RU2773155C1 - Method for axial deformation of a fixed axisymmetric part and unit for implementation thereof - Google Patents

Abstract

FIELD: shaping.

SUBSTANCE: group of inventions relates to a method for axial deformation of a fixed axisymmetric part and to a unit for implementation thereof. The method includes fixing the part at two ends in the vertical position, performing axial deformation with simultaneous non-contact temperature control of the workpiece using a temperature sensor in the form of a thermal imaging apparatus, and cooling. Axial deformation is performed by means of automatically controlled power electric hydraulic drives with simultaneous automatic temperature control using a temperature sensor in the form of a thermal imaging apparatus, wherein the transition of elastic deformation to plastic deformation is simultaneously controlled by controlling the transition of the negative temperature of the part to the positive temperature of the part, the uniformity of temperature is estimated along the length of the part, and the average value thereof is taken as the average initial temperature of the part, the rate of temperature increase is then controlled along the length of the part, wherein when focal heating areas and neck formation areas appear, air blowing is automatically activated in order to cool the neck formation areas to the initial average temperature, the control and deformation cycles are then repeated until reaching a temperature whereat the axial plastic deformation equals ε=0.8 to 1%, and when a constant temperature rate is reached along the length of the part and focal heating areas are absent along the length of the part, deformation is stopped, and the part is automatically cooled at a uniform rate to ambient temperature. The unit comprises an air cooling control circuit including an air pump, controlled throttle valves and injectors, a temperature control circuit including a converter and a temperature sensor connected thereto in series, and a power plastic deformation control circuit including two electric hydraulic drives with gripping mechanisms.

EFFECT: increase in the stability of the size and shape of long-length low-rigidity parts, elimination of technological heredity, and minimisation of plastic deformation of the finished product in the operating period.

2 cl, 2 dwg

Description

The invention relates to engineering technology, in particular to plastic deformation methods of processing in the interval of mechanical operations, and can be used before the final processing of axisymmetric parts, for example: shafts, axles, rods, etc. There is a known method for processing long axisymmetric parts, including plastic deformation by stretching, taken as analog [1].

The disadvantage of this method is the plastic deformation sequentially in the areas between the grips. Temperature control is carried out by contact method in the center of the site. Cooling and unloading is carried out in sections. The discrete method of axial plastic deformation and uncontrolled cooling leads to an uneven distribution of axial residual stresses in sections and along the length of the part. The combination of shortcomings leads to a loss of geometric accuracy during the operation of the product.

The closest method to the claimed invention, selected as a prototype, is a method of thermal force processing of long axisymmetric parts, including deformation by axial force by automatic control of the power drive with feedback on the amount of deformation and automatic non-contact control of the heating temperature of the part. When the specified value of deformation is reached, the measurement and calculation of the uniformity of deformation along the entire length of the part is carried out. When the required value of deformation uniformity is reached, the heating of the part is turned off [2].

The disadvantage of this method is the control of uneven deformation only on the surface of the part, which does not allow to control the deformation in the cross section along its entire length in the process of force loading. The uniformity of deformation along the thread pitch on the surface of the part does not correspond to the uniformity of deformation over the section, and, consequently, the residual stresses over the section are uneven. Evaluation of unevenness by the average size of the treated areas reduces the accuracy of the measurement. The discrete method of axial plastic deformation leads to an uneven distribution of axial residual stresses in sections and along the length of the part. The combination of shortcomings leads to a loss of geometric accuracy during the operation of the product.

The problem to be solved by this invention is to improve the quality of manufacturing of blanks of low-rigidity axisymmetric parts with the following results: to increase the stability of dimensions and shape of long axisymmetric low-rigid parts by eliminating the direction of axial residual stresses remaining after the procurement operation; stabilization of the working efforts of deformation due to the choice of a rational loading scheme; destruction of technological heredity due to complete restructuring of the material structure by selective application of external tensile forces of the part, which leads to a more uniform distribution of axial residual stresses along the length of the part and leads to minimization of plastic deformation of the finished product during the operational period.

This problem is solved by axial deformation by means of automatically controlled electro-hydraulic power drives with simultaneous automatic temperature control. The temperature sensor in the form of a thermal imager simultaneously controls the transition of elastic deformation into plastic deformation by controlling the transition of the negative temperature of the part to the positive temperature of the part. Temperature uniformity is evaluated along the length of the part and its average value is taken as the average initial temperature of the part. Next, the rate of temperature increase along the length of the part is controlled when focal heating zones and necking zones appear, air blowing is automatically switched on to cool the necking zones to the initial average temperature. The control and deformation cycles are repeated until the temperature at which the axial plastic deformation is ε=0.8-1%. When a constant temperature rate is reached along the length of the part and in the absence of focal heating zones along the length of the part, the deformation is stopped and the part is automatically cooled at a uniform rate to the ambient temperature. The installation for axial deformation of a fixed axisymmetric part is equipped with two hollow semi-cylinders, which are installed relative to each other at a distance H=5d, where d is the diameter of the part. Nozzles are installed on the inner walls of the semi-cylinders, and controlled throttles are installed on the outer walls identical to the location of the nozzles. The outputs of the throttles are connected to the input of the injectors, and the outputs of the air pumps are connected to their inputs. Nozzles and throttles are placed evenly around the central axis of the installation in three rows with a step of 45° and along the length with a step of L=5d in each row, where L is the distance between the nozzles, d is the diameter of the part. The temperature sensor and transmitter are mounted on a separate rack. The outputs of the control unit include air cooling control circuits, which include: an air pump, controlled throttles and nozzles. The temperature control loop includes a converter and a temperature sensor connected in series with it. The control loop for force plastic deformation includes two electrohydraulic actuators with gripping mechanisms.

