JPH0550116A - Method for setting roll gap of caliber roll mill - Google Patents

Abstract

PURPOSE:To provide a target roll gap from the start of rolling by assembling the roll housing of a caliber roll into a stand and sucking the loosenesses of roll shafts, chocks, bearings, etc., in the setting of a roll gap before rolling. CONSTITUTION:In a method by which the roll housing of the caliber roll mill is assembled into a rolling stand to set a roll gap, as the flange parts of the caliber rolls 2,3 of the roll housing assembled into the rolling stand come in contact with each other, the roll gap is tightened as far as a prescribed load is obtained and a correction value of an amount of mill rigidity for a prescribed load is considered as a reference point of the roll gap, the roll gap before rolling is set. The loosenesses of roll shafts, chocks, bearings, etc., in the roll housing are sucked, the roll gap before rolling can be set so that the roll gap in rolling forms the target roll gap and the yield of the product is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting a roll gap of a hole type roll mill to a target roll gap by absorbing looseness in a roll housing.

[0002]

2. Description of the Related Art In a rolling mill using a hole type roll such as a mandrel mill, which is one of the seamless steel pipe manufacturing methods,
The hole type is composed of a pair of rolls having an intersecting angle of 90 ° with an adjacent stand. For example, in a mandrel mill, since rolling is performed by continuous stands, the rolling load applied to each stand greatly changes depending on the rolling schedule, material deformation resistance, roll and bar friction coefficient, and roll diameter. To measure the rolling load, a load cell is generally inserted between the rolling screw of the rolling mill and the bearing box.

To determine the roll gap in the mandrel mill, as shown in FIG. 3, the distance 23 between the flange portions of the roll 21 and the roll 22 when the roll reaction force is present is set as the target amount of the roll gap. Therefore, as shown in the following equation, before rolling, the roll housing is preliminarily closed from the target roll gap amount based on the mill rigidity of the roll housing and the load prediction of the rolled material. GAPa = GAPb−K · P However, GAPa: roll gap amount before rolling GAPb: target gap amount during rolling K: mill rigidity P: load prediction of rolled material At this time, in determining the roll gap amount before rolling, In the conventional method, the roll gap before pre-rolling (GAPa) is set with the state where the roll housing is incorporated in the rolling stand and the flanges of the rolls 21 and 22 are in contact with each other as a reference point.
Had been set.

However, in the roll housing, looseness occurs in the roll shaft and the bearing, the bearing and the chock, the chock and the housing receiving surface, etc., and even if the proper mill rigidity and the load of the rolled material are predicted, the target is reached at the start of rolling. Each time the roll housing was replaced, there was a situation in which the roll gap did not occur and the prescribed thickness reduction could not be performed. Further, as a rolling load control device in a rolling mill, in which the roll gap of a rolling roll is controlled by each different position control system, a position control system that controls one end of the rolling roll according to the rolling load, and the rolling roll. There has been proposed a device (Japanese Patent Application Laid-Open No. 58-65509) equipped with a position control system for controlling the positions of both ends of the device while maintaining the balance of the relative position difference.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The device disclosed in Japanese Patent No. 509 obtains a position correction signal from a deviation between a rolling load detected by a rolling load detector and a target rolling load, inputs the position correction signal to a roll position controller, adjusts the roll position, and then rolls the rolling load. To control. Furthermore, the position error correction signal obtained by comparing the position error detected by the position detector with the set position reference is sent to the position controller so that the balance of the position difference between the working side and the driving side of the lower roll is not disturbed. By inputting, the position of the lower roll on the drive side is adjusted, and at the same time, the balance of the position difference between the working side and the drive side is maintained. However, nothing is mentioned about the setting of the position reference, that is, the setting method of the roll gap.

An object of the present invention is to incorporate a roll housing into a stand, and when setting a roll gap before rolling, the looseness of a roll shaft, a chock, a bearing, etc. is absorbed so that a target roll gap amount during rolling from the start of rolling is It is to provide an obtained roll gap setting method.

[0007]

Means for Solving the Problems As a result of various studies and tests to achieve the above object, the present inventors have found that when a roll housing is incorporated into a stand and a roll gap before rolling is set, an upper roll and a lower roll are set. Contact the flanges of the right and left rolls, tighten the roll gap until a certain predetermined load is generated between the rolls, and adjust the mill rigidity for the predetermined load to the upper and lower roll positions. By setting the roll gap amount before rolling as the contact position, that is, the roll gap reference point, looseness of the roll shaft, chock, bearings, etc. in the roll housing is absorbed, and appropriate mill rigidity and rolling load prediction are used to predict the rolling load. The present invention has been achieved by finding that a target roll gap can be obtained.

That is, according to the present invention, in a method of incorporating a roll housing of a hole roll mill into a rolling stand and setting a roll gap, the flange portion of the hole roll of the roll housing incorporated into the rolling stand is kept constant. The roll gap is tightened until the load is reached, and the value obtained by correcting the mill rigidity amount under a predetermined load is set as the roll gap reference point, and the roll gap before rolling is set.

[0009]

In the present invention, the roll gap is tightened until a predetermined load is achieved with the flange of the hole type roll of the roll housing assembled in the rolling stand in contact with each other.
Since the value obtained by correcting the mill rigidity amount of the predetermined load is used as the reference point of the roll gap, looseness of the roll shaft, the chock, the bearing, etc. in the roll housing is absorbed by the correction of the mill rigidity amount of the predetermined load. As a result, if the roll gap before rolling start is set by appropriate mill rigidity and rolling load prediction, the target roll gap can be obtained from the start of rolling, there is no variation in rolling conditions between roll housings, and good wall thickness reduction is achieved. Is possible.

