JPH0741522Y2 - Small diameter electric resistance welded pipe manufacturing equipment - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a thin electric resistance welded pipe manufacturing apparatus, and particularly to a thin diameter electric resistance welded pipe manufacturing apparatus which is optimal when the material is highly ductile in resistance tension.

[Conventional technology]

In the conventional small-diameter electric resistance welded pipe manufacturing apparatus, while the metal hoop is passed through a molding machine to form a pipe, the welded joint is heated by a heating mechanism of a welding machine, such as an induction heating means or a direct current resistance heating means. Then, it passes through a pair of squeeze rolls, pressure welds the heated joints sequentially to form a metal tube, and the beads produced during welding are cut with a bead cutter, and subsequently reduced in diameter and sized by a rolling mill, and then It is configured to be wound or cut into a predetermined length.

At the time of reducing and sizing the metal pipe by the rolling mill of the above manufacturing apparatus, the tension is configured to be reduced while applying a tension to the metal pipe, and thus this tension spreads from the rolling mill side to the metal pipe being welded. Therefore, since it is not possible to set the squeeze roll pair to a fixed upset amount with respect to the metal tube,
As disclosed in Japanese Patent Laid-Open No. 36-4362, a side guide roll pair is provided between a squeeze roll pair and a rolling mill, and a pressing force is applied to the metal pipe by the side guide roll pair to spread the above tension. It is conceivable that the desired upset amount is secured as the above-mentioned upset amount by shutting off.

[Problems existing in conventional technology]

However, in the above technique, the bead formed so as to project outward in the radial direction of the metal pipe at the seam sequentially pressed and welded by the squeeze roll pair passes while being pressed against the side guide pair, and thus the bead is pressed. Since the pressure is concentrated on the bead (unbalanced pressure is applied), the metal pipe after passing through the pair of side guide rolls is distorted or the welded part of the metal pipe is cracked more frequently. However, there is a problem that the manufacturing quality of the small diameter tube is unstable and deteriorates.

[Purpose of device]

The present invention has been made to solve the above-mentioned conventional problems, and prevents the pulling force required for diameter reduction and sizing by a rolling mill from spreading to the squeeze roll pair, while improving the welding quality of small diameter pipes. It is an object of the present invention to propose a small-diameter electric resistance welded pipe manufacturing apparatus capable of obtaining high-quality products.

[Constitution of device]

The present invention, which solves the above-mentioned problems, is designed to form a metal hoop through a forming machine, and sequentially weld the joints formed by pipe forming with a squeeze roll pair (SQ, SQ) of a welding machine to form a metal pipe (W ), And then apply tension to the metal pipe (W)
In a small diameter electric resistance welded pipe manufacturing apparatus in which the bead generated during the welding is cut by the bead cutter (BC) and then reduced in diameter by the rolling machine while running on the rolling machine, the squeeze roll pair (SQ, SQ) And bead cutter (BC)
And a peripheral surface of each side guide roll formed with a flat (f) at both end edges and a concave arcuate groove (u) of a predetermined width at the center. The flat portion (f) of the pair of side guide rolls (SGR, SGR) is separated by an interval that allows the bead (b) generated at the joint of the metal pipe (W) to pass immediately after welding. The groove portions (u) are pressed against each other so that the metal pipe (W) can be reduced in diameter, and the degree of the diameter reduction by the groove portions (u) depends on the tension applied to the metal pipe (W) by the rolling mill. Is to the extent that it does not spread to the squeeze roll pair (SQ, SQ).

[Function of device]

According to the present invention, the concave arcuate groove portion of the side guide roll pair presses the metal pipe passing through the squeeze roll pair so as to be capable of reducing the diameter, and the tensile force applied to the metal pipe from the rolling mill side propagates in the direction of the squeeze roll pair. It is possible to secure a desired upset amount by preventing the above, and furthermore, the bead generated on the metal tube is guided by the flat portion of the side guide roll pair and is applied to the concave arcuate groove portion of the side guide roll pair. By preventing this, it is possible to prevent concentrated pressure contact force from being applied to the metal pipe W, so that the welding quality of the small diameter pipe is stabilized and improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 (a) and 1 (b).

FIG. 1 (a) shows an essential part of an embodiment of a small-diameter electric resistance welded pipe manufacturing apparatus according to the present invention. W is a metal pipe formed by a molding machine (not shown), and C is a welding machine. The induction heating coil, BC, which is a heating mechanism, is a bead cutter.

SQ, SQ are a pair of squeeze rolls of the welding machine, and the feed passage is sandwiched between the induction heating coil C and the bead cutter BC of the feed passage of the metal tube W traveling according to the arrow in FIG. 1 (a). Are arranged opposite to each other with their axes parallel to each other.

Fig. 1 (a), which is a pair of SGR and SGR side guide rolls.
Between the pair of squeeze rolls SQ, SQ and the bead cutter BC on the feed passage of the metal tube W traveling according to the arrow, the feed passage is sandwiched and the axes are arranged in parallel with each other.

