Application of the hottest machining method in com

2022-08-06
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With the successful development of the CAD/CAM system "computer graphics enhanced design and manufacturing software package" jointly developed by IBM and Lockheed, CAD technology has begun to move from two-dimensional plane modeling to three-dimensional modeling, so as to realize the quality calculation of parts, finite element analysis, NC machining programming and the generation of hidden three-dimensional drawings on a complete geometric model, It is also convenient to generate assembly drawings from the three-dimensional drawings of parts

3d solid modeling module ame of AutoCAD software package provides basic solid elements (voxels) for drawing stereoscopic drawings, including: cuboid, cylinder, cone, ball, torus, wedge, stretching body and rotating body of the innovative situation shape with core leading and convergent development formed by two-dimensional closed drawings. For some parts with simple shape, its stereogram can be completed by simple merging, intersecting and subtracting operations of several individual elements. However, for some complex parts, such as spatial cylindrical cam, worm cam, globoidal indexing cam, worm gear and screw connector, they all have complex spatial surfaces, so it is difficult to draw their three-dimensional drawings

the idea of this paper is to imitate the method of machining to draw the three-dimensional drawing of parts. No matter how complex the shape of a part is, as long as it can be machined, its three-dimensional drawing can be drawn by imitating its machining methods and steps. Mechanical processing is divided into hot processing (including welding, forging and casting) and cold processing (including turning, boring, milling, drilling, etc.). The basic operations for drawing the three-dimensional drawing of parts include merging, intersection and difference. Each hot working or cold working process of machining is equivalent to a parallel, intersection or difference operation when drawing the three-dimensional drawing of parts. For example, the "welding" process in hot working corresponds to the "merging" operation when drawing stereogram, and the "drilling" process in cold working corresponds to the "difference" operation, etc. Obviously, the more complex the shape of a part is, the more processes are required for processing. Similarly, the more merging, intersection and difference operations are required for drawing its stereogram. Sometimes, the surface of a part (such as a spatial cylindrical cam) is a complex spatial surface, which is generated by the relative motion between the tool and the part during machining. For such a part, when drawing its stereogram, it is necessary to realize multiple repeated similar operations through programming and program cycle

the following takes the spatial cylindrical cam as an example to illustrate how to imitate its processing method to draw the stereogram of the part. 2 part machining process for the spatial cylindrical cam shown in Figure 1, the machining process has about the following five processes:

(1) generating casting (or forging) blanks

cast (or forge) a cylinder blank with the required diameter and length with a mold

(2) machining inner holes

the diameter of the inner hole of the cam on the lathe is equal to the inner diameter of the cam, that is, the diameter of the camshaft

(3) chamfer

in order to install the cam on the camshaft conveniently, chamfer both ends of the inner hole on the lathe

(4) shaving keyway

a keyway for circumferential fixation of the cam is machined on the slotting machine

(5) machining the cam working surface

when machining the working surface of spatial cam, the relative motion between the tool center and the cam wheel blank is required to follow the change law of the coordinates of the tool center locus points. Generally, there are two machining methods: one is profiling method, and the other is NC machining method. When the profiling machine tool processes the cam contour, the tool center path is realized by using the profiling cam mechanism. NC machining is usually used for single piece or small batch manufacturing of precision cams or profiling cams (as shown in Figure 2). Young people should take the difficult environment as an opportunity to hone themselves. Fig. 1 spatial cylindrical cam

Fig. 2 NC milling of cylindrical cam

3 stereogram drawing process corresponds to the machining steps of spatial cylindrical cam. The stereogram is drawn by using the function of ame, as shown in Fig. 3. Fig. 3 drawing process of cylindrical cam stereogram A. forming matrix a0

generating cylindrical cam matrix A0 with function solcy1

b. dig out the inner hole b

use the function solcy1 to generate a cylinder B in the center of A0, and then use the function solsub to "difference" B from A0, and a1=a0-b is obtained

c. "chamfer" C1 and c2

use the function solcone to generate cones C1 and C2 at both ends of the inner hole of the matrix respectively, and then use solunion to combine C1 and C2, and remove the "difference" from A1 to obtain: A2 = A1 - (C1 ∪ C2)

d. "shaving keyway"

use the function solbox to generate a cuboid D, and "difference" from A2 to obtain: A3 = a2-d

e. form the surface

generate "tool" E1 (by solcy1) on the A3 surface, and "difference" E1 from A3. Rotate A3 by one step (generally 1 ° ~ 5 °), and then generate "tool" E2 at the appropriate new position along the tool center track according to a certain law, and "difference" E2 from A3. In this cycle, when A3 turns around, its contour surface is formed. A = a3-e1-e2-e3 -

finally obtained a is the stereogram of the cylindrical cam

4 program algorithm analysis using different algorithms will have a very important impact on the running speed of the program. For example, its advantage is the last step in the example of simple operation surface. When the program cycle is used to draw the working surface of the cam, the usual simple algorithm is: the cam base rotates a step around its axis, and then makes an auxiliary "tool". The "tool" moves a displacement along the cam axis according to the motion path required by the design, and the intersection of the cam base and the "tool" is calculated at this position, Then this intersection is "poor" from the cam matrix, and the metallurgical coal supply of the enterprise begins to appear a gap. The procedure follows this way

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