JPH0225243A - Horizontal continuous casting method for metallic pipe - Google Patents

Abstract

PURPOSE:To execute horizontal continuous casting of the metallic pipe which is free from breakout, failure in drawing, etc., by increasing the temp. of a molten metal in accordance with the predetermined temp. regulation rate of the molten metal to maintain the adequate fluid state of the molten metal in a casting mold, thereby obviating the degradation in the flowability of the molten metal by a drop of a molten metal head. CONSTITUTION:The molten metal in a molten metal holding furnace 11 for continuous casting decreases gradually and the head of the molten metal decreases when the molten metal is poured into the casting mold 13. The temp. of the molten metal is increased in accordance with the predetermined temp. regulation rate of the molten metal in order to compensate the degradation in the flowability by the drop of the molten metal head. The flowability of the molten metal in the casting mold 13 is optimized in this way and the degree of the shrinkage of the ingot in the casting mold 13 on solidification is made adequate. The stable drawing state is thus maintained. The smooth insertion of the molten metal into the space formed between the front surface of the casting mold and the front surface of the cast pipe is possible if said space is generated by the influence of the gravity acting on the cast pipe 11 in the casting mold 13. The generation of a blowhole defect which is liable to arise stop the cast pipe is, therefore, averted.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for horizontal continuous casting of metal tubes.

[Prior art] Regarding the Mizumo Sho BL casting method for metal tubes, there is
As described in Publication No. 54255, 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 #pI pipe, and this cast pipe is pulled out by a drawing device. Cast I precious.

By the way, in the horizontal continuous casting method for metal tubes as described in L, it is necessary to appropriately set the flow state of the molten metal in the mold to ensure a stable drawing state of the NIA tube.

[Problems to be Solved by the Invention] However, in the conventional horizontal continuous casting of metal tubes, the fluidity fE of the molten metal in the mold described in L is adjusted to an appropriate level of 6.
It is difficult to make decisions, resulting in the following inconveniences.

(2) If the fluidity of the molten metal in the mold is too good, a solidified shell will not be formed sufficiently in the mold, resulting in breakout.

(2) If the fluidity of the molten metal in the mold is poor, the solidification and shrinkage of the slab in the mold will be large enough to make it impossible to pull it out. Also,
When a gap is created between the top surface of the mold and the top surface of the casting tube due to the influence of gravity acting on the casting tube in the mold, the molten metal is inserted into this gap, causing deep scratches and holes, especially on the top surface of the casting tube. There is a risk that this may occur.

Incidentally, the above-mentioned problems (1) and (2) become more pronounced as the metal tube becomes thinner.

The present invention maintains an appropriate fluidity state of the molten metal in the mold when horizontally continuously casting a cast pipe, and prevents breakout and
The purpose is to stably perform pultrusion casting without being unable to pull out or causing casting defects.

[! Means for Solving II] The present invention according to claim 1 solidifies the molten metal contained in the molten metal holding furnace into a tubular shape in a g-type device to form a cast pipe, and then draws the cast pipe by drawing it. In the horizontal continuous casting method for horizontally drawn metal pipes, [phase] the initial head and initial temperature of the molten metal in the holding furnace necessary to ensure stable operation, and ■ the mold temperature as the head of the molten metal in the holding furnace decreases. The water temperature per unit head required to compensate for changes in the fluidity of the molten metal in the 31! The rate is determined in advance, and the molten metal is
Load the holding furnace into the holding furnace at the initial head and initial melt temperature, and then as the operation progresses, the hot water temperature and molten metal head in the holding furnace are detected, and the detected molten metal head drop amount and the hot water temperature adjustment described in (■) above are carried out. The hot water temperature adjustment amount is calculated based on the water temperature adjustment amount, and the hot water temperature is adjusted based on this hot water temperature adjustment amount.

The present invention according to claim 2 provides that when the cast metal is cast iron,
The hot water temperature adjustment rate per unit head is [2 (1 to 30℃)
This is a 7700m layer head J.

