JP2652266B2 - Heating element manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a heating element used mainly as a heating source in appliances such as cookers and dryers.

[Conventional technology]

2. Description of the Related Art Conventionally, a method of manufacturing a heating element used as a heating source of a device such as a cooker or a dryer is described by setting a heating wire 2 in a wire mesh forming die 1 as shown in FIG. Was opened in water, the binder-added slurry was sucked, the heat insulating material was laminated, and then the mold was removed and dried.

However, in this manufacturing method, as shown in FIG. 4, the heating wire 2 is entirely covered with the heat insulating material 3, or as shown in FIG. Although it is possible to place the heating wire 2 on the upper side, if the heating wire 2 is further extended from the heat insulating material 3, the heating wire 2 is not firmly held by the heat insulating material 3 and cannot withstand shocks such as a heat cycle and a vibration test. Therefore, there was a problem that it was difficult.

[Problem to be solved by the invention]

The present invention has been made in order to solve the above-mentioned conventional problems, and it is possible to bring out the heating wire from the heat insulating material by about 2/3 or more. It is an object of the present invention to provide a method of manufacturing a heating wire that can have a structure that can sufficiently withstand shocks such as a cycle and a vibration test.

[Means for solving the problem]

The present invention comprises a method for manufacturing a heating element in which a heating element is partially embedded in a heat insulating material at least composed of an inorganic binder and inorganic fibers and / or inorganic powders. There is. First, an insulating material composed of at least an inorganic binder and an inorganic fiber and / or an inorganic powder is poured in a wet state into a mold in which a heating wire having a predetermined shape is set, and the heating wire is heated. 2 /
After exposing and fixing about 3 or more from the heat insulating material, it is a method of manufacturing a heating element that performs demolding and drying, and another method is a heat insulating material comprising at least an inorganic binder and inorganic fibers and / or inorganic powder. A kneaded material made of a material is used to form a plate-shaped seat, and the bottom of the heating wire is pressed into the uncured seat to expose about 2/3 or more of the heating wire from the kneaded material. This is from a method of manufacturing a heating element that holds a heating wire firmly by drying and solidifying the body.

〔Example〕

FIG. 1 is a perspective view for explaining a method of manufacturing a heating element according to a first embodiment of the present invention. The heating element includes a coil formed from a nichrome wire such as a Ni-Cr wire or an Fe-Cr-Al wire in advance. Line 2
The next heat insulating material 4 is kept in a wet state in a mold 5 in which is set inside, and is poured from the container 7 to form a heating element. In this case, it is preferable that water is added about three times or more of the heat insulating material. That is, the composition of the final product as the heat insulating material to be used is as follows.

a. Ceramic fiber: 30-50 parts by weight Alumina silicate fiber,
Alumina fiber, silica fiber, zirconia fiber, etc. b. Inorganic binder 30-50 parts by weight (← solid content) As inorganic binder, colloidal silica, colloidal alumina, etc. c. Inorganic (fire resistant) powder 10 3030 parts by weight As the inorganic powder, alumina, mullite, arica, etc. As described above, the heating wire 2 having a predetermined shape such as a coil shape is placed in the mold 5 in advance according to a predetermined wiring pattern. Stir and mix the heat insulating material 4 of
Pour it while keeping it in a wet state,
After being fixed with the heat insulating material 4 in a state of being exposed to a degree or more, demolding and drying are performed.

Here, it is preferable that the heat resistant temperature is at least 1,100 ° C. or more, and that the heating wire 2 is coated with a coating such as epoxy for corrosion protection.

In this case, as shown in FIG. 2, the heating wire 2 is fixed so that the heating wire 2 is embedded about 1/3 in the heat insulating material 4, that is, about 2/3 is protruded from the heat insulating material 4.
Is set in the mold 5 and the amount of the heat insulating material 4 kept in a wet state to be poured into the mold 5 is adjusted.

FIG. 6 is a sectional view of a main part of a heating element showing another embodiment of the present invention.

In the figure, reference numeral 2 denotes a coiled heating wire having a spiral shape, that is, a heating wire (winding diameter: 5 mm, heating wire diameter: 0.8 mm). The heating wire 2 is composed of 20 wt% of ceramic fiber and colloidal silica (30 mm).
% Solution) 70% by weight and 10% by weight of alumina powder were implanted and supported to a 1.5 mm depth in a 3 mm thick thin plate-shaped seat 4 ′ made of a ceramic material formed into a sheet. ing. Reference numeral 5 'denotes a thick plate-shaped tray-shaped seat made of a ceramic material obtained by adding water to 70% by weight of ceramic fiber and 30% by weight of colloidal silica (30% solution), which supports the thin seat 4'. It is.

