JPH06290917A - Manufacture of flame-sprayed heater - Google Patents

Abstract

PURPOSE:To control the resistance value of a heater in an excellent reproducible and highly precise manner by a method wherein a groove, in the width of the heater and in depth larger than the thickness of the heater, is provided and after an insulative film and a heating film have been flame-sprayed in the groove, the unnecessary film is removed by polishing. CONSTITUTION:An aluminum plate 1, which is the base material, is coated with organic coating material leaving the pattern P of a heating film. Then, the above-mentioned coated aluminum plate 1 is uniformly corroded, and the groove 2 corresponding to the pattern P is etched. Then, the surface of the base material 1 is blasted by an alumina grid, a base film 10 of Ni+Cr alloy, an Al2O3 insulating film 11 and an Ni+Cr heating film 12 are plasma spray- coated successively. Then, the surface of the heating film is polished until the pattern P appears. As a result, the control of resistance value by the film thickness control of the heating film by several mum order can be made easier, and the manufacturing method for a flame-spray heater, with which the cost for the entire flame-spray process is cut down, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thermal spray heating element that produces heat when energized.

[0002]

2. Description of the Related Art The resistance value of an electric resistance heating element is the most important factor in design, and since this resistance value is inversely proportional to the cross-sectional area of the resistance element, even when manufacturing the heating element by thermal spraying,
It is very important to spray the film thickness and width as designed.

[0003]

Conventionally, masking has been used for thermal spraying to an arbitrary width (for example,
For example, a method for forming a surface heating film using an electric cooking appliance according to Japanese Utility Model Publication No. 58-120597 and natural sand iron according to Japanese Patent Publication No. 2-56425). However, with a coating sprayed to an arbitrary width by masking, the thickness of the mask itself may cause turbulent gas flow on the surface of the material to be sprayed, and local changes in spraying conditions due to the shape of the sprayed object. As a result, the deposition of thermal spray particles becomes non-uniform, which limits the control of the width of the film and especially the film thickness. In particular, the narrower the width of the film, the more difficult it becomes to control the film thickness.

Therefore, if the conventional masking is used, it becomes difficult to make the resistance value of the film constant. In addition, the mask material is limited to heat-resistant and rigid materials, so there is a material cost when it is thrown away, and a processing cost for peeling off the adhered film when it is reused, which increases the cost of the entire thermal spraying process. Cause

The present invention is several μm, which is difficult in the prior art.
It is an object of the present invention to provide a method for manufacturing a thermal spray heating element that facilitates the management of the resistance value by controlling the thickness of the heating element coating on the order and reduces the cost required for the overall thermal spray processing.

[0006]

The manufacturing method according to the present invention comprises:
A groove having an arbitrary depth and an arbitrary width is previously engraved on the surface of the conductive base material, and the conductive material is sprayed on the groove, and then the coating surface of the sprayed conductive material is polished. It is characterized in that the film is left only inside the groove and the resistor is formed on the base material by a conductive film whose film thickness is arbitrarily determined.

The difference in the coefficient of thermal expansion between the base material and each layer of the thermal spray heating element can be prevented from peeling by forming a graded composition between the layers.

[0008]

In the method for producing a thermal spray heating element of the present invention, when the base material is conductive, the width of the heating element is several tens of percent larger than the thickness of the heating element (this depth depends on the use of the product). (Decision) Engrave a groove by cutting, etching, laser, electric discharge, etc., and in this groove, a base film (if necessary), an insulator film,
The heating element coating is sprayed in this order until the heating element coating reaches the designed thickness or more, and then unnecessary coating is removed by polishing to control the heating element coating in units of several μm and to reduce the resistance value. Manage with high reproducibility and high accuracy. Further, when the heat is generated, the heat dissipation is small because the layer is inside the substrate. If necessary, an insulating film is sprayed on the heating element film or is processed by Teflon or the like.

When the surface of the base material is an insulator, the engraved groove is sprayed with a conductive material until it is filled with the conductive material, and then the unnecessary film other than the groove is removed by polishing. .

By these processes, it becomes easy to control the resistance value and the accuracy is improved. Moreover, since it does not depend on the mask, the cost is reduced.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, an aluminum-based plate 1, which is a base material, is coated with an organic paint (not shown) while leaving the pattern P of the heating element film. Next, the aluminum plate 1 coated with this paint is uniformly corroded in hydrochloric acid, and the groove 2 corresponding to the pattern P is etched to a depth of about 200 μm, for example.

