A high-strength metal alloy thin-wall tube electric-assisted forming process and device

Abstract

The present invention discloses an electrically assisted forming process and device for a high-strength metal alloy thin-walled tube, the device mainly comprising a die sleeve, a terminal, a pulse power supply, a die base, a sealing baffle, a drawing die and a cooling water circulation chamber. The process mainly comprises: firstly, a graphite or aluminum rod fusible metal is introduced into the high-strength metal alloy tube to be drawn, so that it fills the entire interior of the tube, and then a pulse current is introduced into the plastic deformation zone of the thin-walled tube, and at the same time, the cooling device can achieve a good cooling effect. After the processing is completed, a thin-walled tube of corresponding length is cut according to production requirements, and annealing treatment is performed in a vacuum heat treatment furnace. During the forming process, the introduced pulse current can improve the material properties, increase the plasticity, and reduce the forming force during deformation. The filling metal in the thin-walled tube is recycled after annealing, which is more in line with economic requirements.

Description

Technical Field

[0001] The invention relates to the technical field of tube forming, and in particular to an electric-assisted forming process and device for a high-strength metal alloy thin-wall tube. Background Art

[0002] Drawing is a plastic processing method that reduces the cross-sectional area of ​​metal by passing it through a die with a tapered hole. Drawing can be used to process wires and tubes of various cross-sections to obtain high precision and high surface quality. There is no waste of material during the forming process. In today's era of resource-saving development, drawing technology is becoming more and more important.

[0003] The current tube forming process is prone to cracking or even breaking when the deformation is large for some metals with low plasticity and high degree of work hardening. Introducing electric current into the plastic forming process of the material can effectively reduce the forming force of the material and significantly improve the microstructure and mechanical properties of the material. Compared with the traditional tube forming process, it has significant advantages and provides a very promising method for the processing problem of difficult-to-deform materials. At present, the electric-assisted forming process has been applied to drawing forming, but most of them are electric-assisted drawing of wires, and there are few studies on the electric-assisted drawing process of tubes. Therefore, it is urgent to develop a method for studying the electric-assisted drawing process of thin-walled high-strength metal alloy tubes. Summary of the invention

[0004] The purpose of the present invention is to provide an electric-assisted forming process and device for a high-strength metal alloy thin-walled tube to solve the problems existing in the above-mentioned prior art. The high-strength metal alloy thin-walled tube is subjected to multi-pass drawing by electroplastic forming, thereby improving production efficiency and solving the problem of severe work hardening of the high-strength metal alloy thin-walled tube. The fusible metal recovered during annealing effectively reduces production costs and has better economy.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a high-strength metal alloy thin-wall tube electric-assisted forming process, comprising the following steps:

[0007] Step 1: According to the outer diameter Φ of the high-strength metal alloy tube to be drawn 0 and the target high strength metal alloy pipe outer diameter Φ 目标 , where Φ 目标 =Φ n (n>5), select the drawing die with the corresponding aperture in turn, select Φ 1 , Φ 2 , Φ 3 , ..., Φ n Drawing die;

[0008] Step 2: Put a low melting point metal filler into the high strength metal alloy tube to be drawn, with a gap fit between the two, and fill the gap between the low melting point metal filler and the inner wall of the high strength metal alloy tube to be drawn with graphite powder;

[0009] Step 3, turn on the pulse power supply, set the current size, duty cycle and frequency parameters according to the needs through the pulse power supply, send the high-strength metal alloy tube to be drawn into the drawing die, drive the high-strength metal alloy tube to be uniformly conveyed from left to right through the horizontal rightward pulling force, and perform electroplastic drawing. A cooling device is provided between each pass. The high-strength metal alloy tube is drawn for more than 5 passes, and the total drawing processing rate is greater than 50%, the inner diameter is reduced by 20-70%, the outer diameter is reduced by 40%-90%, and the wall thickness is thinned by 60-95%. After the drawing is completed, turn off the pulse power supply to obtain a high-strength metal alloy thin-walled tube;

[0010] Step 4: After drawing is completed, the high-strength metal alloy thin-walled tube of corresponding length is cut as needed, and placed vertically in a vacuum heat treatment furnace for annealing. The low-melting-point metal filler in the high-strength metal alloy thin-walled tube is melted and flows into the groove of the vacuum heat treatment furnace under the action of gravity for recycling, and the target high-strength metal alloy thin-walled tube is obtained.

