JPS5939215B2 - Method for manufacturing heat exchanger tubes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a heat exchanger tube, and more particularly, to a method for manufacturing a heat exchanger tube for gas condensation which is relatively easy to process and exhibits a high heat transfer effect.

As a means to improve the heat transfer performance of heat transfer tubes for gas condensation,
It is believed that increasing the ratio of the inner and outer areas of the tube is most effective.

For this reason, many of the techniques for improving condensing heat exchanger tubes involve increasing the ratio of the inner and outer areas, and one known technique is to form fins on the outer surface of the tube by rolling the raw tube. .

Since this technique increases the surface area of the tube's outer surface by forming fins, it is considered an effective means for improving heat transfer performance.

However, with the conventional rolling method, there are restrictions on the pitch, height, width, etc. of the fins even when the shape is simple, making it difficult to sufficiently increase the ratio of the inner and outer areas of the tube, and also having the disadvantage of low productivity. be.

Therefore, currently, due to productivity and manufacturing costs,
The reality is that fins of low height, which are relatively easy to mold, are formed, and the heat transfer performance is satisfied even though it is unsatisfactory.

However, since improving the heat transfer performance is essential to improving the performance of heat exchanger tubes, it is essential to develop a new manufacturing method for heat exchanger tubes to achieve this goal.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a method for easily and highly efficiently manufacturing a heat exchanger tube with excellent heat transfer performance and a high tube/outside area ratio. is trying to develop.

The structure of the present invention that has achieved these objects is as follows: (1) A process of forming a spiral protrusion on the outer periphery of the raw tube, which is inferior to pressing two rolling tools; (H) A rolling process with a sharp tip; Step of pressing a tool against the top of the raised portion to form a cut with a V-shaped cross section; ①: Pressing a rolling tool that fits into the groove between the raised portions into the groove, and forming the raised portion successively thinner and higher. Step (2): Using a disc-shaped rotary tool with a sharp tip, inserting its cutting edge into the notch and relatively rotating the rotary tool, the cutting edge moves the protrusion into the notch. The gist lies in the combination of the steps of cutting and splitting it into a Y-shaped cross section.

The configuration and effects of the present invention will be explained below based on the drawings which are examples, but the following are only the most typical examples, and it is of course possible to carry out the implementation with appropriate changes in accordance with the spirit of the preceding and following. It is possible.

Figures 1 and 2 illustrate the method of manufacturing a heat exchanger tube according to the present invention, and Figure 1 shows a process of rolling forming a spiral fin F having a crack K approximately at the center of the raw tube. FIG. 3 is a partially cutaway side view.

The rolling roll 1 maintains a parallel relationship with the tube axis of the tube 2 and obliquely crosses the axis 3 so as to have a slight lead angle with respect to the tube axis of the tube 2.
However, in the figure, for convenience, the tube axis of the base tube 2 and the axis 3 are shown.
are expressed in parallel.

In the front half of the rolling roll 1, there is a roll 1 with a relatively narrow tip width.
A is provided at a fixed pitch, and a roll 1b with a sharp tip is arranged between them, and this part presses the raw pipe 2 to form a raised part A while cutting the top part approximately in the center. Groove B
form.

Here, the figure shows cut groove forming roll (roll with sharp tip) 1
Although two grooves B are shown, in some cases only one groove B may be provided, or three or more grooves B may be provided to form successively deeper grooves B.

In the rear half of the rolling roll 1, there are provided fin-forming rolls 1 c ylc . . . which have the same pitch as the roll 1a and which gradually become wider and taller toward the rear.

In this portion, the raised portions A are successively raised to a narrow pressure, and the raised portions A are formed to be successively taller and wider, thereby forming a spiral fin F with a crack K in the center.

At this time, the fin forming roll 1 c t 1 c t・
The number of ... is not particularly limited, but in order to carry out rolling smoothly without forcing it, it is preferable to use four or more and gradually increase the processing rate.

In addition, in the illustrated example, the fin forming rolls 1c,
1 cy... was constructed to have a wide width and a large diameter so that it gradually bites into the tube wall of the raw pipe 2, but it was also possible to use fin forming rolls with approximately the same diameter and slightly tilt the shaft 3. It is also possible to make it gradually bite into the pipe wall.

In this case, the axes of the fin forming rolls are the rolls la, Ib.
The shafts of the rolls 1a and 1b with the same diameter may be separated from the shaft of the rolls 1c and 1b, or they may share the same inclined shaft as shown in the figure.
It is also possible to set it in gradually in the same way as...

The cracked fins F thus formed are themselves taller and thinner than conventional fins, and can provide a considerably high tube-outside area ratio.

