JPH0549101U - Speed controller for stretch reducer mill - Google Patents

Abstract

(57) [Summary] [Purpose] To make it possible to perform rolling with a stretch reducer mill even on pipes with welded parts. [Structure] When the welding point W of the rolled pipe 1 passes through the rolling stand A ₁ , the welding point detecting means S ₁ detects the passage. The correction timing calculation means 5 calculates the time from when this detection is performed until the welding point W reaches directly under the rolling roll R ₁ , and this is calculated as the speed reference calculation means 11
Let us know. The speed correction amount output means 10 calculates the speed correction amount of each rolling roll in advance and outputs it to the speed reference calculation means 11. After the welding point W has passed directly under the rolling roll R ₁ and is between the rolling stands A _{1 and} A ₂ , the speed reference calculation means 11 increases the rotation speed of the rolling roll R ₁ to rotate the rolling roll R ₂ . Same as speed. Therefore, no tensile force is applied to the welding point W moving between the rolling stands A _{1 and} A ₂ .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a speed control device for a stretch reducer mill for rolling a pipe.

[0002]

[Prior Art]

 The stretch reducer mill is composed of multiple rolling stands.By giving a speed difference between the rolling rolls of each rolling stand, a tensile force is generated in the longitudinal direction of the pipe to be rolled. Is a device for obtaining.

[0003]

[Problems to be solved by the device]

 As described above, the tensile force is always applied in the longitudinal direction of the rolled pipe during rolling, so the target of the rolled pipe is a seamless pipe such as a seamless pipe by welding. It was limited.

That is, when a plurality of pipes are spliced together by welding to form a single pipe and applied to a Stretch reducer mill, tensile force is applied to the welded portion of the pipe, so that the welded portion is broken or the pipe is broken. Problems such as deterioration of the shape will occur. Therefore, conventionally, the pipe having the welded portion has not been rolled by the Stretch reducer mill.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a speed control device for a stretch reducer mill that enables rolling by a stretch reducer mill even for a pipe having a welded portion. Has a purpose.

[0006]

[Problems to be solved by the device]

 As a means for solving the above problems, the present invention is a stretch reducer mill that forms a pipe to be rolled into a predetermined shape by passing the pipe to be rolled through a plurality of rolling stands. When a welding point detecting means is provided which detects passage of a welding point of the pipe to be rolled, and when the welding point passes through two pairs of rolling stands adjacent to each other, only one of these two pairs of rolling stands is used. For at least one of the rolling rolls, the speed correction amount output means for outputting a pre-calculated speed correction amount for preventing the tension from being applied to this welding point, and the welding point detection means described above are used for the welding point. After detecting the passage of the welding point, a correction timing calculating means for determining the time when the welding point reaches directly below the rolling stand associated with each welding point detecting means. From the time point obtained by the correction timing calculation means, the speed reference calculation means for correcting the speed reference command value for the rolling roll by the speed correction amount from the speed correction amount output means, and the speed reference calculation means Rolling roll speed control means for controlling the speed of the rolling rolls based on a command value.

[0007]

[Action]

 In the above structure, when the welding point of the pipe to be rolled approaches the first rolling stand and passes the first welding point detecting means, the correction timing calculating means causes the welding point to detect the first rolling point from the detection signal. The time when the vehicle arrives directly under the stand is calculated, and the calculation result is notified to the speed reference calculation means.

When the notified time comes, the speed reference calculation means determines the speed correction amount output from the speed correction amount output means with respect to at least one of the first or second rolling stands of the rolling rolls. , Correct the speed reference command value. The rolling stand to be corrected in this case is predetermined.

Then, the rolling roll speed control means related to the predetermined one of the rolling stands controls the speed of the rolling rolls based on the corrected speed reference command value. Therefore, no tensile force acts on the welding point moving between the first and second rolling stands. At this time, a tensile force is applied in the longitudinal direction between each of the second and subsequent rolling stands, as is conventional.

Next, the welding point approaches the second rolling stand, and the second welding point detecting means detects the passage thereof, and thereafter, the same operation as described above is performed. That is, the tensile force is not exerted on the welding point moving between the second and third rolling stands. At this time, a tensile force is applied in the longitudinal direction between the first and second rolling stands and to the third and subsequent rolling stands as in the conventional case.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing the configuration of this embodiment. The pipe 1 to be rolled is a pipe of schedule a and a pipe of schedule b added by welding, and a welded portion W has a build-up portion.

