JPH03128106A - Rolling method for inclined drawing of pipe - Google Patents

Abstract

PURPOSE:To obtain a good internal face quality by deciding the moving speed of a mandrel bar and the initial position of the rolling start time under the conditions of reaching the start point of a roll bite part simultaneously with the rear end of a blank pipe and the effective part of the mandrel ber. CONSTITUTION:Movement is started from the rolling start time when the front end of a blank pipe H reaches the start point of a roll bite and is engaged between a thick rolling reduction part 1a and mandrel bar 2. It is decided so that the front end in the moving direction of the effective part of the mandrel bar 2 may reach the terminal of the roll bite part together with the rear end of the blank pipe H. Moreover, the moving speed of the mandrel bar 2 initially positioned as above is decided so that the effective part rear end may reach the start point of the roll bite part simultaneously with the rear end of the blank pipe H. Thus the whole length of the effective part of the mandrel bar is brought into contact with the pipe, there is no part contributing to no rolling of the pipe, priortity for the thermal load and lubricity while under rolling is caused and a high internal face quality can be obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses inclined rolls and a mandrel bar as an inner surface regulating tool in a Mannesmann pipe manufacturing line to reduce the wall thickness of a raw pipe obtained by a piercer, for example. The present invention relates to a method for inclined rolling of pipes.

[Prior art]

The method of inclined stretching and rolling of a pipe, which is carried out to reduce the wall thickness between inclined rolls arranged around the pass line of the pipe and an inner surface regulating tool penetrated inside the pipe, includes the above-mentioned inner regulating tool. A method using a plug as a tool and a mandrel bar
However, the latter method is superior in terms of the quality of the inner surface of the tube after rolling. This is because the plug has a bullet shape and is not moved during rolling, whereas the mandrel bar is columnar and is moved during rolling. This is because the latter has an advantage in heat load and lubricity.

That is, when elongation rolling is performed while moving the mandrel bar in the same direction as the tube, different parts of the mandrel bar sequentially come into contact with the tube being rolled, which provides superiority in the heat load and lubricity. When a product pipe is required to have high inner surface quality, an inclined stretch rolling method is used in which a mandrel bar is moved at a predetermined speed.

In this inclined stretch rolling method, the inner surface quality can be further improved by increasing the moving speed of the mandrel bar and increasing the length of the mandrel bar that contacts the tube per unit rolling length. Figure 5 is a graph showing the results of measuring the inner surface roughness of the tube obtained by varying the moving speed of the mandrel bar. The vertical axis shows the ten-point average roughness of the inner surface of the tube.

It is clear from this figure that the inner surface quality improves with increasing bar speed ratio, i.e. increasing the speed of movement of the mandrel bar.

However, when a high moving speed is applied to the mandrel bar, a long mandrel bar is required to be positioned inside the tube at the location where the rolling rolls are arranged until the entire length of the tube is rolled. Not the point. In reality, the length of the mandrel bar is limited due to bearing problems and tool costs, so it is necessary to use the mandrel bar of limited length as effectively as possible to meet the above requirements. This has become an important issue for responding to these demands.

6(a) to (C1) are schematic diagrams showing the implementation state of the conventional inclined stretch rolling method. The blank pipe H before rolling is shown on the pass line XX as indicated by the white arrow in the figure. Proceed in the direction shown,
The sheet is stretched between a mandrel bar 2 inserted into the inside of the sheet and rolling rolls 1, 1 arranged around the bus line XX. The inlet side of the rolling roll 1.1 is a thick rolling part 1a composed of an inclined surface that approaches the pass line XX as it reaches the outlet side, and the thick rolling part 1a is formed on the exit side of the thick rolling part 1a. The continuous part is composed of a surface substantially parallel to the pass line X-X, or is a ring part 1b, and
The material is first bitten between the thickness reduction part 1a and the mandrel bar 2, and then held between the reeling part 1b and the mandrel bar 2, and the thickness is reduced by stretching in each part, and the desired thickness is obtained. It is sent out as a thick tube P. That is, the part (roll bite part) of the rolling roll 1 involved in stretching the raw pipe H extends from the position where the biting occurs between the thick rolling part 1a and the mandrel bar 2 to the rear end position of the reeling part 1b. It is between.

