JP4326916B2

JP4326916B2 - Spherical casting sand

Info

Publication number: JP4326916B2
Application number: JP2003379057A
Authority: JP
Inventors: 阪口　　美喜夫; 茂夫仲井; 一彦木内; 明土井
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 2002-12-09
Filing date: 2003-11-07
Publication date: 2009-09-09
Anticipated expiration: 2023-11-07
Also published as: JP2004202577A

Description

本発明は、鋳鋼、鋳鉄、アルミニウム、銅およびこれらの合金等の鋳造用鋳型に使用される球状鋳物砂およびその製造方法、ならびに鋳造用鋳型に関する。 The present invention relates to a spherical casting sand used for casting molds such as cast steel, cast iron, aluminum, copper and alloys thereof, a method for producing the same, and a casting mold.

従来から鋳物砂として珪砂が広く使用されている。珪砂は鉱産物であるため形態が不定形であり、流動性に欠け、充填性が悪い。それゆえ、珪砂からなる鋳型の表面は荒く、従って、鋳造品（鋳物）の表面が荒れ、後工程である研磨工程への負荷が大きくなる。また、珪砂の構成鉱物である石英は鋳造時の熱負荷によりクリストバライト等へ結晶変態し、その時の体積変化により崩壊するため、珪砂は鋳物砂としての再生効率が低い。これらの問題を解決する手段として、球状鋳物砂（たとえば、特許文献１参照）や、高珪酸質球状鋳物砂およびその製造方法（たとえば、特許文献２参照）が開示されている。これらは、原料組成物を球形に造粒した後、ロータリーキルン等で焼成するものである。しかしながら、得られる鋳物砂の球形度は低く、そのため流動性および充填性は不充分であり、鋳物表面の荒れを改善する効果は小さい。また、焼結法であるため多くの開気孔が存在した吸水率の大きい多孔質のものしか得られない。その結果、鋳型の強度が不充分であったり、鋳型作製時に多量のバインダーを必要とするため、鋳物砂としての再生が困難となる。
特開平４−３６７３４９号公報（第２頁）特開平５−１６９１８４号公報（第２頁） Conventionally, silica sand has been widely used as foundry sand. Since silica sand is a mineral product, its form is irregular, lacks fluidity, and has poor filling properties. Therefore, the surface of the mold made of silica sand is rough, and therefore the surface of the cast product (casting) is rough, and the load on the polishing process, which is a subsequent process, is increased. In addition, quartz, which is a constituent mineral of silica sand, undergoes crystal transformation to cristobalite or the like due to the thermal load during casting and collapses due to volume change at that time, so that silica sand has low regeneration efficiency as foundry sand. As means for solving these problems, spherical casting sand (for example, see Patent Document 1), high silicic acid spherical casting sand and a method for producing the same (for example, see Patent Document 2) are disclosed. In these, the raw material composition is granulated into a spherical shape and then fired in a rotary kiln or the like. However, the spheroidity of the obtained foundry sand is low, so that the fluidity and filling properties are insufficient, and the effect of improving the roughness of the foundry surface is small. Moreover, since it is a sintering method, only a porous material having many open pores and high water absorption can be obtained. As a result, the strength of the mold is insufficient, or a large amount of binder is required at the time of mold production, making it difficult to regenerate as foundry sand.
JP-A-4-367349 (page 2) JP-A-5-169184 (2nd page)

本発明は、流動性に優れ、高強度かつ表面が平滑な鋳造用鋳型を製造することができる球状鋳物砂およびその製造方法、ならびに該鋳造用鋳型を提供することを課題とする。 An object of the present invention is to provide a spherical casting sand capable of producing a casting mold having excellent fluidity, high strength and smooth surface, a method for producing the same, and the casting mold.

本発明者らは、特定の成分組成および粒径を持ち、球形度が大きく、さらには吸水率が小さい耐火性粒子が鋳物砂として優れた性能を発揮することを見出し、本発明を完成させるに至った。 The present inventors have found that refractory particles having a specific component composition and particle size, a large sphericity, and a small water absorption rate exhibit excellent performance as foundry sand, and to complete the present invention. It came.

すなわち、本発明の要旨は、
〔１〕Ａｌ₂Ｏ₃およびＳｉＯ₂を主成分として含有してなり、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１〜１５、平均粒径が０．０５〜１．５ｍｍである火炎溶融法で製造された球状鋳物砂、
〔２〕Ａｌ₂Ｏ₃およびＳｉＯ₂を主成分として含有してなり、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１〜１５、平均粒径が０．０５〜０．５ｍｍ、球形度が０．９５以上である火炎溶融法で製造された球状鋳物砂、
〔３〕Ａｌ₂Ｏ₃およびＳｉＯ₂を主成分として含有してなり、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１〜１５、平均粒径が０．０５〜１．５ｍｍ、球形度が０．９５以上である球状鋳物砂、
〔４〕球形度が０．９８以上である前記〔１〕〜〔３〕いずれかに記載の球状鋳物砂を５０体積％以上含む鋳物砂、
〔５〕Ａｌ₂Ｏ₃およびＳｉＯ₂を主成分とする、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が０．９〜１７、平均粒径が０．０５〜２ｍｍの粉末粒子を、火炎中で溶融して球状化する工程を含む、前記〔１〕〜〔３〕いずれかに記載の球状鋳物砂の製造方法、
〔６〕前記〔１〕〜〔３〕いずれかに記載の球状鋳物砂または前記〔４〕に記載の鋳物砂を含んでなる鋳造用鋳型、
〔７〕前記〔６〕に記載の鋳型を用いて鋳造された鋳物、ならびに
〔８〕前記〔７〕に記載の鋳物からなる構造物、
に関する。 That is, the gist of the present invention is as follows.
[1] A flame melting method comprising Al ₂ O ₃ and SiO ₂ as main components, an Al ₂ O ₃ / SiO ₂ weight ratio of 1 to 15 and an average particle size of 0.05 to 1.5 mm. Produced spherical casting sand,
[2] It contains Al ₂ O ₃ and SiO ₂ as main components, the Al ₂ O ₃ / SiO ₂ weight ratio is 1 to 15, the average particle size is 0.05 to 0.5 mm, and the sphericity is 0. Spheroidal sand produced by the flame melting method, which is 95 or more,
[3] It contains Al ₂ O ₃ and SiO ₂ as main components, the Al ₂ O ₃ / SiO ₂ weight ratio is 1 to 15, the average particle size is 0.05 to 1.5 mm, and the sphericity is 0. Spheroidal sand that is 95 or more,
[4] Foundry sand containing 50% by volume or more of the spherical cast sand according to any one of [1] to [3], wherein the sphericity is 0.98 or more,
[5] Powder particles having Al ₂ O ₃ / SiO ₂ weight ratio of 0.9 to 17 and average particle size of 0.05 to 2 mm, mainly composed of Al ₂ O ₃ and SiO _2, are melted in a flame. A method for producing the spherical casting sand according to any one of the above [1] to [3], including a step of spheroidizing,
[6] A casting mold comprising the spherical foundry sand according to any one of [1] to [3] or the foundry sand according to [4],
[7] a casting cast using the mold according to [6], and [8] a structure made of the casting according to [7],
About.

本発明の球状鋳物砂は流動性に優れており、当該鋳物砂によれば、高強度かつ表面が平滑な鋳造用鋳型が得られる。 The spherical foundry sand of the present invention is excellent in fluidity, and according to the foundry sand, a casting mold having a high strength and a smooth surface can be obtained.

本発明の球状鋳物砂は大きく２つの態様からなる。第１の態様は、Ａｌ₂Ｏ₃およびＳｉＯ₂を主成分として含有してなり、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１〜１５、平均粒径が０．０５〜１．５ｍｍである、火炎溶融法で製造された球状鋳物砂である。また、第２の態様は、Ａｌ₂Ｏ₃およびＳｉＯ₂を主成分として含有してなり、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１〜１５、平均粒径が０．０５〜１．５ｍｍ、球形度が０．９５以上である球状鋳物砂である。 The spheroidal sand of the present invention has two major aspects. First aspect, and also contains Al ₂ O ₃ and SiO ₂ as a main component, Al ₂ O ₃ / SiO ₂ weight ratio of 1 to 15, an average particle diameter of 0.05 to 1.5 mm, It is spheroidal sand produced by the flame melting method. Further, the second embodiment contains Al ₂ O ₃ and SiO ₂ as main components, the Al ₂ O ₃ / SiO ₂ weight ratio is 1 to 15, the average particle size is 0.05 to 1.5 mm, Spherical casting sand having a sphericity of 0.95 or more.

