JPH0136240B2 - - Google Patents
Info
- Publication number
- JPH0136240B2 JPH0136240B2 JP56086106A JP8610681A JPH0136240B2 JP H0136240 B2 JPH0136240 B2 JP H0136240B2 JP 56086106 A JP56086106 A JP 56086106A JP 8610681 A JP8610681 A JP 8610681A JP H0136240 B2 JPH0136240 B2 JP H0136240B2
- Authority
- JP
- Japan
- Prior art keywords
- hot plate
- powder
- embedded
- heating wire
- electrical insulating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000843 powder Substances 0.000 claims description 38
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 24
- 238000010438 heat treatment Methods 0.000 claims description 15
- 239000011521 glass Substances 0.000 claims description 13
- 239000000395 magnesium oxide Substances 0.000 claims description 12
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 6
- 229910021193 La 2 O 3 Inorganic materials 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims description 2
- 230000008018 melting Effects 0.000 claims description 2
- 238000010298 pulverizing process Methods 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims description 2
- 238000009413 insulation Methods 0.000 description 8
- 238000000034 method Methods 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000010292 electrical insulation Methods 0.000 description 2
- 239000010445 mica Substances 0.000 description 2
- 229910052618 mica group Inorganic materials 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Landscapes
- Resistance Heating (AREA)
- Glass Compositions (AREA)
Description
本発明は、埋込型熱板に関し、特に絶縁特性に
優れ、かつ寿命の長い埋込型熱板を提供するもの
である。
一般に現在使用されている熱板には、
シーズヒータを熱板内部に鋳込む方式
電熱線をマイカ板に巻いて作るマイカヒータ
等を熱板に密着させる方式
埋込み方式
の方式がある。しかし、寿命や、熱板の温度分布
の面からの埋込み方式が優れており、ヨーロツ
パ等では、家庭用コンロの主流を占めているのが
実情である。
第１図に、従来の埋込型熱板を示す。熱板１の
裏面に溝２が形成されてあり、この溝２の中央部
に電熱線３を設置し、溝２と電熱線３の間にマグ
ネシア等の電気絶縁粉末４が充填されている。
この様な構造を有する従来の埋込型熱板では、
開口面積が広く、大気と接する部分が大きいた
め、電気絶縁粉末４として、通常使用するマグネ
シア等の粉末を使用すると、電気絶縁粉末４が吸
湿し、絶縁劣化をきたす。
このため、本発明者らは、電気絶縁粉末とし
て、CaO、B2O3およびSiO2を主成分とするガラ
ス粉末を添加したマグネシア粉末を用いることに
より、埋込型熱板の絶縁特性が著しく向上すると
いう結論を得ている。
しかし、上記の電気絶縁粉末４を使用した埋込
型熱板では、添加したガラス成分と電熱線３と
が、徐々に反応し、電熱線３の寿命を低下させる
という欠点を有していた。
本発明は、上記従来の欠点を解消し、所期の目
的を達成する埋込型熱板を提供するものである。
本発明者らは、電気絶縁粉末について各種検討
した結果、NiO、CoO、WO3、Nb2O5、Y2O3、
CeO2、La2O3の群から選ばれる少なくとも一種
の酸化物と、CaO、B2O3およびSiO2を主成分と
するガラス粉末とを添加したマグネシア粉末を電
気絶縁粉末として用いることにより、絶縁特性に
優れ、かつ寿命の長い埋込型熱板を得ることがで
きるという結論を得た。
これは、上記電気絶縁粉末を使用すると、製造
工程中または使用初期の段階で、電熱線と上記酸
化物とが反応し、電熱線表面に緻密で安定な保護
被膜が形成され、この結果、従来見られた電熱線
とガラス成分との反応が抑制され、寿命が長くな
るためであると想定される。
一方、絶縁特性については、ガラス粉末がマグ
ネシア粉末を被覆するため保障され、優れた特性
を維持することができる。
以下、本発明の具体的な実施例について説明す
る。
実施例
CaOとB2O3及びSiO2を重量比で38.3対31.5対
30.2の割合で配合し、1200℃で溶融したのち、粉
砕し、ガラス粉末を準備した。
このガラス粉末とNiOを電融マグネシア粉末に
対して重量比でそれぞれ10％及び１％添加し、均
一に混合し、電気絶縁粉末４を準備した。
あらかじめ所定の長さに伸ばした電熱線３を熱
板１の溝２の中央に設置したのち、上記電気絶縁
粉末４を充填し、振動を加え、充填密度を上げた
のちプレス成型した。
最終工程として、プレス成型した熱板１を1000
℃の温度で１時間熱処理し、埋込型熱板を完成し
た。
なお、比較のために、従来例として、電融マグ
ネシア粉末のみの電気絶縁粉末４を使用した場
合、さらに比較例として、上記のCaO、B2O3、
SiO2を主成分とするガラス粉末を添加した電融
マグネシア粉末を電気絶縁粉末４として使用した
場合について、それぞれ、埋込型熱板を完成し
た。
完成したそれぞれの埋込型熱板を、40℃、相対
湿度95％の多湿雰囲気中に投入し、室温での絶縁
抵抗の経時変化を測定した。この結果を第２図に
示した。第２図において、ａは実施例、ｂは従来
例、ｃは比較例を示す。
また、熱板の温度が600℃になる様に調整し、
20分on−10分offのサイクルテストによる寿命試
験を行い、電熱線が断線するまでのサイクル（寿
命）を調べた。
この結果を第１表に示す。
