A magnesium alloy vehicle frame die casting molding device

Abstract

This invention discloses a magnesium alloy vehicle frame die-casting molding apparatus, belonging to the technical field of die-casting equipment. It includes a machine base, on which a base platform and a fixed mold are fixedly mounted. An injection chamber is fixedly mounted on the base platform, and a cavity is formed on the fixed mold. The advantages are: This apparatus addresses the problem that traditional venting channels only reach the edge of the cavity, are difficult to access deep cavities, and are located in corners. Through a linkage design between the external venting needle and the guide tube, the external venting needle can penetrate deep into the corners and move dynamically with the injection action, venting residual gas in the corners and avoiding defects such as porosity and shrinkage, thus ensuring the strength of the vehicle frame. Simultaneously, addressing the problem of low venting efficiency and easy backflow clogging with fixed-diameter venting, the eccentric fine hole of the internal venting needle rotates synchronously with the injection, changing its diameter. This allows for large-scale venting in the initial stage and prevention of clogging in the later stage, eliminating the need for frequent machine shutdowns for cleaning. Mechanical transmission allows the venting position and diameter to adapt to changes in cavity pressure and gas volume in real time, matching the filling rhythm and significantly improving die-casting quality and production stability.

Description

Technical Field

[0001] This invention relates to the field of die-casting equipment technology, and in particular to a die-casting molding apparatus for magnesium alloy vehicle frames. Background Technology

[0002] Magnesium alloys are increasingly used in the automotive frame manufacturing industry due to their advantages such as low density, high specific strength, and good shock resistance. Die casting has become the mainstream forming method for magnesium alloy frames because of its high production efficiency and good forming accuracy. However, the gas venting effect inside the mold cavity during magnesium alloy die casting directly affects the quality of the casting.

[0003] The existing venting structure of magnesium alloy frame die-casting equipment has significant shortcomings: First, traditional venting channels or fixed venting pins are mostly located at the edge of the mold cavity, making it difficult to reach deep cavities, corners, and other dead areas of the frame mold cavity. This results in the inability to completely expel air, water vapor, and oxidizing gases generated during the die-casting process, making the castings prone to defects such as porosity, shrinkage cavities, and cold shuts, seriously affecting the structural strength and service life of the frame. Second, the diameter of the venting channels is mostly fixed. In the early stages of die casting, when a large amount of gas needs to be quickly expelled from the mold cavity, the fixed small diameter is not efficient enough. In the later stages of die casting, after the molten metal is filled in, the fixed large diameter can easily cause molten metal to backflow and oxide slag to enter the venting channel, causing blockage of the venting channel. The venting effect of subsequent castings drops sharply, requiring frequent shutdowns for cleaning and reducing production efficiency. Third, the existing venting structure lacks coordination with the injection filling process. It cannot adjust the venting state according to the dynamic changes in internal pressure and gas volume, resulting in a mismatch between the venting and filling rhythms, further exacerbating the risk of casting defects. Summary of the Invention

[0004] The purpose of this invention is to solve the problems in the background art, and to propose a magnesium alloy vehicle frame die casting molding device.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A magnesium alloy vehicle frame die casting molding apparatus includes a machine base, on which a base platform and a fixed mold are fixedly disposed. An injection chamber is fixedly disposed on the base platform, and a cavity is formed on the fixed mold.

[0007] A gas discharge structure is provided between the injection chamber and the fixed mold. During die casting, the pressure and gas volume inside the cavity change dynamically with the filling process of the molten metal. The gas discharge structure is used to reach into dead corners and discharge residual gas. With the coordinated action of movement and diameter change, it adapts to the venting requirements at different stages and is used to reduce porosity, shrinkage, and cold shut caused by gas accumulation in the casting.

[0008] In the aforementioned magnesium alloy vehicle frame die casting molding device, the machine base is provided with a mold opening and closing mechanism, the mold opening and closing mechanism is provided with a moving mold, and the moving mold is slidably disposed relative to the fixed mold, and the moving mold is also provided with a cavity, the two cavities cooperating with each other.

[0009] In the aforementioned magnesium alloy vehicle frame die-casting molding device, piston one and piston two are slidably and sealed within the injection chamber, and a connecting rod is fixedly installed between piston one and piston two.

