A necking tool for the rubber main spring of a hydraulic bushing and its necking method

Abstract

The present invention discloses a necking tooling for the rubber main spring of a hydraulic bushing, which includes a base, a positioning pin, a lower pressing block, a twelve-petal die, a pressing plate, a tapered cover, an upper pressing block and an upper cover plate. The twelve-petal die is arranged at the top end of the base. The tapered cover is in a conical shape with a smaller upper part and a larger lower part. The lower opening of the tapered cover is sleeved on the twelve-petal die, and an adjusting plate is arranged between the lower end of the tapered cover and the upper end of the positioning edge of the twelve-petal die. The upper pressing block is arranged in the upper opening of the tapered cover. The upper cover plate is connected to the top end of the tapered cover by bolts. An adjusting piece is arranged between the bottom end of the upper cover plate and the top end of the upper pressing block. This necking tooling has a limiting mechanism at both ends and the middle of the rubber main spring, can realize the necking process of the rubber main spring with an inner cage having a window, and after necking, the window end face and the middle part have no deformation, the necking amount and the preloading amount can be adjusted, and the operation is convenient. The present invention also discloses a necking method for the necking tooling of the rubber main spring of a hydraulic bushing.

Description

Technical Field

[0001] The present invention relates to a necking tool for a rubber main spring of a hydraulic bushing and a necking method thereof. Background Art

[0002] Please refer to Figure 1 , an automotive hydraulic bushing assembly generally consists of a rubber main spring 1', a rubber stopper 2', a plastic runner 3' and a metal outer sleeve 4', etc. Among them, the rubber main spring 1' is composed of an inner cage 11', a mandrel 12' and rubber 13'. In order to eliminate the residual stress during the rubber vulcanization process, after the vulcanization process is completed, the rubber main spring 1' will be subjected to a necking process.

[0003] Please refer to Figure 2 , Figure 3 and Figure 4 , in the rubber main spring 1', the inner cage 11' has a structure of two windows 111', and the circumferential direction is an asymmetric structure. Due to the non-absolute uniformity of each component of the rubber main spring, the pulling effect of the vertical ribs on the side wall of the window structure, and the processing error of the necking tool, etc., when using the traditional necking tool 100' for the rubber main spring of the hydraulic bushing to perform necking, the rubber main spring 1' is directly placed in the necking tool 100'. There is no corresponding limiting mechanism at both ends and the middle of the rubber main spring. During the necking process, the upper end face B, the lower end face C of the inner cage window, and the corresponding upper end face A and lower end face D of the inner cage will undergo "twisting" deformation, which will cause problems such as poor flatness of the upper end face E and lower end face F at the window position of the rubber main spring 1', difficult assembly of the plastic runner, and liquid leakage of the hydraulic bushing. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a necking tool for a rubber main spring of a hydraulic bushing, which has limiting mechanisms at both ends and the middle of the rubber main spring, can realize the necking process of the rubber main spring composed of an inner cage with windows, and after necking, there is no deformation at the window end face and the middle, the necking amount and the preloading amount can be adjusted, and the operation is convenient.

[0005] Another purpose of the present invention is to provide a necking method for a necking tool of a rubber main spring of a hydraulic bushing.

[0006] A technical solution to achieve the above purpose is: a necking tool for a rubber main spring of a hydraulic bushing, including a base, a positioning pin, a lower pressing block, a twelve-petal die, a pressing plate, a cone cover, an upper pressing block and an upper cover plate, wherein:

[0007] A positioning pin mounting hole and a lower pressing block mounting hole are opened at the top of the base. The positioning pin mounting hole and the lower pressing block mounting hole are coaxially arranged inside and outside, and the positioning pin mounting hole is located at the center of the base;

[0008] The head of the positioning pin is arranged in the positioning pin mounting hole in an interference fit manner;

[0009] The bottom end of the lower pressing block is press-fitted in the lower pressing block mounting hole;