[0011] Optionally, the duty cycle of the pulse power supply is set to 20-90%, the frequency is 100-1000HZ, and the output current is 30-1000A.

[0012] Optionally, the annealing temperature is 300-900° C., the annealing time is 0.5-5 h, and air cooling is performed after annealing.

[0013] Optionally, the low melting point metal filler is pure aluminum or an aluminum alloy.

[0014] Optionally, the vacuum heat treatment furnace includes a furnace wall, a groove with a top opening is provided at the bottom of the furnace wall, a cross frame is provided above the groove, and the cross frame is used to evenly and vertically place the high-strength metal alloy thin-walled tubes to be annealed.

[0015] The present invention also provides an electrically assisted forming device for high-strength metal alloy thin-walled tubes, comprising a drawing die, the inner diameter of which gradually decreases from left to right, and a die base is fixedly connected to both ends of the drawing die, the die base comprising a first die base and a second die base, the inner diameter of the first die base is the same as the inner diameter of the left end of the drawing die, and the inner diameter of the second die base is the same as the inner diameter of the right end of the drawing die; the first die base and the second die base are respectively connected to a terminal, and the two terminals are respectively connected to the positive and negative poles of a pulse power supply; the drawing die is covered with a die base, and the two ends of the die base are respectively fixedly connected to the first die base and the second die base; a cooling water circulation cavity is embedded in the die base, and sealing baffles are provided at both ends of the cooling water circulation cavity, and the sealing baffles are fixed to the drawing die by bolts.

[0016] Optionally, the upper end of the cooling water circulation chamber is connected to a water inlet passing through the mold base, and the lower end of the cooling water circulation chamber is connected to a water outlet passing through the mold base, and the water inlet and the water outlet are respectively connected to an external circulating cold water tank.

[0017] Optionally, the sealing baffle is a circular ring structure, and the bolts are distributed in a circular pattern on the sealing baffle.

[0018] Compared with the prior art, the present invention has achieved the following technical effects:

[0019] The present invention passes a pulse current into the plastic deformation zone of the high-strength metal alloy thin-walled tube drawing, effectively reducing the forming force of the material, reducing the work hardening rate, improving the metal plasticity, improving the formability of the high-strength metal, and solving the problem that the high-strength metal alloy thin-walled tube is difficult to form; the high-strength metal alloy thin-walled tube is drawn in multiple passes by electroplastic drawing, and no annealing is required in the middle, which improves the production efficiency. The fusible metal recovered during annealing after the drawing is completed can be effectively recovered, reducing the production cost and having better economy; a cooling water circulation chamber is provided in the drawing die, which reduces the die temperature and is beneficial to improving the surface performance of the high-strength metal alloy thin-walled tube and the service life of the die. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic structural diagram of the electric-assisted forming device for high-strength metal alloy thin-walled tubes of the present invention;

[0022] Figure 2 It is a schematic structural diagram of the vacuum heat treatment furnace of the present invention.

