JPH0214139B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The technical content described in this specification relates to the reduction of center segregation that occurs at the center of the thickness of forged sheets obtained by continuous casting. The object of the present invention is to propose a forging device that advantageously reduces center segregation that occurs at the center of the plate thickness as much as possible and is convenient for processing into sound slabs.

The center segregation that occurs in slabs obtained by continuous casting is
At the center of thickness near the final solidification point of the slab, C.
Molten steel components such as SP become concentrated and appear as positive segregation.

This center segregation causes deterioration of mechanical properties and the occurrence of lamination, and is one of the quality defects that cannot be avoided using conventional forging methods.

The above-mentioned center segregation generation mechanism is that pores generated by solidification shrinkage at the solidified tip of the slab and bulging of the solidified shell act as absorbing force, sucking the concentrated molten steel at the solidified tip and moving it straight to the center. This is due to the fact that it remains as segregation.

(Prior art) In order to prevent such center deflection of slabs,
For example, attempts have been made to use electromagnetic stirring in the secondary cooling zone, but this has not been able to reduce semi-macro segregation, and the effect cannot be said to be sufficient.

On the other hand, Japanese Patent Publication No. 59-16862 discloses a method in which the vicinity of the solidified tip of the slab is lightly rolled down using rolls, and JP-A-53-40633 discloses a method in which the vicinity of the solidification completion point of the slab is rolled down into a planar shape. It is disclosed that the forging process is performed using a forging die.

(Problems to be Solved by the Invention) The method of compensating for the amount of solidification shrinkage at the solidification tip under light pressure by the rolls described above can only reduce the amount of solidification shrinkage at the tip in the casting direction, so the solidification shrinkage occurring between the rolls is Unable to sufficiently prevent bulging,
Further, since this reduction acts as a linear concentrated load in the width direction of the slab, internal cracks are likely to occur at the solidification interface, and there is a drawback that a large reduction cannot be achieved.

In addition, in the case of light reduction using the rolls mentioned above, if the amount of reduction is small, most of the deformation will occur near the surface of the slab, and it is also difficult to effectively reduce the solidification interface required to prevent center deflection. It will be done.

On the other hand, in the method of forging with a forging die, (1) Since it is a surface reduction, it is possible to effectively reduce the slab to the solidification interface compared to roll reduction.

(2) The machined surface of the forging die can be set so that the strain at the solidification interface of the slab is small, and the frictional force between the forging die surface and the slab during rolling can also be set to reduce compressive strain at the solidification interface. Since it acts in the direction of generation, the amount of reduction can be larger compared to the reduction with rolls.

(3) Because of the surface support, center segregation due to bulging can be prevented, and an improvement in center segregation can be expected compared to roll rolling.

It is more effective in these respects.

However, when forging with the above-mentioned forging die, a large forging force is required (for example, about 3000 to 5000 tons for slabs) compared to roll reduction.
It is difficult to compactly fit such a forging device into a continuous casting facility, and it also prevents the slab from moving smoothly during the rolling process using the forging device, making it difficult to put it into practical use. The reality is that this has not been done.

The present invention aims to avoid the center segregation of slabs obtained by continuous casting without impairing the advantages of the above-mentioned forging process, and to easily obtain a healthy cast edge by drawing slabs using a compact mechanism. The purpose is to propose a forging device that can perform reliable forging processing without hindering movement.

(Means for Solving the Problems) The present invention includes a pair of forging dies that vertically sandwich a slab obtained by continuous casting in the vicinity of the solidification completion point, and the casting die by this forging die. During the step of rolling down the slab in the thickness direction, it moves and follows the drawing movement of the slab,
In a continuous forging machine, in which the forging die is movable up and down in the bogie frame body, which is restored and moved during the rolling release process, a pair of upper die support metal fittings that hold the upper forging die are sandwiched on the left and right sides. The lowering lever and a pair of lowering levers that sandwich the lower mold support metal fittings holding the lower forging mold on the left and right sides are pivotally connected to the truck frame at one end thereof, and the other end of the upper lowering lever is connected. They are connected together by a beam, and the other end of the lower lever is connected together by a joint, and a portal frame is pivotally connected to this joint by a support pin that passes through it laterally. This is a continuous forging device for continuous casting, characterized in that a hydraulic device is installed between the connecting beam and the connecting beam.

