JP2892109B2 - Continuous forging device for continuous cast strand - Google Patents

Description

[Detailed Description of the Invention] (Industrial application field) Center segregation occurring in a forged piece obtained by continuous forging is caused by solidification shrinkage at a solidification tip portion of a continuous cast strand drawn from a mold, bulging of a solidified shell, and the like. The pores serve as a suction force, and the concentrated molten steel at the tip of the solidification is sucked into the solid-liquid coexistence region, and C, S, P
Etc. appear as enrichment and positive segregation, and cause deterioration of mechanical properties and lamination etc.,
It was one of the inevitable quality defects in continuous casting. In order to reduce or avoid such center segregation, the unsolidified molten steel ( It is effective to apply a reduction in the thickness direction in the vicinity of the final solidification zone of the concentrated molten steel).

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forging device suitable for applying an effective reduction in a final solidification region of unsolidified molten steel of a continuous cast strand during a drawing movement of the continuous cast strand, and particularly relates to a forging device for mutually approaching and separating anvils. An object of the present invention is to prevent deformation of a continuous casting strand on the exit side of an anvil, which is inevitable when performing forging with reciprocating motion.

(Prior art) Japanese Patent Application Laid-Open No. 62-12 / 1987 discloses a forging device for continuous cast strands.
7148, JP-A-63-49353 or JP-A-1
A number of proposals have already been made, such as in -273657.

Here, all of the devices disclosed in the above-mentioned documents perform forging on a continuously cast strand drawn from a continuous casting mold by reciprocating drive in which an anvil sandwiching the strand in the thickness direction repeatedly approaches and separates each other. Thus, according to such an apparatus, the internal quality of the continuous cast slab could be remarkably improved. By the way, in an apparatus having such a type, when a continuously cast strand drawn from a continuous casting mold is subjected to uneven cooling or inappropriate cooling in a secondary cooling zone or the like, when forging processing is performed. Since the amount of reduction differs depending on the reduction area, there was a concern that the strand would be significantly deformed vertically or horizontally on the exit side of the forging device, causing trouble in operation. This tendency is particularly remarkable when the working amount is increased in accordance with the thickness of the unsolidified molten steel of the continuous cast strand. Also,
In such an apparatus, a pinch roll for drawing the continuous cast strand at a constant speed is installed on the outlet side. However, since the strand is extended (especially in the longitudinal direction) during forging, the rotation of the pinch roll and the strand Intermittent deviation from the moving speed of the pinch roll, which could cause breakage of the pinch roll. In this regard, attempts have been made to appropriately change the number of rotations of the pinch rolls. However, fluctuations in the number of rotations have been slowed down due to fluctuations in the molten steel level in the continuous casting mold (stable at about ± 2 mm). It is not an effective means to promote defects such as bites and surface cracks.

(Problems to be Solved by the Invention) It is an object of the present invention to propose a new apparatus capable of solving the above-mentioned problems which have been conventionally concerned in the forging of a continuous cast strand.

(Means for Solving the Problems) The present invention relates to a continuous casting strand that is being drawn out from a continuous casting mold by a reciprocating drive that repeatedly sandwiches the continuous casting strand drawn out from a continuous casting mold in a thickness direction. In an apparatus provided with a pair of anvils for forging, a group of pinch rolls for pulling out and moving a continuous cast strand is installed on the entry side of the anvil, and a change in the moving speed of the strand due to forging is provided on the exit side. A continuous forging device for continuous cast strands, wherein at least one set of roll pairs capable of changing the rotational drive speed in accordance therewith is provided.

FIGS. 1 (a) and 1 (b) show the structure of a forging device according to the present invention. In the drawing, reference numeral 1 denotes a continuous casting strand, and reference numerals 2a and 2b denote anvils sandwiching the continuous casting strand in the thickness direction. anvil, for example, the anvil 2a is fixedly held to a frame 3 which is swingably connected to the crankshaft C via a level adjusting hydraulic cylinder s _1, anvil 2b
Is pivotally connected at one end to a crankshaft C via a _second hydraulic cylinder s2 for level adjustment.
Is fixedly held on a slide block B slidable along the rod 3a, and the anvils 2a and 2b repeat reciprocating movements of approaching and separating from each other by rotation of a crankshaft C connected to a driving source, thereby forming the continuous casting strand 1. Perform forging. Here, in the above configuration, when the anvils 2a and 2b approach each other, the frame 3 moves with the pulling movement of the continuous casting strand. Therefore anvil 2a, 2b is assumed to provide a hydraulic cylinder s ₃ to righting the frame 3 to the initial state in the process of separating each other.