Figure 6(a) shows the state at the start of rolling, and Figure 6(C)
is the state immediately before the end of rolling. Conventionally, at the start of rolling, the mandrel bar 2 is positioned as shown in FIG. 6(a), with the front end of its effective part in the advancing direction aligned with the end point of the roll bite part, that is, the rear end of the reeling part 1b. , the tip of the raw tube H reaches the starting point of the roll bite part, and the tip part is bitten between the thick-walled part 1a and the mandrel bar 2 and starts moving, and this mandrel bar The moving speed of tube 2 is determined so that the rear end of the effective portion and the rear end of the blank tube H simultaneously reach the starting point of the roll bite portion, as shown in FIG. 6(C).

As a result, substantially the entire effective portion of the mandrel bar 2 can contribute to rolling, and a pipe P having high inner surface quality can be obtained.

[Problem to be solved by the invention]

However, in this case, the mandrel bar 2 is still moving even after the start of rolling until the front end of the raw pipe H reaches the end point of the roll bite section, that is, the rear end of the reeling section 1b. ), the portion of length Ll corresponding to the moving distance from the front end of the effective part of the mandrel bar 2 to this distance is a portion that does not contact the raw pipe H and cannot contribute to rolling, and is therefore long.

Due to the existence of this non-contributing portion, there was a problem in that there was a limit to the improvement of the inner surface quality of the obtained pipe P.

The present invention was made in view of such circumstances, and τ
It is an object of the present invention to provide a method for inclined stretching and rolling of a pipe, which allows the effective length of the mandrel bar to contribute to rolling, thereby making it possible to obtain as high an internal quality as possible with a mandrel bar of limited length.

[Means to solve the problem]

The method for inclined stretching and rolling of a pipe according to the present invention includes a mandrel bar that is inserted into the inside of the pipe and moves in the same direction at a speed lower than the entrance speed of the cough pipe; In the method of elongation rolling between the roll hide part of inclined rolls arranged around the pass line of the pipe, the moving speed of the mandrel bar and the initial position at the start of rolling are set according to the effective part of the mandrel bar and the roll hide part of the mandrel bar. The front ends of the respective tubes in the traveling direction simultaneously reach the end point of the roll bite part, and
It is characterized in that the determination is made based on the advancing speed of the tube under the condition that the respective rear ends reach the starting point of the roll bite section at the same time.

[Effect]

In the present invention, at the start of rolling, the mandrel bar is
The front end of the effective part of this was located upstream of the end point of the roll bite part, and when the pipe was bit into the roll bite part, it started moving and the front end of the effective part reached the end point of the roll bite part. At the same time, the front end of the tube is positioned so that it reaches the same point, and the moving speed of the mandrel bar, which starts moving from this initial position, is such that the rear end of the effective part of the mandrel bar and the rear end of the tube reach the roll bite area. are determined so that they reach the starting point at the same time.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof. FIG. 1 is a block diagram of an apparatus used to carry out the method for inclined stretching and rolling of pipes according to the present invention (hereinafter the method 15'r)'') of the present invention.

The raw pipe H before rolling progresses on the pass line XX in the direction shown by the white arrow in the figure, and the mandrel bar 2 penetrates inside this and is arranged around the bus line XX. The desired meat II is stretched between the pair of rolling rolls 1, 1
It is sent out as a pipe P having a . The rolling rolls 1, 1 are disposed at a predetermined intersecting angle γ and a predetermined inclination angle β (not shown) with respect to the pass line XX, and are driven by a driving force from a driving source (not shown) to The advancing force of the raw pipe 1 is mainly applied by the rotation of the rolling rolls 1. A day scroll (not shown), a plate, a roller guide shoe, or the like is provided in order to restrict the movement of the roller in the radial direction during rolling.

The mandrel bar 2 is connected to the rolling roll 1 on the pass line XX. 1, and the base end of the retainer 3 is connected to a bar drive section 4 comprising, for example, a motor M and a chain R driven by the motor M. connected. Then the mandrel bar
2 is moved in the same direction as the raw pipe H along the pass line XX in accordance with the operation of the par drive unit 4 transmitted via the retainer 3. The drive source of the bar drive unit 4, in other words, the motor M which is the drive source of the mandrel bar 2, is configured to be driven in accordance with a speed control signal given from the calculation control unit 5, and the motor M obtained by this drive
The rotational speed of is detected by a rotational speed detector 10 attached thereto, and the detection result is given to the arithmetic control section 5 as a feedback signal. As a result, the mandrel bar 2 moves in the same direction as the raw pipe H and the pipe P at a predetermined speed determined by the calculation control unit 5 as described later.

