Sheet metal processing process
According to the difference in the sheet metal processing structure of sheet metal parts, the process flow can be different, but the total does not exceed the following points.
Blanking: There are various blanking methods, mainly the following methods
①. Shearing machine: It is a simple piece of material that is cut by a shearing machine. It is mainly prepared for the blanking of the mold. The cost is low and the accuracy is less than 0.2, but it can only process non-porous and non-cut corner strips or blocks. Gold processing.
②. Punching machine: It uses a punching machine to flatten the flat parts after unfolding the parts on the sheet in one or more steps to form various shapes of materials. Its advantages are short sheet metal processing that consumes man-hours, high efficiency, high precision, low cost, and large application Mass consumption, but to design the mold.
③. NC CNC blanking. When NC blanking, you must first write a CNC machining program, and use programming software to compile the developed drawing into a program that can be recognized by the NC digital drawing machine, and let it punch each step on the plate according to these programs. The shape of the flat plate, but its structure is due to the tool structure, the cost is low, the accuracy is 0.15.
④. Laser blanking is the application of laser cutting sheet metal. The structure and shape of the flat plate is cut out on the large flat plate. The same as NC blanking, a laser program needs to be written. It can be used to cut various flat plate pieces with high cost and accuracy. At 0.1.
⑤. Saw machine: mainly use aluminum profile, square tube, figure tube, round bar, etc., with low cost and low accuracy.
Fitter: countersinking, tapping, reaming, drilling
The countersinking angle is usually 120 ℃ for pulling rivets and 90 ℃ for countersunk head screws and tapping inch bottom holes.
2. Flanging: also known as pumping, flipping, which is to draw a slightly larger hole in a smaller base hole, and then tap, mainly using sheet metal with a thinner thickness to increase its strength and number of thread turns To prevent slipping, it is generally used for thinner plate thickness. The shallow hem around the hole is normal. There is no change in thickness at all. When the thickness is allowed to be 30-40% thinner, it can be 40% higher than the normal hem height. At a height of 60%, the maximum flanging height can be obtained by extruding 50% through sheet metal. When the thickness of the plate is large, such as 2.0, 2.5 and other plate thickness, you can directly tap.
3． Punching machine: It is a processing procedure that uses die forming. The ordinary punching machine has punching, cutting angle, blanking, punching convex bulge (bump), punching tearing, punching, forming and other processing methods, and its processing requirements have corresponding The mold is used to complete the operation, such as punching blanking die, convex hull die, tearing die, punching die, forming die, etc. The operation mainly pays attention to the position and directionality.
4． Pressing riveting: As far as our company is concerned, there are mainly pressing riveting nuts, screws, loosening, etc., which are completed by hydraulic presses or punches, riveting to sheet metal parts, and riveting. Method, pay attention to directionality.
5． Bending; Bending is the processing of 2D flat sheet metal into 3D parts. Its processing requirements include the completion of a folding bed and the corresponding bending die, and it also has a certain number of bending times. The criterion is the first folding without interference on the next knife, and the latter folding will occur.
l The number of bending bars is 6 times the thickness of the plate below T = 3.0mm to calculate the 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 = 112, F = 4.0
l Folding mold classification, straight knife, machete (80 ℃, 30 ℃) sheet metal
l When the aluminum plate is bent, there is a crack, which can increase the width of the lower die and increase the upper die R (annealing can prevent cracks)
l Attention when bending: Ⅰ drawing surface, request sheet thickness, quantity; Ⅱ bending direction
Ⅲ Bending angle; Ⅳ Bending size; Ⅵ Appearance, chrome plating parts are not allowed to have creases.
The relationship between bending and riveting process. Under normal conditions, the riveting is performed first, and then the bending, but there are some parts that will intervene after the riveting, and then the first bending and then pressing.
6. Welding: Welding definition: Atomic and molecular distances from Jingda lattice are integrated into the material being welded
① Classification: a Condensation welding: argon arc welding, CO2 welding, gas welding, manual welding sheet metal processing
b Pressure welding: spot welding, butt welding, bump welding
c Brazing: electric chrome welding, copper wire
② Welding method: a CO2 gas maintenance welding
b argon arc welding
c Spot welding, etc.
d Robot welding
The selection of welding methods is based on practical requirements and materials. Generally speaking, CO2 gas maintenance welding is used for iron plate welding; argon arc welding is used for stainless steel and aluminum plate welding. Robot welding can save labor and improve work efficiency And welding quality, reducing work intensity.
③ Welding symbols: Δ fillet welding, Д, I-type welding, V-type welding, single-sided V-type welding (V) with blunt V-type welding (V), spot welding (O), plug welding or slot welding (∏) , Crimp welding (χ), single-sided V-shaped welding with blunt edge (V), U-shaped welding with blunt, J-shaped welding with blunt, back-sealing welding, per-welding
④ Arrow wire and connector
⑤ Welding loss and its prevention
Spot welding: bumps are not strong enough to impose welding area
CO2 welding: high consumption rate, low energy consumption, low cost, strong rust resistance
TIG welding: shallow penetration, slow welding speed, low efficiency, high consumption cost, tungsten defect, but good welding quality, can weld non-ferrous metals such as aluminum, copper, magnesium, etc.
⑥ Reasons for welding deformation: lack of preparation before welding, need to increase the fixture
Welding fixture bad improvement process sheet metal processing
Bad welding times
正 Positive method of welding deformation: flame positive method