JPH0225245A - Casting mold device for horizontal continuous casting device for metallic pipe - Google Patents

Abstract

PURPOSE:To produce a cast pipe which allows stable drawing and has good dimensional accuracy by forming the outside diameter part which forms the pipe inside surface of a core to a tapered shape toward the outlet side of a casting mold and setting the grade of the front surface of the outside diameter part which forms the pipe inside surface to the grade smaller than the grade of the rear surface thereof. CONSTITUTION:The grade alpha of the front surface of the outside diameter part 24 which forms the pipe inside surface of the core 20 is previously set smaller than the grade betaof the rear surface thereof. As a result, the spacing between the inside diameter part 22 which forms the pipe outside surface of a casting mold 19 and the outside diameter part 24 of the core 20 is equaled at the time of horizontal continuous casting when the weight of the cast pipe 14 acts. Namely, the outside diameter part 24 is tapered and, therefore, the cast pipe 14 can be stably drawn without strongly embracing the core 20. The spacing between the core 20 and the casting mold 19 is equalized uniformly in the peripheral direction of the pipe and the cast pipe 14 having the good dimensional accuracy without having eccentricity and unequal thickness is produced. the grades alpha, beta are changed in a 1/50-1/300 range.

Description

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

[Prior art] Regarding the horizontal continuous casting method of metal tubes, Japanese Patent Application Laid-open No. 80-5
As described in Japanese Patent No. 4255, a mold device is used which includes a mold having an inner diameter portion for forming the outer surface of the tube, and a core disposed within the mold and having an outer diameter portion for forming the inner surface of the tube. That is, the above-mentioned molding device is disposed at the pouring port of a molten metal holding furnace, the molten metal is cooled in this molding device to form a cast tube, and this casting tube is pulled out horizontally.

[Problem to be Solved by the Invention III] By the way, during the above-mentioned horizontal continuous casting, the molten metal in the mold solidifies and shrinks greatly around the core and is drawn out to form a cast ia pipe. Therefore, in order to prevent the cast tube, which has solidified and shrunk significantly, from strongly enclosing the core and resulting in failure to pull it out,
As schematically shown in FIG. 8, it is conceivable that the outer diameter portion of the tube inner surface of the core is tapered toward the exit side of the mold. In FIG. 8, 1 is a mold, 2 is a core, 3 is a molten metal injection passage, 4 is a tube forming passage, and θ is the slope of the surface of the outside diameter portion of the inner surface of the tube.

Only 1. Therefore, regarding the cast iron pipe (65A) cast using the molding device shown in Fig. 8, the amount of 12 yen is as shown in Fig. 6.
As a result of dividing it into equal parts and measuring the inner and outer diameters and wall thickness of each part, Fig. 7 was obtained regarding the wall thickness at each pulling length position. According to this FIG. 7, the upper surface side of the tube (
There is an uneven thickness in that the wall thickness of tubes No. 1.2, 3.11゜12) is thick, and the inner surface of the tube lower surface side (No. 5.8, 7, 8.9) is thinner. It was also observed that the center of the tube was eccentric downwards with respect to the horizontal plane including the tube axis.

An object of the present invention is to make it possible to stably draw a metal tube and to manufacture a cast tube with good dimensional accuracy when horizontally continuously casting a metal tube.

[Means for Solving the Problems] The present invention has a mold having an inner diameter portion for forming the outer surface of a tube, and a core disposed in the mold and having an outer diameter portion for forming the inner surface of the tube, and is suitable for use in casting of a molten metal holding furnace. In a mold device for horizontal continuous casting of metal tubes, which is installed at the inlet and cools the molten metal to form a cast tube, which can then be pulled out horizontally, the outer diameter of the inner tube molding of the core is connected to the mold. The pipe is tapered toward the exit side, and the slope of the upper surface of the outer diameter portion formed on the inner surface of the tube is smaller than the slope of the lower surface thereof.

