Ejection pin of multilayer inverted structure at radar aperture

Abstract

The application relates to the technical field of die manufacturing, in particular to a demolding ejector rod of a multilayer reverse buckling structure at a radar hole, which comprises a fixing base, a forming insert and a core pulling block, the forming insert is fixedly connected to the fixing base and sleeved outside the core pulling block, and a mold cavity is formed between the forming insert and the core pulling block; the core pulling block comprises a first sliding part and a second sliding part, the first sliding part and the second sliding part are both slidingly connected to the fixing base, and the sliding direction of the first sliding part is perpendicular to the sliding direction of the second sliding part; a driver for driving the first sliding part to move is arranged in the fixing base, a linkage assembly is connected between the first sliding part and the second sliding part, and a reverse buckling forming block is fixedly connected to the side surface of the second sliding part away from the first sliding part. The application effectively solves the problems encountered in the demolding process of complex parts, and significantly improves the precision and production efficiency of die manufacturing.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of mold manufacturing, in particular to a demolding ejector rod of a multilayer undercut structure at a radar hole. BACKGROUND

[0002] In the field of mechanical manufacturing, especially in the molding process of plastic parts, the application of complex structure design is increasing, which promotes the improvement of product functionality and aesthetics. Especially in the automotive industry, the design of radar holes has become a key part of supporting advanced driver assistance systems. With the development of technology, the machining precision and production efficiency of parts are continuously improved, which drives the technological innovation of the entire manufacturing industry. However, such complex design also brings new challenges to mold manufacturing.

[0003] For the molding problem of radar holes in the front bumper of a car, two solutions are usually used in the industry: one is a separate insert design, which realizes molding and demolding during the opening and closing process by moving the insert fixed on the mold; the second is a combination of movable inserts and sliders, which uses a sliding mechanism to form more complex shape changes. These two methods have solved the problem of complex structure molding to some extent.

[0004] However, the existing separate insert and movable insert plus slider solutions still have great difficulties in the demolding process. Especially in the multilayer undercut structure, the demolding process is not only complex, but also prone to reduce the molding quality, which cannot guarantee the accurate molding and efficient demolding of the radar hole. This has become a technical problem that needs to be solved. SUMMARY

[0005] In order to effectively improve the demolding efficiency of the automobile shell, the demolding ejector rod of the multilayer undercut structure at the radar hole is improved.

[0006] The purpose of the application provides a demolding ejector rod of a multilayer undercut structure at a radar hole, which adopts the following technical scheme:

[0007] A demolding ejector rod of a multilayer undercut structure at a radar hole, comprising a fixed seat, a molding insert and a core pulling block, the molding insert is fixedly connected to the fixed seat, and the molding insert is sleeved outside the core pulling block, and a mold cavity is formed between the molding insert and the core pulling block; the core pulling block comprises a first sliding part and a second sliding part, the first sliding part and the second sliding part are both slidingly connected to the fixed seat, and the sliding direction of the first sliding part is perpendicular to the sliding direction of the second sliding part; a driver for driving the first sliding part to move is arranged in the fixed seat, a linkage assembly is connected between the first sliding part and the second sliding part, and a undercut molding block is fixedly connected to the side of the second sliding part away from the first sliding part.

[0008] By adopting the technical scheme, the demolding ejector rod of the multi-layer undercut structure at the radar hole is realized, which can effectively solve the problem of difficult demolding of complex-shaped parts in traditional molds. Specifically, the interaction between the forming insert and the core-pulling block on the fixed seat forms a stable mold cavity structure, which facilitates the manufacture of products with a multi-layer undercut structure. At the same time, the vertical sliding characteristics of the first sliding part and the second sliding part and the cooperative work of the driver and the linkage assembly enable the core-pulling block to accurately perform a complex motion trajectory, thereby realizing reliable demolding action of the undercut forming block. This design not only improves production efficiency, but also enhances the quality stability of the product.

[0009] Optionally, the linkage assembly includes a push-pull groove and a push-pull block, the push-pull groove is arranged on the side surface of the first sliding part and extends along the sliding direction of the first sliding part; the push-pull block is fixedly connected to the side surface of the second sliding part, and the push-pull block and the push-pull groove are in sliding cooperation; the push-pull groove is obliquely inwardly inclined along the direction of the undercut forming block towards the driver.