As shown in the side view in FIG. 1 (b), the pair of side guide rolls SGR, SGR have a peripheral surface shape in which both end edges are flat portions f, and the center is a concave arc groove portion u of a predetermined width. Has been formed. The pair of side guide rolls SGR, SGR are arranged so that the flat portions f, f face each other with a gap A slightly larger than the width of the bead b generated during welding, and at this time, the respective groove portions u, u. The peripheral surfaces of the two are opposed to each other with a space in pressure contact with the metal pipe W passing between them. That is, when the outer shape of the metal tube W before passing through the space formed by the both groove sections u is d1 and the outer shape after passing the metal tube W is d2, the metal tube w is reduced to a relationship of d2> d1. The metal pipe is pressed against the metal pipe so as to be possible.

Therefore, the metal tube W heated by the induction heating coil C and sequentially welded to the seam by the squeeze roll pair SQ, SQ has a metal pressing force directed inward in the radial direction between the side guide roll pair SGR, SGR. While passing through the pipe W almost all around, it goes to the bead cutter BC. At this time, the bead part b passes through the flat parts f and f, and the bead b is cut by the bead cutter BC and travels to the rolling mill. .

Further, the squeeze roll pair SQ, SQ is desirable because the contact time with the metal tube W is long because it is necessary to secure a desired upset amount with respect to the metal tube W.
As described above, the roll diameter is larger than the side guide roll pair SGR, SGR.

In this way, the metal tube W passes between the side guide roll pairs SGR, SGR while receiving a pressing force, so that the tension applied to the metal tube W from the rolling mill side is reduced by the side guide roll pair. SGR, SGR prevents squeeze roll vs. SQ, SQ from spreading to the direction of squeeze roll vs. SQ.
Q and SQ can secure a desired upset amount for the metal tube W.

Further, when the metal pipe W passes between the side guide rolls SGR, SGR, the bead portion b of the metal pipe W has a flat portion f,
Since it is possible to prevent the bead portion b from hitting the groove portions u, u by being guided by f, the side guide roll pair SG
Since it is possible to prevent the groove portions u, u of the R, SGR from contacting each other, the peripheral surfaces of the groove portions u, u of the side guide roll pair SGR, SGR are contacted over substantially the entire peripheral surface of the metal pipe W, Since it becomes possible to apply a pressing force to the metal tube W, it is possible to prevent an unbalanced pressure from being applied to the metal tube W passing between the side guide roll pair SGR, SGR, and thus the side guide roll pair SGR, SGR. Since it is possible to reduce the occurrence of cracks in the welded portion due to the deformed metal pipe W after passing, it is possible to improve and stabilize the welding quality of the small diameter pipe.

Here, FIG. 2 to FIG. 4 show the experimental results to confirm the effect when the side guide roll pair SGR, SGR of the present invention is used. Hereinafter, FIG. 2 to FIG. 4 will be explained. .

FIG. 2 is a tension-pipe diameter relationship characteristic line showing how the magnitude of the tension affects the pipe diameter of the metal pipe W when the tension is applied between the forming machine and the rolling mill. Figure,
Line a uses the side guide roll pair SGR, SGR of the present invention. The vertical axis indicates the reduction ratio (%) of the diameter of the metal tube W and the horizontal axis indicates the distance between the side guide roll pair SGR, SGR and the rolling mill. Tension of (kgf
/ mm ² ). In addition, the line B does not use the side guide roll pair SGR, SGR of the present invention,
The vertical axis represents the reduction rate (%) of the diameter of the metal tube W, and the horizontal axis represents the tension between the squeeze roll pair SQ, SQ and the rolling mill (kgf / mm ² ). In FIG. 2, A ₀ and B ₀ are squeeze rolls and S
When passing through Q and SQ, and Ai and Bi are the longitudinal and lateral diameters of the metal tube W after passing through the squeeze roll pair SQ and SQ.

As is apparent from FIG. 2, when the side guide roll pair SGR, SGR of the present embodiment is used, the diameter reduction ratio of the side guide roll pair SGR, SGR is significantly reduced even if the tension is increased. Without it, it is understood that the side guide roll pair SGR, SGR blocks the spread of the above tension, and thus,
The squeeze roll pair SQ, SQ can secure a desired upset amount for the metal tube W.

FIG. 3 shows the material tensile strength and how the relationship between the tensile strength of the material of the metal tube W and the tensile strength during rolling affects the reduction rate (%) of the diameter of the metal tube W. It is a diagram of the diameter reduction ratio, and is an experimental example in the case where a tension of 20 kgf / mm ² is applied to the metal tube W heated to approximately 400 ° C. during forming welding. The vertical axis shows the diameter reduction ratio (%), and the horizontal axis shows the material tensile strength (kg).
f / mm ² ) on the diagram, side guide roll pair SGR, S
The plots are plotted and compared when GR is used and when it is not used. Line C shows the side guide roll pair SGR, SGR when used, and line D shows the side guide roll pair SGR, SGR not used. The definition of the diameter reduction ratio (%) in FIG. 3 is the same as that in FIG.

As is clear from FIG. 3, when the side guide roll pair SGR, SGR of this embodiment is used, the diameter reduction ratio (%) is almost constant regardless of the tensile strength of the material. Since it is maintained in the range of the ratio (95% to 100%), it is understood that the pressure contact force is applied to almost the entire circumferential surface of the metal tube W.

