Low-pressure injection molding device for automotive upholstery

Abstract

The invention relates to the technical field of low-pressure injection molding, in particular to a low-pressure injection molding device for automotive upholstery, which is mainly characterized in that an injection molding auxiliary mechanism is arranged at the position of an injection molding opening in the side wall of a top mold to assist the injection molding of the automotive upholstery. After the materials are guided in, the position of the auxiliary sealing body is controlled through the regulation and control assembly, so that the auxiliary sealing body shields and blocks the injection molding opening; on the other hand, the cleaning structure is arranged in the bearing box body, so that the injection molding opening can be correspondingly cleaned when the injection molding opening is blocked; furthermore, a conveying air pipe is arranged on the side of the bearing box body, the conveying air pipe is matched with a vent hole and a communication conveying opening in the sealing cover for use, and cooling air is introduced, so that the cooling efficiency can be improved; the invention provides an injection molding auxiliary mechanism to improve the product forming efficiency. And therefore, the positive influence on the product processing benefit is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of low-pressure injection molding, in particular to a low-pressure injection molding device for automobile interior decoration parts. Background Art

[0002] The existing document with announcement number CN115179507A discloses a low-pressure injection molding device and injection molding method for an automobile instrument panel, the scheme of which includes a device base, a support frame is fixedly provided on the top of the device base, a controller is provided on the front surface of the support frame, a driving cylinder is installed on the top of the support frame, an upper injection molding template is fixedly provided on the output end of the driving cylinder, an injection molding port is fixedly communicated with the side of the upper injection molding template, a plurality of groups of down-pressing rods are installed on the bottom of the upper injection molding template, and a lower injection molding template is embedded and installed on the top of the device base; the scheme of which is under the action of the down-pressing rod, the down-pressing hole, the stripping module, the stripping hole, the installation cavity, the tension spring, the positioning groove, and the positioning plate, so that when the upper injection molding template is separated from the injection molded product, under the action of the stripping module, the lower injection molding template and the injection molded product are separated at the same time, and the operation method is fast and convenient, so as to improve the effect of the staff's shedding, thereby improving the production effect of the injection molded product.

[0003] The above-mentioned scheme and the vertical low-pressure injection molding device in the prior art perform injection molding through the injection port arranged on the side of the upper mold body after the upper mold body is docked with the lower mold body. After the injection molding is completed, the mold is opened after the material is cooled, and finally the molded product is taken out. In this process, after the material is injected from the injection port, the feed port of the material introduction device is docked with the injection port. After the material is introduced, the feed port of the material introduction device will be separated from the injection port, and the material will be introduced again after the product is formed. On the one hand, there is a lack of a suitable blocking mechanism for the injection port to prevent external impurities from entering the mold from the injection port; on the other hand, the natural cooling efficiency is low, which affects the product molding efficiency; and thus has a negative impact on the product processing efficiency.

[0004] To this end, the present invention proposes a low-pressure injection molding device for automobile interior decoration parts to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a low-pressure injection molding device for automobile interior decoration parts to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solutions: a low-pressure injection molding device for automobile interior decoration, comprising an injection molding device workbench, on which a support column, a guide rod and a bottom mold are arranged, the top mold is connected to a lifting drive shaft, and an injection port is arranged on one side of the top mold; the side wall of the top mold is provided with an injection molding auxiliary mechanism; The injection molding auxiliary mechanism includes a carrying box body, a regulating component and an auxiliary structure; The box body of the carrying box body is provided with a docking port, and a fixed side edge is fixedly provided at the box opening position of the carrying box body, and the fixed side edge is fixedly provided on the side wall of the top mold by fastening screws.

[0007] Preferably, a nozzle is provided on one side of the carrier box body, and an air delivery pipe is provided at the outer opening of the nozzle, and the docking port is provided as a circular port, and the docking port corresponds to the setting position of the injection port.

[0008] Preferably, the regulating component includes a regulating handle, an extension protrusion, a cylindrical slot, a positioning pin, a pull head, a positioning slot, a connecting shaft, an extension plate and a first docking plate; the connecting shaft is plugged into the carrying box body, and a regulating handle is fixedly provided at one end of the connecting shaft, an extension protrusion is fixedly provided on the side wall of the regulating handle, a cylindrical slot is penetrated through the extension protrusion, a pull head is fixedly provided at one end of the positioning pin, and the positioning slot is equidistantly provided on the outer wall of the carrying box body.

