JPH069694B2 - Mandrel drawing method in mandrel mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a state in which the axial velocity of a mandrel is controlled to a given value when rolling a metal pipe in a state where a mandrel is fitted in its hollow portion. The present invention relates to a method of pulling out a mandrel from a metal tube after rolling in a mandrel mill of a semi-floating mandrel system that is rolled below.

(Prior Art) When rolling a metal tube with a mandrel mill, rolling is performed with the mandrel fitted in the hollow portion of the metal tube.

It is important to quickly remove the mandrel from the metal tube after rolling. If this is not done, the metal tube in the hot state tightens the mandrel by heat shrinkage due to cooling, and becomes a so-called "shrink fit" state, and it is extremely difficult to pull the mandrel from the metal tube, or It will be impossible.

FIG. 4 shows some conventional methods for removing a mandrel from a metal tube.

FIG. 4 (a) shows that after rolling the metal pipe, the extractor 2 installed in the latter stage of the rolling mill train 1, that is, the metal pipe 3.
Is a method of pulling out the mandrel 4 from the metal tube 3 with a plurality of hole-type rolling mills (extractors) that restrict the outer diameter of the. After withdrawing from the metal tube 3, the mandrel 4 is returned to the front stage of the rolling mill train 1 by the device 5 that holds the shaft end of the mandrel 4 and regulates the speed.

FIG. 4 (b) shows that after rolling the metal pipe, the metal pipe 8 is rolled in the rolling mill row 6 while the mandrel 9 is still fitted to the axial part of the hollow portion of the metal pipe. In the middle of, the mandrel 9 is released from the device 10 that holds the mandrel shaft end and regulates the axial speed of the mandrel, and in that state, the metal tube 8 is discharged to the outside of the rolling mill train 6 and further carried out of the line. , While holding the shaft end of the mandrel 9 by the restraint device 11 and restraining the movement of the metal pipe 8 in the axial direction by the stripper 7, displace the restraint device 11 in the direction of extracting the mandrel from the metal pipe. It is a method of pulling out from the mandrel metal pipe.

In the case of the method shown in FIG. 4 (a), although the mandrel is quickly extracted from the metal pipe, the mandrel 4 extracted from the metal pipe passes through the rolling mill train 1 and the rolling mill train 1
Since the cycle of returning to the previous stage is adopted, there is a drawback that the operating rate of the rolling mill train 1 is reduced and the productivity is reduced.

On the other hand, in the case of the method shown in FIG. 4 (b), when transferring the metal tube in which the mandrel is fitted to the mandrel extracting means,
Usually, it takes more than ten seconds, so that the temperature drop of the metal pipe not only makes it difficult to remove the mandrel, but also causes scratches on the inner surface of the metal pipe due to the removal of the mandrel.

Regarding the method of drawing the mandrel from the metal tube, for example, in JP-A-58-74206, the full-floating mandrel mill method, the retained mandrel mill method and the retract mandrel mill method can be carried out in the same line,
Although it discloses the penetration of a mandrel into a blank tube, the rolling of a metal tube and the drawing out of a mandrel, the problems mentioned above have not been fully solved.

(Problems to be Solved by the Invention) In the present invention, a metal tube is rolled under a condition in which the axial speed of the mandrel is controlled to a given value, and during the rolling, the speed control of the mandrel is canceled. Then, the mandrel is released, and the mandrel is rolled into a full-floating mandrel. Without causing
In addition, it is a technical issue to obtain a mandrel drawing method that does not reduce productivity by lowering the operating rate of the rolling mill train as compared with the case where the drawing of the mandrel is not considered.

(Means for Solving the Problem) The gist of the present invention is to install a metal tube and a mandrel in its hollow part by a rolling mill train including a plurality of rolling mills of individual driving type arranged in series. In this state, the mandrel following the tail end of the rolled metal pipe is gripped in the subsequent stage of the rolling device for rolling while controlling the axial speed of the mandrel to a predetermined value, and the axial speed is regulated 1 One or more mandrel speed control devices and one or more metal pipe speed control devices for gripping the rolled metal pipe to control the axial speed thereof are provided in this order, and immediately after the end of rolling, the rolling mill train After releasing the mandrel from the control of its axial velocity, releasing the metal tube with the mandrel still fitted from the rolling mill train, and opening the rolling mill train to the rolling of the subsequent metal pipe, the mandrel is removed. Gold as fitted The metal pipe is controlled by the metal pipe speed control device, and the mandrels projecting to the rolling mill row side while being fitted to the metal pipe are respectively held by the mandrel speed control device, and the axial speed of the metal pipe is controlled by the mandrel shaft. There is a mandrel drawing method in a mandrel mill, which is characterized in that the mandrel is drawn from the metal pipe at a speed higher than the directional speed.

The present invention will be described in detail below.

This invention rolls a metal tube under a condition in which the axial speed of a mandrel mill is controlled to a given value, releases the mandrel in the middle of rolling, and shifts to a full-floating mandrel state for rolling. When rolling a metal tube with a mill, if pulling out the mandrel from the metal tube is started immediately after rolling, the pulling force will be much smaller and it will be easier to pull out experimentally and empirically. It is based on what you have done.

For that purpose, it is essential to install a mandrel drawing device in the rolling line, and therefore it was devised to use a compact roller as a means for drawing the mandrel from the metal tube.

