A forming method of a titanium alloy extruded piece with two ends and three-pronged branches

Abstract

The application relates to the field of plastic processing and forming technology of metal materials, and particularly relates to a forming method of a two-end three-prong branch long-rod type titanium alloy extrusion piece. The method comprises the following steps: rod material blanking; drawing a middle part of the rod material to form an initial-state rod part, and keeping two end heads unchanged; extrusion forging is carried out on the two end heads by using a tool, so that the cross section of the end heads becomes an irregular axisymmetric hexagon, the irregular axisymmetric hexagon is an equilateral triangle with top and bottom angles removed; the central axis of the new end head is coaxial with the central axis of the initial-state rod part; the initial-state rod part is drawn to obtain a rough blank, the diameter of the rod part of the rough blank is the same as the diameter of the rod part of the forged piece; die forging is carried out on the rough blank, metal of the end head of the rough blank flows into a special-shaped cavity for forming the end head of the forged piece, and metal of the rod part of the rough blank flows into a cavity for forming the rod part of the forged piece.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plastic working and forming of metal materials, and particularly relates to a forming method of a two-end three-pronged branch long rod type titanium alloy extrusion piece. BACKGROUND

[0002] The highest speed of a modern spacecraft in flight has reached more than 2.7 times the speed of sound. Such fast supersonic flight can cause a spacecraft to generate a large amount of heat by friction with air. At this time, a high-temperature-resistant material must be used. The "space metal" titanium is the first to be used, which is light in weight, high in strength, good in corrosion resistance and high in temperature resistance, and is particularly suitable for manufacturing various spacecraft. Titanium alloy is mainly used in the manufacture of aircraft and engines in aviation, and can meet the use performance. When this extrusion piece is formed by using a free forging method, the problem of different shafts of the two end heads and the rod part is easily caused, the forming shape of the two end heads of the rod part is irregular, it is difficult to meet the forging piece processing requirements, and the operation is difficult, and the material utilization rate is low. SUMMARY

[0003] The present application aims at the defects and deficiencies of the prior art, and provides a forming method of a two-end three-pronged branch long rod type titanium alloy extrusion piece. The preforming structure of the extrusion piece is reasonably designed, the yield of titanium alloy forgings and the utilization rate of materials are improved, the forming process is simple, the production efficiency is greatly improved, and the performance of the extrusion piece is improved.

[0004] Technical scheme:

[0005] A forming method of a two-end three-pronged branch long rod type titanium alloy extrusion piece, comprising:

[0006] rod blanking;

[0007] the middle part of the elongated rod is formed into an initial state rod part, and the two end heads remain unchanged;

[0008] the two end heads are extrusion forged by using a preforming piece tooling, so that the cross section of the end head becomes an irregular axisymmetric hexagon, and the irregular axisymmetric hexagon is an equilateral triangle with top and bottom corners removed; the central axis of the new end head is coaxial with the central axis of the initial state rod part;

[0009] the initial state rod part is elongated to obtain a rough blank, and the diameter of the rod part of the rough blank is the same as the diameter of the rod part of the forged piece;

[0010] the rough blank is die forged, the metal of the end head of the rough blank flows into a special-shaped cavity for forming the end head of the forged piece, and the metal of the rod part of the rough blank flows into a cavity for forming the rod part of the forged piece.

[0011] Before the middle part of the elongated rod is formed into a rough initial state rod part, the method further comprises:

[0012] The two ends of the bar are equipped with a feeding groove, so that when the preformed forging is formed, the irregular axisymmetric hexahedron at the two ends of the forging has sufficient forging volume.

[0013] The preform is extrusion forged at the two end heads by using a preform tooling, comprising:

[0014] The tooling for forming the new end head of the special-shaped preform is preheated to ≥350 DEG C and kept for ≥2h, and by using the axial symmetry of the hexagonal shape at the two ends of the preform rod, one corner end of one end of the rod is formed every 120 DEG during forging, so that three corner ends of one end head of the preform are obtained; the other new end head of the preform is formed by using the same method.

[0015] The preform tooling is a standard block with an inverted trapezoidal groove, and the end head is clamped in the inverted trapezoidal groove, and the included angle between the groove bottom and the groove wall is 120 DEG.

[0016] The process from the bar to the rough blank is completed in only one heating.

[0017] The die forging is completed in one heating.

[0018] The heating specification from the bar to the forging is that the heating is performed to 40 DEG C below the phase transition point, and the holding time is calculated according to the heating specification coefficient 0.8 min / mm.

