SU1437121A1 - Method and apparatus for producing tubes - Google Patents

Abstract

The invention relates to the processing of metals by pressure and can be used for the manufacture of pipes and tubular products. The aim of the invention is to increase productivity by reducing trimming. The method includes heating in the device 3 of the workpiece 2, its cross-screw firmware in the sleeve with technological thickening, charging the sleeve with mandrel 7 and pushing it on the mandrel through a block of irreducible calibers 10, removing the pipe from the mandrel and cutting the technological thickening. In the process of stitching the workpiece into the sleeve, the back end of the workpiece is continuously cooled with water and before pushing the cylindrical body of the mandrel is heated to a temperature of 300 -, while the front part of the mandrel with a length of 0.7 - 1.5 diameters has a temperature of not more than 50 C. Mandrel In this case, a composite is manufactured and includes a sleeve installed after the profiled toe, made of a material whose thermal conductivity is at least two times lower than the thermal conductivity of the toe and the cylindrical body, while the length of the mandrel of the mandrel is 0.7 - 1.5 of its diameter. 2 sec. f-crystals, 3 tab., 2 ill. (About SL

Description

ftt / e.f

114

The invention relates to the processing of metals by pressure and can be used for the manufacture of pipes and tubular products.

The aim of the invention is to increase productivity by reducing trimming.

Fig. 1 is a flow chart of the method; FIG. 2 shows a device for implementing the method.

. The method is carried out as follows.

The force is applied to the technological thickening of a smaller length. Reducing the length of the thickened part of the liner increases the efficiency of metal utilization by reducing the size of the trimmed pipe. The process on the mandrel, the cylindrical part of which is preheated to 300-500 ° C, and the front part 0.7 to 1.5 times the diameter of the mandrel, has a temperature of less, serves the same purpose. Heating the tail of the cylindrical mandrel is necessary

Initial rod 1 rubs to reduce pressure at contact me20

thirty

of the measuring length 2 and is supplied to the heating device 3. The heated billet is stitched into the sleeve with a technological thickening 4 at the helical rolling mill 5 with simultaneous heating of the back end of the billet by supplying water through the pusher 6, the cylindrical part of the mandrel 7 is heated in the furnace 8 to 300-500 s, while the front part of the frames-25 less than Ki is outside the heating zone and its temperature before defromation does not exceed 50 C.

The preheated mandrel is charged into the liner with the technological improvement on the charging device 9 and transmitted to the block of non-driven roll gauges 10, where dtenki of the sleeve is rolled by pushing it on the mandrel through the block of non-driving roll stands. Then, by means of a shooting, the mandrel 11 is removed from the pipe and the thickened end of the pipe 12 is cut off by the saw 13.

The method is implemented using a device which is a cylindrical mandrel 14 with a profiled nose 15, a shank 16 and a sleeve 17, which is made of a material whose thermal conductivity is at least two times lower than the thermal conductivity of the mandrel with an outer diameter equal to the diameter of the cylindrical body and installed behind the toe, the length of which is 0.7 - 1.5 times its diameter.

Continuous cooling of the rear end of the workpiece with water allows the temperature of the liner to be thickened to be lowered. The low temperature of the technological thickening predetermines an increase in the sorption of the metal deformation, therefore it is possible to push through the pin with the mandrel, preventing the metal from flowing in the longitudinal direction, and the prolonged contact of the hot metal with the cold mandrel leads to a decrease in the temperature of the pipe. a sharp increase in the pushing force; breaks in the pipe wall in the intercellular spaces. At the initial temperature of the mandrel before rolling

300 C, due to intensive cooling of the pipe, the process thickening is pierced or the pipe wall is ruptured due to significant pushing forces (Table 1).

