SU802004A1 - Method of superfinishing the surfaces of bodies of revolution - Google Patents

Description

one

The invention relates to the field of finishing surfaces of rotation, for example, bearing rings.

The known method of superfinishing of the surfaces of parts of rotation in which the part is rotated and the tool is pressed against it and moved along the generatrix of the treated surface, while the tool is given ultrasonic vibrations and a low-frequency oscillating motion.

one.

In the known method, the pressing force of the tool to the part is set, without taking into account the geometry of the generator of the machined surface, and the required geometry (convexity) is provided by the tool stands at the ends of the stroke, which does not provide the required geometric shape.

The aim of the invention is to provide the desired geometric shape of the product.

The goal is achieved by the fact that the pressing force of the tool is changed within the stroke of the bar, while the frequency of ultrasonic vibrations is chosen within 18-44 KHZ with amplitude from 1 to 10 µm, and the nominal pressing force

Kremchi carbide and electrocorundum tools are set in the range of 2-30 kg / cm and 20-100 kg / cm for tools made from diamonds and cubic boron nitride.

FIG. 1 shows a sketch of the details and profiles forming the treated surface; in fig. 2 — arrangement of the device for carrying out the method; in fig. 3.4 and 5 - device modifications; in fig. 6 is a graph of the relationship between the metal removal and the amplitude of ultrasonic vibrations.

five

The essence of the method is explained in Fig. 1, in which in the upper left corner there is a sketch of a part, in this case an inner ring of a tapered roller bearing with a generator

0 of the machined surface of the battery as well as the tool, and on an enlarged scale, the profiles of the workpieces, the parts after the trial processing, and the specified profile of the part.

5 These profiles are presented in rectangular coordinates, while the abscissas X, the current sections of the part in the interval from Xo (point A) to X, (point B), are plotted on the abscissa,

0 and the ordinate is the radial positions of the points of the corresponding profiles; the scale on the ordinate axis is approximately two orders of magnitude larger. The scale on the abscissa axis. The specified AB profile details according to the operating conditions of the bearings must be linear or convex within the tolerance for the size of the finished part. The profile of the workpiece is separated from the specified profile by the value of & allowance, which is determined from the condition of removal of the defective layer, due to the conditions of pre-treatment (grinding). To carry out the machining, the part is rotated, the surface to be machined is elastically pressed into a tool, which is accompanied by an envelope-alternating feed movement along the generator L-B, and the oscillations are reported with a frequency of 18-44 kHz and an amplitude of 1-10 microns. In addition, a low-frequency oscillation motion along generator A-B can be reported to the instrument, for example, with a frequency of 2-50 1 / s and an amplitude of 0.1-3 mm. The nominal pressing force of the tool is set from the conditions of maximum performance, this force is 2f30 kgf / cm for silicon carbide and electrocorundum tools or 20-100 kgf / cm-dl of diamond and cubic boron nitride tools. During the pressing process, the pressing force is maintained nominal in areas with a maximum distance U, between the profile of the workpiece and the specified profile of the part; on the rest of the plots, this force is reduced as a function of the current removal difference in the nominal mode and the specified removal in this current section X,. The mode of such a reduction in the pressing force can be carried out as follows. At least one test piece is preliminarily processed at the nominal mode, the processing of the test batch is preferable, thus eliminating the random errors of individual blanks. Workpieces are measured before machining, and finished parts after trial processing; this allows you to determine the corresponding profiles (top and bottom lines in FIG. 1) and for each of the current sections X, determine the actual removal of b. Next, as a function of the current spacing (H - t} removal in nominal mode and specified removal It is also possible to carry out machining with continuous measurement of the radius in the current section X and set the value for reducing the nominal force of pressing the tool to the part, a function of the allowance to be removed in each section. It is possible to lead with a change in the pressing force of the tool when it moves in one direction and keeping it constant during the machining motion 1, this modification of the method is feasible when the tool is fed at an acute angle to the generator. A device for carrying out the method with a superfinish of part 1 contains (see, FIG. 2) the spindle 2 and the tool pressed to the machined surface 3 - an abrasive bar 4, which is pasted on a mandrel 5 fixed in a magnetostrictive transducer of ultrasonic vibrations 6 connected to an ultrasound gene RATOR 7, Converter B is rigidly connected to a quill 8 mounted in guides 9 of a support 10 and rigidly connected to a piston of a hydraulic cylinder 11, Guides 12 of a longitudinal course of a support 10 parallel to a generatrix 3, guides 9 perpendicular to guides 12 to a cylinder 11, a pipeline 13 is connected. A hydraulic cylinder 14 with a piston 15 rigidly connected to the stem 16 is also mounted on the caliper 10. The hydraulic cylinder 14 is connected to the hydraulic system of the machine through pipe 17 (opening 18) and to the drain pipe 1E. At the end of the rod 16 is fixed the roller 20, pressed against a fixed copier 21 with an adjustable profile attached to the machine bed. In the modification in FIG. 3, the device includes a sensor 22 of the shape of the generator surface 3 mounted on the bracket 23, the computing unit 24, the setting unit 25, the amplifier 26 and a reversing motor 27, on whose shaft a gear 28 is attached, is connected to a rack 29, which is rigidly connected to the rod 16. The modification of FIG. 4 is equipped with a throttle 30 and a check valve 31; In addition, the guides 12 form an acute angle with the part 3 of the component 1 forming the surface. In the modification of the device of FIG. 5, a crane 32 is provided with a lever-handle 33, the crane 32 is fixed to the caliper 10 and held in the middle position by springs 34, Fixed stops 35, mounted on the frame of the machine, interact with the lever 33. The device operates as follows. Upindel article 3 (FIG. 2) with fixed part 1 is brought into rotation; Caliper 10 is reported to oscillate and longitudinal feed motion. Include ultrasonic generator 7 and through the transducer

