RU2418671C2 - Method of flat grinding with application of ultrasound oscillations - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to machine building and may be used for flat grinding of work pieces from various materials. Prior to grinding, workpiece is fitted in device for application of FM ultrasound oscillations. Because of said oscillations imparted to workpiece in grinding, cutting forces, contact and local temperature in zone of contact between abrasive grains and workpiece are reduced. Grinding over, workpiece and aforesaid device are removed from machine tool for workpiece to be subjected to ultrasound effects outside grinding zone. This allows removing residual stresses in workpiece surface areas and increasing efficiency since, at the time, another workpiece is ground.

EFFECT: grinding wheel longer life, higher processing efficiency.

1 dwg

Description

The invention relates to mechanical engineering, namely to processing by flat grinding of blanks from various materials.

There is a method of ultrasonic stabilization of residual stresses (see. Babenko MG. Improving the technology for ensuring dimensional accuracy of precision parts such as bearing rings based on the use of ultrasonic stabilization of internal stresses. Abstract of thesis ... candidate of technical sciences: 05.02.08. / Saratov State Technical University - Saratov, 2002. - 16 p.), in which after grinding the parts through the polished surface, ultrasonic vibrations (ultrasonic vibrations) of a certain amplitude and frequency are reported.

The reasons that impede the achievement of the technical result indicated below when using the known method include the absence of the influence of ultrasound energy on the grinding process of the workpieces, as well as an increase in the manufacturing cycle of the part due to the inclusion of time for ultrasonic stabilization of residual stresses. In the process of grinding and relieving residual stresses, various technological equipment is used. In addition, the drawback is the involvement of a relatively small number of dislocations in the process of dislocation absorption of ultrasound energy, the sizes of which lie in a narrow range, since the frequency dependence of the dislocation absorption is resonant in nature, and the intrinsic resonance frequency of the dislocation is determined by the length of the dislocation segment (see Ultrasound. Small Encyclopedia. / Under the general editorship of I.P. Golyamina. - M .: Soviet Encyclopedia, 1979. - 400 p.). This drawback is due to the fact that in the specified method, ultrasonic testing of a certain fixed frequency is used. As a result, the efficiency of removing technological residual stresses is small.

The closest to the claimed invention in terms of features is the grinding method selected as a prototype, which consists in the continuous application of ultrasonic vibrations to the workpiece during grinding (see US Pat. No. 2276004 C1, publ. 2006.05.10. Bull. No. 13, main. MPK index V24V 1/04 (2006.01) “Grinding method”).

The reasons that impede the achievement of the technical result indicated below when using the known method adopted as a prototype include the fact that in the known method, ultrasonic vibrations do not significantly affect the grinding process, since there is a local contact area of the tool to relieve residual stresses and the workpiece, and ultrasonic vibrations propagate over a limited volume of the workpiece.

The invention consists in the following. In the grinding process, the cutting ability of the grinding wheel is gradually reduced, which leads to the need for a corresponding decrease in the performance of defect-free grinding or (and) to a deterioration in the quality of the polished parts. One of the ways to improve the grinding efficiency of workpieces from various materials is to apply ultrasonic vibrations during grinding, in this case, to the workpiece. The application of ultrasonic vibrations allows to reduce the coefficient of friction in the contact zone of the circle-workpiece, cutting forces, contact and local temperatures, which leads to the preservation of the cutting ability of abrasive grains (AZ), and therefore, it is possible to increase processing productivity and the durability of the circle. In addition, during grinding in the surface layer of the workpiece, in most cases, tensile residual stresses are formed that adversely affect the performance of the product. One way to relieve residual stresses is by applying ultrasonic vibrations. In this case, the application of ultrasonic vibrations to the workpiece occurs both during grinding and after it is finished and the workpiece is removed, together with a device for implementing this method from the machine. On the machine it becomes possible to process the next workpiece. There is no need to install-remove the workpiece in the second device, since one device is used. This provides an increase in processing productivity and the efficiency of removing residual stresses.

The technical result is an increase in the durability of the grinding wheel and processing performance while ensuring the specified quality of the polished parts.

The specified technical result in the implementation of the method of flat grinding with superposition of ultrasonic vibrations includes the continuous superposition of ultrasonic vibrations on the workpiece during grinding.

The peculiarity lies in the fact that before grinding, the workpiece is installed in a device for applying vibrations, and ultrasonic vibrations are applied to the workpiece not only during grinding, but also after this process is completed and the workpiece is removed from the machine from the machine.

Due to the ultrasonic vibrations reported to the workpiece during grinding, the cutting forces, contact and local temperatures in the contact zone of the AZ with the workpiece are reduced. The reduction of local temperatures in the contact zone of the AZ with the workpiece allows you to improve the quality of the polished parts and to reduce the mass of metal deposits on the grains of the wheel, thereby increasing the durability of the grinding wheel and grinding performance. With a change in frequency, the wavelength changes, and the location of the vibration nodes will be unstable, therefore, the application of frequency-modulated ultrasonic vibrations to the workpiece ensures that all sections of the surface layer of the workpiece oscillate. The extended period of application of frequency-modulated ultrasonic vibrations to the workpiece allows maximum removal of residual stresses from the workpiece and improves the operational characteristics of the part. This is due to the fact that after grinding, the workpiece, together with a device for applying ultrasonic vibrations, is removed from the machine and frequency-modulated ultrasonic vibrations outside the processing zone are continued to be applied to it, thereby increasing the efficiency of removing residual stresses in the surface layers of the workpiece, and this time the next workpiece is processed on the machine. There is also no need to install and remove the workpiece in various devices. To communicate to the polished workpiece of ultrasonic vibrations of a frequency-modulated shape, an electric signal modulated in frequency is used, which can be obtained using an ultrasonic generator (USG).

The drawing shows a diagram of a device for implementing the method of flat grinding with the imposition of ultrasonic testing.

The device contains: frame 1, bracket 3, waveguide 4, body 5, screw 6, piezoelectric transducers 7.

The workpiece 2 is installed in the frame 1, tighten the screw 6 to the end of the waveguide 4. Frame 1 is installed on the magnetic plate of the machine. UZK are superimposed on the workpiece 2, and its processing is carried out with a grinding wheel. The elastic mechanical vibrations generated by the piezoelectric transducers 7, modulated in frequency, are communicated to the workpiece 2 through the waveguide 4. The waveguide 4 is attached to the housing 5, mounted in the bracket 3, rigidly connected to the frame 1. This solution allows the application of frequency-modulated oscillations on the workpiece 2 without hindering the grinding process. The imposition of 2 frequency-modulated ultrasonic vibrations on the workpiece provides the oscillation of all sections of the surface layer.

Thus, the workpiece 2 is communicated with frequency-modulated ultrasonic testing, which leads to a decrease in cutting forces, local temperatures, friction coefficient of the joint with the workpiece and a decrease in residual stresses arising during grinding.

After processing by grinding, the workpiece 2 together with a device for applying ultrasonic vibrations is removed from the machine, and frequency-modulated ultrasonic testing is continued to be applied to it outside the processing zone in order to relax the residual stresses in the surface layer of the workpiece 2.

Claims (1)

A method of processing workpieces with superimposed ultrasonic vibrations (ultrasonic testing), including installing the workpiece in a device for applying ultrasonic testing, flat grinding the workpiece on the machine and removing the workpiece with the aforementioned device from the machine, with the ultrasound being continuously applied to the workpiece during grinding and after it is finished and removed blanks with a device for applying ultrasonic testing from the machine.

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