[0014] The embodiments of the present invention are given in conjunction with the drawings:
[0015] Such as figure 1 As shown, the concave mold 8 is a cone with a through hole in the upper narrow and lower width. The inner diameter of the through hole matches the diameter of the solid cylindrical blank 17, which is embedded in the inner cone cavity of the pretension ring 3 and fixed The first-order punch 7 is a solid shaft with a stepped round platform at the upper end, and the outer diameter is matched with the inner diameter of the first-order extruded tube blank 19 to be formed; the first-order punch 7 is embedded in the convex through its upper end stepped round platform The mold fixing plate 2 is fixed in the step round hole and the convex mold fixing plate 2 is connected to the hydraulic press lifting beam through the backing plate 1, the upper template 6; the lower part is a concave mold structure: the mold base of the concave mold 8 includes: The pre-tightening ring 3, the first-order ejector 4, the first-order concave die backing plate 5, the lower template 9 and the first-order ejector 10. The first die backing plate 5 located at the upper end of the lower mold plate 9 and the pre-tightening ring 3 on the upper end of the backing plate are bolted to the lower mold plate 9, and the female mold 8 is located at the upper end of the first die backing plate 5, and its cone is embedded in the pre-tightening ring 3 is fixed in the inner cone cavity, the first ejector 4 is located at the lower part of the inner hole of the die 8, the upper end of the first die backing plate 5, and the first ejector 10 is located at the lower end of the first ejector 4 and passes through the lower template 9 Middle through hole.
[0016] Such as figure 2 As shown, the second-order movable punch 12 is a cylinder with a chamfered upper end, which is matched with the lower through hole of the second-order fixed punch 16; the second-order movable punch 12 is placed in the first-order extrusion tube 19 during operation, Its lower end is embedded in the circular hole on the upper part of the second sequence ejector 14; the second sequence fixed punch 16 is a hollow shaft structure, and its upper end has a round table and the lower end is a tapered surface structure. The center of the second sequence fixed punch 16 is an upper and lower diameter. Different stepped through holes, and the lower through holes are matched with the second-sequence movable punch 12, so that it can move downward along the second-sequence movable punch 12 to squeeze the first-sequence extrusion tube blank, and the second-sequence fixed convex The mold 16 is embedded in the step round hole of the convex mold fixing plate 2 through the upper round table, and the convex mold fixing plate 2 is connected to the lifting beam of the hydraulic press through the backing plate 1 and the upper template 6. The die seat structure of the concave mold 8 includes the pre-tightening ring 3, the second sequence ejector 14 and the second sequence concave mold backing plate 13, the lower template 9 and the second sequence ejector 15 and the top pipe 11; the second sequence located at the upper end of the lower template 9 The die backing plate 13 and the pre-tightening ring 3 on the upper end of the backing plate are bolted to the lower template 9. The die 8 is located at the upper end of the second-sequence die backing plate 13, and its cone is embedded in the inner cone cavity of the pre-tightening ring 3 to be fixed , The second sequence ejector 14 is located at the lower part of the inner hole of the female mold 8 and the upper end of the second sequence female mold backing plate 13, the lower end of the second sequence movable punch 12 is embedded in the upper circular hole of the second sequence ejector 14, and the second sequence ejector 15 Located at the lower end of the second-sequence movable punch 12 and passing through the middle through hole of the top pipe 11, the top pipe 11 is located at the lower end of the second-sequence ejector 14 and passing through the middle through hole of the lower template 9.
[0017] A precision extrusion forming method for thin-walled long tubular parts, the method comprising the following steps;
[0018] First, the solid cylindrical blank 17 heated to 700-800°C and kept for 30 minutes is placed in the lower part of the cavity of the concave film 8 at a temperature of 400-500°C, and the upper end of the first-order ejector 4, and then the upper template 6 lifts the beam with the hydraulic press When descending, it drives the backing plate 1, the convex mold fixing plate 2 and the first convex mold 7 to move downwards. The first convex mold 7 gradually enters the cavity of the concave film 8 and then squeezes the blank. The blank metal follows the space between the convex and concave films. The cavity flows upward, and the lower end of the first-order convex mold 7 moves to a certain distance from the upper end of the first-order ejector 4 and stops moving. The distance is determined by the extrusion process. After the first-order reverse extrusion is completed, the upper template 6 rises with the lifting beam of the hydraulic press. Drive the backing plate 1, the convex mold fixing plate 2 and the first convex mold 7 to rise. After the first convex mold 7 leaves the cavity of the concave film 8, the first ejector rod 10 drives the first ejector 4 to eject the squeezed With a sequential extrusion of the skin 18.
[0019] Reheat the first-order extruded piece 19 from which the continuous skin has been removed to 700-800°C and keep it for 30 minutes, and put it into the lower part of the cavity of the concave film 8 and the upper end of the second-order ejector 14 at a temperature of 400-500°C. The movable punch 12 is placed in the lower part of the cavity of the female mold 8 and the upper end of the second-order ejector 14, and then the upper template 6 is lowered with the lifting beam of the hydraulic press, driving the backing plate 1, the convex mold fixing plate 2 and the second-order fixed convex mold 16 directions Move down, the second-sequence fixed convex mold 16 squeezes the first-sequence extrusion tube 19, and the metal flows upward along the outer wall of the second-sequence movable punch 12, so that the wall of the tube becomes thinner and the length gradually increases; When the lower end of the die 16 is at a certain distance from the upper end of the second-order ejector 14, the distance is determined by the wall thickness of the lower end of the thin-walled long tube-shaped part blank to complete the second-order reverse extrusion; the second-order fixed convex die 16 is driven by the hydraulic press After rising downwards and separating from the second-sequence extruded tube 20, the second-sequence ejector rod 15 first pushes the second-sequence movable punch 12 upwards from the bottom hole of the tube blank into the inner hole of the tube blank, and the ejector continues to move upwards for the second sequence At the same time as the convex mold 12, the second-sequence extruded tube blank 20 is ejected upward through the pipe jack 11 and the second-sequence ejector 14, so that the second-sequence movable convex mold 12 and the second-sequence extruded tube blank 20 are separated from the female mold 8.
[0020] Since this mold structure reduces the length of a movable punch compared with the traditional stepped integral punch, the distance between the upper and lower molds after the mold is opened can meet the requirements of demolding the workpiece on the small stroke hydraulic press.
