JPH04200845A - Adjustable mold - Google Patents

Abstract

PURPOSE:To uniformly cool a cast billet while shifting according to solidified shrinkage and to obtain the cast billet having good quality by adjusting an inner diameter size with a positional adjusting device disposed at the inlet of an adjustable mold and making an outlet shiftable in a radius direction with a hydraulic cylinder. CONSTITUTION:The inner diameter size of molds is adjusted and fixed with screws 18 in the positional adjusting device disposed at the inlet of adjustable molds 4a, 4b divided into four elements in the radius direction of a casting cross section following to a cylindrical mold 2 in a continuous casting device tightly connecting a tundish 1 and the cylindrical mold 2. Successively, by making the outlet of adjustable molds 4a, 4b shiftable to the radius direction of casting cross section with the hydraulic cylinder 13 disposed in the radius direction of casting cross section, the cast billet comes into contact with each element and uniformly cooled and the cast billet having good quality can be obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mold for continuous casting of metal such as steel, in which the supplied molten metal is cooled and solidified to form a U7 slab. In particular, the present invention relates to an adjustable mold for continuous casting equipment that can uniformly cool slabs.

[Prior art and background] Continuous casting involves supplying 1,000 liters of molten metal stored in a tundish. here/? iJ1+1
Then, at least the outer peripheral part is solidified to form a slab 7, and the slab is continuously pulled out using a pulling device installed on the flow side of the mold 1. The mold F is made by statically forming a mold into a cylindrical body 7, and cooling its outer peripheral wall (often water cooling).Thus, the molten metal supplied to the hollow part 92 is solidified. The mold is made of a thermally conductive old material with a hollow part corresponding to the desired cross-sectional shape and size of the slab, and a 7'n jJI is placed on the outside of the mold. A water jugient is installed and the structure is such that cooling water flows along the outside wall of the mold.Therefore, the molten metal loses its heat to the cooling water and cools and solidifies. It becomes a slab.

The casting direction (the axial direction of the mold) of continuous casting performed in this way is not limited to vertical, but may be set horizontally or in an inclined direction, and the cross section of the hollow section can also vary widely, such as rectangular, polygonal, circular, etc. .

When this mold is classified according to its form, it is divided into two types as explained below.

(a) Mold with an integrally formed cylindrical body There is a so-called tubular mold in which the mold is an integral cylinder or square tube to obtain a small cross-section billet, and a rectangular billet with a large cross-section. There is a so-called assembled mold in which multiple mold elements divided in the circumferential direction are closely assembled to form a cylindrical body to obtain a slab or bloom, but in all cases the inner circumferential wall of the hollow part is continuous. It has a closed cross section, and is used as a fixed mold in which the cross-sectional dimension of the hollow part does not change during casting.

As the slab solidifies and cools, it contracts and its cross-sectional dimension becomes smaller, so in a mold with such an integrally formed cylindrical body, in order to maintain contact between the mold and the slab,
An appropriate taper is formed on the inner circumferential wall of the mold so that the downstream side has a smaller dimension. However, since the shrinkage rate of a slab varies depending on many factors such as the type of metal to be cast, the casting temperature, and the casting withdrawal speed, it is not possible to simply taper the inner peripheral wall of the mold and the surface of the slab. It is difficult to maintain uniform contact with the mold, so in order to overcome this drawback, this fixed mold is often shortened and a movable mold (adjustable mold), which will be described below, is installed on the downstream side.

(b) A mold in which a cylindrical body is formed by a plurality of mutually separate and independent mold elements A mold in which a plurality of mutually separate and independent elements movable in the radial direction are arranged in a cylindrical shape, and is called an adjustable mold. It is used as a movable mold in which the cross-sectional dimension of the hollow part changes during casting.

The elements of this adjustable mold are arranged apart from each other in the circumferential direction without being in close contact with each other, and are pressed against the surface of the slab by force means such as a spring or a hydraulic cylinder.

In order to make this movement possible, each element of the adjustable mold has a gap, so it is necessary to create a gap after a suitable solidified layer has been formed on the surface of the molten metal, that is, downstream of the fixed mold. It will be done.

As mentioned above, the slab shrinks as it cools and solidifies, but with this adjustable mold, each mold element is pressed against the slab surface, so there is good contact with the slab surface, and the fixed mold In comparison, it becomes possible to cool the slab more uniformly.