[0010] In the above-mentioned magnesium alloy frame die casting molding device, an inner piston is fixedly provided on one side of the piston two, and an outer injection rod is fixedly connected between the fixed mold and the injection chamber, and the inner piston slides in a sealed manner within the outer injection rod.

[0011] In the aforementioned magnesium alloy vehicle frame die-casting molding apparatus, a conduit is sealed and slides within the injection chamber, and an external venting needle is sealed and slides within the fixed mold.

[0012] In the aforementioned magnesium alloy frame die-casting molding device, the gas discharge structure includes a gear rod 1 fixedly mounted on a connecting rod, two positioning plates fixed in the injection chamber, a short shaft fixedly mounted between the two positioning plates, a gear rotatably mounted on the short shaft, a displacement groove opened on the injection chamber, and a gear rod 2 fixedly mounted at one end of the guide tube, wherein the gear meshes with both the gear rod 1 and the gear rod 2, and the gear rod 2 slides within the displacement groove.

[0013] In the aforementioned magnesium alloy vehicle frame die-casting molding device, a rotating rod is fixedly installed on one side of the connecting rod, and a guide rod is fixedly installed at the lower end of the rotating rod.

[0014] In the above-mentioned magnesium alloy frame die-casting molding device, an inner venting needle is rotatably arranged inside the outer venting needle. One end of the inner venting needle is provided with a fine hole, which is eccentrically arranged. Both the injection chamber and the guide tube are provided with venting grooves, which provide ventilation space for the inner venting needle.

[0015] In the aforementioned magnesium alloy frame die-casting molding device, both the guide tube and the injection chamber are provided with grooves, and the guide rod slides within the grooves for use.

[0016] In the aforementioned magnesium alloy frame die-casting molding device, a connecting shaft is fixedly provided at one end of the internal exhaust pin, and a rotating sleeve is fixedly provided on the outside of the connecting shaft. The rotating sleeve rotates within the guide tube. A guide groove is provided at one end of the connecting shaft, and the guide rod slides within the guide groove.

[0017] Compared with existing technologies, the advantages of this invention are as follows: This device addresses the problem that traditional venting channels are only located at the edge of the mold cavity, inaccessible deep cavities, and dead corners. Through the linkage design of the external venting needle and the guide tube, the external venting needle can penetrate deep into dead corners and move dynamically with the injection action to expel residual gas in the dead corners, avoiding defects such as porosity and shrinkage, and ensuring the strength of the frame. At the same time, it addresses the problem of low venting efficiency and easy backflow and blockage of fixed-diameter venting. The eccentric fine hole of the internal venting needle rotates and changes diameter synchronously with the injection, resulting in large venting in the initial stage and anti-blocking in the later stage. It eliminates the need for frequent machine stops for cleaning. Through mechanical transmission, the venting position and diameter are adapted to the changes in mold cavity pressure and gas volume in real time, matching the filling rhythm, which significantly improves the die casting quality and production stability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a magnesium alloy vehicle frame die-casting molding device proposed in this invention;

[0019] Figure 2 This is a top view of the present invention;

[0020] Figure 3 For the present invention Figure 2 Cross-sectional view of the medium-pressure injection chamber along the AA direction;

[0021] Figure 4 For the present invention Figure 3 Enlarged structural diagram of part a;

[0022] Figure 5 In this invention Figure 2 Cross-sectional view of the central conduit along the AA direction;

[0023] Figure 6 This is a schematic diagram of the internal exhaust needle in this invention;

[0024] Figure 7 For the present invention Figure 5 A magnified schematic diagram of part b in the middle.

[0025] In the diagram: 1. Base; 2. Injection chamber; 3. External injection rod; 4. Guide tube; 5. Fixed mold; 6. Moving mold; 7. Mold opening and closing mechanism; 8. Base platform; 9. Piston 1; 10. Connecting rod; 11. Piston 2; 12. Inner piston; 13. Coupling shaft; 14. External venting pin; 15. Rotating sleeve; 16. Venting groove; 17. Inner venting pin; 18. Guide groove; 19. Sliding groove; 20. Rotating rod; 21. Gear rack 1; 22. Gear rack 2; 23. Gear; 24. Positioning plate; 25. Guide rod; 26. Cavity. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Reference Figure 1 A magnesium alloy vehicle frame die casting molding device includes a base 1, which is a basic load-bearing structure. Its core function is to provide a stable and solid installation reference for all components of the entire device, ensuring that the movement of each mechanism is precise and without displacement deviation during the die casting process. The base 1 is integrally formed from high-strength cast iron to ensure sufficient structural rigidity to withstand the high pressure impact during die casting.

