CS239274B1 - Apparatus for forming an ledeburitic structure by melting a rotating electric arc - Google Patents

Abstract

A device for creating a ledeburitic structure by melting with a rotating electric arc in the layer of the active part of the cam surfaces made of gray unalloyed or alloyed cast iron, which consists of a tungsten cooled electrode, which is shaped with a recess surrounding the cam as an equidistant of the outer surface at a distance of 3 to 5 mm, and a solenoid surrounding the tungsten electrode.

Description

The invention relates to a device for forming a ledeburitic structure on the camshaft cam surfaces of all internal combustion engines and pumps by means of a rotating electric arc.

Experience to date in the manufacture and use of the camshafts in terms of abrasion resistance is best suited to cast camshafts of gray or alloy cast iron, with the formation of a ledeburitic structure on the active portions of the cam surfaces.

In practice, this effect is achieved by cooling the surfaces during casting with metal coolers made of either gray cast iron or steel. The coolers can be either structurally separate, one for each surface, or made in the form of cages for cooling multiple cams at once.

The disadvantage of this casting technology is the relatively high laboriousness given by the production of refrigerators and their insertion into the mold, the requirement for high technological discipline and the organization of work in the foundry.

Coolers after a certain number of castings, about 20 to 30 pieces, must be replaced and replaced with new ones. If this is not done, the guaranteed casting parameters, such as hardness and quality of the ledeburitic layer, fluctuate.

Failure to comply with all these requirements may result in a high percentage of rejects in production. The price of castings produced in this way is high.

The above-mentioned disadvantages are overcome by a device for forming a ledeburitic structure according to the invention, which is based on a device for melting a layer by a rotating electric arc of the active part of cam surfaces of gray unalloyed or alloyed cast iron consisting of a tungsten cooled electrode. an outer surface at a distance of 3 to 5 mm, and a tungsten electrode encircling solenoid, optionally a cam surface.

The device for forming the ledeburitic surface layer of the active part of the camshaft cam surfaces consists of a tungsten electrode with internal cooling by means of a cooling medium whose internal recess is an equidistant cam outer shape, wherein the distance between the internal tungsten electrode recess shape and cam outer shape is given. optimal conditions for forming an electric arc of from 3 to 5 mm, wherein the shaped electrode comprises a solenoid, powered from an external source.

The camshaft cam and the shaped tungsten electrode are at rest with respect to each other. The applied magnetic field is created by a solenoid.

The main advantages of the device for forming the ledeburitic structure according to the invention are that the ledeburitic structure of the active part of the camshaft surface can be created without the use of metal coolers, the time required for melting the active part of the cam surface is shorter than using tungsten rod electrode. The surface of the cam, i.e. more even cooling, and thus preventing local cracks from initiating, is less internally loaded and the camshaft does not rotate, and as a result the camshaft clamping device is simpler and cheaper than when the camshaft needs to be rotated.

The accompanying drawing shows an example of a specific embodiment, in FIG. 1 with a camshaft in front view and in FIG. 2 with a camshaft in side and section view.

The formation of the ledeburitic structure of the camshaft cam surface from gray unalloyed or alloyed cast iron is characterized in that the surface layer of the camshaft cam surface 2 is initially melted by a rotating electric arc 9 _r, optionally in a protective shield, at a desired depth of 1 to 5 mm. The surface of the gas layer between the shaped tungsten electrode 3 and the camshaft surface 1 of the camshaft 1 with the electric arc rotation 9 formed by the introduced external magnetic field and subsequent rapid cooling due to the ambient atmosphere and the camshaft itself creates a ledeburitic structure.

The tungsten electrode 3, ^with internal cooling by means of coolant 5, has an internal shape in the form of an equidistant of the external shape of the cam 2, wherein the distance mezi between the internal shape of the recess of the tungsten electrode 6 and the outer surface of the cam is 3 075 mm. to form a rotating electric arc, wherein the shaped electrode comprises a solenoid 6, powered from an external source 7.

To produce a rotating electric arc 6, a conventional arc welding source 8 is used, which is customary for the type of arc cited. The camshaft 4 and the tungsten electrode 6 are in a fixed position relative to each other.

With the same effect, the tungsten electrode can be replaced by an electrode made of another material, in particular copper. The device is also suitable for the manufacture of other machine parts, such as valve lifters, rocker arms, camshafts, hubs, bushings, bushings, cylinders for various purposes, etc.

Claims (2)

SUBJECT OF THE INVENTION Apparatus for forming a ledeburitic structure by melting a rotating electric arc in a layer of active part of cam surfaces of gray unalloyed or alloyed cast iron, consisting of a tungsten cooled electrode, characterized in that the tungsten electrode (3) is shaped with a recess surrounding the cam (2) as equidistant the outer surface at a distance of 3 to 5 mm and the solenoid (6) encircles the tungsten electrode (3). Device according to Claim 1, characterized in that the solenoid (6) encircles the shaped tungsten electrode (3) and the cam surface (2).