RU2585920C2 - Method for metal forming - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy and can be used in metal forming. To reduce resistance of metal forming and amplifying relaxation processes on moving wire or strip workpiece, deformation zone is simultaneously exposed to microwave radiation and pulse current in lengthwise direction along workpiece causing electroplastic effect in metal at amplitude of current density J_m approximately 10³ A/mm², pulse duration τ approximately 10^-4 s and pulse repetition rate of several hundreds of Hz depending on speed of workpiece. Method provides short-term stop active deformation in order to prevent premature strengthening and for enhancing at same time effect of microwave radiation and pulsed current up to 30 % due to spin softening and electroplastic effect.

EFFECT: as a result of microwave radiation third component of electroplastic effect is amplified in form of spin softening metal, apart from action of "electronic wind" pulse current, plasticising metal, and pinch effect of proper current magnetic field creating vibration of metal.

1 cl

Description

The invention relates to the metallurgical industry. It can be used for various operations of metal forming in ways of softening and reducing resistance to deformation locally on moving workpieces or in all their volumes in the absence of movement of the workpiece.

A known method of processing metals by pressure [RF patent No. 2321469, M. cl. B21C 25/00, filing date 02.09.2005, published 04/10/2008 (prototype)], close to the invention in terms of technical nature and the achieved positive effect, which consists in deformation of the workpiece:

- stretching with drawing through carbide dies;

- rolling between counter-rotating deforming shafts with mechanical compression pressure;

- stamping of sheet material;

- ultrasonic conditioning in the standing ultrasonic wave mode with the simultaneous action of a pulsed current, creating an electroplastic effect.

As is known from the scientific and technical literature, the electroplastic effect is a cooperative phenomenon and consists of three main parts:

- the action of the "electronic wind" of the pulse current;

- pinch action of the own magnetic field of the current;

- spin softening caused by the electron paramagnetic effect in the metal.

The disadvantage of this method is the poor development of the third component of the electroplastic effect due to electron paramagnetic resonance and spin conversion of pairs of free electrons localized on paramagnetic impurities in the metal and on the dislocations involved in its plastic deformation.

The objective of the invention is to enhance the specified component of the electroplastic effect due to the use together with the pulsed current of microwave radiation as an additional energy effect on the deformable metal, as well as the presence of an independent influence of the microwave radiation factor on the plastic deformation of the steel billet with the determination of the technical significance of this effect, which, along with the action of a pulsed current can independently reduce the metal resistance to deformation and enhance relaxation in it nye processes under conditions of short stops deforming active samples (blanks) and the associated premature hardening of the metal.

This goal is achieved by the fact that in the proposed method, the electroplastic processing of steel billets of steel grade 12X18H10T by pressure is carried out in conjunction with the action of microwave radiation on the billets, which causes electron paramagnetic resonance and enhances the spin softening of the metal, characteristic of the electro-plastic deformation of steel.

The technical result is achieved due to the fact that a pulsed current with an amplitude density of (0.5-1) 10 ³ A / mm ² , a pulse duration of (1-2,5) 10 ^-4 sec, and also with a frequency is passed through a mechanically deformable workpiece. pulse repetition, determined depending on the speed of movement of the workpiece according to the formula V = Lxν, where L is the length of the plastic processing zone and ν is the frequency of repetition of current pulses, microwave irradiation of the deformable zone in the transverse direction is carried out. In addition, it is possible to process by current and microwave irradiation of the deformable workpiece with static loading of the workpiece, for which the deformation of the workpiece is periodically stopped for 1-3 minutes, and the energy effect is continued.

The workpiece was subjected to plastic deformation. Upon reaching the load in the range of 0.16-1.45 kN, a pulse current was passed with an amplitude density (0.5-1.0) 10 ³ A / mm ² , pulse duration (1-2.5) 10 ^-4 sec and a repetition rate pulses, determined depending on the speed of the workpiece under the condition V = Lν, where L is the length of the plastic deformation zone, mm, ν is the repetition rate of current pulses, Hz, and at the same time, microwave irradiation of the deformable zone of the workpiece was carried out. In stress relaxation experiments, the workpiece was treated with single current pulses. The working part of the sample was 28 mm.

When metal forming, the recommended speed is not more than 1 m / s, the recommended length of the plastic processing zone is 10-50 mm. When determining the frequency of the pulse current in the processes of working through all sections of the workpiece moving through the deformation zone, it is possible to recommend a pulse fill factor of this zone equal to two, then the frequency of the pulse current (in accordance with the indicated formula) will be (ν = V / L) from 20 to 100 Hz

The tests showed:

1. after the machine drive stops in the first 2-3 seconds of stress relaxation, the combined action of the current and microwave radiation when the field component E is oriented transversely to the sample axis creates a load drop (taking into account the thermal effect) 10-12%;

2. the load drop over a 3-minute relaxation pause under the action of only current pulses amounted to 16.8-17.5%. Under the action of only the transverse field E of the microwave radiation, the effect of the load drop was 11.2–11.4%. Under the combined action of current and microwave radiation, the effect of a load drop (field E transverse to the axis of the sample) was 21.9-22.5%;

3. Under the action of only a longitudinal field E of microwave radiation, the effect of the load drop was 11.9-12.3%. In tests with the combined action of current and microwave radiation and the longitudinal orientation of the field component E relative to the axis of the sample, the effect of the load drop was already 29.8-30%.

The proof of the feasibility of the practical implementation of the proposed method and the achievement of a positive result was carried out by comparative analysis of the proposed method with the prototype when conducting experiments with models, which were used thin samples-spatulas from stainless steel 12X18H10T by stretching (plastic deformation) of the samples at a constant speed with the inclusion of relaxation pauses applied voltages by turning off the drive of the test machine without unloading the samples.

It was found that the claimed method of metal forming in the form of stretching the samples at a constant speed differs from the prototype by an additional decrease in the metal resistance of electroplastic deformation by 10-17.5% when exposed only to current pulses. Under the influence of only microwave radiation on the processes of plastic deformation, the effect of a load drop is about 11.2-12.3%. An increase in voltage relaxation up to 30% occurs upon the combined action of current and microwave radiation and the longitudinal orientation of the field component E relative to the axis of the sample.

Using the proposed method of metal forming by pressure with the action of both pulsed current and microwave radiation in the deformation zone allows intensifying the process of electroplastic metal forming by pressure to a greater extent than with conventional metal processing by pressure without current or with the action of only pulsed current in the plastic deformation zone.

Claims (2)

1. A method of processing steel billets by pressure, including plastic deformation of the billet and simultaneous exposure to it by a pulse current, characterized in that the pulse current is applied with an amplitude density of (0.5-1) 10 ³ A / mm ² , pulse duration (1- 2.5) 10 ^-4 s and pulse repetition rate, determined depending on the speed of the workpiece according to the formula V = L · ν, where L is the length of the plastic processing zone and ν is the frequency of the current pulses, and simultaneously conduct microwave irradiation of the deformable harvesting zones . 2. The method according to p. 1, characterized in that the plastic deformation of the workpiece is carried out with a periodic stop for 1-3 minutes, and during periods of stopping it is affected by pulsed current and microwave radiation.