The present invention relates to an embedded hot plate, and particularly provides an embedded hot plate that has excellent insulation properties and has a long life. Generally, there are two types of hot plates currently in use: a method in which a sheathed heater is cast inside the hot plate, a method in which a mica heater made by winding heating wires around a mica plate is attached closely to the hot plate, and a method in which it is embedded. However, the embedded method is superior in terms of lifespan and temperature distribution of the heating plate, and in reality, it is the mainstream of home stoves in Europe and other countries. FIG. 1 shows a conventional embedded hot plate. A groove 2 is formed on the back surface of the hot plate 1, a heating wire 3 is installed in the center of the groove 2, and an electrically insulating powder 4 such as magnesia is filled between the groove 2 and the heating wire 3. In the conventional embedded type hot plate with such a structure,
Since the opening area is large and the portion in contact with the atmosphere is large, if a commonly used powder such as magnesia is used as the electrical insulating powder 4, the electrical insulating powder 4 will absorb moisture and cause insulation deterioration. Therefore, the present inventors have found that by using magnesia powder to which glass powder containing CaO, B2O3 , and SiO2 as main components is added as electrical insulating powder, the insulating properties of the embedded hot plate can be significantly improved. The conclusion is that it will improve. However, the embedded hot plate using the electrically insulating powder 4 described above has the disadvantage that the added glass component and the heating wire 3 gradually react with each other, reducing the lifespan of the heating wire 3. The present invention provides an embedded hot plate that overcomes the above-mentioned conventional drawbacks and achieves the intended purpose. As a result of various studies on electrical insulating powders, the present inventors found that NiO, CoO, WO 3 , Nb 2 O 5 , Y 2 O 3 ,
By using magnesia powder to which at least one oxide selected from the group of CeO 2 and La 2 O 3 and glass powder whose main components are CaO, B 2 O 3 and SiO 2 are added as an electrical insulating powder, It was concluded that it is possible to obtain an embedded hot plate with excellent insulation properties and a long life. This is because when the electrical insulating powder is used, the heating wire reacts with the oxide during the manufacturing process or at the initial stage of use, forming a dense and stable protective film on the surface of the heating wire. It is assumed that this is because the observed reaction between the heating wire and the glass component is suppressed, resulting in a longer life. On the other hand, the insulation properties are guaranteed because the glass powder covers the magnesia powder, and excellent properties can be maintained. Hereinafter, specific examples of the present invention will be described. Example: CaO, B 2 O 3 and SiO 2 in a weight ratio of 38.3 to 31.5
They were blended at a ratio of 30.2, melted at 1200°C, and then ground to prepare glass powder. This glass powder and NiO were added in a weight ratio of 10% and 1%, respectively, to the fused magnesia powder and mixed uniformly to prepare electrical insulation powder 4. A heating wire 3 stretched to a predetermined length was placed in the center of the groove 2 of the hot plate 1, then filled with the electrical insulating powder 4, vibrated to increase the packing density, and then press-molded. As the final process, the press-molded hot plate 1 is
