Template machining process for high-speed stamping die

Abstract

The invention relates to the technical field of template processing of stamping dies, and particularly discloses a template processing technology for a high-speed stamping die, which comprises the following steps of: 1, preparing a base material; secondly, rough machining is conducted on the appearance; thirdly, hole series rough machining is conducted; 4, heat treatment; fifthly, the datum plane is subjected to semi-finish machining; sixthly, shape finish machining is carried out; seventhly, hole series finish machining is conducted; eighthly, the datum plane and the right angle are subjected to flat grinding and fine trimming; 9, carrying out constant-temperature standing and stress release; tenthly, water milling edge grabbing and right-angle precision upgrading are conducted; eleventhly, secondary constant-temperature standing and allowance confirmation are carried out; twelfthly, instant processing and temperature difference control are carried out; and thirteenth, quality detection. The precision and quality of the high-speed stamping die can be effectively improved, damage to the die is avoided, the service life of the die is prolonged, the production cost is reduced, the quality and reliability of products are improved, and the machining requirement is met.

Description

Technical Field

[0001] The present invention relates to the technical field of template processing for stamping dies, and particularly to a template processing technology for high-speed stamping dies. Background Art

[0002] In high-speed stamping dies for automotive part processing, the template is the skeleton support component of the high-speed stamping die. Although it does not directly participate in material stamping, the template is the core basic component that determines the accuracy, rigidity, and service life of the die. It provides a positioning reference for working parts (punch, die) and auxiliary parts (guide pillar, guide sleeve) through high-precision mounting surfaces and hole systems, ensuring the relative position stability of each component during high-speed stamping, thereby ensuring the stamping quality of automotive covering parts and structural parts, and avoiding die failure or part defects caused by vibration and eccentric load.

[0003] However, for the templates of current high-speed stamping dies, in the traditional processing process, there is insufficient precision control and incomplete stress release. Micro-deformation may occur due to temperature difference, affecting the final dimensional stability, resulting in a reduction in the processing precision and quality of the die, and increasing the risk of deformation and cracking of the die under long-term high-speed impact, reducing the service life of the die, increasing production costs, affecting the quality and reliability of products, and being unable to meet the processing requirements. Summary of the Invention

[0004] Aiming at the defects of the above-mentioned existing technologies, the present invention provides a template processing technology for high-speed stamping dies, which can effectively improve the precision and quality of high-speed stamping dies, avoid damage to the dies, extend the service life of the dies, reduce production costs, improve the quality and reliability of products, and meet the processing requirements.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A template processing technology for high-speed stamping dies, comprising the following steps:

[0007] The first step is to prepare the base material. Select a suitable die steel as the template base material, and level the template to ensure that its flatness error is within the specified range;

[0008] The second step is rough machining of the outer shape. Rough mill the selected template, mill six sides of the template, remove oxide skin and burrs, and leave a single-sided finishing allowance on the bottom surface, top surface, and side surfaces;

[0009] The third step is rough machining of the hole system. Rough machine various holes required on the template through a drilling machine, and the hole diameter is larger than the reserved finishing allowance;

[0010] The fourth step is heat treatment. Quench and temper the template after rough machining to eliminate internal stress;

[0011] Step 5, semi-finishing of the reference plane. Take the bottom surface of the heat-treated template as the reference, rough grind the top surface with a grinding machine, leaving a single-sided finishing allowance in the thickness direction, and rough grind the two side reference planes;

[0012] Step 6, finish machining of the outer shape. Position and finish machine the bottom surface and the two side reference planes of the template through a CNC milling machine, and finish mill the outer contour of the template;

[0013] Step 7, finish machining of the hole system. Perform finish machining using a jig boring machine, precisely control the diameter size and hole spacing size of the holes to ensure their accuracy;

[0014] Step 8, precision finishing of the reference plane and right angles by surface grinding. Use a high-precision surface grinding machine to precision finish the six surfaces of the template, with the right angle accuracy between adjacent surfaces reaching ±0.005 mm, and leaving a single-sided finishing allowance on each of the six surfaces for subsequent micro-adjustment;