本発明の球状鋳物砂は、特定の成分組成および平均粒径を持ち、球形度が大きい点に大きな特徴の１つを有する。かかる構成を有することから、流動性に優れ、高強度かつ表面が平滑な鋳造用鋳型の製造が可能となる。また、従来に比べて少ないバインダー量で鋳型を製造することができ、再生が容易である。 The spheroidal sand of the present invention has a specific component composition and average particle size, and has one of the great features in that it has a large sphericity. With such a configuration, it is possible to produce a casting mold having excellent fluidity, high strength and a smooth surface. In addition, the mold can be manufactured with a smaller amount of binder than in the prior art, and is easy to regenerate.

本発明の球状鋳物砂の形状である球状とは、球形度０．８８以上、好ましくは０．９０以上のものをいう。球状であるか否かについては、たとえば、後述の実施例に記載するように、鋳物砂を光学顕微鏡やデジタルスコープ（たとえば、キーエンス社製、ＶＨ−８０００型）等で観察し、判定することができる。 The spherical shape which is the shape of the spherical casting sand of the present invention refers to a sphericity of 0.88 or more, preferably 0.90 or more. Whether or not it is spherical can be determined by observing the foundry sand with an optical microscope or a digital scope (for example, VH-8000, manufactured by Keyence Corporation), for example, as described in Examples below. it can.

本発明の球状鋳物砂はＡｌ₂Ｏ₃およびＳｉＯ₂を主成分とするが、ここで「主成分」とは、Ａｌ₂Ｏ₃およびＳｉＯ₂が合計量で鋳物砂全体の全成分中に８０重量％以上含有されていることをいう。 The spheroidal molding sand of the present invention contains Al ₂ O ₃ and SiO ₂ as main components. Here, the “main component” means that the total amount of Al ₂ O ₃ and SiO ₂ is 80% in the total components of the casting sand. It means that it is contained by weight% or more.

本発明の球状鋳物砂の主成分であるＡｌ₂Ｏ₃およびＳｉＯ₂の含有量としては、耐火性の向上という観点から、それらの合計量として、球状鋳物砂の全成分中、好ましくは８５〜１００重量％、より好ましくは９０〜１００重量％である。 The content of Al ₂ O ₃ and SiO ₂ as the main component of the spherical molding sand of the present invention, from the viewpoint of improvement of fire resistance, as their total amount, the total component of the spherical molding sand, preferably 85 to 100% by weight, more preferably 90-100% by weight.

また、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率は１〜１５である。耐火性および鋳物砂の再生効率の向上の観点から、１．２〜１２が好ましく、１．５〜９がより好ましい。 The Al ₂ O ₃ / SiO ₂ weight ratio is 1 to 15. From the viewpoint of improvement in fire resistance and casting sand regeneration efficiency, 1.2 to 12 is preferable, and 1.5 to 9 is more preferable.

なお、本発明の球状鋳物砂に主成分以外の成分として含まれ得るものとしては、たとえば、ＣａＯ、ＭｇＯ、Ｆｅ₂Ｏ₃、ＴｉＯ₂、Ｋ₂Ｏ、Ｎａ₂Ｏ等の金属酸化物が挙げられる。これらは、出発原料として使用する、たとえば、後述の原料に由来するものである。ＣａＯとＭｇＯが含まれる場合、球状鋳物砂の耐火性の向上の観点から、それらの含有量としては合計量として５重量％以下が好ましい。Ｆｅ₂Ｏ₃とＴｉＯ₂が含まれる場合、それらの含有量としてはそれぞれ５重量％以下が好ましい。また、Ｆｅ_２Ｏ_３の含有量は２．５重量％以下がより好ましく、２重量％以下がさらに好ましい。Ｋ₂ＯとＮａ₂Ｏが含まれる場合、それらの含有量としては合計量として３重量％以下が好ましく、より好ましくは１重量％以下である。 Incidentally, as may be included as a component other than the main component in the spherical molding sand of the present invention, for _{example, CaO, MgO, Fe 2 O} 3, TiO 2, K 2 O, metal oxides Na ₂ O, etc. mentioned It is done. These are used as starting materials, for example, derived from the materials described below. When CaO and MgO are included, the total content is preferably 5% by weight or less from the viewpoint of improving the fire resistance of the spherical casting sand. When Fe ₂ O ₃ and TiO ₂ are contained, their content is preferably 5% by weight or less. Further, the content of Fe ₂ O ₃ is more preferably 2.5% by weight or less, and further preferably 2% by weight or less. When K ₂ O and Na ₂ O are contained, the total content is preferably 3% by weight or less, more preferably 1% by weight or less.

本発明の球状鋳物砂の平均粒径（ｍｍ）は０．０５〜１．５ｍｍの範囲である。０．０５ｍｍ未満になると鋳型の製造に多くのバインダーを必要とし、鋳物砂として再生するのが困難となるため好ましくない。一方、１．５ｍｍを超えると鋳型の空隙率が大きくなり、鋳型強度の低下に繋がることから好ましくない。球状鋳物砂の再生効率を高める観点から、０．０７５〜１．５ｍｍが好ましく、一方、鋳型強度を高める観点から、０．０５〜１ｍｍが好ましい。再生効率と鋳型強度の両者を高める観点から、０．０５〜０．５ｍｍがより好ましく、０．０５〜０．３５ｍｍがさらに好ましい。 The average particle size (mm) of the spherical casting sand of the present invention is in the range of 0.05 to 1.5 mm. If it is less than 0.05 mm, a large amount of binder is required for the production of the mold, and it becomes difficult to regenerate as foundry sand. On the other hand, if it exceeds 1.5 mm, the porosity of the mold increases, which leads to a decrease in mold strength. From the viewpoint of increasing the recycling efficiency of the spherical casting sand, 0.075 to 1.5 mm is preferable, and from the viewpoint of increasing the mold strength, 0.05 to 1 mm is preferable. From the viewpoint of increasing both the regeneration efficiency and the mold strength, 0.05 to 0.5 mm is more preferable, and 0.05 to 0.35 mm is more preferable.

前記平均粒径は以下のようにして求めることができる。すなわち、球状鋳物砂粒子の粒子投影断面からの球形度＝１の場合は直径（ｍｍ）を測定し、一方、球形度＜１の場合はランダムに配向させた球状鋳物砂粒子の長軸径（ｍｍ）と短軸径（ｍｍ）を測定して（長軸径＋短軸径）／２を求め、任意の１００個の球状鋳物砂粒子につき、それぞれ得られた値を平均して平均粒径（ｍｍ）とする。長軸径と短軸径は、以下のように定義される。粒子を平面上に安定させ、その粒子の平面上への投影像を２本の平行線ではさんだとき、その平行線の間隔が最小となる粒子の幅を短軸径といい、一方、この平行線に直角な方向の２本の平行線で粒子をはさむときの距離を長軸径という。 The average particle diameter can be determined as follows. That is, the diameter (mm) is measured when the sphericity from the projected particle cross section of the spherical sand particles is 1, while the major axis diameter of the spherical sand particles randomly oriented when the sphericity is less than 1 ( mm) and minor axis diameter (mm) are measured to obtain (major axis diameter + minor axis diameter) / 2, and the average particle diameter is obtained by averaging the obtained values for any 100 spherical cast sand particles. (Mm). The major axis diameter and the minor axis diameter are defined as follows. When the particle is stabilized on a plane and the projected image of the particle on the plane is sandwiched between two parallel lines, the width of the particle that minimizes the distance between the parallel lines is called the minor axis diameter. The distance when a particle is sandwiched between two parallel lines in a direction perpendicular to the line is called the major axis diameter.

なお、球状鋳物砂粒子の長軸径と短軸径は、光学顕微鏡またはデジタルスコープ（例えば、キーエンス社製、ＶＨ−８０００型）により該粒子の像（写真）を得、得られた像を画像解析することにより求めることができる。また、球形度は、得られた像を画像解析することにより、該粒子の粒子投影断面の面積および該断面の周囲長を求め、次いで、〔粒子投影断面の面積（ｍｍ²）と同じ面積の真円の円周長（ｍｍ）〕／〔粒子投影断面の周囲長（ｍｍ）〕を計算し、任意の５０個の球状鋳物砂粒子につき、それぞれ得られた値を平均して求める。 In addition, the major axis diameter and minor axis diameter of the spherical casting sand particles are obtained by obtaining an image (photograph) of the particles with an optical microscope or a digital scope (for example, VH-8000 type, manufactured by Keyence Corporation). It can be obtained by analysis. The sphericity is obtained by image analysis of the obtained image to determine the area of the particle projection cross section of the particle and the perimeter of the cross section, and then [the area of the same area as the area of the particle projection cross section (mm ² )] The circumference of the perfect circle (mm)] / [perimeter of the particle projection cross section (mm)] is calculated, and the obtained values are averaged for any of 50 spheroidal molding sand particles.

