SU685410A1 - Method of preparing plated sand for making shell moulds and cores - Google Patents

Description

The invention relates to foundry, in particular, to methods for preparing clad sands used in the manufacture of shell molds and cores, produced in a permanent modal core tooling.

The closest to the described invention to the technical essence and the achieved result is with a method of preparing a clad sand for making shell shells and rods, according to which the preheated sand is successively mixed with novolac resin with an aqueous solution of hexamethylene tetramine and wax-like dispersion 1. In this case water dispersion plays the role of a separating agent and contributes to the improvement of the quality of the shells and the very increase in the accuracy of castings,

However, to obtain acceptable strength properties of shell molds and cores using sand clad in a known manner, low costs of novolac resin (6-7% of the sand weight) are required, and the cladding process itself leads to increased energy costs. The purpose of the invention is to reduce the consumption of Novolac resin and reduce the power consumption during the plating process.

To achieve the goal in the preparation of clad sand

for making shell forms and cores, including preheating sand and mixing with it novolac resin, an aqueous solution of hexamethylenetetramine and water

The dispersion, water-wax dispersion is introduced into the sand and stirred before the introduction of the Novolac resin and an aqueous solution of hexamethylenetetramine. As a water-wax dispersion, it is preferable to use a technical product of the brands VVD-2M or VIS-13 (TU 38-40112-73). The wax concentration in the water-wax dispersion is 30-46%. The optimal consumption of water-wax dispersion is 0.025-1.0% of the weight of the sand to be plated. As a Novolac resin, commercially available SF-015 resin (GOST 18694-73) can be used. A preferred concentration of an aqueous solution of hexamethylenetetramine is 30-36%, e.g. 33%.

With a wax shell on the surface of sand grains, the wetting angle of sand with resin melt is reduced by 2 times, and the flow rate of resin increases by 1.5-2 times. This ensures that the resin is evenly distributed over the surface of the sand in the whole range of cladding temperatures. The temperature range of cladding sands treated with a water-wax dispersion is shifted by 20 ° C towards the low temperatures, i.e. cladding with the use of SF-015 resin can be performed at 110-130 0. At these

Content of ingredients,% by weight

Ingredients of the refractory filler to be plated, in blends №

The viscosity of the resin melt is considerable (60–350 Pz) and it is impossible to carry out the process of preparing high-quality mixtures using known technology.

The compositions of the mixtures for the manufacture of shell forms and cores obtained by the proposed (mixture No. 1-6) and known (mixture 7) methods are given in Table. one.

The cladding is carried out at. The curing of shell molds and cores is carried out at a heating temperature of snap 250s for 3 minutes.

Properties of mixtures 1-7 are given in table. 2

T. ablitsa

0.025 0.5

4.5 4.5

0.5 0.5 0.5 0.5 0.5 0.6 O, 5

37

40 36 35 44 39 39 4

13 15 3 11 14 5050 50 50 50 50 100 200 200 200 200 200 200 250

As follows from the table. 2, the proposed cladding method, in comparison with the known method, ensures an even distribution

0.1

0.03 0.5 1.0 4.5 4.5 4.5 4.5 6.0

table 2

resin on the surface of grains of sand, which allows to reduce its consumption by 25%, as well as reduce electricity consumption in the preparation of the plated mixture by about 15%. The magnitude of irregularities on the surface of the obtained castings does not change significantly, i.e. the quality of the castings remains as high as with the known cladding method.

Claims (1)

Invention Formula A method of preparing clad sand for making shell molds and cores, including preheating the sand to mix with it a novolac resin, an aqueous solution of hexamethylenetetramine and a water-wax dispersion, characterized in that, in order to reduce the consumption of novolac resin and reduce electricity consumption during the plating process, The water-wax dispersion is introduced into the sand and entangled before the introduction of the Novolac resin and the aqueous solution of hexamethylenetetramine. Sources of information taken into account in the examination It is the Copyright. According to the application 2166834 / 22-02, cl. B 22 C 1/22, 08.18.75.