【発明の詳細な説明】[Detailed description of the invention]
本発明は、鋳造の際に押湯の保温に用いる押湯
用発熱保温材（以下保温材という）の製造法に関
するものである。
従来より鋳造の際に、押湯のさめによる固化を
防止するため自己燃焼性物質からなる筒状の保温
材が用いられている。この保温材の備えねばなら
ぬ性質としては鋳型に湯を流し込み、これが固化
する以前まで適当な燃焼速度を有して、発熱温度
を一様に保持し、押湯の作用を良好にする必要が
ある。
保温材の燃焼速度が速すぎると、押湯の保温時
間が短くなり途中で押湯が固化してしまい製品に
巣ができたり、急激に発熱するため型くずれや変
形が生じ不適当な寸法の保温材を使用したのと同
様となり種々な点で不利益となる。また燃焼速度
が遅すぎると所定温度に発熱せず、押湯の保温が
不十分となるため多くの湯を要し歩留りが悪くな
る。
従来の保温材は、アルミニウム、酸化鉄、けい
砂等を混合してなる自己燃焼発熱性物質に必要に
応じて硝酸カリウム、硝酸ナトリウム等の燃焼促
進剤の適当添加したものを水ガラスで結合したも
のである。しかしながら結合剤の水ガラスが保温
材の配合材料である酸化珪素分と熱により反応し
て保温材が軟化し、型くずれや変形が起こつてい
た。また湯の保温を十分にするために燃焼速度を
むしろ速めにとつているので、どうしても保温時
間が不十分とならざるを得なかつた。
本発明は上記の問題点を改め、保温材の燃焼速
度を適当に調整して型くずれや変形を防止し、か
つ保温時間の十分なる保温材の製造法を提供する
ことを目的とする。
本発明は、アルミニウム粉、酸化鉄粉およびけ
い砂に石綿40〜85重量％と熱硬化性樹脂15〜60重
量％との混合物からなる保温材の燃焼速度調整剤
を２〜10重量％添加し、これを水ガラスで結合さ
せた後筒状に成形し、ついで乾燥する保温材の製
造法に関する。
本発明に用いる石綿は繊維のあまり長いものは
必要とせず、６クラス以下から粉末状のもので十
分である。また熱硬化性樹脂としては、フエノー
ル樹脂、メラミン樹脂、エポキシ樹脂、ポリエス
テル樹脂、フラン樹脂等が用いられ、これらの一
種でもよく又二種以上を混合したものでもよく特
に制限はない。
石綿と熱硬化性樹脂との混合物の作り方の例を
あげれば次の通りである。
石綿粉と熱硬化性樹脂粉とを混合機によつて
混合する。
熱硬化性樹脂ワニス中に石綿粉を添加して混
合し、加熱によつて溶剤を除去した後粉砕す
る。
なお、石綿と熱硬化性樹脂との混合物が用いら
れているクラツチフエーシング、ブレーキライニ
ング等の摩擦材の切削粉を利用することもでき、
これは廃材活用として非常に好ましい。石綿と熱
硬化性樹脂との配合割合は、石綿40〜85重量％、
熱硬化性樹脂15〜60重量％の範囲とされ、この範
囲から外れると保温材の燃焼速度を適当に調整す
ることができず形くずれや変形が生ずる。また石
綿と熱硬化性樹脂との混合物をアルミニウム粉、
酸化鉄およびけい砂に添加する量は、保温材の寸
法や形状によつて変わつてくるが、２〜10重量％
の範囲で用いられる。この範囲より少ないと目的
とする効果がでず、また多くなると発熱がさまた
げられ保温性が低下してしまう。
本発明の製造法においては、上記の各原料を混
合機にかけて十分に混合した後、木型または金型
を用いて円筒、楕円筒、円錐筒などの筒状に圧縮
成形し、同時に肉厚部の高さ方向にガス抜孔を適
当数設け、この成形体を300℃以下の温度で乾燥
して製品とする。なお、筒状体の下部に、角孔を
中央に設けた板状体を接合したネツク部を形成し
たものとすることもできる。
以下本発明の実施例を説明する。
実施例 １
アルミニウム粉50重量％、酸化鉄粉27重量％、
けい砂20重量％に摩擦材の切削粉（石綿75重量
％、フエノール樹脂25重量％の混合物）を３重量
％添加し、これらの混合物に対して水ガラスを23
重量％加えて十分に混合した。次にこれを外径
405mm、内径325mm、高さ325mmの寸法に圧縮成形
し、同時に肉厚部高さ方向に５φの孔を12ケ設け
た。そしてこの成形体を280℃で８時間乾燥し保
温材を得た。
比較例 １
アルミニウム粉51.6重量％、酸化鉄粉27.8重量
％、けい砂20.6重量％の混合物に対して水ガラス
を25重量％加えた。後は実施例１と同じ条件で保
温材を作つた。
実施例 ２
アルミニウム粉52重量％、酸化鉄粉26重量％、
けい砂15重量％、硝酸カリウム１重量％に石綿粉
65重量％とメラミン樹脂粉35重量％との混合粉を
６重量％添加し、これらの混合物に対して水ガラ
スを20重量％加えて十分に混合した。次にこれを
外径185mm、内径140mm、高さ140mmの寸法に圧縮
成形し、同時に肉厚部高さ方向に3.5φの孔を12
ケ設けた。そしてこの成形体を250℃で６時間乾
燥し保温材を得た。
比較例 ２
アルミニウム粉55.3重量％、酸化鉄粉27.6重量
％、けい砂16重量％、硝酸カリウム1.1重量％の
混合物に対して水ガラスを20重量％加えた。後は
実施例２と同じ条件で保温材を作つた。
実施例 ３
アルミニウム粉50重量％、酸化鉄粉25重量％、
けい砂15重量％、硝酸カリウム２重量％に摩擦材
の切削粉（石綿80重量％、フエノール樹脂15重量
％、メラミン樹脂５重量％の混合物）を８重量％
添加し、これらの混合物に対して水ガラスを25重
量％加えて十分に混合した。次にこれを外径140
mm、内径100mm、高さ100mmの寸法に圧縮成形し、
同時に肉厚高さ方向に３φの孔を10ケ設けた。そ
してこの成形体の250℃で５時間乾燥し保温材を
得た。
比較例 ３
アルミニウム粉54.3重量％、酸化鉄粉27.2重量
％、けい砂16.3重量％、硝酸カリウム2.2重量％
の混合物に対して水ガラスを25重量％加えた。後
は実施例３と同じ条件で保温材を作つた。
上記各実施例によるものとそれに対応する比較
例によるものとを用いて鋳造を行なつた結果を第
１表に示す。
The present invention relates to a method for manufacturing a heat-generating heat insulating material for a feeder (hereinafter referred to as "heat insulating material") used to keep the feeder warm during casting. Conventionally, during casting, a cylindrical heat insulating material made of a self-combustible material has been used to prevent solidification due to freezing of the riser. The properties that this heat insulating material must have include that when hot water is poured