[0015] Step 9, constant temperature stillness and stress release. Move the template into a precision laboratory with a constant temperature of 22 °C, and let it stand still for 10 hours to completely dissipate the residual heat from processing. After the material size is initially stable, continue to let it stand still for 20 hours to release the internal residual stress and avoid deformation caused by stress concentration during subsequent processing;

[0016] Step 10, water grinding of the edges and upgrading of the right angle accuracy. Take out the template after constant temperature stillness, and use the water grinding process to finely grind the edges of the four side faces of the template. Allowance control: leave a single-sided finishing allowance of 0.005 mm to prevent dimensional over-tolerance caused by excessive grinding. Accuracy improvement: the right angle accuracy is upgraded from ±0.005 mm to ±0.002 mm;

[0017] Step 11, secondary constant temperature stillness and allowance confirmation. After edge machining, put the template back into a constant temperature environment of 22 °C and let it stand still for 10 hours to eliminate the microthermal influence generated during the grinding process and ensure that the temperature during detection is consistent with the processing state;

[0018] Step 12, immediate machining and temperature difference control. After confirming that the allowance is qualified, send the template after secondary constant temperature stillness to the surface grinding workshop for continued processing within 30 minutes. During processing, keep the temperature of the machine tool and the environment at 22 °C ± 1 °C, and use constant temperature coolant to ensure that there is no temperature fluctuation interference during the grinding process to complete the final dimension setting;

[0019] Step 13, quality inspection. Use a coordinate measuring machine to comprehensively inspect the various dimensions and geometric tolerances of the template to ensure that all inspection items meet the design requirements.

[0020] Preferably, in the second step, leave a single-sided finishing allowance of 1.5 mm on the bottom and top surfaces, a single-sided allowance of 1 mm on the side surfaces, the flatness ≤ 0.1 mm, and the perpendicularity between adjacent surfaces ≤ 0.05 mm.

[0021] Preferably, in the third step, mounting grooves and weight-reducing holes are machined. Meanwhile, the hole series are drilled to be 2 mm smaller than the designed size, and the hole position accuracy is ±0.15 mm.

[0022] Preferably, in the fourth step, it is heated to the quenching temperature of 1020 °C, oil-cooled after heat preservation, and then tempered twice at 180 °C for 3 hours to eliminate internal stress.

[0023] Preferably, in the fifth step, the top surface is rough-ground by a grinding machine, with a unilateral finish-machining allowance of 0.5 mm left in the thickness direction, flatness ≤0.03 mm, surface roughness Ra ≤1.6 μm, and the two side reference surfaces are rough-ground, perpendicularity ≤0.02 mm / 100 mm.

[0024] Preferably, during the machining in the sixth step, the length / width dimension tolerance is ±0.01 mm, the chamfer radius is R5 - R10 mm, and the surface roughness Ra ≤1.6 μm; the mounting grooves and weight-reducing holes are machined to the final size: the depth tolerance of the mounting groove is ±0.01 mm, the diameter tolerance of the weight-reducing hole is ±0.02 mm, and the hole spacing accuracy is ±0.005 mm.

[0025] Preferably, in the seventh step, the diameter dimension tolerance of the hole is accurately controlled at the H6 level, the hole spacing dimension accuracy reaches ±0.005 mm, and the cylindricity error is controlled within 0.003 mm.

[0026] Preferably, in the eighth step, a unilateral finish-machining allowance of 0.02 mm is left on each of the six surfaces for subsequent fine adjustment.

[0027] Preferably, after the thirteenth step, there is also a fourteenth step of surface strengthening treatment. The guiding surface and mounting surface are nitrided to improve surface wear resistance; after treatment, it is finish-ground to Ra ≤0.4 μm to ensure that the original accuracy is not affected.

[0028] Preferably, after the fourteenth step, there is also a fifteenth step of cleaning and packaging. The processed template is thoroughly cleaned with a cleaning agent to remove impurities such as oil stains and metal chips on the surface. After cleaning, it is dried, and then anti-rust packaged, waiting for subsequent assembly into a complete stamping die.