The control of a uniform two-sided force action ensures uniform deformation, which reduces the level of residual stresses of three kinds and reduces the relaxation time and stabilizes dislocation processes.

The use of a control loop for cooling the peak temperature zones of the workpiece material makes it possible to ensure the uniformity of axial residual and operating stresses, which eliminates warping of the workpiece axis during operation.

Non-contact control of peak temperature zones along the length of the part allows you to identify zones of neck formation, zones of uneven operating stresses, which eliminates the unevenness of axial residual stresses.

The present invention is illustrated by the drawings shown in Figs. 1-2. In FIG. 1 shows a general view of the installation for cooling long parts. In FIG. 2 shows section A-A of FIG. one

The method of axial deformation of the fixed axisymmetric part is carried out as follows. The part is installed in the center of the installation, rigidly fixed in the grips and installed between two sections of the installation with a gap equal to two diameters of the part. During axial deformation, hydraulic power drives are automatically controlled, and the tensile forces are directed in opposite directions. The part is heated by a controlled direct current source. At the same time, a temperature sensor is turned on - a thermal imager and the moment of transition of elastic deformation to plastic along the entire length of the part is controlled. At the moment of transition of the negative temperature of the part to the positive temperature of the part, the temperature uniformity along the length of the part is evaluated. And the average value is taken as the average initial temperature of the part. Next, the rate of increase in the temperature of the material of the part is controlled, and when zones of focal heating and necking zones appear, air blowing is automatically turned on. This ensures cooling of the zones of formation of necks to the initial average temperature. Next, the control and deformation cycles are repeated until the temperature when the axial plastic deformation should be within ε=08÷1%. Further, when a constant temperature rate is reached along the length of the part and in the absence of focal heating zones, the deformation of the part is stopped. To cool the part at a uniform rate to the ambient temperature, air blowing is automatically turned on in the thinning zones. The cycles are repeated subject to the appearance of new zones of thinning until deformation ε=1% is reached, at a constant rate of temperature change over the entire length of the shaft.

Installation of axial deformation of a fixed axisymmetric part for automatic cooling of heating zones of long low-rigid parts FIG. 1 and 2 contains two-section 2 and 2-1. Each section is installed relative to each other at a distance H=2÷3d, where d is the diameter of the part. The sections are made in the form of two hollow closed cylinder sectors. Nozzles 3 and 3-1 are installed on the inner walls of the sections, and controlled throttles 4 and 4-1 are installed on the outer walls, the inputs of which are connected to the input of nozzles 3 and 3-1, and the outputs of the throttles are connected to the outlet of the air pump 5. Nozzles and throttles are placed evenly along the perimeter of the part with a step of 45° and along the length with a step L=2-÷3d, where L is the distance between the nozzles installed along the length of the part. Item 1 is fixed with its ends in the gripping mechanisms in Fig. 1 are shown conditionally and rigidly fixed on the rods of electrohydraulic drives 6-7. Controlled direct current source for heating part 1 in FIG. 1 is not shown. A thermal imager 8 and a transducer 9 are installed on a separate rack (the rack is not shown in Fig. 2). Thermal imager 8 and converter 9 are connected in series and connected to the output of control unit 10.

Sources of information

1. RF patent No. 2709127, class. C21D 7/13, C21D 8/00, 2019.

2. RF patent No. 2615852, class. C21D 7/13, 2015.

Claims (2)

1. The method of axial deformation of a fixed axisymmetric part, including fixing the part from two ends in a vertical position, axial deformation with simultaneous non-contact control of the temperature of the workpiece with a temperature sensor in the form of a thermal imager and cooling, characterized in that axial deformation is carried out by means of automatically controlled electro-hydraulic power drives with simultaneous automatic temperature control with a temperature sensor in the form of a thermal imager, while simultaneously controlling the transition of elastic deformation into plastic deformation by controlling the transition of the negative temperature of the part to the positive temperature of the part, evaluating the uniformity of temperature along the length of the part and its average value is taken as the average initial temperature of the part, then control the rate of temperature rise along the length of the part, while when zones of focal heating and necking zones appear, air blowing is automatically turned on to cool the zones of neck formation to the initial average temperature, then the control and deformation cycles are repeated until the temperature at which the axial plastic deformation is ε=0.8÷1%, and when a constant temperature rate is reached along the length of the part and in the absence of focal heating zones along the length of the part the deformation is stopped and the part is automatically cooled at a uniform rate to the ambient temperature. 2. Installation for axial deformation of a fixed axisymmetric part by the method according to claim 1, containing a control unit, two electric hydraulic actuators, gripping mechanisms with two grippers rigidly fixed on the rods of electric hydraulic actuators, a non-contact temperature sensor and a converter, characterized in that the installation is equipped with two hollow half-cylinders, which are installed relative to each other at a distance H=5d, where d is the diameter of the part, while nozzles are installed on the inner walls of the half-cylinders, and controlled throttles are installed on the outer walls identical to the location of the nozzles, the outputs of which are connected to the injectors input, and the throttle inputs are connected to the output air pump, while the nozzles and throttles are placed evenly around the central axis of the unit in three rows with a step of 450 and along the length with a step L=5d in each row, where L is the distance between the nozzles, d is the diameter of the part, while the temperature sensor and the transducer installed on a separate rack, in outputs b The control unit includes an air cooling control circuit, including an air pump, controlled throttles and nozzles, a temperature control circuit, including a converter and a temperature sensor connected in series with it, and a force plastic deformation control circuit, including two electrohydraulic actuators with gripping mechanisms.

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