JPH0449043B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for controlling the dimensions of hot circular cross-section rods and wires (hereinafter referred to as rods and wires).

(Prior art) Generally, the diameter tolerance of hot rolled rods and wires is as follows:
According to JIS, the tolerance is within ±1.5% of the diameter, but in recent years, due to advances in technology and the need for customers to omit the drawing process, strict tolerances of ±0.5% have emerged.

As a conventional method of controlling the shape of rods and wires,
So-called tension control, which controls the tension between rolling mills to zero or a small value, is known (Japanese Unexamined Patent Application Publication No. 1983-1999).
Publication No. 163014).

On the other hand, by measuring the dimensions and shape of rolled rods and wires more accurately and quickly, this information can be communicated to operators engaged in rolling work, and the rolling mill can be operated appropriately to meet strict tolerances. On-line measurement techniques are known for
129706).

The idea behind changing the size and shape of rods and wires using tension is that the rolling load of rods and wires is smaller than that of thick plates, hot-rolled steel plates, sections, etc. Since the dimensional variation in the corresponding part (which usually indicates the diameter of the rod and wire rod in the direction perpendicular to the axis of rotation of the roll) is relatively small, the tension between the front and rear rolling mills can be set to zero or a small constant value. By doing this, the free surface diameter (the diameter of the rod or wire in the part that is not in contact with the roll hole, usually in a direction parallel to the roll rotation axis) is kept constant, and the overall shape is therefore uniform. The idea was to make it into something.

(Problem to be Solved by the Invention) Making the tension constant between rolling mills has the effect of making the variation in free surface diameter constant over the entire length of the material, and does not necessarily reduce the variation with respect to the target diameter. do not have.

In addition, the shape (profile) of the rod and wire rod is a complex shape that cannot be approximated by a circle or an ellipse due to the influence of roll wear, so tension control is performed by simply measuring the top and bottom diameters and free surface diameters. It is not possible to guarantee that the entire circumference of the rod or wire rod will be within strict tolerances simply by performing the following steps.

In particular, the dimensional accuracy demanded by customers in recent years has become so strict that even dimensional variations in the vertical direction are a problem, and drastic dimensional control measures have become necessary even in the field of rods and wires.

Therefore, in order to keep the rolling stock within tighter dimensional tolerances, in addition to tension control between rolling mills, it is necessary to control the rolling reduction based on accurate shape measurement data, which is also not necessarily constant for each rolling mill. This must be achieved under conditions where rolled material (billet) must be used.

The present invention provides a method for controlling the dimensions of rods and wires that minimizes the deviation of the entire circumference of the product diameter from the target diameter.

(Means for Solving the Problems) The present invention uses a dimension measuring device that is located downstream of a finish rolling mill and continuously rotates around a bar and wire rod, which is a material to be rolled by finish rolling. Continuously measures the diameter in all _directions of In addition to _calculating D _{x and the minimum diameter Do , the} maximum diameter _D The objective is to control the dimensions of the rod and wire rod so that -D _o )/2 becomes the target diameter, and also to determine the free surface diameter corresponding to the non-contact part of the roll hole type based on the measured value by the above calculation process.
The roll reduction of the rolling mill one upstream from the finishing mill or the tension between the rolling mills is controlled so that D _f becomes a constant value D ₀ between the target diameter or minimum diameter D _o and the maximum diameter D _x . Furthermore, it is a method for controlling the dimensions of rods and wires by combining these methods.

In the rolling of rods and wire rods, there are various dimensional fluctuation factors such as wear of the rolls, the steel type of the material to be rolled, and temperature. The present invention is a dimensional control method that attempts to minimize the deviation of the diameter of the actually rolled product from the target diameter even in the presence of these fluctuation factors.

Fig. 1 shows an embodiment of the present invention, Fig. 2 shows another embodiment of the invention, Fig. 3 shows the relationship between tension between rolling mills and dimensional change, and Fig. 4 shows a further embodiment of the invention. An example is shown below.

Here, we will explain the relationship between roll wear, which is a major dimensional variation factor during rod and wire rod rolling, and the accompanying roll reduction.