Therefore, in the conventional method, the roll gap does not reach the target gap amount due to the looseness of the roll shaft, the chock, the bearing, etc. in the roll housing immediately after the start of rolling after changing the rolls, making it difficult to perform a predetermined thickness rolling. However, in the method of the present invention, a predetermined target gap amount is immediately obtained immediately after the start of rolling after the roll change, and it is possible to obtain a rolled product with a predetermined thickness rolling, and the product yield is improved accordingly. To do.

[0011]

【Example】

Embodiment 1 Details of the present invention will be described below with reference to FIGS. 1 and 2 showing an example of an embodiment. FIG. 1 shows an example of a control system diagram of the present invention. Reference numeral 1 is a tube in a mandrel mill.
Are the rolls 4, 5, and 5 are the drive sides of the rolls 2, 3. Reference numeral 6 is a screw for rolling down the hole-type roll 2, and 7 is a load cell for rolling load measurement inserted between the screw 6 for rolling down and the bearing box. 8 is an electric motor for driving the reduction screw 6, 9 is a roll position detector, 10 is a roll position controller, 11 is a roll gap setting device, and 12 is a target rolling load setting device.

Then, the roll position control unit 10 compares and calculates the detection signal of the load cell 6 and the set value of the target rolling load setting device 12 to obtain a deviation signal regarding the rolling load. Further, the roll position control unit 10 compares the detected roll position input from the roll position detector 9 and the target roll gap set by the roll gap setting device 11, and calculates the deviation signal of the obtained roll gap and the rolling. The position of the upper roll 2 is controlled by the drive motor 8 based on the deviation signal regarding the load.

In the rolling load control with the above-mentioned structure, the hole type rolls 2 and 3 of the roll housing incorporated in the rolling stand are provided.
In setting the roll gap before the start of rolling, a drive signal is output from the roll position control unit 10 to the drive electric motor 8 to reduce the hole type roll 2 by the screw 6 for reduction and to change the hole type rolls 2 and 3. Contact the flange part. After that, the load detected by the load cell 7 is reduced by the reduction screw 6 until it becomes a predetermined load, for example, P _0, and the position L ₀ detected by the roll position detector 9 at that time is detected by the roll position control unit 10. The roll position L at the time when a predetermined load is applied from the roll gap is obtained from the mill rigidity curve of the housing characteristics shown in FIG. ₀ is subtracted and set as the roll gap before rolling by the roll gap setting device 11.

Therefore, the roll gap before rolling set by the roll gap setting device 11 is set with the roll position at the time when a predetermined load is applied as a reference point.
Looseness of the roll shaft, chocks, bearings, etc. in the roll housing is absorbed, and by predicting the appropriate mill rigidity and rolling load, it is possible to obtain the target roll gap during rolling, and the variation of rolling conditions among roll housings. This makes it possible to set a good roll gap, it is possible to carry out predetermined rolling from the start of rolling, and it is possible to improve the product yield.

Example 2 In a mandrel mill consisting of 7 stands, an outer diameter of 18
When rolling a 1 mm thick wall tube with a wall thickness of 17.0 mm into a shell with an outer diameter of 151 mm and a wall thickness of 6.0 mm, the roll housings of each stand are rearranged to set the roll gap before rolling. After bringing the flange portion of the roll into contact, the method of the present invention in which the roll gap before rolling was set with the roll gap at the time of applying a predetermined load as a reference point, and the flange portion of the hole type roll was brought into contact with each stand. For each of the conventional methods in which the roll gap before rolling was set with the roll gap at that point as a reference point, the other was rolled under the same rolling conditions, and the shell was used as the shell. As a result, in the method of the present invention, looseness of the roll shaft, chock, bearings, etc. in the roll housing was absorbed, and the roll gap during rolling from the start of rolling became the target roll gap, but in the conventional method, Due to the looseness of the roll shaft, chocks, bearings, etc., a rolling situation occurred where the roll gap at the start of rolling did not reach the target roll gap.

[0016]

As described above, according to the method of the present invention, when the roll gap is set before rolling when the roll housing is reassembled, looseness of the roll shaft, chocks, bearings, etc. in the roll housing is absorbed during rolling. The roll gap before rolling can be set so that the roll gap of No. 1 becomes the target roll gap, and the product yield can be improved.

[Brief description of drawings]

FIG. 1 is an example of a roll gap control system diagram of the present invention.

FIG. 2 is a mill stiffness curve for a housing.

FIG. 3 is an explanatory diagram of a conventional roll gap setting method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Elementary pipe 2, 3 Hole type roll 4, 5 Driving side 6 Screw for reduction 7 Load cell 8 Electric motor for driving 9 Roll position detector 10 Roll position control unit 11 Roll gap setting device 12 Target rolling load setting device 21, 22 Roll 23 Distance between flanges

Claims (1)

[Claims] 1. A method of setting a roll gap by incorporating a roll housing of a hole type roll mill into a rolling stand, wherein a predetermined load is applied in a state where a flange portion of a hole type roll of a roll housing incorporated in the rolling stand is in contact. A roll gap setting method for a hole-type roll mill, comprising: setting a roll gap before rolling by using a value obtained by tightening the roll gap up to, and correcting a mill rigidity amount of a predetermined load as a roll gap reference point.