[0010] The twelve-petal die is composed of twelve die petals evenly distributed in the circumferential direction. Each die petal is formed by connecting a vertical part and a horizontal part in an L shape. An upward convex end face and a downward convex end face protruding inward are provided on the inner wall surface of the vertical part of the die petal; A circumferential pre-compression spring is arranged between every two adjacent die petals; The horizontal parts of the twelve die petals form the positioning edge of the twelve-petal die;

[0011] The twelve-petal die is arranged at the top end of the base, and the twelve die petals are all located outside the lower pressing block;

[0012] The pressing plate is in a ring structure. The pressing plate is connected to the top end of the base by bolts, and the pressing plate presses on the positioning edge of the twelve-petal die;

[0013] The conical cover is in a conical shape with a smaller top and a larger bottom. The lower end opening of the conical cover is sleeved on the twelve-petal die, and an adjusting plate is arranged between the lower end of the conical cover and the upper end of the positioning edge of the twelve-petal die;

[0014] An annular inner convex platform protruding inward is provided on the inner wall of the upper end opening of the conical cover;

[0015] The top end of the upper pressing block has an annular outer convex platform protruding outward. The upper pressing block is arranged in the upper end opening of the conical cover, and the annular outer convex platform is located above the annular inner convex platform;

[0016] An axial blind hole and two magnet mounting holes are provided at the top end of the upper pressing block. The axial blind hole is located at the center of the upper pressing block; An axial pre-compression spring is arranged in the axial blind hole; A high-temperature magnet is arranged in each magnet mounting hole;

[0017] The upper cover plate is connected to the top end of the conical cover by bolts;

[0018] An adjusting piece is arranged between the bottom end of the upper cover plate and the top end of the upper pressing block, and the adjusting piece is adsorbed on the high-temperature magnet.

[0019] For the above-mentioned necking tooling of the rubber main spring of the hydraulic bushing, wherein, a spring mounting hole is provided on the vertical part of each die petal, and the spring mounting holes of the twelve die petals are distributed along the same circumference; The two ends of the circumferential pre-compression spring between every two adjacent die petals are respectively located in the corresponding spring mounting holes.

[0020] The above-mentioned necking tooling for the rubber main spring of a hydraulic bushing, wherein the rubber main spring is arranged inside the twelve-piece die. The top end of the rubber main spring contacts the bottom end of the upper pressing block, and the bottom end of the rubber main spring contacts the top end of the lower pressing block. The tail end of the positioning pin is inserted into the mandrel of the rubber main spring. The upper end surface at the window position of the rubber main spring is located above the upper convex end surface of the die segment, and there is a gap of 0.2 - 0.5 mm between them. The lower end surface at the window position of the rubber main spring is located below the lower convex end surface of the die segment, and there is a gap of 0.2 - 0.5 mm between them.

[0021] The present invention also provides a necking method for the rubber main spring of a hydraulic bushing. Necking is performed using the above-mentioned necking tooling for the rubber main spring of a hydraulic bushing, and it includes the following steps:

[0022] S1, Necking tooling assembly step, which specifically includes the following processes:

[0023] S11, Lower component assembly process: The head of the positioning pin is press-fitted into the positioning pin mounting hole of the base, and the bottom end of the lower pressing block is press-fitted into the lower pressing block mounting hole of the base. Then, the twelve-piece die is arranged on the top end of the base, and a circumferential pre-compression spring is arranged between every two adjacent die segments. Next, the pressing plate is connected to the base by bolts, and the pressing plate presses on the positioning edge of the twelve-piece die to complete the assembly of the lower components.

[0024] S12, Upper component assembly process: An axial pre-compression spring is placed in the axial blind hole at the center of the upper pressing block, and a high-temperature magnet is arranged in each of the two magnet mounting holes of the upper pressing block. Then, the upper pressing block is placed inside the upper opening of the conical cover, an adjusting piece is placed on the top end of the upper pressing block, and then the upper cover plate is connected to the top end of the conical cover by bolts to complete the assembly of the upper components. Under the action of gravity, the annular outer convex platform of the upper pressing block overlaps on the annular inner convex platform of the conical cover.