However, in the present invention, the cracked fins F are split open in order to further increase the tube-outside area ratio.

This process is as shown in Figure 2 (longitudinal cross-sectional view of main parts).
One or two guide rollers located behind the guide roller Id (which can also be used in common with the last fin forming roll 1c)
This is carried out using more than 1 (in the figure, 2) split rolls 1e.

That is, the split roll 1e has a sharp tip with a predetermined apex angle, and is arranged so as to fit into the crack K in the center of the fin F. By fitting the tip into the crack K, the fin F can be moved from side to side. split open.

As a result, as shown in FIG. 3 (a partially sectional perspective view), a large number of spiral fins F having a Y-shaped cross section are formed on the outer periphery of the blank tube.

In the above description, the grooved fin forming roll groups 1a, ib
, we have shown a method in which processing is performed using Ic and split roll groups 1d and 1e at separate locations, but since they are all placed together on the same axis and can be performed continuously in one step, the work is simple and extremely efficient. It is true.

The heat transfer tube obtained in this way has spiral fins F with a wide surface area that are split open in a Y-shaped cross section on its surface, so the tube outside area ratio is extremely large, and it has excellent heat transfer performance. demonstrate.

By the way, when condensing gas using the heat transfer tube obtained above, if the surface tension of the condensed liquid is large, the condensed liquid will accumulate in the grooves between the Y-shaped fins during the heat exchange process, and the heat transfer performance will deteriorate. may hinder.

These difficulties arise when the helical pitch of the fins F is increased to form a wider gap between the grooves, or the degree of splitting of the fins F is reduced (that is, the apex angle of the splitting roll 1e is reduced). can be easily resolved by

As another method for preventing accumulation of condensate, the following method is also effective.

That is, the split-open roll 1e is configured as shown in FIG. 4, and the notches 5 are provided at appropriate intervals to the sharp blade-like portion 4 at the tip, and the other parts are split open in the same manner as in FIG. 2. Do the following.

As a result, the crack is split open in the blade portion 4, but not split open in the notch 5 portion.

As a result, as shown in Figure 5 (partial cross-sectional perspective view), unsplit portions and Y-shaped cross-section split portions are formed alternately at predetermined intervals, and the condensate is absorbed in the unsplit portions. Since stagnation is prevented, deterioration in heat transfer performance due to surface tension can be suppressed.

Moreover, the above-mentioned interval is equal to the blade portion 4 provided on the split roll 1e.
Since it can be freely adjusted by changing the length of the notch 5, it is possible to easily obtain a high-performance heat exchanger tube that corresponds to the surface tension of the condensate.

The present invention is roughly constructed as described above, exhibits various features as shown below, and has great practical value.

(2) By combining a cracked fin forming roll and a split roll, a spiral fin with a large surface area and a Y-shaped cross section can be easily obtained.

In addition, rolling can be performed continuously regardless of the size of the raw tube, making mass production possible and inexpensive. Combined with the improvement in heat transfer performance brought about by increasing the ratio of the inside and outside areas of the tube, it improves heat exchange. The device can be made smaller, lighter in weight, and lower in cost.

■ Since the rolling process combines fin forming rolls and split rolls, the processing accuracy is high and a homogeneous and high-performance heat transfer surface can be provided over the entire surface of the heat transfer tube.

(2) By changing the helical pitch of the fins or deforming the notches of the split roll, it is possible to easily obtain the optimal fins according to the surface tension of the condensate.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view illustrating the process of forming a spiral fin with cracks; FIG. FIG. 3 is a partial sketch illustrating the obtained heat exchanger tube, and FIG. 4 is a front view illustrating another split roller used in the present invention.
FIG. 5 is a partial sketch of a heat exchanger tube obtained using the split roller of FIG. 4. 1... Rolling roll, 2... Plain pipe, 3.
...Shaft, 4...Blade-shaped portion, 5...
Notch, A...Protuberance, B...Notch groove, F...Fin, K...Crack.

Claims (1)

[Claims] 1. A step of forming a spiral-shaped protuberance on the outer periphery of the blank pipe by pressing a rolling tool against the base pipe, H: pressing a rolling tool with a sharp tip against the top of the protrusion, Step of forming a notch with a cross-section of the shape, (2): A step of pressing a rolling tool that fits into the groove between the raised portions into the groove, and rolling up the raised portions one after another thinner and higher; (2): A step of forming a disc shape with a sharp tip. using a rotary tool, inserting its cutting edge into the notch and relatively rotating the rotary tool, and using the cutting edge to split the protruding portion into a Y-shaped cross section by cutting the notch into four; A method for manufacturing a heat exchanger tube, characterized by combining the following.