SU990403A1 - Core production method - Google Patents

Description

(54) METHOD FOR MAKING RODS

one

The invention relates to foundry, in particular, to the technology of manufacturing cores.

A known method of making rods consists in filling the core box with a mixture, compacting it, then removing the rod from the box and drying it in a dryer Lij.

However, the known method is laborious, and the cycle of production of sturgeon is very long.

The closest technical solution to the invention is a method of manufacturing rods, including aanoating the curable mixture of a preheated core box, compacting the mixture, striking the rod in the box and removing the hardened rod 2,

In connection with the high hardening rate of the mixtures in the manufacture of rods in a heated snap, the physicological properties of the hardened rods largely depend on the duration of the rods in the case. Premature

Removing the rod from the crate leads to its destruction or the production of a rod with reduced mechanical properties. An increase in the duration of hardening above the optimum leads to a partial destruction of the binder material in the surface layer, which significantly reduces the quality of the rod.

The determination of the required duration of hardening of the rod is carried out by the method of technological samples, which consists in the manufacture and technological tests of standard samples. Such tests are usually carried out upon receipt of a new batch of binder material and debugging of the operating mode of the serr.

In fact, the minimum duration of the hardening of the rod differs significantly from the established one, since during storage of the binder material its reactivity decreases. In addition, the duration of the hardening is affected by the failure in dispensing the initial 399 components of the mixture and the quality of their mixing. In practice, to prevent possible destruction of the rod while removing it from the plate, the duration of the hardening of the rod is set to be more optimal. As a result, the performance of the core machines is reduced and the quality of the finished cores deteriorates. The aim of the invention is to improve the quality of the cores, optimize the hardening process and increase the productivity of the core equipment,. The goal is achieved according to the method, which includes filling the pre-heated core box with a hardened mixture, compacting the mixture, holding the rod in

Table 1 3 and the extraction of the hardened rod, the measurement of the electrical conductivity of the rod is carried out directly during the hardening process and the rod is removed from the bling when the conductivity reaches 1-15% of its variation range corresponding to the complete solidification of the mixture. The electrical conductivity of the bonding materials used in the manufacture of the rods in the heated equipment during the hardening process varies considerably. In tab. 1 shows the results of measuring the electrical conductivity, phenol alcohol of a density of 1226 kg / m, solidified at 220 ° C.

When a binder material is heated at first, its conductivity increases slightly as a result of an increase in the degree of ion doping, and then hardening begins, which is accompanied by a significant decrease in electrical conductivity. The minimum value of electrical conductivity corresponds to a fully cured bonding material. Further exposure at high temperature leads to the destruction of the binder, accompanied by the release of

1.13

0.88

As the rod solidifies, its electrical conductivity also changes and reaches the minimum value at the instant of time, which corresponds to the complete hardening of the bonding material. However, with the extraction of carbon, which increases the increase in electrical conductivity (Table 1).

The electrical conductivity of a core mixture prepared on an electrically conductive binder continent determines the content of the binder in the mixture and the uniformity of its distribution over the surface of the grains, as well as the degree of compaction. our mixture. In tab. 2 shows the results of measuring the initial electrical conductivity of a mixture with different contents of pheno-alcohol,

Table 2

1.70

1.77

1.53

It is not possible to obtain maximum strength at the moment when the minimum of the electrical power is achieved. This is due to the fact that due to the heat accumulated by the rod during heating, its solidification occurs

after removing from the crate. As a result, the destruction of the cured binder material begins under the Boaweit heat outside the core box.

In order to prevent this occurrence, the rod must be removed until the minimum value of electrical conductivity is reached so that

Hardening time

min. Strength by 1.02 1.28 gase, fo p, MPa Electrical conductivity, K 10-, 9.5 5.54.25 Cm. Analysis of experimental data shows that it is necessary to remove samples from the box until the minimum conductivity is reached, corresponding to the duration hardening equal to 4 minutes. Maximum strength is achieved when samples are removed from the box 3 minutes from the start of hardening. The initial electrical conductivity of the mixture is 153x1O m, and the final, corresponding to the complete solidification of the binder, 4 ,. Thus; In this case, the range of variation of conductivity of the said material is 148.80. When the initial electrical conductivity of the mixture changes, the final conductivity also changes. The range of variation for this bonded material remains constant. The electrical conductivity of the samples for solidifying 3 min is 4.25 k, i.e. To obtain maximum strength, these samples must be removed from the box at the moment of time when their conductivity is 4.25-fO.-.--., 00% - .. of the range of variation of the conductor-sh. mixture when fully cured binder material. For smaller than standard samples, rods having a low heat

after finding a yadenck, - outside the crate, the binder material solidified due to the accumulated heat.

In tab. Table 3 shows the results of the determination of the strength of standard samples (eights) and the change in the electrical conductivity of a mixture containing 3% phenol alcohol and cured during

.

Table 3

4 1.21 1.09 0.98 O, 82 4.2 O 4.28 4.54 5.49 low accumulation capacity, the hardening process should be stopped when the value of electrical conductivity corresponding to 1-1.5% of the range of variation of the conductivity of the mixture is reached. With an increase in the size of the rod, and consequently, in the heat-accumulating ability, the removal of sterokn from the box should be carried out at a value of electrical conductivity, which is 1O-15% of the range of its change in the process of hardening. Thus, for a rod weighing 14–16 kg, the hardening process must be interrupted when an electrical conductivity of 22.310 ° C is reached, which corresponds to 14.99% of the range of variation of the conductivity of the mixture. Thus it is possible to obtain the maximum strength of the rod. The value of electrical conductivity, at which it is necessary to remove the rod from the box, depends on its dimensions and is determined experimentally. In the case of variation of the initial properties of the binder material or its content in the mixture, the initial and minimum electrical conductivities change. The range of electrical conductivity change during the hardening process remains constant, thanks to this, the proposed method allows the maximum use of the binding properties of the bond material, optimizes the process of manufacturing rods and increases the productivity of rod equipment due to 100% control of all rods produced.

7 9904038

Claims (1)

The claims of the rod in the process of hardening A method of manufacturing rods, including the conductivity value, which is filling the curable mixture with a 15% range of change, corresponding to the previously heated rod, which hardens the mixture, snionca, compaction of the mixture, holding the rod in the drawer, and removing the hardened core, and holding the hardened core, and holding the hardened core to the surface of the specimen; Expertise that, in order to improve the quality, Optim-1, Matveenko I.V. and Tarsky V, L. Eadii of the process of hardness and turning. Equipment for foundries M., Map productivity rod equipment, 1976, p. 139-143. measurement, measured by electric wire-2, Ibid, p. 143-149. and remove the rod from the box when reaching