Table 1 The effect of the heating temperature of the cylindrical part of the mandrel on the fraction of pipe trimming

40

290

45

50

300

400

500

510

3.5 3.0 2.5

Flashing of the technological thickening, rupture of the pipe wall

55

Mandrel Deformation, Mandrel Profile Distortion

The force is applied to the technological thickening of a smaller length. Reducing the length of the thickened part of the liner increases the efficiency of metal utilization by reducing the size of the trimmed pipe. The process on the mandrel, the cylindrical part of which is preheated to 300-500 ° C, and the front part 0.7 to 1.5 times the diameter of the mandrel, has a temperature of less, serves the same purpose. Heating the tail of the cylindrical mandrel is necessary

until pressure decreases at contact me0

0

5 less

taller with a mandrel preventing the metal from flowing in the longitudinal direction; in addition, prolonged contact of the hot metal with a cold mandrel leads to a decrease in the temperature of the pipe, a sharp increase in the pushing force, breaking of the pipe wall in the intercellular spaces. At the initial temperature of the mandrel before rolling

300 C, due to intensive cooling of the pipe, the process thickening is pierced or the pipe wall is ruptured due to significant pushing forces (Table 1).

Table 1 The effect of the heating temperature of the cylindrical part of the mandrel on the fraction of pipe trimming

290

300

400

500

3.5 3.0 2.5

Flashing of the technological thickening, rupture of the pipe wall

510

Mandrel Deformation, Mandrel Profile Distortion

At a temperature of over 1

 the magnitude of the resistance to deformation of the material of the mandrel becomes early — the pressure of the metal increases; plastic deformation of the mandrel occurs and its profile is distorted.

Thus, the temperature range of the tail section heating should be 300 - 500 ° C.

The use of a lower temperature of the front part of the mandrel (toe) as compared to the tail part makes it possible to create conditions for intensive cooling of the process thickening and for its tight fit on the front part of the mandrel. Calculations and experimental data show that over 5 to 10 seconds from the contact of the thickened part of the liner with the front part of the mandrel, which has a temperature of 30 -, temperature; and the metal falls by 100 - 250 ° C. At the same time, the technological thickening is tightly seated on the front part of the mandrel, the deformation resistance is sharply increased. Thus, it is possible to use liners with a shortened thickened part and reduce the amount of trimming, increase the utilization rate of the metal. If the temperature of the front part of the mandrel exceeds 50 Рс, then during the charging, transporting and stretching of the sleeve the temperature of the thickened end decreases slightly, the resistance to deformation also increases by an insignificant amount, when pushing through, the thickened end is pierced, the process is disturbed (Table 2).

Table 2 The effect of the temperature of the front part of the mandrel on the fraction of pipe trimming

Flashing of the technological thickening, rupture of the pipe wall

50 20

3.5 3.3

one

The length of the front non-heated part of the mandrel must be at least 0.7 of its diameter. With the length of the toe of the mandrel less than 0.7 of its diameter due to

a significant force applied to the technological thickening on the front of the liner when rolling pipes with a wall of less than 5.5 mm occurs

The firmware is thickened, the process is interrupted. The length range is selected from the conditions for obtaining pipes with a minimum wall thickness (up to 3.5 mm). In case of deformation with a length of technological thickening of 1.5, pipes with a wall of 3.5 mm can be pushed. The use of greater length leads to a significant waste of metal - the proportion of trimming increases, which can reach 4% or more. When the pipe wall is less than 3.5 mm, when pushing through the wall, it does not absorb the occurring tensile stresses; the process is broken and interrupted. Therefore, it is necessary to carry out a process on a mandrel, the length of the unheated front part of which is 0.7-1.5 times its diameter.

For the implementation of the pipe manufacturing method, the mandrel for pushing deformation must have a temperature distribution along the length according to the production method and keep this

35 distribution before charge and deformation of the liner. The mandrel is made integral with a heat insulating sleeve, ensuring that the temperature distribution during transportation is preserved.