That is, immediately after rolling is completed, the metal tube and the mandrel are restrained at the same time by rollers, and a relative speed difference is provided between the roller contacting the metal tube and the roller contacting the mandrel, so that the friction force is immediately applied after rolling. , Decided to pull out the mandrel from the metal tube.

(Embodiment) Based on the preferred embodiment of the present invention shown in FIG.
The present invention will be described in more detail. In FIG. 1, 12 is a rolling mill train, and 13 is a device for holding the mandrel shaft end to regulate the speed. A is a roll group, the outer diameter of the metal pipe,
This is a metal pipe speed regulating device consisting of a pair of rolls 14 which is movably restrained in the axial direction. Each roll pair constituting the roll group A is driven, and the roll 14 is engraved with a hole type suitable for gripping and restraining the outer diameter of the metal tube 16 as shown in the cross section in FIG. It

Reference numeral B is a mandrel speed regulating device composed of a pair of rolls 15 which is a group of rolls and grips and restrains the mandrel 17 so as to be movable in the axial direction thereof. Each roll pair constituting the roll group B is driven, and as shown in the cross section in FIG.
15 is engraved with a hole type suitable for restraining the mandrel 17.

Next, the procedure for carrying out the present invention will be described in detail with reference to FIG.

Step (a) in FIG. 3 shows a state in which the mandrel 20 is released from the device 13 that grips the mandrel shaft end and controls the speed immediately before the end of rolling in the rolling mill train 18. At this time, the metal tube 19 and the mandrel 20 are partially fitted in the axial direction.

Step shown in FIG. 3 (b): After the tip of the metal tube has passed the point,
The metal pipe 19 is given a constant speed by each roll pair 14 as it passes through each roll pair 14 that constitutes the roll group A.

Steps shown in FIGS. 3 (c) and 3 (d): The mandrel 20 existing after the tail end of the metal tube 19 passes through the point, and then the metal tube 19 is reached.
In order to avoid the above, each roll pair 15 constituting the roll group B that has been retracted in the radial direction of the metal pipe in advance is sequentially displaced toward the center of the metal pipe radial direction, comes into contact with the mandrel, and roll pair
The mandrel 20 is given a smaller axial velocity than the metal tube 19 by controlling the rotation speed of 15.

Step shown in FIG. 3 (e): When the tail end of the metal tube 19 reaches a point (position of the second roll pair 14 in the roll group A in the embodiment shown in FIG. 3), the mandrel 20 is Completely pulled out of metal tube 19.

Steps shown in FIGS. 3 (f) and (g): The roll 14 of the roll group A and the roll 15 of the roll group B are retracted in the radial direction of the mandrel in order to carry the mandrel 20 out of the line, and then the mandrel. 20 is carried out of the line.

(Effects of the Invention) Since the present invention is configured and operated as described above, the mandrel is taken out of the metal pipe immediately after rolling the metal pipe and is carried out of the line, and the rolling mill row is Since it is open to the rolling of the subsequent metal pipes, the mandrel can be removed and the subsequent rolling of the metal pipes can be carried out in parallel at the same time. Since the mandrel can be pulled out smoothly from the metal pipe, scratch quality is not generated on the inner surface of the metal pipe, the quality of the metal pipe is improved, and the heat load due to contact between the mandrel and the high temperature metal pipe is reduced. This has the effect of improving the durability of the mandrel.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an equipment row when carrying out the present invention, and FIG. 2 is a diagram showing a cross section of a roll pair in roll group A and a roll pair in roll group B shown in FIG. 1,
FIG. 3 shows a work procedure for carrying out the present invention, and FIG.
The figure shows two conventional drawing methods in a mandrel mill.
It is a figure which shows (a) and (b). 1,6,12,18: Mandrel mill, 2: Extractor, 3,8,19: Metal tube, 4,9,20: Mandrel,
5, 10, 13: Mandrel speed control device, 7: Stopper,
11, Mandrel restraint device, 14, 15: Roll, 16: Metal tube, 17: Mandrel.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideki Tokita Inventor Hideki Tokita 1-1-1 Edamitsu, Hachimanto-ku, Kitakyushu, Fukuoka Inside Nippon Steel Co., Ltd. Third Technical Research Institute (56) Reference Japanese Patent Publication No. 55-36403 ( JP, B2)

Claims (1)

[Claims] 1. A rolling mill train comprising a plurality of rolling mills of each individual drive type arranged in series, a metal pipe having a mandrel fitted in the hollow portion thereof, and a mandrel having a predetermined axial velocity. One or more mandrel speed control devices for gripping the mandrel following the tail end of the rolled metal pipe and controlling the axial speed of the mandrel after the rolling device for rolling while controlling the value to a value, and the metal after rolling. One or more metal pipe speed regulating devices for gripping the pipe and regulating the axial speed thereof are provided in this order, and immediately after the completion of rolling, the mandrel in the rolling mill train is released from the control of the axial speed thereof, The metal pipe with the mandrel still fitted is discharged from the rolling mill train, and the rolling mill train is opened for the rolling of the subsequent metal pipe, and the metal pipe with the mandrel fitted is used to control the metal pipe speed. And also the metal tube It is possible to pull out the mandrel from the metal tube by gripping the mandrel protruding in the rolling mill row side with the mandrel speed control device in the fitted state and making the axial speed of the metal tube larger than the axial speed of the mandrel. Characteristic is a mandrel drawing method in a mandrel mill.