本発明の第１の態様の球状鋳物砂は火炎溶融法により得られるものである。従って、球形度が高く、緻密であるという構造的特徴を有する。当該構造的特徴は、流動性、鋳型強度、鋳造された鋳物の表面平滑性の向上に大きく寄与する。 The spherical foundry sand according to the first aspect of the present invention is obtained by a flame melting method. Therefore, it has a structural feature of high sphericity and denseness. The structural feature greatly contributes to improvement of fluidity, mold strength, and surface smoothness of a cast product.

本発明の第１の態様の球状鋳物砂としては、流動性の向上の観点から、その球形度が、０．９５以上であるものが好ましく、０．９８以上であるものがより好ましく、０．９９以上であるものがさらに好ましい。よって、本発明の第１の態様の球状鋳物砂としては、たとえば、Ａｌ₂Ｏ₃およびＳｉＯ₂を主成分として含有してなり、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１〜１５、平均粒径が０．０５〜０．５ｍｍ、球形度が０．９５以上である火炎溶融法でつくられた球状鋳物砂が好適である。 From the viewpoint of improving fluidity, the spherical casting sand of the first embodiment of the present invention preferably has a sphericity of 0.95 or more, more preferably 0.98 or more, and What is 99 or more is more preferable. Therefore, the spherical casting sand according to the first aspect of the present invention contains, for example, Al ₂ O ₃ and SiO ₂ as main components, and has an Al ₂ O ₃ / SiO ₂ weight ratio of 1 to 15, average grains. Spherical casting sand made by a flame melting method having a diameter of 0.05 to 0.5 mm and a sphericity of 0.95 or more is preferred.

一方、本発明の第２の態様の球状鋳物砂の球形度は０．９５以上である。流動性の向上の観点から、０．９８以上が好ましく、０．９９以上がより好ましい。 On the other hand, the sphericity of the spherical casting sand of the second aspect of the present invention is 0.95 or more. From the viewpoint of improving fluidity, 0.98 or more is preferable, and 0.99 or more is more preferable.

また、本発明の球状鋳物砂の吸水率（重量％）としては、鋳型の製造の際に使用するバインダーの鋳物砂内部への吸収によるバインダー使用量の増加の抑制や、鋳型強度の向上等の観点から、３重量％以下が好ましく、０．８重量％以下がより好ましく、０．３重量％以下がさらに好ましい。吸水率はＪＩＳＡ１１０９細骨材の吸水率測定方法に従って測定することができる。 In addition, the water absorption rate (% by weight) of the spherical casting sand of the present invention includes suppression of an increase in the amount of binder used due to absorption of the binder used in the production of the mold into the casting sand, improvement of the mold strength, etc. From the viewpoint, it is preferably 3% by weight or less, more preferably 0.8% by weight or less, and further preferably 0.3% by weight or less. The water absorption can be measured according to the method for measuring the water absorption of JIS A1109 fine aggregate.

なお、球状鋳物砂の吸水率は、火炎溶融法により該砂を調製した場合、該方法以外の焼成方法により調製した砂と比べて、同じ球形度であれば、通常、吸水率は低くなる。 In addition, the water absorption rate of spherical cast sand is usually lower when the sand is prepared by a flame melting method and the same sphericity as compared with sand prepared by a firing method other than the method.

一方、本発明の球状鋳物砂の球形度が０．９８以上である場合、かかる球状鋳物砂が、珪砂等の流動性の低い公知の鋳物砂との混合物中に好ましくは５０体積％以上含有されておれば、該混合物からなる鋳物砂は充分に本発明の所望の効果を発揮し得る。すなわち、前記のような公知の鋳物砂に本発明の球状鋳物砂を徐々に添加していけば、添加量に応じて本発明の所望の効果を発揮するようになるが、前記混合物からなる鋳物砂中に、前記所定の球形度を有する本発明の球状鋳物砂が５０体積％以上含まれると、その効果は顕著になる。なお、当該混合物からなる鋳物砂中の、球形度が０．９８以上である本発明の球状鋳物砂の含有量としては、より好ましくは６０体積％以上、さらに好ましくは８０体積％以上である。従って、本発明の球状鋳物砂としては、その利用性に優れることから、球形度が０．９８以上であるものが特に好適である。また、かかる球状鋳物砂を５０体積％以上含む鋳物砂は、本発明の球状鋳物砂と同等の効果を発揮し得ることから、かかる鋳物砂も本発明に包含される。 On the other hand, when the sphericity of the spherical casting sand of the present invention is 0.98 or more, the spherical casting sand is preferably contained in a mixture with a known casting sand having low fluidity such as silica sand in an amount of 50% by volume or more. In this case, the foundry sand made of the mixture can sufficiently exhibit the desired effect of the present invention. That is, if the spherical foundry sand of the present invention is gradually added to the known foundry sand as described above, the desired effect of the present invention will be exhibited depending on the amount added, but the cast comprising the above mixture. The effect becomes remarkable when 50% by volume or more of the spherical cast sand of the present invention having the predetermined sphericity is contained in the sand. In addition, as content of the spherical foundry sand of this invention whose sphericity is 0.98 or more in the foundry sand which consists of the said mixture, More preferably, it is 60 volume% or more, More preferably, it is 80 volume% or more. Accordingly, as the spherical casting sand of the present invention, one having a sphericity of 0.98 or more is particularly suitable because of its excellent utility. Further, since the foundry sand containing 50% by volume or more of the spherical foundry sand can exhibit the same effect as the spherical foundry sand of the present invention, such foundry sand is also included in the present invention.

前記の通り、本発明の第１の態様の球状鋳物砂は火炎溶融法により製造される。一方、本発明の第２の態様の球状鋳物砂は、たとえば、造粒して焼結する方法、電融アトマイズ法等の公知の方法により製造することが可能であるが、中でも、本発明の第１の態様の球状鋳物砂と同様に火炎溶融法により製造するのが好適である。そこで、以下においては、火炎溶融法による、本発明の球状鋳物砂の製造方法の一例を説明する。なお、当該製造方法も本発明に包含される。 As described above, the spherical foundry sand according to the first aspect of the present invention is manufactured by the flame melting method. On the other hand, the spherical foundry sand according to the second aspect of the present invention can be produced by a known method such as a method of granulating and sintering, an electromelting atomizing method, etc. It is preferable to manufacture by the flame melting method similarly to the spherical casting sand of the first aspect. Therefore, in the following, an example of a method for producing the spherical casting sand of the present invention by the flame melting method will be described. The manufacturing method is also included in the present invention.

本発明の球状鋳物砂の製造方法は、Ａｌ₂Ｏ₃およびＳｉＯ₂を主成分とする、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が０．９〜１７、平均粒径が０．０５〜２ｍｍの粉末粒子を出発原料とし、当該粉末粒子を火炎中で溶融して球状化する工程を含むものである。 Method for producing a spherical molding sand of the present invention is mainly composed of Al ₂ O ₃ and _{_{_{SiO 2, Al 2 O 3 /}}} SiO 2 weight ratio is from 0.9 to 17, an average particle diameter of 0.05~2mm The method includes a step of using powder particles as a starting material, and melting and spheroidizing the powder particles in a flame.

なお、ここで「Ａｌ₂Ｏ₃およびＳｉＯ₂を主成分とする」とは、出発原料としての粉末粒子全体における全成分中にＡｌ₂Ｏ₃およびＳｉＯ₂が合計量で８０重量％以上含有されていることをいう。よって、「Ａｌ₂Ｏ₃およびＳｉＯ₂を主成分とする」限り、当該粉末粒子としては、後述するようなＡｌ₂Ｏ₃源としての原料とＳｉＯ₂源としての原料の混合物からなるものであっても、（Ａｌ₂Ｏ₃＋ＳｉＯ₂）源としての原料単独からなるものであっても、また、Ａｌ₂Ｏ₃源としての原料および／またはＳｉＯ₂源としての原料と（Ａｌ₂Ｏ₃＋ＳｉＯ₂）源としての原料との混合物であってもよい。 Here, “having Al ₂ O ₃ and SiO ₂ as main components” means that Al ₂ O ₃ and SiO ₂ are contained in a total amount of 80% by weight or more in all components in the powder particles as a starting material. It means that Therefore, as long as “mainly composed of Al ₂ O ₃ and SiO ₂ ”, the powder particle is composed of a mixture of a raw material as an Al ₂ O ₃ source and a raw material as a SiO ₂ source as described later. Even if it consists of the raw material alone as the (Al ₂ O ₃ + SiO ₂ ) source, the raw material as the Al ₂ O ₃ source and / or the raw material as the SiO ₂ source and (Al ₂ O ₃ + SiO ₂₎ ₂ ) It may be a mixture with raw materials as a source.

