Chen min
(Fujian Sanming Vocational and Technical College, Sanming 365000)
Numerical control manufacturing technology is gradually being widely used. Process analysis is very important before part programming.
Function. Through the analysis of typical shaft parts NC machining process, the method of NC machining process analysis for general parts is given.
It has certain guiding significance for improving manufacturing quality and actual production.
Keywords: NC machining process design of shaft parts 1 Introduction
Process analysis is the preliminary process preparation of NC machining programming, no matter
Both manual programming and automatic programming need to be processed before programming.
Process analysis of parts. If the process analysis is not well considered, it will often lead to
Unreasonable process design leads to repeated programming work and doubled workload.
In addition, sometimes there will be a phenomenon of reinventing the wheel, causing some unnecessary losses.
Loss, in serious cases, even cause CNC machining errors. So it is comprehensive and reasonable.
The process analysis of NC programming is an important foundation and guarantee.
2 process analysis points
Generally, besides the conventional analysis of materials, shapes, dimensions and parts accuracy.
Degree, surface roughness and blank shape, heat treatment requirements, but also according to the number.
To control the machining characteristics of programming, pay attention to the following points.
2. 1 Marking of pattern size and determination of contour parameters
When reviewing and analyzing parts drawings, we should pay special attention to reasonable size standards.
Pay attention to the selection of programming origin, and the geometric conditions of part contour parameters must be
It must be enough.
In general, when dimensioning parts, designers need to do more tests.
Considering the use factors such as assembly, local scattered dimensioners are often used.
Method, which will bring some inconvenience to the process arrangement and numerical control processing, by
CNC machining accuracy and repetitive positioning accuracy are both high, and not very large.
The cumulative error of affects the performance. Therefore, it is recommended to divide it into local sizes.
Replace the scattered standard with the same benchmark or directly mark the coordinate size.
According to the characteristics of NC machining programming, the drawing of parts should be based on the same benchmark.
Marking dimensions by marking lines or directly marking coordinate dimensions is not only convenient for programming but also beneficial.
In the coordination of dimensions, we strive to achieve design benchmarks, process benchmarks and measurement benchmarks.
The datum is consistent with the programming origin (or programming datum).
The programming origin is correct as the starting point and ending point of programming coordinates.
Selection directly affects the machining accuracy of parts and the difficulty of coordinate point calculation.
When selecting the programming origin, the following principles should be paid attention to:
(1) The programming origin matches the dimension datum (design datum sum) best.
Process benchmark) coincidence;
(2) The selection of programming origin should be beneficial to programming and numerical calculation;
(3) The machining error caused by the programming origin should be minimum;
(4) The programming origin should be easy to find and convenient to measure the position.
2.2 Process analysis of parts structure
Machining circular arc and straight line or the connection between circular arc and circular arc on CNC lathe.
Internal and external contour, should fully consider the size of the transition arc radius, because the knife
The radius of the cutter head may lead to overcutting or undercut.
If this situation is found, you can use the method of automatic compensation of tool tip radius.
To solve; Cutting point and cutting point of cutter when machining internal and external contours with milling cutter.
It should be selected at the intersection of geometric parameters of the part outline, and the appropriate tangent line should be selected.
Into or out of the direction, so as not to cause under-cutting or over-cutting, affecting the processing quality.
Quantity.
(2) the radius of the arc at the corner between the side walls of the inner groove should not be too small, and the bottom of the groove is the same as that of the inner groove.
The fillet radius of the sidewall should not be too large. Machining the corners between the side walls of the inner groove with a milling cutter
At the arc, the arc radius r should not be too small; Groove bottom plane in milling parts
, the fillet radius r of the groove bottom and side wall should not be too large.
3 typical shaft parts processing technology design analysis
Take the shaft parts shown in figure 1 as an example. The blank is made of the following materials.
LY 12, φ40mm× 120mm aluminum alloy bars, and the parts are integrated with various tables.
Curved surface form, in the CNC lathe to complete the turning of such shaft parts, first of all,
First of all, process analysis should be carried out to determine the process plan. The technical scheme of the above part
As shown in table 1.
3. 1 fixture and clamping analysis
In terms of fixture selection, you can choose the most common fixture on CNC lathe.
Figure 1 typical shaft parts drawing