Heat treatment was performed at a temperature of ℃ for 1 hour to complete an embedded hot plate. For comparison, as a conventional example, the electric insulating powder 4 made of only electrofused magnesia powder is used, and as a comparative example, the above-mentioned CaO, B 2 O 3 ,
In each case, an embedded hot plate was completed using electrofused magnesia powder to which glass powder containing SiO 2 as a main component was used as electrical insulating powder 4. Each completed embedded hot plate was placed in a humid atmosphere at 40°C and 95% relative humidity, and changes in insulation resistance over time at room temperature were measured. The results are shown in FIG. In FIG. 2, a shows an example, b shows a conventional example, and c shows a comparative example. Also, adjust the temperature of the hot plate to 600℃,
A lifespan test was conducted using a cycle test of 20 minutes on and 10 minutes off, and the cycle (life) until the heating wire broke was investigated. The results are shown in Table 1.
【表】
第２図および第１表から明らかなように、実施
例の埋込型熱板は、多湿雰囲気中に放置しても、
絶縁抵抗は、ほとんど低下せず、高い絶縁特性を
維持した。
また、比較例の埋込型熱板と比較して、寿命は
長くなつた。
このように、NiOはガラス粉末を添加した電融
マグネシア粉末を電気絶縁粉末として用いた埋込
型熱板の寿命を長くすることが明らかとなつた。
なお、実施例で示したNiO以外に、CoO、
Nb2O5、WO3、Y2O3、CeO2、La2O3から選ばれ
る酸化物であつても同様の傾向を示した。
また、ガラス粉末として、実施例で示した
CaO、B2O3、SiO2を主成分とするものに代えて、
CaOとB2O3を主成分とするものでもよい。
以上の説明から明らかなように、NiO、CoO、
WO3Nb2O5、Y2O3、CeO2、La2O3の群から選ば
れる少くとも一種の酸化物とCaO、B2O3、SiO2
を主成分とする物質を溶融・粉砕したガラス粉末
とを添加したマグネシア粉末を電気絶縁粉末とし
て用いることにより、絶縁特性に優れた、かつ寿
命の長い埋込型熱板を提供することができる。ま
た、溶融・粉砕した後のガラス粉末と酸化物とを
マグネシアに添加することにより、ガラス粉末の
主成分の物質と酸化物とが化学反応して他の物質
に変わり、特に酸化物が本来の電熱線の保護被膜
形成するのを阻害することを抑制できる。[Table] As is clear from Fig. 2 and Table 1, the embedded hot plate of the example has
Insulation resistance hardly decreased and high insulation properties were maintained. Furthermore, the lifespan was longer than that of the embedded hot plate of the comparative example. In this way, it has become clear that NiO extends the life of an embedded hot plate using fused magnesia powder added with glass powder as an electrically insulating powder. In addition to NiO shown in the examples, CoO,
A similar tendency was observed even with oxides selected from Nb 2 O 5 , WO 3 , Y 2 O 3 , CeO 2 , and La 2 O 3 . In addition, as glass powder,
Instead of those whose main components are CaO, B 2 O 3 and SiO 2 ,
A material containing CaO and B 2 O 3 as main components may also be used. As is clear from the above explanation, NiO, CoO,
At least one oxide selected from the group of WO 3 Nb 2 O 5 , Y 2 O 3 , CeO 2 , La 2 O 3 and CaO, B 2 O 3 , SiO 2
By using magnesia powder as an electrical insulating powder, it is possible to provide an embedded hot plate with excellent insulating properties and a long life. In addition, by adding glass powder and oxide after melting and pulverization to magnesia, the main component of the glass powder and oxide react chemically and change into other substances, especially when the oxide changes from its original state. It is possible to suppress the formation of a protective film on the heating wire.