[0028] A base platform 8 and a fixed mold 5 are fixedly mounted on the base 1. An injection chamber 2 is fixedly mounted on the base platform 8. The base platform 8 is specifically used to fix the injection chamber 2. The base platform 8 and the injection chamber 2 are fixedly connected by welding to prevent vibration or displacement of the injection chamber 2 during the injection process. An accumulator is installed on the fixed injection chamber 2. The accumulator stores hydraulic energy in advance during the injection stage (before injection). When injection is started, the accumulator can release a large amount of high-pressure oil instantly, pushing the piston 9 and piston 11 in the injection chamber 2 to move rapidly, ensuring that the molten metal is injected into the cavity 26 with sufficient pressure and speed, avoiding filling defects.

[0029] A cavity 26 is formed on the fixed mold 5. An opening and closing mold mechanism 7 is installed on the machine base 1, located on one side of the machine base 1 (existing technology). This mechanism is hydraulically driven, and its core function is to control the sliding of the moving mold 6 relative to the fixed mold 5 in the horizontal direction, achieving mold closing and sealing, and mold opening and part removal. The hydraulic system of the opening and closing mold mechanism 7 is equipped with a pressure sensor to monitor the mold closing force in real time, ensuring reliable sealing of the cavity 26 during mold closing and preventing molten metal leakage during die casting. The opening and closing mold mechanism 7 has a moving mold 6, which slides relative to the fixed mold 5. The moving mold 6 also has a cavity 26. The two cavities 26 work together to form the forming space of the magnesium alloy frame, i.e., the cavity 26. The inner walls of the cavities 26 of both the fixed mold 5 and the moving mold 6 are polished to ensure the surface accuracy of the formed casting. The contours of the two cavities 26 are perfectly matched to the design dimensions of the magnesium alloy frame, forming a sealed forming cavity after mold closing.

[0030] Reference Figures 1-3The injection chamber 2 is sealed and slidingly equipped with piston 9 and piston 11. A connecting rod 10, made of high-strength alloy steel, is fixedly installed between pistons 9 and 11 to ensure synchronous movement. Piston 9 and the inner wall of the injection chamber 2 are sealed with a gap seal structure and a high-temperature resistant sealing ring to ensure smooth sliding and prevent molten metal leakage. An inner piston 12 is fixedly installed on one side of piston 11. An outer injection rod 3 is fixedly connected between the fixed mold 5 and the injection chamber 2, and the inner piston 12 slides within the outer injection rod 3. A grouting groove (not shown in the figure, located on the outer injection rod 3) is provided on the outer injection rod 3. Figure 3 The molten metal liquid is poured into the trough on the outer injection rod 3 from the left side of the inner piston 12. Under the action of the accumulator, the piston 9 and piston 11 in the injection chamber 2 are pushed to move quickly. At this time, the inner piston 12 quickly injects material into the cavity 26 to realize the die casting of the magnesium alloy frame.

[0031] Reference Figures 1-7 The injection chamber 2 has a sealed sliding guide tube 4 made of high-temperature resistant alloy material, and the fixed mold 5 has a sealed sliding external venting pin 14. A gas discharge structure is provided between the injection chamber 2 and the fixed mold 5. During die casting, the internal pressure and gas volume of the cavity 26 change dynamically with the filling process of the molten metal. The gas discharge structure is used to reach into dead corners and discharge residual gas. With the coordinated action of movement and diameter change, it adapts to the venting requirements at different stages, which is used to reduce porosity, shrinkage porosity and cold shut caused by gas accumulation in the casting.

