Forging and pressing die for high-precision alloy mobile phone frame

Abstract

The utility model relates to the technical field of metal processing, and discloses a forging and pressing die for a high-precision alloy mobile phone frame, which comprises a bottom plate, the top of the bottom plate is fixedly connected with a base station, a positioning hole is arranged in an upper die, telescopic rods are arranged on two sides of the inner wall of the positioning hole, and springs are sleeved on the outer walls of the telescopic rods. The other end of the telescopic rod is fixedly connected with a wedge-shaped block, an electric pusher is fixedly connected into the base table, the output end of the electric pusher is fixedly connected with a push rod, the outer wall of the push rod is fixedly connected with a limiting block, the top of the push rod is fixedly connected with a positioning ball, and the outer wall of the push rod is slidably connected with a dish-shaped block. According to the utility model, the lower pressing block moves to the groove of the base station, the positioning ball enters the hole to extrude the wedge block, the telescopic rod and the spring act and then are locked, and the electric pusher operates after forging and pressing to enable the dish block to enable the wedge block to retract and unlock, so that accurate positioning is realized, the positioning problem of a traditional die is solved, the production precision is improved, the rejection rate is reduced, and the production efficiency is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to metal processing technical field especially relates to a high accuracy alloy mobile phone frame's forging and pressing die. BACKGROUND

[0002] In the modern electronic equipment manufacturing field, as people's daily life indispensable communication and entertainment tool, its appearance and quality are concerned, with the continuous progress of science and technology, the requirement of consumer to mobile phone frame is higher and higher, not only pursue beautiful, pay more attention to its precision and quality, high accuracy alloy mobile phone frame's forging and pressing die arises at the historic moment, in the production process of mobile phone frame, forging and pressing die plays the key role, it directly decides the shape, size precision and mechanical property of mobile phone frame, with the increasingly fierce competition of mobile phone market, improving production efficiency and product quality become the core target of enterprise, therefore the research and improvement of high accuracy alloy mobile phone frame's forging and pressing die have important significance.

[0003] In the prior art, mobile phone frame forging and pressing die generally adopts the traditional structure design, generally is composed of upper die and lower die, is fixed on the forging and pressing equipment through bolt or other connecting mode, in the positioning aspect, preliminary positioning is carried out through simple guide column or positioning pin, but the positioning mode precision is limited, only relies on the accuracy of equipment itself to ensure the alignment of upper and lower dies in the opening and closing process of die, lacks effective locking and accurate positioning mechanism, in the installation and disassembly of die, generally adopts conventional bolt fastening mode, this mode needs to use tools to tighten or loosen the bolt one by one in the operation process, not only time-consuming and laborious, but also easy to appear bolt loose or over-tightening, influence the installation precision and stability of die.

[0004] The current mobile phone frame forging and pressing die has the problem of poor positioning accuracy, in the traditional die, due to the simple positioning structure and lack of effective locking mechanism, the upper and lower dies are prone to relative displacement during forging and pressing due to factors such as equipment vibration and pressure impact, which may cause the mobile phone frame to be unable to accurately form during forging and pressing, resulting in size deviation, for example, when producing narrow frame mobile phones, the width size of the frame is required to be extremely high, and any deviation will affect the installation of the mobile phone screen and the overall appearance, and unstable positioning will also cause poor consistency of the product, increase the scrap rate, increase the production cost, and also reduce the production efficiency, which cannot meet the demand of large-scale high-quality production, therefore, a high-precision alloy mobile phone frame forging and pressing die is proposed to solve the above problems. UTILITY MODEL CONTENTS

[0005] In order to make up for the above shortcomings, the utility model provides a high-precision alloy mobile phone frame forging and pressing die, which aims to improve the problems of inaccurate die positioning, poor stability, large product size deviation and low production efficiency in the prior art.

