend and the lower mold 2 to close, the molten alloy material is injected into the mold cavity between the upper mold 3 and the lower mold 2 through the injection pipe 5 for casting.

[0026] After the bearing housing has cooled and solidified, it needs to be demolded. The upper mold 3 is moved upwards by the rodless cylinder 4, which in turn moves the column 6 upwards. The column 6 pulls the bearing housing upwards, separating it from the lower mold 2. However, if the bearing housing needs to be demolded from the upper mold 3, it requires manual labor using tools such as pry bars and hammers to pry or knock the casting directly out of the mold cavity, which is cumbersome. Therefore, this embodiment provides the following solution:

[0027] like Figures 1-2 As shown, a removal frame 7 is slidably connected to the rear of the lower mold 2, and the removal frame 7 is fixedly connected to the column 6. A first threaded rod 8 is rotatably connected to the top of the upper mold 3, and the first threaded rod 8 is threadedly connected to the removal frame 7. A worm 9 is rotatably connected to the upper rear of the upper mold 3, and a worm wheel 10 is meshed at the front of the worm 9. The worm wheel 10 is fixedly connected to the first threaded rod 8. A first gear 11 is fixedly connected to the side of the worm 9 away from the worm wheel 10. A first rack 12 is fixedly connected to the upper part of the base 1, and the first rack 12 meshes with the first gear 11.

[0028] When the upper mold 3 moves upward, it causes the ejector frame 7, worm 9, worm wheel 10, and first gear 11 to move upward. When the first gear 11 meshes with the first rack 12, it causes the first gear 11 to rotate. The rotation of the first gear 11 causes the worm 9 to rotate, which in turn causes the worm wheel 10 to rotate. The rotation of the worm wheel 10 causes the first threaded rod 8 to rotate, which in turn causes the ejector frame 7 to move out from under the upper mold 3. This causes the column 6 to move downward, which in turn causes the bearing seat to move out of the upper mold 3. Afterward, the bearing seat needs to be manually removed from the column 6. Therefore, the following components are provided:

[0029] like Figure 3As shown, a push-out plate 13 is provided inside the removal frame 7. A through hole is opened in the middle of the push-out plate 13, and the diameter of the through hole is larger than the diameter of the column 6. The push-out plate 13 is sleeved on the outside of the column 6. A metal ring 14 is provided at the front of the through hole of the push-out plate 13. The metal ring 14 is in close contact with the column 6. The metal ring 14 can block the gap between the push-out plate 13 and the column 6, and can also prevent molten material from penetrating to the rear of the push-out plate 13 through the gap. Initially, the push-out plate 13 is located inside the removal frame 7, which can prevent the setting of the push-out plate 13 from affecting the forming of the bearing seat. When the bearing seat needs to be pushed out, the push-out plate 13 can be driven forward by a thrust. The push-out plate 13 drives the metal ring 14 forward together, so as to push the bearing seat forward for collection.

[0030] like Figure 1 and Figure 4 As shown, the driving force comes from the following sources: an electric cylinder 15 is installed at the upper rear of the base 1, and a pusher frame 16 is fixedly connected to the front end of the telescopic rod of the electric cylinder 15. A symmetrically arranged square groove 17 is opened at the rear of the ejector frame 7. After the column 6 drives the bearing seat to move out of the upper mold 3, the square groove 17 is at the front end of the ejector frame. Then, the pusher frame 16 can be moved forward by the extension of the telescopic rod of the electric cylinder 15. After the front end of the pusher frame 16 contacts the rear of the pusher plate, it will push the pusher plate forward, thus providing a pushing force to the pusher plate.

[0031] Next, the push plate needs to be pushed backward to reset. However, the push frame 16 and the push plate are only in contact and not connected. Therefore, when the electric cylinder 15 controls the push frame 16 to move backward to reset, the push plate cannot move backward to reset as well. Therefore, a pulling component is provided to pull the push plate to reset, as follows:

[0032] like Figures 3-5 As shown, the ejector plate 13 has a first wedge block 18 symmetrically arranged on the side near the square groove 17, and the pusher frame 16 is slidably connected to a second wedge block 19 on the side away from the electric cylinder 15. The second wedge block 19 and the first wedge block 18 cooperate, and a first spring 20 is connected between the second wedge block 19 and the pusher frame 16.

