A valve stem manufacturing process

Abstract

The present application belongs to the technical field of valve stem precision manufacturing, and particularly relates to a valve stem manufacturing process. The valve stem manufacturing process provided by the present application adopts five-step axial cold extrusion step forming: S1, a cylindrical blank is extruded into a second blank with a lower end lower convex arc shape through a first die; S2, an arc necking section is formed through a second die, and a third blank with different upper and lower diameters is obtained; S3, a fourth blank with three sections of decreasing diameters is formed through twice taper necking of a third die; S4, the upper end is formed into an arc convex surface and a gradually expanding structure through extrusion of a fourth die, and a fifth blank is obtained; and S5, the target valve stem containing three stepped disc bodies and sunken tables, annular extended edges and other details is finally extruded through a fifth die. The valve stem manufacturing process of the present application controls material flow in steps, reasonably designs die cavity section structure to cooperatively control material flow, guarantees valve stem forming precision and quality, avoids stress concentration, and is suitable for batch production.

Description

Technical Field

[0001] This invention belongs to the field of precision valve stem manufacturing technology, and specifically relates to a valve stem manufacturing process. Background Technology

[0002] In hydraulic, pneumatic and other fluid control systems, the valve stem is a core precision component for realizing the opening and closing of the medium and the regulation of pressure. Its structure often integrates stepped discs and columns, and often has intricate and complex structures such as local recessed platforms and annular extended edges. It has stringent working conditions requirements for dimensional accuracy, surface roughness and structural strength.

[0003] Currently, the manufacturing of complex valve stems mainly relies on two types of processes. The first is machining, which involves multiple steps such as turning and milling to gradually form the stem. However, this process suffers from low material utilization and a cumbersome processing flow. Furthermore, for delicate structures such as small countersunk areas and thin-walled extended edges, it is prone to processing deformation and loss of precision control, making it difficult to adapt to large-scale mass production. The second is die extrusion molding, which has the advantages of high production efficiency and low material loss. However, it still faces many challenges in die cavity design and blank deformation planning. On the one hand, unreasonable cold extrusion of materials can easily cause local stress concentration, leading to forming defects such as tearing and surface scratches, and the dimensional deviation rate remains high. On the other hand, there is a compatibility problem between the die cavity structure and material flow planning, often resulting in local material distribution imbalances. For example, insufficient material allowance in some areas leads to incomplete forming of detailed structures such as countersunk areas and extended edges. In addition, poor local material flow and accumulation can cause surface unevenness and other defects, making it difficult to guarantee the size and quality of products during mass production.

[0004] Therefore, while ensuring production efficiency and material utilization, solving the problem of balancing dimensional accuracy, surface quality, and structural integrity in the forming process of complex valve stems has become a technological direction that urgently needs to be addressed in the field of precision valve stem manufacturing. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a valve stem manufacturing process.

[0006] The purpose of this invention is to solve, or at least partially solve, the problem of balancing dimensional accuracy, surface quality, and structural integrity in the molding process of complex valve stems.

[0007] The present invention first provides a valve stem forming mold, including a first mold, a second mold, a third mold, a fourth mold and a fifth mold used in sequence, for extruding a cylindrical first blank into a target valve stem part in steps;

[0008] The cavity of the first mold is used to form the second blank, and it includes a first cylindrical cavity section and an arc-shaped bottom cavity section from top to bottom. The bottom edge of the arc-shaped bottom cavity section has a downward convex arc-shaped structure.

[0009] The cavity of the second mold is used to form the third blank. It includes a second cylindrical cavity section, an arc-shaped necked cavity section and a third cylindrical cavity section from top to bottom. The bottom diameter of the second cylindrical cavity section is larger than the top diameter of the third cylindrical cavity section, and they are connected by the arc-shaped necked cavity section.

[0010] The cavity of the third mold is used to form the fourth blank, which includes, from top to bottom, a fourth cylindrical cavity segment, a first conical necked cavity segment, a fifth cylindrical cavity segment, a second conical necked cavity segment, and a sixth cylindrical cavity segment. The bottom diameter of the fourth cylindrical cavity segment is larger than the top diameter of the fifth cylindrical cavity segment, and the bottom diameter of the fifth cylindrical cavity segment is larger than the top diameter of the sixth cylindrical cavity segment.

[0011] The cavity of the fourth mold is used to form the fifth blank. From top to bottom, it includes an arc-shaped top cavity section, a first gradient cavity section, a third conical necking cavity section, a seventh cylindrical cavity section, a fourth conical necking cavity section, and an eighth cylindrical cavity section. The first gradient cavity section is a smooth transition cavity section whose diameter gradually increases from top to bottom.

[0012] The cavity shape of the fifth mold is complementary to the structure of the target valve stem and is used for final molding.

