SU1519823A1 - Method of hardening compacted moulds and cores by gas - Google Patents

Abstract

The invention relates to the field of foundry and can be used for curing molds and cores with a gas hardener. The purpose of the invention is to increase the productivity of the process and reduce the flow rate by reducing the purge time. The method includes two-side purging of the mold (rod) with gas, the time of initial purging is 0.05-0.5 times the complete curing of the mold (rod) with one-side purging, and the time of counter purging is 0.1-6.0 times the initial purge. 1 ill., 1 tab.

Description

The invention relates to the field of foundry products (production, and can be used to harden molds with rods; he is a hardener.

The aim of the invention is to increase the productivity of the process and reduce the flow rate (ase by reducing the purge time.

The drawing shows a graph of the relationship between the relative initial time 4a.ibH (jH of purging the mixture and the relative time of counter-purging.

The method involves purging the mold or rod with a hardener, first on one side, and then counter-purging from the opposite side, the initial purging is carried out for a time of 0.05-0.5 of the time required for complete curing of the mold with one-sided purging, and counter purging is carried out for a time of 0.1-6.0 times the initial purge time.

The method is carried out as follows.

The mold (rod) is fabricated according to a model plate (in a core box) having an internal cavity, which is interconnected alternately with the hardening gas supply line or with the atmosphere. Through the vents this cavity communicates with the working surface of the model plate and model (core box). After the mixture is compacted in a mold (rod) by any of the known methods, the mold (rod) is covered with a casing connecting alternately with a line for supplying hardening gas and compressed air. In the case of using closed core boxes, the second half of the box is performed with the internal cavity in the same way as the first half. Then, a hardening gas is fed into the casing or model plate, which, after passing through the vents, is filtered through the mold and the 1 and rod. After purging the mold or rod with a hardening gas during the resumer

with

00

1C

with

The time required for complete curing of the form (rod) with one-sided gas purge is performed at a time of 0.05-0.5, and the gas is filtered through the form (rod) from the opposite side for a time 0.1-6.0 from the time of initial blowing of the form (rod) until they are completely cured.

The indicated times for purging the mold (rod) were determined experimentally by visual observation of the curing process of the rod in a wooden plexiglass box holder. In order to visually monitor the curing process of the rod, 0.12-0.15 May was added to a mixture consisting of 94-95% silica sand and 5-6% liquid glass. including phenolphthalein, causing the mixture to turn a crimson color. When the mixture was flushed with carbon dioxide, the bleaching of the mixture occurred, and the bleached part of the mixture was solidified, while the remaining part of the mixture remained uncured.

Experiments have shown that with one-sided blowing of a compacted rod 220 mm high with a carbon dioxide consumption of 13 l / min, the curing time was 8–8.5 min, and the boundary between the cured part of the rod and its movement in the rod was clearly observed purge (table).

The results show that with a decrease in the time of initial purging of the mixture to 0.1 of the time of one-sided blowing, the total time of blowing is reduced, and with a further 1 decrease of the time of initial blowing, the total time begins to increase, remaining, however, less than the time of one-side blowing.

Processing the results of experiments using the least squares method allowed us to establish the relationship between the relative time of the initial purge of the mixture (tii / To) and the relative time of the counter-purge ():

 0.092 () -1.37

to

where T () is the time of one-sided purging of the mixture until it is completely hardened;

1N is the time of the initial purge of the mixture;

ta is the time of the opposite purge of the mixture;

Example 1. The initial purging of the rod with carbon dioxide is carried out within 3--3.5 min, i.e., on average, within 0.4 of the time of solidification of the rod with one-sided purging. In this case, the boundary of the cured part of the rod has spread to half its height. Then, the purge of carbon dioxide gas was reversed to the opposite and the purge was performed for 20–30 s, which was 0.1–0.15 of the initial time, after the first half of the rod, hardening by the second P (X1 | WINE (CONSIGNED

at the same time throughout the core. Total cure time rod sos. Tavilo 3.5 4 min. With a longer initial purge time, the initial hardening of the rod rises in volume, the larger the rod and the counter-blowing reduces the total solidification time of the rod slightly.

5 Example 2. Initial purge rod

carbon dioxide was produced within 2 min, i.e. within 0.25 of the time of solidification of the rod with one-sided purge. The boundary of the solidified part of the rod was cured by counter-blowing for 30–40 s, which is 0.25–0.30 from the time of the initial blowdown. The total curing time of the rod was 2.50-2.76 minutes. The nature of the curing rod at the initial and counter

5 purge remained the same as in Example 1.

Example 3. When reducing the time of initial purging to 0.15 from the time required before the rod is cured with one-side gas purging, the time of the opposite purge,: v, i of the rest of the rod equals c) met: h-initial purge, i.e. voo. The iioiiiCHHe of the Eile time is one. When yes. In this way, the initial blow time is reduced to 0.1 and less than one-way blow time. The character of the curing of the rod during counter-blowing changes and at the beginning of the counter-blowing the curing of the rod occurs along the gas propagation front as well as at the initial blowing, and then

0 in time, as the gas penetrates inside the rod, its curing occurs by volume. At the same time, the time of the counter purge of the rod begins to increase much faster than during the initial purge. Therefore, the lower limit of the purge parameters should be to accept the initial purge within 0.1 of the time required for the rod to fully cure with one-sided purge, and the counter purge should be performed for a time equal to the initial purge time. The use of this invention will reduce the time for purging the mold. whether a rod, which will allow to increase pro- cess (water content and to reduce the consumption of gas hardener.

Claims (1)

5 Formula of Invention (curing of compacted casting molds and rods with gas, including the initial gas blowing of the mold or rod n, and after its termination a counter blowdown, characterized in that, in order to increase the productivity of the process and reduce the gas flow rate by reducing the blow time, the initial blowdown carried out within 0.05-0.5 times the complete curing of the mold or rod with one-sided purging, and counter-purging carried out within 0.1-6.0 times the initial purge. The time of initial purging of the rod, with t ", The time of counter-blowing rod with tg, The total time of purging the rod T, s The ratio of the time of initial purging to the time of complete curing with one-sided purging. The ratio of the time of the counter blow to the time of the initial blow, tj Sn The ratio of total time to one-way time 75.0 40.0 22.5 16.5 15.0 7.5 3.75 10.9 13.5 14.0 13.5 21.3 75.0 48.0 33.4 30.0 29.0 21.0 25.0 0.53 0.3 0.22 0.2 0.1 0.05 0.2 0.48 0.82 0.93 1.8 5.7 purge 10.9 13.5 14.0 13.5 21.3 0.53 0.3 0.22 0.2 0.1 0.05 0.2 0.48 0.82 0.93 1.8 5.7 0.64 0.45 0.4 0.39 0.28 0.33 is N C g o / .6 h 1.2 1.0 0.8 0.6 0.4 0.1 about 0.1 0.1 0, b, Y 0.5 0.7 0.7 0.8 0.9 1.0 f