JPH10510A - Steel bar cutting method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To suppress variations in the excess length of a steel bar product due to backlash or the like of a shearing machine. SOLUTION: In a method for cutting a steel bar product in which a rolled steel bar is cut into a standard product length by a shearing machine 5 and a surplus length of the cut steel bar product 9 is controlled to a preset length, a shearing machine 5 is provided. The set cutting length is tracked together with the cut steel bar product 9, and when the steel bar product 9 reaches the transfer table 7, which is downstream equipment of the shearing machine 5, the temperature and the length are measured, and based on the measurement result, By calculating the surplus length at room temperature, the difference from the set surplus length is obtained, and the set cut length is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cutting a steel bar product for setting a surplus length of a steel bar product after cooling to a target value when cutting a hot steel bar into a product length.

[0002]

2. Description of the Related Art A steel bar is heated to a predetermined temperature in a heating furnace, then rolled into a predetermined shape and size by a rolling mill, and then sent to a cooling floor by a roller table to be cooled. . In recent bar and steel mills, depending on the weight of the material and the dimensions of the product, the heavy material is used, so that the product becomes extremely long and cannot be handled on a cooling floor as it is. For this reason, the finish-rolled steel bar is divided and cut into appropriate lengths by a division cutting machine installed immediately after the finish rolling mill. Therefore, several bars are produced from one billet.

[0003] The steel bar sent to the cooling floor is usually allowed to cool, and then conveyed to the next step, a fixed-size shearing step. In the standard-shearing process, several pieces of the cooled steel bars are cut together to the specified product length, and the specified product length is specified in the form of the target product length and its tolerance. This tolerance is the extra length. In actual operation, the product cannot be shipped as a product unless the target product length is absolutely secured at room temperature.

[0004] However, the bar temperature at the time of cutting a fixed length is
Even if it is allowed to cool, it is usually 300 to 400 ° C. For this reason, it is necessary to consider the shrinkage allowance at normal temperature when setting the cutting length of the standard-size shearing machine, and correct the length to allow for the shrinkage allowance according to the bar steel temperature at the time of standard-size cutting. ing. An example of the calculation formula is shown below. _{L H = L c + (L} c + L A) α · T c + L A , however, L _c: target length at room temperature (m), L _H: hot cut length setpoint (m), T _c: steel bar temperature during cutting (℃), α: linear expansion coefficient of the steel (deg ^-1), L _a: extra length (m),

[0005] The length control of the steel bar in the above-mentioned standard-shearing machine is performed by an operator by actually measuring and confirming the product length on a transfer table, which is a downstream process of the standard-shearing process, and setting the cutting length based on the actual measurement. The value has been corrected. Therefore, in this method, the shearing machine line is stopped until the actual measurement result of the product length is found. At present, there is a problem that efficiency is low in terms of productivity.

As a countermeasure, when the hot steel is cut to a target length after cooling, the temperature of the steel is measured or predicted,
A method of setting the cutting length by correcting the amount of thermal expansion in consideration of the change in the coefficient of linear expansion accompanying the transformation of steel (Japanese Patent Laid-Open No. 57-14 / 1982)
No. 4619).

[0007]

In the case where the set value of the cutting length of the shearing machine is adjusted by actually measuring the length of the cut steel bar product, when the operator actually measures the product length on the transfer table. Since the upstream process must be stopped, the product length cannot be frequently measured from the viewpoint of productivity. In addition, since the actual measurement of the product length is performed at the beginning of normal work, the elongation length of the bar changes depending on the product temperature, steel type, etc. with the passage of time, so the variation in excess length increases,
The extra length is set longer. As a result, the yield of the steel bar product is reduced.

The method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Sho 57-144619 sets the cutting length of the shearing machine by correcting the amount of thermal expansion in consideration of the change in the coefficient of linear expansion accompanying the transformation of steel. This is a hot cutting at a cutting temperature of 600 to 720 ° C., and it cannot be directly applied to the cutting of a steel bar which does not need to consider the change in the coefficient of linear expansion accompanying the transformation of steel. No confirmation has been made of the actual cut length of the cooled steel material after cooling. For this reason, in an actual shearing facility, there is a problem that the set value is not satisfied due to backlash of a shearing machine or the like. In other words, although the cutting length has a small variation, it cannot be confirmed whether the extra length to be added is a set value.

An object of the present invention is to provide a method for cutting a steel bar product which can solve the above-mentioned disadvantages of the prior art and can suppress the variation of the excess length of the steel bar product due to backlash of a shearing machine or the like.

[0010]

SUMMARY OF THE INVENTION The present invention tracks the set cutting length of a shear with a cut steel bar product and determines the temperature and temperature when the steel product reaches a transfer table which is downstream equipment of the shear. The length is measured, the surplus length at normal temperature is calculated based on the measurement result, the difference with the set surplus length is obtained, and the set cut length is corrected. In this way, when the steel bar product reaches the transfer table, which is downstream equipment of the shearing machine, it measures the temperature and length, calculates the extra length at room temperature based on the actual measurement result, and calculates the difference from the set extra length. , And correcting the set cutting length, the length of the steel bar product can be measured without stopping the transfer line, and the production efficiency is not reduced. Further, the variation in the extra length of the steel bar product due to the play of the shearing machine can be suppressed, and the cutting can always be performed with the optimal extra length, so that the steel bar yield can be improved.

