What are the general technical requirements of the workpiece in machining

2020-08-28

Machining is short for machining and refers to the process of removing materials by machining accurately. The main work of machining is to realize the fine processing of raw materials through machine tools. According to the different processing methods, machining is divided into manual processing and CNC processing. To this end, small make up forward jig xia published "machining, the regular technical requirements of the workpiece", for the reader's reference only.




preface




There are many kinds of workpiece in machining, and there are also many processing methods. Different kinds of workpiece have different processing methods and technical requirements. What are the following?




One, cutting parts processing requirements




1. The parts shall be inspected and accepted according to the processing procedure. Only after passing the previous procedure inspection, can the parts be transferred to the next procedure.




2. The processed parts are not allowed to have burrs.

3. The finished parts shall not be placed directly on the ground, and necessary support and protection measures shall be taken. The machining surface is not allowed to have the defects such as rust and erosion and knock, scratch which affect the performance, life or appearance.


4. Rolling finished surface, no peeling after rolling.


5. There should be no oxide scale on the surface of the parts after heat treatment in the final process. The mating surface and tooth surface after finishing should not be annealed

6. Defects such as black skin, knock, random buckle and burr are not allowed on the surface of processed threads.

Ii. Requirements for forging parts processing

1. The nozzle and riser of forging should be cut enough to ensure no shrinkage cavity and serious deflection of forging.

2. Forgings should be forged and formed on a forging press with sufficient capacity to ensure that the forging is fully forged inside.

3. Visible cracks, folds and other defects affecting the appearance of the forging are not allowed. Local defects can be removed, but the depth of cleaning shall not exceed 75% of the machining allowance. Defects on the forging surface shall be cleaned and smoothed.

4. White spots, internal cracks and residual shrinkage holes are not allowed in forgings.

Iii. Requirements for welding parts processing

1. The defects must be thoroughly cleared before welding, and the groove surface should be smooth and smooth without sharp corners.

2. Welding parts defect areas can be removed by shovel, grinding, carbon arc gouging, gas cutting or mechanical processing.

3. Dirt such as sand, oil, water and rust within 20mm around the welding area and groove must be thoroughly cleaned.

4. During the whole welding process, the temperature in the preheating zone shall not be lower than 350°C

5. Apply welding in a horizontal position as far as conditions permit.

6. During repair welding, the electrode should not do too much transverse oscillation.

7. In surface stacking welding, the overlap between welding passes shall not be less than 1/3 of the width of welding passes. Plump weld flesh, no burn, crack or obvious nodule on weld surface.

8. The weld is beautiful in appearance, without any defects such as bite, slag addition, blowhole, crack, splash, etc.; The welding wave is uniform.

Iv. Requirements for casting processing

1. Cold isolation, crack, shrinkage cavity and penetration defects and serious incomplete defects (such as undercasting, mechanical damage, etc.) are not allowed on the casting surface.

2. Castings shall be cleaned up without burrs or flaring, and the spout riser on the non-machining indication shall be cleaned up flush with the surface of the casting.

3. The characters and marks on the unmachined surface of the casting shall be clearly distinguishable, and the position and font shall meet the requirements of the drawing.

4. Roughness of casting unmachined surface, sand mold casting R, not greater than 50 m.

5. Casting should be cleared of riser, flying thorn, etc. The residual amount of sprue riser on the unmachined surface should be leveled and polished to meet the surface quality requirements.

6. Molding sand, core sand and core box on the casting shall be cleaned.


7. The inclined parts of the casting and the dimensional tolerance zone shall be arranged symmetrically along the inclined plane.

8. Molding sand, core sand, core bone, fleshy sand, sticky sand, etc. on the casting shall be shoveled and smoothed out and cleaned.

9. The wrong type and cast deviation of boss should be corrected to achieve smooth transition and ensure appearance quality.

10. The creases on the unmachined surface of the casting shall be less than 2mm in depth and the spacing shall be greater than 100mm.

11. The unmachined surface of machine castings shall be shot peening or roller treatment to meet the requirements of cleanliness SA21/2.

12. Castings must be water toughened

13. The casting surface should be smooth, and the gate, burr and sand should be cleaned.

14. Cold insulation, cracks, holes and other casting defects that are harmful to use shall not be allowed in the casting.




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