[0013] As a further optimization of any of the above valve stem forming dies, the fifth die cavity includes, from top to bottom, a first disc-shaped cavity segment, a second disc-shaped cavity segment, a third disc-shaped cavity segment, a ninth cylindrical cavity segment, and a conical bottom cavity segment; the diameters of the first disc-shaped cavity segment, the second disc-shaped cavity segment, and the third disc-shaped cavity segment decrease sequentially and are connected in a stepped manner; the diameter of the conical bottom cavity segment shrinks downward, and the top of the conical bottom cavity segment is smoothly connected to the bottom of the ninth cylindrical cavity segment.

[0014] As a further optimization of any of the above valve stem forming molds, the top center of the first disc-shaped cavity section is provided with a downward protruding cavity top boss, and the center of the cavity top boss is provided with a downward protruding first conical tip.

[0015] As a further optimization of any of the above valve stem forming molds, an annular edge groove is provided at the interface edge where the third disc-shaped cavity segment connects to the ninth column-shaped cavity segment.

[0016] As a further optimization of any of the above valve stem forming molds, the center of the conical bottom cavity section is provided with a second conical tip that protrudes upwards.

[0017] As a further optimization of any of the above valve stem forming molds, in the mold cavity of the first mold, the bottom edge of the first cylindrical cavity segment and the top edge of the arc-shaped bottom cavity segment are smoothly connected.

[0018] As a further optimization of any of the above valve stem forming molds, in the mold cavity of the second mold, the lower end of the second cylindrical cavity segment and the upper end of the arc-shaped necked cavity segment are smoothly connected, and the axes of the second cylindrical cavity segment and the third cylindrical cavity segment are kept coincident.

[0019] As a further optimization of any of the above valve stem forming molds, in the mold cavity of the third mold, both the first conical necking cavity section and the second conical necking cavity section have a downward contraction structure, and the edge generatrix is ​​a straight line.

[0020] As a further optimization of any of the above valve stem forming dies, in the cavity of the fourth die, the top edge of the arc-shaped top cavity section is an upwardly convex arc shape, and the bottom diameter of the arc-shaped top cavity section is consistent with the top diameter of the first gradient cavity section; the axes of the arc-shaped top cavity section, the first gradient cavity section, the third conical necking cavity section, the seventh cylindrical cavity section, the fourth conical necking cavity section, and the eighth cylindrical cavity section are kept coincident.

[0021] As a further optimization of any of the above valve stem forming dies, the first die, the second die, the third die, the fourth die, and the fifth die are all die structures for extrusion in the up-down direction; the cavity of the first die is formed by the cooperation of the lower die core, the upper punch, and the lower punch; the cavity of the second die is formed by the cooperation of the lower die core, the upper punch, and the lower punch; the cavity of the third die is formed by the cooperation of the upper die core, the lower die core, the upper punch, and the lower punch; the cavity of the fourth die is formed by the cooperation of the upper die core, the lower die core, the upper punch, and the lower punch; and the cavity of the fifth die is formed by the cooperation of the upper die core, the lower die core, and the lower punch.

[0022] The present invention further provides a valve stem manufacturing process, comprising the following steps:

[0023] S1: Provide a cylindrical first blank, place it in a first mold for extrusion, and shape the lower end of the first blank into a structure with a downwardly convex arc surface to obtain a second blank;

[0024] S2: The second blank is placed in the second mold for extrusion, forming an arc-shaped necking section on its column, so that the upper diameter of the blank in the necking section is larger than the lower diameter, thus obtaining the third blank.

[0025] S3: The third blank is placed in the third mold and extruded to form a tapered necking deformation from top to bottom, forming a stepped columnar structure with three sections of decreasing diameter from top to bottom, thus obtaining the fourth blank;

[0026] S4: The fourth blank is placed in the fourth mold and extruded to form the upper part of the fourth blank into a transition structure with an arc-shaped convex surface on the periphery and a diameter that gradually expands from top to bottom, thus obtaining the fifth blank.

[0027] S5: The fifth blank is placed in the fifth mold for final extrusion, shaping it into a target valve stem that includes an upper three-tiered disc structure and a lower columnar structure.

[0028] As a further optimization of any of the above valve stem manufacturing processes, in step S1, the mold cavity of the first mold includes a first cylindrical cavity section and an arc-shaped bottom cavity section from top to bottom. The bottom edge of the first cylindrical cavity section and the top edge of the arc-shaped bottom cavity section are smoothly connected. Extrusion causes the lower end of the first blank to form a second blank with a convex arc bottom edge in the arc-shaped bottom cavity section.

[0029] As a further optimization of any of the above valve stem manufacturing processes, in step S2, the mold cavity of the second mold includes, from top to bottom, a second cylindrical cavity segment, an arc-shaped necked cavity segment, and a third cylindrical cavity segment. The bottom diameter of the second cylindrical cavity segment is larger than the top diameter of the third cylindrical cavity segment, and they are connected by the arc-shaped necked cavity segment. Extrusion causes the middle part of the second blank to be formed in the arc-shaped necked cavity segment, forming a third blank with two cylindrical sections of different diameters at the top and bottom, which are smoothly connected by the arc-shaped neck.