[0011]

In DETAILED DESCRIPTION OF THE INVENTION The present invention, on the basis of the temperature T _i and the length H _i of steel bar products that are actually measured on the transfer rack, first following the product length L _i at room temperature of the steel bar products ( 1) It is determined by the equation. _{L i = H i -L i ·} α i · T i ... (1) Equation However, L _i: the length of the product i at room temperature (m), H _i: the measured length of the product i at a temperature T _i ( m), T _i : measured temperature (° C.), α _i : coefficient of linear expansion of product i (deg ⁻¹ )

Next, the optimum length of the product i (the target product length S
_i + optimal excess length beta _i) and the product i at room temperature of (1) reacting a surplus length .beta.a _i can be reduced from the length L _i computed by the following equation (2). _{βa i = L i - (S} i + β i) ... (2) Equation However, .beta.a _i: excess length can be reduced product i at room temperature (m), S _i: target length of the product i at room temperature (m ), Β _i : optimal extra length (m) of product i at normal temperature,

Therefore, the next set cutting length H _{(i + 1)} of the shearing machine can be obtained by the following equation (3) when the steel type is the same. H _{(i + 1)} = H _i −βa _i · (1 + α _i ) · T _i (3) where H _{(i + 1) is the} next set cutting length (m), H _{i is the} current setting Cutting length (m)

H _{(i + 1)} obtained by the above equation (3) is set as the cutting length of the shearing machine. Further, if the steel type of the bar steel product measured on the transfer table and the steel bar to be cut by the shearing machine are different, the coefficient of linear expansion changes, so the above equation (3) is corrected to the following equation (4). H _{(i + 1)} = H _i −βa _i · {1 + min (α _i , α _{i + 1} )} · T _i (4) where α _{i + 1} is the linear expansion coefficient (deg ^{− 1} )
The smaller of the linear expansion coefficients (α _i , α _{i + 1} ) is adopted to increase the safety factor.

According to the present invention, by correcting the set cutting length of the shearing machine as described above, the surplus length of the steel bar product can always be controlled to the optimum extra length, and the yield of the steel bar product can be improved.

The measurement of the length of the bar on the transfer table in the present invention is based on the fact that the tip of the bar on the transfer table is located at a substantially constant position by a stopper, and the rear end position changes depending on the product length of the bar. Two industrial television (ITV) cameras that gaze at the transfer table from above are fixed at one of the ITV camera positions at the tip of the steel bar product, that is, at the stopper position, and the other ITV camera is mounted at the product length of the steel bar. When the steel bar product comes to the measurement position, images of both ends of the product are taken by two ITV cameras, respectively, and image processing is performed to recognize both end positions. The product length of the steel bar is measured from the result and the positional relationship between the two ITV cameras. Both of the two ITV cameras can be movable, and may be a photoelectric system, for example, a laser system instead of image processing, which may be selected according to equipment conditions.

In the present invention, the temperature of the steel bar on the transfer table is measured by installing a non-contact type temperature detector such as a radiation thermometer or a contact type temperature detector such as a resistance thermometer or a thermocouple to measure the temperature of the steel bar. I do.

The measurement operation of the ITV camera and the temperature detector is controlled by a measurement control device. The measurement control device and the shear control unit are connected by a communication line, and the tracking information and the measurement result of the steel bar product to be measured are mutually input and output. The shear control unit tracks the steel bar cut by the shearing machine, and the product length of the steel bar input from the measurement control device,
Wherein the temperature (1) and (2) determine the extra length .beta.a _i possible reduction on the basis of equation (3) above seek next set cut length H _{(i + 1)} based on the equation, setting the cut length That is, _Hi is corrected.

The length and temperature of the steel bars are measured on the transfer table, but they can be installed immediately after the shears. In this case, the correction timing of the set cutting length with respect to the shearing machine has a better real-time property as compared with the case where measurement is performed on the transfer table.

[0020]

【Example】

Embodiment 1 The details of a method for cutting a steel bar product of the present invention will be described below with reference to FIGS. 1 and 2 showing an embodiment. FIG. 1 is an overall schematic layout view of a steel bar product cutting facility of the present invention, and FIG. 2 is a block diagram of a steel bar product cutting method of the present invention.

In FIG. 1, reference numeral 1 denotes a bar rolling mill, 2 denotes a roller table for transporting a steel bar finished and rolled to a predetermined shape and dimensions by a bar rolling mill 1 to a cooling floor 3 for cooling. A roller table for transporting a plurality of steel bars cooled to 300 to 400 ° C. on the cooling floor 3 to a shearing machine 5 for cutting to a set cutting length, and 6 is cut by the shearing machine 5 to a set cutting length. Roller tables 8a and 8b for transferring the steel bars to the downstream transfer table 7 are provided with two ITs for measuring the length of the steel bar products 9 on the transfer table 7 provided above the transfer table 7.
The V camera 10 is a temperature detector for measuring the temperature of the bar product 9 on the transfer table 7.

