JPH0141452B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cutting a steel billet, and more specifically, the present invention relates to a method for cutting a steel billet, and more specifically, in a continuous billet, the temperature is higher on the upper surface side than the lower surface side, or the temperature on the upper surface side and the lower surface side is equal. Although there are some positions, generally the temperature is higher on the bottom side than on the top side, and the steel piece is cut by a pair of V-shaped or approximately V-shaped blades placed vertically opposite each other while holding the steel piece in between. The present invention relates to a cutting method.

For example, continuously cast steel pieces such as slabs and blooms that are continuously cast and extracted from a continuous casting machine are pulled downward from the mold of the continuous casting machine, pass through a curved conveyor section with a fixed radius of curvature, and then are transported horizontally. be done. Therefore, compressive stress is generated in the continuously cast steel billet in the surface portion in the direction of the center of curvature, and tensile stress is generated in the surface portion in the direction of the center of curvature in the curved conveyance portion. When the continuously cast steel billet reaches the horizontal conveyance section from this state, the surface portion in the direction of the center of curvature, that is, the top surface side, becomes tensile stress, and the surface portion in the direction of the center of curvature, that is, the bottom surface side, becomes tensile stress. This will change to compressive stress. Therefore, due to the tensile stress generated on the upper surface side of the continuous cast steel piece in the horizontal conveyance section, cracks are generated on the upper surface of the continuous cast steel piece, and internal cracks occur in the continuous cast steel piece.

Therefore, as a way to prevent this, for example, when the continuous cast steel slab reaches the horizontal conveyance section, cooling water is applied to the upper surface of the continuous cast steel slab to reduce the elongation strain caused by the tensile stress on the upper surface side. It will be done. For this reason, the temperature on the top side of the continuously cast steel billet is lower than the bottom side,
For example, the temperature on the upper surface side is 700 to 800 degrees Celsius, and the temperature on the lower surface side is 900 to 1000 degrees Celsius, and the temperature difference between the upper surface side and the lower surface side may be as much as 200 degrees Celsius.

As shown in FIG. 1, a piece of steel having such a temperature difference is pressed with a pair of, for example, V-shaped blades 1, 1, which are vertically opposed with a piece of steel 2 in between, with equal force, respectively.
When cutting the steel piece 2 by cutting into the steel piece 2 at high speed, the bottom side 2b of the steel piece 2 is higher in temperature than the upper side 2a, so the lower blade 1 cuts the steel piece more than the upper blade 1. Since the biting resistance against the piece 2 is small, the lower blade 1 bites into the steel piece 2 more as shown in FIG. This biting difference C is, for example, about 25 mm for a steel piece 2 having the above-mentioned temperature condition and having a thickness of 280 mm.

When such a phenomenon occurs, the steel billet 2 is conveyed on the conveyance roller 3 as shown in FIG. 3, and is cut while being supported on the conveyance roller 3 in the middle of this conveyance line. As a result, as shown in FIG. 3, the steel piece 2 is pushed down near the blade 1, and the conveying rollers 3a, 3b located on the left and right sides immediately adjacent to the lower blade 1 sandwich the lower blade 1. The rollers 3a and 3b are bent downward using the fulcrum as the fulcrum.
It becomes a state where it bites into. For this reason, especially
Conveyance rollers 3a, 3 located immediately to the left and right of the lower blade 1
The cutting force from the blade 1 acts directly on b through the steel piece 2. For this reason, the conveyance roller 3 may be damaged or damaged, and it is necessary to make the conveyance roller 3 itself strong. Furthermore, steel piece 2
There were also drawbacks such as roller impressions occurring on the roller itself, which diminished the value of the product. Also, like this,
If excessive bending is applied to the steel slab 2, it may cause distortion or defects in the unsolidified internal structure of the steel slab 2, reducing the product value, or excessive load may be applied to the pinch rolls of the continuous casting equipment. This hindered the stable extraction of slabs. In addition, in Figure 3, the symbol
PL represents the pass line of the steel billet 2, and the upper ends of all the conveyance rollers 3 are positioned on this pass line PL. Furthermore, each conveyance roller 3 is of a fixed type.