This pipe 1 to be rolled is adapted to be rolled by a plurality of rolling stands A _{1 to} A _n , and welding point detection means S _{1 to} S _n are provided on the upstream side of each rolling stand. ing. Rolling roll R ₁ to R _n rolling stands A ₁ to A _n are driven by a motor M ₁ ~ M _n, these motors M ₁ ~M _n rolling rolls speed control means, such as Leonard device C ₁ -C _n It is controlled. Further, pulse generators PG _{1 to} PG _n for speed detection are attached to the motors M ₁ to M _n (however, only PG ₁ is shown for convenience of the drawing).

The signals from the welding point detection means S _{1 to} S _n are sent to the correction timing calculation means 5 via the conversion circuit 2, the filter circuit 3, and the output circuit 4, and the pulse generation is performed. The signals from the devices PG _{1 to} PG _n are also sent to the correction timing calculation means 5.

In addition to the above signals, the correction timing calculation means 5 calculates a signal for setting the roll diameter in each rolling stand from the roll diameter setting device 6 and a correction start timing from the correction coefficient setting device 7. A signal for setting the correction coefficient K used in the case of inputting is also input.

The speed reference setter 8 outputs a set value signal for the speed reference command of each rolling stand, and the schedule setter 9 sets a value for the speed ratio between the rolling stands which is suitable for the rolling schedule. It outputs a signal. The speed correction amount output means 10 preliminarily calculates the speed correction amount of each rolling roll for preventing the tensile force from being applied to the welding point W of the pipe 1 to be rolled, based on the input of these signals. This is output to the speed reference calculation means 11.

The speed reference calculation means 11 corrects the speed reference command value for each rolling roll by the correction amount given by the speed correction amount output means 10 from the correction start time obtained by the correction timing calculation means 5. It is like this.

FIG. 2 is an explanatory diagram showing a specific configuration of the welding point detecting means S ₁ in FIG. The welding point detecting means S ₁ is composed of an iron core 12, a rod 13 which is magnetically inserted through the iron core 12 so as to be vertically movable, and a coil 14 which is wound near the tip of the rod 13. ..

The conversion circuit 2 is a circuit for converting the displacement of the rod 13 in the coil 14 into an electric signal, and the filter circuit 3 is for removing vibration noise and the like. The output circuit 4 outputs the output of the filter circuit 3 as a detection signal to the correction timing calculation means 5.

Next, the operation of this embodiment configured as described above will be described. In FIG. 1, it is assumed that the welding point W gradually approaches the welding point detecting means S _{1 from} the upstream side, that is, the left side of the welding point detecting means S ₁ and finally reaches the welding point detecting means S ₁ . Then, as shown in FIG. 2, the end of the rod 13 is pushed down by coming into contact with the welding point W, so that the magnetic flux in the coil 14 changes and a current change occurs. This current change is converted into an electric signal by the conversion circuit 2, and is further sent from the output circuit 4 through the filter circuit 3 to the correction timing calculation means 5 as a welding point detection signal.

Upon receipt of this detection signal, the correction timing calculation means 5 calculates the time T ₁ required for the welding point W to reach the position directly below the rolling roll R _{1 according} to the following equation, and this is used as the speed reference calculation means. Make sure to inform 11.

T ₁ = K · L ₁ / D ₁ · V ₁ Here, K is a correction coefficient determined by the pipe shape and the stretch amount, and L ₁ is from the position of the welding point detection means S _{1 to} the position immediately below the rolling roll. distance, D ₁ is the rotational speed of the rolling rolls R ₁ that is detected with a diameter of the rolling roll R _1, the pulse generator PG ₁ (rpm).

Then, the speed reference calculation means 11 controls the rolling roll speed control means C _n based on the speed correction amount relating to the rolling roll R ₁ given from the speed correction amount output means 10 from the time when the time T ₁ has elapsed. Make a correction to increase the speed reference command value.

[0023] That is, when the welds W which has moved from the left side in FIG. 1 has reached the right under position location of the rolling rolls R _1, rolling rolls R ₁ is that Do the same rotation speed as the rolling rolls R ₂ The speed is controlled as follows.

Accordingly, no tensile force is applied to the welding point W while the welding point W moves from the rolling stand A ₁ to the rolling stand A ₂ . At this time, tensile force acts on the pipe 1 to be rolled between the rolling stands A ₂ A _3, between A ₃ A ₄ , ..., A _n-1 A _n as in the conventional case. Fig. 3 is a characteristic diagram showing the roll rotation speed of each rolling stand (the number of stands: 24) at this time, and Fig. 3 (a) shows the state before the welding point W reaches the rolling stand A _1. FIG. 3B shows a state where the welding point W is between the rolling stands A _{1 and} A ₂ .