出発原料としての前記粉末粒子においては、主成分であるＡｌ₂Ｏ₃およびＳｉＯ₂の合計量としての含有量は、得られる球状鋳物砂中のＡｌ₂Ｏ₃およびＳｉＯ₂の合計量が全成分中８０重量％以上になるようにする観点から、好ましくは７５重量％以上であり、より好ましくは８０重量％以上であり、さらに好ましくは８５〜１００重量％、特に好ましくは９０〜１００重量％である。Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率としては、得られる球状鋳物砂中のＡｌ₂Ｏ₃／ＳｉＯ₂重量比率が１〜１５になるようにする観点から、０．９〜１７であり、好ましくは１〜１５である。平均粒径としては、単分散の球状鋳物砂を得る観点から０．０５ｍｍ以上であり、所望の球形度を有する鋳物砂を得る観点から２ｍｍ以下であり、それらの両観点を満たすため０．０５〜２ｍｍである。また、得られる鋳物砂の球形度の向上という観点からは、０．０５〜１．５ｍｍが好ましい。 In the powder particles as the starting material, the content of the total amount of Al ₂ O ₃ and SiO ₂ as the main component, the total amount of Al ₂ O ₃ and SiO ₂ in the spherical molding in sand obtained all components From the viewpoint of making it 80% by weight or more, it is preferably 75% by weight or more, more preferably 80% by weight or more, still more preferably 85 to 100% by weight, particularly preferably 90 to 100% by weight. is there. The Al ₂ O ₃ / SiO ₂ weight ratio, from the viewpoint of Al ₂ O ₃ / SiO ₂ weight ratio of the spherical molding in sand obtained is made to be 1 to 15, it is 0.9 to 17, preferably 1-15. The average particle size is 0.05 mm or more from the viewpoint of obtaining monodispersed spherical casting sand, and is 2 mm or less from the viewpoint of obtaining casting sand having a desired sphericity. ~ 2mm. Moreover, from a viewpoint of the improvement of the sphericity of the obtained foundry sand, 0.05-1.5 mm is preferable.

Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が、原料粉末粒子と得られる球状鋳物砂とで異なるのは、原料によってＡｌ₂Ｏ₃の逸失量とＳｉＯ₂の逸失量とが異なるためである。また、原料粉末粒子の平均粒径については、不定型の粉末は球状になることで粒径が減少するが、もともと球状の粉末は粒径が変化しないので、上記範囲であればよい。 The reason why the Al ₂ O ₃ / SiO ₂ weight ratio differs between the raw material powder particles and the obtained spherical casting sand is that the amount of Al ₂ O ₃ lost and the amount of SiO ₂ lost differ depending on the raw material. The average particle size of the raw material powder particles may be in the above-mentioned range because the amorphous powder has a spherical shape and the particle size is reduced.

本発明の球状鋳物砂を得るためには、出発原料としての粉末粒子は、溶融時の成分蒸発を考慮し、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率および平均粒径が上記範囲内になるよう調製して使用する。 In order to obtain the spherical casting sand of the present invention, the powder particles as the starting material are prepared so that the component ratio of Al ₂ O ₃ / SiO ₂ and the average particle diameter are within the above ranges in consideration of component evaporation during melting. And use it.

出発原料である粉末粒子を溶融する際、当該粒子に水分が含まれると、該水分が蒸発するため、得られる鋳物砂には当該水分の蒸発に伴って多数の開孔が形成されることになる。当該開孔の形成は、鋳物砂の吸水率の増加や、球形度の低下をもたらす。従って、出発原料の含水率（重量％）としては、得られる球状鋳物砂の吸水率および球形度を適切な範囲に調節する観点から、１０重量％以下が好ましく、３重量％以下がより好ましく、１重量％以下がさらに好ましい。含水率は粉末粒子１０ｇを８００℃で１時間加熱した時の減量により測定する。 When melting the powder particles that are the starting material, if the particles contain moisture, the moisture evaporates, so that a large number of holes are formed in the resulting casting sand as the moisture evaporates. Become. The formation of the apertures results in an increase in water absorption rate of casting sand and a decrease in sphericity. Therefore, the water content (% by weight) of the starting material is preferably 10% by weight or less, more preferably 3% by weight or less, from the viewpoint of adjusting the water absorption and sphericity of the resulting spherical casting sand to an appropriate range. 1% by weight or less is more preferable. The water content is measured by weight loss when 10 g of powder particles are heated at 800 ° C. for 1 hour.

出発原料は、たとえば、耐火性を有する鉱産原料および合成原料から選ぶことができる。Ａｌ₂Ｏ₃源としての原料として、ボーキサイト、バン土頁岩、酸化アルミニウム、水酸化アルミニウム等を挙げることができる。また、ＳｉＯ₂源としての原料として、珪石、珪砂、石英、クリストバライト、非晶質シリカ、長石、パイロフィライト等を挙げることができる。また、（Ａｌ₂Ｏ₃＋ＳｉＯ₂）源としての原料として、カオリン、バン土頁岩、ボーキサイト、雲母、シリマナイト、アンダルサイト、ムライト、ゼオライト、モンモリロナイト、ハイロサイト等を挙げることができる。これらの原料はそれぞれ単独で、もしくは２種以上を混合して使用することができる。選択された出発原料は、その含水率を低下させるため、あるいはその溶融を容易にするために仮焼して使用するのが好ましい。仮焼された原料粉末粒子としては、仮焼バン頁、仮焼ムライト、仮焼ボーキサイト、仮焼した水酸化アルミニウムとカオリンとの混合物等が例示される。 The starting material can be selected from, for example, mineral raw materials and synthetic raw materials having fire resistance. Examples of the raw material as the Al ₂ O ₃ source include bauxite, van earth shale, aluminum oxide, aluminum hydroxide and the like. Examples of the raw material as the SiO ₂ source include silica, silica sand, quartz, cristobalite, amorphous silica, feldspar, and pyrophyllite. Moreover, examples of the raw material as the (Al ₂ O ₃ + SiO ₂ ) source include kaolin, bangshale shale, bauxite, mica, sillimanite, andalusite, mullite, zeolite, montmorillonite, and hyrosite. These raw materials can be used alone or in admixture of two or more. The selected starting material is preferably used after calcining in order to reduce its moisture content or to facilitate its melting. Examples of the calcined raw material powder particles include calcined van pages, calcined mullite, calcined bauxite, a mixture of calcined aluminum hydroxide and kaolin, and the like.

出発原料としての粉末粒子を火炎中で溶融して球状化する工程では、上記のような出発原料を酸素等のキャリアガスに分散させ、火炎中に投入することによって溶融し、球状化を行う（火炎溶融法）。好適な態様においては、下記火炎中に、投入する。 In the step of melting and spheroidizing powder particles as a starting material in a flame, the starting material as described above is dispersed in a carrier gas such as oxygen and melted by being introduced into a flame, and spheroidized ( Flame melting method). In a preferred embodiment, it is introduced into the following flame.

用いる火炎はプロパン、ブタン、メタン、天然液化ガス、ＬＰＧ、重油、灯油、軽油、微粉炭等の燃料を酸素と燃焼させることによって発生させる。燃料の対酸素比は完全燃焼の観点から容量比で１．０１〜１．３が好ましい。高温の火炎を発生させる観点から、酸素・ガスバーナーが好適である。特にバーナーの構造は限定するものではないが、特開平７−４８１１８号公報、特開平１１−１３２４２１号公報、特開２０００−２０５５２３号公報または特開２０００−３４６３１８号公報で開示されているバーナーが例示される。 The flame to be used is generated by burning fuel such as propane, butane, methane, natural liquefied gas, LPG, heavy oil, kerosene, light oil, pulverized coal and the like with oxygen. The fuel to oxygen ratio is preferably 1.01 to 1.3 in terms of volume ratio from the viewpoint of complete combustion. From the viewpoint of generating a high-temperature flame, an oxygen / gas burner is preferable. Although the structure of the burner is not particularly limited, the burners disclosed in JP-A-7-48118, JP-A-11-132421, JP-A-2000-205523, or JP-A-2000-346318 are disclosed. Illustrated.

本発明の製造方法で用いる０．０５〜２ｍｍの範囲にある大きな平均粒径をもつ上記耐火性の原料粉末を球状化するには以下の手法が好適である。 The following method is suitable for spheroidizing the above refractory raw material powder having a large average particle diameter in the range of 0.05 to 2 mm used in the production method of the present invention.