The present invention was developed in view of these drawbacks, and when a steel piece is cut by a pair of V-shaped or approximately V-shaped blades that are placed vertically opposite each other and sandwich the steel piece, the lower blade is cut. Nearby, above the pass line of the steel billet, the steel billet was cut while maintaining a desired gap between the lower surface of the steel billet and the pass line of the steel billet.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

First, a first example will be described.

In the embodiment shown in FIG. 4, while cutting the steel piece 2 whose temperature is generally higher on the lower side 2b than on the upper side 2a, the lower surface level LL of the steel piece 2 near the lower blade 1 is always cut.
is detected by two level detection rollers 4, 4 located on the left and right sides of the lower blade 1 as a level detection device, and by controlling the absolute speed of the upper blade 1 and the lower blade 1, the A method of cutting a steel billet in which the gap A between the lower surface level LL of the steel billet 2 and the pass line PL of the steel billet 2 is kept almost constant during cutting, and cutting force is not applied to the conveyance roller 3 will be explained. It is something to do.

This method can be applied to one cutting device to which the present invention is applied.
This will be explained based on FIG. 5, which shows an example.

First, to explain the structure of this cutting device 5, an upper blade platen 7, a lower blade platen 8, and a bottom platen 9 are provided inside the main body frame 6 from top to bottom, and are movable up and down with respect to the main body frame 6. Furthermore, the upper blade platen 7 and the bottom platen 9 are integrally connected by a tie bar 10 that is slidably penetrated through the lower blade platen 8. On the other hand, the lower blade platen 8 is connected to a cutting ram 11 built in a ram chamber 11a provided in the bottom platen 9.
Furthermore, a holding cylinder 14 is connected between the bottom platen 9 and the lower part of the main body frame 6.
is interposed, and its piston rod 14a is connected to the bottom platen 9. Further, a pullback cylinder 15 is provided between the lower blade platen 8 and the bottom platen 9. Further, V-shaped blades 1, 1, which are an example of a cutter according to the present invention, are respectively attached to the upper blade platen 7 and the lower blade platen 8 so as to face each other with a piece of steel 2 in between. Steel piece 2
Level detection rollers 4, 4 are provided on the left and right sides of the lower blade 1, and each of the level detection rollers 4, 4 is a clevis type whose one end is rotatably attached to the main body frame 6. It is rotatably attached to the tip of the piston rod of the cylinder 12 from diagonally below, and supported diagonally from above by a connecting member 13 such as a turnbuckle whose one end is rotatably supported on the main body frame 6. Therefore, each level detection roller 4, 4 is connected to the cylinder 1.
By expanding and contracting the piston rod 2, the attachment fulcrum 13a of the connecting member 13 to the main body frame 6 is fixed.
Move freely around the center.

Level detection rollers 4, 4 configured in this way
is brought into contact with the lower surface 2b of the steel piece 2 to be cut in a state where it is lifted upward by a desired amount in the vicinity of the lower blade 1, as shown in FIG. The amount of displacement in the vertical direction of the lower surface 2b of 2 is constantly detected. At this time, cylinder 12
A pressure sufficient to bear the weight of the steel piece 2 is applied to the head side of the steel piece 2. Then, the speed of the piston rod 14a of the holding cylinder 14 is controlled in accordance with the amount of displacement of the lower surface 2b of the steel piece 2.
In addition, by having such a configuration, the level detection rollers 4, 4 can be used in the event that the cutting force of the upper blade 1 is applied and the steel piece 2 is pushed downward due to a malfunction or the like during cutting. , since it is pushed downward accordingly, it can also function as a so-called depressing roller, which is safe.

In addition, by extending the piston rod of the cylinder 12, it is also possible to cause the steel piece 2 near the blade 1 to be lifted upward, for example. Further, since the level detection rollers 4, 4 are rotatably attached to the piston rod of the cylinder 12 and the connecting member 13, when the steel piece 2 is not cut, the upper ends of the level detection rollers 4, 4 are passed. By aligning it with the line PL, it functions as a conveyance roller for the steel billet 2.

On the other hand, fixed conveyance rollers 3 for a plurality of steel pieces 2 are provided on the left and right sides of the level detection rollers 4, 4, with their upper ends aligned with the pass line PL of the steel pieces 2.

Using the cutting device 5 configured as described above, cutting is performed in the following manner.

When the steel piece 2 being conveyed comes to the position where it is to be cut, the drive of the conveyance roller 3 is stopped and the steel piece 2 is stopped on the conveyance roller.