As a combination of these fixed molds and movable molds,
In Japanese Patent Publication No. 61-32104 (hereinafter referred to as "prior art"), as shown in Figures 5 and 6, "1
mold part 41 (corresponding to a fixed mold), and a second mold part 42, 43 (corresponding to a fixed mold) located downstream of the first mold part 41.
The second mold part has a wall part 44 (corresponding to a cooling plate) divided into four parts in the circumferential direction of the casting cross section, and this wall part 44 is installed in a direction parallel to the casting direction. The adjustment device 45 (double-acting hydraulic cylinder) is configured to be movable in the radial direction of the casting section.
However, the wall portion 44 is controlled by a bell crank 46 which changes the direction of movement of the adjusting device 45 parallel to the casting direction into a direction approximately perpendicular to the casting direction (corresponding to the radial direction of the casting section).
An invention relating to a continuous casting mold characterized in that the mold is connected to an inflow portion 47 and an outflow portion 48 of the invention is disclosed.

[Problem to be solved by the invention]

However, when continuous casting is performed using a conventional continuous casting mold, there are the following drawbacks. In other words, the cooling of the slab progresses unevenly, making it easy for the slab to deform and crack.
The problem is that the operation of the hellcrank mechanism cannot be fully reliable.

1) Occurrence of deformation and cracking of slab ■ The taper provided in the hollow part of the fixed mold is determined in advance for each metal to be cast based on careful calculations and experiments. If the taper of the mold is larger than the shrunk mold of the slab, it will not be possible to pull out the slab smoothly, and conversely, if the taper is small, there will be a gap between the slab and the top of the mold. This is because heat transfer is hindered and the cooling of the slab stops progressing.

However, when continuous casting is actually performed, the slab tends to shrink along the taper of the mold. In other words, the shrinkage rate of a slab changes depending on the casting (drawing) speed and the temperature of the molten metal, so even if the type (component) of the cast metal is the same, the shrinkage rate will change each time or during casting. changes over time. As a result, as the slab cools and solidifies, it rarely shrinks in a manner similar to its original cross-section, and in most cases, the circular cross-section deforms into an oval5, or the rectangular cross-section 1fIi becomes nearly diamond-shaped. do.

As noted in 1, heat transfer is hindered when a gap is formed between the surface of the slab and the mold, so if the slab deforms and comes into contact with the mold unevenly as described in 2, the contact area There is a large deviation L1 in the cooling strength from the part where there is a gap.
(Since the slab is shrunk in such a way as to promote the above deformation, uneven cooling and deformation will first proceed before the slab leaves the mold. As a result, the inside G of the slab will be uneven or asymmetrical. A solidified structure may be formed or cracks may occur.

Adjustable molds, which press mold elements onto the surface of a slab, are made by shortening the fixed mold and connecting it to the flow of the slab in order to prevent partial cooling and deformation of the slab. According to the technology's continuous casting mold, the pressing force of the adjustable mold in the direction of the spinning cross section is not controlled, so the wall portion 44 (cooling plate) of the mold against which the slab ζ1 is pressed has a low strength. The weak part, that is,
It tends to hit unevenly on the casting J~ part (the part near the fixed mold) where the solidified layer on the surface of the molten metal is thin, and as a result, cooling becomes uneven and the slab becomes easily deformed.

In this case, if the length of the first mold part 41 (fixed mold) is short, the thickness of the solidified layer on the surface of the slab formed by cooling in the first mold part 41 is thin, as described above. Crushing occurs at the adjuster sol mold entrance.

On the other hand, if the length of the first mold part 41 (fixed mold) is long, the deformation of the slab will progress considerably due to uneven cooling within the first mold part, and the uneven cooling due to the adjustable molding F will cause the slab to deform considerably. It is no longer possible to expect the Sung Dynasty to have any effect on suppressing the deformation of slabs by means of protection.

■ Also, the pressing force of the adjustable mold (tt)
Because ilN is not removed, the frictional force between the adjustable mold and the solidified layer on the surface of the molten metal constantly increases, crushing the cast H and causing the molten metal in the solidified slab to overflow.
The molten steel within the solidified slab may be pushed back by the static pressure, resulting in insufficient cooling.