[0029] The beneficial effects produced by the present invention are as follows: Through constant-temperature stillness and stress release, the template is still for 30 hours in stages in a constant-temperature environment of 22°C. First, it dissipates residual heat for 10 hours, and then releases internal stress for 20 hours, eliminating processing residual heat and heat treatment residual stress, avoiding stress deformation in subsequent processing, and stabilizing dimensional accuracy; Through water grinding and edge grasping and precision upgrading, the edges of the template are precisely ground by the water grinding process, leaving a margin of 0.005 mm on each side. The right-angle accuracy is improved from ±0.005 mm to ±0.002 mm. Low-temperature difference grinding controls thermal deformation, and a small amount of margin is left to prevent over-tolerance, achieving micron-level right-angle accuracy and ensuring the perpendicularity of die assembly; Through secondary constant-temperature stillness and margin confirmation, after edge grasping, it is still at 22°C for 10 hours, and the quality inspection confirms a margin of 0.005 mm on each side, eliminating the influence of grinding micro-heat, ensuring that the temperature of the template during detection is consistent with the processing state, and avoiding misjudgment of the margin; Through immediate processing and temperature difference control, it is transferred to a surface grinding workshop at 22°C ± 1°C for processing within 30 minutes, and a constant-temperature coolant is used to avoid temperature difference deformation caused by staying at room temperature. The whole process is kept at a constant temperature to ensure the final grinding accuracy and eliminate temperature fluctuation errors. This processing technology can effectively improve the accuracy and quality of high-speed stamping dies, avoid damage to the dies, extend the service life of the dies, reduce production costs, improve the quality and reliability of products, and meet the processing requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 : is a schematic flow chart of an embodiment of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] To more clearly elaborate the structural features, technical means, and the specific purposes and functions achieved by the present invention, the following further details the present invention in conjunction with the drawings and specific embodiments:

[0032] This embodiment: As Figure 1 shown, a template processing technology for high-speed stamping dies includes the following steps:

[0033] The first step is to prepare the base material. Select a suitable die steel as the template base material, and level the template to ensure that its flatness error is within the specified range;

[0034] The second step is rough machining of the outer shape. Rough mill the selected template, mill six sides of the template, remove oxide skin and burrs, leave a finishing margin of 1.5 mm on each side for the bottom and top surfaces, and a margin of 1 mm on each side for the side surfaces. The flatness ≤ 0.1 mm, and the perpendicularity between adjacent surfaces ≤ 0.05 mm;

[0035] The third step is rough machining of the hole system. Rough machine various holes required on the template through a drilling machine, machine installation grooves and weight reduction holes, and at the same time machine the hole system to be 2 mm smaller than the design size, with a hole position accuracy of ±0.15 mm;

[0036] Step 4, Heat treatment: Quench and temper the rough-machined template. Heat it to the quenching temperature of 1020°C, hold for a certain time and then cool it in oil. Subsequently, perform two temperings at 180°C for 3 hours to eliminate internal stress.

[0037] Step 5, Semi-finishing of the reference surface: Take the bottom surface of the heat-treated template as the reference, rough grind the top surface with a grinding machine, leaving a single-sided finishing allowance of 0.5 mm in the thickness direction. The flatness should be ≤0.03 mm, and the surface roughness Ra should be ≤1.6 μm. Rough grind the two side reference surfaces, and the perpendicularity should be ≤0.02 mm / 100 mm.

[0038] Step 6, Finish machining of the outer shape: Perform finish machining on the bottom surface and the two side reference surfaces of the template by positioning with a CNC milling machine. Precision mill the outer contour of the template, with the length / width dimension tolerance of ±0.01 mm, round the corners with R5 - R10 mm, and the surface roughness Ra should be ≤1.6 μm. Machine the installation slots and weight-reducing holes to the final dimensions: the depth tolerance of the installation slots is ±0.01 mm, the diameter tolerance of the weight-reducing holes is ±0.02 mm, and the hole spacing accuracy is ±0.005 mm.

[0039] Step 7, Finish machining of the hole system: Perform finish machining with a coordinate boring machine, precisely control the hole diameter dimension tolerance at H6 level, the hole spacing dimension accuracy reaches ±0.005 mm, and the cylindricity error is controlled within 0.003 mm to ensure its accuracy.

[0040] Step 8, Precision grinding and finishing of the reference surface and right angles: Use a high-precision surface grinding machine to precision grind the six surfaces of the template. The right angle accuracy between adjacent surfaces is up to ±0.005 mm, and a single-sided finishing allowance of 0.02 mm is left on each of the six surfaces for subsequent micro-adjustment.

