SU448069A1 - The method of obtaining castings with cavities from black alloys by squeezing - Google Patents

Description

one

The invention relates to the field of foundry and can be used in the manufacture of castings with cavities using metal melted cores.

A known method for producing castings is by lowering the rods into metal-cast forms. The method involves obtaining the simplest parts like bushings using sand cores.

However, with this method, the durability of permanent molds in the casting of ferrous alloys is low, which is caused by the need for significant overheating of the alloy before pouring into the mold to ensure minimal effort when introducing a low-strength sand core into the alloy.

In addition, the manufacture of sand cores (especially a complex configuration) is time consuming and requires a vacuum system for securing the cores in the device.

The purpose of the invention is to improve the mechanical properties of castings.

For this, extrusion of the alloy is carried out in the temperature range of its crystallization by melting a metal rod after immersion in the alloy and solidification of the casting.

In order to reduce the cost of manufacturing the core, the casting is removed from the mold at a temperature 150-250 ° C below the solidus line, kept in a vertical position until the core material is completely melted, and the cast alloy is poured into the mold for the core.

An example of this method is the manufacturing process for a hollow casting of cast iron with a wall thickness of 15 mm, a maximum inner diameter of 90 mm and a height of 450 m. The temperature of the core and the temperature of the alloy poured into the mold are set in accordance with the above parameters. The core of the AL2 alloy, heated to a temperature of 250 ° C and covered with thermal insulating paint, is fixed in a movable rod holder. Cast iron (the content of the basic elements,%: C 3.5, Si 2, Mn-0.6) is poured into a steel form heated to 200 ° C and painted steel at 1270 ° C. Immediately after casting, the drive rod and

The rod is introduced into the alloy at a speed of 0.1 m / s.

After the casting is cooled to 950 ° C, the mold is disassembled, the cast is removed, held in a vertical position, followed by casting the alloy into the mold to form a rod.

The method is simple to implement. Lowering the temperature of casting the alloy into a permanent form allows reducing the thermal stresses in the walls of the form due to lowering the contact temperature and increasing the resistance of the permanent forms. Making the castings in the range of the crystallization temperature of the alloy or at the eutectic temperature makes it possible to improve the quality of the castings due to 5 grain refinements, improved mechanical properties and the elimination of shrinkage defects. The subject matter of the invention 1. A method of producing castings with cavities from ferrous alloys by squeezing, including pouring the alloy into the mold, immersing the rod into the alloy to the prescribed clearance from the bottom of the 10 4 form and removing from it a casting with a rod, characterized in that increasing the mechanical properties of castings; squeezing the alloy is carried out in the temperature range of its crystallization by melting after immersion into the alloy and solidification of the casting with a metal rod. 2. A method according to claim 1, characterized in that the casting is removed from the mold at a temperature 150-250 ° C below the solidification temperature, kept in a vertical position until the core melts, and then the metal is poured.