JPH04371346A - Binder composition for sand core for high-pressure casting - Google Patents

Abstract

PURPOSE:To improve a collapsing property of the sand core and to eliminate the need for the execution of a heat treatment in a knock-out stage as well as to decrease the number of stages by using the above binder compsn. at the time of producing the sand core to be applied to an undercut part in die casting for casting a light alloy under a high pressure. CONSTITUTION:This binder compsn. for the sand core for high-pressure casting is the binder compsn. used at the time of producing the sand core to be applied to the undercut part in die casting for casting the light alloy under several 10 to several 100kg/cm<2> pressure by blowing gaseous or aerosol sulfur dioxide into a sand mold formed by adding and mixing the binder compsn. and peroxide compsn. to and with refractory aggregate and molding the mixture. The above- mentioned binder compsn. consists of at least one kind selected from specific groups or at least one kind of the copolymers thereof and at least one kind among a furan resin, phenol resin, urea resin, and melamine resin.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for use in manufacturing sand cores to be applied to undercut portions in die casting for casting light alloys under high pressure. More specifically, several 10 kg/cm2 to several 100
A sand core applied to the undercut part in die casting for casting light alloys at a pressure of kg/cm2 is molded into a sand mold made by adding and kneading a binder composition and a peroxide composition to refractory granular aggregate. The present invention relates to a binder composition for high-pressure casting sand cores, which is used when manufacturing by blowing gaseous or aerosol sulfur dioxide.

0002

[Prior art and problems to be solved by the invention] Conventionally,
When manufacturing a hollow product or an undercut product by pressure casting, the product is divided into parts, cast, and then assembled by welding or other construction methods. However, if a collapsible sand core can be used, it will be possible to integrally cast products with complex shapes, and improvements in casting quality and cost benefits can be expected. Salt cores are used as part of these collapsible sand cores, but salt cores are difficult to mold into cores with complex shapes, and furthermore, special molds and molding machines are required. Therefore, the cost is high, and a collapsible sand core is required as an alternative for energy saving and rationalization.

[0003] As a sand core molding process, the shell mold method is widely used, in which so-called resin coated sand, in which refractory granular aggregate is coated with phenol novolac resin, is molded and heat cured. It is undesirable because it has poor collapsibility and requires heat treatment to take out the sand mold in the disassembly process, which increases the number of processes. As a process with good disintegration, a sand core is manufactured by adding gaseous or aerosol sulfur dioxide into a sand mold made by adding and kneading acid-curable resin and peroxide composition to fire-resistant granular aggregate. There is a Franco cold box method that has been attracting attention recently.

0004

[Means for Solving the Problems] The present inventors have conducted intensive research to further improve the disintegrability of the Fran cold box method, which has good disintegration properties among high-speed mold making methods, and as a result, have completed the present invention. It is something that That is, the present invention can be applied to several 10 kg/cm2 to several 100 kg/cm2.
A sand core applied to the undercut part in die casting for casting light alloys at a pressure of
A binder composition used in production by blowing gaseous or aerosol sulfur dioxide, the binder composition comprising (1) the following (a) to (f) (a) ketone and aldehyde. (b) Polycondensate of aromatic hydrocarbon and aldehyde (c) Polycondensate of resorcin and aldehyde (d) Polycondensate of alkylresorcin and aldehyde (e) Oxirane in one molecule Epoxy resin containing two or more rings (f) A compound containing two or more vinyl groups or vinylidene groups in one molecule, which has at least one aromatic ring and further contains two or more acrylate groups, methacrylate groups, and allyl groups. (2) Furan resin, phenol resin,
The present invention relates to a binder composition for high-pressure casting sand cores, which is characterized by comprising at least one of a urea resin and a melamine resin.

The content of the above component (1) in the binder composition of the present invention is preferably 3 to 50% by weight, more preferably 5 to 30% by weight. In addition, the molecular weight range of the component (1) above is 100,000 or less, preferably 5,000 or less, and more preferably 1,000 or less, taking into account the viscosity of the binder composition, workability, etc. selected.

[0006] When the molecular weight range exceeds 100,000, the viscosity of the binder composition becomes high, resulting in a decrease in mold density and uneven filling of the mold, resulting in a decrease in mold strength and a large negative impact on mold formability. give. In the present invention, as a form in which the above two components are used together, the component (1) above may be separately added and mixed together with the component (2) in the refractory granular aggregate during mold manufacturing. The component (1) may be incorporated into the reaction system for producing the component (2), or may be mixed with the component (1) after the component (2) is produced. Furthermore, in the present invention, the following may be included in the binder composition as necessary.

[0007]

[Chemical formula 1]

(c) The substituent attached to the benzene ring is one or two or more of each of a methoxy group, an aldehyde group, or a nitro group, or two or more types including a hydroxyl group.
Aromatic compounds having more than one species or having two or more hydroxyl groups. (d) Aliphatic hydrocarbons having 5 to 12 carbon atoms. (e) Heterocyclic compounds having one or more oxygen atoms in a five- or six-membered ring, or compounds having one or more aldehyde groups in the furan ring. (f) Compound represented by the general formula R5-COO-R6 (R5 and R6 are aliphatic hydrocarbon groups having 18 or less carbon atoms, provided that one of them can be a hydrogen atom.)

