Automobile plate stamping process

Abstract

The invention discloses an automobile plate stamping process. The automobile plate stamping process comprises the following steps that S1, materials are prepared and blanked; s2, mold design; s3, the blank is pretreated through a continuous annealing process; s4, the mold is preheated; and S5, multi-stage progressive forming is carried out. The blank is subjected to continuous annealing process pretreatment, the plasticity of the material can be improved, internal stress is reduced, the uniformity and forming performance of the material are improved, and therefore the cracking risk in the stamping process is reduced; a multi-stage progressive forming method is adopted to replace a traditional one-time stretching forming method, local deformation and stress concentration of materials can be reduced, and therefore the risk of cracking is reduced, the quality of final parts is improved, and the material utilization rate is increased; the mold used in each step is relatively simple, the overall mold design and manufacturing cost is low, and maintenance is easier.

Description

Technical Field

[0001] The invention relates to the field of stamping technology, and in particular to a stamping process for automobile panels. Background Art

[0002] The automotive sheet metal stamping process is a processing method that passes metal sheets through a die under the action of a press to cause plastic deformation or separation, thereby obtaining parts with a certain shape, size and performance. This process is widely used in the automotive manufacturing industry to manufacture body panels (such as doors, hoods, fenders, etc.) and other structural parts.

[0003] However, with the increasing requirements for vehicle lightweighting and cost control, the traditional one-time stretch forming stamping process faces the challenges of low material utilization, high mold cost and low finished product quality. For example, stretching the sheet to the final shape in one operation may cause over-stretching of the material in certain areas, resulting in high stress concentration areas and increasing the risk of cracking. Since a large deformation amount needs to be achieved at one time, more material waste may occur, especially when dealing with complex shapes. In order to achieve a large deformation at one time, the mold usually needs a more sturdy and complex design, which increases the cost and maintenance difficulty of the mold. If quality problems such as cracking or surface defects are encountered, the entire part may be scrapped, and starting over will waste time and resources. Therefore, it is of great significance to develop an automotive sheet metal stamping process that can improve material utilization, reduce mold costs and improve the quality of finished products. Summary of the invention

[0004] The present invention aims to solve the deficiencies of the prior art and provides a stamping process for automobile panels.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A stamping process for automobile plate parts comprises the following steps:

[0007] S1, material preparation and blanking;

[0008] S11. Material selection: Select appropriate metal sheets according to the design requirements of the parts;

[0009] S12. Surface treatment: Pre-treat the metal sheet, clean it to remove grease or other contaminants on the surface of the metal sheet, or apply a protective film to prevent scratches or corrosion;

[0010] S13, blanking: Use a shearing machine or a laser cutting machine to cut the large piece of metal sheet into blanks suitable for placing in the mold according to the required size;

[0011] S14, Inspection and Classification: After blanking is completed, the blanks are subjected to a preliminary quality inspection to ensure that there are no defects such as cracks and burrs, and then classified and stored according to specifications to prepare for the next operation;

[0012] S2. Mould design;

[0013] According to the shape and size requirements of the final part, a series of intermediate transition shapes are designed. Each transition shape is an independent forming step, starting from a simple shape and gradually approaching the final shape; the corresponding mold is designed for each transition shape, including the punch and die;

[0014] S3, the blank is pretreated by a continuous annealing process;

[0015] S4, preheating the mold;

[0016] S5, multi-stage progressive forming;

[0017] S51, placing the blank into the first set of molds for preliminary forming; after completion, taking out the plate and placing it into the next set of molds for further forming until the final shape is reached;

[0018] S52. Quality inspection: Carry out necessary quality inspection after each forming step to ensure that there are no defects. If defects are found, the mold or process parameters should be adjusted in time.

[0019] In particular, in S13, before blanking, the original size of the sheet metal is inverted according to its shape after stamping, and then the stamping size margin is calculated according to the drawing process, and a dotted line of the original size contour of the sheet metal is drawn on a whole piece of original metal sheet that has not been blanked, leaving one or two stamping size margins between the original sizes of two adjacent sheets.

[0020] In particular, S3 includes the following steps:

[0021] S31, preheating, sending the blank into a preheating furnace for preheating;

[0022] S32, heating, sending the preheated blank into a heating furnace to further heat it to an annealing temperature;

[0023] S33, heat preservation, after reaching the annealing temperature, keep it for a certain time to ensure that the whole blank is evenly heated and recrystallized;

[0024] S34, cooling, after the heat preservation is completed, the blank is gradually cooled down through the cooling section;

[0025] S35, post-processing, the blank is corrected by a flattening machine to restore the flatness of the blank, the quality of the annealed blank is checked to ensure that it meets the requirements of subsequent processing, and it is classified and stored according to specifications;

[0026] S36, quality inspection, conduct mechanical property test and metallographic analysis on the processed blank to verify whether the material has reached the expected performance indicators.

