SU114148A1 - A method of making casting molds and cores by applying a contour mold with a model - Google Patents

Description

When casting parts and products from ferrous and non-ferrous metals into molds, permanent metal chill molds are usually used, which is associated with the inevitable destruction by the molten metal of the working surface of the molds with the formation of "hot cracks in the body of the casting and the need to chill them.

Cortical casting is also used, which is associated with the expenditure of an expensive phenol-formaldehyde fixer and the need to polymerize and dry the molds. Moreover, casting dimensions are often not sufficiently accurate due to warping, swelling and inaccuracy of the cortical forms.

The described method of making casting molds and cores by applying a contour flask with a model allows to obtain molds that are not related to the listed disadvantages, ensures the production of castings with an improved surface and eliminates the need for their bleaching.

This is achieved by using

casting metal molds with a cortical layer deposited on their inner surface, which is created by pressing in under pressure of 5-6 atm into the space between the contour flask and the model inside it refractory mass forming the working cavity.

To create a refractory layer on the inner surface of the metal form {contour flask), viscous masses based on graphite, chromium iron, fluorspar or sufficiently crushed clad sands, for example, of the following composition are used: 95% graphite, 2% aluminum oxide and 3% chrome iron

65-75% water and 1.5-2.50 / 0 fastener (KB, SB, GTP, G, etc.) are added to this mixture.

For a better subsequent separation from the created cortical layer of the model located inside the mold, the surface of the model (before the introduction of viscous mass) is covered with a spray dispenser with a layer of separation emulsion, for example.

containing 98 / o of machine oil and 2% kerosene or 5% ethyl polysiloxane, 3% household soap and 92% water;

The technology for making the mold by the described method includes the following operations:

a) assembling and centering metal contour jackets placed inside the metal model and mounted on the flasks of the gating system;

b) injection under pressure of 5–6 scm of visco-flowing refractory mass into the space between the inner walls of the contour flasks and the outer walls of the model;

c) a connector of the form and removal of the model from it;

d) assembly of the mold for pouring;

e) metal pouring;

e) embossing the casting and the molded layer.

Knock out burned mass after appropriate grinding, dosing and mixing is used to make new batches of viscous mass.

Mass injection is carried out in a pre-heated to a temperature of 250-350 ° C. Upon filling the mold, the mass is heated by the hot walls of the flask and dried.

Channels and outlet openings are closed in the walls of the flasks, which are closed by retractable pins pressed by springs.

The duration of injection molds for castings weighing 50-100 kg is about 30-60 seconds. The same amount of time is spent on the process at a layer thickness of up to 10 mm.

Subject invention

A method of manufacturing casting molds and cores by applying a contour mold with a model, characterized in that, in order to improve the surface of the castings and to eliminate them, the viscous fluid fire is pressed into the space between the contour flask and the model under pressure of 5-6 atm. normal mass forming the working cavity of the form.