SU797834A1 - Composition for making shell moulds and cores - Google Patents

Description

one

The invention relates to foundry, namely, to mixtures for the manufacture of casting shell molds and core in constant models.

Clad mixtures for the preparation of shell forms and cores are known, containing a refractory filler, novolac or resole resin, hexamine, release agent 1.

However, shell molds and rods from this mixture have satisfactory strength characteristics only with an increased resin content, which leads to an increase in the gas-gas content of the mixture and its appreciation.

Closest to the described invention by its technical essence and the achieved result is a mixture based on clad sand for the formation of kidney-shaped forms and rods, containing a refractory filler, novolac resin, urotropin and a water-wax dispersion with a wax content in the latter 4146 wt.% 2 .

However, this mixture is characterized by a low rate of increase of the shell during its formation on the model equipment, which negatively affects the productivity of the process equipment.

The purpose of the invention is to increase the speed of hot curing shell molds and cores.

To achieve this goal, the mixture for the manufacture of casting shell molds and cores using a constant model-core tooling, including a refractory filament, novolac resin, aqueous 33% solution of urotropine and water-wax dispersion, additionally contains an additive selected from the group of dihydric alcohols or their derivatives (glycol, ethylene glycol, and ether; diethylene glycol). in the following ratio of ingredients, wt.%;

Novolacna resin

2.0-7.0 Aqueous 33% solution of urotro0, 6-2.1 pins of Water-wax

Dispersing 0.02-0.5

An additive selected from the group of the indicated dihydric alcohols or their derivatives, 0, 02-0.5 Refractory filler. The remaining increase in the rate of shell formation (hot curing of the shell) is due to the fact that when the mixture is heated glycol or alkyl ether glycol (alkyl ether, ethylene glycol or alkyl ether diethylene glycol) begin to boil, and the resulting gaseous products contribute to an increase in heat transfer in the shell due to convection. As glycols or alkyl esters of glycols can be used The compounds have a boiling point lower than the optimum shell formation temperature of 200-275 ° C.

The content of glycol or alkyl ether of ethylene glycol or alkyl ether of diethylene glycol should be within the specified limits, since if the content is more than 0.5, the peeling of the shell and the decrease in its strength begin to appear. When the content of this substance in the mixture is less than 0.02%, the rate of increase of the shell changes only slightly due to the small amount of gaseous boiling products.

The mixture is prepared as follows.

Heated to a temperature of 110,200 ° C, the refractory filler is mixed with novolac resin in an amount of 2-7 wt.%, Then water-wax dispersion with a concentration of solid wax of 3046 wt.% In an amount of 0.02-0.5 weight is introduced into the mixture, % then an additive selected from the group of glycol, diethyleneglycol alkyl ether in an amount of 0.020.5% by weight and a 33% aqueous solution of hexamine 0.6-2.1% by weight are added and stirring is continued until the finished coated mixture is obtained.

The introduction of additives of dihydric alcohols or their prod.vrdnyh) is possible together with a water-wax dispersion or with an aqueous solution of hexamine. In the case when water is used to cool the mixture before introducing an aqueous solution of hexamine, it is possible to add this additive together with water.

PRI me R. Prepare a mixture No. 1-11 proposed method and the mixture No. 12 in accordance with the known technical solution 2. The compositions of the mixtures are given in table. 1. The following compounds were used as glycols: ethylene glycol (GOST 10164-75), butanediol-1,4 (TU 6-09-6316-69). As alkyl ethers of glycols, ethylene glycol monoethyl ether (TU RTU 6-09-2906-66) and diethylene glycol monoethyl ether (TU 14P-739-68) are used. Properties of the mixtures are given in table. 2

The physicomechanical properties of the mixtures were evaluated on standard samples, which were manufactured and tested according to GOST 13507-68.

The rate of formation of the shells during their curing process was determined as follows.

In the frame, installed on a heated plate, covered with clad sand. After a certain time has elapsed, the frame with the mixture was removed and the uncured mixture was removed. After polymerization of the shell in the furnace, it was removed from the frame, cut and measured, or the thickness of the shell at six points.

As follows from the table. 2, mixtures containing the addition of ethylene glycol butanediol-1,4, ethylene glycol monoethyl ether or diethyl.phenglycol in an amount of 0.02-0.5% by weight of sand have an increased (up to 56%) shell formation rate as compared to conventional clad blends mi In the manufacture of shells with a thickness of 10 mm, their formation time decreases from 66 seconds to 29-38 seconds; Taking into account that the share of the formation operation is 40-50% of the total cycle of manufacturing rods, the increase in productivity in the manufacture of rods from the use of a new mixture will be up to 17-25%. The marked reduction in shell formation time means an increased rate of hot curing of the molds and cores. Name of Ingredients Noe-Olachna SF-015, GOST 18694-73 744-444 Novolachna SF-260, TU 6-05-231-114-75 --- 2 - Wave solution of urotropine 33% concentration 2.1 1.2 1 , 2 0.6 1.2 1.2 1, Water-wax dispersion VVD-2M TU 38-101676-77 0.020.13 0.5 -0.13 0.13 0.13 0, Ethylene glycol GOST 10164-75 0.020.15 0.1 0.5 1.0 0.01 Butandiol -1, 4 TU 6-09-6316-69 ------ Ethylene glycol mono ethylether MRTU 6-09 906-66 Diethylene glycol dimethyl ether TU 14P- 739 8 ---- Quartz sand About 016A GOST 21387490, 8694,6294.20 96.7-93.67 94.66

Table

0.5

Table 2 Number cm "si and orbital ingredients, wt.% -; iiij; i:; i ;:: i :: i; rii; : i: rL: i; :: i: EL 44444 .1, 2 1.2 1.2 1.2 1.2 0.1 0.13 0.13 0.13 0.13 0.13 - - - - 0.1 0.5 94.57 94, 17 94.62 94,5794.77 94.67

Strength of tensile specimens at 2G ° C, kgf / cm2 Strength of tensile specimens at, kgf / cm2 Shell thickness, mm, at a shell formation temperature of 250 ° C and holding time, from 15 30 45 60 TGPG 51.9 46, 0 45.9 25.1 35.7 46.1 46.8 47.9 45.0 46.2 45.945.1 35.6 29.6 29.0 14.7 23.6 28.3 29.3 28 , 7 28.1 28.9 29, 3 28.7 5.5 5.9 6.7 7.3 7.5 9.2 6.2 7.4 6.0 6.6 7.3 5.1 7.6 8.2 9.6 10.2 10.8 7.3 9.0 10.1 8.4 9.4 10.2 7.0 9.1 9.8 11.1 12.1 12, 7 8.7 10.5 11.8 9.9 11.0 11.9 8.4 9.9 10.4 12.4 14.2 14.8 9.5 11.2 13.7 10.6 12 , 2 13.5 9.3 e. The difference in physicomechanical properties of mixtures No. 1, 4 and mixtures No. 2, 3, 6-11 is explained by the different content of novolac resin. :

Claims (2)

1.Foundry, 1973, 101, No. 12, 5 p. 46-49. 2. USSR author's certificate number 532449, cl. B 22 C 1/22, 1975.