40 sleeves to the charging device and to the mill. The heat insulating sleeve prevents heat transfer from the cylindrical part of the mandrel, having a temperature of 300 to 500 ° C, to the toe of the mandrel, which

45 has a temperature of less than 50 ° C

The use of a sleeve made of a material whose thermal conductivity coefficient exceeds the thermal conductivity of the nose and the cylindrical part is less than twice, does not provide sufficient thermal insulation, therefore, during the transportation of the mandrel and charging, the toe of the mandrel warms up significantly (by 100 - 250 ° C),

55 The elevated temperature of the nose of the mandrel leads to a slight increase in the resistance to deformation of the metal of the technological thickening, and to the firmware of the technological thickening

5 1437121, 6

(Table 2). The length of the toe of the mandrel is chosen for its diameter. Justification of the selected Taking into account the length of the front, non-heating-range of the lengths of the toe of the mandrel of the marginal part of the mandrel is 0.7-1.5 in the table. 3

5Table 3

The effect of the length of the front part of the mandrel on the receipt of pipes with the minimum possible wall thickness and the fraction of the pipe cut

0.6

0.7 1.2 1.5 1.6

Example 1. A billet of steel 60 with a diameter of 85 mm, a length of 195 mm was heated in an electric furnace to, then transferred to a two-roll helical rolling mill of MISiS 100D, where it was pierced into a sleeve with technological thickening. The piercer of the piercing mill is made with an axial hole through which cooling water was supplied to the rear end of the workpiece. The resulting sleeve had a diameter of 80 mm, a wall thickness of 10 mm, a length of 800 mm. The length of the process bulge on the front of the sleeve was 0.7 diameter mandrel (38.5 mm) or 41 mm. Thickening during firmware was obtained with the MO1ZI of a special device on the output side, which provides for the withdrawal of the mandrel from the deformation zone before the end of the firmware.

The mandrel consists of a cylindrical body with a diameter of 58.5 mm and a length of 3500 mm, a sleeve with a diameter of 58.5 mm and a length of 50 mm, a toe of a mandrel with a length of 41 mm (0.7 diameter of the mandrel), the profile of which corresponded to the profile of the piercing

2.0

2.8 3.5 4.0

Technological thickener firmware

Significant proportion of the cut of the total mass of the pipe.

Noah mandrel and shank with a diameter of 55 mm, a length of 70 mm.

Before deformation, the cylindrical body of the mandrel was heated in an inductor about the temperature, which was controlled by a contact thermocouple, the temperature of the toe of the mandrel was 40 ° C, the cylindrical body of the mandrel, the sock and the shank were made of steel U12, and the sleeve was made of steel 12X18H9T. The coefficient of thermal conductivity of steel U12 is 50 W M K,

and the coefficient of thermal conductivity of steel

12X18H9T - 14.5 watts. In this way, heat insulation of the nose of the mandrel from the heated cylindrical body is provided.

Pushing was carried out at the MYSIS 100P mill through four three-roll stands ZN-330. The finished pipe had an outer diameter of 67.5 mm, a wall thickness of 4.5 mm, a length of 3300 mm, and a thickened portion 40 mm long. After removal of the pipe from the mandrel, the process thickening was cut off with the mill backing, the mass of which amounted to 2% of the mass of the finished pipe.

 14371

Thus, a significant reduction in the proportion of trimming (2%) compared with the prototype method (4%) was achieved.

Thus, the proposed method - for the production of thin-walled mountains of rolled-up pipes (S 3.5 ... 4.0 mm) allows to significantly reduce the metal consumption.

The proposed method of pipe production and the device for its implementation increase the utilization rate of the metal to 0.965-0.98, g thereby increasing productivity, expanding the range of rolled pipes by rolling pipes with a wall thickness of up to 3.5 mm.

Claims (2)

1. Method for the production of pipes, including the cross-screw firmware solid heated billet in the sleeve with technological thickening, the subsequent deformation of it on the mandrel with - Q g 0 five 21 8 pushing through the block of non-driving roll gauges, removing the pipe from the mandrel and trimming the process thickener, characterized in that, in order to increase productivity by reducing the cut, the back end of the workpiece is continuously cooled during the washing process, and the pushing is done on a preheated mandrel, the front end of which, on a length of 0.7-1.5 diameters of the mandrel, has a temperature of less than 50 ° C, and the remainder part is 300-5PO ° C. 2. A device for producing pipes, comprising a cylindrical mandrel with a shaped nose and shank, characterized in that it is provided with a sleeve made of a material with a thermal conductivity not less than two times lower than the thermal conductivity of the mandrel and with an outer diameter equal to the diameter of the mandrel installed over the nose whose length is 0.7-1.5 times the diameter of the mandrel. 9ig.2