[0032] The gas discharge structure includes a gear 21 fixedly mounted on the connecting rod 10, two positioning plates 24 fixed inside the injection chamber 2, a short shaft fixedly mounted between the two positioning plates 24, a gear 23 rotatably mounted on the short shaft, a displacement groove on the injection chamber 2, a gear 22 fixedly mounted at one end of the guide tube 4, and the gear 23 meshes with both the gear 21 and the gear 22, with the gear 22 sliding in the displacement groove. The gear 23 meshes with both the gear 21 and the gear 22 to form a transmission mechanism. Its core function is to convert the linear motion of the connecting rod 10 into the linear motion of the guide tube 4, realizing the synchronous linkage between the guide tube 4 and the piston, thereby driving the external exhaust needle 14 to move.

[0033] A rotating rod 20 is fixedly installed on one side of the connecting rod 10, and a guide rod 25 is fixedly installed at the lower end of the rotating rod 20. An inner exhaust needle 17 is rotatably installed inside the outer exhaust needle 14. One end of the inner exhaust needle 17 has a small hole, which is eccentrically positioned. Both the injection chamber 2 and the conduit 4 have exhaust grooves 16, which provide ventilation space for the inner exhaust needle 17. Both the conduit 4 and the injection chamber 2 have sliding grooves 19, and the guide rod 25 slides within the sliding grooves 19. One end of the inner exhaust needle 17 is fixedly installed with a connecting shaft 13, and a rotating sleeve 15 is fixedly installed on the outside of the connecting shaft 13. The rotating sleeve 15 rotates within the conduit 4. One end of the connecting shaft 13 has a guide groove 18, and the guide rod 25 slides within the guide groove 18. The rotating rod 20 is vertically fixed to one side of the connecting rod 10. The guide rod 25 welded to its lower end adopts a cylindrical structure. The guide rod 25 slides through the guide tube 4, the slide groove 19 opened in the injection chamber 2, and the guide groove 18 at one end of the connecting shaft 13. The slide groove 19 provides a movement trajectory limit for the guide rod 25, ensuring that the guide rod 25 slides in a preset direction. The guide groove 18 is opened at the end of the connecting shaft 13 and has a spiral structure. When the guide rod 25 moves linearly along the slide groove 19, the spiral guide groove 18 converts the linear motion into the circumferential rotation of the connecting shaft 13, realizing the rotational diameter change of the internal exhaust needle 17.

[0034] One end of the internal venting pin 17 extends into the dead corner area of ​​the cavity 26, and the other end is fixedly connected to the connecting shaft 13. The venting end of the internal venting pin 17 has an eccentric fine hole. The eccentric design of the fine hole is the key to achieving the gradual change of the hole diameter. The internal venting pin 17 is made of high temperature resistant and wear-resistant alloy material and the surface is nitrided to improve its service life. The rotating sleeve 15 fixed on the outside of the connecting shaft 13 is rotatably installed inside the guide tube 4. The rotating sleeve 15 adopts a sliding bearing structure to reduce the friction when the connecting shaft 13 rotates, and at the same time plays a radial positioning role for the connecting shaft 13, ensuring the precise movement of the internal venting pin 17 and avoiding collision with the inner wall of the cavity 26.

[0035] To further clarify, the aforementioned fixed connection should be interpreted broadly unless otherwise explicitly specified and limited. For example, it may be welding, gluing, or integral molding, or other conventional methods well known to those skilled in the art.

[0036] The specific operation steps of this invention are as follows:

[0037] Equipment initialization and mold closing preparation: Start the main power supply of the device to preheat the hydraulic system, accumulator and temperature control system, and ensure that the hydraulic oil temperature is stable at 40-50℃ and the accumulator pressure reaches the preset initial value (usually 30-40MPa).

[0038] Check the lubrication status of each moving part to ensure that the surfaces of sliding parts such as piston 19, piston 21, and guide rod 25 are adequately lubricated and there is no risk of jamming; confirm that the external exhaust needle 14 and internal exhaust needle 17 are in their initial reset positions and that the exhaust passages are free of impurities.

[0039] The hydraulic drive system of the mold opening and closing mechanism 7 is activated, driving the moving mold 6 to slide smoothly towards the fixed mold 5 in the horizontal direction. During the mold closing process, the pressure sensor of the hydraulic system monitors the mold closing force in real time. When the end face of the moving mold 6 and the fixed mold 5 are completely in contact and the mold closing force reaches the preset value of 15-20MPa, the mold opening and closing mechanism 7 automatically locks. At this time, the cavity 26 of the fixed mold 5 and the moving mold 6 combine to form a sealed magnesium alloy frame forming cavity, ensuring that there is no metal leakage during the die casting process.

