KR19980065028A - How to make a fin tube - Google Patents

Abstract

The present invention relates to a method for producing a fin tube for fusion welding pins while forming a spiral at a predetermined interval on the outer circumference of a cylindrical tube by using a high frequency welding method.

The present invention is a fin tube formed by fusing a fin (2) in a spiral shape at a predetermined interval on the outer circumference of a pipe-shaped tube (1) of a predetermined size made of a metal material, wherein the fin (2) has a thickness of 0.2 to 2 mm or less and a height of 15 mm or less. Conductor 4 of the high frequency welder, which is operated at 400 to 600 Hz while being sequentially pressurized at 3 to 5 kg / cm 2 on the outer circumference of the tube 1 which is made of a band-like material and rotated by the predetermined means. The outer circumference and the fin 2 of the tube 1 at a position 3 to 12 mm apart from the welding point 12 fused between the welding position 11, which is the outer circumference of the tube 1, and the bonding portion of the fin 2, respectively. ) To be in close contact with each other.

The present invention provides a welding method for continuously welding a thin plate of pin 2 of a thin strip to the outer periphery of a thin tube of pipe 1 in a spiral manner. It is an effective invention that can produce a heat exchanger pipe with high heat efficiency precisely and in large quantities.

Description

How to make a fin tube

The present invention relates to a method for producing a fin tube for fusion welding pins while forming a spiral at a predetermined interval on the outer circumference of a cylindrical tube by using a high frequency welding method.

The hollow tube (pipe) is used for various purposes according to its diameter, and the present invention relates to a manufacturing method of closely welding a plurality of fins, such as fins, on the outer circumference of a small diameter tube. For example, it can be used as a heat exchanger pipe.

Pipes used in heat exchangers generally use a lot of steel due to their material cost. Depending on the application, stainless steel or copper pipes with high thermal conductivity may be used to obtain high durability. Absorption or release of the calories corresponding to the temperature difference between the hot or cold circulating material (liquid or gas) and the outside air circulated therein in the outside air, in accordance with the thermal conductivity of the pipe forming the inner and outer boundaries Although there are many differences in efficiency, the decisive factor in efficiency improvement is the surface area of the pipe, the area of contact between the pipe and the atmosphere. The same applies to the case where the heating wire is built into the pipe for the heater, but for the convenience of description, the following description will be given as an example of the case where the fin tube of the present invention and a pipe for a similar use are used in a heat exchanger.

Therefore, in order to improve the heat exchange rate mentioned above, the use of the heat exchanger pipe only as the tube 1 has been attempted to attach the helical fin 2 to the outer periphery of the tube 1 in some cases. The pin 2 wound around is narrow in its spacing, so that the tip of the welder does not enter and the thickness of the pin 2 is thin. Therefore, there is a problem in the overall welding between the tube 1 and the pin 2, It was only possible to roll the pin (2) of spirally (working on the lathe) and use only the starting and ending points by spot welding the outer periphery of the tube (1).

However, since the fin tube of the above-described structure is attached between the tube 1 and the fin 2 only at about two places, the heat capacity conducted to the outer periphery of the tube 1 in the tube 1 is increased by the tube 1 and the fin ( 2) there is a limit in improving the thermal efficiency because the gap is interposed between the convection, and the temporary bonded pin (2) is easily dropped from the tube (1) by a small impact, so that the durability is also extremely inferior.

The present invention has been made to propose a method for producing an efficient fin tube by smoothly solving the above problems, the pipe-type tube should be used in the thin plate heat exchange rate is high, but the butt welding (but welding) on the plate Using a high frequency welding method with excellent surface welding ability, the narrow fins 2 are wound around the outer periphery of the tube 1 while being welded at the same time so that they can be welded at the same time. Is as follows.

1 is a configuration diagram of a product according to the present invention,

Figure 2 is a schematic diagram of the production process of the present invention.

Explanation of symbols on the main parts of the drawings

1 --- tube

11 --- welding position 12 --- welding point

2 --- pin

3 --- pressure roll

31 --- groove

4 --- conductor

41 --- Electric Wire

1 is a configuration diagram of a product produced by the manufacturing method of the present invention, Figure 2 is a schematic diagram showing a process of using the manufacturing method of the present invention.