[0006] In order to achieve the above object, the utility model adopts the following technical scheme:

[0007] A high-precision alloy mobile phone frame forging die, including the bottom plate, the bottom plate top fixedly connected with the abutment, a plurality of support columns are fixedly connected on the upper surface of the abutment, the support column top fixedly connected with the top plate, the top plate top is provided with forging assembly, the forging assembly is used to lower the die and carry out forging to material, the die assembly is arranged between the abutment and the top plate, and the die assembly is used to help the mobile phone frame forging forming;

[0008] The die assembly includes a lower pressing block, the lower pressing block is slidably connected inside the abutement, an upper die is slidably connected inside the lower pressing block, a lower die is slidably connected inside the abutment, a positioning hole is formed in the upper die, telescopic rods are arranged on the inner wall of the positioning hole on both sides, springs are sleeved on the outer wall of the telescopic rods, one end of the telescopic rods is fixedly connected inside the lower pressing block, the other end of the telescopic rods is fixedly connected with a wedge-shaped block, an electric pusher is fixedly connected inside the abutment, a push rod is fixedly connected to the output end of the electric pusher, a limiting block is fixedly connected to the outer wall of the push rod, a positioning ball is fixedly connected to the top of the push rod, a disc-shaped block is slidably connected to the outer wall of the push rod, and the disc-shaped block is located between the limiting block and the positioning ball.

[0009] As a further description of the above technical scheme:

[0010] The forging assembly includes a hydraulic device, the hydraulic device is fixedly connected to the top of the top plate, a hydraulic rod is fixedly connected to the output end of the hydraulic device, and the hydraulic rod is fixedly connected to the top of the lower pressing block.

[0011] As a further description of the above technical scheme:

[0012] The inside of the top plate is slidably connected with an auxiliary rod, and the auxiliary rod is distributed on the left and right sides of the hydraulic device.

[0013] As a further description of the above technical scheme:

[0014] A plurality of mounting holes are formed in the both sides of the bottom plate, and the mounting holes are distributed on the left and right sides of the abutment.

[0015] As a further description of the above technical scheme:

[0016] A plurality of locking columns are slidably connected inside the upper die and the lower die, and the locking columns are also slidably connected inside the abutment and the lower pressing block.

[0017] As a further description of the above technical scheme:

[0018] The locking hole is located at the bottom of the locking column;

[0019] As a further description of the above technical solution:

[0020] The inner wall of the locking column is slidably connected with a threaded column, and a plurality of rolling balls are slidably connected in the locking column.

[0021] As a further description of the above technical solution:

[0022] The bottom of the threaded column is fixedly connected with a movable ball, and the bottom of the inner wall of the locking column is fixedly connected with a limiting column.

[0023] The utility model has the following beneficial effects:

[0024] 1、The utility model discloses a lower pressing block is displaced to the recess of the base, and the positioning ball enters the positioning hole, and the wedge-shaped block is pressed in and moves inwards to the top, drives the telescopic rod to contract, and the spring is compressed, and when the positioning ball is to the most inside, the wedge-shaped block bounces back and locks, after forging and pressing are completed, the electric pusher pushes the push rod, the limiting block and the disc-shaped block and moves up, the disc-shaped block is to the both sides of the wedge-shaped block and makes it retract, continues to move up to the bottom of the positioning ball and then the electric pusher retreats, drives the positioning ball to unlock, realizes accurate positioning, solves the problem that the traditional mould positioning is not accurate, and the stability is poor and leads to the product size deviation, and the production efficiency is low, improves the production precision and quality of mobile phone frame, and reduces the scrap rate.

[0025] 2、The utility model discloses a staff uses screwdriver to rotate the threaded column and makes it rotate displacement upwards, and the movable ball rises along, and the rolling ball in the locking column is loose and retreats to the column under the loss of extrusion force and keeps stable under the action of the limiting column, and the upper and lower moulds are unlocked, when installing, the threaded column is tightened and drives the movable ball to move down and extrudes the rolling ball to the locking hole and can be locked, solves the problem that the previous mould is difficult to disassemble and install, and the time is long, and the equipment maintenance efficiency and production progress are influenced, improves the convenience and production efficiency of overhaul and maintenance. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A three-dimensional schematic view of a high-precision alloy mobile phone frame forging and pressing die is provided for the utility model;

[0027] Figure 2 A structure schematic view of the upper mould of the high-precision alloy mobile phone frame forging and pressing die is provided for the utility model;

[0028] Figure 3 A structure schematic view of the lower mould of the high-precision alloy mobile phone frame forging and pressing die is provided for the utility model;

[0029] Figure 4The utility model provides a kind of high-precision alloy mobile phone frame's structure diagram of positioning hole of forging and pressing die of the utility model proposes;

[0030] Figure 5 For Figure 4 Enlarged view at A.