火炎中への粉末粒子の投入は、キャリアガス中に分散して行なう。キャリアガスとしては、酸素が好適に用いられる。この場合、キャリアガスの酸素は燃料燃焼用として消費できる利点がある。ガス中の粉体濃度は、粉末粒子の充分な分散性を確保する観点から、０．１〜２０ｋｇ／Ｎｍ^３が好ましく、０．２〜１０ｋｇ／Ｎｍ^３がより好ましい。 The powder particles are introduced into the flame by being dispersed in a carrier gas. As the carrier gas, oxygen is preferably used. In this case, there is an advantage that oxygen of the carrier gas can be consumed for fuel combustion. The concentration of the powder in the gas is preferably 0.1 to 20 kg / Nm ^{3 and} more preferably 0.2 to 10 kg / Nm ³ from the viewpoint of ensuring sufficient dispersibility of the powder particles.

さらに、火炎中に投入する際には、メッシュ、スタティックミキサー等を通過させて分散性を高めることがより好ましい。 Furthermore, when thrown into the flame, it is more preferable to pass through a mesh, a static mixer or the like to improve dispersibility.

火炎中での球状化を速やかに行なうと共に、単分散した球状鋳物砂を得る観点から、原料粉末粒子の形状と組成を選択することが好ましい。形状としては、火炎中での滞留時間確保や溶融、球状化を速やかに行なう観点から、原料粉末粒子の長軸径／短軸径比が９以下であるのが好ましく、より好ましくは４以下、さらに好ましくは２以下である。一方、組成としては、融着していない単分散の球状粒子を得る観点から、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１．５〜１０であるのが特に好適である。 From the viewpoint of promptly spheroidizing in a flame and obtaining monodispersed spherical casting sand, it is preferable to select the shape and composition of the raw material powder particles. As the shape, it is preferable that the ratio of the major axis diameter / minor axis diameter of the raw material powder particles is 9 or less, more preferably 4 or less, from the viewpoint of ensuring residence time in the flame, melting, and spheroidization quickly. More preferably, it is 2 or less. On the other hand, as the composition, from the viewpoint of obtaining monodispersed spherical particles that are not fused, it is particularly preferable that the Al ₂ O ₃ / SiO ₂ weight ratio is 1.5 to 10.

また、粉末粒子は、Ｎ₂不活性ガス等を電離させて生じるプラズマジェット火炎中でも好適に溶融し、球状化できる。 Further, the powder particles can be suitably melted and spheroidized even in a plasma jet flame generated by ionizing N ₂ inert gas or the like.

以上の方法により、本発明の所望の球状鋳物砂を得ることができる。当該鋳物砂は、流動性に非常に優れたものである。また、前記の通り、本発明の球状鋳物砂が所定の割合で含まれるように、該鋳物砂と公知の鋳物砂とを適宜混合することにより、本発明の球状鋳物砂と同等の効果を発揮し得る鋳物砂を得ることができる。鋳型の製造においてこれらの鋳物砂を用いると、使用するバインダーの量を少なくできることから、それらの鋳物砂は、鋳物砂として効率的に再生することができる。 By the above method, the desired spherical casting sand of the present invention can be obtained. The foundry sand is very excellent in fluidity. In addition, as described above, the casting sand of the present invention and the known casting sand are appropriately mixed so as to include the spherical casting sand of the present invention at a predetermined ratio, thereby exhibiting the same effect as the spherical casting sand of the present invention. Casting sand can be obtained. When these foundry sands are used in the production of a mold, the amount of binder used can be reduced, and therefore these foundry sands can be efficiently regenerated as foundry sand.

本発明の球状鋳物砂および該鋳物砂と公知の鋳物砂との混合物からなる鋳物砂（以下、これらの鋳物砂を本発明の鋳物砂と略記する）は、鋳鋼、鋳鉄、アルミニウム、銅およびこれらの合金等の鋳型用途に好適に使用されうる。また、金属、プラスチック等への充填材としても使用することができる。 Foundry sand of the present invention and a cast sand composed of a mixture of the foundry sand and a known foundry sand (hereinafter these cast sands are abbreviated as the foundry sand of the present invention) are cast steel, cast iron, aluminum, copper, and these It can be suitably used for mold applications such as alloys. It can also be used as a filler for metals, plastics and the like.

本発明の鋳物砂は、単独で、もしくは珪砂等のその他の公知の鋳物砂や耐火性骨材と組み合わせて、粘土、水ガラス、シリカゾル等の無機質バインダー、またはフラン樹脂、フェノール樹脂、フランフェノール樹脂等の有機質バインダーと混合され、所望の鋳造用鋳型を用いて公知の方法に従って造型され得る。高強度の鋳造用鋳型を得る観点から、バインダーの使用量としては、鋳物砂１００重量部に対して、バインダーを０．０５〜５重量部使用するのが好適である。このようにして得られる鋳型は、高強度であり、しかもその表面が平滑である。従って、この鋳造用鋳型で鋳造すると、表面荒れが小さく、後工程である研磨工程への負荷が小さい鋳物が得られる。 The foundry sand of the present invention can be used alone or in combination with other known foundry sand such as silica sand and fireproof aggregates, inorganic binders such as clay, water glass, silica sol, or furan resin, phenol resin, furan phenol resin. It can be mixed with an organic binder such as, and molded according to a known method using a desired casting mold. From the viewpoint of obtaining a high-strength casting mold, it is preferable that the binder is used in an amount of 0.05 to 5 parts by weight with respect to 100 parts by weight of foundry sand. The mold thus obtained has a high strength and a smooth surface. Therefore, when casting with this casting mold, it is possible to obtain a casting with a small surface roughness and a small load on the polishing step which is a subsequent step.

鋳造用鋳型の製造に使用する観点から、本発明の鋳物砂の粒子密度（ｇ／ｃｍ³）としては、１〜３．５ｇ／ｃｍ³の範囲であるのが好ましい。より高強度の鋳型を所望する場合、該粒子密度としては２．５〜３．５ｇ／ｃｍ³の範囲であるのが好ましい。この範囲のものは中実で緻密であり高強度の鋳型が得られる。また、軽量な鋳型を所望する場合、該粒子密度としては１〜２．５ｇ／ｃｍ³の範囲であるのが好ましい。この範囲のものは内部に空間を有する多孔質であり軽量な鋳型が得られる。粒子密度は、ＪＩＳＲ１６２０の粒子密度測定法に従って測定することができる。 From the viewpoint of use in the manufacture of the casting mold, the particle density of the molding sand of the present invention (g / cm ^3), it is preferably in the range of 1~3.5g / cm ^3. When a higher-strength mold is desired, the particle density is preferably in the range of 2.5 to 3.5 g / cm ³ . Those in this range are solid and dense, and a high-strength mold can be obtained. When a lightweight mold is desired, the particle density is preferably in the range of 1 to 2.5 g / cm ³ . The thing of this range is a porous which has a space inside, and a lightweight casting_mold | template is obtained. The particle density can be measured according to the particle density measuring method of JIS R1620.

また、前記鋳物をさらに適宜加工することにより、表面および内面欠陥の少ない構造物が得られる。当該構造物としては、たとえば、金型、エンジン部材、工作機械部材、建築部材等が挙げられる。 Moreover, a structure with few surface and inner surface defects can be obtained by further appropriately processing the casting. Examples of the structure include a mold, an engine member, a machine tool member, and a building member.

以上のような、優れた性質を有する鋳造用鋳型、鋳物および構造物は、本発明に包含される。 Casting molds, castings and structures having excellent properties as described above are included in the present invention.

実施例１
Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９７重量％含有する、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１．７、含水率が０重量％、平均粒径が０．３１ｍｍ、長軸径／短軸径比が１．５、のムライト粉末（柴田セラミックス製合成ムライト粉末）を出発原料とし、当該粉末を、酸素をキャリアガスとして用い、ＬＰＧ（プロパンガス）を対酸素比（容量比）１．１で燃焼させた火炎（約２０００℃）中に投入し、単分散した球状鋳物砂を得た。得られた鋳物砂は、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９７重量％含有しており、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１．７、平均粒径が０．２６ｍｍ、球形度が０．９９、吸水率が０重量％、粒子密度が２．９ｇ／ｃｍ³であった。該鋳物砂の反射顕微鏡（（株）ニコン製）写真（倍率：１００倍）を図１に示す。当該図より、いずれの鋳物砂粒子も球状であることが分かる。 Example 1
97% by weight of Al ₂ O ₃ and SiO ₂ in total, Al ₂ O ₃ / SiO ₂ weight ratio is 1.7, water content is 0% by weight, average particle size is 0.31 mm, major axis diameter / A mullite powder (synthetic mullite powder manufactured by Shibata Ceramics) having a minor axis diameter ratio of 1.5 is used as a starting material, the powder is used as a carrier gas, and LPG (propane gas) is used in an oxygen ratio (volume ratio) of 1 Was put into a flame (about 2000 ° C.) burned in 1. to obtain monodispersed spherical casting sand. The obtained foundry sand contains 97% by weight of Al ₂ O ₃ and SiO ₂ in total amount, the Al ₂ O ₃ / SiO ₂ weight ratio is 1.7, the average particle size is 0.26 mm, and the sphericity Was 0.99, the water absorption was 0% by weight, and the particle density was 2.9 g / cm ³ . A reflection microscope (Nikon Corporation) photograph (magnification: 100 times) of the foundry sand is shown in FIG. From the figure, it can be seen that all the foundry sand particles are spherical.

