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CN-122007196-A - Single-station continuous forming method for shell extrusion and necking

CN122007196ACN 122007196 ACN122007196 ACN 122007196ACN-122007196-A

Abstract

The invention provides a single-station continuous forming method for shell extrusion and necking, which comprises an extrusion forming step, wherein a blank is placed in a female die cavity of a lower female die, an upper die assembly is controlled to descend after an extrusion male die is assembled on an upper die plate so as to extrude the blank into a blind hole shell with preset wall thickness and bottom thickness, and a shell necking step, an upper die assembly is controlled to ascend so as to enable the extrusion male die to deviate from a cavity opening of the female die cavity, the extrusion male die is removed from the upper die plate, a necking die is assembled on the upper die plate, and the upper die assembly is controlled to descend again until a conical opening is buckled with the top end of the blind hole shell to form a necking shell. The invention can realize high-quality forming of the necking shell member by replacing the male die in the upper die assembly and sharing the same lower die assembly, effectively reduces the time consumption of die replacement, reduces the heat dissipation of blanks, ensures the efficient necking of the shell, improves the forming quality of the necking shell, and effectively reduces the manufacturing cost of the die and the forming cost of products.

Inventors

  • ZHAO XI
  • WANG DENGKUI
  • GAO YIHAN
  • Qiao Siao
  • YAN GUOHUA

Assignees

  • 中北大学

Dates

Publication Date
20260512
Application Date
20260330

Claims (10)