[Function] As a result of studying horizontal continuous casting of metal tubes, the present inventor found that ``the molten metal head in the molten metal holding furnace and the molten metal temperature affect the fluidity of the molten metal in the mold'' and ``the molten metal head decreases as the molten metal head decreases.'' The present invention was made for the first time based on this knowledge, and has the following effects.

■First, at the start of operation, the initial head and initial temperature of the molten metal charged into the holding furnace are determined by the shape of the holding furnace.

The optimum state is set in advance depending on the mold shape, cast metal, etc. As a result, the fluidity of the molten metal within the mold is also optimized, and stable drawing of the cast pipe is started.

(When the molten metal in the holding furnace is injected into the mold and gradually decreases, and the head of the molten metal decreases, the pushing pressure applied to the molten metal in the mold decreases, and the fluidity of the molten metal in the mold deteriorates.) However, in the present invention, the hot water temperature is raised at a predetermined hot water temperature adjustment rate so as to compensate for the deterioration in fluidity due to the drop in the molten metal head.

The fluidity of the molten metal in the mold becomes appropriate, and the degree of solidification and shrinkage of the slab in the mold is optimized to form a stable drawn shape. Additionally, when a gap is created between the top surface of the mold and the top surface of the casting tube due to the influence of gravity acting on the casting tube within the mold, the molten metal is inserted smoothly into this gap, thereby eliminating deep scratches that tend to occur on the top surface of the casting tube. , avoiding the occurrence of hole defects.

According to the inventor's experimental results, when the cast metal is cast iron, the above-mentioned hot water temperature adjustment rate per unit head is [2
0 to b are suitable. In other words, if the temperature is raised to exceed ■[30℃7700■■head], the water temperature will become excessively high;
As a result, it was found that the fluidity of the molten metal within mold i4 became excessively good, and a solidified shell was not sufficiently generated within the mold, making breakout likely to occur. Also, ■[
20° C./700 mg + head], the temperature of the molten metal is insufficiently raised, and as a result, the fluidity of the molten metal in the mold is poor.

It was observed that the solidification shrinkage of the slab in the mold was large, resulting in poor drawing, and the formation of deep flaws and four-hole defects on the upper surface of the cast tube.

That is, according to the present invention, when continuously horizontally casting a casting pipe, the flow state of the molten metal in the mold is maintained at an appropriate level,
Stable pultrusion casting is possible without breakouts, inability to pull out, or casting defects.

[Example] FIG. 1 is a control system diagram showing one embodiment of the present invention.

FIG. 2 is a sectional view showing the mold device, and FIG. 3 is an end view showing the mold device.

As shown in FIG. 1, the continuous casting apparatus 10 includes a molten metal holding furnace 1.
The 0M follow-on casting apparatus 1O is equipped with a mold device 13 attached to a pouring port 12 formed at the lower side of the mold device M1.
3, the molten metal is cooled to form a casting tube 14, which is horizontally drawn and cast.

The continuous casting equipment atto has a heating equipment Htt in the molten metal holding furnace 11.
At-equipped, the water temperature can be adjusted.

Continuous casting? i, the device 1O is equipped with a guide roller 15 that supports the casting tube 14 on the exit side of the molding device f13, and also includes a drawing roller 11 for pulling out the casting tube 14; i
611n L, pullout low 5-'ei! ! 16 consists of a pinch roller 17 and a press roller 18. Note that the drawing roller device W116 has a hydraulic motor 16B driven by a hydraulic pump 16A, and this hydraulic motor 16B drives a pinch roller 17 to apply a drawing force to the cast pipe 14. There is.

As shown in FIGS. 2 and 3, the mold assembly 2113 includes a mold 19 made of graphite and a core 20 made of graphite.

The mold 19 has a hollow shape and includes a core holding inner diameter part 21 at the end on the molten metal flow side, and a core holding inner diameter part 2! An inner diameter portion 22 for molding the outer surface of the tube is provided around the center axis of the mold over substantially the entire length except for.