[0030] As a further optimization of any of the above valve stem manufacturing processes, in step S3, the mold cavity of the third mold includes, from top to bottom, a fourth cylindrical cavity segment, a first conical necking cavity segment, a fifth cylindrical cavity segment, a second conical necking cavity segment, and a sixth cylindrical cavity segment. The bottom diameter of the fourth cylindrical cavity segment is larger than the top diameter of the fifth cylindrical cavity segment, and the bottom diameter of the fifth cylindrical cavity segment is larger than the top diameter of the sixth cylindrical cavity segment. Through the two conical necking transitions of the first and second conical necking cavity segments, the blank is formed into a three-section cylindrical structure.

[0031] As a further optimization of any of the above valve stem manufacturing processes, in step S4, the cavity of the fourth mold includes, from top to bottom, an arc-shaped top cavity section, a first gradient cavity section, a third conical necking cavity section, a seventh cylindrical cavity section, a fourth conical necking cavity section, and an eighth cylindrical cavity section. The first gradient cavity section is a smooth transition cavity section whose diameter gradually increases from top to bottom. Extrusion causes the upper end of the blank to be formed into a top arc-shaped protrusion and a gradually expanding structure within the arc-shaped top cavity section and the first gradient cavity section.

[0032] As a further optimization of any of the above valve stem manufacturing processes, in step S5, the cavity structure of the fifth mold is complementary to the structure of the target valve stem. The cavity of the fifth mold includes, from top to bottom, a first disc-shaped cavity segment, a second disc-shaped cavity segment, a third disc-shaped cavity segment, a ninth cylindrical cavity segment, and a conical bottom cavity segment. The diameters of the first disc-shaped cavity segment, the second disc-shaped cavity segment, and the third disc-shaped cavity segment decrease sequentially and are connected in a stepped manner. The diameter of the conical bottom cavity segment shrinks downward, and the top of the conical bottom cavity segment is smoothly connected to the bottom of the ninth cylindrical cavity segment.

[0033] As a further optimization of any of the above valve stem manufacturing processes, the target valve stem comprises, from top to bottom, a first disc, a second disc, a third disc, a first column, and a first frustum; wherein, the diameters of the first disc, the second disc, and the third disc decrease sequentially and are connected in a stepped manner, a recessed platform is formed at the center of the top of the first disc and a first conical recess located at the center of the platform, a downwardly convex annular extension edge is formed at the interface edge connecting the third disc and the first column, and a second conical recess is formed at the center of the bottom of the first frustum.

[0034] As a further optimization of any of the above valve stem manufacturing processes, the top center of the first disc-shaped cavity section is provided with a cavity top boss for forming a recessed platform, and the center of the cavity top boss is provided with a first conical tip for forming a first conical depression; the center of the conical bottom cavity section is provided with a second conical tip for forming a second conical depression.

[0035] As a further optimization of any of the above valve stem manufacturing processes, the edge of the connection interface between the third disc-shaped cavity segment and the ninth column-shaped cavity segment is provided with an edge groove for forming an annular extended edge.

[0036] As a further optimization of any of the above valve stem manufacturing processes, the extrusion in each step is a cold extrusion along the axial direction of the blank.

[0037] Beneficial effects

[0038] Compared with existing technologies, the valve stem forming mold of the present invention achieves precise adaptation between the mold cavity structure and the blank deformation process through the step-by-step and coordinated use of five sets of molds. From the arc-shaped bottom cavity section of the first mold gently guiding the initial deformation of the material to avoid stress concentration, to the two conical necking cavity sections of the third mold decompose the dimensional difference to improve precision control, and then to the multi-disc cavity section and detailed cavity structure of the fifth mold that are completely complementary to the target valve stem to support the material distribution of the previous sequence, the cavity morphology of each mold is coherent and coordinated, gradually controlling the material flow and progressively shaping the structural form. This not only solves the problems of dimensional deviation and surface scratches, but also allows the complex local structures of the target valve stem, such as the stepped disc, recessed platform, and annular extended edge, to be precisely formed. Ultimately, it ensures the dimensional accuracy, surface quality, and structural strength of the valve stem after forming, and solves the problem that existing technical solutions cannot simultaneously ensure the integrity of details and the reliability of forming in the forming of complex valve stem structures.

[0039] In the valve stem manufacturing process, the arc-shaped bottom structure forming in step S1 provides material flow margin for subsequent necking deformation. The three-segment columnar structure shaping in step S3 lays the foundation for material distribution in the top plate. The final extrusion in step S5 relies on the accumulation of previous gradient deformation to achieve stress-free forming of complex details. Each step works together to form a unique deformation process, gradually controlling material flow and progressively shaping the structural form. This avoids defects such as material tearing and stress concentration caused by a single intense extrusion. Furthermore, the refined adjustment of the blank shape at each step improves the dimensional consistency of products in mass production. At the same time, while ensuring the complete forming of the complex functional structure of the valve stem, it reduces the forming defect rate and subsequent processing costs, giving it the dual advantages of high production efficiency and stable quality. Attached Figure Description

[0040] Figure 1 This is a flowchart of the valve stem manufacturing process.