2) Decrease in operational reliability due to the adoption of the bell crank mechanism■ This is a system in which the movement direction of the adjusting device 45 (hydraulic cylinder) is changed by the bell crank 46 to operate the wall portion 44 (cooling plate) of the adjustable mold. ,
Continuous casting equipment ζ under high temperature, high humidity and dusty environmental conditions
, reliable operation cannot be expected.

■ Since the wall portion 44 (cooling plate) is supported via a universal joint 49 (ball clasp) and the bell crank 46 is connected to the wall portion 44 (cooling plate) by a pin 51 having a play 50, 1 Unable to set accurate pressure amount.

The present invention has been made in view of the disadvantages of the conventional technology, and its purpose is to uniformly cool the slab and prevent deformation and cracking of the slab. The purpose of the present invention is to provide an adjustable mold that can be expected to operate accurately over and over again.

[Means to solve the problem]

In order to achieve the above object, the gist of the present invention is to provide continuous casting equipment in which a tundish and a cylindrical mold are hermetically connected. In the adjustable mold configured to be movable in the direction, the inner diameter of the mold is adjustable and fixed by a position adjustment device disposed at the entrance of the adjustable mold, and the outlet of the adjustable mold is disposed in the radial direction of the casting cross section. A first invention provides an adjustable mold that is movable in the direction by a fluid pressure cylinder, and in the first invention, the position adjustment device includes a fluid pressure cylinder, and the adjustable mold is moved by the fluid pressure cylinder. The second invention is an adjustable mold characterized in that the inner diameter of the mold can be expanded or contracted.

[Effect]

The inlet inner diameter of the adjustable mold that follows the cylindrical mold that is hermetically connected to the tundish is adjusted by a position adjustment device so that it matches the outlet inner diameter of the cylindrical mold, so that the slab can be drawn out smoothly. By moving the outlet of the adjustable mold in the radial direction of the casting section using a fluid pressure cylinder and bringing the elements into contact in accordance with the shape of the slab surface, the slab can be cooled uniformly.

In addition, the static pressure of the molten steel in the final stage of casting is low and the temperature of the molten steel is low, so the surface of the slab is often rough and the inner peripheral surface of the adjustable mold is easily damaged. By operating the fluid pressure cylinder of the position adjustment device installed at the entrance of the mold and the fluid pressure cylinder of the adjustable mold in the direction of mold diameter expansion, the inner peripheral surface of the adjustable mold will not be damaged by the rough surface of the slab. .

〔Example〕

Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a cross-sectional view of the main parts of horizontal continuous steel casting equipment. In FIG. 1, 1 is a tundish that stores molten steel M, and a cylindrical mold mold is used as a fixed mold for this tundish 1.

- The mold tube 2 is hermetically connected via a connecting refractory 3, and adjustable molds 4a and 4b used as movable molds are installed following the mold tube 2, and a drawing roll 5 is installed downstream of the mold tube 2. There is.

First, an overview of continuous casting using horizontal continuous casting equipment will be explained based on the above configuration.

The molten steel M is supplied to the tundish 1 and temporarily stored there, and then flows into the mold tube 2 via the connecting refractory 3. However, at the same time as it comes into contact with the inner peripheral wall of the mold tube 2, the contact surface, that is, the outer periphery of the molten steel Solidified layer S. However, since the thickness of the solidified layer Sc in the mold tube 2 is smaller than the diameter of the molten steel, the strength of the slab in this portion is not sufficient. As the slab S is cooled by the adjustable molds 4a and 4h, the thickness of the solidified layer Sc increases, and the thickness of the solidified layer Sc near the exit of the adjustable mold 4b has reached 10 to 50 mm.
It has sufficient strength. After this slab is pulled out by a drawing roll 5 located further downstream, it is cut into appropriate dimensions by a cutting device.

Examples of the present invention will be described in detail below.

Since the equipment shown in Fig. 1 is for obtaining slabs with a circular cross section, the mold tube 2 is an integral cylindrical piece made of prepared alloy, and the cross section of the hollow part is changed by cooling. It is formed into a cylindrical shape with a taper that is reduced in the casting direction in anticipation of shrinkage of the slab. A cooling water jacket 6 is installed outside the mold tube 2, and cooling water supplied from the cooling water jacket 6 flows along the outer peripheral wall of the mold tube 2.

