Large scale machining is divided into processing stages. The surfaces with high processing quality requirements are divided into processing stages, which can be effectively divided into three stages: rough processing, semi finish processing and finish processing. Mainly for processing quality; It is conducive to the rational use of equipment, the arrangement of heat treatment procedures, and the detection of blank defects. First processing datum: during the processing of parts, the surface used as the positioning datum should be processed first, so as to provide a precise datum for subsequent processing as soon as possible. It is called "benchmark first".
For large-scale machined parts such as box, bracket and connecting rod, the plane shall be machined first and then the hole shall be machined. In this way, the holes can be machined by plane positioning, the position accuracy of the plane and the holes is improved, and the machining of the holes on the plane is convenient. The finishing of main surfaces (such as grinding, honing, fine grinding rolling, etc.) should be carried out at the stage of the process route. The surface finish after processing should be above ra0.8um. Any slight collision will damage the surface. After finishing, it should be protected with flannelette. Hands or other objects are not allowed to directly contact the workpiece, so as to avoid damage to the finished surface due to transfer and installation between processes.
How to remove burrs in large-scale machining?
1. The traditional way of manual deburring is steel file, sandpaper and grinding head; The trimming knife gradually replaces these traditional methods, which is simple and convenient to use, does not require technical treatment, saves cost and is environmentally friendly.
2. Chemical deburring is the automatic and selective deburring of parts made of metal materials based on the principle of electrochemical reaction. It can be widely used for deburring of pump body, valve body, connecting rod, plunger needle valve couple and other parts made of different metal materials in pneumatic, hydraulic, construction machinery, nozzle oil pump, automobile, engine and other industries. It is applicable to internal burrs that are difficult to remove, parts after heat treatment and finished machining.
3. Electrolytic deburring is suitable for deburring hidden parts, cross holes or complex shaped parts, with high production efficiency. Deburring time generally only takes a few seconds to tens of seconds. This method is often used for deburring gears, splines, connecting rods, valve bodies and crankshaft oil passage orifices, as well as sharp corner rounding. The disadvantage is that the vicinity of the burr of the part is also affected by electrolysis, and the original luster of the surface will be lost, and even the dimensional accuracy will be affected.
