JPS62124023A - Production of metallic pipe with spiral fin - Google Patents

Abstract

PURPOSE:To expand the fin gap of a finished item by arranging the groove for forming a fin at gradually widening intervals from the inlet side of a metallic pipe for the outlet side on the roll of a crossing type inclined rolling mill. CONSTITUTION:A hollow metallic pipe 4 is transferred in the length direction of the pipe shaft with a mandrel bar 5 being inserted therein and rolled by the cross type inclined rolling mill which is equipped with cone type rolling rolls 1, 2, 3. In this case, the position and gap of the groove on the rolls 1, 2, 3 are determined according to the height and gap of the fin to be formed, and the roll face angle alpha, inclination angle beta, cross angle gamma, etc. are decided as well. Moreover, plural annular grooves that the gap is gradually widened toward the outlet side from the material inlet side are formed on the outer peripheral face of the rolling part of the rolling rolls 1, 2, 3. In this way the pipe with a fin that the fin gap is made wider can be manufactured, in case of the hot rolling of the hollow metal pipe.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a spiral finned metal tube using an inclined rolling mill. A hollow metal tube is hot-stretched using a cross-type inclined rolling mill equipped with cone-type rolls to produce spiral fins with desired fin height and spacing, and a fin bottom parallel to the inner surface of the tube. A method of manufacturing a metal tube is provided.

[Prior art]

Metal tubes with spiral fins (
A finned tube (hereinafter referred to as a finned tube) is used, and a rolling method is used to manufacture this finned tube by rolling.

The rolling method uses three rolling rolls 11, 12.1 arranged around the pass line of a hollow metal tube 4 as shown in FIG.
In this method, the metal tube 4 is cold (or hot) rolled in step 3. The shapes of the rolling rolls 11, 12, and 13 are all the same; for example, as shown in Figure 7 (cross-sectional view taken along the line Several dozen rolls with horizontally thin cross-sectional shapes are mounted so that they are coaxial.

In the case of the above method using such a rolling roll, the eighth
As shown in the figure, approximately U-shaped grooves 14 and 14 are formed on the outer surface of the hollow metal tube 4 (see Figure 8 ■) by rolling force in the wall thickness direction (see Figure 8), and then 1J14.14 is rolled down with a disc-shaped roll, and the depth is increased by the force acting in the direction perpendicular to the groove surface (in the direction of the arrow) and processed (Fig. 8 ■, ■ , ■, ■), by moving the amount of metal displaced by this groove processing into the gap between the disc-shaped rolls of the above-mentioned rolling rolls, the fin 1
5 is formed. During this time, almost no stretching occurs in the longitudinal direction of the tube axis.

[Problem that the invention seeks to solve]

Therefore, in the past, there was no stretching as described above, and the size of the fins was determined based on the amount of metal displaced by the disk-shaped rolls, so the inner surface of the tube was placed at the bottom of the fins between the fins. In other words, it is not possible to manufacture a finned tube with a wide fin spacing, and the conventional finned tubes that can be manufactured include, for example, a fin groove bottom diameter of 28 mm.
Crane φ, fin height 8.5mm, fin thickness o,
The fin spacing is as short as 3.5 fins, and the fin height and thickness are made of copper, for example.

15fl each only for soft metals such as aluminum.

There is a relationship that the higher the fin height (approximately 0.2 to 0.5 mm), the thinner the thickness, and there were many restrictions on the dimensions of the finished product.

[Means for solving problems]

The present invention has been made in view of the above circumstances, and involves cutting a plurality of annular grooves on the outer circumferential surface of the rolling part of an inclined rolling roll so that the intervals gradually increase from the material input side to the material output side. To provide a method for producing a finned tube with high fins and long fin spacing by hot elongation rolling a hollow metal tube into which an inner surface regulating tool such as a mandrel bar or a plug is inserted. With the goal.

A method for manufacturing a spiral finned metal tube according to the present invention is a method for manufacturing a spiral finned metal tube by rolling a hollow metal tube, in which the grooves forming the fins are
An intersecting type in which three or four rolling rolls are arranged facing around the pass line, with multiple cuts made in the circumferential direction of the external opening surface of the rolling section at intervals that gradually become wider from the inlet side to the outlet side of the hollow metal tube. The method is characterized in that a hollow metal tube is hot elongated using an inclined rolling mill to produce a metal tube with spiral fins having a fin bottom parallel to the inner surface of the tube.

Effect C] According to the present invention, a cross-type inclined rolling mill enables hot rolling of a metal tube at a high rolling reduction ratio, so that elongation rolling is performed using this,
By cutting grooves at each position of the rolling portion of the rolling roll according to the stretching length, spiral fins having a desired fin height and thickness are formed with the rolling roll while increasing the fin spacing.

〔Example〕

The present invention will be specifically explained below based on the drawings.

FIG. 1 is a front view showing the implementation state of the present invention (grooves are omitted), FIG. 4 indicates a hollow metal tube. The metal tube 4 is transported in the longitudinal direction of the tube axis with the mandrel bar 5 inserted, and a set of three cone-type rolling rolls 1, which are a cross-type inclined rolling mill, are installed at the tube rolling position on the pass line. , 2.3.

The rolling rolls 1, 2.3 have the same face angle α (Fig. 3(a)
1), and its axis line is inclined so that the shaft ends on the same side face in the same direction and on the same side (the angle β of this axis line with respect to the path line is called the inclination angle), and The shaft end is inclined toward or away from the pass line side (
The angle γ of this axis line with respect to the path line is called the intersection angle.

