JPH01107910A - Manufacturing method of metal tube with spiral fins - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a metal tube with spiral fins used as a heat transfer tube in a heat exchanger or the like.

[Prior art]

A method for manufacturing such a metal tube with spiral fins is as shown in FIG. 3 (perspective view).
1 is rotated on its axis and transferred in the axial length direction, and the strip-shaped plate material 32 is continuously supplied so that one edge is in contact with the outer circumferential surface of the strip-shaped plate material 32, so that the strip-shaped plate material 32 is spirally wound around the outer circumferential surface, There is a method of high-frequency welding the joint between the metal tube 31 and the strip plate material 32 (Japanese Patent Laid-Open No. 58-9
No. 715).

When manufacturing a metal tube with spiral fins by such a method, the winding of the strip plate material 32 requires a large driving force for processing, the winding makes it difficult to speed up the processing, and the metal tube 31 is Wrapped band-shaped plate material 32
Tensile stress is generated on the outer periphery side and cracks are likely to occur, and compressive stress is generated on the inner periphery side and wrinkles, folds, and waving phenomena are likely to occur. It is difficult to reliably perform this, and when the obtained spiral finned metal tube is used as a heat transfer tube, there are various disadvantages such as poor heat transfer characteristics due to the unreliable welding of the joint. was there.

On the other hand, a method using plastic working has also been proposed as a method for obtaining a spiral finned metal tube as an integral body. For example, as shown in FIG. 4 (front view) and FIG. 5 (side view showing an enlarged cross section taken along the line V-■ in FIG. 4), three tubes are arranged around the pass line of the hollow metal tube 44. This is a method of cold or hot rolling of the metal tube 44 with rolling rolls 41, 42 and 43 (Plasticity and Processing Vol.
o105 P732).

However, spiral finned metal tubes can be manufactured using the above method only when the material is a soft metal with extremely good workability, such as aluminum or copper; There is a problem in that the above-mentioned method is difficult to apply when the material is ordinary steel, as well as when the material is stainless steel or the like. In addition, when using this method, there is almost no stretching in the longitudinal direction of the tube axis.

Therefore, the present inventors proposed a method for manufacturing a spiral finned metal tube by plastic working, which is different from the above-mentioned method.

That is, as shown in Fig. 6 (front view) and Fig. 7 (side view showing an enlarged cross section taken along the line The rolling rolls 61, 62, 63, which are formed in a plurality in the circumferential direction of the outer circumferential surface at intervals of 3.
The hollow metal tube 64 is rolled between the rolling rolls 61, 62, and 63 by using a cross-type inclined rolling mill with two (or four)
proposed a method in which spiral fins are formed on the outer circumferential surface of the blank metal tube 64 by feeding it hot while placing a mandrel 65 in the hollow part of the tube. No. 60-263439).

According to this method, spiral fins can be formed on the outer peripheral surface of a metal pipe made of common steel.

[Problem that the invention seeks to solve]

However, when manufacturing a metal tube with spiral fins by the above-mentioned method, the flesh of the metal tube pushed away by the rolling rolls mainly flows in the axial direction, and as a result of this flow, fins are formed on the metal tube. while extending in the axial direction.

Therefore, spiral finned metal tubes with thin and tall fins that require the flesh of the metal tube to flow in the radial direction, specifically, fins with an outer diameter larger than the outer diameter of the metal tube, are When manufacturing a metal tube with formed spiral fins (hereinafter referred to as high fin tube),
There was a problem that the above-mentioned method could not be used effectively.

Incidentally, when manufacturing a high-fin tube using the above-mentioned method, it becomes necessary to use a hollow metal tube with an outer diameter as large as the outer diameter of the fins, and it is necessary to use a hollow metal tube with such a large outer diameter. When implementing the above method, the machining energy during inclined rolling increases;
The above-mentioned method is not applied and is usually used in the The conventional method shown in Figure 3 was applied.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method suitable for manufacturing a high fin tube at a low cost.