[0041] Step 9, Constant-temperature stillness and stress release: Move the template into a precision laboratory with a constant temperature of 22°C and keep it still for 10 hours to completely dissipate the machining residual heat and initially stabilize the material dimensions. After that, continue to keep it still for 20 hours to release the internal residual stress and avoid deformation caused by stress concentration during subsequent machining. This solves the problems of stress deformation and temperature influence, eliminates the machining residual heat and stabilizes the dimensions. During machining, operations such as grinding and heat treatment will generate residual heat, causing slight expansion of the material or internal stress concentration. Keeping it still for 10 hours can completely dissipate the grinding heat and avoid dimensional measurement deviation caused by uneven temperature, such as the size shrinking beyond the tolerance after cooling although it is qualified under the thermal expansion state. At the same time, after heat treatment, there are residual stresses in the die steel. Continuing to keep it still for 20 hours (accumulatively 30 hours) can gradually release the internal stress through stress relaxation and avoid the micro-deformation caused by the sudden release of stress during subsequent precision machining, and avoid the deformation of the template caused by incomplete release of the heat treatment stress or un-dissipated machining residual heat, ensuring the stability of the reference surface during subsequent finish machining.

[0042] Step 10: Upgrade the water grinding of the edge gripping and right-angle precision. Take out the template after constant temperature and stillness. Adopt the water grinding process to finely grind the edge of the four sides of the template. Remaining allowance control: Leave a fine grinding allowance of 0.005 mm on each side to prevent dimensional deviation caused by excessive grinding. Precision improvement: The right-angle precision is improved from ±0.005 mm to ±0.002 mm. Use deionized water as the coolant to quickly remove the grinding heat. The temperature in the grinding area can be controlled within a fluctuation of ±2°C to avoid micro-expansion of the material caused by local high temperature. For example, a 10°C temperature rise may cause a linear expansion of 0.01 mm / m for steel, ensuring stable dimensions during edge gripping. And leave a fine grinding allowance of 0.005 mm on each side, only removing 5 μm of material. Through multiple micro-grindings, avoid excessive grinding caused by the grinding wheel pressure or machine tool vibration. The right-angle precision is improved from ±0.005 mm to ±0.002 mm to meet the precise fitting requirements of high-speed stamping dies. At the same time, control the transition radius of the edge during the edge gripping process to avoid stress concentration at sharp corners, and at the same time improve the surface roughness of the edge to reduce the friction loss during subsequent assembly, solving the problems of grinding thermal deformation and out-of-control dimensions in one-time grinding in traditional dry grinding / oil grinding. Achieve millimeter-level precision through low temperature difference and micro-machining, ensuring that the reference surface is absolutely perpendicular during die assembly.

[0043] Step 11: Secondary constant temperature and stillness and allowance confirmation. After the edge gripping process, put the template into a constant temperature environment of 22°C and still for 10 hours to eliminate the influence of the extremely small amount of heat generated during the grinding process, ensuring that the temperature during detection is the same as the processing state and completing the final dimensional shaping. Even though the water grinding has significantly cooled down, a very small amount of heat will still be generated during the grinding process. Standing for 10 hours can equalize the overall temperature of the template to 22°C, the ambient temperature, avoiding misjudgment of the allowance caused by local thermal expansion during detection. At the same time, the allowance detection of high-speed stamping dies relies on a coordinate measuring machine. Only by standing in a constant temperature environment for enough time can it be ensured that the detection state is equal to the processing state, avoiding systematic errors caused by inconsistent temperatures and misjudgment of the allowance caused by the temperature difference between the detection environment and the processing environment, ensuring the accuracy of the allowance for subsequent surface grinding. For example, if processed according to the detected value of 0.005 mm, actually only 0.003 mm needs to be removed due to thermal expansion, resulting in dimensional deviation, and completely eliminating over-processing or under-processing from the source.

