Current-assisted blank and die coordinated temperature control forming device and hot forming method

Abstract

The present invention discloses a current-assisted blank and die collaborative temperature control forming device and hot forming method. The device utilizes the Joule heating effect and electroplastic effect generated by pulse current passing through the metal to achieve rapid heating of the metal sheet and improve the plastic deformation ability of the alloy. At the same time, the flow effect of the pulse current around the rounded corners of the metal sheet die cavity also increases the temperature there, which can improve the forming limit of the material. In addition, based on the Joule heating effect, the designed upper and lower strip-shaped auxiliary plates are quickly heated by independent power supplies. This not only avoids the rapid cooling phenomenon after the metal sheet contacts the cold die, but also realizes the active control and adjustment of the temperature of the upper and lower auxiliary plates. The comprehensive utilization of the rapid heating and high plastic deformation ability of the metal sheet assisted by current, as well as the design concept and tooling structure of the upper and lower forming auxiliary plates with independent temperature control and adjustment, makes this patent creative and novel in the field of high-efficiency, high-quality, low-energy, and low-cost precision forming of thin-walled metal components.

Description

Technical Field

[0001] The present invention relates to the technical field of precision plastic forming of thin-walled components, and in particular to a current-assisted blank and die coordinated temperature control forming device and a hot forming method. Background Art

[0002] Titanium alloys and high-temperature alloys are widely used in the hot-end structural components of aircraft engines due to their good high-temperature strength, corrosion resistance, and oxidation resistance. Based on the stringent requirements of aircraft engine processing and assembly, thin-walled components of such alloys must have stable and precise dimensions and shapes. However, due to their inherent characteristics such as high room temperature deformation resistance and low plastic forming ability, hot forming methods are currently commonly used to achieve the precise forming of large-scale, complex thin-walled components.

[0003] In traditional hot forming processes, a heating furnace is required to heat the mold and the formed part simultaneously. This not only leads to long manufacturing cycles, low forming efficiency, short mold life, high energy consumption, and high production costs, but also limits the size of the formed part by the size of the heating furnace. Self-resistance heating forming technology, which uses pulsed current to pass through the metal to generate Joule heating to achieve rapid heating of the metal sheet, and current-assisted forming technology, which uses the electroplastic effect to promote plastic deformation of the metal, are effective methods for achieving rapid heating of the metal sheet and improving production efficiency. However, the metal sheet is thin and has low heat content. When it comes into contact with the relatively low-temperature forming mold, its heat will quickly transfer to the forming mold, causing the local temperature of the metal sheet to drop rapidly. Therefore, it is difficult to accurately control its forming process, making it difficult to ensure stable forming quality of the part. Summary of the Invention

[0004] In order to solve the above technical problems, a current-assisted blank and die coordinated temperature control forming device and hot forming method are proposed. The specific technical solutions are as follows:

[0005] A current-assisted blank and die cooperative temperature-controlled forming device comprises a punch, a punch insulation layer, an upper auxiliary plate electrode, an upper auxiliary plate, an upper insulation layer of a blank holder, a blank holder, a lower insulation layer of a blank holder, a forming electrode, a lower auxiliary plate, a lower auxiliary plate electrode, a die insulation layer, a die, and a temperature-measuring thermocouple;

[0006] The male mold and female mold molding surfaces are respectively provided with a male mold insulation and heat insulation layer and a female mold insulation and heat insulation layer;

[0007] The lower end of the male mold insulation layer is provided with a pressure ring, the upper end of the pressure ring is provided with an upper pressure ring insulation layer, and the lower end is provided with a lower pressure ring insulation layer;

[0008] The upper auxiliary plate is arranged at the lower end of the upper auxiliary plate electrode;

[0009] The upper auxiliary plate is installed on the surface of the insulating and heat-insulating layer of the punch, and the position of the upper auxiliary plate is opposite to the surface of the punch, and the upper auxiliary plate electrode is installed between the upper auxiliary plate and the insulating and heat-insulating layer of the punch, and the upper auxiliary plate and the upper auxiliary plate electrode are fastened to the punch by bolts or mechanical connections;

[0010] The lower auxiliary plate and the lower auxiliary plate electrode are installed on the surface of the insulating and heat-insulating layer of the die, and their positions correspond to the die surface. The lower auxiliary plate electrode is installed between the lower auxiliary plate and the insulating and heat-insulating layer of the die, and the lower auxiliary plate and the lower auxiliary plate electrode are fastened to the die by bolts or mechanical connection.

