Cold extrusion forming method for valve seat

Abstract

The invention discloses a valve seat cold extrusion forming method, and relates to the technical field of valve seat machining method.The forming steps include S1, end face finishing and chamfering pre-forming, specifically, the end face of a blank is leveled, and pressure is applied to the end face through a first upper punching rod to form a pre-formed chamfer; s2, head guide hole angle pre-forming and inclined chamfer forming are conducted, a guide hole angle structure is formed in the center area of the head of the blank through a first upper punching rod, and meanwhile an inclined chamfer is formed at the bottom of the blank through cooperation of a first lower punching rod and a mold; and S3, pre-stretching hole backward extrusion and bottom chamfering are carried out, the hole guiding angle structure is extruded through a second upper punching rod to form a pre-stretching hole, and the material is guided through the mold to flow in the inclined chamfering direction so as to optimize the shape of the bottom chamfering. The valve seat has the effect of effectively reducing the possibility that a folding layer appears at the root of the valve seat hole.

Description

Technical Field

[0001] The present invention relates to the technical field of valve seat processing methods, in particular to a valve seat cold extrusion molding method. Background Art

[0002] The valve seat is a crucial mechanical component in new energy thermal management systems. Its primary function is to control the flow direction, volume, and pressure of cooling media (such as coolant and refrigerant). As the core structural unit of the valve assembly, the quality of the valve seat is crucial to system performance and must be leak-free during operation.

[0003] However, during the traditional cold extrusion process of valve seats, material deformation and mechanical stress, coupled with improper die design for guide angles and fillet radii, can exacerbate uneven material flow and stress concentration, leading to the formation of folds at the base of the valve seat hole. These folds can gradually develop into cracks during subsequent use, affecting the sealing and overall performance of the valve seat. Summary of the Invention

[0004] The present application provides a valve seat cold extrusion molding method, which has the effect of effectively reducing the possibility of a folding layer appearing at the root of the valve seat hole.

[0005] This application provides a valve seat cold extrusion molding method, which adopts the following technical solutions: A valve seat cold extrusion molding method, the molding steps comprising: S1: End surface finishing and pre-forming chamfering, the end surface of the blank is leveled, and a first upper punch is used to apply pressure to the end surface to form a pre-forming chamfer; S2: Pre-forming of the hole angle and chamfering of the head: a hole angle structure is formed in the center area of ​​the head of the blank by a first upper punch, and a chamfer is formed at the bottom of the blank by a first lower punch in cooperation with a die; S3: Pre-pull hole reverse extrusion and bottom chamfering, using a second upper punch to extrude the hole guide angle structure to form a pre-pull hole, and guiding the material to flow along the oblique chamfer direction through the die to optimize the bottom chamfer shape; S4: flange pre-forming and inner hole pre-stretching: the upper end of the blank is squeezed by the third upper punch to form a flange prototype, and the pre-stretched hole is expanded by the second lower punch to form a pre-stretched inner hole; S5: final flange forming and inner hole drawing, the flange prototype is formed into a final flange contour by the cooperative extrusion of the fourth upper punch rod and the third lower punch rod, and the pre-stretched inner hole is further stretched by the cooperation of the fourth upper punch rod and the third lower punch rod to form a final inner hole; S6: Punching out waste materials, punching out waste materials at the connection between the flange and the pre-drawn hole by a fifth upper punch rod.

[0006] By adopting the above technical solution, the cold extrusion forming method of the valve seat shows significant advantages by finely controlling the deformation of the blank through six steps. S1 ensures that the end face of the blank is flat, laying the foundation for subsequent forming. S2 and S3 cleverly pre-form the lead hole angle and pre-pull hole to prepare for the final forming of the inner hole, while optimizing the bottom chamfer shape. In the S4 and S5 stages, the flange pre-forming and final forming are carried out simultaneously with the pre-stretching and pulling of the inner hole, realizing precise control of the flange profile and inner hole size. Finally, the S6 step cleanly flushes out the waste to ensure the integrity of the product. The entire process does not require heating, and the material utilization rate is high. The staged forming strategy effectively reduces the forming force. Combined with the pre-pull hole back extrusion and bottom chamfering, it can effectively reduce the possibility of a folding layer at the root of the valve seat hole and extend the mold life.