Reference numeral 4 denotes a group of pinch rolls, which are arranged on the entry sides of the anvils 2a and 2b and control the pulling movement of the continuous cast strand 1;
b is a pair of rolls arranged on the exit side of the anvils 2a and 2b and at least one of the upper and lower sides is connected to a drive source (not shown). The pair of rolls 5a and 5b The rotational drive speed can be changed by, for example, current control according to the intermittent change in the moving speed (elongation by forging). The pair of rolls 5a and 5b can be continuously subjected to the pull-out movement of the continuous cast strand 1 when the top portion (the head after the completion of casting) of the continuous cast strand 1 has passed through the pinch roll group 4 as well as forging. It has the role of avoiding the deformation of the continuous cast strand caused by the above. 6
Is a housing for accommodating the roll pair 5a, 5b, and 7 is a roll 5a
Of the continuous casting strand 1 between the roll pair 5a, 5b
And a hydraulic cylinder which generates a drawing torque of the continuous cast strand 1 and widens the interval between the roll pairs when passing through a dummy bar or the like, and 8 has one end to the housing 6 and the other end to the roll pair 5a. Roll chock 5c
This is a sensor for detecting the amount of elevation of the roll 5a connected to the roller 5a.

(Operation) When the interval between the rolls of the pinch rolls 4 is set so as to obtain a predetermined drawing torque, and the forging pressure of the continuous casting strand 1 is performed while driving at a constant rotation speed, the anvil is formed.
On the outlet side of 2a, 2b, the moving speed due to the extension of the continuous casting strand 1 fluctuates intermittently with the forging process. In the apparatus according to the present invention, the rotation speed of the roll pair 5a, 5b is shown in FIG. As shown in the drawing, the roll is changed in accordance with the timing of the rolling, so that the roll is not damaged due to the difference in the number of rotations, and the deformation of the continuous cast strand 1 is also caused by this roll pair.
It is suppressed by the holding force of 5a, 5b. Further, since the continuous casting strand 1 is pulled out by the anvils 2a and 2b with a predetermined pinching force, the fluctuation due to the extension of the continuous casting strand during forging is absorbed here, and the molten steel level in the continuous casting mold is reduced. It is kept almost constant.

In this example, the roll pair 5a, 5b
Although the case where one set is provided is shown, the number of the set can be increased as necessary.

In the case where the above-mentioned roll pair 5a, 5b cannot be arranged on the exit side of the anvil due to equipment limitations, first, a non-driving type roll capable of pressing the continuous cast strand after forging into the position with a predetermined clamping force. May be provided in advance and installed downstream thereof.

Applying a continuous casting machine with a continuous casting mold with a mold width of 560 mm and a thickness of 400 mm, rolling reduction 200 mm while continuously casting steel types such as low carbon aluminum killed steel, bearing steel, high tensile steel, alloy steel, Forging was performed with a slab surface temperature difference of 150 ° C. and a rolling force of 60 tons on the roll pair on the exit side of the anvil. However, good forging was performed without warping of the slab strand.

(Effects of the Invention) Thus, according to the present invention, deformation of the continuous casting strand on the exit side of the anvil and fluctuation of the molten metal level in the continuous casting mold, which have been problems when forging the continuous casting strand, can be advantageously avoided.

[Brief description of the drawings]

1 (a) and 1 (b) are explanatory diagrams of the configuration of the device according to the present invention. FIG. 2 is an explanatory diagram of the driving situation of a pair of rolls arranged on the exit side of the anvil. DESCRIPTION OF SYMBOLS 1 ... Continuous cast strand, 2a, 2b ... Anvil 3 ... Frame, 4 ... Pinch roll group 5a, 5b ... Roll pair, 5c ... Chock 6 ... Housing, 7 ... Hydraulic cylinder 8 ... Sensor s ₁ , s ₂ , s ₃ …… Hydraulic cylinder C …… Crankshaft

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B22D 11/28

Claims (1)

(57) [Claims] 1. A pair of anvils for holding a continuous casting strand drawn from a continuous casting mold in the thickness direction and forging the continuous casting strand during the drawing movement by reciprocating drive which repeats mutual approach and separation. In the apparatus provided, a group of pinch rolls for taking out and moving the continuous cast strand is installed on the entrance side of the anvil, and the rotation drive speed can be changed on the exit side according to the change in the traveling speed of the strand accompanying forging processing. A continuous forging device for a continuous cast strand, comprising at least one set of roll pairs.