As is apparent Come to focusing between rolling stands A ₁ A _2, subjected to any tension occurring speed difference between the FIGS. 3 (a) the rolling stand A ₁ and A ₂ However, in Fig. 3 (b), there is no speed difference between the two, and the tensile force is not working.

Next, the welding point W is detected by the welding point detecting means S ₂ , and thereafter, the same operation as described above is performed. That is, when the welding point W reaches the position directly below the rolling roll S ₂ , the rotation speed of the rolling roll R ₂ is increased until it becomes the same as that of the rolling roll R ₃ . Therefore, no tensile force is applied to the welding point W moving between the rolling stands A ₂ A ₃ .

At this time, tensile force acts on the pipe 1 to be rolled between the rolling stands A ₁ A _2, between A ₃ A _{4, and} between A _n-1 A _n , as in the conventional case. After the welding point W has passed between the rolling stands A _{1 and} A ₂ , the rotation speed of the rolling roll R ₁ is reduced by a predetermined value. As a result, the tension between the rolling stands A _{1 and} A ₂ can be made the same value as before the welding point W passed.

As described above, when the welding point W passes between the rolling stands A _{1 to} A _n , the rotation speeds of the rolling rolls before and after the welding point W are equal to each other. You can avoid applying force. Therefore, it is possible to prevent breakage of the welded portion W or deterioration of the pipe shape.

In the description of the above embodiment, when the welding point W is, for example, between the rolling stands A _{1 and} A ₂ , the rotation speed of the upstream rolling roll R ₁ is changed to that of the downstream rolling roll R ₂ . By increasing the speed, the tensile force between the two was eliminated. In order to eliminate the tensile force between the _two , a method of lowering the rotational speed of the downstream side rolling roll R _{2 to} the rotational speed of the upstream side rolling roll R ₁ , or raising and lowering both rolling rolls by a predetermined amount respectively. A method of lowering it is possible. However, decelerating the rolling roll on the downstream side is not preferable from the viewpoint of process control and the like, so control is performed to increase the rotational speed of the upstream rolling roll R ₁ as described in the above embodiment. Is normal.

Further, in the above embodiment, as the welding point detecting means, as shown in FIG. 2, the one using an electromagnetic coil is used, but each rolling stand is provided with a load cell, and the pressure detected by this load cell is used. It is also possible to adopt a configuration in which the passage of the welding point W is detected by the change.

[0031]

[Effect of the device]

 As described above, according to the present invention, when a welded portion of a pipe to be rolled passes through a plurality of rolling stands, speed control of at least one of the rolling stands before and after the welded portion is performed. By doing so, the tensile force is not applied to the welded part, so it is possible to perform rolling processing with a stretch reducer mill even on a pipe having a welded part.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory view showing a specific configuration of a welding point detecting means in FIG.

FIG. 3 is a characteristic diagram for explaining the operation of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Pipe to be rolled 5 Correction timing calculation means 10 Speed correction amount output means 11 Speed reference calculation means A _{1 to An} rolling stand R _{1 to} R _n Rolling rolls C _{1 to} C _n Rolling roll speed control means W Welding point S ₁ to S ₂ Welding point detection means

Claims (1)

[Scope of utility model registration request] 1. A stretch reducer mill for forming a pipe to be rolled into a predetermined shape by passing the pipe to be rolled through a plurality of rolling stands. The stretch reducer mill is provided upstream of each of the rolling stands and welds the pipes to be rolled. And a welding point detecting means for detecting passage of a point, and when the welding point passes through two sets of rolling stands adjacent to each other, at least one rolling roll of these two sets of rolling stands Speed correction amount output means for outputting a pre-calculated speed correction amount for preventing tension from being applied to the welding point, and each welding point detecting means after detecting passage of the welding point, and then each welding point The correction timing calculation means for obtaining the time when this welding point reaches just below the rolling stand related to the detection means, and the correction timing calculation means From the point in time, based on the command value from the speed reference calculation unit that corrects the speed reference command value for the rolling roll by the speed correction amount from the speed correction amount output unit, and the command value from the speed reference calculation unit, the rolling A speed control device for a stretch reducer mill, comprising: a rolling roll speed control means for controlling the speed of rolls.