In this state, first, the cylinders 12, 12 for the left and right level detection rollers 4, 4 that sandwich the lower blade 1 are operated in synchronization, and both level detection rollers 4, 4 are lifted upward by an equal amount, and the lower blade Slab 2 near 1
is lifted by the desired amount A from the pass line. This lifting amount A is, for example, approximately 10 mm for a steel slab 2 with a plate thickness of 280 mm, so that the steel slab 2 is not subjected to distortion or internal defects due to bending action, and also has an accurate holding cylinder as described later. It is desirable to make the speed as small as possible within the range where speed control of 14 is possible.

Next, with respect to the steel piece 2 that has been lifted by a desired amount A in the vicinity of the lower blade 1 as described above, the upper blade 1 and the lower blade 1 are placed in vertically symmetrical positions with the steel piece 2 in between. . At this time, the holding cylinder 14 and the pullback cylinder 15 are used.

Cutting is started in this state. First, the cutting ram cylinder 11 is activated to raise the lower blade 1 relative to the bottom platen 9 at a speed of v.
At the same time, the holding cylinder 14 is activated and its piston rod 14a is lowered at a speed of v/2.

As a result, the upper blade 1 will descend at a speed of v/2, and the lower blade 1 will rise at a speed of v-(v/2)=v/2. Therefore, the upper blade 1 and the lower blade 1 descend and rise at the same speed v/2, respectively.

In this way, the upper blade 1 and the lower blade 1 each start to bite into the steel slab 2, but for the steel slab 2 whose lower surface side 2b is higher in temperature than the upper surface side 2a, the upper surface side 2a and the lower surface side of the steel slab 2 2b and the cutter 1 have different biting resistance, and this resistance is smaller on the lower surface side 2b.
Therefore, as the cutter 1 bites, the lower blade 1 bites into the piece of steel 2 more than the upper blade 1, so the piece of steel 2 lifted near the blade 1 is pushed down, and the initial setting is Lifting amount setting value A
becomes less.

When this happens, the level detection rollers 4, 4, which are in contact with the lower surface 2b of the steel piece 2, descend as the steel piece 2 descends. Then, in accordance with this descending amount, the descending speed v/2 of the piston rod 14a of the holding cylinder 14 is decreased by a desired amount α. That is, the speed of the holding cylinder 14 is controlled so that the absolute downward speed of the upper blade 1 becomes (v/2)-α. At this time, the rising speed v of the cutting ram 11 relative to the bottom platen 9 is always kept constant. Therefore, as mentioned above, if the descending speed of the upper blade 1 decreases by α, the ascending speed of the lower blade 1 increases by α, the absolute ascending speed of the lower blade 1 becomes (v/2) + α, and the upper blade 1 increases by α. 1 and the lower blade 1 is always a constant speed v. Note that in order to adjust the speed of the upper and lower blades 1, 1, the speed of the cutting ram cylinder 11 can be controlled, but since this cutting ram cylinder 11 exerts a large cutting force, the cylinder is large. Therefore, it is difficult to control the speed reliably, and it is generally easier to control the speed reliably with the holding cylinder 14, which may be a cylinder with a small capacity.

In this way, by reducing the biting speed of the upper blade 1 and increasing the biting speed of the lower blade 1, the downward descent of the steel piece 1 is prevented. Such control is always performed during cutting, and the steel piece 2 is cut while keeping the initially lifted amount A substantially constant. Therefore, no cutting force is applied to the conveying roller 3 via the steel piece 2. and,
The upper blade 1 and the lower blade 1 bite into the steel piece 2 and the cutting is completed, but at the time the cutting is completed, the upper surface side 2a under the above-mentioned temperature conditions is, for example, 700 to 80 degrees Celsius.
For a steel piece 2 with a thickness of 280 mm, where the lower surface side 2b is 900 to 1000 degrees Celsius and the temperature difference between the upper surface side 2a and the lower surface side 2b is 200 degrees Celsius, the biting difference C between the upper and lower blades 1, 1 is still approximately It will be 25mm. Note that FIGS. 4 and 5 show the state immediately before the cutting is completed.