[0044] The twelfth step is immediate processing and temperature difference control. After confirming that the allowance is qualified, send the template after the second constant temperature and stillness to the surface grinding workshop for continuous processing within 30 minutes. During processing, keep the temperature of the machine tool and the environment at 22°C ± 1°C, and use constant temperature coolant to ensure that there is no temperature fluctuation interference during the grinding process. Transfer it from the constant temperature laboratory to the surface grinding workshop within 30 minutes to avoid the linear expansion of the steel caused by staying in the normal temperature environment for more than 1 hour, which may damage the dimensional stability of the previous constant temperature treatment. Keep the temperature of the machine tool environment, coolant, and template consistent to eliminate local thermal deformation caused by machine tool heating and coolant temperature difference during the processing, and solve the interference of temperature fluctuation during the processing on high-precision grinding. Especially for the template thickness tolerance of high-speed stamping dies, it is usually ≤ ±0.005mm. Temperature difference control can prevent the millimeter-level precision from failing under the influence of temperature and ensure the stability of the die during high-speed stamping;

[0045] The thirteenth step is quality inspection. Use a coordinate measuring machine to comprehensively inspect the various dimensions and geometric tolerances of the template to ensure that all inspection items meet the design requirements.

[0046] The fourteenth step is surface strengthening treatment. Perform nitriding treatment on the guiding surface and installation surface to improve surface wear resistance; after treatment, finish grinding to Ra ≤ 0.4μm to ensure that the original accuracy is not affected.

[0047] The fifteenth step is cleaning and packaging. Use a cleaning agent to thoroughly clean the processed template to remove impurities such as oil stains and metal chips on the surface. After cleaning, perform a drying treatment, and then perform anti-rust packaging, waiting for subsequent assembly into a complete stamping die.

[0048] Through multiple constant temperature stillness and micro-grinding, this processing technology controls the right-angle accuracy, flatness, and hole spacing of the template at the sub-micron level, meeting the requirements of zero deviation of the die for high-speed stamping; by stress release and temperature difference control, it reduces the risk of deformation and cracking of the die under long-term high-speed impact, extending the service life; at the same time, it can reduce the number of die repairs, lower the rework cost. At the same time, high-precision processing reduces the grinding time during die assembly, effectively improving the accuracy and quality of high-speed stamping dies, enhancing the quality and reliability of products, and meeting the processing requirements.

[0049] It solves the three core problems of stress deformation, temperature drift, and grinding heat interference in traditional die processing, realizes the comprehensive improvement of die accuracy, life, and reliability, and meets the industry requirements of high precision, long life, and low maintenance for high-speed stamping dies.

[0050] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made to the above embodiments according to the technical solutions of the present invention still fall within the scope of the technical solutions of the present invention.

Claims

1. A template processing technology for high-speed stamping dies, characterized in that, It includes the following steps: The first step is to prepare the base material. Select a suitable die steel as the template base material, and level the template to ensure that the flatness error is within the specified range. The second step is rough machining of the outer shape. Rough mill the selected template, milling six sides of the template to remove the oxide skin and burrs, and leaving a single-sided finishing allowance on the bottom, top, and side surfaces. The third step is rough machining of the hole system. Rough machine various holes required on the template through a drill press, with the hole diameter larger than the reserved finishing allowance. The fourth step is heat treatment. Quench and temper the rough-machined template to eliminate internal stress. The fifth step is semi-finishing of the reference surface. Using the bottom surface of the heat-treated template as the reference, rough grind the top surface with a grinding machine, leaving a single-sided fine grinding allowance in the thickness direction, and rough grind the two side reference surfaces. The sixth step is finish machining of the outer shape. Finish machine the bottom surface and the two side reference surfaces of the template through a CNC milling machine to precisely mill the outer contour of the template. The seventh step is finish machining of the hole system. Use a coordinate boring machine for finish machining to precisely control the hole diameter size and hole spacing size to ensure its accuracy. The eighth step is precision grinding and straightening of the reference surface and right angle. Use a high-precision surface grinding machine to precision grind the six surfaces of the template, with the right angle accuracy between adjacent surfaces reaching ±0.005 mm, and leaving a single-sided fine grinding allowance on each of the six surfaces for subsequent micro-adjustment. The ninth step is constant temperature stillness and stress release. Move the template into a precision laboratory with a constant temperature of 22 °C and keep it still for 10 hours to completely dissipate the processing heat. After the material size is initially stable, continue to keep it still for 20 hours to release the internal residual stress and avoid deformation caused by stress concentration during subsequent processing. The tenth step is water grinding of the edge and upgrading of the right angle accuracy. Take out the template after constant temperature stillness, and use the water grinding process to finely grind the edges of the four side surfaces of the template. Allowance control: Reserve a single-sided fine grinding allowance of 0.005 mm to prevent over-grinding from causing dimensional out-of-tolerance. Accuracy improvement: The right angle accuracy is improved from ±0.005 mm to ±0.002 mm. The eleventh step is secondary constant temperature stillness and allowance confirmation. After edge machining, put the template back into a 22 °C constant temperature environment and keep it still for 10 hours to eliminate the microthermal influence generated during the grinding process and ensure that the temperature during detection is consistent with the processing state. The twelfth step is immediate machining and temperature difference control. After confirming that the allowance is qualified, send the template after secondary constant temperature stillness to the surface grinding workshop for continued processing within 30 minutes. Keep the temperature of the machine tool and the environment at 22 °C ± 1 °C during processing, and use a constant temperature coolant to ensure that there is no temperature fluctuation interference during the grinding process to complete the final dimension setting. The thirteenth step is quality inspection. Use a coordinate measuring instrument to comprehensively inspect the various dimensions and geometric tolerances of the template to ensure that all inspection items meet the design requirements.