実施例２
出発原料の平均粒径を０．９ｍｍ、長軸径／短軸径比を１．７とした以外は実施例１と同様な操作で単分散した球状鋳物砂を得た。得られた鋳物砂は、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９７重量％含有しており、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１．７、平均粒径が０．６９ｍｍ、球形度が０．９７、吸水率が０重量％、粒子密度が２．８ｇ／ｃｍ³であった。 Example 2
Monodispersed spherical casting sand was obtained in the same manner as in Example 1 except that the starting material had an average particle size of 0.9 mm and a major axis / minor axis ratio of 1.7. The obtained foundry sand contains 97% by weight of Al ₂ O ₃ and SiO ₂ in a total amount, the Al ₂ O ₃ / SiO ₂ weight ratio is 1.7, the average particle size is 0.69 mm, and the sphericity Was 0.97, the water absorption was 0% by weight, and the particle density was 2.8 g / cm ³ .

実施例３
Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９７重量％含有する、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が２．７、含水率が０．１重量％、平均粒径が０．２５ｍｍ、長軸径／短軸径比が１．３のムライト粉末（柴田セラミックス製合成ムライト粉末）を出発原料とした以外は、実施例１と同様な操作で単分散した球状鋳物砂を得た。得られた鋳物砂は、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９８重量％含有しており、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が２．７、平均粒径が０．２１ｍｍ、球形度が０．９９、吸水率が０重量％、粒子密度が３．１ｇ／ｃｍ³であった。 Example 3
97% by weight of Al ₂ O ₃ and SiO ₂ in total, Al ₂ O ₃ / SiO ₂ weight ratio of 2.7, moisture content of 0.1% by weight, average particle size of 0.25 mm, long axis Monodispersed spherical casting sand was obtained in the same manner as in Example 1 except that mullite powder having a diameter / short axis ratio of 1.3 (synthetic mullite powder made by Shibata Ceramics) was used as a starting material. The obtained foundry sand contains Al ₂ O ₃ and SiO ₂ in a total amount of 98% by weight, the Al ₂ O ₃ / SiO ₂ weight ratio is 2.7, the average particle size is 0.21 mm, and the sphericity Was 0.99, the water absorption was 0% by weight, and the particle density was 3.1 g / cm ³ .

実施例４
Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９５重量％含有する、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１．６４、含水率０．２重量％、平均粒径が０．４５ｍｍ、長軸径／短軸径比が１．６のシリマナイトサンドを出発原料とした以外は、実施例１と同様な操作で単分散した球状鋳物砂を得た。得られた鋳物砂は、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９５重量％含有しており、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１．６、平均粒径が０．３５ｍｍ、球形度が０．９８、吸水率が０重量％、粒子密度が２．８ｇ／ｃｍ³であった。 Example 4
Containing 95% by weight of Al ₂ O ₃ and SiO ₂ , Al ₂ O ₃ / SiO ₂ weight ratio is 1.64, water content is 0.2% by weight, average particle diameter is 0.45 mm, major axis diameter A monodispersed spheroidal casting sand was obtained in the same manner as in Example 1 except that sillimanite sand having a minor axis diameter ratio of 1.6 was used as a starting material. The obtained foundry sand contains 95% by weight of Al ₂ O ₃ and SiO ₂ in a total amount, the Al ₂ O ₃ / SiO ₂ weight ratio is 1.6, the average particle size is 0.35 mm, and the sphericity Was 0.98, the water absorption was 0% by weight, and the particle density was 2.8 g / cm ³ .

実施例５
Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が２．５となるよう水酸化アルミニウムとカオリンを混合したものを電気炉にて７００℃で１時間仮焼し、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９６重量％含有する、含水率１．９重量％、平均粒径が０．２ｍｍ、長軸径／短軸径比が１．８の粉末粒子を出発原料とした以外は、実施例１と同様な操作で単分散した球状鋳物砂を得た。得られた鋳物砂は、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９５重量％含有しており、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が２．６、平均粒径が０．１９ｍｍ、球形度が０．９７、吸水率が０．１重量％、粒子密度が２．７ｇ／ｃｍ³であった。 Example 5
A mixture of aluminum hydroxide and kaolin was calcined at 700 ° C. for 1 hour in an electric furnace so that the Al ₂ O ₃ / SiO ₂ weight ratio was 2.5, and the total amount of Al ₂ O ₃ and SiO ₂ was The same as in Example 1 except that powder particles containing 96% by weight, water content 1.9% by weight, average particle diameter 0.2 mm, and major axis / minor axis ratio 1.8 were used as starting materials. By simple operation, a monodispersed spheroidal sand was obtained. The obtained foundry sand contains 95% by weight of Al ₂ O ₃ and SiO ₂ in total amount, the Al ₂ O ₃ / SiO ₂ weight ratio is 2.6, the average particle size is 0.19 mm, and the sphericity Was 0.97, the water absorption was 0.1 wt%, and the particle density was 2.7 g / cm ³ .

実施例６
Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９３重量％含有する、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１．５６、含水率０．１重量％、平均粒径が０．１５ｍｍ、長軸径／短軸径比が１．４の仮焼バン頁粉末を出発原料として実施例１と同様な操作で単分散した球状鋳物砂を得た。得られた鋳物砂は、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９３重量％含有しており、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が１．５５、Ｆｅ_２Ｏ_３含有量は１．７重量％、平均粒径が０．１４ｍｍ、球形度が０．９８８、吸水率が０重量％であった。 Example 6
Containing 93% by weight of Al ₂ O ₃ and SiO ₂ , Al ₂ O ₃ / SiO ₂ weight ratio of 1.56, moisture content of 0.1% by weight, average particle size of 0.15 mm, major axis diameter / Spherical casting sand monodispersed in the same manner as in Example 1 using calcined vane page powder having a minor axis diameter ratio of 1.4 as a starting material was obtained. The obtained foundry sand contains 93% by weight of Al ₂ O ₃ and SiO ₂ in a total amount, the Al ₂ O ₃ / SiO ₂ weight ratio is 1.55, and the Fe ₂ O ₃ content is 1.7. % By weight, average particle diameter was 0.14 mm, sphericity was 0.988, and water absorption was 0% by weight.

実施例７
Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９５重量％含有する、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が３．３６、含水率０．１重量％、平均粒径が０．１３ｍｍ、長軸径／短軸径比が１．２の仮焼バン頁粉末を出発原料として実施例１と同様な操作で単分散した球状鋳物砂を得た。得られた鋳物砂は、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９３重量％含有しており、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が３．３５、Ｆｅ_２Ｏ_３含有量は１．０１重量％、平均粒径が０．１２ｍｍ、球形度が０．９９８、吸水率が０重量％であった。 Example 7
Containing 95% by weight of Al ₂ O ₃ and SiO ₂ , Al ₂ O ₃ / SiO ₂ weight ratio is 3.36, water content is 0.1% by weight, average particle size is 0.13 mm, major axis diameter / Spherical casting sand monodispersed in the same manner as in Example 1 using a calcined vane page powder having a minor axis diameter ratio of 1.2 as a starting material. The obtained foundry sand contains 93% by weight of Al ₂ O ₃ and SiO ₂ in a total amount, the Al ₂ O ₃ / SiO ₂ weight ratio is 3.35, and the Fe ₂ O ₃ content is 1.01. The weight percentage was 0.12 mm, the sphericity was 0.998, and the water absorption was 0 wt%.

