CS238126B1 - Flux for crankshaft bolt renovation - Google Patents

Abstract

According to the solution, a mixture of a melting flux based on silicon dioxide, manganese dioxide and calcium oxide, in an amount of 78 to 82% by weight, with a ceramic flux containing carbon and chromium, in an amount of 14 to 16% by weight, is used as a flux. The flux is particularly advantageous in the renovation of crankshaft journals for internal combustion engines.

Description

The present invention relates to a flux for refurbishing the crankshaft journals by applying an electric arc deposit of a weld material consisting of a mixture of a flux and a ceramic flux.

Fluxes for welding crankshaft journals containing up to 46% by weight are known. % silica, 0.3 wt. % titanium dioxide, 3.1 wt. % alumina, 28 wt. % manganese oxide, 7 wt. % of calcium oxide, 7.2 wt. % magnesium oxide, 0.1 wt. % ferrous oxide, 0.9 wt. of potassium oxide, 0.4 ϊ wt. sodium oxide and 5.3 wt% calcium fluoride.

These fluxes are used either alone or mixtures thereof, optionally added to fluxes of graphite, ferrochromium and the like. These fluxes are among the glass, high / mica and manganese fluxes.

The shortcomings of the flux include poor arc-burning stability during AC welding, the generation of a certain amount of harmful gases, the need to clean the corroded surface before welding to prevent pores from forming in the welds.

Glassy fluxes cause a higher porosity of cladding than pumiceous fluxes. When surfacing with high-siliceous and manganese fluxes, the deposit is only alloyed with silicon and manganese.

A certain disadvantage of the technology of using known fluxes, which limits its further expansion, is that all equipment, including the necessary material, is expensive and that the renovation itself is relatively labor intensive, which adversely affects its cost.

Another known technology of welding the worn crankshaft journals under the flux is that, as a rule, a spring wire of φ 1.6 to 1.8 mm, with a carbon content of 0.7 to 0.8%, is used as the weld material.

The flux is a specially prepared flux mixture with powder graphite, powder ferrochrome and water glass. In this formulation, the mixture ensures the self-hardening of the weld deposit and the high surface hardness of the entire functional part of the pin in the range of 56 to 62 HRc.

Using the materials in question and adhering to the prescribed welding and machining technology of the crankshaft journals, very good results are achieved. Weld beads are regular and do not show cracks or other defects. However, after machining the surfacing, there are noticeable cavities on the sliding surface of the pins.

According to the invention, these flaws are overcome by a flux for refurbishing the crankshaft journals by applying an electric arc welding material consisting of a mixture of flux and ceramic flux.

Its essence is that the flux, in an amount of 78 to 82 wt. contains 25 wt. % silica and 10 wt. % of calcium oxide and ceramic flux, in an amount of 14 to 16 wt. contains 0.5 wt. % carbon and 3.5 wt. of chromium. In another aspect, the flux may contain a trace amount of up to 5% by weight. graphite.

The basic effect of the flux according to the invention is that it facilitates the restoration of the part to its original size, high quality renovation and the possibility of surfacing layers with special properties, the possibility of using conventional machinery and a quick return on investment, including high labor productivity and overall economic advantages of renovation.

The flux according to the invention is explained in more detail below on two exemplary embodiments.

Example 1

The weld material containing C, Mn, Si, Cr and a mixture of fluxes consisting of a flux and a flux ceramic without flux of graphite were used to perform an experimental weld on the crankshaft journals of a steel engine according to ČSN 41 5142.

80 wt. % flux, 15 wt. Ceramic flux.

The weld pin diameter was 80 mm, the weld wire diameter was 1.6 mm. To create the arc, the voltage was 22 to 24 V at 180 to 190 A.

Welding was carried out without prior preheating of the base material. The hardness of the weld deposit achieved after re-grinding to a functional dimension was 45 to 50 HRC. In terms of macrostructure, the surfacing was homogeneous and free of surface cracks. Perfect bonding of the welded ¹ layer with the base material was achieved.

Example 2

Welding was performed similar to Example 1 except that 81 wt. % flux, 14.3 wt. flux of ceramic flux and 4.7 wt. graphite.

The results obtained were essentially the same, only the hardness after re-grinding to a functional dimension was higher and was 50 to 55 H @ 2.

Claims (2)

SUBJECT OF THE INVENTION What is claimed is: 1. A flux for the renovation of crankshaft journals by arc welding consisting of a mixture of a flux and a ceramic flux, characterized in that the flux, in an amount of 78 to 82% by weight, contains 50% by weight of flux. % of silica, 25 wt. % manganese oxide and 10 wt. calcium oxide and ceramic flux, in quantities 14 to 16 wt.%, Containing 0.5 wt. % carbon and 3.5 wt. of chromium. 2. A flux according to claim 1, characterized in that it contains a trace amount of up to 5% by weight. graphite