For convenience, FIGS. 5a and 5b only show a cross section of the upper left half of the upper roll during material biting.
In the figure, T indicates the top and bottom portions, F indicates the free surface, and X indicates the roll reduction control amount.

Trajectory A in the figure is the profile of the roll at the initial stage of rolling immediately after the installation of a new roll, and trajectory B is the profile of the roll immediately before the roll replacement after rolling the required amount, that is, at the time of completion of rolling. In the roll hole type for rolling rods and wire rods with a circular cross section, wear is greatest at a portion called a shoulder near the free surface F direction due to the shape of the material on the entry side (in this example, an elliptical shape) that serves as the leader. In this case, if the maximum amount of wear is l, the trajectory A has been adjusted so that the top and bottom diameters almost match the target diameter, so the product diameter after roll wear will be in the range of +l from the target diameter, and The deviations are all biased in the positive direction and therefore have large values.

Therefore, by operating the reduction device and reducing the roll by the amount of roll reduction control X, the deviation is divided into positive and negative by making the hole shape the profile shown by the trajectory C as shown in Fig. 5b, and the deviation from the target diameter is reduced. Implement control such as setting the value. Due to such reduction adjustment, the maximum diameter D _x of a general wire rod is often at the shoulder near the free surface F, and the minimum diameter D _o is often at the top and bottom. However, the values of the maximum diameter D _x and minimum diameter D _o change due to other factors such as changes in the steel type and temperature of the material to be rolled, so the roll reduction is adjusted each time to adjust the maximum diameter D _x to the target diameter. , the deviation of the minimum diameter D _o must be minimized.

Also, in the trajectory C in Fig. 5, the free surface diameter D _f is shown to be between the minimum diameter D _o and the maximum diameter D _x , but this represents an ideal state, and in some cases It may eventually become larger than the maximum diameter D _x or smaller than the minimum diameter D _o .
As long as the free surface diameter D _f falls between the minimum diameter D _o and the maximum diameter _D Adjusted to diameter.

The dimensions _{of the} maximum diameter _D It is important that this is possible by adjusting the shape of the material (adjusting the rolling reduction of the roll one upstream from the finishing roll).

Figure 6 shows an example where the finished dimension of the product is 100mm.
In order to see the changes when changing the size and shape of the input material, a φ steel bar is rolled with no tension between the rolling mills, and the dimensions and shape (profile) are shown when the input material size is changed. It is something. That is,
The measurement data recorded by a known rotary dimension measuring device is plotted and displayed with the main parts enlarged.

Trajectory B' in Figure 6 is when the material at the entrance of the upstream rolling mill has a small cross section.
Trajectory A′ is before being made smaller. By reducing the cross section of the entry material, the free surface diameter has been reduced.
It can be seen that the size has decreased from Df ₁ (99.9mm) to Df ₂ (99.5mm).

As described above, in order to realize the present invention, the free surface diameter D _f is first detected, and then the maximum diameter D _x and minimum diameter D _o excluding the free surface diameter are determined, and their positions are determined on the free surface. It is necessary to detect the angles θ _x and θ _o formed with the diameter D _f . However, since twisting occurs in the rod and wire rod, and the amount of twisting is not constant, the angular position of the free surface diameter D _f itself at the position of the dimension measuring device located far from the rolling mill will vary each time. Since it is not possible to determine the absolute position, it is necessary to perform calculations based on the measured values obtained by the dimension measuring device.

The calculation method will be explained below.

FIG. 7 shows the measurement principle of the dimension measuring device previously presented in the prior art section, and shows a rotary dimension measuring device used when carrying out the method of the present invention. 1 indicates a rod and wire rod which is an object to be measured.

The light emitted from the light source 2 passes through the lens 3 and becomes a parallel beam, and the shadow of the wire rod 1 passes through the light receiving lens 4 and forms an image on the photoelectric conversion array element 5.
The photoelectric conversion array element 5 is an application of a charge coupled device (CCD) or a bucket brigade device (BBD), and is integrated with the light source 2 and continuously rotates around the wire rod 1.
The diameter at any position can be measured moment by moment.