The present invention is a fin tube formed by fusing a fin (2) in a spiral shape at a predetermined interval on the outer circumference of a pipe-shaped tube (1) of a predetermined size made of a metal material, wherein the fin (2) has a thickness of 0.2 to 2 mm or less and a height of 15 mm or less. Conductor 4 of the high frequency welder, which is operated at 400 to 600 Hz while being sequentially pressurized at 3 to 5 kg / cm 2 on the outer circumference of the tube 1 which is made of a band-like material and rotated by the predetermined means. The outer circumference and the fin 2 of the tube 1 at a position 3 to 12 mm apart from the welding point 12 fused between the welding position 11, which is the outer circumference of the tube 1, and the bonding portion of the fin 2, respectively. Each of them is in close contact with each other.

In the above, it is preferable that the pin 2 is pressed at 3.5 to 4 kg / cm 2.

In the above, it is more preferable that the high frequency welding machine is welded at a welding speed of 10 to 30 m / min under an output of 40 to 150 kW while operating at 450 to 500 kW.

In the above, the conduits 4 which are in close contact with the outer circumference of the tube 1 and the fins 2 respectively form 4 to 10 mm with the conduit 4 on the pin 2 side while forming a V with the welding point 12. It is more preferable that it is spaced apart and it is made to energize with the conduit 4 of the tube 1 side 5-9 mm apart.

The method of the present invention configured as described above can be mass-produced according to the specifications of the tube 1 and the pin 2 made of pipes, which are easy to automatize.

Example 1

For example, in the case of spiral welding a pin 2 having a thickness of 0.4 mm and a height of 8 mm to the outer circumference of a steel tube 1 having a diameter of 15 Φ, for example, the output of an ultrasonic welding machine (not shown) is set to 50 kV and is pressed at a frequency of 450 kPa. The roll 3 was pressurized at 4 kg / cm 2 and welded at a speed of 25 m per minute. At this time, the connector 4 was installed 9 mm apart from the welding point 12 to the 8 mm pin 2 side to the tube 1 side.

Specimens 1.5m in length of the welded tube (1) were visually inspected, and the longitudinal cuts were made every 100 mm, and visual and fracture inspections at the shear plane were performed in Table 1, respectively.

TABLE 1

Example Material Welding voltage Frequency Press force (㎏ / ㎠) Welding speed (m / min) Congestion evaluation Visual inspection Cutting inspection Breaking test One Cast Iron Tube + Cast Iron Pin 50 450 4 25 T8F9 Good Good Good 2 Cast Iron Tube + Cast Iron Pin 100 400 3 20 T5F5 Good usually usually 3 Cast Iron Tube + Cast Iron Pin 150 600 5 30 T12F13 usually usually Good 4 Cast Iron Tube + Stainless Steel Pin 50 460 4 20 T7F7 Good Good Good 5 Cast Iron Tube + Stainless Steel Pin 100 400 3 18 T4F4 usually usually Good 6 Cast Iron Tube + Stainless Steel Pin 150 600 5 35 T12F12 usually Good Good 7 Stainless Steel Tube + Stainless Steel Pin 50 470 3.5 16 T6F7 Good Good Good 8 Stainless Steel Tube + Stainless Steel Pin 100 400 3 13 T3F3 usually usually usually 9 Stainless Steel Tube + Stainless Steel Pin 150 600 5 20 T11F12 Good usually usually 10 Stainless Steel Tube + Copper Pin 50 470 3.5 14 T6F5 Good Good Good 11 Stainless Steel Tube + Copper Pin 100 400 3 10 T3F3 usually usually Good 12 Stainless Steel Tube + Copper Pin 150 600 5 20 T11F11 usually Good usually

EXAMPLES 2-12

Each of the materials shown in Table 1 was taken, and the specimens were prepared in the same manner as in Example 1 under the conditions of Table 1, and the results were shown in Table 1 by the same method.

The evaluation is good when there is no fusion of the circumference of the weld before the visual inspection, and it is usually when the fusion is not more than 3 places or the weld bead is thicker than the pin thickness. Or when the weld bead is more than twice the thickness of the pin was determined to be bad, all of the above examples were recorded above the ordinary, there was no fusion defect.

In addition, the cut surface inspection judged that the depth of the nugget was greater than the pin thickness at the cut portion, that the thickness was less than the pin thickness, and that the nugget was not formed normally, and the fracture inspection was performed by pulling the pin 2 vertically. It was judged that the welded part or the pin was broken, and if the remaining pin 2 was broken more than twice as good as the pin thickness, it was determined to be good if the remaining pin 2 was less than 2 times.

As described above, within the technical scope of the present invention, although there are some errors in the skill of the work, specimens obtained by fusion than normal under all conditions were obtained.

