JP2753864B2 - Manufacturing method of sheet heating element - Google Patents

Description

The present invention relates to a method for producing a sheet heating element used as a general-purpose or industrial electric heat source.

[Prior Art] Conventionally, as a method for manufacturing this type of planar heating element, a metal foil is subjected to an etching treatment to produce a planar heating element.

In the method of manufacturing the sheet heating element, first, a plastic film is attached to one surface of a single metal foil such as stainless steel or a nickel-chromium alloy. A portion having a predetermined pattern is masked on the opposite surface of the metal foil by a photosensitive agent or silk printing. Next, the metal foil is immersed in a chemical reaction solution to perform an etching process.

According to the etching process, the metal foil portion other than the predetermined pattern reacts with the chemical reaction solution and is removed, so that the masked predetermined pattern portion remains. Thus, a planar heating element having a predetermined pattern is obtained.

[Problems to be Solved by the Invention] However, in the etching process, if the masking state of the predetermined pattern portion is not completely performed, pinholes may be generated in the predetermined pattern. If this pinhole is present, the resistance value varies in a predetermined pattern, and the sheet heating element becomes defective.

In addition, when the processing time of the etching process is not accurate or the chemical reaction liquid is dirty, the etching process cannot be completely performed on the sheet heating element. Therefore, the sheet heating element has a large variation in resistance value, and it is difficult to control the resistance value.

Furthermore, when mass-producing this planar heating element, it is expensive to manufacture an underprint, a printing machine, and the like.

In addition, since the metal foil is thin (about 5 to 100 μm), a predetermined pattern formed by the metal foil is easily bent during transportation, mounting to an installation target, and the like, and thus has a problem that it is difficult to handle.

Therefore, an object of the present invention is to provide a method of manufacturing a sheet heating element for obtaining a sheet heating element having a very small variation in resistance value and excellent mass productivity.

[Means for Solving the Problems] According to the present invention, in a method of manufacturing a planar heating element having a predetermined pattern, a plurality of metal foils larger than the outer diameter of the predetermined pattern are prepared. Laminating metal foils on each other to form a metal foil laminate, laminating plates on both sides of the metal foil laminate in the laminating direction, forming holes in the plate at portions excluding the predetermined pattern And inserting a fixing tool through the hole, sandwiching the metal foil between the plate members, and then cutting the plate member and the metal foil along the predetermined pattern by electric discharge machining. Thus, a method for manufacturing a planar heating element is obtained.

Further, according to the present invention, the predetermined pattern includes an inner heating pattern on a first virtual circle, an outer heating pattern on a second virtual circle outside the first virtual circle, and the outer heating pattern. A reinforcing pattern in which a part of the pattern is connected to a part of the inner heating pattern, and the cutting in the cutting step is performed along the inner heating pattern, the inner heating pattern, and the reinforcing pattern. Thus, a method for producing a heating element in the form of a plate is obtained.

Embodiment FIG. 1 shows a sheet heating element obtained by a method of manufacturing a sheet heating element according to an embodiment of the present invention, and FIGS. 2 to 4 show manufacturing steps of the sheet heating element. ing.

As shown in FIG. 1, the planar heating element has a plurality of strip-shaped predetermined patterns 1 extending in the same plane. The predetermined pattern 1 includes an inner heating pattern 1a on the first virtual circle and a pair of outer heating patterns 1b on the second virtual circle outside the first virtual circle. The inner heat generation pattern 1a is meandering and extends on the first virtual circle. The pair of outer heat generating patterns 1b meanders at different positions on the second virtual circle. Both ends of the inner heat generating pattern 1a are connected to one end of the pair of outer heat generating patterns 1b via the connection pattern 2, respectively. The electrode portions 3 are respectively connected to the other ends of the pair of outer heating patterns 1b. The reinforcing pattern 5 is connected to each of the opposing portions of the inner heat generating pattern 1a and the pair of outer heat generating patterns 1b.
These reinforcing patterns 5 are portions to be separated before mounting to the mounting object in order to make the temperature distribution of the heat generating patterns 1a and 1b uniform.

In the method of manufacturing the planar heating element, first, a metal foil 7 larger than the outer diameter of the predetermined pattern 1 shown in FIG. 1 is prepared. The metal foil 7 is made of a heat-resistant metal material such as stainless steel or a nickel-chromium alloy. The thickness of the metal foil 7 is about 5 to 100 μ.

