A movable mold adjusting device for injection molding machine

Abstract

The present invention provides a movable mold adjusting device for an injection molding machine, belonging to the technical field of injection molds. The movable mold adjusting device for the injection molding machine comprises a movable mold plate, a slideway, and also comprises: an adjusting device, which is arranged between the slideway and the movable mold plate and is used to adjust the parallelism of the movable mold plate. The adjusting device comprises a sliding seat and an adjusting frame, and one end of the two are hinged to each other, wherein the movable mold plate is installed on the adjusting frame, an inclined groove is arranged on the adjusting frame, a sliding block is slidably arranged on the sliding seat through a first sliding rail, a sliding column capable of sliding inside the inclined groove is arranged on the sliding block, and a screw threadedly connected to the sliding column is arranged on the sliding seat; the device can lock the screw in the adjusting device, so that even if the screw is affected by external force caused by sliding or vibration of the movable mold plate, causing the screw to rotate, the position of the sliding block can still be guaranteed not to be offset, thereby maintaining the parallelism stability of the movable mold plate.

Description

Technical Field

[0001] The invention belongs to the technical field of injection molds, and in particular relates to a movable mold adjusting device of an injection molding machine. Background Art

[0002] The mold cavity formed by the movable mold and the fixed mold of the injection molding machine during the mold closing process is for the injection material to enter the mold cavity for molding to form the desired injection molded product. Since the injection molding part is assembled from multiple parts, certain errors are inevitable. These errors may cause deviations in the flatness between the movable mold and the fixed mold, or even misalignment of the center position of the movable mold and the fixed mold, deviations in the flatness or center position of the two molds, center deviations that make it impossible to align the mold, parallelism deviations that make it impossible to fit the mold or severe uneven force that produces flash and uneven wall thickness that makes it impossible to perform injection molding production.

[0003] A Chinese patent with the authorization announcement number CN106029332B discloses an injection molding machine, which comprises: a movable template on which a movable mold is installed and a support frame supporting the movable template, wherein a first support pin with the left-right direction of the movable template as the axial direction and a second support pin with the up-down direction of the movable template as the axial direction are provided on the support frame arranged on the side of the movable template. The first support pin supports the movable template rotatably in the pitch direction. The second support pin supports the support frame rotatably supporting the movable template in the pitch direction rotatably in the spiral direction, thereby ensuring the parallelism between the fixed mold and the movable mold to improve the quality of the molded body formed by the mold.

[0004] The above technical solution uses bolts to adjust the angle of the template, and most molds currently also use bolts to adjust the angle of the template. However, due to the frequent reciprocating motion of the template during mold closing and mold opening, the bolts are prone to loosening. In the long-term use process, this loosening phenomenon will cause the parallelism of the template to be unable to be effectively guaranteed, and thus make the injection molded product prone to flash problems. Summary of the invention

[0005] The object of the present invention is to provide a movable mold adjustment device for an injection molding machine, aiming to solve the problem that the injection molding machine in the prior art is prone to loosening of bolts after long-term use, and the parallelism of the template cannot be guaranteed, thereby making the injection molded product prone to flash.

[0006] To achieve the above object, the present invention provides the following technical solution: a movable mold adjustment device for an injection molding machine, comprising a movable mold plate, a slideway, and further comprising:

[0007] An adjusting device is arranged between the slideway and the movable template, and is used to adjust the parallelism of the movable template. The adjusting device includes a sliding seat and an adjusting frame, and one end of the two is hinged to each other, wherein the movable template is installed on the adjusting frame, and an inclined groove is arranged on the adjusting frame, and a slider is slidably arranged on the sliding seat through a first slide rail, and a sliding column capable of sliding inside the inclined groove is arranged on the sliding block, and a screw threadedly connected to the sliding column is arranged on the sliding seat;

[0008] A self-locking mechanism is arranged on the adjusting device and is used to fix the angle after the adjusting device is adjusted. The self-locking mechanism includes a rotating rod and a screw rod arranged on the sliding seat. The axes of the rotating rod and the screw rod are arranged parallel to each other. Two mutually meshing first gears and second gears are arranged in the sliding block. The first gear and the second gear can both rotate inside the sliding block. The screw rod is connected to the first gear through a thread. The rotating rod can make the axis of the second gear slide thereon. A clutch structure is arranged at one end of the screw rod and the rotating rod. When the clutch structure is in a meshing state, it can make the rotating rod and the screw rotate synchronously.

