SU1641506A1 - Method for turning shafts of low flexural rigidity - Google Patents

Abstract

The invention relates to mechanical engineering and can be used in high-precision machining of shafts and parts on computer-controlled machine tools. The aim of the invention is to improve the processing accuracy by preliminarily measuring the geometrical parameters of the corresponding sections of the surface of the shaft 1 by centering surfaces 4-6 lunettes and storing measured values into the memory, and during processing centering surfaces 4-6 lunettes move in the radial direction by an amount equal to measured corresponding to the surface of the shaft 1. 7 Il.

Description

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The invention relates to mechanical engineering technology and can be used in the high-precision machining of shafts and parts on machine tools with numerical control.

The purpose of the invention is to improve the accuracy of processing.

This goal is achieved by the fact that the measurement and insertion in the memory device of the relief of the shaft surface is carried out previously, and during processing the centering surfaces of the steady move in the radial direction previously measured,

Figure 1 shows the layout of the shaft in the lunette; Figures 2 to 5 of the diagram, according to the principle of measuring the relief of the shaft surface at idle, in Figures 6 and 7, turning the shaft processing circuit.

Shaft 1 is based in the mounting devices of the machine and in the rest 2 (see Figures 1.6 and 7). Lunette 2, presented in the form of a conventional kinematic scheme, contains a base 3 moving parallel to the axis of the shaft 1, centering surfaces 4–6 lunettes and modules 7–9. Centering surfaces 4–6 lunettes are conventionally depicted. They may not necessarily have physical contact with the shaft 1, the interaction can be carried out in a contactless manner. Modules 7-9 include displacement actuators and sensors for positioning centering surfaces 4-6 lunettes, as well as sensors that determine the force of their interaction with shaft 1.

During the measurement of the surface relief of the shaft 1, the rest 2 is moved to its original position, determined by the size LOT of the end face of the shaft 1 (FIG. 2). The centering surfaces 4-6 of the lunet move before interacting with the shaft 1 at the points a0, b0, c0 with some force, depending on the geometrical dimensions of the shaft 1, the quality of its surface, the fixing conditions and the mounting of the steady 2. For example, for the layout scheme of the lunet 2 given 1, it is necessary to consider the angular position of the shaft.

After that, the angular position of the shaft 1 is measured and its rotation is carried out with the simultaneous movement of the steady 2 nd by the required processing technology with a feed for one revolution of the shaft 1, similarly to what happens during thread cutting. At the same time, the centering surfaces 4-6 lunettes are moved so that the force of their interaction with the shaft 1 does not reach

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but i The shaft 1 is tracked.

In the initial position of the steady 2, the radial position of the centering surfaces 4-6 of the steady determines the corresponding radius vectors a0, bo and. When moving the lunet 2 with surface tracking, the radius vectors change due to the deviation of the shape of the surface of the shaft 1 from the ideal cylinder, the imperfection of its base conditions in the installation devices of the machine and other reasons.

Figures 2 and 3 show the trajectory of movement along the surface of the shaft of the centering surface 5 of the rest, corresponding to the supply S for one revolution of the shaft 1.

The tomki ai (i 0,1,2, ... 16) lying on this path are obtained as a result of successive fixation of the position of the centering surface 5 of the steady through 1/16 of the rotation of the shaft 1.

Fig. 4 shows the dependence a (0.3), reflecting the radial position of the centering surface 5 of the steady as a function of the rotation angle of feed S.

Figure 5 shows the same dependence in the form of the lattice function hell (в, S) of the function a ((6, S)) obtained by quantizing with a beat corresponding to 1/16 of the rotation of shaft 1.

Fig. 3 shows the spatial arrangement of the radius vectors of §i to the points ai. The radius vector a0 has a beginning at the point O, corresponding to the initial position of the steady 2, the radius vector ai - at the point lagging behind the point O at S / 16, the radius vector 32 - respectively at 2S / 16, etc.

When moving the steady rest 2 at idle, the radius vectors aj, B and 5j (j 0,1,2, ... n) describe, with some approximation, the relief of the surface areas of the shaft 1. with which centering surfaces 4-6 of the rest interact. To restore this relief by the sequence of its discrete values, it is necessary that the quantization cycle of the function a (v, 5} deeper (with S const) satisfies the conditions of the Kotelnikov-Shannon theorem.

Thus, in the memory device when moving the steady on the step length, an array of numbers is formed, describing the relief of the surface areas of the shaft 1, along which the centering surfaces 4-6 lunettes pass.

For processing, the steady rest 2 is returned to its initial position, shaft 1 is oriented from its initial position and processing is carried out with displacement of steady rest 2 so that the centering surfaces 4-6 of the steady rest along the trajectory of m - tracks that were idling. At the same time, the centering surfaces 4-6 of the rest are moved in the radial direction to the positions corresponding to the values stored for the given angular position of the shaft 1.

During machining of shaft 1, centering surfaces 4-6 lunettes in each arbitrary state occupy the same position as at idling, the curvature of the axis of rotation of shaft 1, due to the error in shape and position of its surface, does not occur, thereby providing increased machining accuracy .

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Claims (1)

Claims. The method of turning shafts with low bending stiffness, which includes acting on the shaft of centering elements of a steady moving parallel to the shaft axis, characterized in that, in order to improve machining accuracy, the advance of the steady motion is carried out, affecting the shaft of a steady centering elements on the shaft and the radial position of the centering elements at certain positions of the shaft being machined, returning the shaft and the steady back to the initial position and mechanically machining the shaft with a feed equal to the feed of the steady at the preliminary stage, and the position of the centering elements at the said points of the shaft is set equal to the previously determined one. 8 9 S and about au - 1 -U / g g FIG. 2 Fig.Z dg t№). but" About 1 2 FIG. five at FIG 4 g 16 in FIG. 6 Schi g L eight