Next, the adjustable mold 4a installed subsequent to this mold ``Chi 16-B 2'' will be explained.

For adjustable blades 4. -1 is the second 1(a)
A total of four elements 7 surrounding the circular hollow part as shown in
．． A cylindrical body is formed from 1.7b, 7c, and 7d. Each element 7a, 7b, 7C17d, respectively,
1-8 Graphite rhino on the inner surface of the cooling plate 9 made of prepared alloy
-10 is attached. A plurality of pipes 11 through which cooling water flows are arranged within the cooling plate 9. (In Figure 1, the cooling water is
(a and 4b, one end E of which flows in, and the other end E, which is discharged in a direction perpendicular to the plane of the paper)
In Figure (a), graphite Leiko-10 has heat resistance and self-lubricating properties, so that the slab can be pulled out smoothly. 5. On the bottom side of the plate 8 at approximately the middle position in the direction (casting direction) of the center staple mold 4a. Engagement member 126. The end of the rod 14 of the near air cylinder 13 is fixed, and the first end of the cylinder 13 is fixed to the fixed frame J, ], 5.

Then, as shown in Figure 1,
The position adjustment screw 1"L (the tip of the screw 1"L is screwed into the support plate 17 protruding from the output side plate I/-1, 16 is 1.The frame 16f'', H is locked while the frame is 1.16ta1
- It is fixed to one metal fitting that can slide in the radial direction of the casting cross section (in the direction of both arrows) along the - surface (adjustable mold 4d side). A connecting member 21 connects one piece of hardware to an engaging portion +A20 fixed to the receiving part 11 of the adjustable mold 4a.

Therefore, by adjusting the position adjustment screw 18, the hardware 19 slides along the frame 1 (i) in the radial direction (input direction) of the casting section, so that it becomes integral with the engaging member 20 via the connecting member 21. Move the inlet side of the adjustable mold t"4a in the casting I bend 1" radial direction, and adjust the adjustable mold 4 to the inner diameter dimension of the exit L1 of the mold tube 2.
The input ['' of the adjustable mold 4a can be fixed at a position where the input 1-1 inner diameter and 1' dimension of a are matched.

Further, when the casting direction ratio of the adjustable mold 4a is close to 1, the connecting member 23 is connected to the engaging member 22 fixed to the adjustable mold 4a, and the play 1-24 at the other end of the connecting member and the adjustable mold 4a are connected to each other.
A spring 25 is interposed between the poles 1 and 2.
It is tightened at 6.

The adjustable mold 41) is also
) 4 Similar to what was shown? , four elements 7a.

It is composed of air cylinders 7b, 7c, and 7d, and an air cylinder having the same structure as the air cylinder 13 is disposed at an approximately intermediate position in the longitudinal direction (casting direction). Also, on each of the inlet and outlet sides of the adjustable mold 4b in the casting direction, a retaining member 22, a connecting member 23, and a play 1-2 having the same configuration as above are provided.
4. A spring 25 and a bolt 26 are provided.

FIG. 2(b) shows the element 7a1 of the adjustable mold.
1.7b, 7c, and 7d have rectangular inner hollow portions, and in this case, the hollow cross sections of the moldings 1 and 2 are also rectangular.

FIG. 3 shows a case where the position adjustment device is equipped with a fluid pressure cylinder, and the frame 16 on the exit side of the molding I:
Casting cross section radially sliding along? ) A piston 29 is slidably fitted along a hollow cylindrical portion 28 of a connecting member 27 connected to a metal fitting 19 that can be connected to a piston rod 30.
The distal end thereof is connected to an engaging member 20 fixed to the entrance side of the adjustable mold 4a. The hollow cylindrical portion 28 is composed of an upper inner chamber 31 and a lower inner chamber 32, and the upper inner chamber 31 is configured to allow high pressure fluid to flow therein. That is, the hollow cylindrical portion 28 and the upper inner chamber 31
, lower inner chamber 32, piston 29 and piston front 3
0 constitutes a fluid pressure cylinder.

During continuous casting, while high-pressure fluid is supplied to the upper inner chamber 3H, the inner diameter of the mold tube 2 is adjusted to match the inner diameter of the adjustable mold 4a.
The inner diameter of the adjustable mold 4a is adjusted and fixed by the two-position adjustment screw 1ε (6°2), and at the end of casting, the screw 1-front 30 moves in the direction B every time the high-pressure fluid in the upper inner chamber 31 is removed. The structure is such that the inner diameter of the entrance of the adjustable mold 4a can be instantly expanded.