[0011] The left and right sides of the upper auxiliary plate electrode and the lower auxiliary plate electrode are respectively connected to the positive and negative poles of the upper and lower auxiliary plate power supplies to form a current loop;

[0012] The forming electrodes are clamped at both ends of the metal sheet to be formed and form a loop with the blank metal sheet;

[0013] The punch and die are fixedly connected to the upper and lower platforms of the hydraulic press through T-slots and clamping mechanisms, and the movement directions of the punch and die are ensured.

[0014] In the current-assisted blank forming device, a preferred embodiment is that the upper auxiliary plate is a metal plate of approximately the same thickness as the convex mold surface, and the cross-section of the auxiliary plate is adjusted based on the mold surface shape to ensure that the cross-sectional area at each location is similar;

[0015] The lower auxiliary plate is a metal plate of approximately the same thickness as the concave mold surface, and the cross-section of the auxiliary plate is adjusted based on the shape of the mold surface to ensure that the cross-sectional area at each location is similar.

[0016] The described current-assisted blank and mold collaborative temperature control forming device, its preferred solution is that the insulating and heat-insulating layer on the punch, die and pressure ring can be an insulating and heat-insulating layer on the surface of the punch and die or a simple ceramic sheet or asbestos gasket with the same mold surface as the mold.

[0017] A current-assisted blank and die coordinated temperature control forming device and a hot forming method, comprising the following steps:

[0018] Step 1: Use laser cutting, wire cutting or water jet cutting to cut the metal sheet into the shape and size to be processed. The forming size is larger than the mold cavity size to ensure the size requirements of the formed part. The extra size on both sides is used for forming electrode clamping and grinding the edges of the metal sheet to remove burrs and other defects.

[0019] Step 2: Apply insulation and heat-insulating coating to the surfaces of the punch, die, and blank holder. By adjusting the treatment parameters, the insulation and heat-insulating coating is evenly distributed and has similar thickness in each part to ensure the forming accuracy of the parts. The coating thickness is between 50µm and 300µm.

[0020] Step 3: Install the punch and die on the upper and lower platforms of the hydraulic press respectively, ensuring that the punch and die are aligned in their center positions, and fix them to the upper and lower platforms of the hydraulic press by tightening bolts so that the punch can achieve mold closing action as the upper platform of the hydraulic press moves;

[0021] Step 4: Install the blank holder on another vertically movable upper platform of the hydraulic press, between the punch and the die, and corresponding to the molding surfaces of the punch and the die;

[0022] Step 5: Install the upper auxiliary plate on the surface of the male mold insulation layer, its position corresponding to the male mold surface, and install the upper auxiliary plate electrode between the upper auxiliary plate and the male mold insulation layer. The left side of the electrode is connected to the positive pole of the upper auxiliary plate power supply, and the right side is connected to the negative pole of the upper auxiliary plate power supply. Ensure that the upper auxiliary plate power supply is turned off during installation;

[0023] Step 6: Install the lower auxiliary plate on the surface of the insulating and heat-insulating layer of the concave mold. Its position corresponds to the concave mold surface. Install the lower auxiliary plate electrode between the lower auxiliary plate and the insulating and heat-insulating layer of the concave mold. The left side of the electrode is connected to the positive pole of the lower auxiliary plate power supply, and the right side is connected to the negative pole of the lower auxiliary plate power supply. Ensure that the power supply of the upper auxiliary plate is turned off during installation.

[0024] Step 7: Install forming electrodes on both sides of the metal sheet blank. The left side of the forming electrode is connected to the positive pole of the forming power supply, and the right side of the forming electrode is connected to the negative pole of the forming power supply. Ensure that the forming power supply is turned off during installation. Then spray lubricant on the surface of the metal sheet blank and place it on the lower auxiliary plate according to the forming position.