[0009] A further technical solution of the present invention is that the clutch structure includes a first meshing wheel and a second meshing wheel, the first meshing wheel is arranged at one end of the screw rod, the second meshing wheel is arranged at one end of the rotating rod, the rotating rod can slide along its own axis on the sliding seat, the sliding seat is provided with a top block, and the sliding seat is provided with an elastic member capable of pushing the top block close to the second meshing wheel.

[0010] A further technical solution of the present invention is that the first meshing wheel and the second meshing wheel are two oppositely arranged frustums, and the elastic member enables the inclined surfaces to contact each other and generate friction.

[0011] A further technical solution of the present invention is that friction surfaces are added to the contact surfaces of the two cones of the first meshing wheel and the second meshing wheel, and the friction surfaces are preferably made of rubber.

[0012] A further technical solution of the present invention is that two connecting blocks are arranged on the sliding seat, the screw rod and the rotating rod are both installed on the sliding seat through the connecting blocks, and the rotating rod can slide along its own axis on the connecting blocks.

[0013] A further technical solution of the present invention is that a supporting structure is provided on the adjusting device for supporting the end of the adjusting frame away from the hinged end of the sliding seat, the supporting structure includes a plug block, a frame is provided at one end of the adjusting frame, the plug block is located between the frame connecting blocks, the side surface of the connecting block is provided as an inclined surface, a rack is provided on the inclined surface of the plug block, and a third gear is provided on the rotating rod that can be disengaged from the rack.

[0014] A further technical solution of the present invention is that the plug block is in a right-angled trapezoidal shape, and its inclined surface is tightly fitted with the inclined surface of the connecting block.

[0015] A further technical solution of the present invention is that a friction layer is provided on a side of the plug that contacts the frame.

[0016] A further technical solution of the present invention is that one end of the screw rod and the rotating rod are both provided with a hexagonal hole.

[0017] A further technical solution of the present invention is that a slide groove is provided on the rotating rod, and a protrusion that can slide in the slide groove is provided on the second gear, so that the second gear can only slide along a predetermined path on the rotating rod.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The device can lock the screw in the adjusting device so that even if the screw is affected by external force caused by sliding or vibration of the movable plate, causing the screw to rotate, the position of the slider can still be guaranteed not to shift, thereby maintaining the parallelism stability of the movable plate.

[0020] 2. By setting up the supporting structure, as the distance between the frame and the bottom of the connecting block gradually decreases, the plug becomes tighter during the downward movement, thereby firmly locking one end of the adjusting frame on the connecting block, thereby achieving effective support for the adjusting frame and being able to effectively provide support for the suspended end of the adjusting frame, thereby preventing the adjusting frame from being deformed due to excessive force. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 It is a structural schematic diagram of a specific embodiment of the present invention;

[0023] Figure 2 It is a structural schematic diagram of the regulating device in a specific embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram of the internal structure of the regulating device in a specific embodiment of the present invention;

[0025] Figure 4 It is a structural schematic diagram of a self-locking mechanism in a specific embodiment of the present invention;

[0026] Figure 5 It is a structural schematic diagram of a support structure in a specific embodiment of the present invention;

[0027] Figure 6It is a schematic diagram of the installation structure of the rack and the third gear in a specific embodiment of the present invention.

[0028] In the figure: 1. movable template; 2. slideway; 3. adjusting device; 31. sliding seat; 311. connecting block; 32. adjusting frame; 321. inclined groove; 33. sliding block; 331. sliding column; 34. first slide rail; 35. screw; 4. self-locking mechanism; 41. rotating rod; 411. slideway; 42. first gear; 43. second gear; 5. clutch structure; 51. first meshing wheel; 52. second meshing wheel; 53. top block; 54. second slide rail; 55. elastic member; 56. friction surface; 6. supporting structure; 61. plug; 62. frame; 63. rack; 64. third gear. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] See also Figure 1-Figure 6 , the present invention provides the following technical solutions: a movable mold adjustment device for an injection molding machine, comprising a movable mold plate 1, a slideway 2, an adjustment device 3 and a self-locking mechanism 4;

[0031] The adjusting device 3 is arranged between the slide 2 and the movable template 1. The movable template 1 is installed on the adjusting device 3, and the adjusting device 3 can slide on the slide 2. The angle of the movable template 1 can be adjusted by the adjusting device 3. The self-locking mechanism 4 is arranged on the adjusting device 3 to fix the adjusted angle of the adjusting device 3 to avoid the loosening of the adjusting device 3 after the movable template 1 moves for a long time.