Continuous casting in the case of manufacturing a billet with a circular cross section using the adjustable mold of this embodiment configured as described above will be described below.

(Behavior of the slab inside the mold tube 2) As shown in FIG. 1, the molten steel M flowing into the mold tube 2 from the tundish 1 is cooled in contact with the inner peripheral wall of the mold tube 2, and a solidified layer S is formed on the outer periphery. will occur. Then, as the slab S is pulled out by the drawing roll 5, the thickness of the solidified layer Sc gradually increases; Due to this increase in the thickness of the slab, the cross-sectional dimension of the slab gradually decreases. The mold tube 2 is a fixed mold and does not follow changes in the shape of the slab, but its inner periphery changes from the upstream side to the downstream side, taking into account the decrease in the cross-sectional dimension of the slab. It is formed into a tapered shape so that its cross-sectional dimension decreases. However, as the shrinkage rate of the slab varies depending on many factors as mentioned above, it is impossible to maintain uniform contact between the inner peripheral wall of the mold tube 2 and the slab in all cases, as shown in Fig. 4. like,
The slab S is slightly deformed and a gap G is created in a part of the contact portion with the inner circumferential wall of the mold tube 2, resulting in a slightly uneven contact state, and partial cooling progresses to some extent. As a result, the shape of the slab on the outlet side of the mold tube 2 is slightly deformed. Therefore, mold tube 2 as a fixed mold
The shorter the length, the better, but on the other hand, if it is too short, the thickness of the solidified layer will be too thin and the strength of the slab will be too low, making the slab easy to break and the hot molten steel inside to blow out. Therefore, the length of the mold tube 2 cannot be shortened below a certain value.

(Behavior of slab in adjustable mold 4a) This will be explained based on FIG. 1 and FIG. 211ffl(a).

A position adjustment screw 1 is installed on the entry side of the adjustable mold 4a.
8 is provided, the positions of the four elements 7a, 7b, 7c, and 7d are adjusted using the position adjustment screw 18 to match the inlet inner diameter of the adjustable mold 4a with the outlet inner diameter of the mold tube 2. By this,
The slab S can be pulled out smoothly. Then, as the slab S is pulled out by the drawing roll 5 on the downstream side, the thickness of the solidified layer SC of the slab S gradually increases toward the downstream side while being indirectly cooled by the cooling plate 9. The cross-sectional dimension of the slab S gradually decreases. However, since the thickness of the solidified layer Sc of the inlet slab S is considerably thinner than that on the outlet side, the strength of the inlet slab is low. Therefore, if the amount of movement of each element of the adjustable mold 4a in the radial direction of the casting cross section is not controlled in the longitudinal direction of the slab, all moving elements are likely to hit unevenly against the slab on the entry side, which has low strength.
As a result, the entrance slab may crack.

However, an air cylinder 13 is disposed approximately in the middle in the longitudinal direction of the adjustable mold 4a, and this air cylinder 13 resists the spring force of the spring 25 to move the elements 7a, 7b, and 7C17d around the inlet E as a fulcrum. Since it is biased in the direction of diameter reduction, the element 7 is
a, 7b, and 7C17d follow, making it possible to ensure contact between the adjustable mold 4a and the slab S over a wide range of the slab S. As a result, the slab S is cooled uniformly within the adjustable mold 4a, and deformation and uneven cooling hardly progress. Furthermore, elements 7a, 7b, 7c, 7
Since the graphite liner 10 is attached to the inner surface of d,
Friction with the slab S is reduced, and cracking of the slab can be more reliably prevented.

(Behavior of the slab in the adjustable mold 4b) As shown in Fig. 1, the thickness of the solidified layer Sc of the slab S cooled in the adjustable mold 4a is the It is approximately half the thickness and has sufficient strength. Therefore, when each element of the adjustable mold 4b is biased in the diametrical direction by the air cylinder 13 against the spring force of the spring 25, each element 7a, 7b, 7C27d is almost completely removed from the slab S. There is no uneven contact between the slab S and the adjustable mold '4h.