[0009] Preferably, the other end of the connecting shaft body extends into the inner cavity of the carrying box body, and the side wall of the connecting shaft body is symmetrically fixedly provided with an extension plate, and the end of the extension plate is fixedly provided with a first docking plate.

[0010] Preferably, the notch of the positioning slot is set to be circular, the positioning pin is adapted to be plugged into the cylindrical slot, and one end of the positioning pin is plugged into the positioning slot.

[0011] Preferably, the first docking plate is connected to an auxiliary structure, and the auxiliary structure includes a second docking plate, a fixed plate, an auxiliary sealing body, a accommodating cavity, a cover, mounting screws, auxiliary circular holes, air vents, a connecting conveying port and a cleaning structure; the second docking plate is fixedly arranged at one end of the fixed plate, and the other end of the fixed plate is fixedly arranged with an auxiliary sealing body, and the second docking plate is fixedly connected to the first docking plate by bolts.

[0012] Preferably, a accommodating cavity is provided in the auxiliary sealing body, and a mounting thread groove is provided on the auxiliary sealing body, mounting holes are symmetrically provided in the cover, and a placement groove is provided at the opening position of one end of the mounting hole, the cover is fixedly connected to the auxiliary sealing body by mounting screws, and a connecting conveying port is provided on the side wall of the auxiliary sealing body, and the connecting conveying port corresponds to the setting position of the nozzle; two auxiliary sealing bodies are provided in the accommodating cavity.

[0013] Preferably, the sealing cover is provided with an auxiliary circular hole and a vent hole; the containing cavity is provided with a cleaning structure; and the vent hole is connected to the containing cavity in the auxiliary sealing body.

[0014] Preferably, the cleaning structure includes a limiting sleeve, a limiting pin body, an auxiliary spring, a fixed plate, an auxiliary sphere and cleaning bristles; the limiting sleeve is fixedly arranged in the accommodating cavity, one end of the limiting pin body is fixedly arranged with an auxiliary spring, and the other end of the auxiliary spring is fixedly arranged with a fixed plate, and the end face of the other end of the limiting pin body is arranged with an auxiliary sphere; and the auxiliary sphere is arranged with cleaning bristles.

[0015] Preferably, the limit pin body is placed in a limit sleeve, and one limit pin body is placed in a limit sleeve; the auxiliary sphere at the end of the limit pin body corresponds to the setting position of the auxiliary circular hole on the cover, and the setting group number is the same.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The low-pressure injection molding device for automobile interior decoration parts designed by the present invention mainly provides an auxiliary injection molding mechanism at the injection molding port position on the side wall of the top mold to provide auxiliary effects on the injection molding processing of automobile interior decoration parts. On the one hand, the auxiliary seal has a blocking effect on the injection molding port through the arranged auxiliary seal. After the material is introduced, the position of the auxiliary seal is controlled by the regulating component so that the auxiliary seal blocks and blocks the injection molding port; on the other hand, by arranging a cleaning structure in the supporting box body, when the injection molding port is blocked, the injection molding port can also be cleaned accordingly; furthermore, by arranging a conveying air pipe on the side of the supporting box body, the conveying air pipe is used in conjunction with the vent hole on the cover and the connecting conveying port to pass cooling gas, thereby improving its cooling efficiency; the present invention provides an injection molding auxiliary mechanism to improve product molding efficiency; thereby having a positive impact on product processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structural connection of the low-pressure injection molding device of the present invention; Figure 2 It is a side view of the structural connection of the low-pressure injection molding device of the present invention; Figure 3 For the present invention Figure 2 A magnified schematic diagram of the structural connection at center A; Figure 4 This is a schematic diagram of the outer side of the injection molding auxiliary mechanism structure connection of the present invention; Figure 5 For the present invention Figure 4 A magnified schematic diagram of the structural connection at B in the middle; Figure 6 This is a schematic diagram of the inner side of the structure connection of the injection molding auxiliary mechanism of the present invention; Figure 7 For the present invention Figure 6 A magnified schematic diagram of the structural connection at C in the middle; Figure 8 This is an exploded top view of the auxiliary structure connection of the present invention; Fig. 9 For the present invention Figure 8 The enlarged schematic diagram of the structural connection at D in the middle; Fig.10 For the present invention Figure 8 The enlarged schematic diagram of the structural connection at E in the middle; Fig.11 This is an exploded bottom view of the auxiliary structure connection of the present invention; Fig.12 It is a schematic diagram of the connection of the limit pin structure in the cleaning structure of the present invention.