When the cutting is completed, the holding cylinder 14
Then, by operating the pullback cylinder 15 to separate the upper blade 1 and the lower blade 1 from the steel piece 2, and then gradually lowering the two level detection rollers 4, 4, the upper blade 1 and the lower blade 1 are lifted near the blade 1. The cut steel piece 2 is lowered, the lower surface 2b of the steel piece 2 is returned to the pass line, and the conveyance roller 3 is driven to send the cut steel piece 2 to the next process. Then, the uncut steel pieces 2 are sent to the position where they are to be cut, and the same cutting operation is performed to sequentially cut the steel pieces 2.

Note that the method described above is a cutting method mainly aimed at cutting steel slabs 2 whose lower surface side 2b is higher in temperature than the upper surface side 2a; In this case, the bottom side 2b
is higher than the upper surface side 2a, but at a certain position in the longitudinal direction, although less frequently, the upper surface side 2a is higher than the lower surface side 2b, or the upper surface side 2a and the lower surface The temperatures on sides 2b may become equal. For example, top side 2
When cutting at a position where the temperature of a is higher than that of the lower surface side 2b, the upper blade 1 bites into the steel piece 2 more than the lower blade 1, contrary to the above, and this As a result, the steel piece 2 comes to be lifted upward. Therefore, in this case, upper blade 1 and lower blade 1
The speed is controlled as follows.

First, at the start of cutting, the two level detection rollers 4,
4 upward, and lift the steel piece 2 upward by a desired amount A (for example, 10 mm) near the lower blade 1.
In this state, using the holding cylinder 14 and the pullback cylinder 15, the upper blade 1 and the lower blade 1 are placed in vertically symmetrical positions with the steel piece 2 sandwiched between them. Then, similarly to the above, the cutting ram 11 is raised upward at a speed of v, and the piston rod 14a of the holding cylinder 14 is lowered at a speed of v/2. That is, the upper blade 1 and the lower blade 1 are respectively lowered and raised at the same speed v/2 to start cutting. As the double blades 1 and 1 bite into the steel piece 2, the steel piece 2, which was initially lifted by the amount A near the lower blade 1, is further lifted upwards, and the level detection roller follows this. 4,4 will also move upward. When the initially set lifting amount A is exceeded, the rising speed v of the cutting ram 11 is increased.
is constant, and contrary to the above, the holding cylinder 14
The absolute descending speed of the piston rod 14a is made faster than the initial setting value A by an amount commensurate with the amount of lifting that exceeds the above-mentioned initial setting value A. That is, the speed of the holding cylinder 14 is controlled so that the absolute downward speed of the upper blade 1 becomes (v/2)+β. As a result, the absolute rising speed of the lower blade 1 becomes (v/2)-β. In this way, when cutting at a position where the temperature of the steel piece 2 is higher on the upper surface side 2a than on the lower surface side 2b, the biting speed of the upper blade 1 is increased during cutting, and the biting speed of the lower blade 1 is increased. By making the steel piece 2 smaller, the lifting phenomenon of the steel piece 2 is prevented, and the steel piece 2 is cut while keeping the gap between the lower surface level LL of the steel piece 2 and the pass line PL substantially constant near the lower blade 1.

On the other hand, even when cutting at a position where the upper surface side 2a and the lower surface side 2b are at the same temperature, the steel piece 2 is lifted by a desired amount A at the beginning of cutting.

Note that when cutting the steel piece 2 at a position where the temperature on the upper surface side 2a is higher than on the lower surface side 2b, the steel piece 2 is automatically lifted upward during cutting, while the upper surface side 2a and the lower surface side When cutting at a position where the temperature of the side 2b is equalized, the piece of steel 2 does not move, so it may not be necessary to perform such control. This eliminates the need to complicate the operational control method for the cutting equipment, allows for more reliable control, and prevents the steel billet from being pushed downwards due to an abnormal load due to malfunction of the equipment, etc. Even if the conveyance roller 3 becomes unintentional, it is possible to more reliably prevent cutting force from acting on the conveyance roller 3.

In this way, by controlling the absolute speed of the upper blade 1 and the lower blade 1 while keeping the relative speed of the upper blade 1 and the lower blade 1 constant, it is possible to always maintain the position near the lower blade 1 during cutting. If the steel slab 2 is cut so that the gap between the lower surface level LL and the pass line PL is kept almost constant, the temperature of the steel slab 2 will generally be higher on the lower surface side 2b than on the upper surface side 2a, but in this case But, or the position where this is reversed, or the top side 2
Even when cutting is performed at a position where the temperatures of a and the lower surface side 2b are equal, it is possible to deal with any case.