[0019] The forming method of the two-end three-pronged branch long rod type titanium alloy extrusion part has the advantages that: the free forging preforming method is adopted, the irregular axisymmetric hexahedron tooling is used to form the preform structure of the extrusion part, the preform structure is ingenious, reliable, and easy to operate; the die forging final forming method is adopted, the overall and constraint of the die is used to form the profile of the extrusion part, the final forming structure is high in precision, strong in reliability, and good in formability; the forming process is divided into two stages of free forging preforming and die forging final forming, the direction of the forging is changed, the three-pronged branches at the two ends of the extrusion part are formed in stages, the three-pronged branches are formed completely and accurately, the streamline distribution is uniform, the formability is good, and there is no defect; the rod part of the forging is elongated twice, the operation is simple and easy to realize, the streamline is smooth, and there is no defect; the profile of the extrusion part is formed through the preforming and final forming stages, the metal flow can be well controlled, the arc edge of the irregular axisymmetric hexahedron with an arc, and the part connecting the irregular axisymmetric hexahedron with the rod part do not produce mechanical defects such as folding and cracking; the overall ejection device makes the material taking simple, and the overall operation is simplified. BRIEF DESCRIPTION OF DRAWINGS:

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0021] Figure 1 is a mold assembly diagram of the present application;

[0022] Figure 2 is Figure 1 is a sectional view in A-A direction in

[0023] Figure 3 is a tooling diagram of a preformed irregular axisymmetric hexagonal body;

[0024] Figure 4 is a schematic diagram of a preformed extrusion;

[0025] Figure 5 is a schematic diagram of a mold working state of a blank in final forming extrusion molding;

[0026] Figure 6 is a schematic diagram of a final forming extrusion;

[0027] wherein, 1, upper die plate; 2, inner hexagonal fastening bolt; 3, upper die; 4, lower die; 5, special-shaped ejector block; 6, lower die plate; 7, ejector rod; 8, tooling of a preformed irregular axisymmetric hexagonal body; 3-1, cavity of the upper die; 4-1, cavity of the lower die; DETAILED DESCRIPTION

[0028] A forming method of a two-end three-pronged branch long rod type titanium alloy extrusion, which comprises the following steps:

[0029] 1. Rod material blanking;

[0030] 2. Machining a distribution groove at both ends of the rod material;

[0031] 3. Heating the titanium alloy blank to 40℃ below the phase transition point and calculating the holding time according to the heating specification coefficient of 0.8 min / mm, elongating the middle part of the rod material to form an initial state rod part, and keeping the two end heads unchanged;

[0032] 4. Preheating the tooling of the new end head of the special forming preformed part ( Figures 3-4 ) to ≥350℃ and holding for ≥2h, and utilizing the axisymmetric characteristics of the hexagonal body at both ends of the rod part of the preformed part, forming one corner end of one end of the rod part every 120° rotation during forging, to obtain three corner ends of one end head of the preformed part; utilizing the same method to form the other new end head of the preformed part.

[0033] 5. The initial state rod is drawn, and the blank is obtained, and the diameter of the rod of the blank is the same as that of the forged piece;

[0034] 6. The titanium alloy blank is heated to 40℃ below the phase transition point, and the holding time is calculated according to the heating specification coefficient 0.8min / mm, and the final forming die of the extruded part is heated to above 350℃ and held, and the final forming die comprises an upper die assembly connected with the slider of the press, a lower die assembly connected with the lower structure of the press, and an ejection device; as shown in Figures 1-2 5, the upper die assembly comprises an upper die plate and an upper die, the lower die assembly comprises a lower die plate and a lower die, and the ejection device comprises a top rod and a special-shaped top block;

[0035] 7. The preheated and held die is installed on the press; the inner cavity of the die is uniformly sprayed with organic graphite lubricant; the heat-treated titanium alloy blank is placed in the lower die cavity;

[0036] 8. The slider of the press drives the upper die assembly to move downward, and after the overall cavity of the die is closed, it is pressure-holding for 2min, so that the titanium alloy preformed part is formed in the overall cavity of the die to form an extruded part;

[0037] 9. The slider of the press drives the upper die assembly to move upward; the press ejection cylinder moves upward, so that the overall ejection device moves upward, so that the irregular axisymmetric six-sided body with arc of the extruded part is completely taken out of the lower die cavity, and then taken out; the upper die assembly and the lower die assembly are closed, the fastening bolts connected with the slider of the press and the lower workbench are loosened, the die is unloaded, and the final forming extruded part as shown in Figure 6 is obtained.