[0027] In particular, when designing the mold, dedicated software is used to simulate the tool path and stress distribution, guide the design and adjustment of the mold, and ensure the best forming effect.

[0028] In particular, in S51, after the blank is placed in the die, a positioning device is used to ensure that it is accurately in a predetermined position, and the press is started to move the punch downward, forcing the blank to undergo plastic deformation along the contour of the die to form a desired shape.

[0029] The beneficial effects of the present invention are as follows: the present invention performs a continuous annealing process pretreatment on the blank, which can improve the plasticity of the material, reduce internal stress, and improve the uniformity and forming performance of the material, thereby reducing the risk of cracking during the stamping process; by preheating the mold, the temperature difference between the preheated blank and the mold can be avoided, which may cause the blank to cool too quickly and increase the risk of cracking; preheating the mold can reduce the adhesion between the blank and the mold, which helps to improve the surface quality of the finished product; moderately preheating the mold can reduce the thermal shock caused by temperature differences, thereby extending the service life of the mold; by adopting a multi-stage progressive forming method instead of a traditional one-time stretching forming method, the local deformation and stress concentration of the material can be reduced, thereby reducing the risk of cracking, and improving the quality of the final part and improving the material utilization rate; the mold used in each step is relatively simple, the overall mold design and manufacturing cost is low, and it is easier to maintain. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with embodiments:

[0031] A stamping process for automobile plate parts comprises the following steps:

[0032] S1, material preparation and blanking;

[0033] S11. Material selection: Select appropriate metal sheets according to the design requirements of the parts; the selection of materials needs to consider the mechanical performance requirements, cost and processing characteristics of the final product.

[0034] S12. Surface treatment: Pre-treat the metal sheet, clean it to remove grease or other contaminants on the surface of the metal sheet, or apply a protective film to prevent scratches or corrosion;

[0035] S13, Blanking: Use a shearing machine or a laser cutting machine to cut a large piece of metal sheet into a blank suitable for being placed in the mold according to the required size; before blanking, invert the original size of the sheet according to the shape of the sheet after stamping, and then calculate the stamping size margin according to the deep drawing process, draw a dotted line of the original size outline of the sheet on a whole piece of original metal sheet that has not been blanked, and leave one or two stamping size margins between the original sizes of two adjacent sheets;

[0036] S14, Inspection and classification: After blanking is completed, the blanks are subjected to preliminary quality inspection to ensure that there are no defects such as cracks and burrs, and then classified and stored according to specifications to prepare for the next operation.

[0037] S2. Mould design;

[0038] According to the shape and size requirements of the final part, a series of intermediate transition shapes are designed. Each transition shape is an independent forming step, starting from a simple shape and gradually approaching the final shape. A corresponding mold is designed for each transition shape, including a punch and a die. When designing the mold, special software is used to simulate the tool path and stress distribution to guide the design and adjustment of the mold and ensure the best forming effect.

[0039] S3. The blank is pre-treated by continuous annealing process; continuous annealing can improve the plasticity of the material, reduce internal stress, improve the uniformity and formability of the material, thereby reducing the risk of cracking during the stamping process;

[0040] The following steps are involved:

[0041] S31, preheating, sending the blank into the preheating furnace for preheating; the preheating temperature is generally controlled between 300℃ and 500℃, the purpose is to gradually heat up the plate and reduce the internal stress caused by the temperature gradient;

[0042] S32, heating, sending the preheated blank into a heating furnace to further heat it to an annealing temperature; for different materials, the annealing temperature will be different, and the heating speed and holding time need to be set according to the specific material properties and production requirements;

[0043] S33, insulation: after reaching the annealing temperature, keep it for a certain period of time to ensure that the entire billet is evenly heated and recrystallized; the insulation time depends on the thickness of the sheet and the material properties, generally ranging from a few minutes to tens of minutes;

[0044] S34, cooling. After the insulation is completed, the blank is gradually cooled down through the cooling section. The cooling method can be air cooling, water cooling or spray cooling. The appropriate cooling rate is selected according to the required mechanical properties. Rapid cooling can obtain higher strength, while slow cooling helps to improve ductility.

[0045] S35, post-processing, the blank is corrected by a flattening machine to restore the flatness of the blank, the quality of the annealed blank is checked to ensure that it meets the requirements of subsequent processing, and it is classified and stored according to specifications;

[0046] S36, quality inspection, conduct mechanical property test and metallographic analysis on the processed blank to verify whether the material has reached the expected performance indicators.

[0047] S4. Preheat the mold; this can avoid the temperature difference between the preheated blank and the mold, which may cause the blank to cool too quickly and increase the risk of cracking; preheating the mold can reduce the adhesion between the blank and the mold, which helps to improve the surface quality of the finished product; moderately preheating the mold can reduce the thermal shock caused by temperature differences, thereby extending the service life of the mold.

[0048] S5. Multi-stage progressive forming: Multi-stage progressive forming is a technology that replaces the traditional single deep drawing process with a series of gradually deepening forming steps. This method can reduce local deformation and stress concentration of the material, thereby reducing the risk of cracking and improving the quality of the final part.