[Function] According to the inventor's study, the reason why the above-mentioned eccentric wall thickness was observed in the obtained cast tube when the above-mentioned mold apparatus shown in FIG. 8 was used is due to the casting action acting on the core. The tube's own weight pushes and bends the core downward, and the gap between the inner diameter part of the mold for forming the outer tube surface and the outer diameter part for forming the inner tube surface of the core is uneven in the tube circumferential direction (the gap on the top side of the tube is large, and the gap on the bottom side of the tube is uneven). The gap is small).

However, in the present invention, by setting the slope of the upper surface of the outer diameter portion of the inner tube inner surface of the core to be smaller than the slope of the lower surface, the inner diameter portion of the tube outer surface of the mold and the inner diameter portion of the core The gap with the outer diameter part of the surface molding can be made equal during horizontal continuous casting where the weight of the casting tube acts.

That is, according to one aspect of the present invention, since the outer diameter portion of the core formed on the inner surface of the tube is tapered, the cast tube can be stably drawn out without strongly enclosing the core. Furthermore, the gap between the core and the mold during casting can be equalized in the tube circumferential direction, and a cast tube with good dimensional accuracy without eccentric thickness can be manufactured.

[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, Fig. 3 is an end view showing the mold device, Fig. 4 is a sectional view schematically showing the characteristic configuration of the mold device, and Fig. 5 is a side view of Fig. 4. It is.

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 10 includes a mold equipment 31
13 to cool the molten metal to form a cast pipe 14, which is then pulled out horizontally! ! to cast.

The continuous casting device 10 has a casting tube 1 at the exit side of the mold device 13.
4 and a drawing roller device 1B for drawing out the cast pipe 14. The pulling roller device M16 consists of a pinch roller 17 and a press roller 18. In addition, the pull-out roller W16
is a hydraulic motor 16 driven by a hydraulic pump 16A.
B, and this hydraulic motor 16B operates a pinch roller.
17 to apply a pulling force to the cast tube 14 as a result.

As shown in FIGS. 2 and 3, the mold assembly 2t13 includes a mold 19 made of graphite and a core 20 also 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 inflow side, and a tube outer surface forming inner diameter part 22 around the mold center axis 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. . The core 20 also includes molten metal injection passages 26 communicating with the tube forming passage 25 at each of a plurality of positions (fourth position 71 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.

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 25 are communicated in a straight manner. Reference numeral 28 in FIG. 2 is a fixing pin between 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, the mold device 13 has a cooling section for solidifying the molten metal in the water-cooled jacket body 30, and an insert ring 31.
A portion of the insert ring 32 is a non-cooled portion, and a portion of the insert ring 32 is a portion that is attached to the furnace wall 11A of the holding furnace 11.

Further, the continuous casting apparatus 210 of this embodiment has a mold 211
In order to prevent the molten metal flowing into the core 3 from being overcooled, a thank-you slot 20A is provided at the end of the molten metal inflow side of the core 20, and the end of the mold device 13 is made to protrude into the furnace.

Note that the continuous casting apparatus 110 includes a control device 41. The control device 41 controls the casting tube 14 according to the drawing time (t
The hydraulic pump drive control of the drawing roller unit W16 is carried out in order to pull out by the drawing length P at a constant drawing speed (We) during e), and return to green as one cycle is the opening and stopping of the waiting time (tw) after the above-mentioned drawing. 42. The drawing speed of the cast pipe 14 is controlled by the control unit via a drawing speed detector 43 connected to the output shaft of the hydraulic motor 16B.
41.

In the molding device 13, as shown in FIGS. 4 and 5, the tube inner surface molding outer diameter portion 24 of the core 20 is
It is set to form a tapered shape that tapers toward the exit side.