[0018] In the figure: an injection molding device workbench 1, a support column 2, a guide rod 3, a bottom mold 4, a top mold 5, an injection port 51, a lifting drive shaft 6, a carrier box 601, a docking port 602, a fixed side 603, a fastening screw 604, a delivery air pipe 605, a nozzle 606, a regulating handle 701, an extension convex body 702, a cylindrical slot 703, a positioning pin 704, a pull head 705, a positioning slot 706, a connecting shaft 707, an extension plate 708, a first docking plate 709, a second docking plate 801, a fixing plate 802, an auxiliary sealing body 803, a containing cavity 804, a cover 805, a mounting screw 806, an auxiliary circular hole 807, a vent hole 808, a connecting delivery port 809, a limiting sleeve 901, a limiting pin body 902, an auxiliary spring 903, a fixing plate 904, an auxiliary sphere 905, and cleaning soft hair 906. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. The embodiments of the present invention and all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0020] Example 1: Please refer to Figure 1-Figure 12 A low-pressure injection molding device for automobile interior decoration parts includes an injection molding device workbench 1, on which a support column 2, a guide rod 3 and a bottom mold 4 are arranged, a top mold 5 is connected to a lifting drive shaft 6, and an injection port 51 is arranged on one side of the top mold 5; an injection molding auxiliary mechanism is arranged on the side wall of the top mold 5; wherein the top mold 5 is driven to lift by the lifting drive shaft 6, and the lifting drive shaft 6 controls the mold closing and mold opening of the top mold 5 and the bottom mold 4. After the top mold 5 and the bottom mold 4 are closed, the material is input from the injection port 51 on the side of the top mold 5 through the material introduction device. After the material is introduced, the injection port 51 is blocked and cleaned by the provided injection molding auxiliary mechanism, and it can also provide a cooling auxiliary function.

[0021] The injection molding auxiliary mechanism here includes a supporting box body 601, a regulating component and an auxiliary structure; therefore, the present invention mainly arranges an injection molding auxiliary mechanism at the position of the injection port 51 on the side wall of the top mold 5 to provide auxiliary effects on the injection molding processing of automobile interior decoration parts. On the one hand, the auxiliary seal 803 is provided to have a blocking effect on the injection port 51. After the material is introduced, the position of the auxiliary seal 803 is controlled by the regulating component, so that the auxiliary seal 803 blocks and blocks the injection port 51; on the other hand, by arranging a cleaning structure in the supporting box body 601, when the injection port 51 is blocked, the injection port 51 can also be cleaned accordingly; furthermore, by arranging an air delivery pipe 605 on the side of the supporting box body 601, the air delivery pipe 605 is used in conjunction with the vent hole 808 and the connecting delivery port 809 on the cover 805 to introduce cooling gas, thereby improving its cooling efficiency.

[0022] Example 2: Based on Example 1, please refer to Figure 3-Figure 12 Here, a docking port 602 is provided on the box body of the supporting box body 601, and a fixed side edge 603 is fixedly provided at the box mouth position of the supporting box body 601, and the fixed side edge 603 is fixedly provided on the side wall of the top mold 5 by a fastening screw 604; here, a nozzle 606 is provided on one side of the supporting box body 601, and a conveying air pipe 605 is provided at the outer orifice position of the nozzle 606, and the docking port 602 is set as a circular port, and the docking port 602 corresponds to the setting position of the injection port 51.