into the mold, it must have an appropriate combustion rate until it solidifies, maintain the heat generation temperature uniformly, and make the riser work well. be. If the burning speed of the heat insulating material is too fast, the heat retention time of the feeder will be shortened, causing the feeder to solidify midway through, creating cavities in the product, or causing the product to lose its shape and deform due to rapid heat generation, resulting in heat retention with inappropriate dimensions. This is the same as using the same material, and is disadvantageous in various respects. Furthermore, if the combustion rate is too slow, heat will not be generated to a predetermined temperature, and the feeder will not be kept sufficiently warm, requiring a large amount of hot water and resulting in poor yield. Conventional heat insulating materials are made by combining a self-combusting exothermic substance made of a mixture of aluminum, iron oxide, silica sand, etc., with appropriate additions of combustion accelerators such as potassium nitrate and sodium nitrate as necessary, and bonded with water glass. It is. However, the water glass binder reacts with the silicon oxide component of the heat insulating material due to heat, causing the heat insulating material to soften, causing it to lose its shape and become deformed. In addition, in order to keep the hot water sufficiently warm, the combustion rate was rather fast, so the heat retention time was inevitably insufficient. An object of the present invention is to correct the above-mentioned problems and provide a method for manufacturing a heat insulating material that prevents deformation and deformation by appropriately adjusting the burning rate of the heat insulating material, and has a sufficient heat retention time. The present invention adds 2 to 10% by weight of a combustion rate regulator for a heat insulating material made of a mixture of 40 to 85% by weight of asbestos and 15 to 60% by weight of a thermosetting resin to aluminum powder, iron oxide powder, and silica sand. , relates to a method for manufacturing a heat insulating material, which is bonded with water glass, formed into a cylindrical shape, and then dried. Asbestos used in the present invention does not need to have very long fibers, and powdered asbestos from class 6 or below is sufficient. Further, as the thermosetting resin, phenol resin, melamine resin, epoxy resin, polyester resin, furan resin, etc. are used, and there is no particular restriction, and one type of these resins may be used, or a mixture of two or more types thereof may be used. An example of how to make a mixture of asbestos and thermosetting resin is as follows. Asbestos powder and thermosetting resin powder are mixed using a mixer. Asbestos powder is added and mixed into a thermosetting resin varnish, the solvent is removed by heating, and the mixture is pulverized. It is also possible to use cutting powder from friction materials such as clutch facings and brake linings that use a mixture of asbestos and thermosetting resin.