Further, FIG. 4 shows the relationship between the cracks that occur from the seam surface of the metal tube W as a starting point when the metal tube W is stretched and sized by a rolling mill and the diameter reduction rate (%) of the metal tube W during forming welding. Is a graph of the crack occurrence frequency (number of occurrences per 5 km length after pipe distraction) on the vertical axis and the diameter reduction ratio (%) on the horizontal axis. is there. The fourth
The definition of the diameter reduction rate (%) in the figure is the same as in the case of FIG.

As is clear from FIG. 4, side guide rolls and SGR,
If the diameter reduction rate (%) of the metal tube W before and after passing the SGR is set within the range of 95 to 100%, the crack occurrence frequency can be kept within 1 and usually 1 spool is about 2 km (eg 1.2 mmφ, 20 kg
Since there is no problem in practical use, the degree of cracking is not a problem for practical use, and as described in Fig. 3, side guide roll pair SGR, SGR
When using, regardless of the size of the material tensile strength,
Since the diameter reduction ratio (%) can be easily set within this range (95 to 100%), the frequency of cracking of the metal pipe W is reduced, so that the product quality of the small diameter pipe is stabilized, It is understood that the tensile strength of 40 kgf / mm ² or less has a remarkable effect as compared with the case where the side guide rolls SGR and SGR are not used.

As shown in FIGS. 3 and 4, when a metal hoop having a low resistance tension is used as the material and the metal hoop is extended to a very fine metal tube by a rolling mill, the side guide roll pair SGR,
It is understood that SGR is extremely effective.

Furthermore, the effects on the process and welding quality due to the presence or absence of the side guide rolls SGR, SGR are shown together in the table on the attached sheet. In the seam rolling column in the table, ◎ means no seam rolling, ○ means almost no, and △ means yes.
In the other columns, ○ means good, and △ means bad.

From this table, the use of side guide rolls vs. SGR, SGR
It is understood that it is effective in improving and stabilizing the welding quality.

[Effect of device]

According to the present invention, the side guide roll pair is disposed between the squeeze roll pair and the bead cutter, and the concave arcuate groove portion of the side guide roll pair presses the metal pipe passing through the squeeze roll pair so as to reduce the diameter. By preventing the tensile force applied to the metal tube from the rolling mill side from spreading to the opposite side of the squeeze roll, a desired upset amount can be secured, and the bead generated on the metal tube can be secured. The flat portion of the pair of side guide rolls is prevented from being applied to the concave arcuate groove portion of the pair of side guide rolls, so that it is possible to prevent concentrated pressure contact force from being applied to the metal pipe W. The welding quality of the diameter pipe is stable and can be improved.

[Brief description of drawings]

1 (a) and 1 (b) are a plan view and a side view, respectively, showing an essential part of an embodiment of the present invention, and FIGS. 2 and 3 are tension-pipe diameter relationship characteristic lines in the apparatus of this embodiment, respectively. FIG. 4 is a diagram showing the relationship between the tensile strength of the material and the diameter reduction ratio, and FIG. 4 is a diagram showing the relationship between the diameter reduction ratio and the crack occurrence frequency. SQ: Welder squeeze roll SGR: Side guide roll BC: Bead cutter u: Groove f: Flat part b: Bead W: Metal tube A: Spacing between flat parts

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Kosuke Baba, 13-346, Aobaoka Minami, Suita City, Osaka Prefecture (72) Inventor, Masami Tano, 13-324, Minami Aoba Hill, Suita City, Osaka Prefecture (56) References Japanese Patent Publication Sho 36-4362 (JP, B1) JP-B-59-50428 (JP, B2)

Claims (2)

[Scope of utility model registration request] 1. A squeeze roll pair (S) of a welding machine is used for forming seams formed by pipe-forming a metal hoop through a forming machine.
(Q, SQ) to sequentially press weld to form a metal tube (W), and then load the bead generated during the welding while running the metal tube (W) on the rolling mill by applying tension to the bead cutter (B).
In a small diameter electric resistance welded pipe manufacturing device that is cut by C) and then reduced in diameter by the rolling mill, the squeeze roll pair (SQ, SQ) and bead cutter (BC)
A pair of side guide rolls, which are arranged with a feed passage between them, and whose peripheral surface shapes are flat edges (f) at both ends and concave arcuate grooves (u) of a predetermined width at the center. The flat portion (f) of the pair of side guide rolls (SGR, SGR) is separated by an interval that allows the bead (b) generated at the joint of the metal tube (W) to pass immediately after welding. And the groove portion (u) press-contacts the metal pipe (W) so as to reduce the diameter. The degree of the diameter reduction by the groove portion (u) is applied to the metal pipe (W) by the rolling mill. A small-diameter electric resistance welded pipe manufacturing apparatus that prevents tension from spreading to the squeeze roll pair (SQ, SQ). 2. The small diameter electric resistance welded pipe manufacturing apparatus according to claim 1, wherein the tensile strength of the metal hoop material is 40 kgf / mm ² or less.