Next, a second example will be described.

This method does not use the level detection rollers 4, 4 as described above, but uses a temperature detection device for the steel piece 2, etc. to detect the upper surface side 2a and the lower surface side 2b of the steel piece 2 in the vicinity of the lower blade 1. Detects the actual temperature of the steel plate, predicts and calculates the amount of penetration of the upper blade 1 and lower blade 1 into the steel piece 2 according to this temperature, and similarly calculates the gap between the lower surface level LL of the steel piece 2 and the pass line PL. The speed of the lower blade 1 and the upper blade 1 is controlled so that the cutting speed is kept almost constant.

As an example of a cutting device in this case, in the cutting device 5 shown in FIG. The pass line PL
It is fine if it matches. Temperature detection devices (not shown) for detecting the temperatures of the upper surface 2a and the lower surface 2b of the steel piece 2 are then installed near the upper blade 1 and the lower blade 1 of the main body frame 6 of the cutting device 5 by narrowing the steel piece 2, respectively. The actual surface temperature of the upper surface 2a and lower surface 2b of the steel piece 2 at the position to be cut is detected, and the upper blade 1 and the lower blade 1 bite into the steel piece 2 corresponding to the surface temperature conditions of the upper and lower surfaces. By inputting this surface temperature to a calculation device (not shown) that predicts and calculates the amount, a speed control command is issued from the calculation device to the holding cylinder 14 in accordance with the biting amount of the upper blade 1 and the lower blade 1, During cutting, for example, keep the relative speed of the upper blade 1 and lower blade 1 constant so that the gap between the lower surface level LL of the steel piece 2 and the pass line PL is almost constant near the lower blade 1. The absolute speeds of the blade 1 and the lower blade 1 are controlled under conditions commensurate with the surface temperature of the steel piece 2.

It should be noted that the arithmetic unit is equipped with various upper blades 1 that are suitable for the temperatures of the upper surface side 2a and lower surface side 2b of the steel piece 2 in advance.
and the amount of biting into the steel piece 2 by the lower blade 1.

That is, for example, when the temperature of the steel billet 2 is higher on the lower surface side 2b than on the upper surface side 2a, the lower blade 1 will bite into a larger amount, and as a result, the steel billet 2 will descend downward. Therefore, the absolute ascending speed of the lower blade 1 is controlled to be greater than the absolute descending speed of the upper blade 1, so that the lower surface of the steel piece 2 is always level with the steel piece 2 during cutting.
The gap between LL and pass line PL should be kept almost constant. In this way, it is possible to prevent the cutting force from acting on the conveyance roller 3 via the steel piece 2 during cutting.

Note that in both the first and second embodiments above, the case where the relative speed of the upper blade 1 and the lower blade 1 is kept constant and the absolute speed of the upper blade 1 and the lower blade 1 is changed has been described, but of course , but is not limited to this case. For example, while changing the relative speed between the upper blade 1 and the lower blade 1, that is, while changing the cutting speed, the upper blade 1
It is also possible to control the absolute speed of the lower blade 1 to be changed.

Next, a third embodiment will be explained based on FIGS. 5 to 7.

In this method, generally speaking, the lower surface side 2b is better than the upper surface side 2b.
When starting to cut a steel piece 2 whose temperature is higher than that of a, at least the difference in the biting amount of the blades 1, 1 due to the temperature difference between the upper surface side 2a and the lower surface side 2b in the vicinity of the lower blade. Only C has the lower blade 1 and the steel piece 2.
, and bring the upper blade 1 into contact with the upper surface side 2a of the steel piece 2 in this state, that is, in the state shown in FIG. 6, and lower and raise the upper blade 1 and the lower blade 1 at the same speed, respectively. The steel piece 2 is cut using the following steps.

As an example of a cutting device applied to this method, in the cutting device 5 shown in FIG.
As described in the embodiment, the upper ends of both level detection rollers 4, 4 are aligned with the pass line PL to form a fixed conveyance roller 3.

This cutting method will be explained based on such a cutting device 5.

