JPH01309756A - Method and apparatus for continuously casting metal tube - Google Patents

Abstract

PURPOSE:To prevent the development of crack on surface of a drawing tube by pushing back length more than the length corresponding to the solid shrinkage rate of the casting tube at the time of stopping the drawing into a mold apparatus after stopping the drawing. CONSTITUTION:As continuous casting method for the metal tube 14, the molten metal holding in a molten metal holding furnace 11 is solidified into pipe-state with the mold apparatus 10 to form the casting tube 14 and this casting tube 14 is drawn from a drawing device 16. Then, it is repeated as one cycle that the tube 14 is drawn during drawing time and stopped during waiting time after drawing and the length corresponding to the heat shrinkage rate to the casting tube 14 at interval from the casting device 13 to the drawing device 16 is pushed back during pushing back after stopping. Therefore, even if the crack is developed on the solidified cast billet in the mold, the crack is eliminated under pushing back action. In this result, the development of the crack on the surface of the casting tube 14 after completing drawn casting, is eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to i! ! ! The present invention relates to a continuous casting method and apparatus.

[Prior art] Regarding the continuous casting method of metal tubes, Japanese Patent Application Laid-Open No. 60-542
As described and accomplished in Publication No. 55, a mold device is installed at the pouring port of a molten metal holding furnace, the molten metal is cooled in this mold device to form a cast tube, and the cast tube is pulled out by a drawing roller device. to cast.

By the way, in the continuous casting of metal pipes, as in the continuous casting of solid slabs, when solidified slabs are continuously pulled out, fractures occur from the weak parts of the solidified cores, resulting in breakouts at the mold exit. . Therefore, even in continuous casting of metal tubes, it is useful to employ intermittent drawing in which drawing and stopping are repeated as one cycle.

[Problems to be Solved by the Invention] However, when the above-mentioned intermittent drawing is "simply" adopted for continuous casting of metal tubes, solidification shrinkage of the slab that occurs in the mold during the cooling process when drawing is stopped is large. , causing cracks on the surface of the cast tube.

An object of the present invention is to stably draw and cast a cast pipe without causing cracks on its surface.

[Means for Solving the Problems] The present invention as set forth in claim 1 is characterized in that a molten metal contained in a molten metal holding furnace is solidified into a tubular shape in a molding device to form a cast tube, and the cast tube is pulled out by a drawing device. In the continuous casting method for a metal tube to be drawn, the cast tube is pulled out during a drawing time, stopped during a waiting time after this drawing, and during a pushing time after this stop,
Thermal acid 1i for pI pipe making from molding equipment to drawing equipment! Pushing in a length corresponding to the amount is repeated as 1 cycle.

The present invention according to claim 2 includes a mold device that is disposed at a pouring port of a molten metal holding furnace and that solidifies the molten metal into a tubular shape to form a cast pipe, and a mold device that forms a cast pipe by pulling out the cast pipe formed by the mold device. A continuous casting apparatus for metal tubes having a drawing device, a temperature measuring device for measuring the mold outlet temperature Tl of PJ pipe making and the average temperature T2 between the mold outlet and the drawing device, and the above-mentioned casting tube. Pulling out during the drawing time, stopping during the waiting time after this drawing, and during the pushing time after this stop, pushing the tube by a length A or more corresponding to the amount of heat shrinkage of the cast pipe from the mold device to the drawing device. 1 cycle, and the control device controls the temperature measurement results Tl and T2 . The above A is calculated as A=L.alpha.(Tl-72) based on the distance between the mold outlet and the drawing device and the coefficient of linear expansion a of the cast tube.

[Function] According to the inventor's study, cracks that occur on the surface of a cast pipe that has been intermittently drawn are caused by the state in which the inner surface of the cast pipe, which solidifies and shrinks significantly when drawing stops, is strongly adhered to the core of the mold device. Below, the cast tube pulled out of the mold undergoes a large solid contraction due to the cooling effect from both the inside and outside of the tube, and this solid shrinkage force is applied as a tensile force to the immediately solidified slab that is strongly adhered around the core as described above. And as a result, cracks such as tearing occur on the surface of the slab A.