The thin seat 4 'directly supporting the heating wire 2 is made of a raw sheet (green sheet) before the kneaded material is dried and solidified. It is formed by drying and solidifying. In this case, water is preferably added about 0.2 to 3.0 times of the heat insulating material.

On the other hand, for the thick seat body 5 ', a formed body obtained by forming the kneaded material into a required shape and then drying and solidifying the same is used. The thin seat 4 'supporting the heating element 2 is fixed to the thick seat 5' with an adhesive.

7 and 8 show a method of manufacturing the heating element having the above-described configuration.

In the figure, reference numeral 4 'denotes an unsolidified thin seat made of the above-mentioned kneaded ceramic material.
The heating wire 2 is spirally placed thereon, and a push plate 8 is placed thereon and pressed thereon. By this pressing operation, the bottom of the heating wire 2 is pressed into the seat 4 'of the green sheet and implanted. I do.

When the bottom of the heating element 2 is implanted in the seat 4 'of the green sheet as described above, a part of the kneaded material of the ceramic material forming the seat is plastically deformed so as to go around the inside of the coil. Therefore, the implanted portion of the coil is buried in the kneaded material. Therefore, when the seat 4 'with a heating wire is thereafter placed in a drying oven or the like to be dried and solidified, the heating wire 2 is firmly supported in a state of being implanted in the seat 4' made of a ceramic material. This heating wire supporting force is obtained mainly by the shrinkage force of the kneaded material during drying and solidification and the bonding force of the joining material. However, since the anchoring action due to the entanglement of the ceramic fibers is added, only the bottom of the heating wire is planted. Even if it is stuck, it is firmly supported by a thin seat.

The seat with a heating wire obtained in the above process is adhered to a separately formed thick seat with an adhesive to form a heating element, that is, an electric heater product.

Next, based on the above configuration, a heating element shown in FIG. 9 was produced, and a heating element shown in FIG. 10 was produced as a comparative example, and both were subjected to transient efficiency, shimmering effect, response by the following test method. Test results of thermal efficiency when speed was measured
It is shown in the table.

In the figure, 2 is a heating wire, 4 'is a thin seat,
5 'is a thick seat, and 10 is a glass ceramic plate. The test conditions were 100V-12A, 1200W rating. The inner diameter of the electric heater is 180 mm.

Transient efficiency Measures the time required to raise the temperature of the aluminum block to the specified temperature when the rated voltage heater is activated (test method by AHAM).

Shimmering efficiency Measure the energy consumption per hour when the heater input is intermittently operated so that the water of 2 is maintained at 95 ° C.

This is a comparison with the energy consumption of the immersion heater system that can be regarded as 100% efficiency.

Response speed Energize the heater until the temperature of the cold water rises to 80 ° C. 80 ℃
When the temperature reaches, the power supply is stopped, and the time until the water temperature returns to 80 ° C again is measured.

As shown in the above measurement results, it was recognized that the electric heater of the present example was superior to the heating element of the comparative example in terms of thermal efficiency in both the transient efficiency and the shimmering effect. In addition, in response speed, it was recognized that the cooling time after turning off the power was shorter in the present example than in the comparative example because heat loss to the seat body and the glass ceramic plate was smaller than in the comparative example. This also indicates that heat is efficiently radiated to the object to be heated.

These results are attributable to the buried depth of the heating wire, and as in the present embodiment, the heating element exposing more than 1/2, preferably about 2/3 or more of the coil diameter of the heating wire was used. It can be seen that is excellent in functionality, economy and safety as a heat source of the cooking device.

In the embodiment shown in FIG. 6, an example is shown in which a thin seat heating wire made of a ceramic material is implanted, and this is superposed on a thick seat made of another ceramic material. Alternatively, the heating wire may be directly implanted in the thick seat before being dried and solidified. In this case, the step of bonding the thin seat is unnecessary.

For example, sufficient coil supporting force can be obtained simply by implanting a heating wire of 5 mm into a seat of 3 mm thickness at a depth of 1.5 mm.

It is more advantageous to implant the heating wire in a thin seat and bond it to the thick seat to integrate it into the seat, simplifying the work of implanting the heating wire in the seat and improving the efficiency of the entire manufacturing process. is there.

Here, it is also preferable to use a heating element in which a heating wire is partially embedded in a bulk heat insulating material in which an inorganic binder or the like is mixed in Al ₂ O ₃ , SiO ₂ , TiO ₂ and a mixture thereof. is there. In that case, the insulation consists of short fibers, which are in bulk.