[0040] Metal liquid injection stage: Molten magnesium alloy liquid of a preset volume is injected into the injection chamber 2 through the pre-set grout on the external injection rod 3 located to the left of the inner piston 12. The temperature of the liquid metal must be strictly controlled at 650-700℃ to avoid severe oxidation due to excessive temperature or difficulty in filling due to excessive temperature.

[0041] After the injection is completed, the grouting tank automatically closes and seals. At this time, the accumulator begins to replenish energy, raising the accumulator pressure to the preset value (80-120MPa) required for injection, thus storing sufficient kinetic energy for subsequent high-pressure injection. Simultaneously, the gas discharge structure is in its initial working state: the external venting needle 14 penetrates deep into the cavity 26, including corners and other dead zones, and the eccentric fine hole of the internal venting needle 17 completely overlaps with the venting channel of the external venting needle 14, forming a venting passage with a maximum diameter of 2-3mm, preparing for rapid initial venting.

[0042] High-pressure injection and synchronous venting stage: When the injection control switch is activated, the accumulator instantly releases high-pressure oil, pushing the piston 9 in the injection chamber 2 to slide rapidly and seal towards the fixed mold 5. The piston 9 drives the piston 11 and the inner piston 12 to move synchronously at high speed through the connecting rod 10. The inner piston 12 slides and seals along the inner wall of the outer injection rod 3, injecting the molten magnesium alloy in the injection chamber 2 into the cavity 26 at a high speed of 1-5m / s and a high pressure of 80-120MPa, ensuring that the molten metal quickly fills the complex structure of the frame.

[0043] As the connecting rod 10 moves, it simultaneously drives the toothed rod 21 fixed on its side to move in a straight line. The gear 23 on the short shaft between the toothed rod 21 and the positioning plate 24 meshes and drives the gear 23 to rotate around the short shaft. At the same time, the gear 23 drives the meshing toothed rod 22 to move in the opposite direction in a straight line along the displacement groove of the injection chamber 2. The toothed rod 22 drives the guide tube 4 to move synchronously towards the fixed mold 5. The guide tube 4 pushes the external venting needle 14 to slide along the inner wall of the fixed mold 5, so that the external venting needle 14 gradually moves outward from the dead corner area of ​​the cavity 26, ensuring that the gas in the dead corner is continuously pushed to the venting channel.

[0044] At the same time, the connecting rod 10 drives the rotating rod 20 and the lower guide rod 25 to slide synchronously in a straight line along the guide tube 4 and the slide groove 19 in the injection chamber 2. The guide rod 25 is embedded in the spiral guide groove 18 at the end of the connecting shaft 13. As the guide rod 25 moves linearly, the spiral guide groove 18 converts the linear motion into the circumferential rotation of the connecting shaft 13. The connecting shaft 13 drives the inner exhaust needle 17 to rotate synchronously inside the outer exhaust needle 14. Because the fine holes of the internal venting needle 17 are eccentrically positioned, the overlapping area between the fine holes and the venting channel of the external venting needle 14 gradually decreases during rotation, achieving a dynamic gradual change in the venting diameter: In the early stage of die casting (20%-30% of the molten metal fills the cavity 26): the diameter is largest (2-3 mm), quickly expelling a large amount of air from the cavity 26 and preventing air stagnation and porosity; in the middle stage of die casting (30%-80% of the molten metal fills the cavity 26): the diameter gradually decreases (1-2 mm), balancing the discharge of residual gas with the stability of molten metal flow, preventing eddies caused by excessively large venting channels; in the later stage of die casting (80%-100% of the molten metal fills the cavity 26): the diameter is smallest (0.5-1 mm), effectively preventing molten metal backflow and oxide slag from entering the venting channel, avoiding venting blockage, and simultaneously expelling a small amount of residual gas. The discharged gas passes through the venting channels inside the external venting needle 14 and the guide tube 4, ultimately exiting the device, ensuring no gas residue remains in the cavity 26.