[0025] Step 8: Turn on the power supply of the upper auxiliary plate, the forming power supply, and the lower auxiliary plate, and gradually increase the current of each power supply. The temperature distribution of the upper auxiliary plate, the metal sheet blank, and the lower auxiliary plate is regulated by the current. When the upper auxiliary plate, the metal sheet blank, and the lower auxiliary plate gradually heat up to 400°C to 800°C, they are kept at this temperature for 1 minute to 5 minutes.

[0026] Step 9: Start the hydraulic press, move the blank holder downward, and apply a blank holder force to the metal sheet to prevent the metal sheet from wrinkling or other instability during the forming process;

[0027] Step 10: The punch moves downward to press the metal sheet into a thin-walled part with the mold surface, so that the punch, upper auxiliary plate, metal sheet, lower auxiliary plate and die fit tightly together;

[0028] Step 11: Measure the temperature of the metal sheet after forming with a thermocouple, and adjust the temperature of the upper auxiliary plate, the metal sheet, and the lower auxiliary plate by adjusting the current of each power supply. After maintaining the temperature and pressure for 2 to 3 minutes, gradually reduce the current of each power supply until it reaches zero.

[0029] Step 12: Turn off the power switch, start the hydraulic press, lift the blank holder and punch, and take out the formed parts.

[0030] Beneficial effects of the present invention:

[0031] The present invention utilizes the rapid heating and high plastic deformation capabilities of the metal sheet assisted by electric current, as well as the design concept and tooling structure of the upper and lower forming auxiliary plates with independent temperature control and adjustment, making this patent creative and novel in the field of high-efficiency, high-quality, low-energy consumption, and low-cost precision forming of metal thin-walled components.

[0032] 1. It realizes the rapid and efficient heating and temperature rise of metal sheet, which can reduce the deformation resistance of difficult-to-deform metals such as titanium alloys and high-temperature alloys, improve the plastic deformation capacity, and is suitable for hot stamping of plates of different thicknesses and materials;

[0033] 2. It avoids the problem of uncontrollable forming quality caused by the rapid drop in local temperature of the sheet after the hot-formed sheet contacts the normal temperature mold;

[0034] 3. The mold and the metal sheet blank are simultaneously and rapidly heated, and the temperature is coordinated and adjusted, which solves the problem of poor temperature control accuracy of the metal sheet blank during the current-assisted forming process. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the forming device of the present invention;

[0036] Figure 2 Schematic diagram of the forming device in the initial state;

[0037] Figure 3 Schematic diagram of the forming device in the mold closing state.

[0038] In the figure: 1. punch, 2. punch insulation layer, 3. upper auxiliary plate electrode, 4. upper auxiliary plate, 5. upper insulation layer of blank holder, 6. blank holder, 7. lower insulation layer of blank holder, 8. metal sheet, 9. forming electrode, 10. lower auxiliary plate, 11. lower auxiliary plate electrode, 12. die insulation layer, 13. die, 14. temperature measuring thermocouple. DETAILED DESCRIPTION

[0039] The following is combined with Figure 1-3 The present invention is further described in detail with reference to the accompanying drawings and examples.

[0040] Example 1

[0041] A current-assisted blank and die cooperative temperature-controlled forming device comprises a punch, a punch insulation layer, an upper auxiliary plate electrode, an upper auxiliary plate, an upper insulation layer of a blank holder, a blank holder, a lower insulation layer of a blank holder, a forming electrode, a lower auxiliary plate, a lower auxiliary plate electrode, a die insulation layer, a die, and a temperature-measuring thermocouple;

[0042] The male mold and female mold molding surfaces are respectively provided with a male mold insulation and heat insulation layer and a female mold insulation and heat insulation layer;

[0043] The lower end of the male mold insulation layer is provided with a pressure ring, the upper end of the pressure ring is provided with an upper pressure ring insulation layer, and the lower end is provided with a lower pressure ring insulation layer;

[0044] The upper auxiliary plate is arranged at the lower end of the upper auxiliary plate electrode;