[0041] Figure 2 This is a schematic diagram of the structure of the first mold.

[0042] Figure 3 This is a schematic diagram of the second mold.

[0043] Figure 4 This is a schematic diagram of the third mold.

[0044] Figure 5 This is a schematic diagram of the fourth mold.

[0045] Figure 6 This is a schematic diagram of the fifth mold.

[0046] Figure 7 This is a cross-sectional schematic diagram of the first mold cavity.

[0047] Figure 8 This is a cross-sectional schematic diagram of the second mold cavity.

[0048] Figure 9 This is a cross-sectional schematic diagram of the third mold cavity.

[0049] Figure 10 This is a cross-sectional schematic diagram of the fourth mold cavity.

[0050] Figure 11 This is a cross-sectional schematic diagram of the fifth mold cavity.

[0051] Figure 12 A schematic diagram of the structure of the target valve stem component.

[0052] In the diagram, 1 is the first mold; 2 is the second mold; 3 is the third mold; 4 is the fourth mold; and 5 is the fifth mold.

[0053] 91. First blank; 92. Second blank; 93. Third blank; 94. Fourth blank; 95. Fifth blank; 96. Target valve stem;

[0054] 81. First disc; 82. Second disc; 83. Third disc; 84. First column; 85. First frustum; 811. Settlement; 812. First conical recess; 851. Second conical recess; 831. Extended edge;

[0055] 11. First cylindrical cavity segment; 12. Arc-shaped bottom cavity segment;

[0056] 21. Second cylindrical cavity segment; 22. Arc-shaped constricted cavity segment; 23. Third cylindrical cavity segment;

[0057] 31. Fourth cylindrical cavity segment; 32. First conical constricted cavity segment; 33. Fifth cylindrical cavity segment; 34. Second conical constricted cavity segment; 35. Sixth cylindrical cavity segment;

[0058] 41. Arc-shaped apex cavity segment; 42. First gradually changing cavity segment; 43. Third conical constricted cavity segment; 44. Seventh cylindrical cavity segment; 45. Fourth conical constricted cavity segment; 46. Eighth cylindrical cavity segment;

[0059] 51. First disc-shaped cavity segment; 52. Second disc-shaped cavity segment; 53. Third disc-shaped cavity segment; 54. Ninth columnar cavity segment; 55. Conical bottom cavity segment; 511. Cavity top protrusion; 512. First conical protrusion; 551. Second conical protrusion; 531. Edge groove. Detailed Implementation

[0060] The present invention is further illustrated below through embodiments, which are intended to more clearly illustrate the technical solutions of the present invention, and should not be construed as a limitation.

[0061] like Figures 1 to 6 As shown, the complete valve stem forming mold set includes a first mold 1, a second mold 2, a third mold 3, a fourth mold 4, and a fifth mold 5, which are used both as a set and for single-use applications. A cylindrical first blank 91 is extruded through the first mold 1 to obtain a second blank 92. The second blank 92 is extruded through the second mold 2 to obtain a third blank 93. The third blank 93 is extruded through the third mold 3 to obtain a fourth blank 94. The fourth blank 94 is extruded through the fourth mold 4 to obtain a fifth blank 95. The fifth blank 95 is extruded through the fifth mold 5 to obtain the target valve stem 96. The cavity shapes in each mold are as follows: Figures 7 to 11 As shown, where, Figure 7 The image shows the shape of the mold cavity formed after the first mold 1 has finished extruding. Figure 8 The image shows the shape of the mold cavity formed after extrusion by the second mold 2. Figure 9 The image shows the shape of the mold cavity formed after the third mold 3 has finished extruding. Figure 10 The image shows the shape of the mold cavity formed after extrusion by the fourth mold 4. Figure 11 The diagram shows the shape of the mold cavity formed after extrusion using the fifth mold 5. Corresponding to the mold cavity of the fifth mold 5, the shape of the resulting target valve stem 96 is as follows: Figure 12 As shown.

[0062] like Figures 2 to 6 As shown, the first mold 1, the second mold 2, the third mold 3, the fourth mold 4, and the fifth mold 5 are all assembled from basic upper and lower mold cores and upper and lower punches. Among them, as... Figure 2 As shown, the first mold 1 is formed by the cooperation of the lower mold core, the upper punch, and the lower punch. Figure 7 The mold cavity shape shown; such as Figure 3 As shown, the second mold 2 is formed by the cooperation of the lower mold core, the upper punch, and the lower punch. Figure 8 The mold cavity shape shown; such as Figure 4 As shown, the third mold 3 is formed by the cooperation of an upper mold core, a lower mold core, an upper punch, and a lower punch. Figure 9 The mold cavity shape shown; such as Figure 5 As shown, the fourth mold 4 is formed by the cooperation of an upper mold core, a lower mold core, an upper punch, and a lower punch. Figure 10 The mold cavity shape shown; such as Figure 6 As shown, the fifth mold 5 is formed by the cooperation of the upper mold core, the lower mold core, and the lower punch. Figure 11 The shape of the mold cavity is shown.

