According to the continuous research and summary of sheet metal parts processing technology of Bangbao Hardware over the years, it is found that today's sheet metal processing technology is constantly changing the process flow due to the improvement of production equipment, but all changes are inseparable from it, there are always the following points worth our thinking and research:

First, the selection of materials
Sheet metal processing materials commonly used are cold rolled sheet (SPCC), hot rolled sheet (SHCC), galvanized sheet (SECC, SGCC), copper (CU) brass, red copper, beryllium copper, aluminum plate (6061, 6063, hard aluminum, etc.), aluminum profiles, stainless steel (mirror, drawing surface, fog surface), according to the different role of the product, the selection of materials, Generally, the use and cost of the product should be considered.
1. Cold rolled sheet SPCC, mainly used in electroplating and paint parts, low cost, easy to form, material thickness ≤3.2mm.
2. Hot rolled plate SHCC, material T≥3.0mm, also used electroplating, paint parts, low cost, but difficult to form, mainly used flat parts.
3. Galvanized sheet SECC, SGCC. SECC electrolytic plate N material, P material, N material is not mainly surface treatment, high cost, P material for spraying parts.
4. Copper; Mainly with conductive materials, its surface treatment is nickel plating, chromium plating, or no treatment, high cost.
5. Aluminum plate; General surface chromate (J11-A), oxidation (conductive oxidation, chemical oxidation), high cost, silver plating, nickel plating.
6. Lu: xingcai; Materials with complex cross section structure are widely used in various boxes. Surface treatment with aluminum plate.
7. Stainless steel; Mainly used without any surface treatment, high cost.

Two, drawing review
To write parts of the process flow, first of all to know the parts of the various technical requirements; Drawing audit is the most important part of the preparation of parts process flow.
1. Check that the drawing is complete.
2. The relation of drawing view, whether the annotation is clear and complete, and the dimension unit.
3. Assembly relations, assembly requirements for key dimensions.
4. The new version of the old map difference.
5. Translation of foreign drawings.
6. Table code conversion.
7. Drawing problem feedback and buried.
8. material
9. Quality requirements and process requirements
10. The official issued drawing shall be stamped with quality control seal.

Three, expand matters needing attention
An expansion drawing is a plan (2D) developed according to the parts drawing (3D).
1. To expand the way to close, to facilitate the saving of materials and processing
2. Reasonable selection of gap and edge wrapping method, T=2.0 gap 0.2, T=2-3 gap 0.5, edge wrapping method using long edge wrapping short edge (door panel)
3. Reasonable consideration of tolerance dimensions: negative difference go to the end, positive difference go half; Hole shape size: positive difference to the end, negative difference to half.
4. Burr direction
5. Extraction, riveting, tearing, punching convex point (bag), and other position direction, draw a section view
6. Check material, plate thickness, plate thickness tolerance
7. Special Angle, bending Angle radius (general R=0.5) to try to fold and expand
8. Error prone (similar asymmetry) should be highlighted
9. Enlargements should be added where the size is larger
10. The place to be sprayed shall be indicated

