Pulse current assisted metal tube drawing forming device

Abstract

The application belongs to metal drawing forming device, specifically a kind of pulse current assisted metal pipe drawing forming device, including base, fixed on the drawing frame of base, install the electric push cylinder in drawing frame one end, with the connecting head of electric push cylinder telescopic end connection, with the clamp for clamping pipe blank connected with connecting head, install the drawing die in drawing frame front end, fixed in the core rod fixed platform core rod, set up in the core rod rear end core rod connecting part, seal cover and with the gas cylinder that communicates with seal cover, and current output device, control console;Device is equipped with first loop and second loop, first loop is used to test current output, and second loop is used for pulse current output;The one end of pipe blank is provided with electrically conductive sleeve, and the electrically conductive sleeve is fixedly arranged on the core rod connecting part, the resistance of test current measurement loop is measured, and the preset current pulse output is corresponded, so that the equipment can independently switch pulse current parameter.

Description

Technical Field

[0001] This invention pertains to metal drawing and forming apparatuses, specifically a pulse current-assisted metal tube drawing and forming apparatus. Background Technology

[0002] Metal tube drawing typically involves reducing the outer diameter of the tube under tension by drawing it through a drawing die, and using a mandrel to control the inner diameter. During the drawing process, there is strong friction and contact compressive stress between the material and the die. This is especially true for high-strength or work-hardened materials such as stainless steel, which can easily lead to problems such as high drawing force and high energy consumption.

[0003] In recent years, ideas such as electric-assisted forming and electric pulse-assisted forming have emerged to reduce deformation resistance. In pulse current-assisted drawing forming, when a pulse current is passed into the material, the drifting electrons exert a thrust on the dislocations, that is, generate an electron wind, which can reduce the flow stress of the metal and increase its plasticity, thereby reducing the forming force.

[0004] Different workpieces require different pulse current density, pulse width, and frequency adjustments. The parameters need to be adjusted after each batch of workpieces is drawn. For example, copper pipes used for air conditioning refrigeration, stainless steel pipes used for gas transmission, and drawn aluminum pipes for automobiles require different pulse current parameters for each batch of pipes.

[0005] Therefore, how to enable the equipment to automatically switch pulse current parameters for tube blanks with different wall thicknesses and materials is a problem that needs to be solved by existing technologies. Summary of the Invention

[0006] The purpose of this invention is to provide a pulse current-assisted metal tube drawing forming device, including a base, a drawing frame fixed on the base, an electric pusher cylinder installed at one end of the drawing frame, a connector connected to the telescopic end of the electric pusher cylinder, a clamp connected to the connector and used to hold the tube blank, a drawing die installed at the front end of the drawing frame, a connecting flange and an end cap flange used to position and press the drawing die, a mandrel fixed at one end to the mandrel fixing table, a mandrel connecting part set at the rear end of the mandrel, a sealing cover set outside the drawing frame and the drawing die, a gas cylinder communicating with the sealing cover, a current output device, and a control console;

[0007] The fixture is equipped with a conductive part that contacts the outer wall of the tube blank, and the current output device is electrically connected to the conductive part through a wire.

[0008] The device is equipped with a first circuit and a second circuit. The first circuit is used for testing current output, and the second circuit is used for pulse current output.

[0009] A conductive sleeve is provided at one end of the tube blank, and the conductive sleeve is fixedly mounted on the mandrel connection part.

[0010] Furthermore, the first circuit is used for circuit resistance detection after the material loading is completed.

[0011] Furthermore, the second circuit is used for the forming pulse output during the drawing process.

[0012] Furthermore, the conductive sleeve contacts the outer wall of the tube blank via a spring.

[0013] Furthermore, the outer surface of the mandrel is coated with insulating varnish, and the mandrel only has a conductive area reserved at the head for contact with the tube blank.

[0014] Furthermore, the fixture uses a conductive part to conduct electricity, and the rest of the fixture is insulated from the contact area of ​​the drawing frame.

[0015] Furthermore, the wire between the current output device and the conductive part of the clamp is a helical spring wire.