第１図は一般的な埋込型熱板を示す。第２図は
本発明の実施例および従来例、比較例の埋込型熱
板における多湿雰囲気中に放置した時の室温での
絶縁抵抗値の経時変化を示す。
１……熱板、２……溝、３……電熱線、４……
電気絶縁粉末。
FIG. 1 shows a typical embedded hot plate. FIG. 2 shows changes over time in insulation resistance values at room temperature when the embedded hot plates of the example of the present invention, the conventional example, and the comparative example were left in a humid atmosphere. 1...Hot plate, 2...Groove, 3...Heating wire, 4...
Electrical insulation powder.
Claims (1)
を電気絶縁粉末で埋設してなる埋込型熱板におい
て、前記電気絶縁粉末として、NiO、CoO、
WO3、Nb2O5、Y2O3、CeO2、La2O3の群から選
ばれる少なくとも一種の酸化物と、CaO、B2O3、
SiO2を主成分とする物質を溶融・粉粋したガラ
ス粉末とを添加したマグネシア粉末を用いてなる
埋込型熱板。1. In an embedded hot plate in which a heating wire is embedded with electrical insulating powder in the center of a groove installed on the back side of the hot plate, the electrical insulating powder may include NiO, CoO,
At least one oxide selected from the group of WO 3 , Nb 2 O 5 , Y 2 O 3 , CeO 2 , La 2 O 3 and CaO, B 2 O 3 ,
An embedded hot plate made of magnesia powder added with glass powder made by melting and pulverizing a substance whose main component is SiO 2 .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8610681A JPS57202080A (en) | 1981-06-03 | 1981-06-03 | Buried type hot plate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8610681A JPS57202080A (en) | 1981-06-03 | 1981-06-03 | Buried type hot plate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57202080A JPS57202080A (en) | 1982-12-10 |
| JPH0136240B2 true JPH0136240B2 (en) | 1989-07-28 |
Family
ID=13877445
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8610681A Granted JPS57202080A (en) | 1981-06-03 | 1981-06-03 | Buried type hot plate |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57202080A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5564388A (en) * | 1978-11-07 | 1980-05-15 | Matsushita Electric Ind Co Ltd | Sheathed heater and method of manufacturing same |
| JPS5590011A (en) * | 1978-12-28 | 1980-07-08 | Matsushita Electric Ind Co Ltd | Insulator for burying metallic heater wire and method of manufacturing same |
| JPS5590095A (en) * | 1978-12-28 | 1980-07-08 | Matsushita Electric Ind Co Ltd | Sheathed heater and method of fabricating same |
-
1981
- 1981-06-03 JP JP8610681A patent/JPS57202080A/en active Granted
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5564388A (en) * | 1978-11-07 | 1980-05-15 | Matsushita Electric Ind Co Ltd | Sheathed heater and method of manufacturing same |
| JPS5590011A (en) * | 1978-12-28 | 1980-07-08 | Matsushita Electric Ind Co Ltd | Insulator for burying metallic heater wire and method of manufacturing same |
| JPS5590095A (en) * | 1978-12-28 | 1980-07-08 | Matsushita Electric Ind Co Ltd | Sheathed heater and method of fabricating same |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57202080A (en) | 1982-12-10 |
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