Determination of NC milling processing route in th

Case: Determination of NC milling processing route

Abstract: Determination of NC milling processing route (examples of three typical parts) in NC machining, the motion path and direction of the tool (strictly speaking, the tool location) relative to the workpiece is called the processing route. That is, the path that the tool passes from the beginning of tool setting to the end of machining, including the path of cutting and the non cutting empty travel such as tool introduction and return. The determination of processing route must first ensure the dimensional accuracy and surface quality of the machined parts

the determination of NC milling processing route (three typical parts for example)

in NC machining, the motion path and direction of the tool (strictly speaking, the tool location) relative to the workpiece is called the processing route. That is, the path that the tool passes from the beginning of tool setting to the end of machining, including the path of cutting and the non cutting empty travel such as tool introduction and return. The determination of machining route must first ensure the dimensional accuracy and surface quality of the machined parts, and then consider that the numerical calculation is simple, the cutting route is as short as possible, and the efficiency is high

the following is an example to analyze the commonly used processing routes when NC machine tools process parts

(1) analysis of contour milling processing route

for continuous milling contour, especially when machining arc, the export amount should be $25.574 million. Pay attention to arranging the cutting in and cutting out of tools, and try to avoid repeated processing at the junction, otherwise obvious boundary marks will appear. As shown in figure a below, when milling the excircle with arc interpolation, it is necessary to arrange the cutter to enter the circumference milling processing from the tangential direction. When the excircle processing is completed, do not withdraw the cutter directly at the tangent point, but let the cutter move for a longer distance, and it is best to withdraw along the tangent direction, so as to avoid the collision between the cutter and the workpiece surface, causing the workpiece to be scrapped when canceling the cutter compensation. When milling the inner arc, the principle of cutting in from the tangential direction should also be observed, and the transition arc should be arranged to cut in and cut out, as shown in Figure B

a)

b)

(2) analysis of the processing route of the surface

for the ruled surface with open boundary, the ball head cutter is often used for "line cutting" processing, that is, the tangent path between the tool and the part contour is a line, and the line spacing is determined according to the machining accuracy requirements of the part. For the large engine blade shown in the figure, two processing routes can be used. When using the processing scheme in figure a, each time machining along a straight line, the calculation of the tool location is simple, the program is few, and the processing process is consistent. Through the superposition of the curve, the characteristics of the sample are compared and the formation of the ruled surface can accurately ensure the straightness of the bus. When the processing scheme shown in Figure B is adopted, it conforms to the data given by such parts, which is convenient for inspection after processing. The accuracy of leaf shape is high, but there are many procedures. Because the boundary of curved surface parts is open and there are no other surface restrictions, the curved surface boundary can be extended, and the ball head cutter should be machined outside the boundary

(3) hole system processing route

for hole system processing with high positional accuracy requirements, special attention should be paid to the arrangement of hole processing sequence. If the arrangement is not correct, it is possible to bring in the reverse clearance along the coordinate axis, which will directly affect the positional accuracy. As shown in the figure, figure (a) is a part drawing. Six holes with the same size are machined on this part, and there are two processing routes. When machining according to the route shown in figure (b), because the positioning direction of holes 5 and 6 is opposite to that of holes 1, 2, 3 and 4, the reverse clearance in the Y direction will increase the positioning error, taking North America as an example, affecting the position accuracy of holes 5 and 6 and other holes. According to the route shown in figure (c), after machining 4 holes, move up a certain distance to point P, and then turn back to process 5 and 6 holes. In this way, the direction is consistent, which can avoid the introduction of reverse clearance and improve the position accuracy of 5 and 6 holes and other holes

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