(Function) The bogie frame body of the forging device moves and follows the drawing movement of the slab during the rolling process of the slab by the pair of upper and lower forging dies provided therein, and the forging die opening process is performed by following the drawing movement of the slab. Some of them have a structure that allows them to be moved back to their original positions, so that the work can be done smoothly without interfering with the movement of the slab during the rolling process.

In addition, a pair of upper and lower forging molds provided on the bogie frame body are respectively attached to the upper and lower pressure levers via mold support metal fittings, and are assembled to move up and down reciprocally with the slab sandwiched between the upper and lower sides. ing. When the slab is rolled down by the operation of the hydraulic device, a forging reduction force is applied to the forging die by the lever principle.

In other words, this forging reduction force is as follows: P is the forging reduction force, F is the thrust by the hydraulic device, and b is the length from the pivot connected to the bogie frame to the forging die.
If the length from the above-mentioned axis to the hydraulic device is a, then P=(a/b)F, and the forging reduction force P
The relationship between this and the thrust force F generated by the hydraulic device is determined by the lever ratio (a/b). Therefore, if the lever ratio is set high, even a hydraulic device with a small thrust can easily press down the slab.

Therefore, the above-mentioned forging device has a compact mechanism that makes it easy to forge slabs, and also allows for easy rolling →
Since the slab is rolled down in a follow-up → release → return cycle, reliable forging can be performed without interfering with the drawing movement of the slab.

(Example) Examples will be described below.

In Fig. 1, 1 is a slab, 2 is a support roll, 3 is an upper forging die, 3' is a lower forging die, 4 is an upper die support metal fitting that holds the upper forging die, and 4' is a lower forging die. Lower mold support hardware that holds the mold, 5 is an upper pressure lower lever, 5'
is the lower lever.

Further, 6 is a truck frame, 7 is a wheel bearing hardware fixed to the truck frame, 8 is a wheel, 9 is a rail, 10 is a restoring device, 11 is a fixing hardware that fixes the restoring device 10 to the foundation, and 12 is a restoring device. It is a metal holder that connects devices.

Reference numeral 13 denotes a pivot shaft that pivotally connects one end of each of the upper pressure-down lever 5 and the lower pressure-down lever 5' to the truck frame 6; 14 a joint beam that integrally connects the other end of the upper pressure-down lever 5; Reference numeral 15 designates a fitting that connects the other end of the lower pressure lever together, 16 a support pin that passes through the fitting 15 laterally, 17 a portal frame, 18 a hydraulic device, and 19 a hydraulic device. device 18
The metal fitting 20 attached to the metal fitting 20 is a receiving metal fitting for receiving the metal fitting 19.

First, the main body of the bogie frame of this forging device is held by a pair of rails 9 via wheels 8 provided at the lower part of the bogie frame 6. The restoring device 10 fixed to the foundation directly below this is integrally connected to the restoring device 10 by a metal holder 12 fixed to the lower surface of the truck frame 6.

The upper forging die 3 and the lower forging die 3' are each provided in the above-mentioned truck frame 6, and the upper forging die 3 is held by the upper die support metal fitting 4, and the lower forging die 3' is held by the lower forging die 3'. It is held by a mold support metal fitting 4'. Furthermore, the mold supporting hardware 4, 4' is connected to a pair of lowering levers 5, which sandwich it on the left and right sides, respectively.
5' (Fig. 1 C-C
cross section).

The lowering levers 5 and 5' are arranged opposite to each other to sandwich the cast strip above and below, and are connected at one end to the truck frame 6 via a pivot shaft 13 (cross section taken along line A-A in FIG. 1). .

On the other hand, the other end of the upper lowering lever 5 is integrally connected to the left and right lowering levers by a connecting beam 14, and the other end of the lower lowering lever 5' is integrally connected to the left and right lowering levers by a joint 15. . The other end of the lower lever 5' is further pivotally connected to the portal frame by a support pin 16 passing through the joint 15 laterally (see section DD in FIG. 1).

At the top of this gate-shaped frame 17, a hydraulic device 1 is provided.
8, as shown in the cross section D-D in Figure 1,
By means of the metal fitting 19 attached to this hydraulic device 18 and the receiving metal fitting 20 attached to the joint beam 14,
The upper part of the portal frame 17 and the other end of the upper and lower levers 5 are connected.