  1. 1. The utility model provides a shell extrusion and throat single-station continuous forming method which is characterized in that adopts the shell forming die to carry out, the shell forming die includes upper die subassembly and lower die subassembly, lower die subassembly includes lower bolster (11) and locates lower die (12) on it, lower die (12) have die cavity (121), upper die subassembly includes cope match-plate pattern (21) and optionally assembles extrusion punch and throat mould (24) on cope match-plate pattern (21) orientation lower die (12) one side face, be formed with on the downside terminal surface of throat mould (24) big-end-up's conical opening (241), the shaping method includes the following steps: An extrusion forming step of placing a blank (100) in a die cavity (121) of the lower die (12), and controlling the upper die assembly to descend after the extrusion male die is assembled on the upper die plate (21) so as to extrude the blank (100) to form a blind hole shell with preset wall thickness and bottom thickness by the blank (100); And (3) a shell necking step, namely controlling the upper die assembly to ascend so as to enable the extrusion male die to deviate from a cavity opening of the female die cavity (121), removing the extrusion male die from the upper die plate (21), assembling a necking die (24) on the upper die plate (21), and controlling the upper die assembly to descend again until the conical opening (241) is buckled with the top end of the blind hole shell to form a necking shell.
  2. 2. The forming method according to claim 1, characterized by further comprising the step of, after the extrusion step, before the shell necking step: And a step of locally heating the shell, namely heating the top end area of the blind hole shell, and putting the blind hole shell with the heated top end area into the female die cavity (121) again.
  3. 3. The forming method according to claim 1 or 2, wherein the extrusion punch comprises a counter extrusion punch (22) and a cone drawing punch (23), the lower die assembly further comprises a spacer block (122) positionable at a bottom of the die cavity (121), the extrusion step specifically comprising: Placing the cushion block (122) at the cavity bottom of the female die cavity (121), then placing the blank (100) in the female die cavity (121), and controlling an upper die assembly assembled with the pressing and back extrusion male die (22) to descend so that the blank (100) is back extruded to form an intermediate blank with a central blind hole; Taking the intermediate blank and the cushion block (122) out of the die cavity (121), and replacing and assembling the cone extrusion deep drawing punch (23) after the compression and reverse extrusion punch (22) is discharged from the upper die plate (21); And controlling the upper die assembly to descend again to form deep drawing extrusion on the intermediate blank body so as to form the blind hole shell.
  4. 4. A forming method according to claim 3, wherein the lower die (12) comprises an inner die body (1201) and an outer die body (1202) fitted over a radially outer side wall surface of the inner die body (1201), the die cavity (121) is formed on the inner die body (1201), and/or a cavity bottom of the die cavity (121) is conical with a large upper side and a small lower side, and a longitudinal section of the cushion block (122) is conical in shape matching the cavity bottom.
  5. 5. The molding method according to claim 4, wherein a cooling runner (1203) is formed in the outer mold body (1202), the cooling runner (1203) is formed on a mating annular surface of the inner mold body (1201) and the outer mold body (1202), the cooling runner (1203) has an inflow channel (1204) and an outflow channel (1205), a cooling fluid is introduced into the cooling runner (1203) and circulated in the extrusion molding step, and/or a lower shim plate (13) is provided between the outer mold body (1202) and the lower mold plate (11), a ram passing hole (131) communicating with a cavity bottom of the cavity (121) is formed in the lower shim plate (13), a ram (14) passes through the lower mold plate (11), the ram passing hole (131) in order, and the ram (14) has a stopper ring (141) protruding radially outward therefrom, the ram (14) has a ram position and a stopper position and can be driven to be lifted between the ram position and the ram position, and the ram (14) is located at the stopper position when the ram (14) is located at the stopper position of the inner mold body (1201), the limiting ring (141) is abutted against the top side of the lower die plate (11) and the top end of the ejector rod (14) is inserted into the cavity bottom of the female die cavity (121), and when the middle blank body, the blind hole shell and the necking shell are discharged from the female die cavity (121), the ejector rod (14) is controlled to be positioned at the ejection position, and when force is applied to the blank (100), the middle blank body, the blind hole shell and the necking shell, the ejector rod (14) is controlled to be positioned at the blocking position.
  6. 6. The forming method according to claim 5, characterized in that an upper female die plate (15) is detachably assembled on the top side end surface of the outer die body (1202), a first central through hole corresponding to the top side cavity opening of the female die cavity (121) is formed in the upper female die plate (15), the acting ends of the pressing counter-extrusion male die (22) and the extrusion cone drawing male die (23) can be inserted into the female die cavity (121) through the first central through hole, the lower die assembly further comprises a die opening guide sleeve (16) and a stripper plate (17), a second central through hole is formed in the die opening guide sleeve (16), the upper orifice diameter of the second central through hole is equal to the main body outer diameter of the pressing counter-extrusion male die (22), when the pressing counter-extrusion male die (22) is assembled on the upper die plate (21), the die opening guide sleeve (16) is assembled on the upper female die plate (15) and is arranged coaxially with the first central through hole, and when the extrusion cone (23) is assembled on the upper male die (23) and the extrusion cone (23) can be drawn off the upper die plate (23) from the upper die plate (23) in a deep drawing process.
  7. 7. The forming method according to claim 6, characterized in that the upper die assembly further comprises a support mandrel (25) selectively assembled to the side of the upper die plate (21) facing the lower die (12), the support mandrel (25) passing through the conical opening (241), the support mandrel (25) being adapted to form a radial support for the top end of the blind hole blank during the shell necking step.
  8. 8. The forming method according to claim 7, wherein the upper die assembly further comprises a punch holder (27) and a punch retainer (28) which are stacked in sequence along a direction away from the upper die plate (21) and are positioned on one side of the upper die plate (21) close to the lower die plate (11), wherein the punch retainer (28) is detachably assembled on the bottom side end surface of the punch holder (27), a punch collar (29) with a conical positioning hole is formed in a central area of the punch retainer (20), an inverted conical ring matched with the conical positioning hole is formed at the top end of the main body of the pressing and reversely extruding punch (22), the extruding and drawing punch (23) and the supporting mandrel (25), the diameter of the conical positioning hole is gradually reduced from top to bottom, a first insertion hole is formed on the punch holder (27), a second insertion hole is formed on the punch retainer (28), and the diameter of the first insertion hole is larger than that of the second insertion hole.
  9. 9. The forming method according to claim 8, wherein the punch collar (29) and the punch fixing ring (28) are separately arranged, and/or an upper base plate (26) is further arranged between the upper die plate (21) and the punch holder (27), and the main body top end surfaces of the extrusion counter punch (22), the extrusion cone drawing punch (23) and the supporting core die (25) can be abutted against the bottom side end surfaces of the upper base plate (26).
  10. 10. The forming method according to claim 7, characterized in that, before the extrusion forming step, the blank (100) is heated to a forming temperature and preheated to a heat-preserving lower die (12), a press-forming counter-extrusion die (22), a cone-extrusion drawing die (23) and a necking die (24), and/or that the parts of the lower die (12), the press-forming counter-extrusion die (22), the cone-extrusion drawing die (23), the necking die (24) and the ejector pin (14) in contact with the blank (100) are uniformly sprayed with a lubricant.