The diameter image of the wire rod 1 projected onto the photoelectric conversion array element 5 is outputted from the array element 5 in the form of a pulse train corresponding to brightness and darkness by a shift pulse applied from the transmitter 6, and is counted by the counter 7. Ru. This counting operation is repeated at a predetermined period to perform averaging.

The measurement signal of the diameter value converted into the pulse count value is transmitted to the arithmetic processing unit 9. 8 is a slip ring, 13 is an angle detector, and 14 is a display device.

The angle detector 13 generates a signal each time the measurement position by the above-mentioned measuring device, that is, the axis of the light beam from the light source 2, which is the dimension measuring section, rotates by a predetermined angle θ ₀ . In the case of such a projection-type dimension measuring device, it is possible to measure the diameter of the same part every time it rotates half a turn, or 180 degrees, around the rod and wire material to be rolled, so θ ₀ is
Divide 180° into n equal parts, and use this as the measurement timing angle. When the angle detector 13 detects that the measuring section has rotated by θ ₀ from a certain reference point, the arithmetic processing unit 9 reads a count value from the counter 7 . The 180° rotation of the measurement unit, that is, n pieces, are stored in the input order along with the angle number at the measurement timing angle θ ₀ at that time.

When the number of input diameter values reaches n in this way, the free surface diameter D _f , the maximum diameter D _x excluding the free surface diameter, and the minimum diameter D _o are calculated based on these data.

An example of a signal processing method is shown in FIGS. 8a and 8b. The step-like curve in Figure 8 indicates the finished diameter of the product.
The output data of a rotary dimension measuring device obtained when rolling a steel bar with a diameter of 100 mm was recorded using a pen recorder.

Figure 8a shows the case where tension is applied between the rolling mills or the size of the material entering the rolling rolls is small, and figure b shows the opposite case. The pen recorder sends the chart to the right, and outputs the diameter value input from the device in the vertical direction. Therefore, this is the same as plotting n pieces of diameter value data input by the signal processing device from left to right in the order of input.
The angle indicated without a bracket represents the rotation angle θ of the device, which corresponds to the diameter of the entire circumference at a rotation of 180°. In this example, the change in diameter value is expressed as y=a
It is approximated by curve regression of sinθ.

The angle indicated with a bracket in FIG. 8 is θ of curve regression. The above curve regression was performed n times by shifting the measurement timing angle by θ° according to the rotation angle of the device, and the θ of the case with the largest correlation function was
The diameter at =90° is the free surface diameter D _f .

In the case of FIG. 8a, the actual diameter value is smaller than the value of a sin90°. or,
In the case of b, the actual diameter value is larger than the value of a sin90°. Let a sin90° be the free surface diameter D _f , the maximum diameter outside the range of curve regression angle θ = 60 to 120° be D _x , and the minimum diameter D _o , and save them together with their corresponding angles.

When the above processing is completed, n diameter values and angle number values are initialized, and the next 180° rotation cycle begins.

In this way, various more accurate measured values (calculated values) of the rolled material required for subsequent dimensional control can be obtained, and based on these, the rolling reduction of the rolling mill or the rear tension applied to the rolling mill can be directly controlled. Control is a feature of the present invention.

FIG. 1 is a block diagram of the first aspect of the present invention. The rod and wire rod 1 are rolling rolls 15 and 15' of the i-1 rolling mill.
Then, it is rolled by the rolling rolls 16 and 16' of the i rolling mill, moving toward the right in the figure. Reference numeral 17 denotes a dimension measuring device, which is located downstream of the rolling mill and rotates around the passing wire rod on the pass line of the rolled material, so that the diameter of the entire circumference can be continuously measured.

21 is a reduction control device, which targets a value of Do ₊ (D _x −D _o )/2 based on the values of free surface diameter D _f , maximum diameter D _x , and minimum diameter D _o inputted from the dimension measuring device 17. close to the diameter and so that the free surface diameter D _f becomes the target diameter.
Roll reduction control amount X of the i rolling mill, which is a finishing rolling mill
and the roll reduction amount Y of the i-1 rolling mill located one place upstream of the finishing mill, and are controlled at the same time.