[Means for solving problems]

The method for manufacturing a spiral finned metal tube according to the present invention includes arranging three or four rolling rolls around a pass line, each of which has a plurality of annular grooves formed in the circumferential direction on its outer peripheral surface for forming fins. A spiral fin in which the metal tube is hot fed between the rolling rolls using a cross-type tilt rolling mill to perform tilt rolling on the metal tube to form a spiral fin on its outer peripheral surface. In the method for manufacturing a metal tube with a metal tube, a metal tube having a small diameter pilot hole bored in the center is used as the metal tube, and a plug is inserted into the pilot hole of the metal tube to perforate the metal tube. The method is characterized in that a fin having an outer diameter larger than the outer diameter of the metal tube is formed by rolling and filling the grooves of the rolling roll with the flesh.

[Effect]

In the case of the method of the present invention, since a metal tube in which a small-diameter pilot hole is drilled is used as the metal tube, machining that requires a large number of man-hours is not required to manufacture the tube, that is, to drill the pilot hole. .

In addition, a plug is inserted into the pilot hole of the metal tube to enlarge the diameter of the tube and the tube is pierced and rolled, so that the flesh of the tube flows in the radial direction. Since it fills the grooves of the rolling roll, by making the groove shape correspond to the desired fin shape, it is possible to easily form a fin having an outer diameter larger than the outer diameter of the metal tube.

〔Example〕

The present invention will be described in detail below based on drawings showing an embodiment of the present invention in the case where the number of rolls is three.

Fig. 1 is a front view showing the main part (roll part) of the apparatus used to carry out the method of the present invention together with the material to be rolled (the roll grooves are omitted), and Fig. 2 is the same as shown in Fig. 1. It is a side view which expands and shows the cross section taken by the line. In the figure, reference numeral 4 denotes a metal tube as a material to be rolled, which has a small-diameter pilot hole 4a bored in its center.The metal tube 4 is transferred in the longitudinal direction, and a plug 5 is inserted into the pilot hole 4a. A set of three cone-shaped rolling rolls 1, 2゜3 installed at the rolling position of the pass line while being inserted.
It is designed to be rolled.

The rolling rolls 1.2.3 each have the same face angle α (see Figure 2), and their axes are inclined so that the shaft ends on the same side face toward the same side in the circumferential direction (this axis line The angle β with respect to the path line of , the intersection angle γ when the roll axis separates from the pass line on the exit side is defined as positive).

A plurality of annular grooves, for example 10 to 20 grooves, are cut in the circumferential direction on the outer circumferential surface of the rolling roll 1.2.3 at appropriate length intervals in the axial direction. Note that the groove may be formed by cutting the outer circumferential surface of an integral roll, or it may be formed by overlapping a plurality of disc-shaped rolls and fitting them onto a single shaft to integrate them. You may.

The positions, intervals, widths, and depths of the grooves differ among the rolling rolls, as partially shown in Figure 2, and the intervals, width, and depth of each rolling roll also differ from each other on the material entry side. It is different towards the exit side.

Note that the positions and intervals of the grooves are determined depending on the height and interval of the fins to be formed and the shape of the plug 5, and the above-mentioned angles α of the rolling rolls are related to these.

β, T, etc. have been determined. In addition, the position and depth of the grooves are changed appropriately from the material input side to the output side, taking into consideration the spiral metal flow during inclined rolling and the metal flow in the radial direction of the fins formed in the gaps between the roll grooves. It is being

Then, a rolling roll 1°2.3 with grooves as described above was formed.
The fins coming out of one of the rolling rolls are guided to the grooves of the next rolling roll and are successively shaped. The width and depth of the grooves are equal to each other between the rolling rolls. Note that the groove depth in each rolling roll is appropriately changed from the entry side to the exit side so that a desired fin height can be obtained at the exit end.

In addition, the inclination angle of each groove with respect to the roll axis in the depth direction is such that when the fins to be formed are perpendicular to the surface of the metal tube, the angle of the center line of the groove is It is tilted at the same angle as the intersection angle γ. That is, when the fins are formed on the material surface so as to be inclined at a predetermined angle, the intersection angle γ and the inclination angle of each groove with respect to the roll axis in the depth direction are made different.