Therefore, when the metal fitting 19 at the tip of the rod presses against the joint beam 14 due to the operation of the hydraulic device 18 installed between the portal frame 17 and the other end of the upper and lower levers 5, the pivot shaft 13 is used as a fulcrum. Based on the lever principle, a forging reduction force is applied to the upper forging die 3 and the lower forging die 3'.

Here, the shape of the metal fitting 19 of the hydraulic device 18 is made into a spherical shape, and the joint beam that receives it is made into a spherical seat. As a result, the relative angle between the upper pressure lowering lever 5 and the portal frame 17 can be changed smoothly.

Note that when opening the upper forging die 3 and the lower forging die 3', the rear end of the stopper fitting 9 is received by the receiving fitting 20 attached to the connecting beam 14, so that the upper forging die 3 and the lower forging die 3' can be easily opened. At this time, the stopper 21 is positioned so that the upper surface of the lower forging die 3' is slightly below the pass line of the slab 1, and if the stopper 21 receives the lower end of the portal frame 17, the liquid will flow. This is advantageous in minimizing the operating stroke of the pressure device 18.

Here, the shape of the forging die used in this forging press will be explained.

FIG. 2 shows the cross-sectional shapes of the upper forging die 3 and the lower forging die 3'. The rolled surface of this forging die had a shape consisting of a tapered part and a flat part. The required reduction amount δ (on one side) of the slab 1 is determined by the slope of the tapered part, and the reduction is completed when the required reduction amount δ is reached. This is advantageous from the viewpoint of preventing cracking.

In order to flatten the surface of the slab after rolling is completed, the length of the flat part l ₂ is the feed amount f per one rolling cycle (where rolling pitch time t and forging speed v _c are given, then f = v _ct ) should be larger.

Further, the thickness _h2 of the slab 1 at the point of completion of rolling can be easily adjusted by attaching a pair of stoppers 22 to the lower part of the joint beam 14 or the upper end of the joint fitting 15, for example, as shown in the cross section DD in FIG. can be adjusted to

Incidentally, as for the shapes of the upper forging die 3 and the lower forging die 3', in addition to those described above, a planar die may be used depending on the case.

(Effects of the Invention) Since the forging press device according to the present invention is a rolling down mechanism that utilizes the lever principle, it is possible to obtain a large forging force even if the hydraulic device 10 is miniaturized, and the entire device is simple and compact. Because of this configuration, it can be incorporated into existing continuous casting equipment where space is limited, and equipment costs can be reduced. In addition, it is possible to perform smooth and reliable forging work on the slab being poured without interfering with the movement of the slab, and the structure allows it to follow the lifting of the slab, resulting in highly reliable forging work. can be done.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of a forging press according to the present invention (a plan view, an A-A sectional view, a C-C sectional view, a D-D
2 is a diagram showing the cross-sectional shapes of the upper forging die 3 and the lower forging die 3'. 1... Slab, 2... Support roll, 3... Upper forging die, 3'... Lower forging die, 4, 4'... Mold support hardware, 5... Upper pressure-down lever 5'... Lower lever,
6... Bogie frame body, 7... Wheel bearing hardware, 8...
Wheel, 9...Rail, 10...Restoration device, 11...
... Fixed hardware, 12... Receptacle, 13... Pivoting axis,
14... Joint beam, 15... Fitting, 16... Support pin, 17... Portal frame, 18... Hydraulic device, 19... Fitting, 20... Receptacle, 21
...Stopper, 22...Stopper that limits the thickness of the slab.

Claims (1)

[Scope of Claims] 1. A pair of forging dies that sandwich the slab above and below near the solidification completion point of the slab obtained by continuous casting, and during the process of reducing the slab in the thickness direction using the forging dies. In a continuous forging device in which the forging die is movable up and down in a bogie frame body that follows the drawing movement of the slab and moves back to its original position during the rolling release process, an upper forging die is provided. A pair of lowering levers that sandwich the upper mold support hardware holding the lower forging mold on the left and right, and a pair of lowering levers that sandwich the lower mold support hardware holding the lower forging mold left and right, are connected to the trolley at one end of each of them. It is pivotally connected to the frame, and the other end of the upper pressure-down lever is integrally connected with a joint beam, and the other end of the lower pressure-down lever is integrally connected with a joint, and is connected to a support pin that passes through this joint laterally. A continuous forging device for continuous casting, characterized in that a gate-shaped frame is pivotally connected to the gate-shaped frame, and a hydraulic device is installed between the gate-shaped frame and the joint beam.