With the development of today’s society, the sheet metal industry has grown rapidly and it is now involved in the sheet metal industry. For any metal lamella part, it has a specific process. In the so-called process, in order to understand sheet metal processing technology, it is first necessary to understand the selection of sheet metal materials.
Cold-rolled sheets (SHCC), galvanized sheets (SECC, SGCC), copper (CU) brass, beryllium copper, aluminum sheets (6061,6063, hard aluminum) and the like are commonly used metal sheet materials. , Aluminum profile, stainless steel (mirror surface, brushed surface, matte surface), product role, material choice, product use and cost should generally be considered.
- 1. Cold rolled sheet SPCC: Mainly used for electroplating and fired parts, low cost, easy to mold, material thickness ≤ 3.2mm.
- 2. Hot rolled sheet SHCC: Electroplating, painted parts, low cost material T ≧ 3.0mm. It is not easy to mold and is mainly used for flat parts.
- 3. Galvanized plate SECC, SGCC: SECC electrolytic plate material is divided into N and P substances, and N is mainly the material used for surface treatment, high cost, P paint is not a member.
- 4. Copper: Conductive material is mainly used, the surface treatment is nickel, chrome, or no treatment, and the cost is high.
- 5. Aluminum plate: Generally used for surface chromate (J11-A), oxidation (conductive oxidation, chemical oxidation), high cost, silver plating, nickel plating.
- 6. Aluminum profile: Materials with complex cross-sectional structures are widely used in various sublaces. Surface treatment with aluminum panel.
- 7. Stainless Steel: Mainly used at high cost without surface treatment.
To describe the technical process of a part, you must first know the various technical requirements of the part drawing; drawing reviews are the most important part of the part’s process flow.
- 1. Check if the drawing is complete.
- 2. The display relationship of the drawing, whether the label is clear and complete, and whether the dimensional unit is marked.Focus size for assembly relationships and assembly requirements.The difference between a new drawing and an old drawing.
- 6. Chart code conversion.
- 7. Draw problems and feedback.
- 8. Material
- 9. Quality and process requirements
- 10. Official release drawings shall be stamped in the Quality Control chapter.
The extended drawing is a plan view (2D) based on the part drawing (3D).
- 1. Extend convenient ways to save materials and usability
- 2. Reasonable clearance and margin selection, T = 2.0 or less gap 0.2, T = 2-3 clearance 0.5, edge edge with short side (door panel)
- 3. Reasonable consideration of reasonable size: Ultimately negative difference, half positive; Hole size: Finally occupy half of positive difference, negative difference.
- 4. Glitch direction
- 5. Draw squeeze, press rivets, punching point (pocket) and other position directions, cross-sections
- 6. Check material, thickness, thickness tolerances;Special angle, inner radius of bending angle (usually R = 0.5)
- 8. Error prone (similar asymmetry) prompt
- 9. Place a larger view
- 10. The logo is where spray protection is needed.
Sheet Metal Machining
The process flow may differ depending on the structure of the sheet metal parts, but the total amount should not exceed the following points.
1, Branking: There are various blanking methods, but the main ones are as follows.
- 1> Scissors: Scissors are used to cut simple strips of material. Mainly used for blank forming. Low cost and accuracy less than 0.2 However, only blanks or blocks without holes or corners can be processed.
- 2> Punch: After unfolding on the board, a punch is used to separate the flat parts of the part to form various shapes. The advantages are short working time, high efficiency, high precision, low cost and suitable for mass production. You need to design the mold.
- 3> NC blanking, NC blanking First, program the NC program. Drawings developed using programming software are written by NC number plotters as identifiable programs. According to these procedures, flat portions of various shapes can be punched out one by one on a flat plate, but the structure is influenced by the structure of the tool. The cost is low and the accuracy is 0.15.
- 4>Laser blanking: The shape of a flat plate is cut on a large flat plate by a laser cutting method. You need to write a laser program like CNC punching. This can be a flat piece of various complex shapes with a high cost and accuracy of 0.1.
- 5> Saw: Mainly used for aluminum, square tube, round tube, round rod, low cost and low precision.
2. Fitter: countersunk hole, tapping, reaming, drilling
The sinking angle of the rivet is generally 120 ° C, the sinking angle of the countersunk screw is 90 ° C, and the sinking angle of the bottom hole is 30 ° C.
3. Flange processing:
Also called drawing hole or flange processing hole, make a large hole in a small hole and tap it. Mainly use relatively thin metal plates to increase strength and number of turns to avoid slipping. Generally used for thin plate thickness, normal shallow hole flange, constant thickness, thickness 30-40%, the height will be 40-60% higher than the flange height. The maximum flange height is obtained with a 50% tightening. When the thickness of the plate is as thick as 2.0, 2.5, etc., the thickness of the plate can be directly hit.
General punching, punching, chamfering, punching, punching (protruding), punching and tearing, drawing, forming and other processing methods are used. Machining requires a corresponding mold to complete operations such as punching dies, convex pocket dies, tearing dies, suction dies, and molding dies. The operation focuses primarily on position and orientation.
5. Press rivets:
Press rivets nuts, screws, loosening, etc., rivets on sheet metal parts, pay attention to the direction to complete the operation through the hydraulic rivet machine or punch.
Bending is the folding of a 2D panel into a 3D part. The process requires a folding bed and a corresponding bending die, and there is also a bending order. The principle is that the first one does not prevent the next knife from folding.
The number of bends was calculated by calculating a groove width 6 times the thickness of T = 3.0 mm or less. For example, 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
Folding bed mold classification, straight knife, machete (80 ° C, 30 ° C)
When the aluminum plate is bent, there are cracks that can widen the width of the lower mold groove and increase the upper mold R (the cracks do not occur due to quenching).
Precautions when bending: I plan the surface and need thickness, quantity; II bending direction
Bending angle; IV bending size; VI appearance, chrome-plated parts shall not have wrinkles.
Relationship between bending and riveting: Under normal conditions, the rivets are first tightened and then bent, but when pressing after rivet tightening, it is necessary to bend and then press. Bending, riveting and rebending may be required.
Also called splicing, it is a manufacturing process and technique for joining metals and other thermoplastic materials (such as plastics) at high temperature or high pressure.
- A.Welding: Argon arc welding, CO2 welding, gas welding, manual welding
- B. Pressure welding: spot welding, butt welding, projection welding
- C. Brazing: Electrochromic welding, copper wire
2> Welding method:
- A.CO2 gas shield welding
- B. TIG welding
- C. Spot welding
- D. Robot welding
Under normal circumstances, CO2 gas shield welding is used for iron plate welding boring, argon arc welding stainless steel, and aluminum welding. Robot welding saves man-hours, improves work efficiency and weld quality, and reduces work strength.
3> smooth welding V (V)
spot welding (O), insert welding or groove welding (Π), crimping (χ), single-sided V-welding, blunt end (V), U-welding, blunt, J -Welding, blunt, backend welding, crushing
4> Arrow line and connector
5> Welding defects and precautions
Spot welding: Insufficient strength collides with each other and applies the weld area
CO2 welding: high production efficiency, low energy consumption, low cost, strong rust resistance
Argon Arc Welding: Shallow elution depth, slow welding speed, low efficiency, high production cost, defects of tungsten clamp, good welding quality, non-ferrous metals such as aluminum, copper, magnesium can be welded.
6> Cause of welding deformation:
Insufficient preparation before welding, it is necessary to increase the number of jigs
Welding equipment improves bad process
7> Welding deformation effect positive method:
- Flame effect method
- Vibration method
- Artificial aging