The arithmetic control unit 5 receives the detection results of the rolling loads on the rolls 1 and 1 from the load detector 11.11 attached to the rolling roll 1.1, and the power detector attached to these drive sources (not shown). Detection results of the rolling power are provided from 12, and detection results of the moving position of the mandrel bar 2 are provided from a position detector 13 attached to a part of the retainer 3, for example. Furthermore, the calculation control unit 5 stores the dimensions and advancing speed (inlet speed) of the raw pipe H, the dimensions and advancing speed (outlet speed) of the rolled pipe P, and the rolling roll 1°1.
Various rolling data related to the rolling state, such as the dimensions of each part and the roll spacing, are given in advance from an external input device (not shown).

FIGS. 2(a) to 2(C) are schematic diagrams showing the implementation state of the method of the present invention. As shown in this figure and FIG.
The thickness reduction part 1a is composed of an inclined surface approaching X, and the part continuous to the exit side of the thickness reduction part 1a is:
A ring portion 1b is formed of a surface parallel to the pass line XX. The raw pipe H, which advances on the pass line XX, is first caught between the thick-walled part 1a and the mandrel bar 2, and as it further advances, it is separated between the reeling part 1b and the mandrel bar 2. It is held in between and stretched from the position where the biting occurs to the rear end of the reeling part 1b (roll bite part).

FIG. 2(a) shows the state in which the front end of the raw pipe H has reached the starting point of the roll bite part and is bitten between the thick-walled rolling part 1a and the mandrel bar 2, that is, the state at the start of rolling. FIG. 2(b) shows the state when the raw pipe H has further advanced and its front end has reached the end point of the roll bite section, that is, the rear end of the reeling section 1b. FIG. 2(C) shows a state immediately before the end of rolling, in which the rear end of the raw pipe H has reached the starting point of the roll bite section.

In the method of the present invention, at the start of rolling, that is, as shown in FIG.
When the mandrel bar 2 starts moving at this point and reaches the state shown in FIG. Further, when the state shown in Fig. 2 (C) is reached, the rear end of the effective part reaches the starting point of the roll bite part together with the rear end of the raw pipe H at the same time. The moving speed of the mandrel bar 2 positioned at the initial position is determined as follows.

The above will be carried out as follows. The initial position of the mandrel bar 2 is represented by the protrusion length Lt of the front end of the effective part in the moving direction from the starting point of the roll bite part (see FIG. 2), and the moving speed is represented by (2).

In this case, from the condition that the front end of the effective part of the mandrel bar 2 and the front end of the blank pipe H reach the end point of the roll bite part at the same time, the following equation (1) is valid, and Lt -L-Vt,'
T+ (1) Furthermore, the following equation (2) holds true from the condition that the rear end of the effective part of the mandrel bar 2 and the rear end of the blank tube H reach the starting point of the roll bite part at the same time.

L, = L, +V, ・T2 ... (2) In these formulas (11, (21), L is the length of the roll bite part, L
, is the effective length of the mandrel bar 2.

Also, T1 is the time required for the tip of the raw tube H to pass through the roll bite part, and T2 is the time from when the tip of the raw tube H is bitten by the roll bite part until the rear end is bitten. .

Among these, t and b are values specific to the mandrel bar 2, and T2 can be easily determined from the length of the raw pipe H and its advancing speed (inlet speed). In addition, , is the sum of the length of the part contributing to rolling in the thick rolling part 1a minus the length of the ring part 1b, and the unknown former is the roll spacing distribution in the axial direction in the thick rolling part 1a. , can be calculated from the effective part outer diameter of the mandrel bar 2 and the dimensions of the raw pipe H,
Furthermore, T can be obtained from the calculated roll bite length, the entrance speed, and the exit speed. Therefore, the above (1
) and (2) are the moving speed V of the mandrel bar 2,
and the protrusion length Lt are unknown quantities, resulting in a two-dimensional simultaneous equation 2. For example, the following (
3) The moving speed ■ is determined by the formula, and T z T
I Furthermore, by substituting this into equation (1), the protrusion length Lt representing the initial position of the mandrel bar 2 is obtained.