[0010] By adopting the technical scheme, the cooperation of the push-pull groove and the push-pull block enables the first sliding part and the second sliding part to stably link, and the obliquely inwardly inclined push-pull groove helps the second sliding part to form a stable demolding action with the undercut forming block when sliding in the vertical direction, thereby improving the reliability of the demolding process.

[0011] Optionally, the second sliding part includes a sliding block and an auxiliary strip, the sliding block is slidingly connected to one side of the fixed seat facing the forming insert; the auxiliary strip is fixedly connected to the sliding block, and the undercut forming block is fixedly connected to the side of the auxiliary strip away from the first sliding part.

[0012] By adopting the technical scheme, the second sliding part can stably slide on the fixed seat, and the undercut forming block is effectively connected to the sliding block through the auxiliary strip, thereby ensuring the stability and reliability of the undercut forming block during use. Specifically, the sliding block can smoothly slide on the fixed seat, and the design of the auxiliary strip enables the undercut forming block to be firmly installed thereon, thereby ensuring smooth operation of the entire structure in the working state.

[0013] Optionally, a rolling groove is arranged on the surface of the sliding block facing the fixed seat, and a rolling body is arranged in the rolling groove.

[0014] By adopting the technical scheme, a rolling groove is arranged on the surface of the sliding block facing the fixed seat, and a rolling body is arranged in the rolling groove, which can effectively reduce the friction between the sliding block and the fixed seat, improve the smoothness and stability of the sliding block, and prolong the service life of the device.

[0015] Optionally, the fixing base is provided with a connecting rod, the forming insert is provided with a connecting groove matched with the connecting rod, and the forming insert is provided with a fixing mechanism for fixing the connecting rod in the connecting groove.

[0016] By adopting the above technical scheme, the connection between the fixing base and the forming insert is more stable, facilitating assembly and disassembly, and improving production efficiency.

[0017] Optionally, the fixing mechanism comprises a locking block and a locking groove, an inner wall of the connecting groove is provided with a sliding groove, the locking block slides in the sliding groove, the locking groove is formed on the outer side surface of the connecting rod and is inserted with the locking block, the forming insert is provided with a guide hole communicated with the sliding groove, and the guide hole is provided with a guide rod connected with the locking block.

[0018] By adopting the above technical scheme, the locking block in the fixing mechanism can slide in the sliding groove and be inserted with the locking groove on the connecting rod, so that the connecting rod is quickly fixed and disassembled in the forming insert, improving assembly efficiency.

[0019] Optionally, the sliding groove is provided with a locking spring, one end of the locking spring is fixedly connected to the wall of the sliding groove, the other end of the locking spring is fixedly connected to the locking block, and the end surface of the locking block facing the fixing base is inclined.

[0020] By adopting the above technical scheme, the locking spring can make the locking block automatically inserted into the locking groove when not subjected to external force, realizing quick locking between the connecting rod and the connecting groove, so as to ensure the stable connection between the forming insert and the fixing base. The end surface of the locking block facing the fixing base is inclined, which is convenient to shrink into the sliding groove under external force, simplifying the assembly process and improving the assembly efficiency.

[0021] Optionally, the end of the guide rod away from the locking block is provided with a handle, and the side surface of the forming insert is provided with a groove for storing the handle.

[0022] By adopting the above technical scheme, the end of the guide rod away from the locking block is provided with a handle, and the side surface of the forming insert is provided with a groove for storing the handle, so that the operator can pull the locking block through the handle, thereby conveniently and quickly realizing the separation of the locking block and the locking groove, improving the operation convenience of the fixing mechanism and the assembly efficiency of the demolding ejector rod.

[0023] Optionally, the end of the core pulling block away from the fixing base is conical, and the diameter of the end of the core pulling block away from the fixing base is smaller than the diameter of the end of the core pulling block close to the fixing base.

[0024] By adopting the technical scheme, the end of the core-pulling block away from the fixed seat is designed in a conical shape, and the diameter of the end is smaller than that of the end close to the fixed seat, so that efficient demolding of the core-pulling block in the demolding process is realized, the jamming phenomenon is reduced, and the demolding success rate is improved.