[0022] In FIG. 2, 21 measurement control unit for detecting a product length H _i and the temperature T _i of the steel bar products 9 controls the measurement operation of the ITV cameras 8a, 8b and the temperature detector 10 of FIG. 1, 22 Is a shear control unit, which is connected by a communication line to a shear control device 23 for operating the shears 5 and a measurement control device 21, outputs tracking information of the steel bar product 9 to be measured to the measurement control device 21, and performs measurement control. Device 21
Length H _i and temperature T _{i of} the steel bar product 9 detected from
Is configured to be input. Also, the shear control unit 2
2, based on the product length H _i and the temperature T _i of the steel bar products 9 which is input from the measurement control unit 21, the (1) -
(2) determine the extra length .beta.a _i possible reduction on the basis of equation, the equation (3) or (4) obtains the next set cutting length H _{(i + 1)} based on the equation, setting the cutting length H It is configured to cut the steel bar by correcting _i .

With the above-described configuration, the shear control unit 22 tracks the position of the steel bar product 9 cut by the shearing machine 5 and, when the steel bar product 9 is conveyed onto the transfer table 7, the measurement control unit 21. Output the measurement command. When a measurement command is input from the shear control unit 22, the measurement control device 21 changes the ITV cameras 8 a and 8 b and the temperature detector 1 in FIG.
0 is operated to actually measure the product length and the temperature of the steel bar product 9, and output the measured product length and the measured temperature to the shear control unit 22.

[0024] measured product length of steel bar products 9i H _i and the measured temperature T _i is inputted shear control unit 22, first the (1) the length of the product at room temperature steel bar products 9i based on equation L _i is determined, and then the optimum length of the steel bar product 9i (target length +
The extra length .beta.a _i can be reduced optimally excess length) and the product at room temperature from a length L _i (2) calculated based on formula, the next time of setting the cutting length _{H (i + 1) (3} ) Computation is performed based on the equation to correct the set cutting length of the shears 5.

When the steel bar product 9 measured on the transfer table 7 and the steel bar of the steel bar to be cut by the shearing machine 5 are different from each other, the linear expansion coefficient is different.
_{(i + 1)} is calculated based on the above equation (4), and the set cutting length of the shearing machine 5 is corrected. Therefore, the product length of the steel bar product 9 can be measured without stopping the transport line, and the surplus length of the steel bar product 9 is grasped in real time and fed back to always add the optimum excess length to the steel bar product. And the yield can be improved.

[0026] and method of the present invention described in Example 2 above Example 1, the steel bar temperature during fixed-length cut as a conventional _{method, L p = L + (L} + L A) · α · T c) + L A , however, L: target length at room temperature (m), L _p: cut length setpoint (m), T _c: bar steel temperature at the time of cutting (℃), α: linear expansion coefficient of the steel (deg ^-1), L _a: The bar for reinforced concrete was cut in each case where the length was corrected to allow for the shrinkage allowance based on the extra length (m). In that case, the product length and excess length at room temperature and the yield of the steel bar product were measured. Table 1 shows the results. JIS
Since the tolerance in the standard is 0 to +40 mm, the surplus aiming margin is 20 mm.

[0027]

[Table 1]

As shown in Table 1, in the case of the method according to the present invention, the surplus length is 10 to 3 around the surplus length of 20 mm.
0 mm, the surplus length can be secured almost optimally, and the yield of the steel bar product is 93.90%, whereas in the case of the conventional method, the surplus length is between 20 and 45 mm centering on 30 mm. It is not possible to manage to the optimal extra length,
As a result, the yield of the steel bar product was 92.46%.

[0029]

According to the cutting method of the present invention, the length of the product can be measured without stopping the transfer line of the product bar and the production efficiency due to the stop of the transfer line can be prevented. Further, the cutting method of the present invention comprises:
The surplus length of the product bar can be grasped in real time,
A stable extra length can be added to the product steel bar, and the yield can be improved.

[Brief description of the drawings]

FIG. 1 is an overall schematic layout view of a steel bar product cutting facility of the present invention.

FIG. 2 is a block diagram of a method for cutting a steel bar product of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel bar rolling machine 2, 4, 6 Roller table 3 Cooling floor 5 Shearing machine 7 Transfer stand 8a, 8b ITV camera 9 Steel bar product 10 Temperature detector 21 Measurement control device 22 Shear control part 23 Shear machine control device

Claims (1)

[Claims] 1. A method for cutting a steel bar product in which a rolled steel bar is cut to a reference product length by a shearing machine and a surplus length of the cut steel bar product is controlled to a preset length. The cutting length is tracked together with the cut bar product, and when the bar product reaches the transfer table, which is downstream equipment of the shearing machine, the temperature and length are measured, and the extra length at room temperature is determined based on the measurement result. And calculating a difference from the set surplus length to correct the set cut length.