In the present invention, the edges of the thin plate-like pins 2 are spirally welded to the outer periphery of the tube-like tube 1, and both the tubes 1 and the pins 2 are thin plate materials, and thus are not possible by general welding. Therefore, the intended purpose can be achieved only by a high frequency welding method in which heat is applied only to the surface. To this end, according to claim 1 of the present invention, a predetermined material of 400 to 600 kPa is applied under a pressing force of 3 to 5 kg / cm 2. The welder 4 was welded by a high frequency welder, and the conduit 4 was formed in a V-shape from the welding point 12 and is in close contact with the tube 1 and the fin 2 by 3 to 12 mm. As a means for pressing the pin 2 to 3 to 5 kg / cm 2 toward the tube 1 side, for example, as shown in FIG. 2, the pressure roll is positioned at a position spaced apart by the height of the pin 2 from the tube 1. (3) is provided so that the pin (2) is pressed against the surface of the tube (1) by applying a predetermined pressure to the pressure roll (3), in this case the pin (2) in the center of the pressure roll (3) It is preferable to form the groove 31 so that one end of the groove is inserted. In particular, in the high frequency welding method, since the heat of resistance is generated on the pressure roll 3 side due to the high vibration of the current, the pressure roll 3 made of steel or stainless steel is In the case of use, it is possible to improve durability by coating the surface with a high-resistance heat-resistant material with a predetermined thickness, for example, ceramic.

In addition, when the pin 2 is pressurized by the pressing roll 3 and becomes a thin plate of the pin 2 to be supplied, and the pins 2 ½ to ¾ are divided outward in the width direction for every predetermined length, the outer periphery of the tube 1 and The contacting area forms a closed curve in a spiral shape and the opposite side can produce a serrated type fin tube in which a crack is further opened. This increases the surface area of the sawtooth-shaped fin 2 to further improve heat exchange efficiency. It is apparent that even such a structure can be manufactured as it is by the manufacturing method of the present invention, and thus included in the scope of the present invention.

In addition, in claim 3 of the present invention, the output of the high frequency welding machine is limited to 40 to 50 kW, but the output can be welded out of the range limited to being proportional to the welding speed, but it is difficult to adjust the speed, so that a general welding technician handles it. The output is limited to the above range to have a speed that is easy to do.

If the pressing force is 5 kg / cm 2 or more, the pin 2 is squeezed into the outer periphery of the tube 1 to form a bead, and if the pressing force is 3 kg / cm 2 or less, the edge of the pin 2 is the tube (1). ), Welding defect (caused to be spaced apart part without welding) occurs, and the frequency of the high frequency welding machine is proportional to the conduction ratio of the welding base material and the pin. Is so deep that the shell of the tube 1 can be perforated, and under 400㎑, the nugget does not occur and the pin 2 falls off from the tube 1, and the welding spot becomes a heating area. If the distance between the conductors (12) and the conductors (4) is 12 mm or more, an excessive fusion of 3 mm or less will cause welding beads to be excessively formed and perforated.

As described above, the present invention provides a welding method for continuously welding a thin plate of pin 2 of a thin strip to the outer periphery of a tube 1 on a thin pipe. It is an effective invention that enables to realize the precise and mass production of heat efficient pipes for heat exchangers.

Claims (4)

A fin tube formed by fusing the fins 2 in the form of spirals of a predetermined interval on the outer circumference of a pipe-shaped tube 1 of a predetermined standard made of metal, wherein the fins 2 are made of a strip material having a thickness of 0.2 mm to 2 mm and 15 mm or less. Pressurized to 3 to 5 kg / cm 2 in sequence on the outer periphery of the tube 1 which is rotated by the rotating means by a predetermined pressing means, and the tube 4 of the high frequency welder which is operated at 400 to 600 Hz is On the outer circumference and the fin 2 of the tube 1, which are 3 to 12 mm apart from the welding point 12 fused between the welding position 11, which is the outer circumference of (1), and the bonding portion of the fin 2, respectively. Method for producing a fin tube, characterized in that the close contact is energized. The method of manufacturing a fin tube according to claim 1, wherein the fin (2) is pressed at 3.5 to 4 kg / cm 2. The method of manufacturing a finned tube according to claim 1, wherein the high frequency welder is welded at a welding speed of 10 to 30 m / min under an output of 40 to 150 kW while operating at 450 to 500 kW. 4. The connector according to any one of claims 1 to 3, wherein the conductors 4, which are in close contact with the outer circumference of the tube 1 and the fins 2, respectively, form a V with the welding point 12. (4) A method of manufacturing a fin tube, characterized in that it is spaced 4 to 10 mm apart from each other and 5 to 9 mm apart from the connector (4) on the tube (1) side.