This calculation is performed in the calculation control section 5 using the rolling data inputted in advance prior to the start of rolling.The calculation control section 5 issues a drive command to the bar drive section 4 and
The protrusion length was calculated using the detection result of step 3 as a feedbank signal.

In order to realize this, the mandrel bar 2 is moved and its initial position is set. After this, when the raw pipe H is bitten into the roll bit part and becomes the state shown in FIG. It recognizes this, issues a speed control signal to the bar drive unit 4, uses the detection result of the rotational speed detector 10 as a feedback signal, and moves the mandrel bar 2 at the above-mentioned moving speed.
It operates to move at step 5. With the above operation,
As shown in FIGS. 2(a) to (C), the mandrel bar 2 has all its effective parts in contact with the raw pipe H at some point during rolling, and has no part that does not contribute to the rolling of the raw pipe H. Since no contributing parts are formed, it is clear that the heat load and lubricity during rolling are excellent, and a pipe P having high inner surface quality can be obtained.

FIG. 3 is a graph showing the measurement results of the inner surface roughness of the pipe P obtained by implementing the method of the present invention, and FIG. 4 is a similar graph of the pipe P obtained by the conventional method shown in FIG. It is.

All of these have a diameter of 350mm and a body length of 200mm.
mm rolling roll 1,1 and effective length (= L-) 215
In an inclined stretching rolling mill equipped with a mandrel bar 2 of 2 mm, the outer diameter is 60 mm, the wall thickness is 8 mm, and the length is 30 mm.
0mm.

This is the result of stretching and rolling 10 pieces each of 500 mm and 600 mm (30 pieces in total) under conditions of an entry speed of 50 mm/sec and a stretching ratio of 2.0. When comparing FIG. 3 and FIG. 4, there is clearly a significant difference between the two, and it can be seen that the internal quality of the product tube is improved by implementing the method of the present invention.

In this example, the case where the mandrel bar 2 is supported on the exit side of the rolling roll 1.1 has been described, but it goes without saying that the method of the present invention can also be applied in the case where the mandrel bar 2 is supported on the entry side. stomach.

In addition, a detector for input speed and exit speed is provided, and based on the detection results during rolling, the above (1) 2 and (
2) By updating the values of times T1 and T2 in the equation and moving the mandrel bar 2 at a moving speed Vb that is sequentially updated using these values, the rear end of the effective part of the mandrel bar 2 at the starting point of the roll bite part and the rear end of the effective part of the mandrel bar 2 are The alignment with the rear end of the blank tube H can be made even more reliable.

〔effect〕

As detailed above, in the method of the present invention, the entire length of the effective part of the mandrel bar is in contact with the pipe, and there is no part that does not contribute to the rolling of the pipe, compared to the conventional method in which there is a non-contributing part. Further advantages with respect to thermal loads and lubricity result, resulting in the highest possible internal quality for a mandrel bar of limited length, and the same internal quality for a mandrel bar of shorter length than before. The present invention has excellent effects such as being able to be guaranteed with a mandrel bar.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the apparatus used to implement the method of the present invention, Fig. 2 is a schematic diagram showing the implementation state of the method of the present invention, and Fig. 3 is a measurement of the inner surface roughness of a tube obtained by the method of the present invention. A graph showing the results; FIG. 4 is a graph showing the measurement results of the inner surface roughness of the tube obtained by the conventional method; FIG. 5 is a graph showing the correlation between the moving speed of the mandrel bar and the inner surface roughness of the product tube; FIG. 6 is a schematic diagram showing the implementation state of the conventional method. 1... Rolling roll la... Thick wall rolling part 1b...
・Reeling part 2... Mandrel bar 4... Bar drive part 5... Arithmetic control part H... Raw tube P.
··tube

Claims (1)

[Claims] 1. A mandrel bar that penetrates the inside of a tube that is moving at a predetermined speed and moves in the same direction at a lower speed than the entrance speed of the tube, and a pass line for the tube. In the method of elongation rolling between the roll bit part of inclined rolls disposed around the mandrel bar, the moving speed of the mandrel bar and the initial position at the start of rolling are set according to the effective part of the mandrel bar and the progress of each of the pipes. A tube characterized in that the direction is determined based on the traveling speed of the tube under the condition that the front end simultaneously reaches the end point of the roll bite section and the respective rear ends simultaneously reach the start point of the roll bite section. Inclined stretch rolling method.