JPS6369175A - Manufacture of heater unit - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a heater unit in which a cord-shaped heating element is arranged in a meandering manner for use in a heating panel or a defrosting heater for a refrigerator/freezer.

Conventional technology Conventionally, this type of heater unit was manufactured by Japanese Patent Publication No. 49-7534.
This method is disclosed in Japanese Utility Model Publication No. 60-178991.

That is, according to Japanese Patent Publication No. 49-7534.

A cord-shaped heating element with a thermoplastic resin layer applied to the outermost layer of the heating element coated with a non-softening insulator is pressed and heated onto a thin metal plate, and the thermoplastic resin layer is melted and bonded to the thin metal plate. Ta.

Further, according to Japanese Utility Model Application Publication No. 60-178991, a metal body is coated on an insulating outer covering layer of a cord-shaped heating element.

This metal body was coated with a thermoplastic jacket having a melting point lower than that of the insulating jacket, and then this thermoplastic jacket was heat-welded to the planar body.

Problems to be Solved by the Invention However, conventional heater units have the following drawbacks.

That is, in Japanese Patent Publication No. 49-7534, since the contact surface between the cord-shaped heating element and the thin metal plate is less than 20%, the efficiency of heat transfer to the thin metal plate is poor.

Since the cord-shaped heating element and the thin metal plate are joined by welding a thin adhesive and a thermoplastic resin layer in a small area, if one localized overheating occurs, the cord-shaped heating element may come off from the metal thin plate or it may be used for a long time. The disadvantages are that the reliability of adhesion is poor when bonding, and that it is expensive because it uses a non-softening insulator such as silicone rubber.

In addition, in Japanese Utility Model Application Publication No. 60-178991, since the cord-shaped heating element and the planar body are joined using a thermoplastic jacket and there are few joint surfaces, they may come off when abnormal overheating occurs or may occur for a long period of time. The adhesive reliability during use is poor, and since the metal body is covered, the metal body wrapped around the bent part of the cord-shaped heating element may become embedded in the insulation layer, reducing the dielectric strength voltage, or the bending resistance may be poor. There are drawbacks such as reduced workability during meandering wiring and increased cost due to the complicated structure of the cord-shaped heating element.

Means for Solving the Problems The present invention has been made to eliminate the above-mentioned drawbacks.2 A method for manufacturing a heater unit according to the present invention is as follows.

The first step is to meander the cord-shaped heating element provided with the heat-fusible coating layer on the outermost layer, and to place the heat-fusible layer provided on the surface of the soft metal sheet toward the cord-shaped heating element. The second step is to weld the coating layer and the heat-adhesive layer by thermocompression bonding, and the third step is to press-form the thin metal sheet through the elastic body from the thin metal sheet side so that the thin metal sheet encloses the cord-shaped heating element and is in close contact with the thin metal sheet. Consists of processes.

Effect By forming a heater unit through the manufacturing process as described above, heat diffusion from the cord-shaped heating element to the thin metal plate is greatly improved, and temperature distribution can be made uniform. Further, since the metal thin plate mechanically holds the cord-shaped heating element, there is no problem of the cord-shaped heating element coming off and causing local overheating, and the durability and reliability are excellent.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows nine heater units of the present invention.
After winding the heating wire 6 in a spiral around the outer circumference of the core thread 2, the outermost layer is made of heat-fusible vinyl chloride having insulation properties,
A cord-shaped heating element 5 is composed of a coating layer 4 made of a thermoplastic elastomer or the like stewed by extrusion molding, and 5 is [103
A thin metal plate such as aluminum foil having a thickness of ~0.2+w+ and having good thermal conductivity, 6 is a material that is laminated in advance on the surface of the thin metal plate 5 by lamination processing and can be welded to the coating layer 4, such as vinyl chloride or vinyl acetate. , polyolefin, etc., and has a thickness of cL01 to 0.1 ms+. A first step of arranging the cord-shaped heating element 1 in a meandering manner, placing the metal thin plate 5 so that its heat-sealing layer 6 faces the cord-shaped heating element 1 side, and heating it at a temperature of 120 to 250° C. a second step of welding the covering layer 4 and the heat sealing layer 6 by applying pressure for seconds;
By interposing an elastic material, for example, a sheet of rubber foamed 5 to 20 times larger, on the thin metal plate 5 side, and applying pressure at a pressure of 50 to 300 M, the thin metal plate 5 is formed and encloses the cord-shaped heating element 1. and a third step of bringing them into close contact.