Description

Single-station continuous forming method for shell extrusion and necking Technical Field The invention belongs to the technical field of metal forming, and particularly relates to a single-station continuous forming method for shell extrusion and necking. Background The thick-wall necking shell type member (particularly the thick-wall necking shell type member with large height-to-diameter ratio) has excellent complex load bearing capacity, light weight level and carrying benefit due to the special structure, is widely applied to the fields of aerospace equipment, weaponry, underwater equipment, pressure equipment key bearing parts and the like which have severe requirements on the service capacity of the member under extreme working conditions, and the like, and is usually made of metal materials such as high-strength alloy steel, ultrahigh-strength aluminum alloy and the like for ensuring high strength. The structural characteristics, performance requirements and material selection characteristics of the components make the balance among the three aspects of preparation efficiency, component performance and preparation cost challenging. The large aspect ratio generally refers to H/D≥3 (H is the height of the formed housing member, D is the maximum outer diameter of the body of the formed housing member), and the thick wall refers to t/D >0.1 (t is the wall thickness of the body of the formed housing member). The preparation method of the thick-wall necking shell member with the large height-diameter ratio mainly comprises machining, spinning-necking forming and extrusion-necking forming. The spinning forming is also a preparation method of the parts, which has the advantages of higher material utilization rate and convenient necking, but has the defects of long processing period, poor structural and performance uniformity of the components, obvious texture, anisotropic mechanical properties of the components and lower preparation efficiency, so the spinning technology is not suitable for low-cost manufacture of conical shells with small diameters and large height-diameter ratios. The extrusion-necking forming method is a forming method commonly used for thick-wall necking shell members with large height-to-diameter ratio. The method generally relates to back extrusion-necking forming and back extrusion-ironing-necking forming, and as shown in fig. 1, the back extrusion forming has the advantages that metal is subjected to a three-way compressive stress state in the extrusion process, plastic deformation can be fully carried out, and higher tissue performance improvement is obtained, but the back extrusion forming has the disadvantages that a metal flow path in the back extrusion process is long, a blank is in large-area contact with a die to generate high friction resistance and back stress, a male die with a large height-diameter ratio is easy to lose efficacy when repeatedly bearing a large forming load, the service life of the die is greatly reduced, and the occurrence of failure can be delayed only through a multi-pass heating and extrusion method which sacrifices the preparation efficiency, so that the energy consumption is increased, and the safety risk is still provided. As shown in fig. 2, the back extrusion-ironing has the advantages that the contact area of the blank and the female die is small, the integral forming load can be reduced, but the single deformation pass is limited by the ironing coefficient, the deformation requirement can be met only by multi-pass ironing, the processes of extrusion, ironing and the like are realized by multi-pass heating and replacing of multiple sets of dies in the forming process, and the thin-wall shell with small diameter is easy to be unstable. Thus, extrusion-necking forming methods are the low cost manufacturing option for such components. The continuous forming of the extrusion-necking forming process of the thick-wall necking shell type component with large height-diameter ratio generally relates to extrusion-spinning equipment, extrusion-necking special equipment linkage or multi-station extrusion equipment and dies, and has the advantages of automatic development and high production speed, but has the defects of high equipment and die development cost and complex process development. In the related art, the single-station extrusion-necking forming method of the thick-wall necking shell type component with large height-diameter ratio generally needs to realize the necking process by replacing the whole set of die after the extrusion forming process is finished. Disclosure of Invention Therefore, the invention provides a single-station continuous forming method for shell extrusion and necking, which can overcome the defects that in the prior art, the single-station extrusion-necking forming method needs to carry out necking by replacing the whole die after the extrusion forming process is finished, the die is replaced for a long time, and the heat dissi