[0025] In summary, the present application has at least the following beneficial technical effects:

[0026] 1. By setting the mold cavity structure among the fixed seat, the forming insert block and the core-pulling block, and combining the linkage assembly of the first sliding part and the second sliding part, the accurate forming and smooth demolding of the multi-layer reverse buckling structure can be realized, and the problem of complex demolding process and easy to cause the forming quality to decrease in the prior art is solved;

[0027] 2. By setting the push-pull groove and the push-pull block structure between the first sliding part and the second sliding part, and the inwardly inclined setting of the push-pull groove, the sliding action can be smoothly completed under the driving of the driver, and the stability and reliability during demolding are improved;

[0028] 3. By setting the rolling groove and the built-in rolling body on the sliding block, the friction between the sliding block and the fixed seat during sliding can be reduced, the smoothness of the demolding operation is further ensured, and the demolding efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a partial structure schematic view of a demolding ejector rod of a multi-layer reverse buckling structure at a radar hole in an embodiment of the present application;

[0030] Figure 2 is a structure sectional view of the first embodiment of the present application, mainly used for showing the connection schematic view of the fixed seat, the forming insert block, the core-pulling block and the driver;

[0031] Figure 3 is a partial structure sectional view of the second embodiment of the present application, mainly used for showing the connection schematic view of the fixed seat and the forming insert block;

[0032] Figure 4 is Figure 3 an enlarged view of part A in

[0033] MARKED FOR EXPLANATION: 1, fixed seat; 2, forming insert block; 3, core-pulling block; 31, first sliding part; 32, second sliding part; 4, driver; 5, linkage assembly; 51, push-pull groove; 52, push-pull block; 6, reverse buckling forming block; 7, sliding block; 8, auxiliary strip; 9, rolling groove; 10, rolling body; 11, connecting rod; 12, connecting groove; 13, fixing mechanism; 131, locking block; 132, locking groove; 133, sliding groove; 14, guide hole; 15, guide rod; 16, locking spring; 17, handle; 18, groove. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings Figures 1-4 The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings

[0035] The present application provides a demolding ejector rod for a multilayer reverse-drawing structure at a radar hole. Figure 1 The demolding ejector rod for a multilayer reverse-drawing structure at a radar hole comprises a fixed seat 1, a shaped insert 2, and a core-pulling block 3. Figure 2 The core-pulling block 3 comprises a first sliding part 31 and a second sliding part 32. The first sliding part 31 and the second sliding part 32 are both slidingly connected to the fixed seat 1, and the sliding direction of the first sliding part 31 is perpendicular to the sliding direction of the second sliding part 32. A driver 4 is arranged in the fixed seat 1 to drive the first sliding part 31 to move. A linkage assembly 5 is connected between the first sliding part 31 and the second sliding part 32. A reverse-drawing shaped block 6 is fixedly connected to the side of the second sliding part 32 away from the first sliding part 31.

[0036] Embodiment 1

[0037] The present application provides a demolding ejector rod for a multilayer reverse-drawing structure at a radar hole. Figure 1 The demolding ejector rod for a multilayer reverse-drawing structure at a radar hole comprises a fixed seat 1, a shaped insert 2, and a core-pulling block 3. Figure 2 The core-pulling block 3 comprises a first sliding part 31 and a second sliding part 32. The first sliding part 31 and the second sliding part 32 are both slidingly connected to the fixed seat 1, and the sliding direction of the first sliding part 31 is perpendicular to the sliding direction of the second sliding part 32. A driver 4 is arranged in the fixed seat 1 to drive the first sliding part 31 to move. A linkage assembly 5 is connected between the first sliding part 31 and the second sliding part 32. A reverse-drawing shaped block 6 is fixedly connected to the side of the second sliding part 32 away from the first sliding part 31.

[0038] Specifically, the fixed seat 1 can be made of high-strength steel or alloy materials to ensure sufficient rigidity and strength. For example, the fixed seat 1 can be made of cast iron material, or can be made of aluminum alloy or other alloy materials, such as special stainless steel. The specific structure of the fixed seat 1 is designed according to the actual demand, which can adopt different fixing methods such as bolts, welding or other mechanical fixing methods. The size and shape of the fixed seat 1 can be adjusted according to the specific application scene to ensure stable installation. For example, the fixed seat 1 can be designed as a flat plate or a U-shaped structure.