[0033] The pusher 16 moves forward, causing the second wedge block 19 to move forward. When the second wedge block 19 moves forward and contacts the wedge surface of the first wedge block 18, it will push the second wedge block 19 to move closer to each other. The first spring 20 is compressed. After the second wedge block 19 moves to the front of the first wedge block 18, the first spring 20 will drive the second wedge block 19 to move away from each other to reset. At this time, the flat surface of the second wedge block 19 is against the flat surface of the first wedge block 18. Then, when the pusher 16 moves backward, it will drive the second wedge block 19 to move backward to reset. At this time, the second wedge block 19 will push the first wedge block 18 to move backward. The first wedge block 18 will drive the push plate 13 and the metal ring 14 to move backward to reset. In this way, the effect of automatically pulling the push plate to reset can be achieved.

[0034] After the ejector plate 13 moves and resets, the pusher 16 continues to move backward away from the square groove 17. However, the first wedge block 18 abuts against the second wedge block 19, which prevents the pusher 16 from moving away from the square groove 17. Therefore, the first wedge block 18 and the pusher plate are made to slide together. A second spring 21 is connected between the first wedge block 18 and the pusher plate. The second wedge is provided with a first triangular inclined block 22, and the side wall of the square groove 17 is provided with symmetrically arranged second triangular inclined blocks 23.

[0035] After the ejector plate 13 moves back to its reset position, the pusher 16 continues to move back, causing the second wedge block 19 to move back. At this time, the second wedge block 19 will cause the first wedge block 18 to move back, the second spring 21 is compressed, and the ejector plate 13 remains stationary. When the second wedge block 19 moves back, it will cause the first triangular wedge block 22 to move. After the inclined surfaces of the first triangular wedge block 22 and the second triangular wedge block 23 come into contact, the first triangular wedge block 22 will move towards the side closer to each other, the first spring 20 will be compressed, and the first triangular wedge block 22 will cause the second wedge block 19 to move towards the side closer to each other and separate from the first wedge block 18. After that, the ejector continues to move, causing the second wedge block 19 and the first triangular wedge block 22 to move back. After the first triangular wedge block 22 and the second triangular wedge block 23 separate, under the action of the first spring 20, the second wedge block 19 and the first triangular wedge block 22 will move back to their reset positions.

[0036] During the process of the push plate moving forward to push out the bearing housing, the bearing housing may stick to the column 6, making demolding difficult. Therefore, as follows: Figure 6 As shown, a hollow circular tube 24 is provided at the through hole position of the ejector plate 13. The hollow circular tube 24 is located behind the metal ring 14. An injection channel 25 is opened on the side of the ejector plate 13 near the square groove 17. The injection channel 25 is connected to the hollow circular tube 24. An arc-shaped support frame 26 is fixedly connected to the inner circle of the hollow circular tube 24. The arc-shaped support frame 26 is fixedly connected to the ejector plate 13. The inner side of the hollow circular tube 24 is connected to the liquid outlet pipe 27 along the circumferential direction. The liquid outlet pipe 27 is fixedly connected to the arc-shaped support frame 26.

[0037] The release agent is injected into the hollow tube 24 through the injection channel 25 and then sprayed out onto the outer wall of the column 6 through the outlet pipe 27. In this way, the release agent can be automatically applied to the hollow tube 24 during the process of the ejector plate 13 pushing out the bearing seat, so that the bearing seat can be easily pushed out in the next manufacturing of the bearing seat.

[0038] Furthermore, an inlet pipe 28 is installed inside the push frame 16, which passes through the push frame 16. The outlet of the inlet pipe 28 is located at the front end of the ejector frame, and the inlet of the inlet pipe 28 is located at the rear end of the ejector frame. After the push frame 16 moves forward and inserts into the square groove 17, the outlet of the inlet pipe 28 is inserted into the injection channel 25. Thus, the injection channel 25 and the inlet pipe 28 are connected, and the inlet of the inlet pipe 28 is connected to an external injection device. The external injection device provides power to the release agent, injecting the release agent into the hollow round tube 24 for application of the release agent.

