technical details to be paid attention to in sheet metal processing

sheet metal processing is a basic and important process in manufacturing industry, which is widely used in electronic and electrical appliances, communication equipment, automobile manufacturing, aerospace and other fields. To ensure the quality and dimensional accuracy of sheet metal parts, it is essential to rigorously control all technical parameters throughout the manufacturing process. The following are the key technical points that require attention in sheet metal fabrication.

1. material selection and pretreatment

1. Material selection: Select the appropriate sheet metal material according to the product use. Common ones are cold-rolled steel plate, stainless steel, aluminum alloy, copper alloy, etc. The mechanical properties, corrosion resistance and processing characteristics of different materials are significantly different.

2. material thickness: the thickness directly affects the processing difficulty and product strength, and is generally controlled within the range of 0.5-6mm. Too thin and easy to deformation, too thick to increase the difficulty of processing.

3. Pretreatment requirements: The surface of the material shall be free of rust, oil and visible scratches. If necessary, perform pretreatment such as degreasing, rust removal and passivation to ensure the quality of subsequent processing.

4. Material texture direction: For textured materials, the effect of texture direction on bending performance should be considered to avoid cracking due to improper texture direction.

2. design specifications and process planning

1. Design rationality: the design of sheet metal parts should meet the requirements of processing technology, so as to avoid processing difficulties or cost increase caused by too complex structure.

2. Bending radius: The minimum bending radius should be greater than 0.5-1 times the thickness of the material to prevent cracking at the bend. Different materials have different minimum bend radius requirements.

3. Hole margin control: The distance from the hole edge to the bending line should be greater than 1.5 times the material thickness to avoid hole deformation during bending.

4. process route planning: reasonably arrange the process sequence of blanking, punching, bending, welding, etc. to avoid the subsequent process affecting the processing accuracy of the previous process.

3. blanking process control

1. Laser cutting: pay attention to the focus position, gas pressure, cutting speed and other parameter settings to ensure the quality of the cut. Stainless steel cutting requires nitrogen protection.

2. CNC punching machine: reasonable selection of molds to avoid deformation caused by using too large molds for small holes. Pay attention to the material positioning accuracy during continuous stamping.

3. Cut blanking: Control the shear gap (usually 5-8% of the material thickness) to ensure that the cut is smooth and free of burrs.

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4. Bending Technology

1. bending sequence: follow the principle of "first inside, then outside, first small, then large" to avoid interference. Complex parts need to make bending process cards.

2. Springback control: Different materials have different springback amounts, which need to be compensated by over-bending. Aluminum alloy springback is about 2-5 °, stainless steel up to 8-15 °.

3. mold selection: select the appropriate V-groove width of the lower mold according to the thickness of the material, generally 6-8 times the thickness of the material.

4. Bending force calculation: reasonably estimate the pressure required for bending to avoid inaccurate angle caused by equipment overload or insufficient pressure.

5. Protective measures: Use protective film or special tooling for bending vulnerable parts to prevent surface scratches.

Key points of 5. welding process

1. Welding method selection: According to the material thickness and joint form to choose spot welding, argon arc welding, laser welding and other appropriate methods.

2. Welding deformation control: use symmetrical welding, segmented welding, pre-deformation and other methods to reduce deformation, and use tooling fixtures when necessary.

3. Welding parameters: strictly control parameters such as current, voltage and welding speed to avoid burning through or incomplete fusion.

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6. finish techniques

1. pre-treatment: including oil removal, rust removal, phosphating, etc., to ensure surface cleanliness and adhesion.

2. spraying process: control the spraying distance (15-25cm), moving speed, overlapping rate and other parameters to ensure uniform coating.

3. electroplating treatment: pay attention to current density, temperature, time and other parameters, different metal electroplating process requirements are different.

4. Anodizing: mainly used for aluminum alloys to control electrolyte concentration, temperature, current density and time.

7. Quality Inspection and Control

1. dimension detection: use caliper, height gauge, three-coordinate and other tools to detect key dimensions, and the tolerance is generally controlled within ± 0.1mm.

2. Form and position tolerance: check flatness, perpendicularity, coaxiality, etc. Complex surfaces can be tested with templates.

3. Surface quality: visually inspect the surface for defects such as scratches, dents, oxidation, etc., and use a roughness meter if necessary.

4. functional test: assembly test to verify the fit size, salt spray test, hardness test and other special tests if necessary.

8. Safety Production Specification

1. Equipment safety: regularly check the safety devices of punching machines, bending machines and other equipment to ensure that the emergency stop function is normal.

2. Personal protection: the operator should wear protective glasses, gloves, etc., and the laser cutting area should wear special protective glasses.

3. Material handling: Pay attention to edge protection when handling large-size sheet metal parts to prevent cutting.

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9. common problems and solutions

1. Bending cracks: Check if the material is suitable for bending, increase the bending radius or anneal.

2. Dimensional deviation: calibrate the mold and equipment and check that the material is positioned correctly.

3. Surface scratches: Check the cleanliness of the mold and work surface, using protective film if necessary.

4. Welding distortion: optimize welding sequence, add rigid fixation or correction after welding.

By strictly controlling the above technical details, the quality and efficiency of sheet metal processing can be significantly improved, the scrap rate can be reduced, and the diversified needs of different industries for sheet metal parts can be met. With the development of intelligent manufacturing technology, digital and automated sheet metal processing technology will become the future development direction.