[0045] Pressure holding and solidification stage: After the molten metal completely fills the cavity 26, the injection system maintains constant pressure and enters the pressure holding stage, with the holding time set to 5-10 seconds. The core purpose of pressure holding is to prevent shrinkage cavities and porosity defects caused by volume shrinkage during the solidification process of the molten metal through continuous pressure.

[0046] During the pressure holding process, the accumulator monitors the injection system pressure in real time. If the pressure drops due to minor leaks in the pipeline or depressurization of the seals, the accumulator automatically releases a small amount of energy to replenish the pressure and maintain the pressure inside the cavity 26 within the preset range (80-100MPa). At this time, the internal venting needle 17 maintains its minimum orifice size, only venting a small amount of water vapor and oxidizing gas generated during the solidification of the molten metal, ensuring the internal structure of the casting is dense.

[0047] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A magnesium alloy frame die-casting molding apparatus comprising a base (1), characterized in that, The base (1) is fixedly provided with a base (8) and a fixed mold (5). The base (8) is fixedly provided with an injection chamber (2). The fixed mold (5) is provided with a cavity (26). A gas discharge structure is provided between the injection chamber (2) and the fixed mold (5). During die casting, the pressure and gas volume inside the cavity change dynamically with the filling process of the molten metal. The gas discharge structure is used to penetrate into the dead corner and discharge the residual gas. Under the coordinated action of movement and diameter change, it adapts to the exhaust requirements of different stages and is used to reduce the porosity, shrinkage and cold shut caused by gas accumulation in the casting. The injection chamber (2) is sealed and slidably equipped with piston one (9) and piston two (11), and a connecting rod (10) is fixedly installed between piston one (9) and piston two (11). The injection chamber (2) is sealed and slides with a conduit (4), and the fixed mold (5) is sealed and slides with an external exhaust needle (14). The gas discharge structure includes a gear rod (21) fixedly mounted on the connecting rod (10), two positioning plates (24) fixed inside the injection chamber (2), a short shaft fixedly mounted between the two positioning plates (24), a gear (23) rotatably mounted on the short shaft, a displacement groove opened on the injection chamber (2), a gear rod (22) fixedly mounted at one end of the guide tube (4), and the gear (23) meshes with both the gear rod (21) and the gear rod (22), and the gear rod (22) slides in the displacement groove; A rotating rod (20) is fixedly provided on one side of the connecting rod (10), and a guide rod (25) is fixedly provided at the lower end of the rotating rod (20). An internal exhaust needle (17) is rotatably arranged inside the external exhaust needle (14). One end of the internal exhaust needle (17) is provided with a fine hole, which is eccentrically arranged. Exhaust grooves (16) are provided in both the injection chamber (2) and the conduit (4). The exhaust grooves (16) provide ventilation space for the internal exhaust needle (17).

2. The magnesium alloy vehicle frame die-casting forming apparatus according to claim 1, characterized in that, The base (1) is provided with a mold opening and closing mechanism (7), and the mold opening and closing mechanism (7) is provided with a moving mold (6). The moving mold (6) is slidably disposed relative to the fixed mold (5), and the moving mold (6) is also provided with a cavity (26). The two cavities (26) cooperate with each other.

3. The magnesium alloy vehicle frame die-casting forming apparatus according to claim 2, characterized in that, An inner piston (12) is fixedly provided on one side of the piston 2 (11), and an outer injection rod (3) is fixedly connected between the fixed mold (5) and the injection chamber (2), and the inner piston (12) slides in the outer injection rod (3) in a sealed manner.

4. The magnesium alloy vehicle frame die-casting apparatus according to claim 1, characterized in that, Both the conduit (4) and the injection chamber (2) are provided with grooves (19), and the guide rod (25) slides in the grooves (19) for use.

5. The magnesium alloy vehicle frame die-casting apparatus according to claim 4, characterized in that, One end of the internal exhaust needle (17) is fixedly provided with a connecting shaft (13), and a rotating sleeve (15) is fixedly provided on the outside of the connecting shaft (13). The rotating sleeve (15) rotates in the guide tube (4) for use. One end of the connecting shaft (13) is provided with a guide groove (18), and the guide rod (25) slides in the guide groove (18) for use.

Images