Four, sheet metal processing process
According to the differences in the structure of sheet metal parts, the process can be different, but generally not more than the following points.
1. Blanking: There are various blanking ways, mainly in the following ways
(1). Shearing machine: is the use of shearing machine shear strip simple materials, it is mainly for mold blanking forming preparation processing, low cost, accuracy is less than 0.2, but can only be processed without holes without cutting Angle strip or block.
(2). Punch: is the use of punch in one step or more steps in the plate will be parts of the plate after punching forming various shapes of materials, its advantage is the cost of short hours, high efficiency, high precision, low cost, suitable for mass production, but to design the mold.
(3). CNC CNC blanking, NC blanking first to write numerical control processing program, the use of programming software, will draw the expansion diagram written into NC number pull processing machine tools can identify the program, so that according to these programs step by step a knife on the flat plate cutting the shape of the plate, but its structure by the tool structure, low cost, accuracy at 0.15.
(4). Laser blanking, is the use of laser cutting, in the large plate will be cut out the structure of the plate shape, the same as NC blanking need to write laser program, it can be a variety of complex shape of the plate, the cost is high, the accuracy of 0.1.
(5). Sawing machine: mainly used under aluminum profile, square tube, drawing tube, round bar material, low cost, low precision.
1. Fitter: sinking, tapping, reaming, drilling
Countersunk hole Angle is generally 120℃, used for rivets, 90℃ for countersunk head screws, tapping inch bottom hole.
2. Flanging: Also called pumping hole, hole, is in a small hole on the smoke into a larger hole, tapping again, mainly with the thickness of thin sheet metal processing, increase the strength and the screw thread turns, avoid sliding tooth, commonly used in thickness is thin, its around the normal shallow flanging, basic did not change, the thickness of thin thickness is allowed in the 30-40%, The maximum flanging height can be obtained when the flanging height is 40-60% higher than the normal flanging height. When the plate thickness is larger, such as 2.0 and 2.5, the plate thickness can be tapped directly.
3. Press: is the use of mold forming processing working procedure, general processing of punching and cutting Angle, blanking, punching convex hull (convex point), salt tear, suction hole and forming processing, the processing needs to have the corresponding mold to finish operation, such as punching blanking die, convex BaoMo, tearing mode, pumping hole pattern, forming mould, etc., operating mainly pay attention to the position, direction.
4. Pressure riveting: pressure riveting in terms of the company, the main pressure riveting nuts, screws, loose, etc., it is through the hydraulic pressure riveting machine or punch to complete the operation, riveting to the sheet metal parts, and riveting way, need to pay attention to the direction.
5. Bending; Bending is folding 2D flat pieces into D parts. Its processing needs to have a folding bed and the corresponding bending mold to complete, it also has a certain bending order, its principle is to the next knife does not interfere with the first folding, will produce interference after folding.
L Bending number is T=3.0mm less than 6 times the plate thickness calculation slot width, such as: T=1.0, V= 6.0 F=1.8, T=1.2, V=8, F=2.2, T=1.5, V=10, F=2.7, T=2.0, V=12, F=4.0
L Folding bed mold classification, straight knife, curved knife (80℃, 30℃)
L Aluminum plate bending, cracks, can increase the width of the lower die groove and increase the upper die R (annealing can avoid cracks)
L Points for attention when bending: ⅰ drawing, thickness and quantity of plate required; ⅱ Bending direction
ⅲ Bending Angle; ⅳ Bending size; Vi Appearance, electroplated chrome materials are not allowed to have creases.
Bending and pressure riveting process relationship, under normal circumstances first after bending pressure, but there will be interference after material pressure riveting is about to fold first after pressure, and some need to bend - pressure riveting - bending and other processes.
6. Welding: welding definition: the atoms and molecules of the material to be welded form an integral whole from the lattice distance of Jingda
① Classification: a fusion welding: argon arc welding, CO2 welding, gas welding, manual welding
B Pressure welding: spot welding, butt welding, bump welding
C brazing: electrochrome welding, copper wire
Welding method: A CO2 gas shielded welding
B argon arc welding
C welding, etc
D Robot welding
The selection of welding mode is according to the actual requirements and material, generally SPEAKING, CO2 shielded welding is used for iron plate welding. Argon arc welding for stainless steel, aluminum plate welding, robot welding, can save time, improve work efficiency and welding quality, reduce work intensity.
③ Welding symbols: δ Angle welding, д, I-type welding, V-type welding, unilateral V-type welding (V) with blunt edge V-type welding (V), spot welding (O), plug welding or slot welding (∏), roll edge welding (χ), unilateral V-type welding with blunt edge (V), With blunt U-type welding, with blunt J-type welding, back cover welding, meet welding
(4) Arrow lines and joints
(5) Welding defect and its prevention
Spot welding: the strength is not enough to hit the convex point, imposed welding area
CO2 welding: high productivity, low energy consumption, low cost, strong rust resistance
Argon arc welding: depth of dissolution, slow dissolution speed, low efficiency, high production cost, tungsten clip defect, but has the advantage of good welding quality, can weld non-ferrous metals, such as aluminum, copper, magnesium and so on.
⑥ Welding deformation cause: insufficient preparation before welding, need to increase fixture
Welding fixture defective improvement process
Bad welding sequence
⑦ Welding deformation effect method: flame effect method
Method of vibration
Hammering method
Artificial time imitation
The continuous progress of equipment, so that the production process of modernization, production process is also in accordance with this law does not change, and the development of China's sheet metal industry is also constantly by this group of hardware business never abandon the engineering personnel continue to push forward!