[0032] See also Figure 2-Figure 3 The adjusting device 3 is mainly composed of a sliding seat 31 and an adjusting frame 32. One end of the adjusting frame 32 is connected to one end of the sliding seat 31 in a hinged manner, and the sliding seat 31 is a strip structure and can slide on the slideway 2. The movable plate 1 is installed on the adjusting frame 32. By adjusting the angle between the adjusting frame 32 and the sliding seat 31, the tilt angle of the movable plate 1 can be adjusted, thereby achieving accurate calibration of the parallelism of the movable plate 1.

[0033] In order to adjust the angle of the adjustment frame 32, an inclined groove 321 is provided on the adjustment frame 32. The inclined groove 321 starts from one end where the adjustment frame 32 is hinged with the sliding seat 31 and gradually tilts downward toward the other end. The slider 33 and the first slide rail 34 are installed on the sliding seat 31. The first slide rail 34 is fixed to the sliding seat 31 by bolts and extends along the length direction of the sliding seat 31. The slider 33 is installed on the first slide rail 34 and can slide freely along the length direction of the first slide rail 34;

[0034] A slide post 331 is provided on both sides of the slider 33, and the slide post 331 can slide smoothly inside the inclined groove 321. In addition, a screw rod 35 is provided on the sliding seat 31, and the screw rod 35 is also provided along the length direction of the first slide rail 34. The slider 33 is connected to the screw rod 35 through a thread, so that the slider 33 can move on the screw rod 35. For easy operation, a hexagonal hole is provided at one end of the screw rod 35 so that a hexagonal wrench can be used for rotation operation;

[0035] During operation, the screw rod 35 can be driven to rotate by using the hexagonal wrench and the hexagonal hole. As the screw rod 35 rotates, it further drives the slider 33 to slide smoothly on the first slide rail 34. This action causes the slider 33 on the first slide rail 34 to drive the slide post 331 thereon to slide inside the inclined groove 321. Since the inclined groove 321 is arranged in an inclined manner, the movement of the slide post 331 in the inclined groove 321 can be converted into a driving force for the adjustment frame 32, causing it to rotate at the hinge point of the sliding seat 31. This rotation action further realizes the fine adjustment of the parallelism of the movable template 1 on the adjustment frame 32.

[0036] See also Figure 3-Figure 4 Although the screw 35 has a certain self-locking performance during use, thereby effectively slowing down the sliding tendency of the slide column 331 on the first slide rail 34, however, with the continuous mold closing and mold opening actions of the movable mold plate 1, the slider 33 will inevitably produce slight shaking or vibration on the first slide rail 34. This long-term small cumulative effect may induce the screw 35 to rotate, which in turn has an adverse effect on the parallelism stability of the movable mold plate 1. In order to properly solve this potential problem, a self-locking mechanism 4 is added to the adjustment device 3. The introduction of this mechanism ensures that even if the screw 35 is affected by the external force caused by the sliding or vibration of the slider 33, which causes the screw 35 to rotate, the position of the slider 33 can still be guaranteed not to shift, thereby maintaining the parallelism stability of the movable mold plate 1.