[0023] The regulating assembly here includes a regulating handle 701, an extension convex body 702, a cylindrical slot 703, a positioning pin 704, a pull head 705, a positioning slot 706, a connecting shaft 707, an extension plate 708 and a first docking plate 709; the connecting shaft 707 is inserted and arranged in the carrier box body 601, and the regulating handle 701 is fixedly arranged at one end of the connecting shaft 707, and the side wall of the regulating handle 701 is fixedly arranged with an extension convex body 702, and the cylindrical slot 703 is penetrated in the extension convex body 702, and the pull head 705 is fixedly arranged at one end of the positioning pin 704, and the positioning slot 706 is equidistantly arranged on the outer side wall of the carrier box body 601; here, the other end of the connecting shaft 707 extends into the inner cavity of the carrier box body 601, and the side of the connecting shaft 707 An extension plate 708 is symmetrically fixedly provided on the wall, and a first docking plate 709 is fixedly provided on the end of the extension plate 708; the notch of the positioning slot 706 here is set to be circular, the positioning pin 704 is adapted to be plugged into the cylindrical slot 703, and one end of the positioning pin 704 is engaged with the positioning slot 706; wherein four positioning slots 706 are equidistantly arranged on the carrier box body 601, that is, the regulating handle 701 only needs to be rotated 90 degrees each time, and an extension protrusion 702 is arranged on the side of the regulating handle 701 here, on the one hand, it is for use in conjunction with the positioning pin 704 to realize the position positioning of the regulating handle 701; furthermore, the extension protrusion 702 can also provide an auxiliary effect on the rotation of the regulating handle 701, thereby improving the convenience of its rotation operation.

[0024] The first docking plate 709 is connected to the auxiliary structure, which includes a second docking plate 801, a fixed plate 802, an auxiliary sealing body 803, a containing cavity 804, a cover 805, mounting screws 806, an auxiliary circular hole 807, a vent hole 808, a connecting delivery port 809 and a cleaning structure; the second docking plate 801 is fixedly arranged at one end of the fixed plate 802, and the other end of the fixed plate 802 is fixedly arranged with the auxiliary sealing body 803, and the second docking plate 801 is fixedly connected to the first docking plate 709 by bolts; the containing cavity 804 is arranged in the auxiliary sealing body 803, and the auxiliary sealing body 803 is provided with a A mounting thread groove is provided, mounting holes are symmetrically provided in the cover 805, and a placement groove is provided at the opening position of one end of the mounting hole, the cover 805 is fixedly connected to the auxiliary seal 803 by means of mounting screws 806, a connecting delivery port 809 is provided on the side wall of the auxiliary seal 803, and the connecting delivery port 809 corresponds to the setting position of the nozzle 606; two auxiliary seals 803 are provided in the accommodating cavity 804; an auxiliary circular hole 807 and a vent hole 808 are provided on the cover 805; a cleaning structure is provided in the accommodating cavity 804; the vent hole 808 is connected to the accommodating cavity 804 in the auxiliary seal 803.

[0025] The cleaning structure here includes a limiting sleeve 901, a limiting pin body 902, an auxiliary spring 903, a fixed plate 904, an auxiliary ball 905 and cleaning soft hair 906; the limiting sleeve 901 is fixedly arranged in the accommodating cavity 804, one end of the limiting pin body 902 is fixedly arranged with an auxiliary spring 903, and the other end of the auxiliary spring 903 is fixedly arranged with a fixed plate 904, and the end surface of the other end of the limiting pin body 902 is arranged with an auxiliary ball 905; the auxiliary ball 905 is arranged with cleaning soft hair 906; the limiting pin body 902 here is placed in the limiting sleeve 901, and one limiting pin body 902 is placed in a limiting sleeve 901; the end of the limiting pin body 902 The auxiliary sphere 905 in the part and the auxiliary circular holes 807 on the cover 805 are arranged in corresponding positions and have the same number of groups; after the limiting pin body 902 is placed into the limiting sleeve 901, the cover 805 is covered on the auxiliary cover 803, and the cover 805 is fixed on the auxiliary cover 803 by installing screws 806. At the same time, when the cover 805 is pressed on the auxiliary cover 803, the auxiliary circular holes 807 arranged on the cover 805 are stuck on the auxiliary sphere 905, where the ball diameter of the auxiliary sphere 905 is larger than the aperture diameter of the auxiliary circular holes 807, and when the cover 805 is installed, the auxiliary spring 903 connected to the limiting pin body 902 is in a compressed state.