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 molten metal flow side end.
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. . The core 20 also includes molten metal injection passages 26 that communicate with the tube forming passage 25 at each of a plurality of positions (four positions in this embodiment) around the mold center axis in the flange portion 23 . Each molten metal injection passage 26 has a cross-sectional shape of an arc. 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.

In other words, the mold′! In the 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 25 are communicated in a straight manner. 28 in FIG. 2 is a fixing bottle for the mold 19 and the core 20.

Specifically, the mold device 13 is configured to fit a water cooling jacket body 30 made of copper to the end of the mold 19 on the outflow side of the molten metal via a copper liner 29, and to fit a water cooling jacket body 30 made of copper to the end of the mold 19 on the inflow side of the molten metal from a brick. The insert rings 31 and 32 are fitted, and the water cooling jacket body 30 and the insert ring 31 are fitted.
An iron plate 33 is fitted in between. As a result, casting J! The I device 13 uses the water-cooled jacket body 30 as a cooling part for solidifying the molten metal, the insert ring 31 as a non-cooling part, and the insert ring 32 as a mounting part on the furnace wall 11B of the holding furnace 11. There is.

Further, the continuous casting apparatus to of this embodiment has a mold apparatus 13.
In order to prevent the molten metal incorporated into the core from becoming overcooled,
A thank-you slot 20A is provided at the molten metal inflow side end of the mold assembly 13, and the end of the mold assembly al13 is made to protrude into the furnace.

Thus, the continuous casting apparatus 10 includes a control device 41, a hot water temperature measuring device 42, and a drawing length measuring device 43.

The control device 41 controls the casting tube 14 according to ■drawing time (t e)
The drawing roller device 511
The hydraulic pump drive control unit 44 of No. 8 is controlled. The drawing speed of the cast tube 14 is fed back to the control device 41 via a drawing speed detector 45 connected to the output shaft of the hydraulic motor 16B.

The hot water temperature measurement device 42 measures the hot water temperature in the molten metal holding furnace 11 and transfers the measurement result to the control device 41.

The drawn length measuring device fi43 measures the drawn length of the cast pipe 14 pulled out from the mold device 113, and transfers this measurement result to the control device 41. The control device 41 obtains the measurement results of the drawing length measuring device M43 and determines the initial head of the molten metal loaded in the holding furnace 11 and the subsequent head of the holding furnace 11 as the operation progresses.
Based on the amount of molten metal drawn out as the casting pipe 14,
The amount of molten metal in the holding furnace 11 at the current time is calculated.

Therefore, the control device 141 controls (1) the initial head and initial temperature of the molten metal in the holding furnace 11 necessary to ensure stable operation, and (2) the fluidity of the molten metal in the mold 19 as the head of the molten metal in the holding furnace 11 decreases. The hot water temperature adjustment rate per unit head necessary to compensate for changes is stored in advance. The above data (■) is mainly determined by the holding furnace shape, mold shape, cast metal, etc., and the @ data is mainly determined by the mold shape, cast metal, etc.

Therefore, the casting operation using the above-mentioned continuous casting apparatus MlO is performed as follows.

(2) The molten metal is loaded into the holding furnace 11 at the initial head and initial temperature of (2) above, and the operation is started.

During the subsequent operation of the control device W141, the control device W141 performs the
The molten metal head of the holding furnace 11 is detected by the operation, and the amount of hot water temperature adjustment is calculated based on the detected amount of drop in the molten metal head and the hot water temperature adjustment rate of (2) above. Furthermore, the control device 2141 drives and controls the heating device 22t IA based on this hot water temperature adjustment amount,
The hot water temperature in the holding furnace 11 measured by the hot water temperature measurement device R42 is adjusted.

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

(1) First, at the start of operation, the initial head and initial temperature of the molten metal charged into the holding furnace 11 are set to optimal conditions predetermined by the holding furnace shape, mold shape, cast metal, etc.

As a result, the fluidity of the molten metal within the mold is also optimized, and stable drawing of the cast tube 14 is started.