In addition, in the mold device 113, the center of the distal end of the outer diameter portion 24 for forming the inner surface of the tube is eccentrically e towards the t side with respect to the center of the base end thereof, and the upper surface of the outer diameter portion 24 for forming the inner surface of the tube (with respect to the horizontal ) The slope α is set to be smaller than the slope β of the lower surface. The slope γ of the side surface of the outer diameter portion 24 formed on the inner surface of the tube is α
and β.

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

In the above embodiment, the tube inner surface molded outer diameter portion 3 of the core 20
By setting the slope α of the upper surface of the mold 19 to be smaller than the slope β of the lower surface of the mold 19, the inner diameter portion 2 of the mold 19 is formed.
2 and the tube inner molded outer diameter portion 24 of the core 20,
The same can be achieved during horizontal continuous casting where the weight of the casting tube 14 acts.

That is, according to the above-mentioned embodiment, since the tube inner surface molded outer diameter portion 24 of the core 20 is tapered, the T4 tube making 14 can stably pull out the core 20 without strongly holding it. Further, the gap between the core 20 and the mold 19 during casting can be equalized in the tube circumferential direction, and a cast tube 14 with good dimensional accuracy without eccentric thickness can be manufactured.

According to the inventor's study, the above-mentioned gradients α and β in the outer diameter portion 24 of the tube inner surface molding of the core 20 are 1150~
It is best to vary it within a range of 1/300.

The reasons for limiting the numerical values of the gradients α and β are as follows.

In other words, this gradient has a very strong relationship with the type of cast metal and the casting speed, and determines whether or not continuous casting operations for cast pipes are possible.

The operational results that are the basis for setting the slope range of the present invention will be explained.

When a 30A cast iron pipe was drawn using the core 20 of the gradient machine/300 at a casting speed of about 500 m5/min, the operation was very stable. On the other hand, the core 2 of the gradient device 740G
As a result of carrying out the operation using 0, the core 20 became a tight fit and could not be pulled out.

Further, when an 80A cast iron pipe was drawn at a casting speed of approximately 5005 w/min using a gradient machine/+00 core 20, stable operation was possible.

Although the above operational results are for cast iron, it is easy to imagine that the slope can be made even larger for metals that have high thermal conductivity and large thermal contraction.

According to the experimental results of the present inventor, when casting a cast iron pipe 65A (wall thickness 4.2 to 4.5 1), the conventional thickness unevenness ratio of 11
．． 5% could be improved to 4.8% by applying the present invention.

[Effects of the Invention] As described above, according to the present invention, when performing horizontal continuous casting of a metal tube, it is possible to manufacture a cast tube that can be drawn stably and has good one-dimensional accuracy.

[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 device, Fig. 4 is a sectional view schematically showing the characteristic configuration of the mold device, and Fig. 5 is a side view of Fig. 4. , FIG. 6 is a sectional view showing a casting tube, FIG. 7 is a line diagram showing the wall thickness distribution of the casting tube, and FIG. 8 is a sectional view schematically showing a conventional molding device. lO... Continuous casting device, 11... Molten metal holding furnace 12... Casting port, 13... Mold device, 14... Casting tube 19... Mold, 20... Core, 22 . . . Tube outer surface molded inner diameter portion 24 . . . Tube inner surface molded outer diameter portion. Agent Patent Attorney Osamu Shiokawa Figure 2 Figure 1 Figure 7

Claims (1)

[Claims] (1) It has a mold with an inner diameter part for forming the outer surface of the tube, and a core disposed in the mold and having an outer diameter part for forming the inner surface of the tube, and is disposed at the pouring port of the molten metal holding furnace to cool the molten metal. In a mold device for horizontal continuous casting of metal pipes, which forms a cast pipe and allows the cast pipe to be pulled out horizontally, the outer diameter part of the molded inside of the pipe of the core tapers toward the exit side of the mold. 1. A mold device for horizontal continuous casting of metal tubes, characterized in that the slope of the upper surface of the outer diameter portion of the inner surface of the tube is smaller than the slope of the lower surface thereof.