JPH0120923B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing a finch tube using high-frequency resistance welding, and more specifically, the present invention relates to an improvement in a method for manufacturing a finch tube using high-frequency resistance welding. When inserting a tube into this spiral fin material and welding the fin material and the tube, a cylindrical insulator is inserted between the unwelded part of the tube and the fin material so that the current is concentrated at the welded part. The present invention relates to a method for manufacturing a finch tube characterized by having a body interposed therein.

Conventionally, Japanese Patent Publication No. 45-13701 is known as a method for manufacturing welded finch tubes, and the feature of this invention is that an alternating current of about 1 MC to 10 MC is used,
The purpose is to weld the fin material and tube.

According to this method, a finch tube having a significantly thinner wall thickness than a finch tube obtained by a rolling method or a general welding manufacturing method including the use of high frequency current can be manufactured reliably and at a high speed.

Here, the thin wall thickness of the fins leads to an improvement in the heat exchange rate and also reduces the cost of raw materials, so it has a very large technical and economical advantage. To explain the outline of the invention with reference to FIG. 1, the fin material 1 is rolled up and supplied by the rotation of the tube 2 in the direction of arrow A and the advancement in the direction of arrow B, and at the same time as it is wound, the fin material 1 is A first electrode 31 in contact with the tube 2 and a second electrode 32 in contact with the tube 2
By passing an alternating current of, for example, about 1 MC to 10 MC between them, the fin material 1 and the tube 2 are welded, and a fin tube having spiral fins is successively manufactured. Here, the fin material 1 is supplied in the form of an elongated strip until just before welding, and is wound around the tube 2 to sequentially form a spiral shape.

However, when welding the fin material to the tube while winding it in a spiral shape in this way, the smaller the diameter of the tube, the smaller the curvature of the fin. There may be wrinkles on the skin. This becomes more noticeable as the thickness of the fin becomes thinner.

These wrinkles cause defects in heat transfer performance, pressure loss, dust adhesion, etc. when the product is manufactured, and also reduce the contact area of the fin material with the tube, making welding unstable and reducing strength. This can also be the reason why you don't get enough.

In order to avoid this, a manufacturing method uses a fin material that is formed into a spiral shape in advance, inserts a tube into this spiral metal plate, and welds the fin material and tube while rotating. was devised.

However, in this method of inserting tubes into a spiral fin material and sequentially welding them to the tubes, current flows to contact areas other than the areas to be welded, and the welding current is concentrated on the target area. Not only is this not possible, but there are also problems such as abnormal sparks occurring at the contact portion.

The present invention was devised in view of the above problems, and involves inserting a tube in the axial direction into a fin material that has been formed into a spiral shape in advance, and welding the fin material and the tube using a high frequency resistance welding method. A cylindrical electrical insulator is interposed between the unwelded parts of the fin material and the tube, and the electrical insulators are sequentially removed as the welded parts are reached, and the fin material and the tube are brought into contact only at the welded parts. The purpose of the present invention is to provide a method for manufacturing a finch tube that can produce a finch tube of excellent quality by concentrating current on the welded part.

Examples of the present manufacturing method will be described in detail below with reference to the drawings.

FIG. 2 is a schematic diagram for explaining an embodiment that is an improvement over the conventional example. The fin material 1' is previously formed into a spiral shape. In this case, as a processing method for forming the fin material into a spiral shape without causing wrinkles, for example, natural curling force due to taper rolling of a roller can be considered.

The tube 2 is inserted into this spiral fin material 1' from the axial direction. That is, the inner edge of the fin material 1' is brought into contact with the outer peripheral surface of the tube 2, and the tube 2 is rotated in the direction of arrow A and advanced in the direction of arrow B. At this time, the electrode 31 in contact with the fin material 1 and the electrode 32 in contact with the tube 2 are rotated in the direction of arrow A and moved forward in the direction of arrow B. Welding current is applied to the

As a result, the tube 2 and the fin material 1' are welded together, and as the tube 2 rotates and moves forward, the fin tubes are manufactured one after another.

Here, the second electrode 32 is fixed to an insulated fixed part near the welding part 6, and is configured to come into sliding contact with the outer peripheral surface of the tube 2 as the tube 2 rotates in the direction of arrow A and moves forward in the direction of arrow B. , the first electrode is similarly configured to come into sliding contact with the fin material 1', but a detailed description of its mechanism is omitted. Further, the mechanism for rotating and advancing the tube 2 is the same as a commonly used rotating mechanism, so its description is omitted.

However, in this method of sequentially welding the fin material 1' and the tube 2, it is necessary to weld not only the welded part 6 but also the unwelded parts where the fin material 1' and the tube 2 contact, such as X and Y. The current flows, and the current cannot be concentrated on the target welding part 6. Moreover, abnormal sparks may occur at the contact points X and Y, and improper welding may occur, resulting in many inconveniences in commercialization.

Therefore, the present invention prevents this abnormal spark,
Moreover, the unwelded portion of the tube 2 is electrically insulated so that the desired current is concentrated to the target portion. That is, as shown in FIG. 3, an electrical insulator 5 is interposed between the unwelded portion of the tube surface and the fin material 1'. A hollow tube made of ceramic, for example, is used as the electric insulator 5, and the tube 2 is inserted into the hollow, and the fin material 1' is inserted between the unwelded parts.
and tube 2 are electrically insulated.

Incidentally, as the tube 2 and the fin material 1' are welded, the electric insulator 5 is gradually attached to the tube 2.
The structure is such that it can be pulled out in the direction of arrow C, and the device for pulling it out is not shown.

As described above, according to the present invention, by interposing an electrical insulator between the fin material between the unwelded parts and the tube, the above-mentioned problems occur even if the fin material is formed into a spiral shape in advance. Moreover, the welded portions of the fins and tubes can be made uniform. That is, in the finch tube manufactured by the manufacturing method of the present invention, the heat exchange efficiency as designed is exhibited.

Further, according to the manufacturing method of the present invention, it is expected that the processing speed will be further improved compared to the conventional method of winding the fin material around the tube and welding it, so it can be said that the manufacturing method is excellent in mass production.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic diagrams illustrating a conventional method for manufacturing a finch tube, and FIG. 3 is a schematic diagram illustrating a method for manufacturing a finch tube according to the present invention. In the figure, 1 is a fin material, 1' is a spiral fin material,
2 is a tube, 31 is a first electrode, 32 is a second electrode, 4 is a power source, 5 is an electric insulator, and 6 is a welding part.

Claims (1)

[Claims] 1. When manufacturing a fin tube by welding a fin material previously formed into a spiral shape to a tube by high-frequency resistance welding, a cylindrical electrical insulator is interposed between the unwelded portion of the fin material and the tube. A method for producing a finch tube.