SU1235931A1 - Method of treatment of metalwork - Google Patents

Description

1235931

The invention relates to the processing of parts for reducing internal stresses, in particular to vibration processing, and can be used in the manufacture of products in the metallurgical industry, welding production, mechanical engineering and instrument engineering.

The purpose of the invention is to remove residual stresses.

FIG. 1 shows a diagram of the Transition type shell and shows the location of the nodal oscillation zones at the resonant frequency at the ends of the part (here 1 is the nodal points); in Fig.2 is a diagram of the shell with the end part (2 - the nodal points); in fig. 3 - detail scan (dotted line shows the nodal oscillation lines and the shape of the part oscillation determined at the resonant frequency, maximum in the range of operating resonant frequencies, with the slider 4 the optimum vibration input area is shown).

The method is implemented as follows.

A vibrator with an adjustable frequency of vibration action is installed on the structure in an arbitrary place. The range of operating resonant frequencies of the structure is determined by scanning the frequency of the vibration effect. From among the found resonant frequencies of the structure, the resonant frequency, the maximum in magnitude, is chosen and the structure is subjected to vibration. For Transition type details (Fig. 1), this frequency is f.

TO

When vibrating at this resonant frequency, the shape of the oscillation of the structure is determined, marking places with a minimum, almost zero amplitude of oscillations — the nodal lines and zones (Fig. 1). Find the surface of the structure with a minimum number of nodal zones. For transition, this surface passes along the small diameter face. In this case, the nodal lines intersect the surface at an angle and appear in the cross section in the form of nodal points (zones). Three nodal zones are located at the end of the small diameter (Fig. 1). The position of these nodal zones is marked on the structure, the vibrations are stopped and the vibrator is installed in one of the nodal zones of the found section, i.e. at the butt end of the diameter of the Transition type construction (Fig. 2). Further provo

d t full vibro-processing of the 1DII design, excites all the resonant frequencies of the operating dipone sequentially in a closed loop, and begin the cycle of vibro-processing at the resonant frequency at which the position of the oscillation input zone is selected, in particular, the transition from the frequency f is started for the transition. ,

Exposure of vibrations at the maximum magnitude of the resonant frequency of the working range of the resonant frequencies according to the shape of the vibrations of the structure determines the optimum position of the input of vibrations in the structure, i.e. in terms of the processing efficiency, the best place to install the vibrator on the structure or to mount the structure to be processed is

Q vibroplatform. Certainly

Thus, the input zone of oscillations corresponds to the hardest part of a complex structure among those whose eigenfrequency frequencies lie

5 in the working range of resonant frequencies. Moreover, if the working range of the natural resonant frequencies of the structure is not fully used due to the limited possibilities of using vibration equipment, the oscillation input zone found by the proposed method is optimal from the point of view of processing efficiency.

Entering vibrations into a structure, which is implemented in less rigid parts of it, during vibration treatment, reduces the intensity of vibrations of more or less rigid parts at the corresponding processing frequencies, i.e. reduces the efficiency and quality of processing of more rigid parts of complex structures.

An increase in the intensity of oscillations of more rigid sections of the structure due to an increase in the force of the vibration effect in a number of cases leads to an excessively high intensity of oscillations of less rigid parts of a complex structure, which leads to the appearance of cracks during vibration treatment. This requires a reasonable zone for introducing vibrations into a complex structure.

In addition, starting a treatment cycle at the resonant frequency, at which the position of the oscillation input zone is selected, it is possible to implement a soft processing mode for all zones and parts of a complex structure. It has

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the value at the beginning of the process of vibration treatment of parts of the structure, the peak values of the residual stresses in which reach the yield strength (for example, welds). The application of significant cyclic loads to such areas can lead to the appearance of cracks during vibration treatment. The reasonable choice of the vibration input zone and the initial resonant frequency of the treatment cycle makes it possible to control the initial treatment period for all parts of the structure with critical values of residual stresses.

Example. It conducts vibro-machining of a die-welded part of the Conic transition type 0 1010 x 0 720 x X 20 mm. Before carrying out the vibration treatment, the working range of the resonant frequencies is determined, which includes all the resonant frequencies of the part within the range of frequencies realized by the vibrating equipment used. In particular, for this detail, the range of operating frequencies excited by vibration equipment, 0-133 Hz, the resonant transition frequencies in this frequency range f ;, 87 Hz and f 112 Hz. Thus, the highest resonant frequency of the part in the operating frequency range is f 112 Hz. At the resonant frequency fj, the shape of the part oscillations is determined. It is sufficient to know the location with the minimum amplitude of oscillations — the nodal lines (nodal points, if viewed along the surface intersecting the nodal lines). The nodal zones in the sections drawn along the ends of the large and small transition diameters at the resonant frequency f2 are shown in FIG. 1. On the surface of a large diameter, their number is four, and on the surface of a small diameter - three. This means that the input of vibrations must be carried out from the end of the small diameter of the transition, and the best and more reliable mounting of the vibrator is realized in the intersection zone of the nodal line with the cross section of the small diameter of the transition, which has 3 nodal zones.

To compare the efficiency of introducing vibrations, the amplitude of vibrations of the ends of large and small diameters is measured at different resonant frequencies.

max with two options for the place of input vibrations (vibrator mount).

When installing the vibrator on the Transition in the nodal zone from the end of 5 large diameter, the amplitude of oscillations was obtained: A +0.5 mm of the small diameter end with A +2.5 mm of the large diameter end at the resonant frequency f (87 Hz, which is enough for an effective processing the end of the transition over a large diameter and clearly unsatisfactory for processing the end of a part over a small diameter. Attempting to achieve an increase in the amplitude of oscillations of the end

(5 small diameter by increasing the force of the vibration effect leads to an excessively high amplitude of oscillations of the large diameter end A +2.5 mm with AJ +10 mm, which

20 can lead to trash; in. - When entering from the side of a small diameter, the transition of the energy dissipation in the material of the part to internal friction allows vibro-processing to

25 higher amplitudes of oscillations of the butt of small diameter with a less significant increase in the amplitude of oscillations of large diameter. So, at the resonant frequency f, 87 Hz, the input of oscillations of the research institute from the end of a small diameter provides a uniform distribution of the amplitudes of the oscillations A 2.5 + 2.5 mm for h. +3 mm, which provides increased processing efficiency of the part and improves the quality of processing, i.e. reduction of time around-. working with a more uniform reduction of residual stresses over the part. Thus, the residual stresses are reduced by 60% both in the area of small diameter of the part and in the area of large diameter, in contrast to the known method, if the vibrator is attached to the end of a large diameter, when the reduction of stresses in the area of small diameter did not exceed 23%.

The use of the proposed method of vibration treatment of complex structures allows to obtain a more significant reduction in stresses in the most rigid parts of the structure, to obtain a more even distribution of internal stresses, which ensures a stable stability of material properties and reliable preservation of the dimensions of machined parts during their operation.

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Editor P.Cassey

Compiled by A. Kulemin Tehred L. Oleinik

Order 3062/24 Circulation 552Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, Projecto st., 4

Corektor V- But ha

Claims (1)

METHOD FOR PROCESSING METAL STRUCTURES, including mounting the vibrator on the surface, measuring the resonant frequencies of the structure, vibration from all resonant frequencies in series in a closed cycle, characterized in that, in order to remove residual stresses, after measuring the resonant frequencies, the structure is pre-vibrated at the maximum resonant frequency , determine the nodal zones on various surfaces of the structure at this frequency, and the vibrator is installed in the nodal zones of the surface with a minimum number of nodal zones. s <o SU ,,,, 1235931 A1 1 12