[0025] S13, The lower opening of the conical cover of the upper component is sleeved on the twelve-piece die of the lower component, and an adjusting plate is arranged between the lower end of the conical cover and the upper end of the positioning edge of the twelve-piece die to complete the assembly of the entire necking tooling.

[0026] S2, Remove the upper component. The conical cover is removed from the twelve-piece die, and the twelve die segments of the twelve-piece die radially expand outward under the action of the circumferential pre-compression spring. Then, the rubber main spring is placed inside the twelve-piece die, and the mandrel of the rubber main spring is sleeved on the positioning pin. The bottom end of the rubber main spring contacts the top end of the lower pressing block.

[0027] S3, The lower opening of the conical cover of the upper component is sleeved on the twelve-piece die, the bottom end of the upper pressing block contacts the top end of the rubber main spring, and under the action of the axial pre-compression spring, the upper pressing block presses on the top end of the rubber main spring.

[0028] In S4, the conical cover is pressed down, and the twelve die segments of the twelve-segment die radially converge inward to perform necking on the rubber main spring.

[0029] In S5, after the necking is in place, the upper assembly is removed, the conical cover is taken off the twelve-segment die, and the twelve die segments of the twelve-segment die radially expand under the action of the circumferential pre-compression spring, and then the rubber main spring is taken out to complete the entire necking process of the rubber main spring.

[0030] Adopting the technical solution of the necking tooling for the rubber main spring of the hydraulic bushing of the present invention and its necking method, there are limiting mechanisms at both ends and the middle of the rubber main spring, which can realize the necking process of the rubber main spring composed of an inner cage with windows. After necking, the window end face and the middle part have no deformation, the necking amount and the pre-compression amount can be adjusted, and the operation is convenient. Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of an automotive hydraulic bushing assembly;

[0032] Figure 2 It is a schematic structural diagram of the rubber main spring;

[0033] Figure 3 It is a schematic structural diagram of the inner cage in the rubber main spring;

[0034] Figure 4 It is a schematic structural diagram of a conventional necking tooling for the rubber main spring of a hydraulic bushing;

[0035] Figure 5 It is a structural diagram of a necking tooling for the rubber main spring of a hydraulic bushing according to the present invention;

[0036] Figure 6 It is a structural diagram of a single die segment of the twelve-segment die. Detailed Embodiments

[0037] In order to enable those skilled in the art of the present technology to better understand the technical solution of the present invention, the following will describe its detailed embodiments in detail with reference to the accompanying drawings:

[0038] Please refer to Figure 1 、 Figure 2 and Figure 3 , the rubber main spring 1' is composed of an inner cage 11', a mandrel 12' and rubber 13'. The inner cage 11' has two windows 111'. The window position of the rubber main spring 1' has an upper end face E and a lower end face F.

[0039] Please refer to Figure 5 and Figure 6 , an embodiment of the present invention, a necking tooling for the rubber main spring of a hydraulic bushing, includes a base 4, a positioning pin 6, a pressing block 7, a twelve-segment die 2, a pressing plate 3, a conical cover 1, an upper pressing block 10 and an upper cover plate 14.

