RU1826040C - Reference specimen for determining machinability of gray cast iron castings - Google Patents

Abstract

The invention relates to methods for evaluating the hardness of gray castings of various grades and can be used to determine the presence of surface bleaching on castings of this class of materials. The purpose of the invention is to increase the reliability and simplify the assessment of the machinability of gray iron castings by producing structures of gray, half and white cast iron on a reference monolithic sample. The essence of the invention lies in the fact that the reference sample for evaluating the machinability of gray iron castings with calibrated hardness areas is cast from unalloyed cast iron containing carbon and silicon in an amount of 4.4 to 4.6%, in the form of a multi-stage rectangular prisms with a step thickness difference of 40 to 20 mm and a minimum step thickness of 6 to 10 mm 1 ill. 1 table. (/ WITH

Description

The invention relates to methods for studying the physical and chemical properties of materials, in particular to methods for assessing the hardness of castings of various grades of gray cast iron, and can be used in foundries, mechanical and thermal workshops to determine the presence of surface bleach on castings of this class of materials.

The purpose of the invention is to increase the reliability and simplify the assessment of the machinability of gray iron castings by producing structures of gray, half and white cast iron on a reference monolithic sample.

The goal is achieved in that the reference sample for evaluating the machinability of castings from gray cast iron with calibrated hardness sites

made of unalloyed cast iron containing carbon and silicon in an amount of 4.4 to 4.6%, in the form of a multistage rectangular prism with a step thickness difference of 10 to 20 mm and a minimum step thickness of 6 to 10 mm.

The drawing shows a General view of a reference sample.

The reference sample contains steps with structures of gray, half and white cast iron having flat grinding work surfaces calibrated by hardness. The surface hardness of the steps in the reference sample varies from 160 to 450 HB. The reference material is unalloyed cast iron, containing the sum of carbon and silicon in the range of 4.4-4.6%. The reference sample is made by casting in a sandy clay form using raw.

00

U O O 4 O

In the process of manufacturing castings, due to the different cooling rates of the metal, a structure of gray, half and white cast iron is formed in the steps of different thicknesses of the standard.

The table shows examples of the manufacture of a reference sample and hardness indices of various stages when the device parameters change within the limits specified in the claims and beyond.

After making a reference sample, the Brinell hardness is accurately measured and indicated at each step.

The reference sample for evaluating the machinability of gray iron castings is intended for use in foundries, mechanical and thermal workshops as a fixture or device for pre-sorting gray iron products, such as castings, heat-treated parts, which are subjected to subsequent machining on metal-cutting machines.

The products are pre-sorted by evaluating the hardness of the material using a standard file, for which the test surface of the product is cleaned of burnout or scale.

Before testing, the suitability of a standard file for use as a tool for assessing the hardness of a material by moving it with a flat wide side without applying a pressing force on the working surface of each tared step of the reference sample is checked.

The suitability of the file is judged by its sliding when moving on the surfaces of the solid steps of the standard and on the adherence on the surfaces of the soft steps of the standard. The hardness assessment, i.e. machinability of the tested surfaces of products. The file slides when moving around

and

10

fifteen

twenty

25

thirty

35

40

45

a material with a hardness higher than 380 HB, adhesion is well felt when the surface hardness is up to 241 units on the HB scale, and partial slippage is felt if the material has an intermediate hardness.

The use of the standard makes it possible not only to detect the presence of a bleached surface crust on the product, but also to estimate, within certain limits, the hardness of the processed surface of the material, i.e. identify and brand of gray cast iron.

The feasibility of using a reference sample for evaluating the machinability of gray castings is to simplify and cheapen the method of accelerated non-destructive detection of surface bleach on gray castings, to determine the grade of gray cast iron by the relative hardness of the product material, as well as to increase the sensitivity and the reliability of the method for evaluating the workability of products using a file.

Accelerated product sorting according to a preliminary assessment of machinability makes it possible to increase the machining productivity of gray castings and increase the service life of the cutting tool.

Claims (1)

SUMMARY OF THE INVENTION A reference sample for evaluating the machinability of gray iron castings made with hardness calibrated pads, characterized in that, in order to increase the reliability and simplify the assessment by producing gray, half and white cast iron structures on a monolithic sample, the sample is cast from unalloyed cast iron containing carbon and silicon in the amount of 4.4-4.6%, in the form of a multi-stage rectangular prism with a difference in thicknesses of steps of 10-20 mm and a minimum step thickness of 6-10 mm.