According to the first aspect of the present invention, a length of the cast tube corresponding to the solid yield e at the time of stopping the drawing is pushed into the mold device after the drawing is stopped. Therefore, even if a crack as described above occurs in the solidified slab in the mold, the crack will be repaired under the above-mentioned pushing action, and as a result, the surface of the cast pipe after pultrusion casting is completed. No more cracks.

Further, according to the present invention as set forth in claim 2, the withdrawal stop 11
The above solid acid 1i of PJ Pipe Manufacturing at the time! After accurately calculating the length A that corresponds to i, the pushing control as described above is performed, and the occurrence of cracks can be reliably prevented.

[Example] Fig. 1 is a control system diagram showing one embodiment of the present invention, Fig. 2 is a sectional view showing a PI type device, Fig. 3 is an end view showing a mold device, and Fig. 4 is a control system diagram showing an embodiment of the present invention. Schematic diagram showing intermittent pulling operation, No. 5
The figure is a speed diagram showing the intermittent drawing operation of the present invention.

As shown in FIG. 1, the continuous casting apparatus 10 includes a molten metal holding furnace 1.
A mold device 13 is attached to a casting hole 12 formed at the lower side of the mold. The continuous casting device IO is a mold device 1
3, the molten metal is cooled to form a casting tube 14, which is drawn and cast.

The continuous PI manufacturing device 10 includes guide rollers 15 that support the casting tube 14 on the outlet side of the mold device 13, and
A drawing roller device 16 for drawing the cast tube 14 is provided. The pulling roller device 16 consists of a pinch roller 17 and a press roller 18. In addition, the pulling roller device 1
6 is a hydraulic motor 1 driven by a hydraulic pump 16A.
The pinch roller 17 is driven by this hydraulic motor 1.6B, and as a result, a pulling force is applied to the cast pipe 14.

As shown in FIGS. 2 and 3, the mold device 13 is composed of a mold 19 made of graphite and a core 20 also made of graphite. A core holding inner diameter part 21 is provided at the inner diameter part 21, and an inner diameter part 22 for forming the outer surface of the tube is provided around the center axis of the mold extending substantially over the entire length excluding the core holding inner diameter part 21.

The core 20 is inserted into the mold 19, and the flange portion 2 is fitted into the core holding inner diameter portion 21 of the mold 19 at the end on the molten metal inflow side.
3, and a pipe inner molding outer diameter part 24 that is provided around the mold center axis over substantially the entire length excluding the flange part 23 and forming a pipe molding passage 25 between the pipe outer molding inner diameter part 22 of the mold 19. Be prepared. The core 20 also includes molten metal injection passages 26 communicating with the tube forming passage 25 at each of a plurality of positions M (four positions in this embodiment) around the mold center axis in the flange portion 23 . Each molten metal injection passage 26 has a circular cross-sectional shape. It is preferable that the thickness g of the joint portion 27 sandwiched between adjacent molten metal injection passages 26 be as small as possible to ensure strength, and that the passage area of each molten metal injection passage 26 be made larger.

That is, in the mold device 13, the flange portion 23 of the core 20 is fitted and fixed to the core holding inner diameter portion 21 of the mold 19, and the molten metal injection passage 26 and the tube forming passage z5 are communicated in a straight manner. 28 in FIG. 2 is a fixing bottle for the mold 19 and the core 20.

In addition, #JP molding Zt 13 specifically refers to mold 19.
A copper water-cooling jacket body 30 is fitted to the molten metal outflow side end of the mold 19 via a copper liner 29, and a brick inlet 3 is fitted to the molten metal flow side end of the mold 19.
1.32 is fitted, and an iron plate 33 is fitted between the water-cooled jacket body 30 and the insert ring 31. As a result, the mold device 13
The part 0 is a cooling part for solidifying the molten metal, the part of the insert ring 31 is a non-cooling part, and the part of the insert ring 3 is a non-cooling part.
The part 2 is used as the attachment part of the holding furnace 11 to the furnace 1nllA.

Further, the continuous casting apparatus 10 of this embodiment has a mold apparatus 13.
To prevent the molten metal flowing into the core from being supercooled,
A thank-you note 20A is provided at the molten metal inflow side end of the mold 1, and the end of the mold device 13 protrudes into the furnace.

Therefore, the continuous casting apparatus 10 includes a temperature measuring device 41,
It has a control device 42.