[0040] The top end of the base 4 is provided with a dowel pin mounting hole and a pressing block mounting hole. The dowel pin mounting hole and the pressing block mounting hole are coaxially arranged, one inside the other, and the dowel pin mounting hole is located at the center of the base 4; the head of the dowel pin 6 is press-fitted into the dowel pin mounting hole; the bottom end of the pressing block 7 is press-fitted into the pressing block mounting hole; the twelve-piece die 2 is composed of twelve die segments 21 evenly distributed in the circumferential direction. Each die segment 21 is formed by connecting a vertical portion 211 and a horizontal portion 212 in an L-shape. The inner wall surface of the vertical portion of the die segment 211 is provided with an inwardly protruding upper convex end face 213 and a lower convex end face 214; a circumferential pre-compression spring 9 is arranged between every two adjacent die segments 21. A spring mounting hole 215 is provided on the vertical portion 211 of each die segment 21. The spring mounting holes 215 of the twelve die segments 21 are distributed along the same circumference; the two ends of the circumferential pre-compression spring 9 between every two adjacent die segments 21 are respectively located in the corresponding spring mounting holes 215; the horizontal portions of the twelve die segments 21 form the positioning edge 22 of the twelve-piece die.

[0041] The twelve-piece die 2 is arranged at the top end of the base 4, and all twelve die segments 21 are located outside the pressing block 7; the pressing plate 3 is of an annular structure. The pressing plate 3 is connected to the top end of the base 4 by bolts 8, and the pressing plate 3 presses on the positioning edge 21 of the twelve-piece die 2. In this way, the pressing plate 3 restricts the vertical displacement of the twelve-piece die 2.

[0042] The cone cover 1 is in a conical shape with a smaller top and a larger bottom. The lower end opening of the cone cover 1 is sleeved on the twelve-piece die 2. An adjusting plate 5 is arranged between the lower end of the cone cover 1 and the upper end of the positioning edge 22 of the twelve-piece die 2. The change of the necking amount can be realized by designing different thicknesses of the adjusting plate 5; an inwardly protruding annular inner convex platform 16 is arranged on the inner wall of the upper end opening of the cone cover 1; the top end of the upper pressing block 10 has an outwardly protruding annular outer convex platform 101. The upper pressing block 10 is arranged in the upper end opening of the cone cover 1, and the annular outer convex platform 101 is located above the annular inner convex platform 16. The annular outer convex platform 101 and the annular inner convex platform 16 form a snap limit structure, which can restrict the downward displacement of the upper pressing block 10; the upper cover plate 14 is connected to the top end of the cone cover 1 by bolts 13; the upward movement displacement of the upper pressing block 10 can be restricted through the upper cover plate 14. In this way, a certain vertical displacement of the upper pressing block 10 can be restricted by the upper cover plate 14 and the annular inner convex platform 16 in the cone cover 1.

[0043] The top end of the upper pressing block 10 is provided with an axial blind hole and two magnet mounting holes. The axial blind hole is located at the center of the upper pressing block 10; an axial pre-compression spring 11 is arranged in the axial blind hole; a high-temperature magnet 15 is arranged in each magnet mounting hole.

[0044] An adjusting piece 12 is arranged between the bottom end of the upper cover plate 14 and the top end of the upper pressing block 10, and the adjusting piece 12 is adsorbed on the high-temperature magnet 15. The compression amounts of the upper and lower end faces of the rubber main spring can be realized by designing different thicknesses of the adjusting piece 12.

[0045] When the necking tooling for the rubber main spring of the hydraulic bushing of the present invention is in use, the rubber main spring 1' is arranged in the twelve-petal die 2. The top end of the rubber main spring 1' contacts the bottom end of the upper pressing block 10, and the bottom end of the rubber main spring 1' contacts the top end of the lower pressing block 7. The tail end of the positioning pin 6 is inserted into the mandrel 12' of the rubber main spring 1'. The positioning pin 6 is used to limit the rotation of the rubber main spring 1' and at the same time center the rubber main spring 1'. The upper end face E at the window position of the rubber main spring 1' is located above the upper convex end face 213 of the die petal 21, and there is a gap of 0.2 - 0.5 mm between them. The lower end face F at the window position of the rubber main spring 1' is located below the lower convex end face 214 of the die petal 21, and there is a gap of 0.2 - 0.5 mm between them. These gaps of 0.2 - 0.5 mm can ensure the normal progress of the initial necking. During the necking process, the upper convex end face 213 and the lower convex end face 214 limit the window position of the rubber main spring 1'. Twelve pre-compression springs 9 are placed between the twelve-petal dies 2 to ensure that after the cone cover 1 moves upward, the twelve-petal die 2 can expand radially outward under the action of the circumferential pre-compression springs 9 and separate smoothly. The change of the necking amount can be realized by designing different thicknesses of the adjusting plate 5, and the compression amounts of the upper and lower end faces of the rubber main spring can be realized by designing different thicknesses of the adjusting piece 12, finally achieving the purpose of no deformation of the cage and rubber in the window area of the rubber main spring.