6, ultrasonic vibrations are communicated to the instrument 5 by the tool. 4 The pipes 17 and 13 supply fluid to the hydraulic cylinder 11 and press the tool 4 to the part 1, moving the quill 8 in the guides 9. The pressing force of the tool is proportional to the pressure of the hydraulic cylinder 11 It depends on the degree shut off the bore 18 with the piston 15. With the fully closed bore 18, it is the greatest and equal to the pressure in the hydraulic system, which is set by the pressure valve, not shown in the figure, but with the fully open valve, the smallest. The degree of overlap of orifice 18 depends on the movement of piston 15 and rod 16 when roller 20 rolls on copier 21. With varying shape of copier 21, the degree of overlap of orifice 18 changes when the caliper 10 is fed longitudinally, respectively, the pressing force of tool changes. The shape of the copier is adjusted according to the results of processing the test parts.

The device, the image; nns) and on. 3, works similarly. The signal from the sensor 22 and the nporpaMtviHoro device 25 is processed in the computing device 24, which generates a command coming through the amplifier 26 to the actuator 27. The actuating element 27, turning gear 28, moves the rail 29 and the switches 16 that are rigidly connected to it; the remaining elements work in the same way as in the modification of FIG. 2

In a modification of the device shown in FIG. 4, the longitudinal feed of the caliper 10 at an angle to the generator surface 3 causes the tool 4 and the hydraulic cylinder 11 connected to it to move in the radial direction. In the longitudinal feed from left to right, the piston pushes the liquid out of the hydraulic cylinder 11 through the throttle 30 and the pressure in the hydraulic cylinder increases; in the longitudinal flow from right to left, the liquid enters the hydraulic cylinder 11 through the throttle 30 from the pipe 17 and the pressure on the piston decreases. Thus, the clamping force of the bar 4 to the part 1 on the right edge of the surface 3 is less than on the left. Valve 31 operates at

rebound of tool 4 after finishing the treatment,

In the modification of the device of FIG. 5, when the caliper 10 is fed longitudinally, the crane 32 is switched when the handle 33 is mounted on the stop 35. In this case, the pipe 13 is disconnected from the drain (through the openings 18 and 19) and the pressure in the hydraulic cylinder 11 increases.

Other modifications of the devices are possible, for example, using the pneumatic clamp of the tool together with the hydraulic clamp. Variable pressure on the bar can be created by means of a spring.

The proposed profile control method can be used not only with an ultrasonic super finish, but also with any other super finish method, when there is a one-to-one correspondence between bar pressure and metal removal.

Using the described method allows to increase the geometrical accuracy of the machined parts.

Claims (1)

1. Mazalsky V.N. Super Finishing Machines L ,, Mechanical Engineering, 197, 17.52-53. -S L, X P FIG. 2 ffm hydraulic system fut.