When manufacturing a high-fin tube using a cross-type inclined rolling mill equipped with such rolling rolls, first, the metal tube 4 having a small-diameter pilot hole 4a bored in the center is heated to a predetermined temperature ( For example, in the case of medium carbon steel, it is heated to 1200° C.) and then transferred to the cross-type inclined rolling mill, where the metal blank 4 is pierced and rolled as shown in FIG. That is, when rolling of the metal tube 4 is started in the cross-type inclined rolling mill, the metal tube 4 is rolled by rolling rolls 1 and 2.
．． 3 and then rolled at three locations in the circumferential direction by them, and the diameter of the pilot hole 4a is enlarged by the plug 5 to be pierced and rolled. The flesh of the metal tube 4 flows in its radial direction and fills the grooves of the rolling rolls 1.degree. 2.3. As a result, a desired high-fin tube is obtained from the metal tube 4.

[Numerical example]

The material is the same composition as 5TBA24 and the outer diameter is 65 mm.
A metal tube with an inner diameter of 1011IIlφ (in other words, a pilot hole with a hole diameter of 10 m+aφ was drilled in the center) was inclined rolled under the rolling conditions shown in Table 1, and the fin spacing was A high fin tube with a diameter of 1 m, an outer fin diameter of 75 mm, a fin valley diameter of 38 ma+φ, an inner diameter of 31 wφ, and a wall thickness of 3.5 m was manufactured.

(Margins below) Table 1 As a result, it was possible to easily manufacture the high tube as a single piece, which was conventionally difficult to manufacture by plastic working and was manufactured by plate wrapping and welding.

In addition, in the above example, the roll intersection angle γ was set to 0°, but the roll intersection angle T is not limited to this, and may be set to either a positive or negative angle depending on the specifications and structure of the rolling mill. Can be done. Incidentally, assuming that the roll crossing angle T is 1°,
If the roll face angle α is 6 @ on the inlet side and 1 @ on the exit side, the roll reduction face angle with respect to the pass line will be 5° on the inlet side and 2° on the exit side, as in the above example, and the above example will be applied. A high-fin tube equivalent to the high-fin tube obtained in .

However, the angle of the roll grooves was inclined by 1° toward the entry side so as to be perpendicular to the axis of the metal tube, with the roll crossing angle being 1°.

〔effect〕

As described in detail above, according to the method of the present invention, a high fin tube can be easily made into a single piece by plastic working by piercing-rolling a metal tube with a small-diameter pilot hole drilled in the center using a plug. The present invention has excellent effects, such as being able to obtain the desired results and reducing manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the main parts of the apparatus used to carry out the method of the present invention, FIG. 2 is a side view showing an enlarged cross section taken along the line ■-■ in FIG. 1, and FIG. A perspective view showing a method of manufacturing a metal tube with spiral fins, FIG. 4 is a front view showing the main parts of a rolling machine that is a conventional manufacturing device for a metal tube with spiral fins, and FIG. 5 is a line shown in FIG. 4. Fig. 6 is a front view showing the main parts of a cross-type inclined rolling mill, which is a conventional spiral finned metal tube manufacturing device, and Fig. 7 shows the line ■-■ in Fig. 6. FIG. 1.2.3... Rolling roll 4... Metal tube 4a
...Central hole 5...Plug patent Applicant: Sumitomo Metal Industries Co., Ltd. Agent Patent attorney: Norio Kono

Claims (1)

[Claims] 1. Using a cross-type inclined rolling mill in which three or four rolling rolls each having a plurality of annular grooves for forming fins formed in the circumferential direction on the outer peripheral surface are arranged around a pass line. , in the method for manufacturing a metal tube with spiral fins, in which the metal tube is hot fed between the rolling rolls, the metal tube is subjected to inclined rolling, and spiral fins are formed on the outer peripheral surface of the metal tube. As the metal tube, a tube with a small-diameter pilot hole bored in the center is used, a plug is inserted into the pilot hole of the metal tube, and the metal tube is pierced and rolled to remove its flesh as described above. A method for manufacturing a metal tube with spiral fins, comprising: forming fins having an outer diameter larger than the outer diameter of the metal tube by filling grooves in a rolling roll.