[0023] Among them: 1. high-strength metal alloy tube; 2. low-melting-point metal filler; 3. mold sleeve; 4. terminal; 5. mold base; 6. pulse power supply; 7. cooling water circulation chamber; 8. drawing die; 9. sealing baffle; 10. furnace wall; 11. high-strength metal alloy thin-walled tube; 12. molten metal; 13. groove. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The purpose of the present invention is to provide an electric-assisted forming process and device for a high-strength metal alloy thin-walled tube to solve the problems existing in the above-mentioned prior art. The high-strength metal alloy thin-walled tube is subjected to multi-pass drawing by electroplastic forming, thereby improving production efficiency and solving the problem of severe work hardening of the high-strength metal alloy thin-walled tube. The fusible metal recovered during annealing effectively reduces production costs and has better economy.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1 and 2As shown, the high-strength metal alloy thin-walled tube electrically assisted forming device provided by the present invention is provided with a die sleeve 3, a terminal 4, a die base 5, a pulse power supply 6, a cooling water circulation chamber 7, a drawing die 8 and a sealing baffle 9 in sequence in the drawing direction: the die sleeve 3 includes a first die sleeve and a second die sleeve, and the first die sleeve and the second die sleeve are respectively provided with two positive and negative terminal posts 4, and the two terminal posts 4 are respectively connected to the positive and negative poles of the pulse power supply 6; the cooling water circulation chamber 7 is embedded in the die base 5, and the upper end of the cooling water circulation chamber 7 is connected to the water inlet, and the lower end is connected to the water outlet. The water inlet and the water outlet of the cooling water circulation chamber 7 are externally connected to the circulating cold water tank, and together constitute a closed cooling circulation system, and sealing baffles 9 of annular structure are provided at both ends of the cooling water circulation chamber 7, and the sealing baffle 9 is fixed to the drawing die 8 by bolts, and the bolts are distributed in a circle at the sealing baffle 9. The high-strength metal alloy tube 1 is subjected to a horizontal rightward pulling force, thereby driving the high-strength metal alloy tube 1 to be transported from left to right at a certain speed. After the drawing is completed, the high-strength metal alloy thin-walled tube 11 of corresponding length is cut according to production needs, and annealing is carried out in a vacuum heat treatment furnace. The aluminum rod in the high-strength metal alloy thin-walled tube 11 is melted and flows into the molten metal 12 in the groove 13 under the action of gravity for recycling, and the target high-strength metal alloy thin-walled tube 11 is obtained.

[0028] Based on the above forming device, the present invention provides a high-strength metal alloy thin-wall tube electric-assisted forming process, comprising the following steps:

[0029] Step 1: According to the outer diameter of the high-strength metal alloy tube to be drawn, 0 and the target high-strength metal alloy pipe outer diameter Φ 目标 , where Φ 目标 =Φ n (n>5), select the drawing die with the corresponding aperture in turn, select Φ 1 , Φ 2 , Φ 3 , ..., Φ n Drawing die;

[0030] Step 2: Put the low-melting-point metal filler 2 into the high-strength metal alloy tube to be drawn, with a gap fit between the two, and fill the gap between the low-melting-point metal filler 2 and the inner wall of the high-strength metal alloy tube to be drawn with graphite powder;

[0031] Step 3, turn on the pulse power supply, set the current size, duty cycle and frequency parameters according to the needs through the pulse power supply, send the high-strength metal alloy tube to be drawn into the drawing die, drive the high-strength metal alloy tube to be uniformly conveyed from left to right through the horizontal rightward pulling force, and perform electroplastic drawing. A cooling device is provided between each pass. The high-strength metal alloy tube is drawn for more than 5 passes, and the total drawing processing rate is greater than 50%, the inner diameter is reduced by 20-70%, the outer diameter is reduced by 40%-90%, and the wall thickness is thinned by 60-95%. After the drawing is completed, turn off the pulse power supply to obtain a high-strength metal alloy thin-walled tube;

[0032] Step 4. After the drawing is completed, the high-strength metal alloy thin-walled tube of corresponding length is cut as needed, and is placed vertically in a vacuum heat treatment furnace for annealing. The vacuum heat treatment furnace includes a furnace wall 10, and a groove 13 with a top opening is arranged at the bottom of the furnace wall 10. A cross frame is arranged above the groove 13, and the cross frame is used to evenly and vertically place the high-strength metal alloy thin-walled tube to be annealed; the low-melting-point metal filler 2 in the high-strength metal alloy thin-walled tube is melted and flows into the groove 13 of the vacuum heat treatment furnace under the action of gravity to form a molten metal 12 for recycling, and the target high-strength metal alloy thin-walled tube is obtained.

[0033] Embodiment 1

[0034] A high-strength metal alloy thin-walled tube electric-assisted drawing device is used to prepare a 410 stainless steel thin-walled tube. The 410 stainless steel tube with an outer diameter of 20 mm and a wall thickness of 4 mm is electroplastically drawn until the 410 stainless steel tube is drawn to a thin-walled tube with an outer diameter of 10 mm and a wall thickness of 1 mm. A total of 12 drawing passes are performed, and the average drawing die diameter of each pass is Φ 1 =19.5mm; Φ 2 =19mm; Φ 3 =18.5mm; Φ 4 =18mm; Φ 5 =17.4mm; Φ 6 =16.8mm; Φ 7 =16.1mm; Φ 8 =15.3mm; Φ 9 =14.5mm; Φ 10 =13.5mm; Φ 11 =12mm; Φ 12 =10mm, the total drawing processing rate is 86%, the specific steps are as follows:

[0035] Step 1: According to the outer diameter of the 410 stainless steel tube to be drawn, 0 And the outer diameter of the target 410 stainless steel pipe Φ 目标 , where Φ 目标 =Φ 12, select the drawing die with the corresponding aperture in turn, select Φ 1 , Φ2, Φ 3 , ..., Φ 12 Drawing die;

[0036] Step 2: Place a 10mm diameter fusible metal aluminum rod into the 410 stainless steel tube to be drawn, and fill the gap between the aluminum rod and the inner wall of the metal tube with graphite powder to fill the entire interior of the steel tube;

[0037] Step 3, turn on the pulse power supply, set the duty cycle to 50%, the frequency to 300HZ, and the output current to 100A according to the needs of the pulse power supply, and send the 410 stainless steel pipe to be drawn into the drawing die. The 410 stainless steel pipe is subjected to a horizontal rightward pulling force. The 410 stainless steel pipe is conveyed from left to right at 50mm / s for electroplastic drawing. A cooling device is provided between each pass, and cooling water is introduced into the cooling water cavity in the cooling device. After the drawing is completed, turn off the pulse power supply;

[0038] Step 4: After drawing, cut the corresponding length of 410 stainless steel thin-walled tube according to production needs. At the same time, the work hardening is serious during drawing, and the 410 stainless steel thin-walled tube needs to be annealed. In the vacuum heat treatment furnace, the vacuum annealing heat treatment temperature is 750°C, the annealing time is 2h, and the annealing is air-cooled after annealing. The aluminum rod in the 410 stainless steel thin-walled tube melts and flows into the groove by itself under the action of gravity for recycling and reuse, and the target thin-walled tube is obtained.

[0039] Embodiment 2

[0040] The difference from the first embodiment is that the drawing object is a TC4 titanium alloy tube, the filler is a magnesium alloy AZ31, and the drawn TC4 titanium alloy thin-walled tube can be directly placed in a vacuum heat treatment furnace for annealing.

[0041] A high-strength metal alloy thin-walled tube electric-assisted drawing device is used to prepare a TC4 titanium alloy thin-walled tube with an outer diameter of 30 mm and a wall thickness of 8 mm. The TC4 titanium alloy tube is electroplastically drawn until the TC4 titanium alloy tube is drawn to a thin-walled tube with an outer diameter of 6 mm and a wall thickness of 0.8 mm. A total of 17 drawing passes are performed, and the average drawing die diameter of each pass is Φ 1 =29mm, Φ 2 =27mm, Φ 3 =25mm,Φ 4 =24.5mm,Φ 5 =23.5mm,Φ 6 =22mm, Φ 7 =21mm,Φ 8 =20mm,Φ 9 =18.5mm,Φ 10 =16mm,Φ 11=15mm,Φ 12 =14mm,Φ 13 =13.5mm,Φ 14 =11mm,Φ 15 =10mm,Φ 16 =8.5mm,Φ 17 =8mm, the specific steps are as follows:

[0042] Step 1: According to the outer diameter Φ0 of the TC4 titanium alloy tube to be drawn and the outer diameter Φ 目标 , where Φ 目标 =Φ 17 , select the drawing die with the corresponding aperture in turn, select Φ 1 , Φ 2 , Φ 3 , ..., Φ 17 Drawing die;

[0043] Step 2: Pass an AZ31 magnesium alloy rod with a diameter of 12 mm into the TC4 titanium alloy tube to be drawn, and fill the gap between the AZ31 rod and the inner wall of the metal tube with graphite powder to fill the entire interior of the TC4 titanium alloy tube;

[0044] Step 3, turn on the pulse power supply, set the duty cycle to 40-70%, the frequency to 100-600HZ, and the output current to 80-600A according to the needs of the pulse power supply, and send the TC4 titanium alloy tube to be drawn into the drawing die. The TC4 titanium alloy tube is subjected to a horizontal rightward pulling force. The TC4 titanium alloy tube is conveyed from left to right at 160mm / s for electroplastic drawing. A cooling device is provided between each pass, and cooling water is introduced into the cooling water cavity in the cooling device. After the drawing is completed, turn off the pulse power supply;