〔The invention's effect〕

According to the manufacturing method of the present invention described above, the heat insulating material is in the form of biting the heating wire, the heating wire can be held in a state of protruding more sufficiently than the heat insulating material, and the heat insulating material surface is uniform. Also, the heat expansion becomes uniform, a heat generating structure resistant to thermal and mechanical shocks can be obtained, and a heat generating body that can withstand shocks such as heat cycles and vibration tests can be provided.

As a result, according to the present invention, a heating element can be obtained as an efficient heating source in a device such as a cooker or a dryer, and further, there is an advantage that an apparatus for manufacturing the heating element is simple and a manufacturing cost is low.

Further, the reason why the heat generating wire is partially embedded in the heat insulating material in the present invention is that it is not necessary to provide a special fixing means while increasing heat radiation. Although it is preferable to expose the entire heating wire, there is a drawback that a separate fixing means must be used for that purpose. This is because it is.

Further, according to the configuration of the present invention, only the bottom of the heating wire is implanted in the seat made of the ceramic material and is firmly supported,
Since most of the heat is exposed, a heating element that has a strong coil support force and that exhibits high thermal efficiency by combining the heat dissipation by the exposed coil and the heat dissipation prevention action to the lower part by the seat body is obtained. Can be

In addition, in the present invention, since a ceramic material having excellent electrical insulation, heat resistance, thermal shock resistance, and the like is used for the supporting body for the heating wire, the main part of the heating element can be formed by at least the sitting body alone. There is an advantage that the heater can be configured, and a pedestal in which a predetermined groove is formed in advance like a conventional heating element is omitted, so that the heater structure can be greatly simplified.

Further, according to the manufacturing method of the present invention, a kneaded material prepared with a ceramic material is used for a seat body into which a heating wire is implanted, and when the heating wire is in an unsolidified state, the heating wire is press-fitted and planted. Since the coil is dried and solidified to express the coil supporting force, the bottom of the heating wire is implanted very shallowly with respect to the seat body, and the heating wire is firmly supported with most of the coil exposed. be able to. In addition, since the operation for forming the implanted groove of the heating wire becomes unnecessary, it is possible to contribute to improvement and improvement of the manufacturing efficiency of the heating element.

 In addition to the above description, the present invention has the following effects.

(1). The heating wire is located only when the heating wire is located while the kneaded material comprising the inorganic binder and the heat insulating material at least composed of inorganic fibers and / or inorganic powders is in a wet state or an uncured state, and the kneaded material is dried to generate the heating wire. And the kneaded material can be integrated, so that the fixing of the heating wire can be facilitated, and there is no need to provide any special fastening means, so no fixing cost is required. Can simultaneously fulfill both roles.

(2). When fixing the heating wire with a kneaded material made of heat insulating material, by exposing about 2/3 or more of the heating wire from the kneaded material, the effect of fixing the heating wire and the heating effect appropriately and simultaneously Obtainable.

(3). Since the heating element is located in the kneaded material in the wet state or the uncured state, the positioning can be performed freely and easily and accurately.

[Brief description of the drawings]

FIG. 1 is a perspective view for explaining a method of manufacturing a heating element in one embodiment of the present invention, FIG. 2 is an enlarged sectional view of a main part of the heating element manufactured by the method of FIG. 1, and FIG. 4 and 5 are enlarged cross-sectional views of main parts of different heating elements manufactured by a conventional manufacturing method, and FIG. 6 is a view illustrating another embodiment. 7 and 8 are explanatory diagrams showing an example of the manufacturing process, FIG. 9 is a longitudinal sectional view of a test heating element according to the present invention, and FIG. It is a longitudinal cross-sectional view of the test heating element by an example. 2 ... heating wire, 4 ... heat insulating material, 4 '... thin seat, 5 ...
... mold, 5 '... thick seat, 8 ... push plate, 9 ... board.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Genhide Yoshizawa 500-1 Toyoshina, Toyoshina-cho, Minamiazumi-gun, Nagano Prefecture Nippon Electric Heating Co., Ltd. (56) References JP-A-1-157435 (JP, A) JP-A Sho 60-236486 (JP, A)

Claims (2)

(57) [Claims] 1. A kneaded material comprising an inorganic binder and a heat insulating material composed of at least an inorganic fiber and / or an inorganic powder is poured into a mold in which a heating wire having a predetermined shape is set in a wet state. And a method of manufacturing a heating element, in which about 2/3 or more of the heating wire is exposed and fixed from the kneaded material, and then the mold is removed and dried. 2. A plate-like seat body is formed from a kneaded material comprising an inorganic binder and a heat insulating material at least composed of inorganic fibers and / or inorganic powders.
A method for manufacturing a heating element in which the bottom of the heating wire is press-fitted to expose about 2/3 or more of the heating wire from the kneaded material, and the seat is dried and solidified to hold the heating wire firmly.