Zunawa ξ), the slab S is uniformly cooled in the longitudinal direction G as it is drawn by the drawing r-1-ru 5 on the downstream side, and its cross-sectional dimension shrinks at a constant rate 71. No deformation or cracking will occur.

In this way, the supplied molten button, ]M, is continuously pulled up and down by the drawing roll 5L (thus, it is continuously pulled up and down as a fixed mold.
2 and adjustable mold 4 as a movable mold
Through steps a and 4b, solidification progresses sequentially from the surface layer while being uniformly cooled, and the cross-sectional shape of the entrance side of the mold tip and the mold tip 2 shrinks in a similar manner to form a herend with a cross section close to a perfect circle. You can get 2-.

However, slabs in the final stage of casting tend to solidify unstable and often have rough surfaces, and if these rough areas pass through the mold as they are, the inside of the adjustable molds 4a and 4+ The graphite liner 10 attached to the circumference is 1. HI may cause injury. However, the third
762, when the position adjustment device disposed at the entrance of the adjustable drying rail F'4a is equipped with a fluid pressure cylinder, the cylindrical portion 28 constituting the fluid pressure cylinder is
By removing the high-pressure fluid from +B1 to the inner chamber 31, the screw rod 30 is moved in the direction of the arrow 13 to enlarge the inner diameter of the adjustable mold 4a, and at the same time, the air cylinder of the adjustable mold 4a and 41 is expanded. - There is no possibility that the graphite liner 10 will be damaged by moving the liner 13 in the direction of the diameter expansion force.

[Effects of the Invention] Since the present invention is configured as described above, the following effects are achieved.

■Each element of the adjustable mold is a fixed piece.
It moves in the radial direction (diameter reduction direction) by an amount corresponding to the solidification shrinkage of the slab, centering on one part, and uniformly cooling each element and the surface of the slab. Because of this, the low strength cast slab with a thin solidified layer is not crushed at the high temperature of mold tube exit 1, and there is no deformation or cracking of the cast slab, or bulging (bulging due to internal pressure), and the rust-hardened silk weave is prevented. It is possible to obtain high-quality slabs that are axially symmetrical.

■Adjustable Mold - Each time the position adjustment device installed on Person I-1 is adjusted, 1. Adjustable mall 1゛ entrance 4 yen dimension
] By matching the inner diameter dimension G, the slab can be drawn smoothly.

■By moving the inlet 1 and outlet 1'iT of the adjustable mold in the diametrical direction by a fluid pressure cylinder according to the surface condition of the slab passing through, the inner circumferential surface of the adjustable mold 1 is There will be no damage.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the main part of horizontal continuous casting equipment using an adjustable mold according to the present invention (1t'; l), and Figure 2 (a) is a cross-sectional view taken along the line CC in Figure 1. (b) i;
Fig. 2(a) is a diagram showing the case where the hollow part of the adjustable mold is rectangular, and Fig. 3 is an enlarged sectional view of a position adjustment device equipped with a fluid pressure cylinder disposed in the inlet L of the adjustable mold. , Figure 4 shows molded chino, -bu(
Figure 5 explaining the cross-sectional shape of the slab in the cylindrical mold)
1 is a side cross-sectional view of a horizontal continuous casting equipment according to the prior art, and FIG. 6 is an enlarged view of the second mold part (movable mold) of the prior art, partially shown in cross section. ■...Tandishico 2.2...Mold Chico, -bu,
4a, 4b... Adjustable molding F, Maa. 7b, 7c, 7d, 7a+, 7b+, 7c+, 7d+
``Element, 9...Cooling plate, 10...Graphite liner, 13...
・Air cylinder, ■Position adjustment screw, 28..Hollow cylindrical part, 29..Piston 1.30..Piston rod, 31..Upper inner chamber, 32..Lower inner chamber CO-O dimensions LnLr) Sounds

Claims (1)

[Scope of Claims] 1) A continuous casting equipment in which a tundish and a cylindrical mold are hermetically connected, and subsequent to the cylindrical mold, the casting cross section is divided into a plurality of elements in the circumferential direction and is movable in the radial direction of the casting cross section. In the adjustable mold configured as shown in FIG. 2) The adjustable mold is movable in the above direction. 2) The position adjustment device includes a fluid pressure cylinder, and the inner diameter of the adjustable mold can be expanded or contracted by the fluid pressure cylinder. adjustable mold