[0045] The upper auxiliary plate is installed on the surface of the insulating and heat-insulating layer of the punch, and the position of the upper auxiliary plate is opposite to the surface of the punch, and the upper auxiliary plate electrode is installed between the upper auxiliary plate and the insulating and heat-insulating layer of the punch, and the upper auxiliary plate and the upper auxiliary plate electrode are fastened to the punch by bolts or mechanical connections;

[0046] The lower auxiliary plate and the lower auxiliary plate electrode are installed on the surface of the insulating and heat-insulating layer of the die, and their positions correspond to the die surface. The lower auxiliary plate electrode is installed between the lower auxiliary plate and the insulating and heat-insulating layer of the die, and the lower auxiliary plate and the lower auxiliary plate electrode are fastened to the die by bolts or mechanical connection.

[0047] The left and right sides of the upper auxiliary plate electrode and the lower auxiliary plate electrode are respectively connected to the positive and negative poles of the upper and lower auxiliary plate power supplies to form a current loop;

[0048] The forming electrodes are clamped at both ends of the metal sheet to be formed and form a loop with the blank metal sheet.

[0049] The punch and die are fixedly connected to the upper and lower platforms of the hydraulic press through T-slots and clamping mechanisms, and the movement directions of the punch and die are ensured.

[0050] The upper auxiliary plate is a metal plate of approximately the same thickness as the convex mold surface, and the cross-section of the auxiliary plate is adjusted based on the mold surface shape to ensure that the cross-sectional area at each location is similar;

[0051] The lower auxiliary plate is a metal plate of approximately the same thickness as the concave mold surface, and the cross-section of the auxiliary plate is adjusted based on the shape of the mold surface to ensure that the cross-sectional area at each location is similar.

[0052] The insulating and heat-insulating layers on the punch, die and pressure ring can be ceramic sheets or asbestos gaskets with the same mold surface as the die that have been subjected to insulating and heat-insulating treatment on the surfaces of the punch and die.

[0053] A current-assisted blank and die coordinated temperature control forming device and a hot forming method, comprising the following steps:

[0054] Step 1: Use laser cutting, wire cutting or water jet cutting to cut the metal sheet into the shape and size to be processed. The forming size is larger than the mold cavity size to ensure the size requirements of the formed part. The extra size on both sides is used for forming electrode clamping and grinding the edges of the metal sheet to remove burrs and other defects.

[0055] Step 2: Apply insulation and heat-insulating coating to the surfaces of the punch, die, and blank holder. By adjusting the treatment parameters, the insulation and heat-insulating coating is evenly distributed and has similar thickness in each part to ensure the forming accuracy of the parts. The coating thickness is between 50µm and 300µm.

[0056] Step 3: Install the punch and die on the upper and lower platforms of the hydraulic press respectively, ensuring that the punch and die are aligned in their center positions, and fix them to the upper and lower platforms of the hydraulic press by tightening bolts so that the punch can achieve mold closing action as the upper platform of the hydraulic press moves;

[0057] Step 4: Install the blank holder on another vertically movable upper platform of the hydraulic press, between the punch and the die, and corresponding to the molding surfaces of the punch and the die;

[0058] Step 5: Install the upper auxiliary plate on the surface of the male mold insulation layer, its position corresponding to the male mold surface, and install the upper auxiliary plate electrode between the upper auxiliary plate and the male mold insulation layer. The left side of the electrode is connected to the positive pole of the upper auxiliary plate power supply, and the right side is connected to the negative pole of the upper auxiliary plate power supply. Ensure that the upper auxiliary plate power supply is turned off during installation;

[0059] Step 6: Install the lower auxiliary plate on the surface of the insulating and heat-insulating layer of the concave mold. Its position corresponds to the concave mold surface. Install the lower auxiliary plate electrode between the lower auxiliary plate and the insulating and heat-insulating layer of the concave mold. The left side of the electrode is connected to the positive pole of the lower auxiliary plate power supply, and the right side is connected to the negative pole of the lower auxiliary plate power supply. Ensure that the power supply of the upper auxiliary plate is turned off during installation.