[0045] Step 4: After drawing, cut the corresponding length of TC4 titanium alloy thin-walled tube according to production needs, remove the graphite by tools or knocking, and anneal the TC4 titanium alloy thin-walled tube because of severe work hardening during drawing. In a vacuum heat treatment furnace, the temperature of vacuum annealing heat treatment is 800°C, the annealing time is 1.5h, and air cooling is performed after annealing. The magnesium alloy rod in the TC4 titanium alloy thin-walled tube melts and flows into the groove by itself under the action of gravity for recycling and reuse, and the target thin-walled tube is obtained.

[0046] In the description of the present invention, it should be noted that the terms "center", "top", "bottom", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0047] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A high-strength metal alloy thin-wall tube electrically assisted forming process, characterized in that: The steps include: Step 1: According to the outer diameter Φ0 of the high-strength metal alloy tube to be drawn and the outer diameter Φ 目标 , select the drawing die with corresponding aperture in turn; Step 2: Put a low melting point metal filler into the high strength metal alloy tube to be drawn, with a gap fit between the two, and fill the gap between the low melting point metal filler and the inner wall of the high strength metal alloy tube to be drawn with graphite powder; Step 3, turn on the pulse power supply, set the current size, duty cycle and frequency parameters according to the needs through the pulse power supply, send the high-strength metal alloy tube to be drawn into the drawing die, and drive the high-strength metal alloy tube to be uniformly conveyed from left to right through the horizontal rightward pulling force to perform electroplastic drawing. A cooling device is provided between each pass. After the drawing is completed, turn off the pulse power supply to obtain a high-strength metal alloy thin-walled tube; the duty cycle of the pulse power supply is set to 20-90%, the frequency is 100-1000HZ, and the output current is 30-1000A; Step 4. After drawing is completed, the high-strength metal alloy thin-walled tube of corresponding length is cut as needed, and placed vertically in a vacuum heat treatment furnace for annealing. The low-melting-point metal filler in the high-strength metal alloy thin-walled tube melts and flows into the groove of the vacuum heat treatment furnace under the action of gravity for recycling, and the target high-strength metal alloy thin-walled tube is obtained; the annealing temperature is 300-900°C, the annealing time is 0.5-5h, and air cooling is performed after annealing.

2. The high-strength metal alloy thin-wall tube electrically assisted forming process according to claim 1, characterized in that: The low melting point metal filler is pure aluminum or aluminum alloy.

3. The high-strength metal alloy thin-wall tube electrically assisted forming process according to claim 1, characterized in that: The vacuum heat treatment furnace comprises a furnace wall, a groove with an open top is arranged at the bottom of the furnace wall, a horizontal frame is arranged above the groove, and the horizontal frame is used for evenly and vertically placing high-strength metal alloy thin-walled tubes to be annealed.

4. A high-strength metal alloy thin-walled tube electrically assisted forming device applied to the high-strength metal alloy thin-walled tube electrically assisted forming process according to any one of claims 1 to 3, characterized in that: It includes a drawing die, the inner diameter of which gradually decreases from left to right, and a die base is fixedly connected at both ends of the drawing die, the die base includes a first die base and a second die base, the inner diameter of the first die base is the same as the inner diameter of the left end of the drawing die, and the inner diameter of the second die base is the same as the inner diameter of the right end of the drawing die; the first die base and the second die base are respectively connected with a terminal, and the two terminals are respectively connected to the positive and negative poles of the pulse power supply; the drawing die is covered with a die base, and the two ends of the die base are respectively fixedly connected to the first die base and the second die base; a cooling water circulation cavity is embedded in the die base, and sealing baffles are provided at both ends of the cooling water circulation cavity, and the sealing baffles are fixed to the drawing die by bolts; the upper end of the cooling water circulation cavity is connected to a water inlet passing through the die base, and the lower end of the cooling water circulation cavity is connected to a water outlet passing through the die base, and the water inlet and the water outlet are respectively connected to a circulating cold water tank; the sealing baffle is a circular ring structure, and the bolts are distributed circumferentially on the sealing baffle.

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