The roll reduction control amounts X and Y are determined as follows.

Roll reduction control amount of i rolling mill In the example of 22 mmφ, the relationship between the amount of change ΔB in the surface diameter D _f is expressed by the following equations (1) and (2) (experimental equation).

ΔA=0・Y+0.91・X ……(1) ΔB=1.19Y−0.83・ ……(2) The amount of dimensional change in the diameter of the part that is in contact with the roll other than the top diameter is the diameter position of the relevant part Letting θ be the angle between the free surface diameter and the free surface diameter, it is determined by ΔH・sinθ. The vertical diameter corresponds to the case where θ=90°.

It is clear from equations (1) and (2) that among the dimensions of the final product, the dimensions of the part that is in contact with the rolls of the finishing mill, including the top and bottom diameters, are the same as those of the finishing mill, i. The change amount ΔB of the free surface diameter D _f that is not in contact with the finishing roll can be controlled only by the amount This requires control using the roll reduction control amount Y of the i-1 rolling mill.

This means that when controlling the dimensions of rods and wire rods, the free surface diameter D _f of the final product and the free surface diameter D _f
Maximum diameter of the part in contact with the finishing roll, excluding
The angle θ _x from the free surface of each of D _x and the minimum diameter D _o ,
This shows that it is necessary to calculate θ _o separately.

Next, a specific control method will be explained.

The amount of change ΔH in the top and bottom diameter due to the rolling control of the i rolling mill
When the control corresponding to is performed, the minimum diameter D _o + ΔH・sinθ _o and the maximum diameter D _x + ΔH・
Since it is most preferable for dimensional accuracy to match the median value of sinθ _x with the target diameter, the amount of change in the top and bottom diameters ΔH
is calculated using equations (3) and (4) below.

(D _x + ΔH・sinθ _x )−= −(D _o +ΔH・sinθ _o ) ……(3) ΔH=(2・−D _x =D _o )/(sinθ _x + sinθ _o ) ……(4) Also, If the free surface diameter D _f is to match the target diameter, the amount of change ΔB in the free surface diameter D _f can be found by equation (5).

ΔB=−D _f ...(5) Substitute the amount of change in the vertical diameter ΔH and the amount of change in the free surface diameter ΔB found in equations (4) and (5) into equations (1) and (2). By solving the simultaneous equations, the respective rolling reduction control amounts X and Y of the i rolling mill and the i-1 rolling mill can be found.

By the way, in general, the minimum diameter D _o is often the vertical diameter (θ _o = 90), so in such cases,
Equation (4) is expressed by equation (6) below.

ΔH=(2D−D _x −D _o )/(1+sinθ _x )……(6) The coefficients of the experimental formulas (1) and (2) are as follows:
Since it varies depending on the characteristics of the rolling mill and the roll conditions such as the hole shape, it should be experimentally determined in advance according to the rolling mill used.

In this case, it is desirable to control the tension between all rolling mills to zero or a very small value, and at the same time control the roll rotation speed to account for the change in mass flow caused by the roll reduction of the i-rolling mill and the i-1 rolling mill. is desirable.

In other words, the dimension control in the present invention involves controlling the free surface diameter D _f by rolling down control of the i-1 rolling mill, and controlling the maximum diameter D _x and the minimum diameter D _o by rolling down control of the i rolling mill. This is a control method. In the figure, the reference numeral 22 indicates the celsin of the i-rolling mill, and the reference numeral 23 indicates the rolling motor. Similarly, 24 indicates the cell machine of the i-1 rolling mill, and 25 indicates the rolling motor.

FIG. 9 is a flowchart of the first invention.

Next, a second aspect of the present invention will be explained using FIGS. 2 and 3.