At the beginning of cutting, first, as shown in FIG. 7, the distance L ₁ between the tip of the upper blade 1 and the upper surface 2a of the steel piece 2 is 2b
The distance L ₂ from the steel plate 2 to the steel plate 2 should be at least twice the value 2C of the difference C between the biting amount of the upper and lower blades 1, 1 due to the temperature difference between the upper surface side 2a and the lower surface side 2b of the steel piece 2. The positions of the upper blade 1 and the lower blade 1 are set with respect to the steel piece 2.

The setting procedure for the upper and lower blades 1, 1 at this time is, for example, when the piston rod 14a of the holding cylinder 14 is at the upper stroke end, as shown in FIG.
Alternatively, the cutting ram 11 may be located near the upper stroke end, while the cutting ram 11 may be located at the lower stroke end or near the lower stroke end.

Then, in the state shown in FIG. 7, the cutting ram 1
1 relative to the bottom platen 9 at a speed v, and at the same time the piston rod 1 of the holding cylinder 14
4a is lowered at a speed of v/2. In this way, the upper blade 1 and the lower blade 1 will descend and rise at the same speed v/2, respectively. Then, the upper blade 1 and the lower blade 1 each advance toward the steel piece 2, and when the lower blade 1 rises by a distance L ₂ , the tip of the lower blade 1 hits the lower surface side 2b of the steel piece 2. When the upper blade 1 touches the steel piece 2 and then lifts the steel piece 2 upward from the pass line PL near the lower blade 1 by a distance C, the upper blade 1 touches the steel piece 2.
abuts against the upper surface 2a of the. The state at this time is shown in FIG.

From this state, the upper blade 1 and the lower blade 1 begin to bite into the steel piece 2, and cutting is started. Then, the lower blade 1 bites into the steel piece 2 whose temperature is higher on the lower side 2b than on the upper side 2a, and as the cutting progresses, the steel piece 2 initially lowers. The amount C lifted by blade 1 gradually decreases,
It's being pushed downwards. When the cutting is completed, the lower surface 2b of the steel piece 2 returns to the pass line PL. Therefore, during cutting, the lower blade 1 is always
Since the cutting can be performed while maintaining a gap between the lower surface level LL of the steel slab 2 and the pass line PL in the vicinity of , the cutting force is prevented from acting on the conveyance roller 3 via the steel slab 2. It can be prevented.

The amount by which the steel piece 2 is lifted near the lower blade 1 at the beginning of cutting is determined by the biting difference C between the upper and lower blades 1.
It will be safer if a desired margin is given to (as mentioned above, for example, 25 mm), such as C+10=25+10=35 mm. Also, this margin is
It is preferable to set the amount to be as small as possible to reduce the adverse effects of bending on the steel billet 2, and to minimize the impact of impact load, etc. on the conveyance roller 3 when the steel billet 2 falls after cutting is completed. .

Furthermore, even when cutting a continuous piece of steel 2 at a position where the temperature on the upper surface side 2a is higher than on the lower surface side 2b, or when cutting at a position where the temperature on the upper surface side 2a and the lower surface side 2b are equal. Even if this happens, the frequency is low, so if the steel piece 2 is always lifted upwards by the lower blade 1 at the beginning of cutting as described above, the operation method will be simplified. good.

Although the blade in the embodiment described above takes the V-shaped blade 1 as an example, the blade according to the present invention is not limited to this, and for example, a V-shaped blade as shown in FIGS. Or approximately V-shaped single-stage blade 20~2
3 or multistage blades 24 to 27 may be used.

Further, as an example of a cutting device to which the present invention is applied, there is a so-called fixed type cutting device 5 that stops the steel piece 2 at a cutting position and cuts the steel piece 2, as shown in FIG. Although described above, the cutting device applied to the present invention is not limited to this, and for example, while conveying the steel billet 2, it may synchronize with the conveyance speed of the steel billet 2, or control the traveling speed appropriately. It may be a so-called running type cutting device that cuts the steel piece 2 while moving the cutting blades 1, 20-27.

As is clear from the above description, the present invention provides a method for cutting a steel piece in the vicinity of the lower blade when cutting the steel piece with a pair of V-shaped or approximately V-shaped blades arranged vertically opposite each other while sandwiching the steel piece. Since the steel piece is cut while maintaining the desired gap between the lower surface of the steel piece and the pass line of the steel piece above the pass line of the steel piece, the cutting force of the blade acts on the conveying roller during cutting. This phenomenon can be prevented.