Next, the surface of the base material 1 is blasted with an alumina grid, for example, an undercoat 10 of Ni + Cr alloy having a thickness of 50 μm, for example, Al ₂ O _{3 having a} thickness of 300 μm.
Insulator film 11 and Ni + C having a thickness of 200 μm, for example
The heating element coating 12 of r is sequentially plasma sprayed.

Finally, the surface is polished to form the heating element film 12
The pattern P is completely revealed, that is, the thickness t is polished in FIG. In this state, the pattern P of the heating element film 12 is held in the insulator film 11.

Terminals 13 and 1 are provided on both ends of the heating element film 12.
4 was attached, and the resistance value between both terminals 13 and 14 was measured by the resistor 15. As a result, fluctuations in the resistance value of the ten substrates 1 were obtained with high accuracy of plus or minus 5%.

FIGS. 3 to 5 show another embodiment of the thermal spray heating element obtained according to the present invention. This heating element has, for example, a groove 4 having a depth of 0.3 mm and a width of 10 mm in a stainless steel tube 3 having an outer diameter D of 34 mm and a length L of 1 m.
Are engraved on both ends at intervals D (for example, 5 cm), and at the center with three intervals at intervals D1 (for example, 10 cm). Then, in the same manner as described above, as shown in FIG.
Undercoat 10 of Ni + Cr alloy of 0 μm, for example, thickness 3
An Al ₂ O ₃ insulator film 11 having a thickness of 00 μm and a heating element film 12 of Ni + Cr having a thickness of 120 μm, for example, are sequentially sprayed. Finally, as shown in FIG. 5, this is an example in which the thickness t1 is polished so that the film thickness of the heating element film 12 is, for example, 100 μm.

An electric power of 1 kW is applied to this heating element, and the result of measuring the surface temperature of the stainless steel tube 3 with a thermocouple is shown in FIG.
From the figure, it can be seen that the temperature uniform band expands as in the temperature characteristic A as compared with the temperature characteristic B when the grooves 4 are provided at equal intervals.

[0018]

As described above, according to the present invention, by providing the groove in the base material, it is possible to improve the control and accuracy of the resistance value.

Further, without using masking, it is possible to easily deal with one product or a large number of products and to reduce the cost.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a thermal spray heating element embodying the present invention.

FIG. 2 is a sectional view taken along the line AA ′ of FIG.

FIG. 3 is a perspective view showing another example of the thermal spray heating element embodying the present invention.

FIG. 4 is a cross-sectional view showing a state before polishing the groove.

FIG. 5 is a cross-sectional view showing a state after polishing the groove.

FIG. 6 is a measurement result diagram illustrating the temperature dependence of the groove spacing.

[Explanation of symbols]

 D ... Groove spacing P ... Heating element pattern t, t1 ... Polishing thickness 1 ... Aluminum plate 2, 4 ... Groove 3 ... Stainless tube 10 ... Undercoat 11 ... Insulator film 12 ... Heater film 13, 14 ... Terminal 15 ... Resistor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Koya 11-1 Haneda-Asahicho, Ota-ku, Tokyo Ebara Corporation (72) Inventor Kazuya Kobayashi 1-1-1 Gyoda, Funabashi, Chiba Toka Incorporated (72) Inventor Junichi Takeuchi 1-1-1, Gyoda, Funabashi, Chiba Prefecture Tokaro Co., Ltd. (72) Inventor Masaya Kumakawa 1-1-1, Gyoda, Funabashi, Chiba Tokaro Co., Ltd.

Claims (3)

[Claims] 1. A groove having an arbitrary depth and an arbitrary width is preliminarily formed on a surface of a base material of an insulating material, and a conductive material is sprayed on the groove, and then the sprayed conductive material is formed. A method for producing a thermal spray heating element, characterized in that the surface of the coating film is polished to leave the coating film only inside the groove and a resistor is formed on the base material with a conductive coating film having a film thickness arbitrarily determined. 2. A groove having an arbitrary depth and an arbitrary width is preliminarily formed on the surface of a base material of a conductive material, and an insulating material and a conductive material are sequentially sprayed to the groove, and then the thermal spraying is performed. Of the sprayed heating element, characterized in that the resistive material is formed on the base material by a conductive coating having a film thickness arbitrarily determined by leaving the coating film only inside the groove by polishing the surface of the conductive material. Manufacturing method. 3. The method for manufacturing a thermal spray heating element according to claim 1, wherein the intervals between the grooves are arbitrary.