[0063] like Figure 7 As shown, the mold cavity formed after the first mold 1 is extruded is cylindrical in shape, and from top to bottom it includes a first cylindrical cavity segment 11 and an arc-shaped bottom cavity segment 12. The bottom diameter of the first cylindrical cavity segment 11 is equal to the top diameter of the arc-shaped bottom cavity segment 12, and the two are smoothly connected at the joint. The bottom edge of the arc-shaped bottom cavity segment 12 has a downwardly convex semi-circular arc structure.

[0064] like Figure 8 As shown, the mold cavity formed after the second mold 2 is extruded is cylindrical in shape, and from top to bottom includes a second cylindrical cavity segment 21, an arc-shaped constricted cavity segment 22, and a third cylindrical cavity segment 23. The bottom diameter of the second cylindrical cavity segment 21 is larger than the top diameter of the third cylindrical cavity segment 23. The two are smoothly connected by the inwardly constricted arc-shaped constricted cavity segment 22, and the axes of the second cylindrical cavity segment 21 and the third cylindrical cavity segment 23 are aligned.

[0065] like Figure 9As shown, the mold cavity formed after the third mold 3 is extruded is cylindrical in shape, and from top to bottom includes a fourth cylindrical cavity segment 31, a first conical necked cavity segment 32, a fifth cylindrical cavity segment 33, a second conical necked cavity segment 34, and a sixth cylindrical cavity segment 35. The bottom diameter of the fourth cylindrical cavity segment 31 is larger than the top diameter of the fifth cylindrical cavity segment 33, and the two are connected by the first conical necked cavity segment 32, which tapers inward. The bottom diameter of the fifth cylindrical cavity segment 33 is larger than the top diameter of the sixth cylindrical cavity segment 35, and the two are connected by the second conical necked cavity segment 34, which also tapers inward. Furthermore, the axes of the fourth cylindrical cavity segment 31, the fifth cylindrical cavity segment 33, and the sixth cylindrical cavity segment 35 are collinear.

[0066] like Figure 10 As shown, the mold cavity formed after the fourth mold 4 is extruded is cylindrical in shape, and from top to bottom includes an arc-shaped top cavity section 41, a first gradient cavity section 42, a third conical necking cavity section 43, a seventh cylindrical cavity section 44, a fourth conical necking cavity section 45, and an eighth cylindrical cavity section 46. Among them, the top edge of the arc-shaped top cavity section 41 is an upwardly convex arc shape, and the bottom diameter of the arc-shaped top cavity section 41 is the same as the top diameter of the first gradient cavity section 42. The first gradient cavity section 42 is a smooth transition cavity section with a gradually increasing diameter from top to bottom. The bottom of the first gradient cavity section 42 is connected to the seventh cylindrical cavity section 44 through the third conical necking cavity section 43. The seventh cylindrical cavity section 44 is then connected to the eighth cylindrical cavity section 46 with a smaller diameter through the fourth conical necking cavity section 45, and the axes of each cavity section are kept coincident.

[0067] like Figure 11 As shown, the shape of the mold cavity formed after the fifth mold 5 is extruded corresponds to the shape of the target valve stem 96, and from top to bottom includes a first disc-shaped cavity segment 51, a second disc-shaped cavity segment 52, a third disc-shaped cavity segment 53, a ninth cylindrical cavity segment 54, and a conical bottom cavity segment 55. The first disc-shaped cavity segment 51 has a downward-protruding cavity top boss 511 at its top center, and a downward-protruding first conical tip 512 on the cavity top boss 511. The conical bottom cavity segment 55 has an upward-protruding second conical tip 551 at its center. The third disc-shaped cavity segment 53 has an annular edge groove 531 at its edge. The diameter of the first disc-shaped cavity segment 51 is larger than that of the second disc-shaped cavity segment 52, and the two are connected in a stepped manner with a smooth transition at the connection point; the diameter of the second disc-shaped cavity segment 52 is larger than that of the third disc-shaped cavity segment 53, and the two are connected in a stepped manner with a smooth transition at the connection point; the diameter of the third disc-shaped cavity segment 53 is larger than that of the ninth columnar cavity segment 54, and at the interface connecting the third disc-shaped cavity segment 53 and the ninth columnar cavity segment 54, the edge of the third disc-shaped cavity segment 53 is recessed downward to form an annular recessed structure, that is, to form an edge groove 531, and the groove wall of the edge groove 531 transitions perpendicularly to the main cavity wall of the third disc-shaped cavity segment 53; the bottom of the ninth columnar cavity segment 54 is smoothly connected to the top of the conical bottom cavity segment 55.

