SU1720790A1 - Mould for making iron castings - Google Patents

Abstract

The invention relates to foundry, in particular, to the formation of cast iron hollow thin-walled products. The purpose of the invention is to improve the quality of castings and reduce labor costs for embossing. In the mold, the metal insert is made of a material with a low melting point, and the thickness of the insert is a certain part of the width of the working cavity of the mold. 1 hp ff, 1 ill.

Description

The invention relates to foundry, in particular, to the formation of cast iron hollow thin-walled products.

The purpose of the invention is to improve the quality of castings and reduce labor costs for embossing.

The drawing shows the mold, cut

The casting mold contains flasks 1, into which refractory material 2 (sand-clay mixture) is molded, gating system 3, ventilation ducts 4, hollow insert 5 made of low-melting material, for example aluminum, and an opening for discharging molten material of insert 6 made in parts of the form. The mold is placed on the platform of the casting conveyor 7, and under it is a chute 8 for draining the insert material. Between the refractory material 2 of the mold and the insert 5, there is a working cavity 9. As a formula for calculating the thickness of the insert 5, an empirical relationship is adopted:

d 2 7b (gzal -tie) 0.23 + 553-3

West Light (tnn.BCT-tnep) j + Savst

where two hundred insert thickness;

5ot - casting thickness (width of the working cavity);

Light is the average heat capacity of the insert material;

Light-heat melting insert;

Tzal - metal pouring temperature;

tie - casting temperature when removing the insert;

trm.BCT melting point of insert material;

tnep is the overheating temperature of the insert material;

West is the specific weight of the insert material;

tf - mold temperature before pouring.

By substituting the known characteristics of the insertion and casting materials as well as the process parameters into the formula, it is possible to obtain the required thickness values of the inserts. Prine in the temperature of casting iron in preS /

with

N С x

: with

1280-1350 ° C, temperature of the form 15-30 ° C, use one of the following materials: copper, bismuth, tin, lead, zinc, aluminum, and receive limits for variations in insert thickness 15-140% of the width of the working cavity. For specifically selected material this interval is significantly narrowed. For example, for aluminum, 5Bcg is 0.6-1.0 bots, which is consistent with the experimental results. Box 5 may be 6% painted with graphite paint completely or only at the location of the gating system.

Foundry form works as follows.

In the flasks, the refractory material 2 is molded using model tooling. In this case, the gating system 3 and the outer surface of the working cavity 9 are molded. The mold may preferably include two flasks 1, which are molded separately. The insert 5 is made of aluminum by die casting. After the sprue has been removed and painted, it is installed in the lower half of the mold, located in one of the flasks 1 and placed on the mold platform of the filling conveyor 7, then the lower half of the mold is covered with the upper one located in the other of the flasks 1 and both flasks are fastened together. Then, through casting system 3, cast iron is poured into the cavity of form 9. The cavity 9 is filled. The molten iron transfers heat to the refractory material 2 and box 5, which are heated from this heat. The heated air from the cavity of the insert 5 is forced out through the ventilation ducts 4 and the opening 6. Due to the high thermal conductivity of the material of the insert 5, it warms up quickly, taking heat along the contact surface with

cast iron, which contributes to uniform and favorable for the strength characteristics of the crystallization of the casting. As the insert 5 warms up and thanks to its hollowness

it is softened, which helps to reduce the shrinkage resistance of the casting and improve its quality. Further heat transfer from the casting to the insert 5 causes it to melt and overheat above

the melting temperature of the insert material to give the necessary fluidity, after which the material of the insert 5 is removed by gravity through the drain hole and then along the channel 8. Thus the insert 5

is removed from the cast immediately after crystallization. Then, the mold, together with the casting of the cone, is fed to the knockout grid, where the casting and cleaning of the casting is carried out.

The proposed mold as compared to the known one has advantages that provide an increase in the quality of castings and a reduction in labor costs during embossing.

Formula of the invention 1. The mold for the production of iron castings containing refractory lining, metal inserts, working

cavity and gating system, characterized in that, in order to improve the quality of castings and reduce labor costs during embossing, the insert is made of a fusible material and placed in the working

the mold cavity, in the lower part of which there is a drain hole for the molten material of the insert, and the thickness of the insert is 0.15-1.4 the width of the working cavity. . 2, the Form according to claim 1, characterized by

the fact that the insert is made of aluminum.

Claims (2)

Claim 1. A mold for producing cast iron castings containing a refractory lining, metal inserts, a working cavity and a gating system, characterized in that. that, in order to improve the quality of castings and reduce labor costs during knocking out, the insert is made of fusible material and placed in the working cavity of the mold, in the lower part of which a drain hole is made for the molten material of the insert, and the insert thickness is 0.15-1.4 of the working width cavities. . 2. The mold according to claim 1, characterized in that the insert is made of aluminum.