実施例８
Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９１重量％含有する、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が９．８３、含水率０．１重量％、平均粒径が０．１４ｍｍ、長軸径／短軸径比が１．３の仮焼バン頁粉末を出発原料として実施例１と同様な操作で単分散した球状鋳物砂を得た。得られた鋳物砂は、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９１．５重量％含有しており、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が９．３９、Ｆｅ_２Ｏ_３含有量は１．８７重量％、平均粒径が０．１３ｍｍ、球形度が０．９９６、吸水率が０重量％であった。 Example 8
Containing 91% by weight of Al ₂ O ₃ and SiO ₂ , Al ₂ O ₃ / SiO ₂ weight ratio is 9.83, moisture content is 0.1% by weight, average particle size is 0.14 mm, major axis diameter / Spherical casting sand monodispersed in the same manner as in Example 1 using a calcined vane page powder having a minor axis diameter ratio of 1.3 as a starting material. The obtained foundry sand contains 91.5% by weight of Al ₂ O ₃ and SiO ₂ in a total amount, the Al ₂ O ₃ / SiO ₂ weight ratio is 9.39, and the Fe ₂ O ₃ content is 1 It was 0.87% by weight, the average particle size was 0.13 mm, the sphericity was 0.996, and the water absorption was 0% by weight.

実施例９
Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９５重量％含有する、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が２．２１、含水率０重量％、平均粒径が０．１６ｍｍ、長軸径／短軸径比が１．４の仮焼ムライト粉末を出発原料として実施例１と同様な操作で単分散した球状鋳物砂を得た。得られた鋳物砂は、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９５．３重量％含有しており、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が２．１９、Ｆｅ_２Ｏ_３含有量は１．２１重量％、平均粒径が０．１３ｍｍ、球形度が０．９９５、吸水率が０重量％であった。 Example 9
Contains 95% by weight of Al ₂ O ₃ and SiO ₂ in total, Al ₂ O ₃ / SiO ₂ weight ratio is 2.21, moisture content is 0% by weight, average particle size is 0.16 mm, major axis diameter / short Using a calcined mullite powder having an axial diameter ratio of 1.4 as a starting material, monodispersed spherical casting sand was obtained in the same manner as in Example 1. The obtained foundry sand contains 95.3% by weight of Al ₂ O ₃ and SiO ₂ in a total amount, the Al ₂ O ₃ / SiO ₂ weight ratio is 2.19, and the Fe ₂ O ₃ content is 1 .21% by weight, the average particle size was 0.13 mm, the sphericity was 0.995, and the water absorption was 0% by weight.

比較例１
Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が２．７となるよう水酸化アルミニウムとカオリンを混合し、スプレードライヤーを用いて平均粒径０．２ｍｍの球状にした粉末粒子（Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９６重量％含有）を電気炉中にて１５００℃で１時間焼成することにより球状鋳物砂を得た。得られた鋳物砂は、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９７重量％含有しており、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が２．７、平均粒径が０．１８ｍｍ、球形度が０．８９、吸水率が１．２重量％、粒子密度が２．７ｇ／ｃｍ³であった。該鋳物砂の反射顕微鏡（（株）ニコン製）写真（倍率：１００倍）を図２に示す。当該図より、本鋳物砂粒子の形状は球状化率が低く、球形度が低いことが分かる。 Comparative Example 1
Powder particles (Al ₂ O ₃ and SiO ₂ having a mean particle diameter of 0.2 mm using a spray dryer, mixed with aluminum hydroxide and kaolin so that the weight ratio of Al ₂ O ₃ / SiO ₂ is 2.7. In a total amount) was fired at 1500 ° C. for 1 hour in an electric furnace to obtain spherical casting sand. The obtained foundry sand contains 97% by weight of Al ₂ O ₃ and SiO ₂ in a total amount, the Al ₂ O ₃ / SiO ₂ weight ratio is 2.7, the average particle size is 0.18 mm, and the sphericity Was 0.89, the water absorption was 1.2% by weight, and the particle density was 2.7 g / cm ³ . A reflection microscope (Nikon Corporation) photograph (magnification: 100 times) of the foundry sand is shown in FIG. From this figure, it can be seen that the shape of the foundry sand particles has a low spheroidization rate and low sphericity.

比較例２
Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が２５となるよう水酸化アルミニウムとカオリンを混合し、電気炉にて７００℃で1 時間仮焼して得た、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９７重量％含有する、含水率が２．９重量％、平均粒径が０．２ｍｍの粉末粒子を出発原料とした以外は、実施例１と同様な操作で球状鋳物砂を得た。得られた鋳物砂は、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９７重量％含有しており、Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が２６、平均粒径が０．１９ｍｍ、球形度が０．８８、吸水率が１重量％、粒子密度が３．３ｇ／ｃｍ³であった。 Comparative Example 2
Aluminum hydroxide and kaolin were mixed so that the Al ₂ O ₃ / SiO ₂ weight ratio was 25, and calcined at 700 ° C. for 1 hour in an electric furnace, and the total amount of Al ₂ O ₃ and SiO ₂ was obtained. Spherical foundry sand was obtained in the same manner as in Example 1 except that 97% by weight, water content of 2.9% by weight, and average particle diameter of 0.2 mm were used as starting materials. The obtained foundry sand contains 97% by weight of Al ₂ O ₃ and SiO ₂ in total amount, the Al ₂ O ₃ / SiO ₂ weight ratio is 26, the average particle size is 0.19 mm, and the sphericity is 0 The water absorption was 1% by weight, and the particle density was 3.3 g / cm ³ .

比較例３
Ａｌ₂Ｏ₃／ＳｉＯ₂重量比率が０．５となるよう珪石粉とカオリンを混合し、電気炉にて７００℃で１時間仮焼して得た、Ａｌ₂Ｏ₃とＳｉＯ₂を合計量で９７重量％含有する、含水率が０．９重量％、平均粒径が０．２ｍｍの粉末粒子を出発原料とした以外は、実施例１と同様な操作で鋳物砂を得た。ほとんどが不定形化し、球状のものはほとんど得られなかった。 Comparative Example 3
The total amount of Al ₂ O ₃ and SiO ₂ obtained by mixing silica powder and kaolin so that the Al ₂ O ₃ / SiO ₂ weight ratio is 0.5 and calcining at 700 ° C. for 1 hour in an electric furnace. Foundry sand was obtained in the same manner as in Example 1, except that powder particles containing 97% by weight, having a water content of 0.9% by weight and an average particle diameter of 0.2 mm were used as starting materials. Most of them became amorphous and almost no spherical shape was obtained.

比較例４
ＳｉＯ_２含有量９９重量％、平均粒径０．１３ｍｍの珪砂（不定形）を出発原料として実施例１と同様な操作で鋳物砂を得た。得られた鋳物砂は不定形なものであり、その吸水率は０．１重量％であった。 Comparative Example 4
Foundry sand was obtained in the same manner as in Example 1, using as a starting material silica sand having an SiO ₂ content of 99% by weight and an average particle size of 0.13 mm. The obtained foundry sand was irregular in shape, and its water absorption was 0.1% by weight.

試験例１
実施例１、３および５と比較例１〜２で得られた鋳物砂の流動性、ならびに当該鋳物砂から得られた鋳型の強度および表面肌の状態を調べた。 Test example 1
The fluidity of the foundry sand obtained in Examples 1, 3 and 5 and Comparative Examples 1 and 2, as well as the strength and surface texture of the mold obtained from the foundry sand were examined.

（１）鋳物砂の流動性
ＪＩＳＫ６７２１の漏斗を用い、流動時間（秒）をもとめた。流動時間が短いほうが流動性に優れる。 (1) Fluidity of foundry sand Using a funnel of JIS K6721, the flow time (seconds) was determined. The shorter the flow time, the better the fluidity.

（２）鋳型の強度
鋳物砂を７４〜２５０μｍに分級後、成形バインダーとしてカオーステップＳ６６０（花王クエーカー製）を鋳物砂１００重量部に対して１．２重量部添加し、自硬性鋳型造型法に従って成形（直径５０ｍｍ×高さ５０ｍｍ）し鋳型を得た。次いで、２４時間、室温で養生後、圧縮試験機を用い、鋳型の圧縮強度（ＭＰａ）を測定した（２５℃、湿度５５％）。 (2) Mold strength After classifying the foundry sand to 74 to 250 μm, add 1.2 parts by weight of Kao Step S660 (manufactured by Kao Quaker) as a molding binder to 100 parts by weight of the foundry sand, and follow the self-hardening mold molding method. Molding (diameter 50 mm × height 50 mm) was performed to obtain a mold. Next, after curing at room temperature for 24 hours, the compression strength (MPa) of the mold was measured using a compression tester (25 ° C., humidity 55%).