[0026] In this embodiment, after the material input device introduces the material from the injection port 51 on the side wall of the top mold 5, the material input port of the material input device is separated from the injection port 51. At the same time, the connecting shaft 707 is driven to rotate by rotating the regulating handle 701, and the connecting shaft 707 drives the auxiliary sealing body 803 to move. When one of the auxiliary sealing bodies 803 moves to the docking port 602 position on the carrier box body 601 and blocks it, the extended protrusion 702 set on the side of the regulating handle 701 reaches the positioning slot 706 position at the corresponding position during this process, and then the positioning pin 704 is used to insert into the cylindrical slot 703 in the extended protrusion 702, and the end of the positioning pin 704 is inserted into the positioning slot 706 to locate the position of the regulating handle 701, thereby realizing the position positioning of the auxiliary sealing body 803; at this time, the auxiliary sealing body 803 can block the injection port 51.

[0027] During this process, after the auxiliary sealing body 803 moves and completely blocks the injection port 51, the cleaning structure arranged in the auxiliary sealing body 803 also has a corresponding cleaning effect on the nozzle of the injection port 51, that is, it is achieved by the coordinated use of the set limit pin body 902, the auxiliary spring 903, the auxiliary ball 905 and the cleaning soft bristle 906, wherein the auxiliary spring 903 and the limit pin body 902 are used together to provide a flexible effect, which not only realizes the cleaning effect, but also has a protective effect on the injection port 51, and when it is necessary to release the blocking work of the auxiliary sealing body 803 on the injection port 51, continue to rotate the regulating handle 701 so that the position of the auxiliary sealing body 803 Move it out from the position of the injection port 51, that is, expose the injection port 51; before rotating the regulating handle 701, it is necessary to release the positioning of the regulating handle 701, that is, pull out the positioning pin 704 through the pull head 705, so that the position of the regulating handle 701 can be contacted; after the regulation work is completed, the regulating handle 701 is positioned again; the auxiliary seal 803 is detachably arranged to facilitate subsequent disassembly, maintenance and replacement; that is, two auxiliary seals 803 are arranged in the supporting box body 601, and the second docking plate 801 on the auxiliary seal 803 is fixedly connected to the first docking plate 709 by bolts, and the auxiliary seal 803 and the cover 805 are also detachably arranged.

[0028] After the auxiliary seal 803 seals the injection port 51, it is only necessary to wait for the material in the mold to cool down before opening the mold. At this time, the air delivery pipe 605 arranged on the side of the supporting box body 601 can deliver cooling gas, that is, the delivered cooling gas is ejected from the nozzle 606, and then enters the accommodating cavity 804 of the auxiliary seal 803 from the connecting delivery port 809 on the side of the auxiliary seal 803, and then is output from the vent hole 808 on the cover 805, thereby realizing auxiliary cooling of the material in the mold, further improving its product molding efficiency, and having a positive impact on improving its processing efficiency.

[0029] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-pressure injection molding device for automobile interior parts, comprising an injection molding device workbench (1), wherein the injection molding device workbench (1) is provided with a support column (2), a guide rod (3) and a bottom mold (4), wherein the top mold (5) is connected to a lifting drive shaft (6), and an injection port (51) is provided on one side of the top mold (5); the characteristics are: The side wall of the top mold (5) is provided with an injection molding auxiliary mechanism; The injection molding auxiliary mechanism comprises a carrying box body (601), a regulating component and an auxiliary structure; The box body of the carrying box body (601) is provided with a docking port (602), and a fixed side edge (603) is fixedly provided at the box opening of the carrying box body (601), and the fixed side edge (603) is fixedly provided on the side wall of the top mold (5) by means of a fastening screw (604).

2. A low-pressure injection molding device for automotive interior parts according to claim 1, characterized in that: A nozzle (606) is provided on one side of the carrier box body (601), and a conveying air pipe (605) is provided at the outer opening of the nozzle (606); the docking port (602) is provided as a circular port, and the docking port (602) corresponds to the position of the injection port (51).