[0037] The self-locking mechanism 4 includes a rotating rod 41, which is arranged parallel to the axis of the screw rod 35. A hexagonal hole is arranged at one end of the rotating rod 41, and the hole is located on the same side as the hexagonal hole on the screw rod 35, which is convenient for operation. Two connecting blocks 311 are arranged on the sliding seat 31, and the screw rod 35 and the rotating rod 41 are both flexibly rotated and installed through the connecting blocks 311, ensuring that they are integrated on the sliding seat 31;

[0038] An installation chamber is provided inside the slider 33, in which two mutually meshing first gears 42 and second gears 43 are provided, both of which can rotate inside the slider 33. In particular, the screw 35 is connected to the axis of the first gear 42 by a thread, and the rotating rod 41 allows the axis of the second gear 43 to slide thereon instead of being fixed. In order to realize this sliding mechanism, a slide groove 411 is provided on the rotating rod 41, and a protrusion that can slide in the slide groove 411 is provided on the second gear 43. Such a design ensures that the second gear 43 can only slide along a predetermined path on the rotating rod 41. A clutch structure 5 is provided at the other end of the screw 35 and the rotating rod 41 away from the hexagonal hole. When this clutch structure 5 is in a meshing state, it can enable the rotating rod 41 and the screw 35 to rotate synchronously;

[0039] When the angle of the movable template 1 needs to be adjusted, the clutch structure 5 must first be disengaged from its mutually meshed state. Subsequently, two hexagonal wrenches are used to be inserted into the hexagonal holes at one end of the screw 35 and the rotating rod 41, respectively, to fix the rotating rod 41 to prevent it from rotating. Through the matching design of the slide groove 411 and the protrusion, the rotation of the second gear 43 can also be effectively prevented. Since the first gear 42 and the second gear 43 are meshed with each other, the first gear 42 is also in a non-rotatable state. Next, the screw 35 is rotated by the hexagonal wrench to generate relative movement between it and the first gear 42, thereby driving the first gear 42 to move along the length direction of the screw 35. When the first gear 42 moves, it drives the slider 33 to slide on the first slide rail 34, thereby realizing the adjustment of the angle of the movable template 1;

[0040] When the adjusting device 3 is locked, the clutch structure 5 will re-enter the mutually meshed state and cancel the fixation of the rotating rod 41. At this time, if the screw rod 35 rotates due to shaking or vibration, its rotation will be transmitted to the rotating rod 41 through the clutch structure 5, so that the rotating rod 41 rotates synchronously. The rotation of the rotating rod 41 then drives the second gear 43 to rotate. Since the first gear 42 and the second gear 43 are meshed with each other, the first gear 42 will also rotate synchronously. In this way, during the rotation of the screw rod 35, the first gear 42 can rotate synchronously with the screw rod 35 to ensure that there is no relative rotation between them. Therefore, the first gear 42 will not move horizontally on the screw rod 35, thereby preventing the slider 33 from sliding on the first slide rail 34. Therefore, even if the screw rod 35 rotates, it will not cause the slider 33 to slide on the first slide rail 34, thereby achieving the locked state of the slider 33 and effectively preventing the slider 33 from accidentally sliding on the first slide rail 34.

[0041] It should be noted that the slider 33 can be formed by splicing two left and right shells. Such a design facilitates the placement of the first gear 42 and the second gear 43 inside the installation chamber. During the installation process, the left and right ends of the first gear 42 and the second gear 43 will be close to the inner wall of the installation chamber, thereby effectively preventing them from sliding unnecessarily in the installation chamber. Subsequently, the left and right shells are firmly fixed together by screws to complete the secure installation of the first gear 42 and the second gear 43.

[0042] Please continue reading Figure 3-Figure 4 The clutch structure 5 is mainly composed of a first meshing wheel 51 and a second meshing wheel 52. The first meshing wheel 51 is firmly connected to the end of the screw rod 35 away from the inner hexagonal hole, and the second meshing wheel 52 is firmly installed on the end of the rotating rod 41 away from the inner hexagonal hole. The rotating rod 41 can slide smoothly along its own axis on the two connecting blocks 311. This sliding mechanism enables the first meshing wheel 51 and the second meshing wheel 52 to flexibly achieve meshing and separation;

[0043] In order to ensure that the first meshing wheel 51 can stably maintain the meshing state with the second meshing wheel 52, a top block 53 is provided on the sliding seat 31. The top block 53 can move smoothly on the sliding seat 31 under the guidance of the second slide rail 54. In addition, the sliding seat 31 is also equipped with an elastic member 55, specifically a compression spring, for pushing the top block 53. One end of the elastic member 55 is fixed on the top block 53, and the other end is connected to the extension plate extending from the sliding seat 31;

[0044] Thanks to the elastic force of the elastic member 55, the top block 53 can effectively push the second meshing wheel 52 to mesh tightly with the first meshing wheel 51. This ensures that the first meshing wheel 51 and the second meshing wheel 52 can always maintain a good meshing state, thereby achieving the expected function of the clutch structure 5.