[0016] Furthermore, the sealing cover is made of internally visible material, and the gas cylinder continuously supplies inert gas into the sealing cover during operation, so that an inert gas atmosphere is formed in the drawing area.

[0017] Furthermore, during the resistance measurement phase, the control console controls the current output device to output the test current.

[0018] Furthermore, after the fixture is in place, the control console performs a circuit switch, causing the current output device to output pulse current according to the locked pulse current parameters.

[0019] The beneficial effects achieved by the present invention using the above structure are as follows:

[0020] (1) The equivalent resistance of the circuit is measured through the first circuit, and the control console matches the resistance with the pre-established "resistance-pulse parameter mode" correspondence, automatically locking the pulse current parameter of this pull-out, reducing the error of manual parameter selection.

[0021] (2) The outer surface of the core rod is coated with insulating varnish, and only the head is reserved for the conductive area. This makes the two key contacts of the resistance measurement circuit stable as “core rod head and inner wall of tube blank” and “conductive sleeve and outer wall of tube blank”, respectively. The effective measured length between the two contacts is basically fixed, reducing the resistance fluctuation caused by the change of contact point position and improving the reliability of resistance identification. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the pulse current-assisted metal tube drawing and forming device of the present invention.

[0023] Figure 2 This is a cross-sectional view of the drawing forming apparatus of the present invention.

[0024] Figure 3 This is a schematic diagram of the fixture of the present invention.

[0025] Figure 4 This is a cross-sectional view of the drawing die of the present invention.

[0026] Figure 5 This is a schematic diagram showing the connection between the first circuit resistance measurement and the second circuit pulse output of the present invention.

[0027] Figure 6 This is a schematic diagram of the pulse current parameter switching control process based on resistance identification according to the present invention.

[0028] The components are as follows: 1. Base; 2. Drawing frame; 3. Electric pusher cylinder; 4. Connector; 5. Clamp; 6. Groove; 7. Chuck; 8. Rack; 9. Gear; 10. Conductive part; 11. Drawing die; 12. Die sleeve; 13. Connecting flange; 14. End cover flange; 15. Mandrel fixing platform; 16. Mandrel; 17. Mandrel connecting part; 18. Tube blank; 19. Conductive sleeve; 20. Sealing cover; 21. Gas cylinder; 22. Current output device; 23. Control console; 24. First circuit; 25. Second circuit. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] like Figures 1 to 5 As shown, this embodiment provides a pulse current-assisted metal tube drawing forming device, including a base 1, a drawing frame 2, an electric push cylinder 3, a connector 4, a clamp 5, a drawing die 11, a die sleeve 12, a connecting flange 13, an end cap flange 14, a mandrel fixing table 15, a mandrel 16, a mandrel connecting part 17, a current output device 22, and a control console 23.

[0031] A sealing cover 20 is installed on the outside of the device. The sealing cover 20 is connected to the gas cylinder 21 and is used to replenish inert gas to the drawing area to reduce the risk of surface oxidation of the tube blank 18 during the energization and deformation process.

[0032] The base 1 is used to support the whole machine and provide an installation reference. The drawing frame 2 is fixedly installed on the base 1. The electric push cylinder 3 is installed at one end of the drawing frame 2. The telescopic end of the electric push cylinder 3 is connected to the connector 4. The connector 4 is connected to the clamp 5 and is used to drive the clamp 5 to move back and forth linearly along the drawing direction, thereby applying axial traction force to the tube blank 18.

[0033] A drawing die 11 is installed at the front end of the drawing machine frame 2. The drawing die 11 is positioned, clamped, and quickly disassembled through the connecting flange 13 and the end cover flange 14.

[0034] like Figure 4 As shown, a die sleeve 12 can be provided on the outside of the drawing die 11 to enhance assembly positioning and stress stability.

[0035] The tube blank 18 passes through the drawing die 11 along the drawing direction under the traction of the clamp 5. Under the radial constraint of the drawing die 11, it undergoes plastic deformation, thereby reducing the outer diameter and adjusting the wall thickness.

[0036] The mandrel 16 passes through the center of the drawing die 11, and one end of the mandrel 16 is fixed on the mandrel fixing table 15, so that the mandrel 16 remains axially stable relative to the drawing frame 2.