FIG. 2 shows another structural example of the cord-shaped heating element 1 used in the present invention. 2 is a core thread made of fibers such as polyester or glass; 6 is copper wrapped around the outer circumference of the core thread 2;
A heating wire such as nichrome, 7 is an insulating layer such as vinyl chloride or silicone rubber formed by extrusion molding around the outer periphery of these, and 4 is a polyolefin, polyester, thermoplastic elastomer, etc. formed by extrusion molding around the outer periphery of the insulating layer 7. It is a heat-fusible coating layer consisting of.

By providing the thermally adhesive coating layer 4 around the outer periphery of the insulating layer 7, the welding in the second step becomes more reliable, and the contact area with the thin metal plate 5 can be increased, thereby improving the efficiency of heat diffusion. can be done.

FIG. 6 shows a planar heating element based on the heater unit shown in FIG. 1, and 8 is a metal plate or synthetic resin member that is bonded to the thin metal plate 5 by melting the heat-sealing layer 6 by thermocompression bonding. The thin metal plate 5 is press-formed before being joined to the base material 8, and is tightly enclosed around the outer periphery of the cord-shaped heating element 1.

Next, the operation of this embodiment having the above configuration will be explained.

FIG. 4 shows the temperature distribution characteristics on the surface of the heater unit of an embodiment of the present invention and a conventional example.

The heater units of the embodiment and the conventional example have the component configurations shown in Table 1-1. This example includes a first step of arranging the cord-shaped heating elements 1 in a meandering manner so that the arrangement pitch is 30 wam, and a second step of welding the cord-shaped heating elements 1 and the thin metal plate 5 by thermocompression bonding at 180° C. for 2 seconds. 2 steps and 200
A heater unit is obtained from the third step in which the thin metal plate 5 is brought into intimate contact with the surface of the cord-shaped heating element 10 under a pressure of 100%.

On the other hand, in the conventional example, the pitch of the cord-shaped heating elements is 30rm.
After arranging them in a meandering manner, the cord-shaped heating element and the thin metal plate were welded together by thermocompression bonding at 200° C. for 2 seconds to obtain a heater unit. In the conventional example, the temperature difference between the surface of the cord-shaped heating element and the surface of the aluminum foil between the pitches was about 20°C, whereas in the present embodiment, the temperature difference was about 9°C, and the temperature distribution was uniform. In addition, the maximum temperature of the surface temperature of the cord-shaped heating element 1 can be lowered in this embodiment due to better thermal diffusion than in the conventional example, so that it is less susceptible to thermal aging when used for a long period of time.

The cord-shaped heating element 1 becomes difficult to come off from the aluminum foil, and durability and reliability can be improved.

Table-1 The cord-shaped heating element 1 and the thin metal plate 5 have a thermally adhesive coating layer 4.
and the heat-adhesive layer 6 are welded together, and the thin metal plate 5 is formed into a structure in which the outer periphery of the cord-shaped heating element 1 is enclosed and tightly adhered, so that the heat generated from the cord-shaped heating element 1 is efficiently absorbed. Since it can be diffused into the thin metal plate 5, the temperature distribution of the thin metal plate 5 can be made uniform. Further, since the thin metal plate 5 mechanically includes and fixes the cord-shaped heating element 1, the cord-shaped heating element 1 does not come off from the thin metal plate 5, so there is no inconvenience that two localized overheatings occur.

Excellent durability and reliability when used for long periods of time.

The cord-shaped heating element 1 used in the present invention has an outer diameter in the range of 1.8 to 3.0 mm because it is easy to arrange in a meandering manner in the first step and it is easy to be wrapped and tightly attached by the thin metal plate 5 in the third step. The outermost heat-sealing layer 4 preferably has a rubber hardness of 50 to 120. The reason why the hardness of the material of the coating layer 4 is limited is as follows.

That is, if the hardness of the coating layer 4 exceeds 120 in terms of rubber hardness, the pressing force will be concentrated when the thin metal plate 5 is pressure-formed in the third step, and the aluminum foil will break.

If the hardness is less than 50, the deformation of the coating layer 4 will be too large, making it difficult to pressure-form the aluminum foil.

Therefore, the hardness of the coating layer 4 is suitably 50 to 120 in terms of rubber hardness, and more preferably 60 to 100. Also,
The material of the covering layer 4 is one that has both insulation and welding properties.
For example, a tubing made of a thermoplastic nidistomer made of ethylene propylene resin and ethylene propylene rubber, or polyethylene on which an insulating layer 7 such as vinyl chloride is provided.

A structure having a heat-fusible covering layer 4 made of a material such as vinyl acetate or a thermoplastic nidistomer is suitable.

