SU1252014A1 - Sand for making cores - Google Patents

Description

The invention relates to a foundry, in particular, to compositions of mixtures for the manufacture of cores, which are used primarily for the production of castings from aluminum alloys.

The aim of the invention is to improve the knock-out of the rods, and to improve the quality of the rods by increasing their dimensional accuracy during heating.

The essence of the invention is as follows.

In the proposed mixture, sodium chloride and graphitized powder correspond to GOST. The binder is a composition consisting of 80 May. % phenol formaldehyde resin powder, 15 May. Z urotropina and 5 us. % stearin.

The introduction of sodium chloride with a melting point, the grains of which are evenly distributed between the particles of graphitized powder, limits their adhesion during resin polymerization during annealing, contributes to the destruction of stubble during the washing process and subsequent from whitefish. This increases the density of the casting layer adjacent to the core, and also increases the dimensional accuracy of the core, which contributes to the production of high-quality castings with higher tightness requirements.

The introduction of potassium permanganate and the mixture promotes the combustion of the carbon of the mixture in an oxygen environment under temperature effects on the rod, which facilitates the degradability of the latter with sufficiently long-term high-temperature exposure.

Grafted powder 58,760,762,655.6 64.8

Fiolformaldegmdnoe

binder7 5 7 75

Sodium chloride 34343037 30

Potassium permanganate 0.3 0.30.40.4 0.2

The core mixture is prepared as follows.

A graphitized powder and sodium chloride are loaded into a roller-type mixer, phenol-formaldehyde resin-based binder is added and mixed for 2-3 minutes. Potassium permanganate is introduced into the mixture immediately before the manufacture of the rods and mixed in the same mixer for 30-60 seconds. From the prepared mixture by extrusion get. Casting rods.

The compositions of the proposed mixtures 1-5 are given in table. one.

Table 2 shows data on the breakability of rods from mixtures 1-5. The tests were carried out with castings obtained by pouring aluminum alloy AL-2 (pouring temperature 690-700 C) into a metal mold assembled with a rod from the tested mixtures. The destructibility of the rods was measured after a 2A-hour heat treatment of the castings at a temperature of 500 ° C by fixing the time for removing the rods when embossing the castings on a unified inertial-type knock out lattice.

In tab. 3 shows the comparative indicators of other technological and thermophysical properties for the proposed mixtures (summarized data for compounds 1-5).

It follows from the above data that the proposed mixtures provide the shortest time for the removal of cores from castings and contribute to the pd-dimensional accuracy of the cores (under heating conditions) and, therefore, castings. Table 1

Removal time of rods during knockout, min

eleven

Properties for mixtures

Forming (pressing) force, kg

Compressive strength in the reflecting state, kgf / cm

Temperature coefficient of linear expansion, hail. , at a temperature

with

100 400 600

Resize annealed sample mix after heating to, Z

Editor A.Vorovich Order 4564/11

Compiled by

Tehred I. Khodanich Proofreader-A.T sko

Circulation 757 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

table 2

12

ten

J table

Property Indicators for Pre-Blown Mixtures of Compounds 1-5

400

105

5.65 5.06 5.81

0.15-0.25

Claims (1)

MIXTURE FOR THE PRODUCTION OF CASTING RODS, including graphite powder and a binder based on phenol-formaldehyde resin, characterized in that, in order to improve the knockability of the rods and improve the quality of the rods by increasing their dimensional accuracy during heating, the mixture additionally contains sodium chloride and potassium permanganate when the following ingredients, May. 7a '. Binder on phenol based formaldehyde- noah resin 5-7 Sodium chloride 30-37 Permanganate potassium 0.2-0.4 Graphite- powder Rest SU „„ 1252014 * 1252014