[0007] Preferably, in S1, the preformed chamfer is a conical structure with the top inclined inward, and the taper of the conical structure and the angle between the end face of the blank are in the range of 15°-45°.

[0008] By adopting the above technical solution, the conical pre-formed chamfer range optimizes material flow and avoids stress concentration and cracking; this design guides the material to deform evenly, reduces the difficulty of subsequent extrusion, and improves forming quality.

[0009] Preferably, in S2, the hole guide angle structure is a tapered hole structure, and the large end diameter of the tapered hole is larger than the final formed hole diameter of the pre-drawn hole in S3.

[0010] By adopting this technical solution, the larger diameter of the tapered lead-in angle is larger than the final diameter of the pre-drawn hole. This effectively guides material flow inward, reducing resistance during subsequent drawing and lowering the risk of cracking. The tapered structure also helps disperse stress, resulting in more uniform pre-drawn hole formation, improved aperture accuracy and surface quality, and ultimately, enhanced overall valve seat performance.

[0011] Preferably, in S2, during the chamfer formation process, a guiding slope is formed between the first lower punch rod and the mold, and the inclination angle of the guiding slope is consistent with the inclination angle of the bottom chamfer.

[0012] By adopting the above technical solution, the angle of the lower punch rod and the guide bevel of the mold are consistent, ensuring accurate and stable chamfering. This design reduces the offset of the punch rod, avoids excessive deformation or uneven extrusion of the material, and improves the smoothness and dimensional accuracy of the chamfered surface. Precise guidance reduces mold wear, extends its service life, and ultimately ensures product quality consistency.

[0013] Preferably, in S3, in the pre-hole back-extrusion step, an annular limiting groove is formed between the second upper punch rod and the main mold, and the annular limiting groove is used to limit the lateral displacement of the material flowing upward.

[0014] By adopting the above technical solution, the annular limit groove restricts the upward lateral flow of material, avoiding excessive accumulation of material and forming defects; it guides the material to fill in the predetermined direction, ensuring the dimensional accuracy and shape stability of the pre-drawn hole; this design can also reduce the force on the punch, extend the life of the mold, and improve the reliability of the back-extrusion process, thereby improving product quality and production efficiency.

[0015] Preferably, in S4, in the flange preforming step, the head of the third upper punch rod is provided with a concave cavity matching the final contour of the flange, and the depth of the concave cavity differs from the height of the flange prototype by less than 0.5 mm.

[0016] By adopting the above technical solution, the recessed cavity that matches the flange contour accurately controls the flange molding, ensuring that the size and shape meet the design requirements; the difference between the cavity depth and the flange prototype height is less than 0.5mm, reducing excessive material flow and avoiding wrinkles and deformation. This design reduces the need for subsequent finishing, improves the surface quality and dimensional accuracy of the flange, and thus enhances the overall performance of the part.

[0017] Preferably, in S4, in the inner hole pre-stretching step, the outer wall of the second lower punch rod is provided with a spiral guide groove, and the spiral guide groove is used to guide the inner hole material to flow uniformly along the axial direction.

[0018] By adopting the above technical solution, the spiral guide groove guides the inner hole material to flow evenly along the axial direction, avoiding concentrated accumulation or uneven stretching of the material, and effectively reducing the risk of cracking during inner hole forming; uniform flow can also improve the dimensional accuracy and surface finish of the inner hole, improve the microstructure of the material, and enhance the overall strength and durability; this design ultimately guarantees the quality and stability of the inner hole.

[0019] Preferably, in S5, in the flange final forming step, the relative motion trajectory between the fourth upper punch rod and the third lower punch rod is a spiral propulsion type, and the pitch of the spiral propulsion matches the curvature radius of the flange profile.

[0020] By adopting the above technical solution, the spiral propulsion motion is combined with the curvature radius to gradually form the flange material, avoiding cracking or wrinkling caused by severe deformation at one time; this precise control can improve the accuracy and surface quality of the flange contour, reduce stress concentration, and improve the overall strength and stability of the part; spiral propulsion also reduces the impact load of the mold, extending its service life, thereby ensuring production efficiency.