[0046] A necking method for the rubber main spring of a hydraulic bushing, which uses the necking tooling for the rubber main spring of the present invention for necking, includes the following steps:

[0047] S1, the necking tooling assembly step, specifically including the following processes:

[0048] S11, the lower component assembly process: The head of the positioning pin 6 is arranged in the positioning pin mounting hole of the base 4 with an interference fit, and the bottom end of the lower pressing block 7 is arranged in the lower pressing block mounting hole of the base 6 with an interference fit. Then the twelve-petal die 2 is arranged on the top end of the base 1, and a circumferential pre-compression spring 9 is arranged between every two adjacent die petals 21. Then the pressing plate 3 is connected to the base 4 by bolts 8, and the pressing plate 3 presses on the positioning edge 22 of the twelve-petal die 2 to complete the assembly of the lower component.

[0049] S12, upper component assembly process: placing an axial pre-compression spring 11 in the axial blind hole at the center of the upper pressing block 10, and respectively setting a high-temperature magnet 15 in the two magnet mounting holes of the upper pressing block 10; then placing the upper pressing block 10 in the upper end opening of the cone cover 1, placing an adjustment sheet 12 on the top of the upper pressing block 10, and then connecting the upper cover plate 14 to the top of the cone cover 1 by bolts 13 to complete the assembly of the upper component; under the action of gravity, the annular outer boss 101 of the upper pressing block 10 overlaps the annular inner boss 16 of the cone cover 1;

[0050] S13, the lower end opening of the cone cover 1 of the upper component is sleeved on the twelve-petal mold 2 of the lower component, and an adjustment plate 5 is arranged between the lower end of the cone cover 1 and the upper end of the positioning edge 22 of the twelve-petal mold 2 to complete the assembly of the entire necking tooling;

[0051] S2, remove the upper component, remove the cone cover 1 from the twelve-petal mold 2, and the twelve petals 21 of the twelve-petal mold 2 expand radially outward under the action of the circumferential pre-compression spring 9; then place the rubber main spring 1' in the twelve-petal mold 2, and put the core shaft 12' of the rubber main spring 1' on the positioning pin 6, and the bottom end of the rubber main spring 1' contacts the top end of the lower pressing block 7;

[0052] S3, the lower end opening of the cone cover 1 of the upper component is placed on the twelve-petal mold 2, the bottom end of the upper pressing block 10 contacts the top end of the rubber main spring 1', and under the action of the axial pre-compression spring 11, the upper pressing block 10 applies pressure to the top end of the rubber main spring 1';

[0053] S4, the cone cover 1 is pressed down, and the twelve mold petals of the twelve-petal mold 2 are radially contracted inward to shrink the rubber main spring 1'; the necking amount can be changed by designing different thicknesses of the adjustment plate 5, and the compression amount of the upper and lower end surfaces of the rubber main spring can be achieved by designing different thicknesses of the adjustment sheet 12, and finally the purpose of preventing the cage and rubber from deforming in the window area of the rubber main spring is achieved;

[0054] S5, after the necking is in place, take off the upper component, remove the cone cover 1 from the twelve-petal mold 2, and the twelve mold petals 21 of the twelve-petal mold 2 expand radially outward under the action of the circumferential pre-compression spring 9, and then take out the rubber main spring 1' to complete the entire necking process of the rubber main spring.