2. The template processing technology for high-speed stamping dies according to claim 1, characterized in that: In the second step, leave a single-sided finishing allowance of 1.5 mm on the bottom and top surfaces, a single-sided allowance of 1 mm on the side surfaces, the flatness ≤ 0.1 mm, and the perpendicularity between adjacent surfaces ≤ 0.05 mm.

3. The template processing technology for high-speed stamping dies according to claim 1, characterized in that: In the third step, machine the installation grooves and weight-reducing holes, and at the same time machine the hole system by drilling to a size 2 mm smaller than the design size, with the hole position accuracy of ±0.15 mm.

4. The template processing technology for high-speed stamping dies according to claim 1, wherein: In the fourth step, heat to the quenching temperature of 1020 °C, cool in oil after holding the temperature, and then temper twice at 180 °C for 3 hours to eliminate internal stress.

5. The template processing technology for high-speed stamping dies according to claim 1, characterized in that: In the fifth step, the top surface of the grinding machine is rough ground, with a single-sided finish grinding allowance of 0.5 mm left in the thickness direction, flatness ≤ 0.03 mm, surface roughness Ra ≤ 1.6 μm, and the two side reference surfaces are rough ground, perpendicularity ≤ 0.02 mm / 100 mm.

6. The template processing technology for high-speed stamping dies according to claim 1, characterized in that: During the processing of the sixth step, the length / width dimension tolerance is ±0.01 mm, the chamfer radius is R5-R10 mm, and the surface roughness Ra ≤ 1.6 μm; the installation groove and the weight-reducing hole are machined to the final dimensions: the depth tolerance of the installation groove is ±0.01 mm, the diameter tolerance of the weight-reducing hole is ±0.02 mm, and the hole pitch accuracy is ±0.005 mm.

7. The template processing technology for high-speed stamping dies according to claim 1, characterized in that: In the seventh step, the diameter dimension tolerance of the hole is accurately controlled at the H6 level, the hole pitch dimension accuracy reaches ±0.005 mm, and the cylindricity error is controlled within 0.003 mm.

8. The template processing technology for high-speed stamping dies according to claim 1, characterized in that: In the eighth step, a single-sided finish grinding allowance of 0.02 mm is left on each of the six sides for subsequent fine adjustment.

9. The template processing technology for high-speed stamping dies according to claim 1, characterized in that: After the thirteenth step, there is also a fourteenth step of surface strengthening treatment. The guide surface and the installation surface are nitrided to improve surface wear resistance; after treatment, it is finish ground to Ra ≤ 0.4 μm to ensure that the original accuracy is not affected.

10. The template processing technology for high-speed stamping dies according to claim 1, characterized in that: After the fourteenth step, there is also a fifteenth step of cleaning and packaging. The processed template is thoroughly cleaned with a cleaning agent to remove impurities such as oil stains and metal chips on the surface. After cleaning, it is dried, and then anti-rust packaged, waiting to be assembled into a complete stamping die subsequently.

Images