A second aspect of the present invention relates to a dimension control method for controlling the free surface diameter D _f to a constant value between the maximum diameter D _x and the minimum diameter _Do by using the rear tension of the i-rolling mill.
Here, it is assumed that minimizing the deviation of the maximum diameter D _x and minimum diameter Do from the target _diameter is left to the operator's roll reduction operation in response to changes in roll wear, dimensional standards, etc. The same symbols as in FIG. 1 indicate the same parts. In the figure, 18 indicates a tension measuring device, and 19 indicates a tension controlling device.

FIG. 3 shows experimental data representing the relationship between tension and change in free surface diameter, ie, change in width ΔB/B of the rod and wire rod. If B ₀ is the free surface diameter in infinite force rolling and B is the free surface diameter in tension rolling, then the difference B ₀ - B = ΔB is the amount of change in free surface diameter due to tension rolling, and it can be expressed as the free surface diameter It is expressed as the ratio of change in width, that is, the width change ΔB/B. σ
represents tension, and the tension on the downstream side of the rolling stand was classified as forward tension, and the tension on the upstream side was classified as rear tension. k indicates the deformation resistance which varies depending on the steel type of the material to be rolled, temperature, etc.

As for the tension applied to the rolling mill i, which is the rolling mill concerned, as it is clear from Fig. 3, the width change due to the rear tension is larger than the width change due to the front tension, and also when the i rolling mill is the final stand. Control using rear tension is particularly appropriate.

When the present invention is implemented using rear tension, the target tension is determined by the following equation (7).

=(k/K)×((D _f −D ₀ )/D _f ) ……(7) In equation (7), k is the change resistance, K is the tension-width change conversion coefficient, and as shown in Fig. 3, In this case, K=0.44, but the value differs depending on the hole type. D ₀ is a constant value of the diameter to be obtained by controlling the tension, and may be any constant value between the minimum diameter D _o and the maximum diameter D _x depending on the purpose.

The reason why D ₀ is not set as the target diameter is that if the target diameter is not between the minimum diameter D _o and the maximum diameter D _x , the deviation in diameter (difference between the maximum diameter and the minimum diameter) will become unnecessarily large.

The calculated target tension is input to the tension control device 19 shown in FIG. 2, and the tension of the i-1 rolling mill is controlled to the target tension by controlling the roll rotation speed of the rolling mill. 20 is a roll drive motor of the i-1 rolling mill. The tension control device 19 controls the roll drive mole 20 of the i-1 rolling mill corresponding to the target tension.
The rotational speed correction value is calculated and outputted, and at the same time it is controlled to apply an appropriate rear tension to the i rolling mill.

FIG. 10 is a flowchart of the second invention.

Next, the third aspect of the present invention will be explained using FIG. 4.

The third aspect of the present invention is to control _the maximum _{diameter D} This is the dimension control dimension to be carried out.

FIG. 4 is a configuration diagram of the third aspect of the present invention. The same reference numerals as in FIGS. 1 and 2 indicate the same parts.

The reduction control device 21 calculates D _{o +} ( _{D x}
−D _o )/2 is the target diameter, maximum diameter D _x , minimum diameter
In order to realize D _o , the roll reduction control amount X of the i rolling mill is calculated and controlled at the same time. The value of the roll reduction control amount X can be determined by the above equation (1) and equations (3) and (4).

The roll reduction is controlled by controlling the reduction motor 23 based on the input of the current value of the reduction of the Celsin 22.

The third aspect of the present invention differs from the second aspect in that a target tension for making the free surface have the target diameter is determined.
That is, D ₀ is used in equation (7) instead of D 0 . Although the tension control device 19 is included to perform control similar to the second invention, it is also necessary to simultaneously control the roll rotation speed for the change in mass flow caused by roll reduction of the i-rolling mill. Therefore, the value of the roll reduction control amount X is input from the roll reduction control device 21.

FIG. 11 is a flowchart of the third invention.

The second and third aspects of the present invention have been described above, and in each case, the free surface diameter D _f was controlled by the tension applied to the i-rolling mill. Even if a constant amount of this tension is applied over the entire length of the material to be rolled, when the i-1 rolling mill is released, the free surface diameter D _f on the exit side of the i-rolling mill will fluctuate.