[0039] The shaped insert 2 can also be made of high-strength materials, such as stainless steel or hard alloy. The specific shape of the shaped insert 2 can be customized according to the required shaped product. For example, the shaped insert 2 can be cylindrical, rectangular or other special shapes. The shaped insert 2 is fixed on the fixed seat 1 by screws, keyways and other methods. In addition, in order to improve the wear resistance and corrosion resistance, the surface of the shaped insert 2 can be chrome plated or sprayed with wear-resistant coating.

[0040] The core pulling block 3 is usually made of high-hardness alloy material to facilitate the demolding operation after shaping. The outer diameter of the core pulling block 3 gradually tapers to form a conical structure, which facilitates smooth exit during demolding. The core pulling block 3 can be provided with reinforcing ribs inside to increase its stability. For example, the reinforcing ribs can be arranged in a cross or spiral manner. The core pulling block 3 can also be provided with a lubricating coating on the outside to reduce friction and increase service life. The outer surface of the core pulling block 3 can be further polished to reduce surface roughness and improve demolding performance.

[0041] The first sliding part 31 mainly includes a sliding rail and a sliding block. The sliding rail can be a linear guide rail or a ball screw. The sliding rail material can be selected from copper alloy or steel, which has good wear resistance. The sliding block can be made of bearing steel or ceramic material to ensure low friction resistance and smooth operation. The sliding rail and the sliding block are precisely fitted, for example, the sliding rail can be a U-shaped rail, and the sliding block is embedded in the rail and tightly fitted with it to ensure that there is no looseness during sliding.

[0042] The second sliding part 32 includes a sliding block 7 and an auxiliary strip 8. The sliding block 7 is usually a flat plate structure and can slide freely on the fixed seat 1. The contact area between the sliding block 7 and the fixed seat 1 is large, which can reduce the unit pressure and prevent wear. The material of the sliding block 7 can be selected from high-strength steel or copper alloy. The auxiliary strip 8 can be a flat and long strip structure, which is fixed on one side of the sliding block 7 and plays a stabilizing role. The material of the auxiliary strip 8 is usually selected from carbon fiber composite material or high-strength aluminum alloy.

[0043] The linkage assembly 5 mainly consists of a push-pull groove 51 and a push-pull block 52. The push-pull groove 51 is arranged on the side of the first sliding part 31 and extends along the sliding direction of the first sliding part 31. The cross-sectional shape of the push-pull groove 51 can be rectangular or V-shaped. The push-pull block 52 is fixedly connected to the side of the second sliding part 32, and the push-pull block 52 is in sliding cooperation with the push-pull groove 51. The size of the push-pull block 52 should be appropriately larger than the width of the push-pull groove 51 to ensure that it does not come off during sliding. The push-pull block 52 can be made of hard alloy, which has good wear resistance. The push-pull groove 51 is arranged obliquely inward along the direction of the undercut forming block 6 towards the driver 4. This design forms a stable linkage relationship between the first sliding part 31 and the second sliding part 32, effectively transmits power, and realizes precise control.

[0044] The undercut forming block 6 is fixedly connected to the side of the second sliding part 32 away from the first sliding part 31. The specific shape of the undercut forming block 6 can be adjusted according to the structure of the actual forming part. For example, the undercut forming block 6 can be cylindrical or rectangular to adapt to different shapes of forming parts. The material of the undercut forming block 6 can also be selected as high-hardness alloy material to improve wear resistance. The surface of the undercut forming block 6 is polished to reduce surface roughness and improve demolding effect.

[0045] The implementation principle of the embodiment is:

[0046] Through the cooperation of the fixed seat 1, the forming insert 2, and the core-pulling block 3, a demolding ejector rod with a multi-layer undercut structure is formed. The vertical sliding structure of the first sliding part 31 and the second sliding part 32 effectively realizes the complex demolding process. The driver 4 in the fixed seat 1 is responsible for pushing the first sliding part 31 to move, and the linkage assembly 5 ensures the synchronous movement between the first sliding part 31 and the second sliding part 32. Such design not only simplifies the demolding process, improves work efficiency, but also guarantees the quality of the forming part. Through reasonable material selection and structural optimization, the reliability and durability of the whole machine are further improved.