■The molten metal in the holding furnace 11 is poured into the mold and gradually decreases.
Generally when the head of molten metal drops.

It is thought that the pushing pressure applied to the molten metal in the mold decreases, and the fluidity of the molten metal in the mold deteriorates. However, in the above embodiment, the temperature of the hot water is raised at a predetermined hot water temperature adjustment rate to compensate for the deterioration in fluidity due to the drop in the molten metal head. As a result, the fluidity of the molten metal within the mold is moderate.

The degree of solidification and shrinkage of the slab in the mold is optimized to create a stable drawing state. Additionally, when a gap is created between the top surface of the mold and the top surface of the casting tube due to the influence of gravity acting on the casting tube within the mold, the molten metal is inserted smoothly into this gap, thereby eliminating deep scratches that tend to occur on the top surface of the casting tube. , avoiding the occurrence of hole defects.

In addition, when the metal to be cast by the above 1M continuous casting equipment 1O is cast iron, the 1M continuous casting equipment 1O is used! As mentioned above, the hot water temperature adjustment rate per unit head set to 141 is [20~30℃77
00 Seihou Head].

(2) - Recorded hot water temperature Jilti rate [20~b] is supported by the data in Table 1, which is the research result of the present inventor. That is, in Experiment Nos. 1 to 9 in which the hot water temperature adjustment rate was within the above range, the castability and quality of the metal tubes were good. On the other hand, if the hot water temperature adjustment rate is outside the above range, experiment No. 10 outside the upper limit.
For No. 11.14, a breakout occurred, and for Experiment No. 12.13.15 and No. 16.17, which were outside the lower limit, the mold could not be pulled out due to anti-solidification, and deep flaws and perforation defects occurred on the upper surface of the PI tube.

Hereinafter, specific implementation results of the present invention will be explained.

By the method of the present invention described in L, thin-walled cast iron pipes (32A, 65A, 80A) with a wall thickness of 4.2 to 4.5 mm are connected! Cast. As a result, it was found that the number of breakouts, which was 3/10 charges under the conventional law, could be changed to 0/10 charges, thus confirming the effectiveness of the present invention.

In carrying out the present invention, the molten metal head in the holding furnace may be directly detected by a float inserted into the holding furnace, a level meter provided on the outer surface of the holding furnace, or the like.

Furthermore, the present invention has substantially similar effects not only in continuous casting of cast iron but also in continuous casting of other metals.

[Effects of the Invention] As described above, according to the present invention, when performing horizontal continuous casting of a cast pipe, the moving state of the molten metal in the mold is maintained at an appropriate level, and breakout 2 cannot be pulled out or casting defects occur. , stable pultrusion casting is possible.

[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, and FIG. 3 is an end view showing the mold device. 10... Continuous casting device. 11... Molten metal holding furnace. 11A... Heating device, 13... Mold device, 14... Casting pipe, 41... Control device, 42... Hot water temperature measuring device, 43... Drawing length measuring device (molten metal spatula)

Claims (2)

[Claims] (1) In the horizontal 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 horizontally pulled out using a drawing device.
a) The initial head and temperature of the molten metal in the holding furnace necessary to ensure stable operation, and (b) To compensate for changes in the fluidity of the molten metal in the mold due to the drop in the head of the molten metal in the holding furnace. The necessary hot water temperature adjustment rate per unit head is determined in advance, molten metal is loaded into the holding furnace at the initial head and initial hot water temperature as described in (a) above, and as the operation progresses thereafter, the hot water temperature in the holding furnace is adjusted. The molten metal head is detected, a hot water temperature adjustment amount is calculated based on the detected molten metal head drop amount and the hot water temperature adjustment rate in (b) above, and the hot water temperature is adjusted based on this hot water temperature adjustment amount. Horizontal continuous casting method for metal tubes. (2) The horizontal continuous casting method for metal pipes according to claim 1, wherein when the casting metal is cast iron, the hot water temperature adjustment rate per unit head is [20 to 30°C/700 mm head].