[0031] Figure 6 The utility model provides a kind of high-precision alloy mobile phone frame's structure diagram of locking column of forging and pressing die of the utility model proposes;

[0032] Figure 7 For Figure 6 Enlarged view at B.

[0033] Legend:

[0034] 1, bottom plate;2, base;3, support column;4, top plate;5, hydraulic device;6, hydraulic rod;7, auxiliary rod;8, mounting hole;9, lower pressing block;10, upper die;11, lower die;12, positioning hole;13, telescopic rod;14, spring;15, wedge block;16, electric pusher;17, push rod;18, limit block;19, disc-shaped block;20, positioning ball;21, locking column;22, threaded column;23, movable ball;24, ball;25, locking hole;26, limit column. Specific embodiments

[0035] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the utility model.

[0036] Refer to Figure 1 - Figure 5The utility model provides a kind of high-precision alloy mobile phone frame's forging die, including bottom plate 1, bottom plate 1 top is fixedly connected with abutment 2, abutment 2 flatness is high, can provide stable support for mould assembly, a plurality of support columns 3 are fixedly connected on abutment 2 upper surface, support column 3 top is fixedly connected with top plate 4, top plate 4 top is provided with forging assembly, forging assembly is used to press down mould to carry out forging to material, mould assembly is used to assist power mobile phone frame forging forming, mould assembly includes down block 9, down block 9 is made of aluminium alloy, aluminium alloy is light in weight and higher in strength, can reduce overall weight while guaranteeing structural strength, reduce the load of hydraulic system, down block 9 is slidably connected in abutment 2 interior, upper die 10 is slidably connected in down block 9 interior, lower die 11 is slidably connected in abutment 2 interior, upper die 10 and lower die 11 are made of high-strength alloy steel material, steel material is subjected to special heat treatment process, so it has higher hardness and wear resistance, can withstand huge pressure and friction force in forging process, guarantee the service life of mould, upper die 10 is provided with positioning hole 12 inside, both sides of the inner wall of positioning hole 12 are provided with telescopic rod 13, spring 14 is sleeved on the outer wall of telescopic rod 13, spring 14 has good elastic property, can provide stable elastic force in compression and rebound process, one end of telescopic rod 13 is fixedly connected in down block 9 interior, the other end of telescopic rod 13 is fixedly connected with wedge block 15, wedge block 15 is wedge-shaped, and surface is smooth, abutment 2 interior is fixedly connected with electric pusher 16, the output of electric pusher 16 is fixedly connected with push rod 17, the surface of the rod body of push rod 17 is treated smooth and coated with lubricant, reduces the friction resistance between disc-shaped block 19 and other components, limit block 18 is fixedly connected on the outer wall of push rod 17, push rod 17 top is fixedly connected with positioning ball 20, positioning ball 20 is made of high-hardness ceramic material, ceramic material has the advantages of high hardness, wear resistance, corrosion resistance, can maintain good shape and performance in frequent positioning and friction process, push rod 17 outer wall is slidably connected with disc-shaped block 19, the surface of disc-shaped block 19 is subjected to special treatment, has lower friction coefficient, can smoothly slide when contacting with wedge block 15, disc-shaped block 19 is located between limit block 18 and positioning ball 20, forging assembly includes hydraulic ware 5, hydraulic ware 5 as the core component of providing forging pressure, can withstand the force generated by high-pressure liquid without deforming, can stably move under the push of hydraulic oil, ensure that good performance is maintained under high pressure and frequent working conditions, hydraulic ware 5 bottom is fixedly connected in top plate 4 top, hydraulic rod 6 is fixedly connected in the output of hydraulic ware 5, hydraulic rod 6 is made of solid carbon steel, the surface of hydraulic rod 6 is subjected to chrome plating treatment, corrosion in long-term use process, hydraulic rod 6 bottom is fixedly connected in down block 9 top, auxiliary rod 7 is slidably connected in top plate 4 interior, the surface of auxiliary rod 7 is smooth, and it is closely matched with the slide hole on top plate 4, auxiliary rod 7 plays the role of guiding and stabilizing down block 9 in sliding process,Ensure that the lower block 9 can move vertically downward, improve the forging precision, auxiliary rod 7 is distributed in the hydraulic device 5 left and right two sides, the bottom plate 1 both sides are provided with a plurality of mounting holes 8, mounting hole 8 is used for fixing the mold on the workbench, the inner wall of mounting hole 8 is treated by tapping, can be closely matched with bolt, ensure that the mold will not be displaced in the working process, mounting hole 8 is distributed in the base 2 left and right sides,