[0045] The first meshing wheel 51 and the second meshing wheel 52 can be designed as two oppositely arranged frustum shapes, whose inclined surfaces can contact each other and generate friction. The synergistic effect of the elastic member 55 and the top block 53 can ensure that the two frustums always remain in contact. In order to further enhance the friction between them, a friction surface 56 can be added to the contact surface of the frustum. The friction surface 56 is preferably made of rubber material. By utilizing the high friction characteristics of rubber, the screw 35 and the rotating rod 41 can achieve synchronous rotation through friction.

[0046] In addition, the first meshing wheel 51 and the second meshing wheel 52 can also be replaced by two spur gears of the same size. In this case, the screw 35 and the rotating rod 41 can also be rotated synchronously by the precise meshing between the spur gears. Both of these embodiments can effectively achieve the purpose of synchronous rotation, but are not limited to these two embodiments. According to the needs of specific application scenarios, the most suitable solution can be selected for implementation.

[0047] See also Figure 5 and Figure 6 Since the adjustment frame 32 is arranged in a long strip shape and the movable plate 1 is installed on the adjustment frame 32, after the parallelism of the movable plate 1 is adjusted by the adjustment frame 32, one end of the adjustment frame 32 will be in a suspended state. When the movable plate 1 is in a mold closing operation, a huge force will be generated, which may cause the adjustment frame 32 in a suspended state to be subjected to excessive pressure and bend and deform. In order to avoid this situation, a support structure 6 is added to the end of the adjustment frame 32 away from the hinged end with the sliding seat 31. The support structure 6 can effectively provide support for the suspended end of the adjustment frame 32, thereby preventing the adjustment frame 32 from being deformed due to excessive force.

[0048] The support structure 6 includes a plug block 61, wherein a frame 62 is designed at one end of the adjustment frame 32 near the inner hexagonal hole. The plug block 61 is placed between the frame 62 and the connecting block 311 adjacent to the inner hexagonal hole. The side of the connecting block 311 is set as an inclined surface structure, so that the distance between it and the frame 62 gradually decreases from top to bottom. The plug block 61 itself presents a right-angled trapezoid, and its inclined surface is closely fitted with the inclined surface of the connecting block 311.

[0049] A rack 63 is arranged on the inclined surface of the plug 61, and a third gear 64 is installed on the rotating rod 41. The working mechanism is as follows: when the first meshing wheel 51 and the second meshing wheel 52 are in meshing state, the third gear 64 and the rack 63 are staggered from each other; when the two meshing wheels are separated, the third gear 64 is meshed with the rack 63.

[0050] Once the parallelism of the movable platen 1 is adjusted, the operator can use the hexagonal wrench to push the third gear 64 into meshing with the rack 63, and then rotate the third gear 64. This action drives the rack 63 and the plug 61 connected thereto to move downward between the frame 62 and the connecting block 311. As the distance between the frame 62 and the bottom of the connecting block 311 gradually decreases, the plug 61 becomes tighter during the downward movement, thereby firmly locking one end of the adjustment frame 32 on the connecting block 311, thereby achieving effective support for the adjustment frame 32.

[0051] After the support is completed, the operator can loosen the rotating rod 41, and the elastic member 55 will play a role, so that the third gear 64 and the rack 63 are automatically staggered.

[0052] Furthermore, in order to avoid relative sliding between the plug 61 and the frame 62 , a friction layer is provided on the contacting surface of the plug 61 and the frame 62 to prevent relative sliding between the plug 61 and the frame 62 .