[0068] Figure 12 The target valve stem 96 shown has a shape similar to Figure 11 The fifth mold 5 corresponds to the mold cavity, which, from top to bottom, includes a first disc 81, a second disc 82, a third disc 83, a first pillar 84, and a first frustum 85. Specifically, the first disc 81 has an inwardly recessed platform 811 at its top center; the platform 811 has a first conical protrusion 512 at its center, forming a first conical recess 812; the diameter of the first disc 81 is larger than the diameter of the second disc 82, and the two are connected in a stepped manner with a smooth transition at the connection point; the diameter of the second disc 82 is larger than the diameter of the third disc 83, and they are also connected in a stepped manner with a smooth transition at the connection point; the diameter of the third disc 83 is larger than the diameter of the first pillar 84, and the two are connected in a stepped manner, with a downwardly protruding annular extension edge 831 forming at the interface between them; the bottom of the first pillar 84 is smoothly connected to the top of the first frustum 85, and the bottom center of the first frustum 85 has an inwardly recessed second conical recess 851.

[0069] like Figure 11 and Figure 12 As shown, the cavity structure of the fifth mold 5 is completely complementary to the structure of the target valve stem 96. The first disc-shaped cavity segment 51, the second disc-shaped cavity segment 52, the third disc-shaped cavity segment 53, the ninth cylindrical cavity segment 54, and the conical bottom cavity segment 55 of the mold cavity provide forming space for the first disc body 81, the second disc body 82, the third disc body 83, the first cylindrical body 84, and the first conical body 85 of the target valve stem 96, respectively. The diameter of each cavity segment and the stepped, smooth transition connection method directly determine the size ratio and connection form of the corresponding parts of the valve stem; The top boss 511 and the first conical tip 512 of the first disc-shaped cavity section 51 form the valve stem countersunk 811 and the first conical recess 812 of the blank through extrusion. The edge groove 531 of the third disc-shaped cavity section 53 allows the blank to form an outwardly protruding annular extension edge 831 during forming. The second conical tip 551 of the conical bottom cavity section 55 corresponds to the second conical recess 851 of the formed valve stem. This correspondence allows the blank to accurately replicate all the structural details of the target valve stem 96 after extrusion, thereby efficiently and reliably forming the target valve stem 96.

[0070] The aforementioned complete valve stem forming die set employs a five-die step-by-step extrusion method to form the blank into the target valve stem component 96. This gradual extrusion design addresses issues such as difficulty in controlling dimensional accuracy, poor surface quality, and uneven material flow in existing valve stem forming processes by progressively adjusting the blank's structural morphology and precisely controlling the material flow at different stages. The following section will elaborate on the role of each step of the gradual process in the reliable forming of the final target valve stem component 96, taking into account the changes in the blank's structure at each die stage.

[0071] The cylindrical first blank 91 is extruded by the first mold 1 to form the second blank 92. This process achieves a gradual transition from a pure cylindrical structure to a semi-circular bottom structure. The mold cavity of the first mold 1 consists of a first cylindrical cavity section 11 and an arc-shaped bottom cavity section 12. The bottom and top diameters of the two are equal and smoothly transitioned. The bottom edge of the arc-shaped bottom cavity section 12 is a downward-convex semi-circular arc. This gradual design can avoid stress concentration during the initial extrusion, making the initial deformation of the material smoother. It effectively prevents local material tearing caused by a right angle or planar structure at the bottom, ensuring the surface quality of the blank in the early stage. At the same time, the arc-shaped transition structure can also guide the material to flow evenly, reducing the generation of forming defects such as dents and burrs.

[0072] The second blank 92 is extruded by the second mold 2 to obtain the third blank 93. Structurally, the overall structure gradually changes from a single, continuous section to a two-section connected structure with different diameters at the top and bottom. Specifically, the mold cavity of the second mold 2 consists of, from top to bottom, a second cylindrical cavity section 21, an arc-shaped necking cavity section 22, and a third cylindrical cavity section 23. The bottom diameter of the second cylindrical cavity section 21 is larger than the top diameter of the third cylindrical cavity section 23. They are smoothly connected by the inwardly contracting arc-shaped necking cavity section 22, and their axes coincide. Compared to right-angle necking, arc-shaped necking significantly reduces abrupt changes in material flow, ensuring uniform deformation at the necking point, avoiding local accumulation or thinning, improving the dimensional accuracy of the necking area, reducing frictional scratches between the material and the mold cavity, and further optimizing the surface quality of the blank.

[0073] The third blank 93 is extruded by the third mold 3 to form the fourth blank 94. Two tapered necking operations achieve step-by-step diameter adjustment, completing the gradual transition of the roughly three-segment cylindrical structure. The mold cavity of the third mold 3 includes a fourth cylindrical cavity segment 31, a first tapered necking cavity segment 32, a fifth cylindrical cavity segment 33, a second tapered necking cavity segment 34, and a sixth cylindrical cavity segment 35. The axes of each cylindrical cavity segment are collinear, and the diameter is gradually reduced through the tapered necking cavity segments. This step-by-step necking is a crucial step in first forming the three-level structure and then further shaping it in subsequent steps. By decomposing the large dimensional difference into two small-amplitude deformations, it avoids diameter deviations caused by excessive single deformation, significantly improving the controllability of dimensional accuracy. Simultaneously, the tapered transition structure guides the material to flow smoothly towards the necking point, avoiding localized stress concentration, and also reserves appropriate material allowance for the subsequent connection between the column and the disc, laying the foundation for subsequent forming.