[0038] Preferably, the irregular axisymmetric six-sided body of the blank is that the size of every three edges is equal, and the total is divided into two types; one type is a long straight line edge, and the other type is a short straight line edge;

[0039] Preferably, the irregular axisymmetric six-sided body with arc of the final forming extruded part is that the size and shape of every three edges are the same, and the total is divided into two types; one type is a straight line edge, and the other type is an arc line edge; a draft is provided on the similar six-sided surface; and the lower die has a fillet at the edge corner of the two end cavities;

[0040] Preferably, the forged piece has obvious axisymmetric characteristics; the middle rod of the forged piece is relatively long, and needs to be drawn twice, which is convenient for operation;

[0041] Preferably, the tooling of the irregular axisymmetric six-sided body is completely the same as one end of the preformed part;

[0042] Preferably, the parting surface of the forged piece is along the maximum cross-sectional area of the forged piece, and constitutes a very irregular parting surface; the parting surface constitutes a "V" shape; and a flash groove is provided between the parting surfaces of the upper and lower dies;

[0043] The embodiment designs two stages of preforming and final forming, closed die structure and overall ejection device: by using the irregular axisymmetric hexagon tooling and free forging method to form the preforming structure of the forging, the forming method is simple, easy to operate and economical; by using the axisymmetric characteristics of the hexagon at both ends of the forging, during forging, after forming one corner end each time, rotating 120°, forming three corner ends of the hexagon at one end of the forging in turn, using the same method to form the irregular axisymmetric hexagon at the other end of the preformed part, simplifying the operation, good formability and no defects; by using the characteristics of the largest inscribed circle of the irregular axisymmetric hexagon of the preformed part and the characteristics of the largest inscribed circle of the hexagon of the irregular axisymmetric extrusion part with arc in the final forming, the rod part of the extrusion part is formed by two times of elongation, which well controls the flow of metal, the flow line is uniformly distributed and reduces the probability of warping of the rod part of the preformed forging during forming; through the final forming stage, the reasonable design of the draft angle and round corner of the upper die and lower die cavity and the "V" shaped parting surface formed by the upper and lower die, makes the final forming extrusion part easy to fill the die cavity, reasonably distributes the flow of metal, produces perfect flow line and does not produce defects such as warping, easy to form extrusion part and easy to take out. After the deformation of the blank, the size parameters of the extrusion part reach reasonable values, the grains are obviously mechanically refined and the comprehensive performance is significantly improved.

Claims

1. A method for forming a titanium alloy extruded part with three-pronged branches at both ends, characterized in that, include: Bar blanking; The middle part of the rod is drawn out to form the initial rod part of the rough blank, while the two ends remain unchanged; The two ends are extruded and forged using preform tooling to make the cross-section of the ends into an irregular axisymmetric hexagon. The irregular axisymmetric hexagon is an equilateral triangle with its vertex and base corners removed. The central axis of the new end is coaxial with the central axis of the initial rod. The initial rod is elongated to obtain a blank. The diameter of the rod in the blank is the same as the diameter of the rod in the forging. The blank is die-forged, and the metal at the end of the blank flows into the shaped cavity used to form the end of the forging, while the metal at the rod of the blank flows into the cavity used to form the rod of the forging.

2. The method according to claim 1, characterized in that, Before drawing the middle portion of the bar to form the initial rough-shaped bar section, the method further includes: By machining material distribution grooves at both ends of the bar stock, the irregular axisymmetric hexagons at both ends of the forging have sufficient forging volume during preforming.

3. The method according to claim 2, characterized in that, The two ends are extruded and forged using preform tooling, including: Preheat the tooling of the new end of the special forming preform to ≥350℃ and keep it at that temperature for ≥2h. Utilizing the axisymmetric characteristics of the hexagons at both ends of the preform rod, during forging, one corner end of one end of the rod is formed every 120° rotation, resulting in the three corner ends of one end of the preform. The other new end of the preform is formed using the same method.

4. The method according to claim 1, characterized in that, The preform tooling is a standard block with an inverted trapezoidal groove, with the end of the block being inserted into the inverted trapezoidal groove. The angle between the bottom of the groove and the groove wall is 120°.

5. The method according to claim 1, characterized in that, The process from bar stock to blank requires only one firing.

6. The method according to claim 1, characterized in that, Die forging is completed in one heat.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1-6.

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