（３）鋳型の表面肌
以下の評価基準に従って鋳型から脱型後の鋳物表面を目視観察により評価し、当該評価結果を鋳型の表面肌の評価結果として用いた。すなわち、鋳物表面の状態が平滑であれば、鋳型の表面肌も平滑である。なお、鋳物は、鋳鉄ＦＣ−２５０を高周波炉により１４００℃で溶融し、５０ｍｍ×５０ｍｍ×４００ｍｍの直方体の形状のものを作製した。
〔評価基準〕
○: 鋳物砂跡がなく、平滑な面を示す
△: 鋳物砂跡が少し認められ、やや平滑な面を示す
×: 鋳物砂跡が明確で、荒れた面を示す (3) Mold surface skin The cast surface after demolding from the mold was evaluated by visual observation according to the following evaluation criteria, and the evaluation result was used as the mold surface skin evaluation result. That is, if the casting surface is smooth, the surface of the mold is also smooth. In addition, the cast iron melted cast iron FC-250 at 1400 degreeC with the high frequency furnace, and produced the thing of the shape of a rectangular parallelepiped of 50 mm x 50 mm x 400 mm.
〔Evaluation criteria〕
○: There is no casting sand mark and shows a smooth surface. △: Some casting sand marks are observed and the surface is slightly smooth. ×: The casting sand mark is clear and shows a rough surface.

以上の各試験結果を表１に示す。 The above test results are shown in Table 1.

表１に示す結果より、比較例１〜２の鋳物砂に比べ、実施例１、３および５の鋳物砂は優れた流動性を有することが分かる。また、得られた鋳型についても、比較例のものと比べ、実施例のものは強度に優れ、また、表面肌が平滑であることが分かる。実施例１、３および５の鋳物砂から製造された鋳型で鋳造された鋳物は後工程である研磨工程を充分軽減できる程に表面は平滑であった。 From the results shown in Table 1, it can be seen that the foundry sands of Examples 1, 3 and 5 have superior fluidity compared to the foundry sands of Comparative Examples 1 and 2. Also, it can be seen that the obtained molds are superior in strength and have a smooth surface skin as compared with the comparative examples. The castings cast with the molds produced from the foundry sands of Examples 1, 3 and 5 were smooth enough to reduce the subsequent polishing step.

試験例２
実施例９と比較例１、４で得られた鋳物砂を用い、バインダーをカオーライトナー３４ＯＢ（花王クエーカー製）とした以外は試験例１と同様にして鋳型の強度試験を０．５〜２４時間の経時で行なった。図３にそれらの鋳物砂から作製した鋳型の経時的な強度試験の結果を示す。該図に示すように実施例９の鋳物砂を用いた場合、短時間で鋳型強度が実用強度（２ＭＰａ程度）に達した。それゆえ、脱型が早く行なえ、作業効率が向上した。 Test example 2
The strength test of the mold was performed for 0.5 to 24 hours in the same manner as in Test Example 1 except that the foundry sand obtained in Example 9 and Comparative Examples 1 and 4 was used, and the binder was Kaolitener 34OB (manufactured by Kao Quaker). Was performed over time. FIG. 3 shows the results of strength tests over time of molds made from these foundry sands. As shown in the figure, when the foundry sand of Example 9 was used, the mold strength reached the practical strength (about 2 MPa) in a short time. Therefore, demolding can be performed quickly and work efficiency is improved.

また、実施例９と比較例１で得られた鋳物砂を用いて作製した鋳型の表面と、該鋳型を用いて作製した鋳物の表面の平滑性を表面粗さ測定器（小坂研究所製、サーフコーダＳＥ−３０Ｈ）により表面粗さ（中心線平均粗さ：Ｒａ）として測定した。Ｒａが小さい程、表面平滑性に優れる。結果を表２に示す。表２より、実施例９の鋳物砂を用いた場合、比較例１の鋳物砂を用いた場合と比べ、表面平滑性に優れた鋳型が得られ、それを用いて作製した鋳物の表面も平滑性に優れることが分かる。 Further, the surface roughness of the surface of the mold produced using the foundry sand obtained in Example 9 and Comparative Example 1 and the surface of the casting produced using the mold were measured with a surface roughness measuring instrument (manufactured by Kosaka Laboratory, Surface roughness (centerline average roughness: Ra) was measured with a Surfcoder SE-30H). The smaller the Ra, the better the surface smoothness. The results are shown in Table 2. From Table 2, when using the foundry sand of Example 9, compared to the case of using the foundry sand of Comparative Example 1, a mold having excellent surface smoothness was obtained, and the surface of the cast produced using the same was also smooth. It turns out that it is excellent in property.

試験例３
実施例３、９と比較例１、４で得られた鋳物砂について、鋳物砂の再生効率の指標となる耐粉砕性を比較した。各鋳物砂１ｋｇをアルミナボールミルにそれぞれ投入し、６０分間処理した後の平均粒径変化率〔（処理前の平均粒径／処理後の平均粒径）×１００〕を耐粉砕性の指標とした。該変化率が小さい程、耐粉砕性に優れる。結果を表３に示す。 Test example 3
The foundry sand obtained in Examples 3 and 9 and Comparative Examples 1 and 4 were compared in terms of pulverization resistance, which is an index of the foundry sand regeneration efficiency. 1 kg of each foundry sand was put into an alumina ball mill and the average particle size change rate [(average particle size before treatment / average particle size after treatment) × 100] after 60 minutes of treatment was used as an index of grinding resistance. . The smaller the rate of change, the better the pulverization resistance. The results are shown in Table 3.

表３より、実施例３と９の鋳物砂は、比較例１と４の鋳物砂に比べ、耐粉砕性に優れることが分かる。従って、使用するバインダーを少なくすることができ、使用後の砂中の残存炭素量が少なく、培焼再生が容易となる。培焼再生では粉化（摩耗粉になる）しないため、実施例３と９の鋳物砂は、再生効率に優れると言える。 From Table 3, it can be seen that the foundry sands of Examples 3 and 9 are superior in crush resistance as compared with the foundry sands of Comparative Examples 1 and 4. Therefore, the binder to be used can be reduced, the amount of carbon remaining in the sand after use is small, and the calcination regeneration is facilitated. Since it is not pulverized (becomes worn powder) in the calcination regeneration, it can be said that the foundry sands of Examples 3 and 9 are excellent in the regeneration efficiency.

試験例４
実施例３の鋳物砂５０体積％と比較例１の鋳物砂５０体積％とからなる鋳物砂、および実施例９の鋳物砂８０体積％と比較例４の鋳物砂２０体積％とからなる鋳物砂をそれぞれ得て、試験例１に準じて試験したところ、それらの鋳物砂は優れた流動性を有しており、また、該鋳物砂から得られた鋳型は、強度に優れ、表面肌が平滑であった。 Test example 4
Foundry sand consisting of 50% by volume of foundry sand in Example 3 and 50% by volume of foundry sand in Comparative Example 1, and foundry sand consisting of 80% by volume of foundry sand in Example 9 and 20% by volume of foundry sand in Comparative Example 4 When these were found and tested according to Test Example 1, the foundry sand had excellent fluidity, and the molds obtained from the foundry sand had excellent strength and smooth surface skin. Met.

以上の実施例が示すように本発明の球状鋳物砂は、鋳物砂に要求される諸特性に優れており、産業上有用である。 As shown in the above examples, the spherical foundry sand of the present invention is excellent in various properties required for foundry sand and is industrially useful.

図１は、実施例１で得られた鋳物砂の反射顕微鏡写真（倍率：１００倍）である。1 is a reflection micrograph (magnification: 100 times) of the foundry sand obtained in Example 1. FIG. 図２は、比較例１で得られた鋳物砂の反射顕微鏡写真（倍率：１００倍）である。FIG. 2 is a reflection micrograph (magnification: 100 times) of the foundry sand obtained in Comparative Example 1. 図３は、実施例９と比較例１、４で得られた鋳物砂からそれぞれ作製した鋳型の経時的な強度試験の結果を示すグラフである。FIG. 3 is a graph showing the results of strength tests over time for molds produced from the foundry sands obtained in Example 9 and Comparative Examples 1 and 4, respectively.

Claims

It was produced by a flame melting method comprising Al ₂ O ₃ and SiO ₂ as main components, having an Al ₂ O ₃ / SiO ₂ weight ratio of 1 to 15 and an average particle size of 0.05 to 1.5 mm. Spherical casting sand.

It contains Al ₂ O ₃ and SiO ₂ as main components, the Al ₂ O ₃ / SiO ₂ weight ratio is 1 to 15, the average particle size is 0.05 to 0.5 mm, and the sphericity is 0.95 or more. Spheroidal foundry sand produced by a flame melting method.

3. Spheroidal sand according to claim 1 or 2 , having a water absorption of 0.8% by weight or less.

Powder particles mainly composed of Al ₂ O ₃ and SiO ₂ and having an Al ₂ O ₃ / SiO ₂ weight ratio of 0.9 to 17 and an average particle diameter of 0.05 to 2 mm are melted in a flame to form a spherical shape. The manufacturing method of the spherical foundry sand in any one of Claims 1-3 including the process to convert.