This is a very preferable way to utilize waste materials. The blending ratio of asbestos and thermosetting resin is 40 to 85% by weight asbestos;
The thermosetting resin should be in a range of 15 to 60% by weight, and if it is out of this range, the burning rate of the heat insulating material cannot be adjusted appropriately, resulting in deformation or deformation. In addition, aluminum powder, a mixture of asbestos and thermosetting resin,
The amount added to iron oxide and silica sand varies depending on the size and shape of the insulation material, but is 2 to 10% by weight.
Used within the range of If the amount is less than this range, the desired effect will not be achieved, and if it is more than this, heat generation will be hindered and heat retention will be reduced. In the manufacturing method of the present invention, after thoroughly mixing the above-mentioned raw materials in a mixer, compression molding is performed using a wooden mold or metal mold into a cylindrical shape such as a cylinder, an elliptical cylinder, a conical cylinder, etc., and at the same time A suitable number of gas vent holes are provided in the height direction of the molded body, and the molded body is dried at a temperature of 300°C or less to produce a product. Note that a neck portion may be formed in the lower part of the cylindrical body by joining a plate-like body with a square hole in the center. Examples of the present invention will be described below. Example 1 50% by weight of aluminum powder, 27% by weight of iron oxide powder,
Add 3% by weight of friction material cutting powder (a mixture of 75% asbestos and 25% phenolic resin) to 20% by weight of silica sand, and add 23% of water glass to this mixture.
% by weight and mixed thoroughly. Next, set this as the outer diameter
It was compression molded to dimensions of 405 mm, inner diameter 325 mm, and height 325 mm, and at the same time, 12 holes of 5φ were made in the height direction of the thick wall part. This molded body was dried at 280°C for 8 hours to obtain a heat insulating material. Comparative Example 1 25% by weight of water glass was added to a mixture of 51.6% by weight of aluminum powder, 27.8% by weight of iron oxide powder, and 20.6% by weight of silica sand. After that, a heat insulating material was produced under the same conditions as in Example 1. Example 2 Aluminum powder 52% by weight, iron oxide powder 26% by weight,
15% by weight of silica sand, 1% by weight of potassium nitrate, and asbestos powder
6% by weight of a mixed powder of 65% by weight and 35% by weight of melamine resin powder was added, and 20% by weight of water glass was added to the mixture and thoroughly mixed. Next, this was compression molded to dimensions of outer diameter 185 mm, inner diameter 140 mm, and height 140 mm, and at the same time, 12 3.5φ holes were drilled in the height direction of the thick part.
I set it up. This molded body was then dried at 250°C for 6 hours to obtain a heat insulating material. Comparative Example 2 20% by weight of water glass was added to a mixture of 55.3% by weight of aluminum powder, 27.6% by weight of iron oxide powder, 16% by weight of silica sand, and 1.1% by weight of potassium nitrate. After that, a heat insulating material was produced under the same conditions as in Example 2. Example 3 50% by weight of aluminum powder, 25% by weight of iron oxide powder,
15% by weight of silica sand, 2% by weight of potassium nitrate, and 8% by weight of friction material cutting powder (a mixture of 80% by weight of asbestos, 15% by weight of phenol resin, and 5% by weight of melamine resin).
25% by weight of water glass was added to these mixtures and mixed thoroughly. Next, set this to an outer diameter of 140
Compression molded to dimensions of mm, inner diameter 100mm, height 100mm,
At the same time, 10 holes of 3φ were made in the thickness direction. The molded body was then dried at 250°C for 5 hours to obtain a heat insulating material. Comparative Example 3 Aluminum powder 54.3% by weight, iron oxide powder 27.2% by weight, silica sand 16.3% by weight, potassium nitrate 2.2% by weight
25% by weight of water glass was added to the mixture. After that, a heat insulating material was produced under the same conditions as in Example 3. Table 1 shows the results of casting using the above examples and the corresponding comparative examples.
【表】
本発明の製造法によつて得られる保温材は、従
来の組成に、石綿と熱硬化性樹脂の混合物を所定
量添加したので、燃焼速度を適当に調整して急激
な温度上昇を防止して型くずれや変形を防止し、
かつ燃焼時間が一様となつて押湯の保温時間を延
長し、鋳造製品の不良率が低下する効果が得られ
る。[Table] The heat insulating material obtained by the production method of the present invention has a predetermined amount of a mixture of asbestos and thermosetting resin added to the conventional composition, so the combustion rate can be adjusted appropriately to prevent a sudden temperature rise. prevents deformation and deformation,
In addition, the combustion time becomes uniform, the heat retention time of the riser is extended, and the rejection rate of cast products is reduced.