The part where the distance between the outer peripheral surface of the rolling roll 1.2.3 and the pass line is smaller than the radius of the outer periphery of the metal tube 4 passing through it, that is, the outer periphery of the rolling part is shaped like a trapezoid whose opening side is wider. A plurality of annular grooves, for example, three to five grooves, each having an annular cross section, are cut in the circumferential direction and spaced apart by an appropriate length in the axial direction. The position of the groove is 2 intervals.

For the width and depth, see Figure 3 fal, (bl,
(As shown in cl for each rolling roll, the distance between the rolls is different, and the spacing between the rolling rolls is also different in the axial direction.

In accordance with the height interval of the fins to be formed, the interval between two positions of the grooves is determined, and the α, β, γ, etc. of the inclined rolling rolls related thereto are determined. The positions of the grooves differ among the rolling rolls, and for each rolling roll, the spacing gradually decreases from the material input side to the material exit side according to the amount of stretching, so that no fins are left behind. It looks like this.

In other words, the fins coming out of one roll are guided into the grooves of the next roll. The width and depth of the grooves are approximately the same between the rolls, and may be adjusted for each roll as necessary.
For example, it is small on the material input side and large on the material output side.

In addition, when the fins to be formed are perpendicular to the tube surface, the inclination angle of the valley groove with respect to the roll axis in the depth direction is the same as the above-mentioned intersecting angle T, with the groove bottom facing toward the material exit side. Form a slope at an angle.

That is, when the fins are formed on the tube surface so as to be inclined at a predetermined angle, the intersecting angle γ and the inclination angle with respect to the roll axis in the depth direction of the valley grooves are made different.

A finned tube is manufactured using the rolling mill configured as described above in the following manner.

First, the hollow metal tube 4 is heated in a heating furnace (not shown) to a predetermined temperature, for example, 1100° C. in the case of medium carbon steel, and then transferred to a cross-type inclined rolling mill having rolls as described above. As a result, the metal tube 4 is rolled as shown in FIG.

FIG. 4 is a diagram showing the process, and the arrow in the diagram indicates the direction of the load applied to the metal tube 4. When the IIN skew rolling mill metal tube 4 (see Fig. 4@) starts rolling, the metal tube 4 is rolled by the rolling roll 1. 2. 3 and then rolled at three locations in the circumferential direction (Fig. 4
), it moves forward while rotating around its axis. For this reason,
The subsequent rolling is performed in a spiral manner, and the rolled metal tube 4 advances to the roll exit side where the interval between the pass line and the rolls is narrow.

Then, sequential rolling with three rolls (Fig. 4 ■, ■
), the inside of the rolled portion is stretched in the axial direction, thereby widening the fin spacing. The roll is designed so that the grooves that contribute to the next rolling are located in the fin parts where the distance is widened, so not only will no fins be left behind, but the fins will be taller and the fin spacing will be wider. .

Accordingly, the present invention allows for the production of taller, more widely spaced finned tubes. Note that since the fin spacing is affected by the rolling reduction rate, the outer diameter and inner diameter of the metal tube used are determined to predetermined dimensions.

Further, the height of the fins can be adjusted by adjusting the fin spacing, the fin thickness, the amount of stretching, etc.

Figure 5 shows a metal tube with an outer diameter of 5Qmφ, a wall thickness of 14mmL, and a material of 345C, an outer diameter of 30111φ and a material of 30
It is an external view showing a high fin tube manufactured by inserting an M440 mandrel bar and hot rolling with a fin spacing of 20 u, an outer diameter of 60 mm, a fin bottom diameter of 40 n, and an inner diameter of 301 m. The manufacturing conditions are: roll inclination angle β: 9°5, crossing angle T: 3", roll rotation speed 100
rpm, rolling temperature: 1100°C, roll material: 30
It is M440. Further, the roll used had a face angle α=15.5° and various dimensions as shown in FIG. 3.

As can be understood from this figure, in the case of the present invention, it was possible to manufacture a high fin tube with a fin spacing of 20 mm, which was impossible to manufacture by conventional rolling.

〔effect〕

As described in detail above, in the case of the present invention, since the metal tube can be elongated and rolled, a surface parallel to the inner surface of the tube can be formed at the fin bottom, which means that the fin spacing can be increased. The present invention has excellent effects, such as being able to adjust the thickness, height, etc. of the fins by adjusting the size of the grooves formed on the rolling rolls, and thus making it possible to manufacture finned tubes with fin spacings suited to the intended use.

[Brief explanation of drawings]

FIG. 1 is a front view showing the implementation state of the present invention, and FIG.
Figure ■ - A side view showing a partially enlarged cross section along the shoreline, Figure 3 is the profile of the rolling roll, Figure 4 is a detailed explanatory diagram of the present invention, Figure 5 is the fins manufactured according to the present invention. External view of the tube, 6th. 7. FIG. 8 is an explanatory diagram of the content of the prior art. 1. 2. 3...Rolling roll 4...Metal pipe special
Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent Attorney
Noboru Kono Calculation 1 Day Winter 2 Illustration Calculation 3 Figure ■ ■ ■ ■ Calculation 4 Figure β etc. C

Claims (1)

[Claims] 1. In a method of manufacturing a spiral finned metal tube by rolling a hollow metal tube, the grooves forming the fins gradually widen from the inlet side of the hollow metal tube toward the outlet side. A hollow metal tube is hot drawn using a cross-type inclined rolling mill with three or four rolling rolls facing around the pass line and having multiple cuts in the circumferential direction of the outer peripheral surface of the rolling section. A method for manufacturing a spiral finned metal tube, which comprises rolling and manufacturing a spiral finned metal tube having a fin bottom parallel to the inner surface of the tube.