[0047] Embodiment 2

[0048] The difference between this embodiment and the above-mentioned embodiments is that: Figure 3 and Figure 4 The structure design of the fixed seat 1 is further optimized, and the connecting rod 11 is added, so that the connection between the fixed seat 1 and the forming insert 2 is more firm and reliable.

[0049] Specifically, in addition to the basic structure mentioned above, the fixing base 1 is particularly provided with connecting rods 11 for enhancing the connecting strength between the fixing base 1 and the shaped insert 2. The connecting rods 11 can be one or more, the number being determined according to the actual needs. For example, the connecting rods 11 can be cylindrical or prismatic. The connecting rods 11 can be made of high-strength steel or alloy materials, such as special steel or aluminum alloy. The length of the connecting rods 11 can be set according to the actual needs, and in general cases, the length of the connecting rods 11 should be slightly shorter than the thickness of the fixing base 1, so as to avoid interfering with the movement of other components. The diameter of the connecting rods 11 is usually between 5 mm and 10 mm, so as to ensure sufficient strength and stability.

[0050] The shaped insert 2 is provided with connecting grooves 12 matched with the connecting rods 11. The connecting grooves 12 can be one or more, the number being determined according to the actual needs. The specific shape of the connecting grooves 12 can be determined according to the cross-sectional shape of the connecting rods 11. For example, if the connecting rods 11 are circular, the connecting grooves 12 are also circular; if the connecting rods 11 are square, the connecting grooves 12 are also square. The depth of the connecting grooves 12 should be sufficient to accommodate the full length of the connecting rods 11, so as to ensure the close combination of the two. The depth of the connecting grooves 12 is usually between 10 mm and 20 mm, so as to ensure the connecting strength.

[0051] In addition, the shaped insert 2 is provided with a fixing mechanism 13 for fixing the connecting rods 11 in the connecting grooves 12. The fixing mechanism 13 includes a locking block 131 and a locking groove 132. The locking groove 132 is formed on the outer side of the connecting rod 11 and is inserted with the locking block 131. The locking block 131 can slide in the sliding groove 133 and is kept in the locked state by the locking spring 16. The size of the locking block 131 should be slightly larger than that of the locking groove 132, so as to ensure that it can be tightly inserted. The locking block 131 can be made of high-strength alloy steel, so as to ensure sufficient hardness and toughness. The length of the locking groove 132 is usually between 20 mm and 30 mm, so as to ensure the locking effect. The selection of the locking spring 16 is also very important, which should have sufficient elasticity and recovery ability. One end of the locking spring 16 is fixedly connected to the wall of the sliding groove 133, and the other end is fixedly connected to the locking block 131. The end face of the locking block 131 towards the fixing base 1 is inclined, so that it is easier to be inserted into the locking groove 132. The locking spring 16 is usually made of spring steel wire with a diameter of 2 mm to 3 mm. In addition, in order to facilitate the operation of the locking block 131, a handle 17 can be provided on the side of the shaped insert 2. The shape and size of the handle 17 can be designed according to the actual situation. For example, the handle 17 can be ring-shaped, T-shaped or other shapes that are convenient to grip. The handle 17 is usually made of metal materials, such as aluminum alloy or stainless steel. The side of the shaped insert 2 is also provided with a groove 18 for storing the handle 17, so as to hide it when it is not needed, without affecting the appearance.

[0052] The guide rod 15 is connected to the locking block 131 through the guide hole 14, achieving smooth sliding of the locking block 131. The guide rod 15 is made of high-strength steel or hard alloy, and its diameter is usually between 3mm and 5mm to ensure sufficient strength and precision. The guide hole 14 is in communication with the sliding groove 133, and the diameter of the guide hole 14 is usually slightly larger than that of the guide rod 15 to ensure the guiding effect. The guide hole 14 is provided with the guide rod 15 connected to the locking block 131.

[0053] The implementation principle of the embodiment is:

[0054] By increasing the connecting rod 11 and the corresponding fixing mechanism 13, the connection reliability between the fixing seat 1 and the shaped insert 2 is further strengthened. The cooperation of the locking block 131 and the locking groove 132, as well as the action of the locking spring 16, make the assembly of the whole system more stable. In addition, by setting the handle 17 and the groove 18, it is convenient for operation and maintains the overall neatness and beauty. Such optimization design not only improves the service life of the equipment, but also provides convenience for subsequent maintenance and maintenance work.

