Selection of machining method selection principle
The formulation of machining process regulations is an important procedure document that must be implemented for large mechanical machining plants. In the process of customizing the machining process regulations of large mechanical machining plants, in addition to formulating the selection principle of positioning benchmarks, attention should also be paid to the selection of machining methods. , The structure and shape of precision mechanical parts are composed of basic geometric surfaces. Many different machining methods can be selected for the same surface, but different machining methods will greatly affect the machining quality, machining efficiency and Machining costs. Therefore, relevant machining method selection principles should be formulated in the machining process regulations, so as to better improve the efficiency and quality of precision mechanical parts machining, and at the same time, it can better reduce the machining cost.
- 1. Determine the machining method according to the technical requirements of the processed surface to ensure that the precision mechanical parts that meet the customer’s requirements are processed.
- 2. Determine the machining method according to the nature of the processed material.
- 3. Determine the machining method according to the machining type of mechanical machining, use special and efficient equipment for large batches, and use general-purpose equipment for single and small batches.
- 4. Determine the machining method according to the existing equipment and technical conditions of the enterprise.
The above are the selection principles of machining methods stipulated in the machining process regulations. Using these selection principles reasonably can improve efficiency, improve quality, and save costs in machining.
The machining process specification is one of the process documents that stipulate the machining process and operation methods of the parts. In the machining process specification, whether the positioning datum can be correctly selected is important for improving the efficiency of precision mechanical parts machining and rationally arranging the machining procedures. Very important influence. The positioning datum is divided into rough datum and fine datum. The unprocessed surface on the blank is used as the positioning datum. This kind of positioning datum is called the rough datum. Use the processed surface as a positioning datum, and this positioning datum becomes a fine datum. When selecting the positioning datum, the fine datum should be selected according to the machining requirements of the parts, and the machining process route is pushed forward, and finally it is decided which group of surfaces should be used as the rough datum to process the fine datum.
1. The selection principle of rough reference for machining process
- (1) The principle of the first process selection: the first process of machining a workpiece should use a rough reference. Whether the rough reference is selected correctly will not only affect the first machining process, but also the entire process of workpiece machining.
(2) The principle of reasonable allocation of machining allowance: Considering the uniform machining allowance of important surfaces of the workpiece, the important surface should be selected as the rough reference.
(3) The principle of easy clamping: In order to stabilize the positioning and clamping of the workpiece, the rough datum selected is required to be as smooth and clean as possible, and no forging flash, casting pouring riser cut marks or other defects are allowed, and sufficient The support area.
(4) The principle that rough benchmarks generally cannot be reused.
2. Selection principle of precision benchmark for machining process
- (1) Principle of datum coincidence: Choose the design datum of the processed surface of the workpiece as the fine datum as much as possible, so as to better avoid the positioning error caused by the datum misalignment.
- (2) The principle of unification of datums: As far as possible, choose the same set of fine datums to machine as many surfaces as possible on the workpiece to ensure the accuracy of the relative positions of each machined surface.
- (3) The principle of mutual reference: When the position accuracy requirements between the two machining surfaces on the workpiece are relatively high, the two machining surfaces can be used as a reference to each other for repeated machining.
- (4) Self-reference principle: Some finishing processes for machining the surface of a workpiece require a small and uniform machining allowance, which requires the machining surface itself as a precision reference for machining.
Link to this article:Machining Process Rules And Methods
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