[0055] The necking tooling for the rubber main spring of the hydraulic bushing of the present invention is mainly divided into upper and lower parts, which are connected by bolts or interference fit respectively. It is simple to process and convenient to operate. The necking tooling and the necking method have limiting mechanisms at both ends and the middle of the rubber main spring. Among them, the upper pressing block 10 and the lower pressing block 7 limit both ends of the rubber main spring, and the upper convex end face 213 and the lower convex end face 214 of the twelve-petal die 2 limit the middle of the rubber main spring. While realizing the necking process of the rubber main spring composed of the inner cage with a window, it can ensure that the inner cage and the rubber in the window area of the rubber main spring do not deform, and ensure the quality of the final hydraulic bushing product. The adjustable necking amount is realized by changing the thickness of the adjusting plate 5, and the compression amounts of the upper and lower end faces of the rubber main spring are adjustable by changing the thickness of the adjusting piece 12, so as to meet different trial production and production requirements. The upper pressing block 10 is installed with an axial pre-compression spring 11 to ensure that there is always a downward pressure on the upper and lower end faces of the rubber main spring during the necking process; the upper pressing block 10 and the adjusting piece 12 are adsorbed by a high-temperature magnet 15, which restricts the position of the adjusting piece 12 and ensures the stability of the structure during operation.

[0056] In summary, the necking tooling and the necking method for the rubber main spring of the hydraulic bushing of the present invention have limiting mechanisms at both ends and the middle of the rubber main spring, can realize the necking process of the rubber main spring composed of the inner cage with a window, and there is no deformation at the window end face and the middle after necking, the necking amount and the preloading amount are adjustable, and the operation is convenient.