[0021] Preferably, in S6, in the step of punching out the waste, the cutting edge of the fifth upper punch rod is provided with a rounded corner structure, and the radius of the rounded corner matches the thickness of the waste fracture zone.

[0022] By adopting the above technical solution, the rounded corner structure of the cutting edge of the upper punch can effectively control the fracture position of the scrap, so that it can be accurately separated along the predetermined fracture zone, avoiding burrs and irregular tearing; the radius that matches the thickness of the scrap fracture zone reduces the punching force, reduces the risk of mold wear and part deformation, improves the punching quality and efficiency, and ensures the smooth progress of subsequent processes.

[0023] Preferably, in S2 and S3, the bevel chamfer forming step and the bottom chamfer optimization step are implemented by the same mold module, and the mold module includes a replaceable bevel bushing and a bottom forming block.

[0024] By adopting the above technical solution, the optimization of bevel chamfers and bottom chamfers can be achieved through the same mold module, which reduces the number of molds and mold change time, and reduces production costs; the replaceable bevel bushings and bottom forming blocks improve the flexibility and adaptability of the mold, and can be quickly adjusted to meet the chamfering requirements of different parts, thereby enhancing the flexibility and efficiency of the production line.

[0025] In summary, this application has the following beneficial effects: 1. The valve seat cold extrusion forming method is a precision manufacturing process based on cold extrusion forming. Through progressive plastic deformation in multiple steps, the entire process does not require heating, the material utilization rate is high, and the staged forming strategy effectively reduces the forming force. Combined with the pre-tensioned hole back extrusion and bottom chamfer, it can effectively reduce the possibility of folding layers at the root of the valve seat hole, extend the mold life, and ultimately obtain valve seat parts with complex geometric shapes and fine dimensional requirements. Its core idea is to utilize the good plasticity and strength of metal materials in the cold state and realize the precise flow and forming of materials through the constraint effect of the mold. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart in this embodiment; Figure 2 This is a schematic diagram of the structure of the embodiment in the state of end face finishing and pre-forming chamfering processing; Figure 3 This is a schematic diagram of the structure of the pre-drawn hole in the reverse extrusion and bottom chamfering processing state in this embodiment; Figure 4 This is a schematic diagram of the structure of the flange pre-formed and inner hole pre-stretched processing state in this embodiment; Figure 5 This is a structural diagram of the embodiment of the present invention in the final forming state of the flange and the inner hole drawing process; Figure 6 This is a schematic structural diagram of the waste material punched with small holes in the present embodiment; Explanation of the accompanying drawings: 1. main mold; 2. first upper punch rod; 3. first lower punch rod; 4. second upper punch rod; 5. third upper punch rod; 6. second lower punch rod; 7. fifth upper punch rod; 8. fourth upper punch rod; 9. third lower punch rod. DETAILED DESCRIPTION

[0027] The present application is described in further detail below in conjunction with the accompanying drawings. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content. Example

[0028] The present invention discloses a valve seat cold extrusion forming method, which is used for forming inside a processing mold, wherein the processing mold includes a mold, an upper punch assembly, and a lower punch assembly, wherein the mold includes a main mold 1, and a cavity for accommodating an end face material is provided inside the main mold 1, and the lower punch assembly is located below the end face material in the cavity. Specifically, the upper punch assembly includes a first upper punch rod 2, a second upper punch rod 4, a third upper punch rod 5, a fourth upper punch rod 8 and a fifth upper punch rod 7; the lower punch assembly includes a first lower punch rod 3, a second lower punch rod 6 and a third lower punch rod 9.

[0029] like Figure 1 As shown, the processing steps of the valve seat cold extrusion molding method include like Figure 2 As shown, S1: end surface finishing and pre-forming chamfering; T1: end surface leveling; By eliminating the end face collapse and unevenness caused by shearing, the positioning accuracy of subsequent processes and the reliable contact of the mold are ensured.

[0030] By using stamping or extrusion, the end surface material undergoes plastic deformation, achieving a flat state. This provides a precise machining reference surface for subsequent processes, improving machining accuracy, reducing mold wear, and reducing scrap rates.