The temperature measuring device 41 includes a plurality of temperature sensors 43 i (i=1
-n), and the mold outlet temperature T1. And the average temperature T2 of the casting tube 14 between the mold exit and the drawing roller device 16 is measured. The measurement results of the temperature measuring device 41 are transferred to the control section 2!42.

As shown in FIGS. 4 and 5, the control device 42 controls the casting pipe 1.
4, ■ Constant drawing speed (Ve) during drawing time (t e)
), it is pulled out by the pulling length P, ■ it stops for the above waiting time (tw) after pulling out, and ■ it stops! The pushing time (t
During r), the hydraulic pump drive control unit of the drawing roller device 16 is pressed at a constant pushing speed (Vr) by a length A or more corresponding to the amount of heat shrinkage of the casting tube 14 from the mold device 13 to the drawing roller device 16. 44. In addition, cast pipe 1
The drawing speed of No. 4 is fed back to the control device 42 via a drawing speed detector 45 connected to the output shaft of the hydraulic motor 16B.

Here, the control device 42 controls the measurement results TI and T2 of the temperature measuring device 41, the distance between the outlet of the mold device 13 and the drawing roller device 16, and the casting tube 14.
Based on the coefficient of linear expansion α, the above A is calculated as follows: A=L·αo (Tl−T2) −(1).

Next, the operation of the above embodiment will be explained.

According to the embodiment described above, a length longer than the amount of solid shrinkage of the casting tube 14 when the drawing is stopped is pushed into the mold device 13 after the drawing is stopped. Therefore, even if cracks occur in the solidified slab in the mold, the cracks will be repaired and resolved under the above-mentioned pushing action, and as a result, no cracks will occur on the surface of the cast tube 14 after pultrusion casting is completed. There is nothing to do with it.

In addition, the control device 42 performs the pushing control as described above after accurately calculating the length A corresponding to the solid shrinkage amount of the casting tube 14 at the time of stopping drawing using the above-mentioned formula (1). , the occurrence of cracks can be reliably prevented.

[Effects of the Invention] As described above, according to the present invention, a cast pipe can be stably drawn and cast without causing cracks on its surface.

[Brief explanation of the drawing]

FIG. 1 is a control system diagram showing one embodiment of the present invention. Fig. 2 is a sectional view showing the mold device, Fig. 3 is an end view showing the mold equipment, Fig. 4 is a schematic diagram showing the intermittent drawing operation of the present invention, and Fig. 5 is a diagram showing the intermittent drawing operation of the present invention. It is a speed diagram. 10... Continuous casting device. DESCRIPTION OF SYMBOLS 11... Molten metal holding furnace, 12... Casting port, 13... Mold device, 14... Casting pipe, 16... Drawing roller device (drawing device), 41...
-Temperature measuring device, 42...control device. Agent Patent Attorney Osamu Shiokawa Figure 2 Figure 4

Claims (2)

[Claims] (1) In a continuous casting method for metal tubes, the molten metal contained in the molten metal holding furnace is solidified into a tubular shape using a molding device to form a cast tube, and the cast tube is pulled out using a drawing device. Thinning out, stopping during the waiting time after this drawing, and during the pushing time after this stop, pushing the casting pipe to a length corresponding to the amount of heat shrinkage from the mold device to the drawing device.
A continuous casting method for metal tubes characterized by repeating the process as one cycle. (2) It has a mold device that is disposed at the pouring port of the molten metal holding furnace and solidifies the molten metal into a tubular shape to form a cast tube, and a drawing device that pulls out the cast tube formed by the mold device. In the continuous metal tube casting apparatus, the mold outlet temperature T1 of the casting tube is
and a temperature measuring device for measuring the average temperature T2 between the mold outlet and the drawing device; the casting tube is pulled out during the drawing time, stopped during the waiting time after this drawing, and during the pushing time after this stop. , and a control device that controls the drawing so that one cycle is repeated by pushing the cast tube by a length A corresponding to the amount of heat shrinkage from the mold device to the drawing device, and the control device controls the drawing at the above temperature. T which is the measurement result of the measuring device
1 and T2, the distance L between the mold outlet and the drawing device, and the coefficient of linear expansion α of the casting tube, the above A can be calculated as A=L・
A continuous casting apparatus for metal tubes, characterized in that it is configured to calculate α·(T1-T2).