When processing CNC machining centers, the reasonable selection of positioning marks determines the quality of parts. It has a great impact on ensuring the requirements of dimensional accuracy and mutual position accuracy of parts, as well as the layout of the processing sequence. between the surfaces of rooms, when using a luminaire to install a room, the choice of positioning data will also affect the complexity of the structure of the luminaire. This requires that the fixture can not only withstand significant cutting forces, but also meet positioning accuracy requirements. Therefore, the selection of the positioning reference frame is a very important process issue. So, how to choose positioning data when machining parts with a CNC machining center? Here is a brief introduction:
1. The selected data should ensure accurate positioning of the workpiece, facilitate loading and unloading of the workpiece, quickly complete the positioning and clamping of the workpiece, ensure reliable clamping, and have a simple fixing structure.
2. The calculation of the data selected by the CNC machining center and the dimensions of each processing part is simple, minimizing the calculation of the dimension chain, avoiding or reducing calculation links and calculation errors.
3. Ensure various processing precisions. When specifically determining part positioning data, the following principles should be followed:
1) The origin of the workpiece coordinate system, i.e. the “programmed zero point” and the workpiece positioning reference point do not necessarily have to coincide, but there must be a geometric relationship defined between the two. The main purpose of selecting the origin of the workpiece coordinate system is to facilitate programming and measurement. For parts with high requirements for dimensional accuracy, when determining the positioning data, it should be considered whether the coordinate origin of the CNC machining center can be accurately measured via the positioning data.
2) When processing the data and completing the processing of each station on the CNC machining center, the selection of positioning data should take into account the completion of as much processing content as possible. For this reason, it is necessary to consider a positioning method that facilitates the treatment of all surfaces. For example, for the box, it is best to use a positioning method with two pins on one side to make it easier for the tool to process other surfaces. .
3) Try to choose the design data of the part as the positioning data. This requires that during coarse machining it is necessary to determine what type of raw data is used to process each surface of the fine data, i.e. each positioning data used on the machining center CNC needs to be processed in the previous ordinary machine tool or other machine tools. so that it is easy to ensure that every part is processed. The precision relationship between machined surfaces.
4) When the positioning data of CNC machining center parts is difficult to coincide with the design data, the assembly drawings should be carefully analyzed to determine the design function of the design data of the part through calculation of the dimensional chain, the geometric tolerance. between positioning data and design data must be strictly specified to ensure processing accuracy.
5) When station processing, including design data, cannot be carried out simultaneously on the CNC machining center, the positioning data should coincide with the design data as much as possible. At the same time, it should also be considered that after using this reference positioning, the processing of all key precision parts can be completed in one clamping.
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