JPS5949517B2 - Heat exchanger with fins - Google Patents

Description

Detailed Description of the Invention In recent heat exchangers, tubes are becoming thinner in order to reduce heat transfer resistance and cost. In exchangers, this trend toward thinner tubes has made it even more difficult to bend the tubes.

That is, when the tube is bent, the cross-sectional shape at the bent portion is deformed from a circular shape, leading to an increase in the flow resistance of the fluid within the tube and eventually leading to cracking and collapse phenomena. This phenomenon of tube collapse occurs when the tube body is bent. At the bend, there must be an elongation on the outside of the tube and a compression on the inside of the tube. However, if the amount of elongation on the outside of the tube is small, the outer periphery of the tube cannot maintain a circular cross section. This was caused by the wrinkles being unevenly generated on the inside of the tube due to shrinkage. That is, as shown in FIG. 1a, the inside of the tube 1 had large wrinkles and became constricted, and as shown in FIG. 1b, the cross section was significantly crushed. A conventional method to improve this drawback is to use only the straight parts of the heat exchanger, and connect the bent parts to the so-called U-bent pipes, which were previously manufactured by another method, by low-temperature welding. There is a method of inserting Z gold into the tube and bending it.
The former has low productivity and some reliability problems.

The latter requires a complicated process and is not suitable for mass production, and if the fins 2 are wrapped around the outer circumference of the tube 1, the tube 1 will bend when bent.
Even if the bent part of the pipe body 1 is brought into tight contact with a bend Z (not shown) having an arbitrary bending radius on the inside and bent, it will be affected by the presence of the fins 2 and stress will be applied to one stress point inside the pipe body 1. It's easy to concentrate and then take turns. Furthermore, the fins 2 on the inside of the tube 1 are all crushed as shown in Figure 2, and the outside of the tube 1 is crushed due to insufficient elongation of the tube 1, and the fins come off from the adhesive part. There are drawbacks such as reduced heat transfer performance and little expectation of heat exchange at bent portions. Therefore, as a method of resolving the difficulty in bending due to the presence of the fins, as shown in FIG. 3, there is a method of bending the pipe body 1 as shown in FIG. 4 without wrapping the fins 2 only around the part that is to be bent. Alternatively, as shown in Fig. 5-1, a method has been considered in which only the fins in the portion to be bent are removed using a cutter or other method, and the fins are bent in the state of a pipe body.
The former method lacks productivity because the fins 2 cannot be wrapped continuously, and also has drawbacks such as the fins 2 easily coming off.
The latter has the disadvantage that the fin removal process must be increased and the process becomes complicated, and both have the same disadvantage that the Z gold must be inserted and bent in the same way as in the conventional method.

The present invention has been made to improve these drawbacks, and as shown in FIG. 6, the long tube 1 is machined with uneven grooves in the portion O which will be bent in the subsequent bending process. , then fins 1 are continuously applied to the surface of the tube including the grooves.
This is a fin-wound heat exchanger made by winding a fin.

When forming spiral grooves 8 on the tube surface, forming the winding fins 2 and the grooves 8 so as to intersect with each other as shown in the enlarged view of FIG. It has the advantage that falling down can be prevented and the fins 2 can be wrapped very smoothly. In order to bend the fin-wrapped heat exchanger with the grooves 2 formed on the surface of the tube as shown in FIG. By winding the wound tube body, it is possible to bend the tube body 1 very easily without crushing it with a force so small that it is possible even by manual processing. This is because when the bent portion 3 is bent, the groove portion of the bent portion 3 is simply stretched without any change in wall thickness, so the outside of the bent portion is not crushed. On the other hand, the inner side of the bent portion easily contracts due to the effect of the machined grooves 8, and the stress is uniformly deformed because it is dispersed in each groove, so there is no local collapse as in the conventional case. The grooves on the surface of the tube body 1 are stretched and bent, and the cross-sectional shape does not change as in the conventional case, so the fins 2 bonded to the outer circumference of the tube body 1 do not come off as shown in Figures P and 8. In addition, since bending can be done with a small amount of force, the fins can be bent just by lightly supporting the inside of the fins, and the inner fins do not collapse and the outer fins remain regularly arranged at equal pitches, making it possible for this bent part to be used for sufficient heat exchange. Yes, the ability to improve heat exchange performance
can get. As mentioned above, in this embodiment, the tube body 1 of the finned heat exchanger, which is thinner than the conventional method, can be bent without crushing it, and the fins 2 can be bent without deforming. It can be bent in a short time and has excellent mass productivity, and it also allows for small bends that were previously considered difficult, making it extremely easy to produce high-performance heat exchangers and at a low cost.

For example, it becomes possible to easily manufacture a heat exchanger as shown in Fig. 1Jj, 9. In the figure, 1 indicates a grooved tube body, 2 indicates a fin, and 3 indicates a bent portion. Figure 10 and 1
Figure 1 shows an example of a method for forming grooves on a tube body 1.
A spiral groove 8 is formed by rotating three forming rolls 4, 5, and 6 arranged at a constant angle around the tube 7 and sinking them into the surface of the tube 7. Although the spiral grooves have been described above, it is clear that the present invention is not limited to this, and parallel independent grooves may be provided. According to the present invention as described above, the fins are present not only in the straight portions of the tube body but also in the bent portions, and the tube body can be bent without crushing the tube body and fins. It is possible to perform heat exchange and improve the overall heat exchange performance, and the fins are continuously wound spirally around the outer periphery of the tube including the groove without using a connecting tube such as a U pent tube. This makes it possible to easily bend the tube, which increases productivity and makes it suitable for mass production.Furthermore, by forming uneven grooves only in the part of the tube that is used for bending, the overall Not only can the fluid resistance be kept low, but the straight part of the pipe body will not be bent carelessly during the bending process and the overall shape will not be damaged. An excellent heat exchanger with fins can be obtained.

[Brief explanation of the drawing]

FIG. 1a is a schematic view showing the collapse phenomenon of a tube body that occurs when a conventional smooth tube is bent, and FIG. 1b is a sectional view taken along the line A-A of the collapsed portion. FIG. 2 is an external view showing a bent state of a smooth tubular body with fins wound around its surface. Figure 3 is an external view of a conventional heat exchanger in which the fins are not wrapped around the bent portion to make it easier to bend, Figure 4 is a schematic diagram of the heat exchanger shown in Figures W & 3 when bent. Fig. 5 is a schematic diagram of a heat exchanger with only the fins at the bent part removed; Fig. 6 is an external view of the tube in which grooves are formed only at the bent part in the first step of the present invention;
The figure is an enlarged view of the grooved part q of the heat exchanger shown in FIG. 6, in which fins are wrapped around the tube body, and FIG. 8 is an external view of the bent part of the heat exchanger shown in FIG. 7. FIG. 9 is an embodiment of the heat exchanger unit of the present invention, FIG. 10 is a schematic perspective view showing a groove machining method, and FIG. 11 is a sectional view taken along the line B--B in FIG. 10. 1 is a tube body, 2 is a fin, and 3 is a bent part.

Claims (1)

[Claims] 1. After forming an uneven groove only in the portion of the long tube that is to be bent, and then continuously winding fins in a spiral shape around the entire outer periphery of the tube, including the groove, A method for manufacturing a heat exchanger with fins, which is formed by bending a fin-wrapped tube into a predetermined shape with grooves.