SU827247A1 - Method of producing casting moulds and cores - Google Patents

Description

sandblasting feed it into a heated snap-in, in which the core of the mold forms are cured from the surface to the depth of the layer sufficient to obtain the required manipulator strength of the core of the mold 3. The long-term cure of the cores in the heated snap-in is depending on their dimensions and masses from 40-45 seconds to several minutes. However, it is desirable to further increase the rate of hot curing of the rods and shapes, which will allow to increase the productivity of the machines, lx., Prepare, x.

The aim of the invention is to reduce the duration of hot-hardening of the rods and shapes and to increase the productivity of the core aggregates.

To achieve this goal, a method for manufacturing casting cores and molds, including the preparation of a sand-resin mixture containing a refractory filler, a synthetic resin and an acidic hardener, sandblasting and sandblasting, and releasing the core or mold, is proposed. which consists in the fact that in the manufacture of a sand-resin mixture an acidic hardener is introduced to obtain the weight ratios of the synthetic resin and the acidic hardener, respectively (1: 0.6) - (1: 0.1 ) and serves the mixture in the equipment, heated to a temperature of 30-50 ° C above the degradation temperature of synthetic resin.

iB as mineral hardener, mineral acid or its acid salt or organic carboxylic acid is introduced according to the described method.

The ratio of synthetic resin and acid hardener (1: 0.6) - (1: 0.1) is typical for cold-hardening mixtures with resins with l: and an offset between 5-20 minutes. This indicator of lucidity means that the mixture according to the proposed method is more reactive than the sand-resin mixtures that are commonly used in the manufacturing process of sterling on heated equipment. Due to this circumstance, and also taking into account the increased heating temperature of the equipment, usually after 15-30 seconds a hard crust with a thickness from 5 to mm is formed on the surface of the nli form of the rod, creating sufficient strength properties for extracting sterols n-snap, hardening the remaining part of the mixture There is an elimination of the rod from the tooling due to the chemical reactions that take place in the heat-accelerated binding process of the normal cold-accumulated process accumulated in the surface layer.

Since the contact time of the mixture with the heated equipment is only 15-30 seconds, it becomes possible to heat the core box to higher temperatures than is usually the case when manufacturing rods in a heated equipment, namely, to a temperature of 30-50 ° higher temperature degradation binder. At the same time, the process of thermal decomposition of the binder manages to partially develop on the contact surface of the mixture with the snap-in, which facilitates the free removal of the rod from the snap-in without the use of special release lubricants. At the same time, the surface of the rod retains high hardness and strength.

When the ratio of synthetic resin and acidic hardener is more than 1: 0.6, the irretrievable losses of the sand and resin mixture, not realized within one cycle of manufacturing rods, increase, and at a specified ratio of less than 1: 0.1, the curing of hot rods is not achieved. and forms.

If the heating temperature of the equipment is higher than the upper stipulated limit (more than 50 ° C above the degradation temperature of the resin binder), the surface layer can be burned out and the surface quality will deteriorate.

By reducing the heating temperature of the equipment below the lower contingent limit (less than 30 ° C above the degradation temperature of the resin binder), the rate of hot hardening of the surface layer is reduced.

In the implementation of the described method, the mixture is prepared immediately before use in a mixing preparation unit mounted on a shotgun assembly. Since the time of the survivability of the mixture is limited, the stock of the mixture should not exceed the amount of the mixture consumed during the survivability. The prepared mixture is adjusted in a core box heated to a temperature of 30-50 ° C above the degradation temperature of the resin binder. After the release, 15-30 seconds in the surface layer of the rubbing: a solidified crust with a thickness of 5-15 mm is formed. After the crust has formed, the core is removed from the hot snap-in and placed on a stack, where it cools and hardens the mixture throughout the volume.

The invention is illustrated by the following example.

In tab. 1 shows the compositions of mixtures No. 1-5, obtained by the proposed method, and in table. 2 — the modes of their hot-ventilated holes in the cold state.

Table 1

table 2

Indicators for mixtures number

Claims (3)

Claim 1. A method of manufacturing casting cores and molds, including the preparation of a sand-resin mixture containing a refractory filler, synthetic resin. And an acid hardener, sandblasting and sanding it into heated equipment and curing the core or mold, characterized in that reduce the duration of curing of the rods and molds and increase the performance of the rod aggregates, when preparing the sand-resin mixture, an acid hardener is introduced to obtain weight ratios of the synthetic resin and acid verditelya respectively (1: 0.6) - (1: 0.1), and said mixture is fed into snap heated to a temperature of the synthetic resin degradation. 2. The method according to π. 1, characterized in that as the hardener is injected mineral acid or its acid salt. 3. The method according to π. 1, characterized in that an organic carboxylic acid is introduced as an acid hardener.