[0074] The fourth blank 94 is extruded through the fourth die 4 to obtain the fifth blank 95. This mainly involves refining the top stage of the three-tiered structure of the fourth blank 94 formed by the third die 3, shortening the length-to-diameter ratio of the top stage to create a fine gradient between the top diameter expansion and the columnar section. The mold cavity of the fourth die 4, from top to bottom, consists of an arc-shaped top cavity section 41, a first gradient cavity section 42, a third conical necking cavity section 43, a seventh columnar cavity section 44, a fourth conical necking cavity section 45, and an eighth columnar cavity section 46. The top of the arc-shaped top cavity section 41 is arc-shaped, and the diameter of the first gradient cavity section 42 gradually increases from top to bottom, with the axes of each cavity section coinciding. The gradient diameter expansion cavity section makes the material generally form a regular columnar shape and concentrates more in the lower position, providing sufficient material for the stepped disc structure at the top of the target valve stem 96, effectively solving the problem of surface or bulk forming defects caused by insufficient local material distribution.

[0075] The fifth blank 95 is finally formed into the target valve stem 96 by extrusion through the fifth mold 5. Through the cooperation of multiple disc-shaped cavity segments and detailed cavity structures, the precise forming of complex details such as the disc body, the sinking structure, and the extension structure is achieved. Specifically, the mold cavity of the fifth mold 5 is completely complementary to the structure of the target valve stem 96. From top to bottom, it includes the first disc-shaped cavity segment 51, the second disc-shaped cavity segment 52, the third disc-shaped cavity segment 53, the ninth columnar cavity segment 54, and the conical bottom cavity segment 55. The diameter of each disc-shaped cavity segment gradually decreases and has a smooth step transition. The cavity also has detailed structures such as the cavity top boss 511, the first conical protrusion 512, the edge groove 531, and the second conical protrusion 551. Since the material has been properly allocated and gradually deformed in the previous four stages, the extrusion in the fifth stage does not need to withstand severe deformation. This allows the local details such as the recessed platform 811, the first conical depression 812, the annular extended edge 831, and the second conical depression 851 to be formed completely, solving the problem of difficult forming of complex local structures. It also avoids surface cracks and dimensional deviations caused by severe deformation, ultimately ensuring that the strength, surface quality, and dimensional accuracy of the target valve stem 96 all meet the design requirements.

[0076] Based on the five-part step-by-step molding process described above, a complete valve stem manufacturing process can be formed, which specifically includes the following steps:

[0077] Step S1: Take the first cylindrical blank 91, place it in the first mold 1 to complete the extrusion process, and obtain the second blank 92 with a semi-circular arc structure at the bottom;

[0078] Step S2: Transfer the second blank 92 into the second mold 2 for extrusion to obtain the third blank 93, which has two sections with an arc-shaped necked connecting section in the middle.

[0079] Step S3: Place the third blank 93 into the third mold 3 and extrude it to obtain the fourth blank 94 with a three-section cylindrical structure;

[0080] Step S4: Place the fourth blank 94 into the fourth mold 4 to complete the top diameter expansion and extrusion gradient adjustment to form the fifth blank 95;

[0081] Step S5: Place the fifth blank 95 into the fifth mold 5 for final extrusion to precisely form the target valve stem 96 with detailed structures such as disc and sink.

[0082] The aforementioned valve stem manufacturing process cleverly decomposes the forming of complex and intricately structured valve stems into a series of deformation processes through multi-stage progressive extrusion. This process precisely controls the shape and material distribution of the blank at each extrusion step, avoiding stress concentration and material tearing caused by a single, drastic deformation. Furthermore, the connection between each step provides a suitable structural foundation and material allowance for subsequent forming. Ultimately, while ensuring the stability of material flow, this process efficiently achieves the precise forming of complex local structures in the valve stem, and also significantly improves the dimensional accuracy, surface quality, and forming consistency of the product.

[0083] The above embodiments are exemplary and are intended to illustrate the technical concept and features of the present invention, so that those skilled in the art can understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A valve stem manufacturing process characterized by, The method comprises the following steps: S1: providing a first blank (91) in a cylindrical shape, and placing the first blank (91) in a first mold (1) for extrusion to form a lower end of the first blank (91) into a structure with a lower convex arc surface, to obtain a second blank (92); S2: placing the second blank (92) in a second mold (2) for extrusion to form an arc necking section on the cylinder, so that the diameter of the blank at the upper part of the necking section is greater than the diameter at the lower part, to obtain a third blank (93); S3: placing the third blank (93) in a third mold (3) for extrusion to form a two-time taper necking deformation from top to bottom, to form a stepped cylinder structure with three sections of diameters decreasing from top to bottom, to obtain a fourth blank (94); S4: placing the fourth blank (94) in a fourth mold (4) for extrusion to form an upper part of the fourth blank (94) into a transition structure with an arc convex surface on the side and a diameter gradually expanding from top to bottom, to obtain a fifth blank (95); S5: placing the fifth blank (95) in a fifth mold (5) for final extrusion to form the fifth blank (95) into a target valve stem piece (96) containing a three-step disc structure at the upper part and a cylindrical structure at the lower part.