[0037] like Figure 2 As shown, the mandrel 16 and the drawing die 11 form an internal and external co-constraint, thereby controlling the inner diameter and wall thickness of the tube blank 18 during the drawing process. The mandrel connecting part 17 is located at the rear end of the mandrel 16 and is used to connect with the assembly structure and the electrical connection structure.

[0038] This device applies an electrical pulse to the tube blank 18 via the current output device 22 to assist the material deformation behavior during the drawing deformation process.

[0039] like Figure 3 As shown, in order to ensure that the current can stably enter the tube blank 18 and to avoid the current from entering the drawing frame 2 and other structural components as much as possible, the clamp 5 is configured to have both clamping and electrode functions.

[0040] The clamp 5 includes a groove 6, a chuck 7, a rack 8 and a gear 9. The rack 8 moves under the action of the drive, and the gear 9 drives the chuck 7 to open and close, thereby clamping or releasing the end of the tube blank 18.

[0041] A conductive part 10 is provided on the inner side of the chuck 7. The conductive part 10 contacts the outer wall of the tube blank 18, so that the chuck 5 has the function of conducting an electric electrode while holding the tube blank 18.

[0042] The fixture 5 uses the conductive part 10 to conduct electricity, while the rest of the part is non-conductive and forms an insulating isolation with the contact area with the frame.

[0043] The current output device 22 is electrically connected to the conductive part 10 of the clamp 5 via a wire, so that the pulse current can be input from the clamp 5 to the tube blank 18.

[0044] The clamp 5 needs to move back and forth during the pulling process, so a spiral spring wire is used to maintain sufficient tension during the stretching process to avoid the wire from getting tangled.

[0045] like Figure 2As shown, a sealing cover 20 is provided outside the area where the drawing machine frame 2 and the drawing die 11 are located, and the sealing cover 20 is connected to the gas cylinder 21.

[0046] During operation, the gas cylinder 21 continuously supplies inert gas into the sealing cover 20, so that an inert gas atmosphere is formed in the drawing area. When the pulse current is applied and the local temperature rises, the oxidation effect of oxygen in the air on the surface of the tube blank 18 can be reduced, and the surface quality of the tube can be improved. The sealing cover 20 is preferably made of internally visible material, which makes it easy to observe the drawing state and abnormal conditions.

[0047] like Figure 1 , Figure 5 , Figure 6 As shown, this device is equipped with a first circuit 24 and a second circuit 25, and the switching between the two circuits is achieved through the control console 23;

[0048] During the resistance measurement stage, only the first circuit 24 is allowed to conduct, and during the pulse pull-out stage, only the second circuit 25 is allowed to conduct, in order to avoid large current pulses entering the measurement branch and causing measurement distortion.

[0049] The first circuit 24 is used for circuit resistance detection after the material is loaded. The control console 23 controls the current output device 22 to output a test current and collects the circuit voltage to obtain the circuit equivalent resistance R. The control console 23 matches the resistance R with the pre-established resistance and pulse parameter mode, outputs the identification result and locks the pulse current parameter of this pull-out.

[0050] The second circuit 25 is used for forming pulse output during the drawing process. After the fixture 5 is clamped in place, the control console 23 cuts off the first circuit 24 and connects the second circuit 25. The current output device 22 outputs pulse current in the locked pulse mode, so that the current passes through the drawing deformation area and works in coordination with the electric push cylinder 3 to pull and form, thereby realizing pulse current assisted drawing and forming.

[0051] To ensure that the measured resistance can stably reflect the differences in electrical properties of the tube blank 18 and to avoid resistance fluctuations caused by changes in the contact point position, this device constructs two relatively fixed metal contacts during the resistance measurement stage and fixes the length being measured.

[0052] like Figure 1 and Figure 5 As shown, a conductive sleeve 19 is provided at one end of the tube blank 18. The spring of the conductive sleeve 19 contacts the outer wall of the tube blank 18, serving as the common return end of the resistance measurement circuit and the pulse circuit. The conductive sleeve 19 is fixedly mounted on the mandrel connection part 17, so that the contact position of the conductive sleeve 19 with the tube blank 18 is stable each time.

