Explain what is rough datum, fine datum, and how to choose rough datum and fine datum
Release Time:
2022-09-13
In the first process of machining the workpiece, the unprocessed blank surface is used as the positioning reference, and this positioning surface is called the rough reference.
The choice of coarse datum is as follows:
1. If the position requirements between the machined surface and the unprocessed surface on the valve workpiece must be guaranteed first, the unprocessed surface should be used as the rough reference. If there are many surfaces that do not need to be processed on the workpiece, the surface that requires higher position accuracy with the processing surface should be used as the rough reference.
2. If it is necessary to ensure that the margin of an important surface of the workpiece is uniform, the surface should be selected as the rough reference.
3. The surface selected as the rough reference should be flat and free of defects such as pouring, riser or flash, so that the positioning is reliable.
4. Coarse datums can generally only be used once, especially the main positioning datums, which may cause large position errors.
What is a fine benchmark? What is the choice of fine benchmark?
Use the processed surface of the workpiece as the positioning reference and weigh the precision reference.
The choice of fine benchmark is as follows:
1. Use the process reference as the fine reference to realize "reference coincidence" to avoid the occurrence of reference misalignment errors.
2. When the workpiece can be more conveniently processed by a certain set of fine datum positioning on other surfaces, this set of fine datum positioning should be used in most processes as much as possible to achieve "unified datum", so as to reduce tooling design and manufacturing costs and improve productivity , to avoid benchmark conversion errors.
3. When the finishing or finishing process requires the allowance to be as small and uniform as possible, the machined surface itself should be selected as the fine reference, that is, the principle of "self-based reference" should be followed. The position accuracy between the machined surface and other surfaces is required to be guaranteed by the preceding process.
4. In order to obtain uniform machining allowance or high position accuracy, the principle of mutual reference and repeated machining can be followed.
Tel
ADD
No. 115, Shuangxi Road, Qingyang Economic and Technological Development Zone, Chizhou City, Anhui Province, China
We are committed to:
High, medium and low pressure ball valves, gate valves, globe valves, butterfly valves, steam traps, regulating valves, pressure reducing valves, hydraulic control valves, throttle valves, power station valves, emergency shut-off valves, and other products.
We are committed to:
High, medium and low pressure ball valves, gate valves, globe valves, butterfly valves, steam traps, regulating valves, pressure reducing valves, hydraulic control valves, throttle valves, power station valves, emergency shut-off valves, and other products.
Maintenance and transportation
Service Hotline：
13485660555
SAF Coolest v1.3 设置面板 ATISX-ZYPN-QDADE-AWA
无数据提示
Sorry，当前栏目暂无内容！
您可以查看其他栏目或返回 首页