SU1694264A1 - Method of helical broaching - Google Patents

Abstract

The invention relates to the processing of metals by pressure, can be used in the production of hot-rolled seamless pipes for obtaining high-quality sleeves from a solid billet on piercing mills. The purpose of the invention is to improve the uniformity of the thickness of the wall of the sleeves. It is achieved by leveling the temperature of the workpiece in the deformation zone when the sleeves are pierced. The temperature of the workpiece in the deformation zone is measured and monitored and the roll rotation speed is kept constant. The uniformity of wall thickness increases. 1 tab.

Description

The invention relates to the processing of metals by pressure, can be used in the manufacture of hot-rolled seamless pipes for the production of high-quality sleeves from a solid billet on piercing mills.

The purpose of the invention is to increase the uniformity of the wall thickness of the sleeves.

The temperature of the metal being pierced is determined by the simultaneous flow of two processes: cooling the workpiece by radiating heat and contact with a cold tool and increasing the temperature due to the work of plastic deformation.

The temperature of the original workpiece along the length of uneven.

Measurement and control of the temperature of the workpiece in the deformation zone and change in the speed of rotation of the rolls are carried out.

keep it constant throughout the process.

Heated in the furnace to the temperature of the firmware, the workpiece is set in a spindle mill. The temperature of the workpiece is measured both after it is discharged from the furnace and in the mill. In order to obtain a uniform wall thickness of the sleeve, the temperature is kept constant throughout the entire time of deformation of the workpiece.

The temperature increment of the material being pierced (D TPl.) As a result of the work expended on plastic deformation and friction between the metal and the deforming tool is determined by the formula:

Atpd 0,07 (AKP ± MDIN) .0)

where mcr is the torque on the motor shaft, Nm;

Mdin - dynamic moment on the motor shaft, Nm;

t is the duration of the process, with;

p9 - the number of revolutions of the engine, rpm;

С - specific heat capacity of the sewn billet, J / (kg.grad);

G - weight of the workpiece, kg.

The Mkr and Mdin entering into formula (1) are directly fixed during the process with the help of a special device for controlling the energy-power parameters of the rolling process (ECAC) developed in the CS of the Academy of Sciences of the GSSR. With this device, the following parameters are also recorded: current strength, voltage, motor power, motor shaft rotation speed, flashing process duration.

The heat balance of the flashing process (A Tob) is expressed by the formula

ATOB LTPD- (ATK + DTV) (2)

where ATK is the temperature drop of the workpiece from contact with the tool and convection during the process, hail;

ATB - temperature drop of the workpiece as a result of cooling with water, hail; ATK is determined from the ratio

AT "

1 07Ј (-m) 4rts

3600 ®

where 1.07 is a coefficient that takes into account radiation;

Co is the blackbody radiation coefficient, W / m2K4;

Ј - the degree of blackness of the metal; F-radiating surface of the workpiece, m2; T is the temperature of the workpiece, deg. K. ATV is calculated by the formula

ATV -C & -)

where P - water consumption, kg / s;

ATVOD - increase in the temperature of water cooling the pipe-rolling tool, hail.

Example. According to the technological instructions, the temperature of the firmware of steel 45 and D is 1170-1200 ° C. In order to ensure the temperature value of the piercing in this range at the temperature of the workpiece set to rolls of 1070 ° C, the temperature increment due to the work of plastic deformation for the front end of the workpiece was 149 degrees. Such an increment is achieved according to formula (1) with an engine rpm of 160 rpm (roll rpm of 80 rpm). According to formula (2), the expected temperature increment is 110 degrees, and the firmware temperature is 1180 ° C, which was

fixed by photoelectric pyrometer (FEP),

For the rear end, at its temperature of 1120 ° C, the increment should be 60 degrees. According to the formula (1) given

the value of the temperature increment corresponds to the engine speed of 100 rpm (with a load). Temperature increment only as a result of plastic deformation transfer to heat

is 95 ° C. Taking into account the decrease in temperature, the total temperature increment will be 55 ° C, and the temperature of the firmware will be 1175 ° C.

Temperature equalization in process

firmware reduces the magnitude of the longitudinal raznesennosti sleeves. The data are given in the table.

The technological process is carried out as follows: before starting the firmware process, the temperature is measured at the front and rear ends of the workpiece by contact method in the case of flashing carbon steels or photovoltage for corrosion and scale-resistant workpieces.

steel grades. According to the magnitude of the temperature difference along the length of the workpiece, the speed mode of the flashing process is set to obtain an almost constant flashing temperature.

The firmware speed determination is performed using a computer with software based on formulas (1), (2), (3) and (4) and an actuator connected to the engine.

The introduction of the proposal will improve the uniformity of the wall thickness of the sleeves.

Claims (1)

Claims The method of helical firmware, including the deformation of a heated solid billet with spaced rollers on a mandrel with a change in the speed of rotation of the rolls, characterized in that, in order to increase the uniformity of the wall thickness of the sleeves, the temperature of the workpiece in the deformation zone and the change in the speed of rotation of the rolls are measured and controlled they are kept constant throughout the process. Comparative analysis of the firmware billet during rolling tubes 245 x 7 -9 mm, St, D, billet diameter 230mm, at the RMZ.