[0053] Meanwhile, insulating varnish is applied to the outer surface of the core rod 16 so that the core rod 16 only has a pre-reserved conductive area at the head; after the tube blank 18 is fed into the core rod 16, the conductive position between the core rod 16 and the tube blank 18 is limited to the fixed contact area between the head of the core rod and the inner wall of the tube blank 18, so as to avoid random multi-point conductive along the length of the core rod 16.

[0054] Therefore, the two key contacts of the resistance measurement circuit are stabilized as "the head of the mandrel 16 and the inner wall of the tube blank 18" and "the conductive sleeve 19 and the outer wall of the tube blank 18", respectively. The effective measured length between the two contacts is basically fixed, the measured resistance R is more stable, and it is more suitable as a resistance identification input, thereby realizing the automatic switching of pulse current parameters.

[0055] Through the above structure and process, this device achieves engineering coupling of the basic mechanical constraints of drawing forming and the energy input of electric pulse assisted forming within the same equipment. On the one hand, it utilizes the drawing frame 2, drawing die 6, mandrel 8 and electric push cylinder 3 to form a repeatable drawing forming function; on the other hand, it forms a stable conductive path through the clamp 5 and conductive sleeve 10 and provides a protective atmosphere with the sealing cover 15; and then automatically switches the pulse formula through the resistance measured by the first circuit 13 to reduce the process fluctuations caused by the uncertainty of manual selection and contact.

[0056] The above description is merely a specific embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications, equivalent substitutions, or improvements made to the above embodiments without departing from the technical concept of the present invention should fall within the protection scope of the present invention. The protection scope of the present invention is determined by the scope defined in the claims, and the specification and drawings can be used to interpret the claims.

Claims

1. A pulse current-assisted metal tube drawing forming apparatus, characterized by, The device includes a base, a drawing frame fixed on the base, an electric pusher cylinder installed at one end of the drawing frame, a connector connected to the telescopic end of the electric pusher cylinder, a clamp connected to the connector and used to hold the tube blank, a drawing die installed at the front end of the drawing frame, a connecting flange and an end cap flange used to position and press the drawing die, a mandrel fixed at one end to the mandrel fixing table, a mandrel connecting part set at the rear end of the mandrel, a sealing cover set on the outside of the drawing frame and the drawing die, a gas cylinder communicating with the sealing cover, a current output device, and a control console. The fixture is equipped with a conductive part that contacts the outer wall of the tube blank, and the current output device is electrically connected to the conductive part through a wire so that the pulse current can be input from the fixture to the tube blank. The device is equipped with a first circuit and a second circuit. The first circuit is used for circuit resistance detection after the material is loaded. The control console controls the current output device to output a test current and collects the circuit voltage to obtain the circuit equivalent resistance R. The control console matches the resistance R with the pre-established resistance and pulse parameter mode, outputs the identification result and locks the pulse current parameter for this pull-out. The second circuit is used for forming pulse output during the drawing process. After the fixture is clamped in place, the control console cuts off the first circuit and connects the second circuit. The current output device outputs pulse current according to the locked pulse mode, so that the current passes through the drawing deformation area and works in coordination with the electric push cylinder to achieve pulse current assisted drawing forming. A conductive sleeve is provided at one end of the tube blank. The conductive sleeve is fixedly installed on the mandrel connection part. The conductive sleeve contacts the outer wall of the tube blank through a spring. The outer surface of the mandrel is coated with insulating varnish. The mandrel only has a conductive area reserved at the head for contact with the tube blank.

2. The pulsed current assisted metal tube drawing forming device according to claim 1, wherein, The fixture is powered by a conductive part, and the rest of the fixture is insulated from the contact area of ​​the drawing frame.

3. The pulse current-assisted metal tube drawing and forming device according to claim 1, characterized in that, The wire between the current output device and the conductive part of the clamp is a helical spring wire.

4. The pulse current-assisted metal tube drawing and forming device according to claim 1, characterized in that, The sealing cover is made of internally visible material. During operation, the gas cylinder continuously supplies inert gas into the sealing cover, creating an inert gas atmosphere in the drawing area.

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