[0049] S51, placing the blank into the first set of dies for preliminary forming, after placing the blank into the dies, using a positioning device to ensure that it is accurately in a predetermined position, starting a press to move the punch downward, forcing the blank to undergo plastic deformation along the contour of the die to form a desired shape; after completion, taking out the plate, placing it into the next set of dies to continue forming until the final shape is reached;

[0050] S52. Quality inspection: Carry out necessary quality inspection after each forming step to ensure that there are no defects. If defects are found, the mold or process parameters should be adjusted in time.

[0051] The multi-stage progressive forming method has the following advantages compared to one-time stretch forming:

[0052] Reduce local deformation and stress concentration of materials: Through gradually deepening the forming steps, only a part of the deformation is performed each time, which can distribute stress more evenly, reduce local stress concentration, and reduce the possibility of cracking. Improve material utilization: Through multiple small-scale forming, the material flow can be better controlled, waste generation can be reduced, and material utilization can be improved. Improve surface quality and dimensional accuracy: Through step-by-step forming, the material flow can be better controlled, surface defects can be reduced, and the surface finish and dimensional accuracy of the finished product can be improved. Adapt to more complex geometric shapes: Through multi-step forming, complex geometric shapes can be gradually formed, which is suitable for a wider range of part designs, including those with deep cavities and complex surfaces. Reduce mold costs and maintenance costs: The molds used in each step are relatively simple, the overall mold design and manufacturing costs are low, and it is easier to maintain. Improve production efficiency and flexibility: Inspections can be carried out after each step of forming, and problems can be discovered and corrected in time, avoiding losses caused by major defects in the later stage. In addition, this process allows parameters to be adjusted between different steps, which improves production flexibility.

[0053] The above is an exemplary description of the present invention. Obviously, the specific implementation of the present invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the present invention, or they are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A stamping process for automobile panels, characterized in that: The following steps are involved: S1, material preparation and blanking; S11. Material selection: Select appropriate metal sheets according to the design requirements of the parts; S12. Surface treatment: Pre-treat the metal sheet, clean it to remove grease or other contaminants on the surface of the metal sheet, or apply a protective film to prevent scratches or corrosion; S13, blanking: Use a shearing machine or a laser cutting machine to cut the large piece of metal sheet into blanks suitable for placing in the mold according to the required size; S14, Inspection and Classification: After blanking is completed, the blanks are subjected to a preliminary quality inspection to ensure that there are no defects such as cracks and burrs, and then classified and stored according to specifications to prepare for the next operation; S2. Mould design; According to the shape and size requirements of the final part, a series of intermediate transition shapes are designed. Each transition shape is an independent forming step, starting from a simple shape and gradually approaching the final shape; the corresponding mold is designed for each transition shape, including the punch and die; S3, the blank is pretreated by a continuous annealing process; S4, preheating the mold; S5, multi-stage progressive forming; S51, placing the blank into the first set of molds for preliminary forming; after completion, taking out the plate and placing it into the next set of molds for further forming until the final shape is reached; S52. Quality inspection: Carry out necessary quality inspection after each forming step to ensure that there are no defects. If defects are found, the mold or process parameters should be adjusted in time.

2. The automobile sheet metal stamping process according to claim 1, characterized in that: In S13, before blanking, the original size of the plate is inverted according to its shape after stamping, and then the stamping size margin is calculated according to the drawing process. The original size outline dotted line of the plate is drawn on a whole piece of original metal plate that has not been blanked, and one or two stamping size margins are left between the original sizes of two adjacent plates.

3. The automobile sheet metal stamping process according to claim 1, characterized in that: S3 includes the following steps: S31, preheating, sending the blank into a preheating furnace for preheating; S32, heating, sending the preheated blank into a heating furnace to further heat it to an annealing temperature; S33, heat preservation, after reaching the annealing temperature, keep it for a certain time to ensure that the whole blank is evenly heated and recrystallized; S34, cooling, after the heat preservation is completed, the blank is gradually cooled down through the cooling section; S35, post-processing, the blank is corrected by a flattening machine to restore the flatness of the blank, the quality of the annealed blank is checked to ensure that it meets the requirements of subsequent processing, and it is classified and stored according to specifications; S36, quality inspection, conduct mechanical property test and metallographic analysis on the processed blank to verify whether the material has reached the expected performance indicators.

4. The automobile sheet metal stamping process according to claim 1, characterized in that: When designing the mold, special software is used to simulate the tool path and stress distribution to guide the design and adjustment of the mold and ensure the best forming effect.

5. The automobile sheet metal stamping process according to claim 1, characterized in that: In S51, after the blank is placed in the die, a positioning device is used to ensure that it is accurately in the predetermined position, and the press is started to move the punch downward, forcing the blank to undergo plastic deformation along the contour of the die to form the desired shape.