3. The low-pressure injection molding device for automobile interior decoration parts according to claim 1, characterized in that: The regulating component comprises a regulating handle (701), an extending protrusion (702), a cylindrical slot (703), a positioning pin (704), a pull head (705), a positioning slot (706), a connecting shaft (707), an extending plate (708) and a first docking plate (709); the connecting shaft (707) is inserted into the carrying box body (601), and one end of the connecting shaft (707) is fixedly provided with the regulating handle (701), the side wall of the regulating handle (701) is fixedly provided with an extending protrusion (702), the extending protrusion (702) is penetrated by a cylindrical slot (703), one end of the positioning pin (704) is fixedly provided with the pull head (705), and the positioning slot (706) is equidistantly provided on the outer side wall of the carrying box body (601).

4. A low-pressure injection molding device for automotive interior parts according to claim 3, characterized in that: The other end of the connecting shaft body (707) extends into the inner cavity of the carrying box body (601), and an extension plate (708) is symmetrically fixedly provided on the side wall of the connecting shaft body (707), and a first docking plate (709) is fixedly provided at the end of the extension plate (708).

5. The low-pressure injection molding device for automobile interior decoration parts according to claim 3, characterized in that: The notch of the positioning slot (706) is arranged to be circular, the positioning pin (704) is adapted to be plugged into the columnar slot (703), and one end of the positioning pin (704) is plugged into the positioning slot (706).

6. The low-pressure injection molding device for automobile interior decoration parts according to claim 3, characterized in that: The first docking plate (709) is connected to an auxiliary structure, and the auxiliary structure comprises a second docking plate (801), a fixing plate (802), an auxiliary sealing body (803), a containing cavity (804), a sealing cover (805), mounting screws (806), auxiliary circular holes (807), vent holes (808), a connecting delivery port (809) and a cleaning structure; the second docking plate (801) is fixedly arranged at one end of the fixing plate (802), and the auxiliary sealing body (803) is fixedly arranged at the other end of the fixing plate (802); the second docking plate (801) is fixedly connected to the first docking plate (709) by bolts.

7. A low-pressure injection molding device for automobile interior decoration parts according to claim 6, characterized in that: The auxiliary sealing body (803) is provided with a receiving cavity (804), and the auxiliary sealing body (803) is provided with a mounting thread groove, the sealing cover (805) is symmetrically provided with mounting holes, and a placement groove is provided at the opening position of one end of the mounting hole, the sealing cover (805) is fixedly connected to the auxiliary sealing body (803) by means of mounting screws (806), the side wall of the auxiliary sealing body (803) is provided with a connecting delivery port (809), and the connecting delivery port (809) corresponds to the setting position of the nozzle (606); the auxiliary sealing body (803) is provided with two in the receiving cavity (804).

8. The low-pressure injection molding device for automobile interior decoration parts according to claim 6, characterized in that: The sealing cover (805) is provided with an auxiliary circular hole (807) and a vent hole (808); a cleaning structure is provided in the accommodating cavity (804); and the vent hole (808) is connected to the accommodating cavity (804) in the auxiliary sealing body (803).

9. The low-pressure injection molding device for automobile interior decoration parts according to claim 6, characterized in that: The cleaning structure comprises a limiting sleeve (901), a limiting pin body (902), an auxiliary spring (903), a fixed plate (904), an auxiliary ball (905) and cleaning bristles (906); the limiting sleeve (901) is fixedly arranged in the accommodating cavity (804); one end of the limiting pin body (902) is fixedly arranged with an auxiliary spring (903), and the other end of the auxiliary spring (903) is fixedly arranged with a fixed plate (904); the end surface of the other end of the limiting pin body (902) is provided with an auxiliary ball (905); and the auxiliary ball (905) is provided with cleaning bristles (906).

10. The low-pressure injection molding device for automobile interior decoration parts according to claim 6, characterized in that: The limiting pin body (902) is placed in the limiting sleeve (901), and one limiting pin body (902) is placed in one limiting sleeve (901); the auxiliary sphere (905) at the end of the limiting pin body (902) and the auxiliary circular hole (807) on the cover (805) are arranged at corresponding positions and have the same number of groups.

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