[0031] T2: preformed chamfer; A first upper punch rod 2 is used; a certain chamfer shape is pre-formed at the end of the part, laying the foundation for subsequent fine chamfering and reducing the forming resistance of subsequent processes. The pre-formed chamfer is a conical structure with the top tilted inward, and the taper of the conical structure and the angle between the end face of the blank are in the range of 15°-45°.

[0032] The optimized metal flow path of the T2 pre-formed chamfer helps to better play the role of T1 end face leveling in providing a precise reference in subsequent processes. The two together improve processing accuracy and reduce mold wear.

[0033] Specifically, the first upper punch 2 applies pressure to the material, causing it to flow plastically and forming a preliminary chamfered profile at the top. This effectively disperses stress concentration, extends the life of the first upper punch 2 and the main mold 1, and reduces the risk of cracking. Preforming can optimize the metal flow path.

[0034] End face finishing and pre-forming chamfering in S1, end face leveling eliminates unevenness caused by blanking, provides a precise reference surface, and ensures positioning accuracy of subsequent processes and reliable contact with the mold; pre-forming chamfering disperses stress, optimizes metal flow, and reduces resistance for subsequent fine chamfering and other forming processes, which is the basic preparation for the entire processing flow.

[0035] S2: Pre-forming and chamfering of the head hole angle; T1: pre-forming of the head hole angle; The first upper punch 2 is used to pre-form a small hole-leading angle on the part head, providing an accurate positioning reference for the subsequent hole-drawing process. The hole-leading angle structure is a tapered hole structure, and the large end diameter of the tapered hole is larger than the final formed hole diameter of the pre-drawing hole described below.

[0036] Specifically, the first upper punch rod 2 causes the material to undergo plastic deformation in the center of the head, forming a tapered hole-drawing structure, which is used to ensure the center position accuracy of the subsequent hole-drawing process and avoid hole deflection or displacement.

[0037] T2: chamfer forming; The first lower punch rod 3 in the main mold 1 is used to form an oblique chamfer at the bottom of the part, which concentrates pressure for the subsequent hole drawing process and offsets the end face overflow that may be generated in the subsequent flange pressing process.

[0038] Specifically, the special shape formed between the main die 1 and the first lower punch 3 forces the material to flow along the inclined surface during extrusion, forming a chamfer. This serves to concentrate pressure, assist in hole drawing, control metal flow, and ensure flange forming quality. The chamfer controls the direction of metal flow.

[0039] During the chamfer formation process, a guiding slope is formed between the first lower punch rod 3 and the die, and the inclination angle of the guiding slope is consistent with the inclination angle of the bottom chamfer.

[0040] In general, the T1 head hole angle pre-forming provides a positioning reference for the subsequent hole drawing, and the T2 chamfer forming concentrates the pressure of the hole drawing and controls the metal flow. The two work together to ensure the center position accuracy of the hole drawing process and the rationality of the metal flow, and together create good conditions for the hole drawing process.

[0041] S2 performs pre-forming and chamfering of the head hole angle. The head hole angle provides a positioning reference for the hole drawing. The chamfer concentrates the pressure of the hole drawing, controls the metal flow, and offsets the overflow of the subsequent flange pressing process. Cooperating with S1, it further creates conditions for the subsequent hole drawing and flange forming.

[0042] like Figure 3 As shown, S3: pre-drawn hole back extrusion and bottom chamfering; T1: pre-tensioned hole reverse extrusion; A second upper punch rod 4 is used to pre-pull a small hole in the center of the part and simultaneously perform reverse extrusion to allow the material to flow upward, providing sufficient material for subsequent flange forming.

[0043] Specifically, the second upper punch 4 applies pressure to the material, causing it to flow plastically, and the center portion is squeezed upward to form a pre-drawn hole, thereby controlling the direction of material flow, providing sufficient material for subsequent flange forming, and reducing the risk of overflow.

[0044] T2: bottom chamfer; Through the main die 1 and in conjunction with the pre-drawn hole back extrusion, an annular limiting groove is formed between the second upper punch rod 4 and the main die 1. The annular limiting groove is used to limit the lateral displacement of the upward flow of the material. The chamfer shape of the bottom of the part is further optimized to create conditions for subsequent flange forming.

[0045] The chamfer forming step and the bottom chamfer optimizing step are implemented by the same mold module, and the mold module includes a replaceable bevel bushing and a bottom forming block.