[0039] If the release agent is sprayed directly onto the column 6 through the outlet pipe 27, the release agent may flow along the bottom of the column 6 due to its fluidity. This would prevent the release agent from being evenly coated on the outside of the column 6, affecting subsequent demolding. Therefore, the following solution is proposed:

[0040] like Figure 6 As shown, a perforated rotating ring 29 is rotatably connected to the arc-shaped support frame 26. A cotton ring 30 is bonded to the inner ring of the perforated rotating ring 29. The release agent flows into the cotton ring 30 from the liquid inlet pipe 28, allowing the release agent to penetrate the cotton ring 30. When the push plate moves, the cotton ring 30 moves from the outer wall of the column 6. The perforated rotating ring 29 drives the cotton ring 30 to rotate through the drive component. The cotton ring 30 moves and rotates at the same time, which facilitates the even application of the release agent on the column 6.

[0041] The drive assembly includes a large gear ring 31, which is fixedly connected to a perforated rotating ring 29. The large gear ring 31 meshes with a second gear 32, which is fixedly connected to a second threaded rod 33. The second threaded rod 33 is threadedly connected to the removal frame 7 and rotatably connected to the push plate.

[0042] When the push plate moves, it drives the second threaded rod 33 to rotate. The rotation of the second threaded rod 33 drives the second gear 32 to rotate. The second gear 32 drives the large gear ring 31 to rotate. The rotation of the large gear ring 31 drives the perforated rotating ring 29 and the cotton ring 30 to rotate and apply the coating agent.

[0043] When the release agent is injected from the top and bottom of the hollow tube 24, the tube cannot be filled immediately. The release agent will flow directly out from the nearby outlet tube 27. This means that the release agent can only penetrate to a local area of ​​the cotton ring 30, which cannot achieve uniform seepage of the cotton ring 30 or uniform application of the release agent. Therefore, the following solution is set:

[0044] like Figures 6-7 As shown, a crossbar 35 is slidably connected inside the liquid outlet pipe 27. A conical plug 34 is fixedly connected to the end of the crossbar 35. A third spring 36 is connected between the crossbar 35 and the liquid outlet pipe 27. A wedge 37 is slidably connected to the push plate 13 near the large gear ring 31. The wedge 37 and the crossbar 35 are in a pressing fit. The wedge 37 and the push frame 16 are in a pressing fit. A fourth spring 38 is connected between the wedge 37 and the push plate 13.

[0045] Initially, the conical plug 34 blocks the outlet pipe 27, allowing the release agent to be injected into the hollow tube 24, completely filling it. This prevents the release agent from flowing unevenly out of the outlet pipe 27. Subsequently, when the front end of the pusher 16 moves forward and contacts the wedge-shaped frame 37, it will squeeze the wedge-shaped frame 37. At this time, because the push plate 13 is resisted by the gravity of the bearing seat, the push plate will not be displaced due to the pusher 16 squeezing the wedge-shaped frame 37. Therefore, the wedge-shaped frame 37 will move forward first, and the fourth spring 38 is... The wedge frame 37 compresses the crossbar frame 35, causing the crossbar frame 35 to pull outward. The third spring 36 is compressed, and the crossbar frame 35 moves the conical plug 34 to open the liquid outlet pipe 27. At this time, the release agent will evenly penetrate into the cotton ring 30. Then, the pusher frame 16 continues to move forward, which will push the ejector plate 13 forward to eject the bearing seat. Afterward, when the pusher frame 16 moves backward, the wedge frame 37 is released. Under the action of the fourth spring 38, the wedge frame 37 returns to its original position and releases the crossbar frame 35. The third spring 36 then drives the crossbar frame 35 and the conical plug 34 to return to their original positions.

[0046] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, all equivalent changes made to the content described in the claims of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A casting apparatus for producing precision instrument parts, comprising a base (1), a lower mold (2) fixedly connected to the top of the base (1), rodless cylinders (4) symmetrically arranged on the top of the base (1), an upper mold (3) slidably connected between the rodless cylinders (4), a column (6) disposed inside the upper mold (3), and an injection pipe (5) connected to the upper mold (3), characterized in that: The lower mold (2) has a sliding connection to the rear of the ejector frame (7), which is fixedly connected to the column (6). The upper mold (3) has a rotating connection to the top of the first threaded rod (8), which is threadedly connected to the ejector frame (7).

