What are the contents of process analysis of part drawing in Wuxi part NC machining?

In the NC process analysis, first of all, process analysis shall be carried out on the part drawing to analyze whether the structural manufacturability of each processing part of the part conforms to the characteristics of NC processing. The main contents include:

1. The dimension marking of part drawing shall comply with the convenience of programming

On the NC machining drawing, it is advisable to use the same datum to annotate the dimension or directly give the coordinate dimension. This marking method is not only convenient for programming, but also convenient for coordinating the setting and calculation of design basis, process basis, detection basis and programming zero point.

2. The geometric element conditions of part contour structure shall be sufficient

During programming, all geometric elements constituting the part contour shall be defined. When analyzing the part drawing, it is necessary to analyze whether the conditions of various geometric elements are sufficient. If not, the machined parts cannot be programmed or modeled.

3. Can the machining accuracy and dimensional tolerance required by the parts be guaranteed

Although the machining accuracy of NC machine tool is very high, for some special cases, such as the machining of thin-walled parts, due to the poor rigidity of thin-walled parts, the cutting force and elastic concession of thin-walled parts are very easy to produce the vibration of cutting surface, which makes it difficult to ensure the dimensional tolerance of thin-walled thickness and increase its surface roughness. According to practical experience, for thin-walled parts with large area, When the thickness is less than 3mm, this problem should be paid full attention to in the process.

4. Are the geometric types and dimensions of the internal and external contours of the part consistent

In NC programming, if the geometric types of inner contour and outer contour of parts are the same or similar, consider whether they can be programmed in the same program to reduce tool specifications and tool change times as much as possible, so as to reduce auxiliary time and improve machining efficiency. It should be noted that the diameter of the tool is often limited by the inner contour arc radius R.

5. Can larger diameter cutting tools be used in the process structure design of parts

Using a larger diameter milling cutter to process can reduce the times of tool walking and improve the rigidity system of the tool. Not only the machining efficiency is improved, but also the machining quality of the workpiece surface and bottom is improved accordingly.

6. The fillet radius of the groove bottom of the part milling surface or the fillet radius r at the intersection of the bottom plate and the edge plate should not be too large

Because the large diameter of the contact between the milling cutter and the milling plane D = d-2r, where D is the diameter of the milling cutter. When D is constant, Fillet radius R (as shown in the figure) (1) the larger the shown, the worse the milling ability of the end edge of the milling cutter, the lower the efficiency and the worse the manufacturability. When R is large to a certain extent, it must even be processed with a ball end milling cutter, which should be avoided. When D is large and R is small, the larger the area of the milling plane of the end edge of the milling cutter, the stronger the ability to process the plane, and of course, the better the milling manufacturability. Sometimes, the bottom of milling When the surface area is large and the bottom arc R is also large, two r different milling cutters can be used for cutting twice.

7. Principle of ensuring uniform benchmark

If a part is reinstalled on the other side of the milling surface after milling one side, due to the inconsistent datum, it is often difficult to connect the tool because of the reinstallation of the part, and the contour position and size on the positive and negative sides are inconsistent after machining. Therefore, try to use the appropriate holes of the part itself, or take the reference edge of the part contour or specially set the process holes (such as adding the process boss on the blank or setting the reference holes on the allowance to be removed in the subsequent process as the positioning reference to ensure the accuracy of the relative position after two clamping processes.

8. Consider the deformation of parts

When the parts are deformed in the process of NC milling, it will not only affect the machining quality of the parts, but also jump the knife sometimes. At this time, the machining process of milling should be considered, and the rough and finish machining should be separated as much as possible, or the method of symmetrical allowance removal should be adopted. Of course, it can also be solved by heat treatment.

Key words: Wuxi parts NC machining

Article source: http://www.wxqnkj.com/