JPH03182091A - Manufacture of electric heater - Google Patents

Abstract

PURPOSE:To provide a heater with heater coil capable of being fixed simply and firmly, wherein heat loss is small and overheat is not likely to occur, by installing the heater coil recessed in a molding of ceramic fiber, and impregnating thin molding with a specified hardening agent. CONSTITUTION:When the side of a heater coil 2 is pressed to a molding 1 of crystallized ceramic fiber, part of the coil 2 is recessed in the molding 1 while its surface is held flat. If in this condition the molding 1 is impregnated with a hardening agent containing colloidal silica followed by drying, the coil 2 is fixed simply and firmly, and an electric heater is accomplished with ensures that heat loss is small because no mortar is used and that overheating is not likely to occur.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing an electric heater for industrial and domestic use.

[Conventional technology]

Ceramic fiber has excellent fire resistance, heat insulation, and heat shock properties, and is lightweight and has a small heat capacity, so it is used for divine purposes as a fire-resistant insulation material.

A bite-shaped body is also known, in which ceramic fibers are dispersed in water together with a binding material, the bottom is shaped into an arbitrary shape by a suction filtration method, and then dried.

As shown in Fig. 3, an electric heater in which a heater coil made of a coiled heating wire is attached to the surface of the molded body is produced by making a groove on the surface of the molded body 1 and fitting the heater coil 2 into the groove. As shown in FIG. 4, the heater coil 2 is embedded along the surface of the molded body 1 when forming the bottom of the molded body 1, and as shown in FIG.
As shown in Fig. 6, a shallow groove is made on the surface of the molded body 1, a heater fill 2 is inserted into the groove, and the heater coil 2 is fixed with mortar 3. be.

When manufacturing these electric heaters, the electric heater shown in Figure 3 requires time to process the groove and fit the heater coil, and since the heater coil is not fixed in the groove, the heater coil may come out of the groove during use. Easy to go out,
In the electric heater shown in Figure 4, the heater coil is less exposed from the surface of the molded product, so overheating of the heater coil is likely to occur.In the electric heater shown in Figure 5, it is difficult to position the heater coil on the surface of the molded product, and it is difficult to keep it in the specified position. The electric heater shown in Figure 6 requires time and effort to fix with mortar.
It takes a long time to process the grooves, and since it is fixed with mortar, it has the disadvantage of large heat loss due to the mortar, similar to the one shown in Fig. 5.

[Problem to be solved by the invention]

An object of the present invention is to provide a method for manufacturing an electric heater that allows a heater coil to be easily and firmly fixed to the surface of a molded product, has low heat loss because no mortar is used, and does not cause overheating. be.

[Means to solve the problem]

The means according to the present invention presses the side surface of a heater fill against the surface of a ceramic fiber molded body in which fibers are crystallized, causing a part of the heater fill to sink into the molded body, and then contains colloidal silica in the molded body. The method of manufacturing an electric heater includes impregnating it with a curing agent and drying it.

As the ceramic fiber used in the present invention, a ceramic fiber that can be crystallized is used.

These ceramic fibers include alumina fibers containing approximately 50% or more of α-alumina, silica-alumina fibers,
Well-known ceramic fibers such as silica-alumina-zirconia can be used. For crystallization, it is preferable that the molded body is heated and then crystallized, and it is preferable that 30% or more of the fibers are crystallized.

The depression depth of the heater fill into the molded body can be appropriately selected depending on the purpose of use, but it is usually about 173 to 172 degrees of the outer diameter of the heater coil.

The curing agent may be impregnated only on the surface of the molded body in which the heater fill is depressed, or may be impregnated throughout the molded body.

[Effect]

For non-crystallized ceramic fiber compacts,
Since it has elasticity, the side surface of the heater coil 2 is attached to the molded body 1.
Even when pressed against the surface of the molded body 1, as shown in FIG.
Only the part of the surface that contacts the heater coil 2 is dented, and when the pressing force is removed, the surface returns to its original state. However, the crystallized molded body is hardened and brittle due to crystallization, so when the side of the heater coil 2 is pressed against it,
As shown in Fig. 1, the fibers in the part pressed by the heater fill 2 break and the heater coil 2 sinks in from the surface of the molded body 1, causing the fibers around the heater coil 2 to break. The heater coil 2 is held in a hanging state. When this molded body 1 is impregnated with a curing agent containing colloidal silica and dried, the heater coil 2 and the fibers are bonded through the colloidal silica, and each pitch of the heater coil 2 is securely fixed to the molded body 1. It becomes something.

[Example]

1 molded body of alumina-siliceous ceramic fiber
It was crystallized by heat treatment at 200C for 1 hour.

Crystallized dust was 35%. The side surface of the heater fill was pressed against this molded body, and the heater fill was fitted so as to be recessed by 1/3 of its outer diameter. The surface of the heater fill of this compact was impregnated with colloidal silica containing 40% by weight of silica as a solid content, and dried at 120C for 24 hours.The heater coil was peeled off from the surface of the compact. However, the fibers of the molded body in contact with the heater coil peeled off while adhering to the heater coil, and the heater fill was firmly fixed to the molded body.

〔Effect of the invention〕

According to the present invention, it is possible to provide a method for manufacturing an electric heater in which a heater fill can be easily and reliably fixed not only to the flat surface of a ceramic fiber molded body but also to curved surfaces such as the outer periphery and inner periphery of a cylinder.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams of the method for manufacturing an electric heater of the present invention, in which FIG. 1 shows a state in which the heater coil is pressed against the molded body and is fitted into the molded body, and FIG. The heater coil is shown fixed to the molded body by the hardening agent. FIGS. 3 to 6 are explanatory diagrams of a conventional state in which a heater coil is attached to a molded body, and FIG. 7 is an explanatory diagram of a state in which a heater coil is pressed against a non-crystallized ceramic fiber molded body. 1...t2. Shape 2...Heater coil 3...Mortar Applicant Isolite Kogyo Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Procedural amendment (voluntary)

Claims (1)

[Claims] (1) The side surface of the heater coil is pressed against the surface of the ceramic fiber molded body in which the fibers have been crystallized, causing a part of the heater coil to sink into the molded body, and then the hardening agent containing colloidal silica is applied to the molded body. A manufacturing method for an electric heater that impregnates and dries the water.