[0060] Step 7: Install forming electrodes on both sides of the metal sheet blank. The left side of the forming electrode is connected to the positive pole of the forming power supply, and the right side of the forming electrode is connected to the negative pole of the forming power supply. Ensure that the forming power supply is turned off during installation. Then spray lubricant on the surface of the metal sheet blank and place it on the lower auxiliary plate according to the forming position.

[0061] Step 8: Turn on the power supply of the upper auxiliary plate, the forming power supply, and the lower auxiliary plate, and gradually increase the current of each power supply. The temperature distribution of the upper auxiliary plate, the metal sheet blank, and the lower auxiliary plate is regulated by the current. When the upper auxiliary plate, the metal sheet blank, and the lower auxiliary plate gradually heat up to 400°C to 800°C, they are kept at this temperature for 1 minute to 5 minutes.

[0062] Step 9: Start the hydraulic press, move the blank holder downward, and apply a blank holder force to the metal sheet to prevent the metal sheet from wrinkling or other instability during the forming process;

[0063] Step 10: The punch moves downward to press the metal sheet into a thin-walled part with the mold surface, so that the punch, upper auxiliary plate, metal sheet, lower auxiliary plate and die fit tightly together;

[0064] Step 11: Measure the temperature of the metal sheet after forming with a thermocouple, and adjust the temperature of the upper auxiliary plate, the metal sheet, and the lower auxiliary plate by adjusting the current of each power supply. After maintaining the temperature and pressure for 2 to 3 minutes, gradually reduce the current of each power supply until it reaches zero.

[0065] Step 12: Turn off the power switch, start the hydraulic press, lift the blank holder and punch, and take out the formed parts.

Claims

1. A current-assisted blank and die coordinated temperature control forming device, characterized in that: It includes a punch, a punch insulation layer, an upper auxiliary plate electrode, an upper auxiliary plate, an upper insulation layer of a blank holder, a blank holder, a lower insulation layer of a blank holder, a forming electrode, a lower auxiliary plate, a lower auxiliary plate electrode, a die insulation layer, a die and a temperature measuring thermocouple; The male mold and female mold molding surfaces are respectively provided with a male mold insulation and heat insulation layer and a female mold insulation and heat insulation layer; The lower end of the male mold insulation layer is provided with a pressure ring, the upper end of the pressure ring is provided with an upper pressure ring insulation layer, and the lower end is provided with a lower pressure ring insulation layer; The upper auxiliary plate is arranged at the lower end of the upper auxiliary plate electrode; The upper auxiliary plate is installed on the surface of the insulating and heat-insulating layer of the punch, and the position of the upper auxiliary plate is opposite to the surface of the punch, and the upper auxiliary plate electrode is installed between the upper auxiliary plate and the insulating and heat-insulating layer of the punch, and the upper auxiliary plate and the upper auxiliary plate electrode are fastened to the punch by bolts or mechanical connections; The lower auxiliary plate and the lower auxiliary plate electrode are installed on the surface of the insulating and heat-insulating layer of the die, and their positions correspond to the die surface. The lower auxiliary plate electrode is installed between the lower auxiliary plate and the insulating and heat-insulating layer of the die, and the lower auxiliary plate and the lower auxiliary plate electrode are fastened to the die by bolts or mechanical connection. The left and right sides of the upper auxiliary plate electrode and the lower auxiliary plate electrode are respectively connected to the positive and negative poles of the upper and lower auxiliary plate power supplies to form a current loop; The forming electrodes are clamped at both ends of the metal sheet to be formed and form a loop with the blank metal sheet; The punch and die are fixedly connected to the upper and lower platforms of the hydraulic press through T-slots and clamping mechanisms, and the movement directions of the punch and die are ensured.

2. The current-assisted blank and mold coordinated temperature control forming device according to claim 1, characterized in that: The upper auxiliary plate is a metal plate of approximately the same thickness as the convex mold surface, and the cross-section of the auxiliary plate is adjusted based on the mold surface shape to ensure that the cross-sectional area at each location is similar; The lower auxiliary plate is a metal plate of approximately the same thickness as the concave mold surface, and the cross-section of the auxiliary plate is adjusted based on the shape of the mold surface to ensure that the cross-sectional area at each location is similar.

