JPS6241815B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a method for manufacturing a heat exchanger tube with helical fins in which holes are formed in the fins at appropriate intervals.

Heat exchanger tubes with perforated helical fins are known as high-performance finned heat exchanger tubes, but conventionally, this type of heat exchanger tube was made by punching a strip of material for the fins to form holes, and then rolling the holes into tubes. Because the material was manufactured by wrapping it around the material, chips from the punching process could enter the machine, causing malfunctions, and the punching burrs could catch on the material in the rolling mill, causing other problems. Moreover, there was a drawback that the punched material was wasted.

The present invention solves the above-mentioned problems of the prior art, and therefore, the purpose of the present invention is to eliminate the problems caused by chips and burrs, and to preferably provide a heat exchanger tube with perforated helical fins that eliminates waste of material. The object of the present invention is to provide a method for manufacturing the same.

In order to achieve the above object, the feature of the method for manufacturing a heat exchanger tube with helical fins according to the present invention is that punching is not used, but instead, a part of the strip material that is the fin material is cut at an appropriate pitch, and at that time, the material is pressed. Return the bent part to its original shape and make it into a flat cut material.
When the material is tapered by a pair of rolling rolls and wound around a tube, the cuts are widened by the rolling.

Next, a method for manufacturing a heat exchanger tube according to the present invention will be explained with reference to the drawings. FIG. 1 schematically shows all the steps in the method for manufacturing a heat exchanger tube according to the present invention. Cutting at appropriate pitches is performed using a press 1 or a press-bending device. The shape of the cut may be arbitrary, and the area of the strip material in which the cut is made does not need to be particularly limited. FIG. 2 shows a state in which a cut 11 is made in a part of the strip material 10, and in this example, the cut 11
is in the shape of an arc. The cut 11 is formed in the middle part of the strip material 10 other than the edges on both sides, but it is preferable that the cut is formed in the middle part in this way. As shown in FIG. 2A, the edge of the cut is slightly pressed and bent as the cut is formed, but since it is not punched, no chips are produced.

The next step is to pass the partially cut strip 10 between a pair of rolls 2 and 3, and return the bent portion to its original position to create a flat cut. It is to be used as a material. FIG. 3 shows the state of the strip material 10 after passing through such a pair of rolls, and in this state, the cut 11 is a linear cut with no width as shown. This roll processing corrects the burrs that were created at the cut portions in the previous stage, so that they do not affect the subsequent processing steps. Next, the strip material 10 is introduced into a pair of rolling rolls 7, 8 while being guided by an appropriate number of guide rolls 4, 5, 6.

As shown in FIG. 4, the cut material made flat by the pair of rolls 2 and 3 is tapered by rolling rolls 7 and 8, and is continuously curled and wound around a pipe (not shown). It becomes a heat transfer tube with helical fins. 10 in FIG. 4 indicates such a helical fin. At this stage, in the present invention, as clearly shown in FIG.
A rolling roll is used in which the roll diameter of the portion 7a in contact with 1 is made slightly smaller than the roll diameter of the other portion 7b. Therefore, the rolling force is smaller in the relatively small-diameter portion 7a of the roll 7 than in the other portions, and as in the illustrated embodiment, the diameter of the portions 7b at both ends of the roll 7 is larger than that of the portion 7a. Therefore, normal rolling force acts on both end portions 7b.
Therefore, a large rolling force is applied to the edge portions on both sides of the strip material 10, causing a large elongation in that portion.
The stretching force pulls the middle portion where the cut 11 is located, so the cut 11 is widened and a hole is formed. Figures 6 and 7 show the helical fin 10 in which the cuts have been widened to form holes 11, and when the cuts 11 have been widened, they play the same role as the holes in the conventional fins. Needless to say, it can be achieved. In addition, in FIG. 5, a small diameter part is formed on the rolling surface of one of the small diameter rolls 7 to weaken the rolling force, but such a small diameter part may be provided on the other roll 8 or both. It may be applied to the rolling roll.

As mentioned above, in the method for manufacturing a heat exchanger tube according to the present invention, since the strip material 10 is not punched, no chips are produced, and therefore there is no wastage of material, and the burrs when forming the cuts by cutting are removed from the roll. Since they are corrected by machining, chips and burrs do not cause problems.
Therefore, the manufacturing process can be carried out smoothly, and the process from forming the cut to winding the fins by tapered rolling can be carried out continuously in a series of steps, so that productivity can be improved.

Therefore, according to the present invention, there are no problems associated with chips or burrs, materials can be saved, and a high-performance perforated helical fin heat exchanger tube can be manufactured with high productivity.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing the entire process of the method for manufacturing a heat exchanger tube according to the present invention, Fig. 2A is a plan view of a strip material that has been cut in the first stage of the invention, and Fig. is a cross-sectional view taken along line A-A in Figure 2A, Figure 3A is a plan view of the strip material with the cut portion flattened by roll processing, and Figure 3B is a cross-section taken along line B-B in Figure 3A. Fig. 4 is a partially cross-sectional side view of a rolling roll for tapering a strip, Fig. 5 is an enlarged view of a portion of Fig. 4, and Fig. 6 is a roll produced according to the present invention. FIG. 7 is an end view of the heat exchanger tube taken along the line C-C in FIG. 6.
It is an enlarged sectional view taken along. In the figure, 1...press, 2, 3...roll, 7,
8... Rolling roll, 10... Strip material, 11... Cut in strip material.

Claims (1)

[Claims] 1. A step of cutting a part of the band material, which is the fin material, at an appropriate pitch using a press or the like, and returning the bent portion due to the cutting to its original position by roll processing to make a flat cut. the step of forming an accessory material, and the step of making the roll diameter of the part of the rolling surface of one or both of the pair of rolls that is in contact with the cut of the strip material slightly smaller than the roll diameter of the other part; A method for manufacturing a heat exchanger tube with helical fins, comprising the step of tapering the cut material with a rolling roll, thereby widening the cut, curling the material, and winding the cut material around a tube. 2. The method of manufacturing a heat exchanger tube with helical fins according to claim 1, wherein the cut is formed in an intermediate portion of the band material other than the edges on both sides.