[0037] Specifically, when using the mobile phone frame forging die, start the hydraulic device 5, the hydraulic device 5 pushes the hydraulic rod 6 to displace downward, the displacement of the hydraulic rod 6 drives the lower block 9 to displace downward synchronously, and the displacement of the lower block 9 also drives the displacement of the two side auxiliary rods 7, and the displacement of the lower block 9 also drives the downward displacement of the upper die 10 in the lower block 9, when the lower block 9 is positioned in the internal groove of the base 2, the positioning ball 20 will enter the inner wall of the positioning hole 12, when the positioning ball 20 is on the two sides of the wedge block 15 in the inner wall of the positioning hole 12, the two sides of the wedge block 15 are subjected to lateral extrusion force and thus displace inward, the displacement of the wedge block 15 drives the contraction of the telescopic rod 13 and the compression of the spring 14, when the positioning ball 20 continues to displace to the innermost part of the positioning hole 12, the wedge block 15 loses the lateral extrusion force, the telescopic rod 13 and the spring 14 rebound, thereby completing the locking of the positioning ball 20, when the forging is completed, the electric pusher 16 pushes the push rod 17 to displace upward, the push rod 17 drives the displacement of the limiting block 18, the limiting block 18 is made of cast iron and has high strength and stability, which can limit the movement range of the disc-shaped block 19. At the same time, the disc-shaped block 19 is also displaced upward under the driving of the limiting block 18, when the disc-shaped block 19 is displaced to the two sides of the wedge block 15, the wedge block 15 retracts, the disc-shaped block 19 continues to displace to the bottom of the positioning ball 20, at this time, the electric pusher 16 retreats and drives the positioning ball 20 and the disc-shaped block 19 to displace downward, at this time, the wedge block 15 retracts again under the extrusion of the disc-shaped block 19, thereby driving the positioning ball 20 to be positioned outside the positioning hole 12, thereby completing the unlocking of the positioning ball 20. Through such accurate positioning and unlocking mechanism, the effect of rapid and accurate positioning is realized, and the precision and quality of the mobile phone frame forging are improved.

[0038] Reference Figure 6 - Figure 7A plurality of locking columns 21 are slidably connected inside the upper die 10 and the lower die 11, and are also slidably connected inside the base 2 and the pressing block 9. The base 2 and the pressing block 9 are provided with locking holes 25 at the bottom of the locking columns 21. A threaded column 22 is slidably connected to the inner wall of the locking column 21. The threaded column 22 is made of stainless steel, and the threads on the surface thereof are finely processed to tightly cooperate with the inner wall of the locking column 21, so that the rotational movement can be effectively converted into axial displacement movement during rotation. A plurality of balls 24 are slidably connected inside the locking column 21. The balls 24 are made of bearing steel and are subjected to quenching treatment on the surface, so that the hardness is high and the smoothness is good. The balls 24 are circumferentially distributed inside the locking column 21. The spacing between each ball 24 is appropriate, which can ensure sufficient space to roll outward during extrusion, and can also provide uniform support force during locking. The bottom of the threaded column 22 is fixedly connected with a movable ball 23. The surface of the movable ball 23 is smooth and spherical, which can uniformly contact and apply pressure to the balls 24. The inner wall of the locking column 21 is fixedly connected with a limiting column 26 at the bottom. The limiting column 26 is distributed below the balls 24, which can block the balls 24 from falling excessively, and ensure that the balls 24 can be accurately extruded into the locking holes 25 when locking is required.