[0009]

[Case 2]

(i) General formula R10-COO-R11
Compound represented by -OOC-R12 (R10 , R1
1 and R12 are aliphatic hydrocarbon groups having 6 or less carbon atoms). (j) General formula R13-COO-R14-O-R15
Compounds represented by (R13 , R14 and R15
is an aliphatic hydrocarbon group having 4 or less carbon atoms).

[0011]

[Chemical formula 3]

(l) Styrene resin or α-methylstyrene resin obtained by polymerizing styrene monomer or α-methylstyrene monomer. (m) A coumaron resin made by copolymerizing a mixture of coumaron, indene, and styrene. (n) Unsaturated polyester obtained by esterifying a dicarboxylic acid component mainly consisting of fumaric acid or maleic acid and an ethylene oxide or propylene oxide adduct of 2,2-bis(4'-oxyphenyl)propane 100 weight and 0 to 30 parts by weight of styrene. (o) Liquid polybutadiene resin or liquid polybutene resin obtained by polymerizing a butadiene monomer or a butane-butene monomer mixture. (p) Natural animal and vegetable oils and fats or natural resins. (q) Silane coupling agent.

Furthermore, a sand core is produced by adding and kneading the binder composition and peroxide composition of the present invention to the refractory granular aggregate, and then blowing gaseous or aerosol sulfur dioxide into a molded sand mold. When molding, it is possible to practically prepare the template by separately adding in advance a composition consisting of a resin component mainly consisting of at least one phenolic compound having a substituent that increases the charge density at the ortho or para position relative to the hydroxyl group. The initial strength of can be significantly improved. When producing a mold using the binder of the present invention, silica sand containing quartz as a main component, zircon sand, chromite sand, etc. are used as the refractory granular aggregate. As the oxidizing agent, it is preferable to use a peroxide composition containing a peroxide of an aliphatic ketone as a main component. Usually, 0.5 to 3 parts by weight of acid-curing resin and 0.1 to 1 part by weight of the above peroxide composition are added and kneaded to 100 parts by weight of fire-resistant granular aggregate, and molded into a sand mold. A method of manufacturing the mold by blowing gaseous or aerosolized sulfur dioxide is preferred.

The sand core produced using the binder of the present invention has a surface coated with conventionally known surface coating agents, such as refractories such as zircon flour, synthetic mica, and colloidal silica, as well as molasses and hentonite. Add binder ingredients such as water,
After applying and drying a surface coating agent mixed with lower alcohol to form a film, it is set in a mold and a light alloy is cast with a die-casting machine at a pressure of several tens of kg/cm2 to several hundred kg/cm2. .

[0015]

EXAMPLES The present invention will be explained in detail below with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 11 and Comparative Examples 1 to 2 Silica sand 10
A sand mixture prepared by adding and kneading 12 parts by weight of a urea-formalin-modified furan resin containing the substances according to the present invention listed in Table 1 and 5 parts by weight of methyl ethyl ketone peroxide to 00 parts by weight was mixed with 50 m/m φ x 50 m/m. After filling the cylindrical model, a mold was formed by passing SO2 gas for 1 second and pressurized air for 5 seconds. The cylindrical sand core of the shell is made of resin coated sand.
RCS) into a vertical split molding machine for shells at an air pressure of 1.5 kg/
cm 2 and baked at a curing temperature of 300° C. for 1 minute to form a mold. Zircon flower 7 in molded sand core
0 parts by weight, 20 parts by weight of synthetic mica, 10 parts by weight of colloidal silica
After applying and drying a surface coating agent consisting of 5 parts by weight of Hetonite, 2 parts by weight of molasses, and 40 parts by weight of water to form a film, it was set in a mold and heated to 100 kg/c.
Aluminum alloy (material AC-4C) at a pressure of m2
was cast using a die-casting machine, and the sand shakeout properties were evaluated. The results are shown in Table 1.

[0017]

[Table 1]

Core knock time to reach 90% disintegration rate 0
~20sec ○

20~40sec △

40sec or more ×

[0019]

Effects of the Invention: By using the binder composition of the present invention when manufacturing sand cores that are applied to undercut parts in die casting for casting light alloys under high pressure, the disintegrability of the sand cores can be improved. In addition, heat treatment in the dismantling step is unnecessary, and the number of steps can be reduced.

Claims (2)

[Claims] [Claim 1] Several 10 kg/cm2 to several 100 kg
A sand core applied to the undercut part in die casting for casting light alloys at a pressure of g/cm2 is molded into a sand mold made by adding and kneading a binder composition and a peroxide composition to refractory granular aggregate. A binder composition used when producing by blowing gaseous or aerosol sulfur dioxide,
The binder composition comprises (1) the following (a) to (f) (a) a polycondensate of a ketone and an aldehyde (b) a polycondensate of an aromatic hydrocarbon and an aldehyde (c) a resorcinol and an aldehyde (d) Polycondensate of alkylresorcinol and aldehyde (e) Epoxy resin containing two or more oxirane rings in one molecule (f) Containing two or more vinyl groups or vinylidene groups in one molecule At least one compound or at least one copolymer thereof, which has at least one aromatic ring and further has one or more of two or more acrylate groups, methacrylate groups, and allyl groups; (2) Furan. based resin, phenolic resin,
A binder composition for high-pressure casting sand cores, comprising at least one of a urea resin and a melamine resin. 2. The viscous material for high-pressure casting sand cores according to claim 1, wherein the content of at least one of (a) to (f) or at least one copolymer thereof (1) is 3 to 50% by weight. Binder composition.