Next, a plurality of metal foils 7 are laminated on each other to form a metal laminate 9. The thickness of the metal laminate 9 is about 1 to 10 mm.
The metal laminated body 9 has one plate on each side in the laminating direction.
Overlay 11 The plate 11 uses a metal plate.

Further, a plurality of holes 13 penetrating in the laminating direction are formed in the metal laminate 9 and the plate 11 as shown in FIG.
These holes 13 are located at portions other than the heat generation patterns 1a and 1b.

As shown in FIG. 4, a fixture 15 is inserted into each hole 13. The metal laminate 9 is sandwiched and fixed between the plate bodies 11 by these fixing members 15. As the fixture 15, for example, a bolt and a nut are used. The bolt is inserted through the hole 13 from one side of the plate 11 and a nut is screwed into a screw portion of the bolt protruding from the outer surface of the plate 11 on the opposite side. Can be pinched and fixed. Thereby, each of the metal foils 7 can be fixed while suppressing bending.

Thereafter, the plate 11 and the metal laminate 9 are cut along the heat generating patterns 1a and 1b. An electric discharge machine (not shown) is used for cutting. In the electric discharge machine, the shape of the sheet heating element is input in a program, and when the sheet is cut in accordance with the program, a plurality of heating patterns 1a and 1b can be simultaneously formed in a laminated state. At this time, the electrode portion 3 and the reinforcing pattern 5 are also formed at the same time. The fixtures 15 are removed from the holes 13 of the heat generating patterns 1a and 1b, and the plate 11 is removed, so that the heat generating patterns 1a and 1b can be used as sheet heat generating elements one by one.

The reinforcing pattern 5 reinforces the heat generating patterns 1a and 1b while being connected between a part of the outer heat generating pattern 1b and a part of the inner heat generating pattern 1a. Reinforcement pattern 5
Plays a role in preventing the heat generating patterns 1a and 1b from being bent and damaged during the secondary processing operation of transporting the sheet heating elements 1 one by one or mounting them on a mounting object such as a pot or a copying machine.

The plurality of sheet heating elements can be attached to a large attachment object by connecting a plurality of sheet heating elements to each other by spot welding or the like by the electrode portion 3.

[Effects of the Invention] As described above, according to the method for manufacturing a planar heating element of the present invention, a plurality of metal foils are laminated to form a metal laminate, sandwiched and fixed by a plate body, and then subjected to electrical discharge machining to produce a planar heating element. In order to form the body, processing is performed by suppressing the bending of the metal foil. In addition, since a plurality of metal foils can be processed at the same time, the metal foil can be omitted, and a method of manufacturing a sheet heating element excellent in mass productivity can be obtained.

In addition, since the sheet heating element is formed by electric discharge machining, a finished state is good, and a heating pattern with very small variation in resistance value can be obtained.

Further, since the heat generating portion reinforcing pattern prevents the heat generating pattern from being bent, handling of the planar heat generating element is facilitated.

[Brief description of the drawings]

FIG. 1 is a plan view of a sheet heating element manufactured by a method of manufacturing a sheet heating element according to an embodiment of the present invention, and FIGS. 2 to 4 show a method of manufacturing the sheet heating element of FIG. FIG. 2 is a perspective view showing a state in which a metal foil is laminated, FIG. 3 is a perspective view showing a state in which a plate is superimposed on a metal laminate, and FIG. 4 is a state in which the metal laminate and the plate are fixed. It is a perspective view of. 1; predetermined pattern, 1a; inner heating pattern, 1b; outer heating pattern, 3; electrode part, 5; reinforcing pattern, 7; metal foil, 9; metal laminate, 11; plate, 13;

Claims (2)

(57) [Claims] 1. A method for manufacturing a planar heating element having a predetermined pattern, comprising: preparing a plurality of metal foils having a larger outer diameter than the predetermined pattern; Making a laminate, laminating a plate on both sides in the laminating direction of the metal foil laminate, forming a hole in the plate at a portion excluding the predetermined pattern, and inserting a fixing tool into the hole A sheet heating element characterized by comprising a cutting step of cutting the plate and the metal foil along the predetermined pattern by electric discharge machining after sandwiching the metal foil between the plate bodies. Production method. 2. The method according to claim 1, wherein the predetermined pattern includes an inner heating pattern on a first virtual circle, an outer heating pattern on a second virtual circle outside the first virtual circle, and one of the outer heating patterns. 2. A reinforcing pattern having a portion connected to a part of the inner heat generating pattern, and the cutting in the cutting step is performed along the inner heat generating pattern, the inner heat generating pattern, and the reinforcing pattern. The method for producing a sheet heating element of the above.