[0057] Those of ordinary skill in the art in this technical field should recognize that the above embodiments are only used to illustrate the present invention, rather than to limit the present invention. As long as within the scope of the substantial spirit of the present invention, the changes and modifications of the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A necking method for the rubber main spring of a hydraulic bushing, characterized in that, Necking is carried out using a necking tooling. The necking tooling includes a base, a positioning pin, a lower pressing block, a twelve-petal die, a pressing plate, a conical cover, an upper pressing block, and an upper cover plate, where: A positioning pin mounting hole and a lower pressing block mounting hole are provided at the top of the base. The positioning pin mounting hole and the lower pressing block mounting hole are coaxially arranged, one inside the other, and the positioning pin mounting hole is located at the center of the base; The head of the positioning pin is press-fitted into the positioning pin mounting hole; The bottom end of the lower pressing block is press-fitted into the lower pressing block mounting hole; The twelve-petal die is composed of twelve die petals evenly distributed in the circumferential direction. Each die petal is formed by connecting a vertical part and a horizontal part in an L shape. An upward convex end face and a downward convex end face that protrude inward are provided on the inner wall surface of the vertical part of the die petal; A circumferential pre-compression spring is provided between every two adjacent die petals; The horizontal parts of the twelve die petals form the positioning edge of the twelve-petal die; The twelve-petal die is arranged at the top of the base, and all the twelve die petals are located outside the lower pressing block; The pressing plate is in a ring structure. The pressing plate is connected to the top of the base by bolts, and the pressing plate presses on the positioning edge of the twelve-petal die; The conical cover is in a conical shape with a smaller top and a larger bottom. The lower end opening of the conical cover is sleeved on the twelve-petal die, and an adjusting plate is provided between the lower end of the conical cover and the upper end of the positioning edge of the twelve-petal die; An annular inner convex platform that protrudes inward is provided on the inner wall of the upper end opening of the conical cover; The top end of the upper pressing block has an annular outer convex platform that protrudes outward. The upper pressing block is arranged in the upper end opening of the conical cover, and the annular outer convex platform is located above the annular inner convex platform; An axial blind hole and two magnet mounting holes are provided at the top end of the upper pressing block. The axial blind hole is located at the center of the upper pressing block; An axial pre-compression spring is arranged in the axial blind hole; A high-temperature magnet is arranged in each magnet mounting hole; The upper cover plate is connected to the top of the conical cover by bolts; An adjusting piece is provided between the bottom end of the upper cover plate and the top end of the upper pressing block, and the adjusting piece is adsorbed on the high-temperature magnet, The necking method includes the following steps: S1, Necking tooling assembly step, specifically including the following processes: S11, Lower component assembly process: Press-fit the head of the positioning pin into the positioning pin mounting hole of the base, and press-fit the bottom end of the lower pressing block into the lower pressing block mounting hole of the base; Then place the twelve-petal die on the top of the base, and a circumferential pre-compression spring is provided between every two adjacent die petals; Then connect the pressing plate to the base by bolts, and the pressing plate presses on the positioning edge of the twelve-petal die to complete the assembly of the lower components; S12, Upper component assembly process: Place an axial pre-compression spring in the axial blind hole at the center of the upper pressing block, and respectively arrange a high-temperature magnet in the two magnet mounting holes of the upper pressing block; Then place the upper pressing block in the upper end opening of the conical cover, place an adjusting piece on the top end of the upper pressing block, and then connect the upper cover plate to the top of the conical cover by bolts to complete the assembly of the upper components; Under the action of gravity, the annular outer convex platform of the upper pressing block overlaps on the annular inner convex platform of the conical cover; S13, sleeve the lower end opening of the cone cover of the upper component onto the twelve-petal mold of the lower component, and arrange an adjustment plate between the lower end of the cone cover and the upper end of the positioning edge of the twelve-petal mold to complete the assembly of the entire necking tooling; S2, remove the upper component, remove the cone cover from the twelve-petal mold, and the twelve petals of the twelve-petal mold expand radially outward under the action of the circumferential pre-compression spring; then place the rubber main spring in the twelve-petal mold, and sleeve the core shaft of the rubber main spring on the positioning pin, so that the bottom end of the rubber main spring contacts the top end of the lower pressing block; S3, the lower end opening of the cone cover of the upper component is placed on the twelve-petal mold, the bottom end of the upper pressing block contacts the top end of the rubber main spring, and under the action of the axial pre-compression spring, the upper pressing block applies pressure to the top end of the rubber main spring; S4, pressing the cone cover downward, so that the twelve mold petals of the twelve-petal mold are radially contracted inward to shrink the rubber main spring; S5, after the necking is in place, remove the upper assembly, remove the cone cover from the twelve-petal mold, and the twelve petals of the twelve-petal mold expand radially outward under the action of the circumferential pre-compression spring, and then take out the rubber main spring to complete the entire necking process of the rubber main spring.

2. The necking method of the rubber main spring of a hydraulic bushing according to claim 1, characterized in that, In the necking tooling, a spring mounting hole is provided on the vertical portion of each mold half, and the spring mounting holes of the twelve mold halves are distributed along the same circumference; the two ends of the circumferential pre-compression spring between each two adjacent mold halves are respectively located in the corresponding spring mounting holes.

3. A necking method for the rubber main spring of a hydraulic bushing as claimed in claim 1, characterized in that, In the necking tooling, the rubber main spring is arranged in the twelve-petal mold, the top end of the rubber main spring contacts the bottom end of the upper pressure block, the bottom end of the rubber main spring contacts the top end of the lower pressure block, and the tail end of the locating pin is inserted into the core shaft of the rubber main spring; the upper end surface of the window position of the rubber main spring is located above the upper convex end surface of the mold flap, and there is a gap of 0.2 to 0.5 mm between the two; the lower end surface of the window position of the rubber main spring is located below the lower convex end surface of the mold flap, and there is a gap of 0.2 to 0.5 mm between the two.

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