[0039] Specifically, when the mold needs to be disassembled for daily maintenance and repair of the equipment, the worker first prepares a suitable screwdriver tool. The worker inserts the screwdriver into the hole corresponding to the threaded column 22, rotates the screwdriver to drive the threaded column 22 to rotate, and under the action of the thread, the threaded column 22 gradually moves upward. The displacement of the threaded column 22 drives the upward displacement of the movable ball 23. With the displacement of the movable ball 23, the rolling ball 24 on the inner wall of the locking column 21 loses the extrusion force and becomes loose. When the movable ball 23 is displaced upward, the lateral pressure on the rolling ball 24 decreases, and the rolling ball 24 retreats into the locking column 21. At the same time, under the limitation of the limiting column 26, the rolling ball 24 will not roll randomly. In this way, the upper mold 10 and the lower mold 11 are unlocked. When installing, only the threaded column 22 needs to be tightened to drive the movable ball 23 to displace downward and extrude the rolling ball 24 into the locking hole 25. When the threaded column 22 rotates downward, the movable ball 23 moves downward with the movement of the threaded column 22. The movable ball 23 gradually extrudes the rolling ball 24, and the rolling ball 24 rolls to the outside of the locking column 21. Since the hole diameter of the locking hole 25 is slightly smaller than the diameter of the rolling ball 24, when the rolling ball 24 is extruded into the locking hole 25, the rolling ball 24 is in close contact with the inner wall of the locking hole 25, generating strong friction and clamping force, thereby achieving the locking of the upper mold 10 and the lower mold 11. The sliding fit between the locking column 21 and the upper mold 10, the lower mold 11, the base 2 and the pressing block 9 is precisely machined, and the gap is small, which can ensure that the locking column 21 can smoothly slide during installation and disassembly, and at the same time can ensure the stability of the mold in the locked state. Through such an operation mode, the effect of quickly installing and disassembling the upper mold 10 and the lower mold 11 is achieved, the efficiency of equipment maintenance and repair is improved, the operation difficulty is reduced, and the production of alloy mobile phone frames is facilitated.

[0040] Working principle: when using the forging die of the mobile phone frame, first, the hydraulic rod 6 is pushed downward by the hydraulic device 5, the displacement of the hydraulic rod 6 drives the downward displacement of the lower pressing block 9, and the displacement of the lower pressing block 9 also drives the displacement of the auxiliary rods 7 on both sides of the lower pressing block 9, and the displacement of the lower pressing block 9 also drives the downward displacement of the upper die 10 in the lower pressing block 9, when the lower pressing block 9 is positioned in the internal groove of the base 2, the positioning ball 20 enters the inner wall of the positioning hole 12, when the positioning ball 20 reaches the wedge-shaped blocks 15 on both sides of the inner wall of the positioning hole 12, the wedge-shaped blocks 15 are subjected to lateral extrusion force and are displaced inward, the displacement of the wedge-shaped blocks 15 drives the contraction of the telescopic rod 13 and the compression of the spring 14, when the positioning ball 20 continues to displace to the innermost part of the positioning hole 12, the wedge-shaped blocks 15 lose the lateral extrusion force, the telescopic rod 13 and the spring 14 rebound, thereby completing the locking of the positioning ball 20, after the forging is completed, the push rod 17 is pushed upward by the electric pusher 16, the push rod 17 drives the displacement of the limiting block 18, and the disc-shaped block 19 is also displaced upward under the driving of the limiting block 18, when the disc-shaped block 19 is displaced to the both sides of the wedge-shaped blocks 15, the wedge-shaped blocks 15 retract, the disc-shaped block 19 continues to displace to the bottom of the positioning ball 20, at this time, the electric pusher 16 retreats and drives the downward displacement of the positioning ball 20 and the disc-shaped block 19, at this time, the wedge-shaped blocks 15 retract again under the extrusion of the disc-shaped block 19, thereby driving the positioning ball 20 to be positioned outside the positioning hole 12, thereby completing the unlocking of the positioning ball 20, thereby realizing the effect of quick and accurate positioning, when the equipment needs to be disassembled for daily maintenance, the worker first uses a screwdriver to extend into the hole corresponding to the threaded column 22, rotates the screwdriver to drive the threaded column 22 to rotate, under the action of the thread, the threaded column 22 gradually moves upward, the displacement of the threaded column 22 drives the upward displacement of the movable ball 23, as the movable ball 23 displaces, the rolling balls 24 on the inner wall of the locking column 21 lose the extrusion force and become loose, thereby retreating into the locking column 21, at the same time, under the limitation of the limiting column 26, the rolling balls 24 will not roll randomly, thereby completing the unlocking of the upper die 10 and the lower die 11, when installing, the threaded column 22 is only needed to be tightened to drive the movable ball 23 to displace downward and extrude the rolling balls 24 into the locking hole 25, thereby completing the locking of the upper die 10 and the lower die 11, thereby realizing the effect of quick installation and disassembly of the upper die 10 and the lower die 11.

