Sheet Metal Fabrication Process

According to the structure difference of stamped sheet metal parts, the technological process may be different, but the total does not exceed the following points.
 
1. Cutting: There are various ways of cutting, mainly the following ways
 
2. Shearing machine: The shearing machine is used to cut simple strip parts. It is mainly used to prepare for blanking forming of the die. The cost is low and the precision is less than 0.2, but it can only process strip or block without a hole and cut angle.
 
3. Punch: It is to use the punch to punch sheet metal fabrication parts into various shapes in one or more steps. Its advantages are short time consuming, high efficiency, high accuracy, low cost, suitable for mass production, but die design is needed.
 
4. NC cutting, NC cutting first to write NC programming, using programming software, will draw the development diagram into NC numerical broaching machine tool recognizable program, so that according to these programs one by one, stamping flat parts of various structural shapes on the plate, but its structure is affected by the structure of the tool, low cost, accuracy is less than 0.1.
 
5. Laser blanking is the use of a laser cutting method to cut out the structural shape of its flat plate on a large flat plate. Like NC blanking, it needs to write a laser program. It can lay various complex-shaped flat plates with high cost and accuracy of 0.1.
 
Sawing Machine: Mainly used for aluminum profiles, square pipes, circular pipes, round bars, and other materials, low cost, low precision.
 
1. Fixters: sinking, tapping, reaming, drilling
The sinking angle is generally 120 for rivet pulling, 90 for countersunk head screw, and the bottom hole is made in English by tapping.
 
2. Flanging: also known as punching, flanging, is to draw a slightly larger hole on a smaller base hole, and then tap, mainly using sheet metal processing with thinner plate thickness, increasing its strength and number of threaded rings, avoiding slippery teeth, generally used for shallow flanging with thinner plate thickness and normal hole periphery. The thickness is unchanged. When the thickness is reduced by 30-40%, 40-60% higher than the normal flanging height can be obtained. When the thickness is reduced by 50%, the maximum flanging height can be obtained. When the thickness is larger, such as 2.0, 2.5 or more, the flanging height can be directly tapped.
 
3. Punching machine: It is a process of forming with dies. Generally, punching machine processes punching, cutting angle, blanking, punching convex hull (bump), punching tearing, punching, forming and other processing methods. Its processing needs corresponding dies to complete the operation, such as punching blanking die, punching hull die, tearing die, punching die, forming die, etc. Major attention should be paid to location and orientation.
 
4. Riveting: As far as the company is concerned, riveting mainly includes riveting nuts, bolts, looseness, etc. It is through hydraulic riveting machine or punch to complete the operation, riveting it to sheet metal parts, and riveting way, attention should be paid to the direction.
 
5. Bending: cnc metal bending is the process of turning a 2D flat piece into a 3D part. Its processing needs a bending machine and corresponding bending die to complete, it also has a certain bending order, its principle is that the next knife does not interfere with the first bending, will interfere with the back bending.
 
L The number of bending bars is 6 times the width of calculation slot of plate thickness below T=3.0mm, such as T=1.0, V=6.0F=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.
Classification of Folding Machine Moulds, Straight Knives and Bending Knives (80, 30)
 
When bending aluminum sheet, there are cracks, which can increase the width of lower die groove and increase the upper die R (annealing can avoid cracks)
 
Notes in bending: drawing, thickness, and quantity of sheets required; bending direction
Bending angle; Bending size; Appearance, chromium plating parts are not allowed to have creases.
 
The relationship between bending and the riveting process is that riveting is first pressed and then bending in general, but the interference of material parts after riveting requires first bending and then pressing, and some processes such as bending, riveting and bending are needed.
 
6. Welding: Welding Definition: The distance between atom and molecule of the welded material and Jingda lattice form a whole.
 
Classification: a Melting Welding: Argon Arc Welding, CO2 Welding, Gas Welding, Manual Welding
 
B pressure welding: spot welding, butt welding, impact welding
 
C brazing: electrochromium welding, copper wire
 
Welding mode: CO2 gas shielded welding
 
B argon arc welding
 
C spot welding, etc.
 
D Robot Welding
 
The selection of the welding method is based on the actual requirements and material quality. Generally speaking, CO2 gas shielded welding is used for iron plate welding; Argon arc welding is used for stainless steel and aluminum plate welding. Robot welding can save time, improve work efficiency and welding quality, and reduce work intensity.
 
Welding symbols: △fillet welding, Д, I welding, V-type welding, single-side V-type welding (V) with blunt edge V-type welding (V), spot welding (O), plug welding or slot welding (), curling welding (), single-side V-type welding with blunt edge (V), U-type welding with blunt edge, J-type welding with blunt edge, bottom sealing welding, and joint welding.
 
Arrow line and junction
 
Welding Deficiency and Its Preventive Measures
 
Spot welding: not strong enough to punch, impose welding area
 
CO2 welding: high productivity, low energy consumption, low cost, strong rust resistance
 
Argon arc welding: shallow dissolution depth, slow dissolution speed, low efficiency, high production cost, with tungsten inclusion defects, but with good welding quality advantages, can weld non-ferrous metals, such as aluminum, copper, magnesium and so on.
 
Welding Deformation Reasons: Insufficient Preparations before Welding, Need to Increase Fixtures
 
Improving technology of welding fixture
 
Poor welding sequence
 
Welding Deformation Correction Method: Flame Correction Method
 
Vibration method
 
Hammer
 
Artificial aging