[0046] In general, the shape of main mold 1 guides material flow along the chamfer direction, ensuring smooth material flow during flange forming and preventing overflow. The T1 pre-drawn hole back-extrusion provides sufficient material for flange forming, while the T2 bottom chamfer optimizes the part's bottom shape, ensuring smooth material flow along the chamfer direction during flange forming. These two elements work together to provide both material and shape assurance for flange formation.

[0047] S3's pre-tensioned hole back-extrusion and bottom chamfering provide sufficient material for flange forming, and the bottom chamfering optimizes the shape to ensure smooth material flow during flange forming. Together with S1 and S2, it paves the way for flange forming in terms of material preparation and shape optimization.

[0048] like Figure 4As shown, S4: flange preforming and inner hole pre-stretching; T1: flange pre-forming; The third upper punch 5 is used to pre-form the prototype of the flange at the upper end of the part and guide the end face chamfering to prepare for the subsequent final forming of the flange.

[0049] Specifically, the third upper punch 5 causes the material to undergo plastic deformation at the upper end of the part to form a preliminary flange shape, thereby reducing deformation in subsequent processes, lowering forming force, and increasing mold life.

[0050] The head of the third upper punch rod 5 is provided with a concave cavity matching the final contour of the flange, and the difference between the depth of the concave cavity and the height of the flange prototype is less than 0.5 mm.

[0051] T2: inner hole pre-stretching; The second lower punch rod 6 is used to pre-stretch the inner hole of the part to provide guidance for the subsequent hole-drawing process and optimize the material structure.

[0052] Specifically, in the inner hole pre-stretching step, the outer wall of the second lower punch rod 6 is provided with a spiral guide groove, and the spiral guide groove is used to guide the inner hole material to flow uniformly along the axial direction. Through the action of the second lower punch rod 6, the inner hole material undergoes plastic deformation and the aperture is slightly increased. It is used to reduce the difficulty of subsequent hole drawing and improve the dimensional accuracy and surface quality of the hole. T1 flange pre-forming forms the flange prototype to reduce the subsequent deformation amount, and T2 inner hole pre-stretching optimizes the material structure and reduces the difficulty of subsequent hole drawing. The two work together to prepare for the final forming from both the flange and the inner hole, thereby improving the overall quality of the part.

[0053] S4's flange pre-forming and inner hole pre-stretching: flange pre-forming forms a prototype to reduce deformation in subsequent processes; inner hole pre-stretching optimizes the material structure and reduces the difficulty of subsequent hole drawing. It works in conjunction with the previous steps to further improve the shape and structure of the part and prepare for final forming.

[0054] like Figure 5 As shown, S5: final forming of flange and inner hole drawing; T1: final flange formation; Through the coordinated action of the fourth upper punch 8 and the third lower punch 9, the material is squeezed and plastically flowed to form a precise flange profile, so that the flange reaches the final shape and size requirements, thereby obtaining the flange size, angle and surface quality that meet the requirements of the drawing.

[0055] T2: further drilling of the inner hole; The cooperation of the fourth upper punch 8 and the third lower punch 9 further stretches the inner hole, causing plastic deformation of the inner hole material, increasing the hole diameter and improving the surface finish. This ensures that the final size and precision requirements are met and ensures the punching position accuracy in subsequent processes. This ensures the inner hole size accuracy and surface quality, providing a reliable benchmark for subsequent processing.

[0056] In general, the final forming of the T1 flange and the further drawing of the T2 inner hole are achieved through the coordinated cooperation of the fourth upper punch rod 8 and the third lower punch rod 9, while achieving the final size and precision requirements of the flange and the inner hole, ensuring that the parts meet the design standards.

[0057] like Figure 6 As shown, S6: Punching small hole waste The cutting edge of the fifth upper punch 7 is provided with a rounded structure, the radius of which matches the thickness of the waste material fracture zone. Through the blanking action of the fifth upper punch 7, the waste material at the fracture zone is flushed away and separated from the part, ensuring that the hole is free of burrs, thereby ensuring the quality of the hole and avoiding affecting subsequent assembly and use.

