SU582039A1 - Method of preparing coated sand for shell moulds and cores - Google Patents

Description

preparing clad sand for making foundry shell molds and cores, obtained by Yio permanent model and core equipment, including mixing sand with oxides of carbonates or with a combination of these additives, followed by plating the mixture with thermosetting powdered resin, characterized in that the additive and sand are heated by a mixture of thermosetting powder resin; resin separately before mixing.

Preliminary separate cladding of sand and an anti-defect additive with a resin binder eliminates direct contact of the anti-defect additive with the surface of quartz sand, which allows maintaining high surface sand activity in relation to the binder and thereby preventing a significant decrease in the strength properties of cladding sand shells.

The invention is illustrated by the following example.

For the preparation of clad sand, the following raw materials are used: quartz sands of the grades KO20A and KO20B of the Verkhnedpeprovsky and Lyubertsy deposits, known to Balaklavsky and iron ore from the Krivoi Rog deposits of 0.16 mm, thermosetting powdered resin PC-104, technical acetone and technical stearate calcium.

The consumption of resin PK-104 is 5 wt. %, acetone 1.8 wt. %, calcium stearate 0.1 weight. % (per 100 wt.% sand). The consumption of anti-defect calcium carbonate based additives (limestone) and iron oxide (iron ore) is indicated below.

Silica sand and anti-defect additives are plated separately with PC-104 resin: A known cold cladding method using acetone and calcium stearate.

The sequence of operation of the cladding process is as follows. Bulk materials (sand and powdered resin PK-104) are mixed for 1 minute. Acetone is then added and the mixture is stirred for 3 minutes. In this case, it is blown with compressed air for 10 minutes, after which the air is turned off, calcium stearate is introduced, and the mixture is stirred for 3 minutes.

Anti-defect additives are plated in the same way.

The clad sand is mixed with the plated anti-defect additive for 3-5 minutes.

The tensile strength of the clad mixtures was determined on specimens of eights 15 mm thick, cured in a core sheath heated to 270-280 ° C for 120 seconds.

The results of the strength tests are given in the table.

Note.

Thus, the method according to the invention is compared with

Claims (2)

in a known manner. Reduce the loss of npo4HoctM shell forms and sterols, the observed fluctuation of the values of the strength characteristics when using clad sands without additives is explained by a different type of quartz sand. 5 with the introduction of anti-defect additives, to a minimum, i.e., to achieve a predetermined increase in the physicomechanical characteristics. The invention of the method of preparation of clad sand for the manufacture of casting shell molds and cores, obtained by a constant model-core tooling, including ne-mixing sand with the addition of oxides or carbonates or with a combination of these additives, followed by plating the specified SS20 6 mixture of thermosetting powder resin , from l ii h and y w, and with the fact that, in order to increase the strength of shell forms and cores, the additive and sand are clad with a powdered thermosetting resin separately before their confusing. Sources of information taken into account in the examination 1. Prospect G. V. and others. Manufacturing of rods on a heated snap. M., “Engineering, 1970, p. 9. 2. Andrews P., P. Shell Molding Technique in the USA. M., “Mechanical Engineering, 1968, p. 79.