Next, the heat-adhesive layer 6, which has the function of fixing the cord-shaped heating element 1 and the thin metal plate 5, is required to have the property of being melted and welded to the covering layer 4 during the thermocompression bonding in the second step. For example, if the covering layer 4 is a vinyl chloride-based material, the heat-adhesive layer 6 is made of a vinyl chloride-based material or a polyester-based material, and if the covering layer 4 is an olefin-based thermoplastic nitrogen, the heat-adhesive layer 6 is made of polyethylene.

Materials such as polyboropyrene and vinyl acetate are suitable. Further, when it is necessary to bond the base material 8 such as a metal plate or synthetic resin again by heat-pressing, a resin component containing polyester, olefin, etc. having a crystalline resin component is suitable. Furthermore, the thickness of the thermal adhesive layer 6 is 0.01 to a1 m.
By doing so, the bonding strength between the thin metal plate 5 and the base material 8 can be ensured.

The thin metal plate 5 is made of soft aluminum foil with a thickness of 003 to Q, 2 mm, since it is necessary to cover and adhere the cord-shaped heating element 1 by 50 to 300% pressure forming in the third step.
Good. Here, the reason for limiting the thickness is as follows. If the thickness is less than 0.03, it is not preferable because it becomes easy to break during pressure molding and the heat diffusion properties deteriorate. Further, if the thickness becomes thicker in order of 0.2, it becomes difficult to pressure mold and the enclosing and adhesion is not achieved, which is not preferable. Therefore.

The thickness of the thin metal plate 5 is suitably 0.03 to α2, more preferably 0.05 to cL1WrIR.

When the thin metal plate 5 is tightly attached to the surface of the cord-shaped heating element 1 in the third step, when pressure molding is performed while heating, the coating layer 4
Alternatively, the insulating layer 7 may undergo thermal deformation.

Since dielectric strength cannot be ensured, the material must be deformed under pressure at a temperature that does not easily cause thermal deformation. The pressure applied to the thin metal plate 5 through the elastic body varies depending on the thickness and hardness of the cord-shaped heating element 1 and the thickness of the thin metal plate 5, but is between 50 and 300.
The optimum value can be selected within the product range. The thin metal plate 5 is pressure-formed by making the cord-shaped heating element 1 side a hard surface and applying pressure to the metal thin plate 5 side through an elastic body, so that the metal thin plate 5 is molded onto the outer peripheral surface of the cord-shaped heating element 1. This is to allow the molding to be performed while stretching along the length. The elastic body used at this time has a foaming rate of 5
~20x rubber is suitable.

゛Again. When joining the thin metal plate 5 and the base material 8 by thermocompression bonding again, the heater unit may be placed in a jig that does not apply significant pressure to the cord-shaped heating element 1.

Effects of the Invention According to the present invention, the first step of meanderingly arranging the cord-shaped heating element provided with the heat-fusible coating layer on the outermost layer, and the heat-fusible layer provided on the surface of the thin metal plate. The second step is to place the metal sheet facing toward the cord-shaped heating element and weld it by thermocompression bonding, and the second step is to mold the thin metal sheet by applying pressure from the thin metal sheet side through an elastic body so as to tightly fit it to the surface of the cord-shaped heating element. By manufacturing the heater unit through three steps, the following effects can be obtained.

(1) Heat diffusion from the cord-shaped heating element to the thin metal plate is improved, and temperature distribution is made uniform.

(2) Since the thin metal plate mechanically holds the cord-shaped heating element, the cord-shaped heating element does not come off and cause local heat generation, and durability and reliability are improved.

(8) Since the cord-shaped heating element structurally does not cause a drop in dielectric strength or flexibility, it has good wiring properties when manufacturing the heater unit, and can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a planar heating element as a heater unit showing an embodiment of the present invention, and FIG. 4 is a temperature distribution characteristic diagram on the surface of the heater unit of the embodiment and a conventional example. 1... Cord-shaped heating element. 4...Covering layer. 5...Thin metal plate. 6... Heat fusion layer.

Claims (1)

[Claims] A first step of meanderingly disposing a cord-shaped heating element (1) having a heat-fusible coating layer (4) on the outermost layer, and a thin metal plate (5).
The heat-sealing layer (6) provided on the surface of the cord-shaped heating element (
1) a second step of welding the coating layer (4) and the heat-sealing layer (6) by thermocompression bonding by placing the thin metal plate (5) facing toward the side;
A method for manufacturing a heater unit, comprising a third step of press-forming the cord-shaped heating element (1) from the thin metal plate (5) side through an elastic body so as to enclose and closely fit the cord-shaped heating element (1).