However, since the tension applied to control the free surface diameter D _f is not a very large value, this variation is often a relatively small value.
If the dimensional standards are even stricter, this may become a problem, so it is desirable to apply the first invention.

(Effects of the Invention) The present invention provides a dimensional control method for rods and wire rods that minimizes the deviation of the entire circumference of the finished product diameter from the target diameter, despite factors such as dimensional changes such as roll wear, steel type of the rolled material, and temperature. Therefore, it is extremely useful for precision rolling.

[Brief explanation of the drawing]

Figures 1, 2, and 4 are explanatory diagrams of an embodiment showing the configuration of the present invention, Figure 3 is an explanatory diagram showing the relationship between tension and free surface diameter change, and Figure 5 is an illustration of roll wear and its effects. An explanatory diagram showing the control of rolling reduction of the accompanying rolls,
Figure 6 is a chart showing the measurement data of the rotary shape measuring device when a 100mmφ steel bar is rolled between rolling mills in a tension-free state, and Figure 7 is the rotary shape dimensions used when carrying out the present invention. FIG. 8 is an explanatory diagram showing a specific example of a signal processing method, and FIGS. 9, 10, and 11 are flowcharts of the present invention. DESCRIPTION OF SYMBOLS 1... Rod wire material, 2... Lamp, 3, 4... Lens, 5... Photoelectric conversion array element, 6... Oscillator,
7...Counter, 8...Slip ring, 9...
Arithmetic processing unit, 13... Angle detector, 14... Display device, 15, 15', 16, 16'... Roll roll, 17... Diameter measuring device, 18... Tension setting device, 19... Tension control Device, 20... Roll drive motor, 21... Rolling down control device, 22, 24...
Sershin, 23, 25...pressure motor.

Claims (1)

[Claims] 1. The size and shape of the bar and wire rod after finish rolling are continuously measured by a rotary dimension measuring device installed downstream of the i-rolling mill, which is a finish rolling mill, and the free surface diameter of the bar and wire rod is determined. D _f and the maximum diameter D _x excluding the free surface, minimum diameter D _o and the angle θ of the maximum diameter D _x from the free surface diameter D _{f x and} the minimum diameter D _o
The angle θ _o of is determined by calculation processing, and due to the roll reduction of the i rolling mill, the amount of change in the top and bottom diameter ΔH = (2・Target diameter − D _x − D _o )/(sinθ _x + sinθ _o ) A method for controlling the dimensions of a rod or wire rod, characterized in that the amount of change in free surface diameter is controlled to be ΔB=−D _f by roll rolling of an i-1 rolling mill located one upstream. 2 Continuously measure the dimensions and shape of the bar and wire rod after finish rolling using a rotary dimension measuring device installed downstream of the i-rolling mill, which is a finish rolling mill, and calculate the free surface diameter D _f and free surface of the bar and wire rod. _{The maximum diameter D _} 1. A method for controlling dimensions of rods and wires, characterized in that a target tension is determined through calculation processing, and the number of rotations of rolls in an upstream rolling mill I-1 is controlled based on that value. 3 The dimensions and shape of the rod and wire rod after finish rolling are continuously measured using a rotary dimension measuring device installed downstream of the i rolling mill, which is a finishing mill, and the free surface diameter D _f and free surface of the rod and wire rod are calculated. The angle θ _{x of the maximum diameter D x} from the maximum diameter D _x , the minimum diameter D _o and the free surface diameter D _{f x} and the minimum diameter D _o
The angle θ _o of is determined by calculation processing, and the amount of change in vertical shape ΔH = (2・Target diameter - D _x - D _o ) / (sin θ _x + sin θ _o ) due to the roll reduction of the i rolling mill. While controlling, the amount of change in free surface diameter ΔB=
The target tension to be applied to the i-rolling mill so as to obtain D-D _f is determined by calculation processing, and the roll rotation speed of the i-1 rolling mill located upstream is controlled based on that value. A method for controlling the dimensions of rods and wires.