2. The casting apparatus for producing precision instrument parts as described in claim 1, characterized in that: It also includes a worm (9), which is rotatably connected to the upper part of the upper mold (3). A worm wheel (10) is meshed at the front of the worm (9). The worm wheel (10) is fixedly connected to the first threaded rod (8). A first gear (11) is fixedly connected to the side of the worm (9) away from the worm wheel (10). A first rack (12) is fixedly connected to the upper part of the base (1). The first rack (12) and the first gear (11) mesh.

3. The casting apparatus for producing precision instrument parts as described in claim 2, characterized in that: It also includes a push plate (13), which is set inside the removal frame (7). A through hole is opened in the middle of the push plate (13). The push plate (13) is sleeved on the outside of the column (6). A metal ring (14) is set in front of the through hole of the push plate (13).

4. The casting apparatus for producing precision instrument parts as described in claim 3, characterized in that: It also includes an electric cylinder (15), which is located at the upper rear of the base (1). The front end of the telescopic rod of the electric cylinder (15) is fixedly connected to a pusher frame (16). A square groove (17) is symmetrically arranged at the rear of the ejector frame (7). A first wedge block (18) is symmetrically arranged and connected to the side of the ejector plate (13) near the square groove (17). The first wedge block (18) and the pusher plate are slidably connected. A second wedge block (19) is slidably connected to the side of the pusher frame (16) away from the electric cylinder (15). The second wedge block (19) and the first wedge block (18) cooperate. A first spring (20) is connected between the second wedge block (19) and the pusher frame (16).

5. The casting apparatus for producing precision instrument parts as described in claim 4, characterized in that: It also includes a second spring (21), which is connected between the first wedge block (18) and the push plate. The second wedge is provided with a first triangular inclined block (22), and the side wall of the square groove (17) is provided with a symmetrically arranged second triangular inclined block (23).

6. The casting apparatus for producing precision instrument parts as described in claim 5, characterized in that: It also includes a hollow round tube (24), which is set at the through hole of the ejector plate (13). The hollow round tube (24) is located behind the metal ring (14). An injection channel (25) is opened on the side of the ejector plate (13) near the square groove (17). The injection channel (25) is connected to the hollow round tube (24). An arc-shaped support frame (26) is fixedly connected to the inner circle of the hollow round tube (24). The arc-shaped support frame (26) is fixedly connected to the ejector plate (13). The inner side of the hollow round tube (24) is connected to the liquid outlet pipe (27) along the circumferential direction. The liquid outlet pipe (27) is fixedly connected to the arc-shaped support frame (26). An inlet pipe (28) is set inside the pusher frame (16). The inlet pipe (28) passes through the pusher frame (16). The outlet of the inlet pipe (28) is located at the front end of the ejector frame. The inlet of the inlet pipe (28) is located at the rear end of the ejector frame.

7. A casting apparatus for producing precision instrument parts as described in claim 6, characterized in that: It also includes a perforated rotating ring (29), which is rotatably connected to the arc-shaped support frame (26). The inner ring of the perforated rotating ring (29) is bonded with a cotton ring (30). A large gear ring (31) is fixedly connected to the perforated rotating ring (29). The large gear ring (31) meshes with the second gear (32). The second gear (32) is fixedly connected to the second threaded rod (33). The second threaded rod (33) is threadedly connected to the removal frame (7). The second threaded rod (33) is rotatably connected to the push plate.

8. A casting apparatus for producing precision instrument parts as described in claim 7, characterized in that: It also includes a crossbar frame (35), which is slidably connected inside the liquid outlet pipe (27). A conical plug (34) is fixedly connected to the end of the crossbar frame (35). A third spring (36) is connected between the crossbar frame (35) and the liquid outlet pipe (27). A wedge frame (37) is slidably connected to the side of the push plate (13) near the large gear ring (31). The wedge frame (37) and the crossbar frame (35) are in a pressing fit. The wedge frame (37) and the push frame (16) are in a pressing fit. A fourth spring (38) is connected between the wedge frame (37) and the push plate (13).

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