JPH04274854A - Continuous forging pressure method for cast strand in continuous casting - Google Patents

Abstract

PURPOSE:To prolong a service life and to realize a stable operation by avoiding the abnormal sound and the vibration of a device which are difficult to avoid in the case of performing forging pressure working to on a cast strand, in the drawing process of the cast strand concerned in a continuous casting. CONSTITUTION:Plural sets of anvils 1a, 1b for forming one set by a pair for holding an ingot strand S drawn by a continuous casting mold therebetween by both sides are prepared, and when continuous forging pressure working is performed at the solidification completion area of the cast strand S for passing through between the anvils by the reciprocating operation of the respective mutual approach and separation of each anvil by driving to rotate a single crank shaft 5 connected to a driving source M through a speed reducer G, the forging pressure working by one set of anvils is finished and the anvils are separated mutually, and also, in a stage in which negative torque is generated, forging pressure working by other anvils is started.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is applicable to cast slab strands obtained by continuous casting (materials for high-grade wire rods with problems such as center segregation and roughness, materials for high-Cr seamless materials, materials for high-grade thick plate materials). The aim is to reduce the noise and vibration of the forging equipment that is unavoidable when applying forging during the drawing process to improve the quality of the forging (e.g.), thereby extending the lifespan and stable operation of the forging equipment.

0002

[Prior Art] A forging device equipped with an anvil that pinches a slab strand drawn from a continuous casting mold in the thickness direction and repeatedly approaches and separates the slab strand from each other to apply a forging process to the area near the solidification completion point of the slab strand. For example, a structure disclosed in Japanese Unexamined Patent Publication No. 2-70363 is known. Such equipment is usually equipped with a hydraulic cylinder to prevent overload during forging and to adjust the mutual spacing between anvils. In cases where the difference between the pressure in the cylinder and the pressure in the cylinder during forging is as much as 200 kg/cm2, the compression of the hydraulic fluid reduces the pressure by approximately 1%.
Due to a slight change in volume, even when the anvils move from being closest to each other to being separated from each other, a reduction force remains due to the compression of the hydraulic fluid, which creates a negative torque on the crankshaft. In connected reducers, etc., the tooth surfaces of the gears collide with each other due to the gap caused by backlash, which has the disadvantage of generating abnormal noise (impact noise) and vibration, which can have a significant negative impact on the lifespan and stable operation of the equipment. was there.

0003

[Problem to be solved by the invention] To prevent fluctuations in the load direction caused by the amount of compression of the working fluid in a forging machine that has a structure in which hydraulic cylinders are arranged, and to provide stability for a long period of time without abnormal noise or vibration. It is an object of the present invention to propose a new method that can perform a forging operation with a high degree of precision.

0004

[Means for Solving the Problems] The present invention provides a plurality of pairs of anvils that sandwich a slab strand pulled out from a continuous casting mold on both sides, and connects the cast slab strand drawn from a continuous casting mold to a drive source via a speed reducer. When a single connected crankshaft is driven to rotate and each anvil moves toward and away from each other in a reciprocating manner, continuous forging is performed on the slab strands passing between them, and the forging with a set of anvils is completed. This is a continuous forging method for a slab toss land, which is characterized by starting the forging process using another anvil at the stage when a negative load torque is generated.In this invention, the load torque of the crankshaft is as follows. It is best to set the value to a value that satisfies the following conditions. Tmin /TR ≧-0.5 Tmin: Minimum value of load torque TR: Rated torque of reducer Tmin /TR ≧-0.5 Tmin: Minimum value of load torque TR: Rated torque of reducer

FIG. 1 shows the configuration of a four-strand processing apparatus suitable for carrying out the present invention, and the case where forging processing is performed using this apparatus will be described below. In FIG. 1, numbers 1a and 1b are arranged to sandwich the slab strand S and are anvils that control the forging process of the strand S, 2 is a main frame, and 3 is movable along a guide portion 2a of the main frame 2. 4a and 4b are hydraulic cylinders that fix and hold the anvils 1a and 1b to the main frame 2 and subframe 3, respectively, and position them; 5 has one end attached to the reducer G;
This crankshaft 5 is connected to the main frame 2 and the subframe 3 via links l1 and l2, and its rotation causes the anvils 1a and 1b to are brought close to and separated from each other along with each frame, and a continuous forging process is applied to the final solidification region of the slab strand S. Also,
6 is a balance cylinder that prevents the rod of the hydraulic cylinder 4b from moving downward due to its own weight, and 7 is a displacement meter that measures the amount of displacement of the rod of the hydraulic cylinder 4b. Figure 2 shows a side view of the device having the above configuration, and 8 in the figure is a return cylinder for returning the main frame 2 and subframe 3, which have moved around the crankshaft 5 during rolling down, to their initial state. be.

[0006]

[Operation] Immediately after the completion of rolling during continuous forging and the state of separation from each other is shown in Figures 3 and 4, especially for the anvil 1a. Anvil 1a,
1b Even if the state in which the cylinders 1b are closest to each other (completion of pressure reduction) and the state in which they are separated from each other (opening of the anvil), the hydraulic cylinder 4
Since a reduction force remains due to the compression of the hydraulic fluid in a and 4b, this creates a negative torque on the crankshaft 5, and the connected reduction gear G, etc., inevitably produces abnormal noise and vibration due to backlash. It was. In the figure, P1 is the oil pressure on the head side of the hydraulic cylinder when the load on the anvil is zero (the oil pressure before pressure reduction at the supply pressure). P2 is the oil pressure when the anvil load is positive. P3 is the oil pressure when the anvil opens and the load becomes zero. T' is the load torque of the crankshaft in the state of P1. P' is the load axial force of the crank rod in the state of P1. a is the height of the oil sealed on the head side of the hydraulic cylinder in states P1 and P3. Δa is the amount of oil compression in the P2 state of the same sealed oil. FIG. 5 shows this relationship between the rotation angle of the crankshaft and the load torque. The torque due to the compressibility of the hydraulic fluid (oil) varies depending on the amount of change in the oil chamber of the hydraulic cylinder before and after compression, the length of the crank arm, etc., but the load torque is greater than a certain percentage of the rated torque of the reducer. This will cause wear and damage to the tooth surfaces of the reducer, and simply following this forging method will not allow smooth operation, and the life of the equipment will be extremely short.