Therefore, breakage and damage to the conveyance rollers can be eliminated, smooth operation can be achieved, and operation efficiency can be improved. Then, there is no need to make the conveyance rollers more sturdy than necessary.

Furthermore, since excessive bending is not applied to the steel billet, there is no possibility of causing defects to the internal structure of the steel billet, which is still unsolidified due to high temperatures, and also to the steel billet itself. Since there are no impressions caused by rollers, the value of the product is not impaired, and products of stable quality can be obtained.

Furthermore, when the present invention is applied to a running-type cutting device installed immediately behind a continuous casting device, for example, an excessive load will not be applied to the pinch rolls, etc. at the end of the continuous casting device. Therefore, stable continuous casting is possible.

From the above, the advantages of cutting a piece of steel with a pair of V-shaped or approximately V-shaped blades can be fully exploited. In other words, the cut portion is preformed into a tapered shape at the same time as it is cut, and the cutting burr is generated near the center in the thickness direction, so when the cut steel piece is rolled by rolling rolls, the product is It is possible to reduce the amount of irregularly shaped portions, so-called cropping, occurring at the front and rear ends, and to reduce the amount of bald spots, contributing to an improvement in product yield.

In addition, since the cutting part is tapered, there is no need to poke the conveyance roller when the cut steel piece is conveyed by the conveyance roller, and the resistance to biting into the rolling roll is also improved, making operation even easier. Efficiency can be improved.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the conventional cutting method, Figure 2 is a diagram explaining the conventional cutting method;
The figures are diagrams explaining the difference in biting between the upper and lower blades when cutting by the conventional method, Figure 3 is a diagram explaining the state of the steel billet when it is cut by the conventional cutting method, and Figure 4 is a diagram explaining the state of the steel billet when it is cut by the conventional cutting method. The figures are diagrams illustrating one embodiment of the present invention,
FIG. 5 is a front view (partial sectional view) showing one example of a cutting device applied to the present invention, FIG. 6 is a diagram illustrating another embodiment of the present invention, and FIG. FIG. 8, which is a supplementary explanation of the embodiment shown in FIG. 6, shows another embodiment of the blade according to the present invention. DESCRIPTION OF SYMBOLS 1,20-27... V-shaped or substantially V-shaped blade, 2... Steel piece, 3... Conveyance roller, 4... Level detection roller, 5... Cutting device, 7... Upper blade platen, 8... ...Lower blade platen, 9...Bottom platen, 11...Cutting ram, 14...Holding cylinder, PL...Pass line, LL...Bottom surface level of steel piece.

Claims (1)

[Claims] 1. When cutting a steel billet with a pair of V-shaped or approximately V-shaped blades arranged vertically opposite each other while sandwiching the steel billet, the path line of the steel billet is cut in the vicinity of the lower blade. A method for cutting a steel billet, characterized in that the steel billet is cut while maintaining a desired gap between the lower surface of the steel billet and a pass line of the steel billet above. 2. While cutting a steel piece, the level of the bottom surface of the steel piece near the lower blade is constantly detected by a level detection device, and by controlling the absolute speed of the upper and lower blades, the lower surface level of the steel piece is detected near the lower blade. 2. The method for cutting a steel billet according to claim 1, wherein the steel billet is cut while keeping a substantially constant gap between the steel billet and the pass line of the steel billet. 3. While cutting the steel piece, the temperature on the upper and lower sides of the steel piece is detected by a temperature detection device.
By using a calculation device to predict and calculate the amount of penetration of the upper and lower blades into the steel piece, and by controlling the absolute speeds of the upper and lower blades, the path between the lower surface of the steel piece and the piece of steel is adjusted in the vicinity of the lower blade. 2. The method for cutting a steel billet according to claim 1, wherein the steel billet is cut while keeping a substantially constant gap between the steel billet and the line. 4 When starting cutting, near the lower blade,
Lift the piece of steel with the lower blade by at least the difference in the amount of penetration between the upper and lower blades, and in this state, bring the upper blade into contact with the top surface of the piece of steel, and move the upper and lower blades at the same speed. A method for cutting a steel piece according to claim 1, characterized in that the steel piece is cut by biting into the steel piece.