[0055] In summary, the embodiment optimizes the connection structure of the fixing seat 1 and the shaped insert 2, significantly improves the overall stability and reliability of the demolding ejector rod, and better meets the actual production and application requirements.

[0056] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, therefore: any equivalent changes made according to the structure, shape, principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A demolding ejector pin of a multilayer inverted structure at a radar aperture, characterized in that, The utility model relates to a core-pulling mould, including fixed seat (1), shaped insert (2) and core-pulling block (3), shaped insert (2) is fixedly connected on fixed seat (1), and shaped insert (2) is sleeved in the outside of core-pulling block (3), and the cavity is formed between shaped insert (2) and core-pulling block (3);The core-pulling block (3) includes first sliding part (31) and second sliding part (32), both first sliding part (31) and second sliding part (32) are slidably connected on fixed seat (1), and the sliding direction of first sliding part (31) is perpendicular with the sliding direction of second sliding part (32);The driver (4) for driving first sliding part (31) moves is provided in fixed seat (1), and the linkage assembly (5) is connected between first sliding part (31) and second sliding part (32), and the side away from first sliding part (31) of second sliding part (32) is fixedly connected with inverted buckle shaped block (6); The linkage assembly (5) includes push-pull groove (51) and push-pull block (52), the push-pull groove (51) is provided on the side of first sliding part (31) and extends along the sliding direction of first sliding part (31);The push-pull block (52) is fixedly connected on the side of second sliding part (32), and the push-pull block (52) is slidably matched with push-pull groove (51);The push-pull groove (51) is obliquely arranged towards the direction of inverted buckle shaped block (6) towards driver (4);The second sliding part (32) includes sliding block (7) and auxiliary strip (8), and sliding block (7) is flat plate structure, and auxiliary strip (8) is flat strip structure;The side of sliding block (7) towards shaped insert (2) is slidably connected on fixed seat (1);The auxiliary strip (8) is fixedly connected on sliding block (7), and the side away from first sliding part (31) of auxiliary strip (8) is fixedly connected with multiple groups of inverted buckle shaped block (6) distributed upwards and downwards;The fixed seat (1) is provided with connecting rod (11), the shaped insert (2) is provided with connecting groove (12) matched with connecting rod (11), and the shaped insert (2) is provided with fixing mechanism (13) for fixing connecting rod (11) in connecting groove (12);The fixing mechanism (13) includes locking block (131) and locking groove (132), the inner wall of connecting groove (12) is provided with sliding groove (133), and the locking block (131) slides in sliding groove (133);The locking groove (132) is formed on the outer side of connecting rod (11) and is inserted with locking block (131);The shaped insert (2) is provided with guide hole (14) communicated with sliding groove (133), and the guide hole (14) is provided with guide rod (15) connected with locking block (131).

2. The demolding ejector rod of a multilayer inverted cup structure at a radar aperture of claim 1, wherein, The surface of sliding block (7) towards fixed seat (1) is provided with rolling groove (9), and rolling body (10) is built-in rolling groove (9).

3. The demolding ejector pin with a multi-layered undercut structure at the radar hole according to claim 1, characterized in that, Locking spring (16) is arranged in the sliding groove (133), one end of the locking spring (16) is fixedly connected to the wall of the sliding groove (133), the other end is fixedly connected to the locking block (131), and the end face of the locking block (131) towards the fixed base (1) is inclined.

4. The demolding ejector rod of a multilayer inverted cup structure at a radar aperture of claim 3, wherein, The end of the guide rod (15) away from the locking block (131) is provided with a handle (17), and the side of the shaped insert block (2) is provided with a groove (18) for storing the handle (17).

5. The demolding ejector rod of a multilayer inverted cup structure at a radar aperture of claim 1, wherein, The end of the core pulling block (3) away from the fixed base (1) is conical, and the diameter of the end of the core pulling block (3) away from the fixed base (1) is smaller than the diameter of the end of the core pulling block (3) close to the fixed base (1).

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