[0041] Finally, it should be pointed out that: the above only describes the preferred embodiments of the present application and is not intended to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacement for some of the technical features, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A high-precision alloy mobile phone frame forging die, comprising a bottom plate (1), characterized in that: The base plate (1) is fixedly connected to the top of the base platform (2), and multiple support columns (3) are fixedly connected to the upper surface of the base platform (2). The top plate (4) is fixedly connected to the top of the support columns (3). A forging assembly is provided on the top of the top plate (4). The forging assembly is used to press the material with a lower die. A die assembly is provided between the base platform (2) and the top plate (4). The die assembly is used to assist in the forging and forming of the mobile phone frame. The mold assembly includes a lower pressing block (9), which is slidably connected inside the base (2). An upper mold (10) is slidably connected inside the lower pressing block (9), and a lower mold (11) is slidably connected inside the base (2). A positioning hole (12) is provided inside the upper mold (10). Telescopic rods (13) are provided on both sides of the inner wall of the positioning hole (12). A spring (14) is sleeved on the outer wall of the telescopic rod (13). One end of the telescopic rod (13) is fixedly connected to the lower pressing block (9). Inside the base (2), a wedge block (15) is fixedly connected to the other end of the telescopic rod (13). An electric actuator (16) is fixedly connected inside the base (2). A push rod (17) is fixedly connected to the output end of the electric actuator (16). A limit block (18) is fixedly connected to the outer wall of the push rod (17). A positioning ball (20) is fixedly connected to the top of the push rod (17). A disc block (19) is slidably connected to the outer wall of the push rod (17). The disc block (19) is located between the limit block (18) and the positioning ball (20).

2. The high-precision alloy mobile phone frame forging die according to claim 1, characterized in that: The forging assembly includes a hydraulic press (5), the bottom of which is fixedly connected to the top of the top plate (4), and a hydraulic rod (6) is fixedly connected to the output end of the hydraulic press (5), the bottom of which is fixedly connected to the top of the lower pressing block (9).

3. The high-precision alloy mobile phone frame forging die according to claim 2, characterized in that: An auxiliary rod (7) is slidably connected inside the top plate (4), and the auxiliary rod (7) is distributed on the left and right sides of the hydraulic device (5).

4. The high-precision alloy mobile phone frame forging die according to claim 1, characterized in that: Multiple mounting holes (8) are provided on both sides of the base plate (1), and the mounting holes (8) are distributed on the left and right sides of the base (2).

5. The high-precision alloy mobile phone frame forging die according to claim 1, characterized in that: Both the upper mold (10) and the lower mold (11) are slidably connected to a plurality of locking posts (21), which are also slidably connected inside the base (2) and the lower pressure block (9).

6. The high-precision alloy mobile phone frame forging die according to claim 5, characterized in that: The base (2) and the lower pressure block (9) are provided with locking holes (25), which are located at the bottom of the locking post (21).

7. The high-precision alloy mobile phone frame forging die according to claim 5, characterized in that: The inner wall of the locking post (21) is slidably connected to a threaded post (22), and a plurality of balls (24) are slidably connected inside the locking post (21). The balls (24) are distributed in a circumferential shape inside the locking post (21).

8. The high-precision alloy mobile phone frame forging die according to claim 7, characterized in that: The bottom of the threaded post (22) is fixedly connected to a movable ball (23), and the bottom of the inner wall of the locking post (21) is fixedly connected to a limit post (26).

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