In this invention, a plurality of sets of anvils are connected to a single crankshaft 5, and when a negative torque is generated after forging by one set of anvils, rolling by the next set of anvils is started. Since the anvil is driven at different timings to eliminate the negative torque caused by the reduction in the previous stage, abnormal noises and vibrations due to backlash caused by the reduction gear etc. can be advantageously avoided.

FIG. 6 shows how the rotation angle of the crankshaft 5 changes when a single slab strand is subjected to forging. In this case, the start of reduction is −α
°, and from this point on the anvil comes into contact with the slab strand. At a rotation angle of 90°, the anvils come closest to each other and the reduction ends, but due to the compressibility of the hydraulic oil and the elongation of the frame, the reduction force is maintained until the angle β, and during this period, the compressibility of the hydraulic oil causes a negative Torque is generated. In this invention, the reduction by another anvil is started in the range of angle β, which is the region where negative torque is generated, to offset the negative torque. Figure 7 shows this relationship for the forging process between two strands in a 4-strand forging process, and in this case, the reduction cycle is set so that the reduction of the strand in B starts when the process of the strand in A ends. do. In addition, the above figure 6
, the hydraulic cylinder 4a is omitted in FIG. Figure 8
1 shows a load torque curve of a crankshaft when four slab strands are subjected to forging according to the present invention. As shown in the figure, the end of rolling and the start of rolling during forging of the anvil are overlapped, and the total load torque on the crankshaft is set to positive or negative torque within a range that does not affect the strength or life of the reducer. By suppressing this, it is possible to prevent abnormal noise and vibration of the device due to load fluctuations. In addition, if it is not possible to reduce the negative torque to a range that does not adversely affect the equipment or operation due to various constraints such as operating conditions, the impact coefficient when the tooth surfaces collide due to backlash in the gears should be set to 2, and the load The load torque may be set as shown in the following equation, with the minimum torque of Tmin being Tmin and the rated torque of the reducer being TR. Tmin/TR ≧-0.5

[0009]

[Example] While continuously casting various slab strands of low carbon steel to high carbon steel having a width of 340 mm, a thickness of 270 mm, and a C content in the range of 0.05 to 1.2%, the above figure was cast. 1
A device configured as shown in (rolling force P: Max 60
0t, oil pressure p: 50-300 Kg/cm2, hydraulic oil: fatty acid ester, β: 5.3 × 10-5, crankshaft eccentricity r: 30mm, reducer rated torque T
Forging was performed under the conditions shown in Table 1 with R: 8 t-m and number of strands: 4), and a comparative investigation was conducted on the occurrence of noise and vibration in the device and the life of the gear in the reducer. The results are shown in Table 2.

0010

[Table 1]

[0011]

[Table 2]

[0012] As is clear from Table 2, by applying the forging process according to the present invention, the abnormal noise and noise of the device are much smaller than those of the type that is simply subjected to forging process, and the life of the reducer is one year. It has been confirmed that the period will be extended to about 15 years.

[0013]

[Effects of the Invention] Thus, according to the present invention, it is possible to minimize the abnormal sounds and noises of the equipment that are unavoidable in the forging process of slab strands, and it is possible to extend the life of the equipment and achieve stable operation. .

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a forging machine suitable for use in carrying out the present invention.

FIG. 2 is a side view of the device shown in FIG. 1;

FIG. 3 is an explanatory diagram of a forging process situation.

FIG. 4 is an explanatory diagram of the forging process situation.

FIG. 5 is a diagram showing the relationship between the load torque rate of the crankshaft and the load torque during forging.

FIG. 6 is a diagram showing the compression state of oil in the hydraulic cylinder during forging.

FIG. 7 is a diagram showing a situation when two slab strands are pressed.

FIG. 8 is a diagram showing a load torque curve when four slab strands are individually pressed.

[Explanation of symbols]

1a Anvil 1b Anvil 2 Mainframe 3 Subframe 4a Hydraulic cylinder 4b Hydraulic cylinder 5 Crankshaft 6 Balance cylinder 7 Displacement meter 8 Return cylinder S　Slab strand G Reducer M Drive source l1 Link l2 Link

Claims (2)

[Claims] Claim 1: A single crankshaft connected to a drive source via a reduction gear is rotated by preparing a plurality of pairs of anvils that sandwich a slab strand pulled out from a continuous casting mold on both sides. When performing continuous forging on the slab strands passing between the anvils by reciprocating movement of each anvil toward and away from each other by driving,
A continuous forging method for a slab toss land, characterized in that after forging by one set of anvils is completed and they are separated from each other, forging by another anvil is started at the stage when negative torque is generated. 2. The method according to claim 1, wherein the load torque of the crankshaft is set to a value that satisfies the following conditions. Tmin/TR ≧-0.5 Tmin: Minimum value of load torque TR: Rated torque of reducer