[0058] In general, this valve seat cold extrusion method is a typical cold extrusion process. Through precise control of multiple process steps, it enables the manufacture of parts with complex geometries and precise dimensional requirements. Its advantages include: 1. Cold extrusion achieves high dimensional accuracy and surface finish. 2. It is suitable for large-scale production and has high production efficiency. 3. It achieves high material utilization and minimizes waste. 4. Cold extrusion can increase the strength and hardness of the material.

[0059] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A valve seat cold extrusion molding method, characterized in that: The molding steps include: S1: end surface finishing and pre-forming chamfering, the end surface of the blank is leveled and placed inside the main mold (1), and pressure is applied to the end surface by a first upper punch rod (2) to form a pre-forming chamfer; S2: Preforming of the hole-leading angle and the chamfering of the head, forming the hole-leading angle structure in the central area of ​​the head of the blank by the first upper punch rod (2), and forming the chamfering at the bottom of the blank by the first lower punch rod (3) in cooperation with the die; S3: pre-pull hole reverse extrusion and bottom chamfering, the second upper punch rod (4) is used to extrude the hole guide angle structure to form a pre-pull hole, and the die is used to guide the material to flow along the oblique chamfer direction to optimize the bottom chamfer shape; S4: flange pre-forming and inner hole pre-stretching, the upper end of the blank is squeezed by the third upper punch rod (5) to form a flange prototype, and the pre-stretched hole is expanded by the second lower punch rod (6) to form a pre-stretched inner hole; S5: final forming of the flange and drawing of the inner hole, the flange prototype is formed into the final flange profile by the cooperative extrusion of the fourth upper punch rod (8) and the third lower punch rod (9), and at the same time, the pre-stretched inner hole is further stretched by the cooperation of the fourth upper punch rod (8) and the third lower punch rod (9) to form the final inner hole; S6: Punching out waste material, punching out waste material at the connection between the flange and the pre-drawn hole by the fifth upper punch rod (7).

2. The valve seat cold extrusion molding method according to claim 1, characterized in that: In S1, the preformed chamfer is a conical structure with the top inclined inward, and the taper of the conical structure and the angle between the end face of the blank are in the range of 15°-45°.

3. The valve seat cold extrusion forming method according to claim 1, characterized in that: In S2, the hole guide angle structure is a tapered hole structure, and the large end diameter of the tapered hole is larger than the final formed hole diameter of the pre-drawn hole in S3.

4. The valve seat cold extrusion molding method according to claim 1, characterized in that: In S2, during the chamfer forming process, a guiding slope is formed between the first lower punch rod (3) and the die, and the inclination angle of the guiding slope is consistent with the inclination angle of the bottom chamfer.

5. The valve seat cold extrusion molding method according to claim 1, characterized in that: In S3, in the pre-pull hole reverse extrusion step, an annular limiting groove is formed between the second upper punch rod (4) and the main die (1), and the annular limiting groove is used to limit the lateral displacement of the material flowing upward.

6. The valve seat cold extrusion molding method according to claim 1, characterized in that: In S4, in the flange preforming step, the head of the third upper punch rod (5) is provided with a recessed cavity matching the final contour of the flange, and the difference between the depth of the recessed cavity and the height of the flange prototype is less than 0.5 mm.

7. The valve seat cold extrusion molding method according to claim 1, characterized in that: In S4, in the inner hole pre-stretching step, the outer wall of the second lower punch rod (6) is provided with a spiral guide groove, and the spiral guide groove is used to guide the inner hole material to flow uniformly along the axial direction.

8. The valve seat cold extrusion molding method according to claim 1, characterized in that: In S5, in the final forming step of the flange, the relative motion trajectory between the fourth upper punch rod (8) and the third lower punch rod (9) is a spiral propulsion type, and the pitch of the spiral propulsion matches the curvature radius of the flange profile.

9. The valve seat cold extrusion molding method according to claim 1, characterized in that: In S6, in the step of punching out the waste, the cutting edge of the fifth upper punch rod (7) is provided with a rounded corner structure, and the rounded corner radius matches the thickness of the waste fracture zone.

10. The valve seat cold extrusion molding method according to claim 1, characterized in that: In S2 and S3, the bevel chamfer forming step and the bottom chamfer optimizing step are implemented by the same mold module, and the mold module includes a replaceable bevel bushing and a bottom forming block.

Images