2. The valve stem manufacturing process of claim 1, wherein, In step S1, the mold cavity of the first mold (1) comprises a first cylindrical cavity section (11) and an arc bottom cavity section (12) from top to bottom, the bottom edge of the first cylindrical cavity section (11) is smoothly connected with the top edge of the arc bottom cavity section (12), and extrusion causes the lower end of the first blank (91) to form the second blank (92) with a lower convex circular arc bottom edge in the arc bottom cavity section (12).

3. The valve stem manufacturing process of claim 1, wherein, In step S2, the mold cavity of the second mold (2) comprises a second cylindrical cavity section (21), an arc necking cavity section (22) and a third cylindrical cavity section (23) from top to bottom, the bottom diameter of the second cylindrical cavity section (21) is greater than the top diameter of the third cylindrical cavity section (23), and the second cylindrical cavity section (21) is connected with the third cylindrical cavity section (23) through the arc necking cavity section (22); extrusion causes the middle part of the second blank (92) to be formed in the arc necking cavity section (22) to form the third blank (93) with a cylinder with different diameters at the upper part and the lower part and smoothly connected through an arc neck.

4. The valve stem manufacturing process of claim 1, wherein, In step S3, the mold cavity of the third mold (3) comprises a fourth cylindrical cavity section (31), a first taper necking cavity section (32), a fifth cylindrical cavity section (33), a second taper necking cavity section (34) and a sixth cylindrical cavity section (35) from top to bottom, the bottom diameter of the fourth cylindrical cavity section (31) is greater than the top diameter of the fifth cylindrical cavity section (33), and the bottom diameter of the fifth cylindrical cavity section (33) is greater than the top diameter of the sixth cylindrical cavity section (35); the blank is formed into a three-section cylinder structure through the two-time taper necking transitions of the first taper necking cavity section (32) and the second taper necking cavity section (34).

5. The valve stem manufacturing process of claim 1, wherein, In step S4, the cavity of the fourth die (4) comprises, from top to bottom, an arc-shaped top cavity section (41), a first gradually-changing cavity section (42), a third tapered neck cavity section (43), a seventh cylindrical cavity section (44), a fourth tapered neck cavity section (45), and an eighth cylindrical cavity section (46). The first gradually-changing cavity section (42) is a smooth transition cavity section with gradually increasing diameter from top to bottom. Extrusion causes the upper end of the blank to be shaped into a top arc-shaped protrusion and a gradually expanding structure in the arc-shaped top cavity section (41) and the first gradually-changing cavity section (42).

6. The valve stem manufacturing process of claim 1, wherein, In step S5, the cavity structure of the fifth die (5) is complementary to the structure of the target valve stem piece (96). The cavity of the fifth die (5) comprises, from top to bottom, a first disc-shaped cavity section (51), a second disc-shaped cavity section (52), a third disc-shaped cavity section (53), a ninth cylindrical cavity section (54), and a tapered bottom cavity section (55). The diameters of the first disc-shaped cavity section (51), the second disc-shaped cavity section (52), and the third disc-shaped cavity section (53) decrease in turn and are connected in a stepped manner. The diameter of the tapered bottom cavity section (55) shrinks downward, and the top of the tapered bottom cavity section (55) is smoothly connected to the bottom of the ninth cylindrical cavity section (54).

7. The valve stem manufacturing process of claim 6, wherein, The target valve stem piece (96) comprises, from top to bottom, a first disc body (81), a second disc body (82), a third disc body (83), a first cylindrical body (84), and a first frustum body (85). The diameters of the first disc body (81), the second disc body (82), and the third disc body (83) decrease in turn and are connected in a stepped manner. A sunken platform (811) is formed in the center of the top of the first disc body (81), and a first tapered recess (812) is formed in the center of the sunken platform (811). An annular extended edge (831) is formed on the interface edge between the third disc body (83) and the first cylindrical body (84). A second tapered recess (851) is formed in the center of the bottom of the first frustum body (85).

8. The valve stem manufacturing process of claim 7, wherein, A cavity top boss (511) for forming the sunken platform (811) is provided in the center of the top of the first disc-shaped cavity section (51). A first tapered protruding tip (512) for forming the first tapered recess (812) is provided in the center of the cavity top boss (511). A second tapered protruding tip (551) for forming the second tapered recess (851) is provided in the center of the tapered bottom cavity section (55).

9. The valve stem manufacturing process of claim 7, wherein, An edge sunken groove (531) for forming the annular extended edge (831) is provided on the connection interface edge between the third disc-shaped cavity section (53) and the ninth cylindrical cavity section (54).

10. The valve stem manufacturing process of any one of claims 1-9, wherein, In each step, the extrusion is cold extrusion along the axis of the blank.

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