Claims

1. A movable mold adjusting device for an injection molding machine, comprising a movable mold plate (1) and a slideway (2), characterized in that: Also includes: An adjusting device (3) is arranged between the slideway (2) and the movable template (1) and is used to adjust the parallelism of the movable template (1). The adjusting device (3) comprises a sliding seat (31) and an adjusting frame (32), and one end of the two are hingedly connected to each other, wherein the movable template (1) is mounted on the adjusting frame (32), the adjusting frame (32) is provided with an inclined groove (321), a sliding block (33) is slidably arranged on the sliding seat (31) via a first sliding rail (34), a sliding column (331) capable of sliding inside the inclined groove (321) is arranged on the sliding block (33), and a screw rod (35) threadedly connected to the sliding column (331) is arranged on the sliding seat (31); The self-locking mechanism (4) is arranged on the adjusting device (3) and is used to fix the angle after the adjusting device (3) is adjusted. The self-locking mechanism (4) comprises a rotating rod (41) and a screw rod (35) arranged on the sliding seat (31). The axes of the rotating rod (41) and the screw rod (35) are arranged parallel to each other. Two mutually meshing first gears (42) and second gears (43) are arranged in the sliding block (33). Both the first gear (42) and the second gear (43) can rotate in the sliding block (33). The screw rod (35) is connected to the first gear (42) through a thread. The rotating rod (41) can make the axis of the second gear (43) slide thereon. A clutch structure (5) is arranged at one end of the screw rod (35) and the rotating rod (41). When the clutch structure (5) is in a meshing state, it can make the rotating rod (41) and the screw rod (35) rotate synchronously.

2. The movable mold adjusting device of an injection molding machine according to claim 1, characterized in that: The clutch structure (5) comprises a first meshing wheel (51) and a second meshing wheel (52); the first meshing wheel (51) is arranged at one end of the screw rod (35); the second meshing wheel (52) is arranged at one end of the rotating rod (41); the rotating rod (41) is capable of sliding on the sliding seat (31) along its own axis; a top block (53) is arranged on the sliding seat (31); and an elastic member (55) capable of pushing the top block (53) close to the second meshing wheel (52) is arranged on the sliding seat (31).

3. A movable mold adjusting device for an injection molding machine according to claim 2, characterized in that: The first meshing wheel (51) and the second meshing wheel (52) are two oppositely arranged frustums, and the elastic member (55) enables the inclined surfaces to contact each other and generate friction.

4. The movable mold adjusting device of an injection molding machine according to claim 3, characterized in that: Friction surfaces (56) are added to the contact surfaces of the two cones of the first meshing wheel (51) and the second meshing wheel (52), and the friction surfaces (56) are made of rubber.

5. The movable mold adjusting device of an injection molding machine according to claim 2, characterized in that: Two connecting blocks (311) are provided on the sliding seat (31), and the screw rod (35) and the rotating rod (41) are both mounted on the sliding seat (31) via the connecting blocks (311), and the rotating rod (41) can slide on the connecting blocks (311) along its own axis.

6. The movable mold adjusting device of an injection molding machine according to claim 1, characterized in that: The adjusting device (3) is provided with a support structure (6) for supporting an end of the adjusting frame (32) away from the hinged connection with the sliding seat (31), the support structure (6) comprising a plug (61), a frame (62) being provided at one end of the adjusting frame (32), the plug (61) being located between the frame (62) and the connecting block (311), the side surface of the connecting block (311) being provided with an inclined surface, a rack (63) being provided on the inclined surface of the plug (61), and a third gear (64) being disengageable from the rack (63) being provided on the rotating rod (41).

7. The movable mold adjusting device of an injection molding machine according to claim 6, characterized in that: The plug block (61) is in the shape of a right-angled trapezoid, and its inclined surface is tightly fitted with the inclined surface of the connecting block (311).

8. The movable mold adjusting device of an injection molding machine according to claim 6, characterized in that: A friction layer is provided on the surface of the plug (61) that contacts the frame (62).

9. The movable mold adjusting device of an injection molding machine according to claim 1, characterized in that: One end of the screw rod (35) and the rotating rod (41) is provided with a hexagonal hole.

10. A movable mold adjusting device for an injection molding machine according to any one of claims 1 to 9, characterized in that: The rotating rod (41) is provided with a sliding groove (411), and the second gear (43) is provided with a protrusion that can slide in the sliding groove (411), so that the second gear (43) can only slide along a predetermined path on the rotating rod (41).

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