3. The current-assisted blank and mold coordinated temperature control forming device according to claim 1, characterized in that: The insulating and heat-insulating layers on the punch, die and pressure ring can be ceramic sheets or asbestos gaskets with the same mold surface as the die, which have been subjected to insulating and heat-insulating treatment on the surfaces of the punch and die.

4. The hot forming method for the current-assisted blank and die coordinated temperature control forming device according to claim 1, characterized in that: The steps are as follows: Step 1: Use laser cutting, wire cutting or water jet cutting to cut the metal sheet into the shape and size to be processed. The forming size is larger than the mold cavity size to ensure the size requirements of the formed part. The extra size on both sides is used for forming electrode clamping and grinding the edges of the metal sheet to remove burrs and other defects. Step 2: Apply insulation and heat-insulating coating to the surfaces of the punch, die, and blank holder. By adjusting the treatment parameters, the insulation and heat-insulating coating is evenly distributed and has similar thickness in each part to ensure the forming accuracy of the parts. The coating thickness is between 50µm and 300µm. Step 3: Install the punch and die on the upper and lower platforms of the hydraulic press respectively, ensuring that the punch and die are aligned in their center positions, and fix them to the upper and lower platforms of the hydraulic press by tightening bolts so that the punch can achieve mold closing action as the upper platform of the hydraulic press moves; Step 4: Install the blank holder on another vertically movable upper platform of the hydraulic press, between the punch and the die, and corresponding to the molding surfaces of the punch and the die; Step 5: Install the upper auxiliary plate on the surface of the punch, its position corresponding to the convex mold surface, and install the upper auxiliary plate electrode between the upper auxiliary plate and the insulating layer of the punch. The left side of the electrode is connected to the positive pole of the upper auxiliary plate power supply, and the right side is connected to the negative pole of the upper auxiliary plate power supply. Ensure that the power supply of the upper auxiliary plate is turned off during installation; Step 6: Install the lower auxiliary plate on the die, with its position corresponding to the die surface, and install the lower auxiliary plate electrode between the lower auxiliary plate and the die insulation layer. The left side of the electrode is connected to the positive pole of the lower auxiliary plate power supply, and the right side is connected to the negative pole of the lower auxiliary plate power supply. Ensure that the power supply of the upper auxiliary plate is turned off during installation; Step 7: Install forming electrodes on both sides of the metal sheet blank. The left side of the forming electrode is connected to the positive pole of the forming power supply, and the right side of the forming electrode is connected to the negative pole of the forming power supply. Ensure that the forming power supply is turned off during installation. Then spray lubricant on the surface of the metal sheet blank and place it on the lower auxiliary plate according to the forming position. Step 8: Turn on the power supply of the upper auxiliary plate, the forming power supply, and the lower auxiliary plate, and gradually increase the current of each power supply. The temperature distribution of the upper auxiliary plate, the metal sheet blank, and the lower auxiliary plate is regulated by the current. When the upper auxiliary plate, the metal sheet blank, and the lower auxiliary plate gradually heat up to 400°C to 800°C, they are kept at this temperature for 1 minute to 5 minutes. Step 9: Start the hydraulic press, move the blank holder downward, and apply a blank holder force to the metal sheet to prevent the metal sheet from wrinkling or other instability during the forming process; Step 10: The punch moves downward to press the metal sheet into a thin-walled part with the mold surface, so that the punch, upper auxiliary plate, metal sheet, lower auxiliary plate and die fit tightly together; Step 11: Measure the temperature of the metal sheet after forming with a thermocouple, and adjust the temperature of the upper auxiliary plate, the metal sheet, and the lower auxiliary plate by adjusting the current of each power supply. After maintaining the temperature and pressure for 2 to 3 minutes, gradually reduce the current of each power supply until it reaches zero. Step 12: Turn off the power switch, start the hydraulic press, lift the blank holder and punch, and take out the formed parts.

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