JPS59113122A - Radiation fusion treatment for internal combustion engine piston by electron beam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses an electron beam of a transferred beam method to locally irradiate and melt a groove that is gouged out after irradiation and melting, a flank area of an annular groove of a piston for an internal combustion engine. Depending on the method of processing, if the area of relatively low loading is immediately adjacent to the wear-loading surface to be created, or the loading surface is created from the material by a mechanical processing method followed after the irradiation-melting treatment, It also relates to methods of improving material properties that determine wear.

In the case of suitable materials, the material properties determining wear, e.g. hardness, cyclic bending resistance or other material properties, can be determined by locally irradiating and melting the workpiece with a laser beam (2) or an electron beam. It is known to improve. The melting process is carried out in such a way that the specific load surface to be subsequently processed lies in the area of the material to be irradiated and melted.

The effect underlying the property improvement is based on extremely rapid cooling, conditioned on heat transfer in the melting range, which leads to the formation of a clearly different microstructure from the base material.

For example, it is known to produce wear-loaded grooves, such as the first-line grooves of internal combustion engines, to produce two melting zones that correspond to the flanks of the groove and extend beyond the depth of the groove. It is also known to produce, to a greater or lesser extent simultaneously, two melting zones extending parallel to each other to a defined deflection state corresponding to the flanks of the groove by periodically displacing beam deflections.

A critical drawback of these known methods lies in the content and type of impurities contained in the material (3), which can lead to the formation of pores in the melting range, which can lead to obstruction of the groove flanks. It is about the results it brings. Furthermore, if the required irradiation melting depth exceeds a predetermined dimension, shrinkage stress may occur between the two melting zones, resulting in cracks reaching the groove to be machined. Another defect which occurs particularly during the melting process of castings is that the voids present in the casting leave hollow spaces in the melting region which can likewise become defective grooves.

The object of the invention is to provide a method which prevents the above-mentioned defects during melt processing with electron beams and which makes it possible to produce wear-resistant surfaces, especially for pistons of internal combustion engines.

The object of the invention is to develop a method for localized melting of a piston for an internal combustion engine, in particular in the area of the first annular groove, which prevents the formation of holes in the melting area and It must be possible to construct the groove in such a way that no cracks can occur that reach the groove in which it is formed, and the formation of voids is sufficiently reduced in the flank region of the groove.

(4) According to the present invention, this problem is solved as follows. That is, irradiation melting areas corresponding to the flank areas of the groove are created in segments of the same length extending in the longitudinal direction of the groove and facing each other and overlapping each other;
This is because the weld pools extending over the length of the segments each start from the flank plane of the groove and are guided parallel to this plane with a melting depth that decreases monotonically in the direction of the center of the groove. The above is accomplished as follows. That is, the electron beam is periodically and alternately deflected into the flank planes of the groove facing each other perpendicular to the longitudinal direction of the groove and increases monotonically from zero starting from the lateral planes. The beam deflection is guided in the direction of the center of the groove by the deflection velocity, and a two-dimensional beam vibration with a frequency considerably higher than that of the transfer action is added to and overlapped with the beam deflection, and the longitudinal direction of the groove is The amplitude of the beam vibration in the direction of It's getting smaller.

It is reasonable to use as the vibration figure an 8" in the longitudinal direction of the groove or a double parabola open to the center of the groove. Furthermore, the workpiece in which the electron beam is moved during the residence period of the segment It is advantageous to apply an overlapping sawtooth effect in addition to the beam deflection in the longitudinal direction of the groove so as to maintain an oscillation pattern that is stationary with respect to the surface.

The invention will be explained below with reference to exemplary embodiments according to the invention and to the accompanying drawings, which figures show a section through the development of the surface area of an internal combustion engine piston, the piston being shown in the area of the side surface of the piston link groove. It is melt-processed in.

In the illustrated workpiece piece 1, an annular groove 2, indicated by the dotted line, has to be created. The wear resistance of the material can be improved by localized irradiation melting with an electron beam 5 on the side faces 2a and 2b of the groove.

A groove 2 for radiation melting has to be dug (6) so that both sides 2a and 2b of the groove are in the melted material. The melting process is carried out by using an electron beam 5 to create irradiated melting areas belonging to the flanks 2a and 2b of the groove. For this purpose, the electron beam 3 is directed alternately into segments of the same length facing each other and overlapping each other. The weld pool 6, which extends over the length of the segment 5, is guided in each case with an irradiation melting depth that decreases monotonically starting from the side faces 2a or Fi, 2b of the groove towards the center of the groove. The electron beam 3 is deflected along and transversely to the predetermined annular groove 2 . To carry out the melting process, the electron beam 6 is deflected periodically and alternately in the longitudinal direction of the annular groove 2 onto the flanks 2a and 2b of the groove facing each other and with a monotonically increasing deflection from zero. It is guided from the side of the groove toward the center of the groove in the direction of arrow 7 at a high speed.

This deflection of the electron beam 3 is additionally overlapped by a two-dimensional beam vibration having a considerably higher frequency compared to the frequency of the transfer action. The amplitude of the component of the beam vibration characterized by the double arrow 8 and lying in the longitudinal direction of the groove is large compared to the diameter of the electron beam 6 and equal to the length of the segment 5 and determines the longitudinal elongation of the molten pool. do.

The transverse component of the beam vibration, characterized by the double arrow 9, is smaller than the longitudinal component and is smaller compared to the width of the annular groove. Since we add to the longitudinal deflection of the annular groove 2 an additional sawtooth effect of twice the frequency as compared to the transfer effect, the electron beam 3 moves in the longitudinal direction of the groove 2 in the 10 arrow direction during the dwell period. Sustains an oscillating figure that remains stationary relative to the surface of the material being moved. Neglecting vibrations, the electron beam 3 is therefore always guided along the arrow 7 over the segment 5 and is transferred from the segment 5 to the next segment along the dotted arrow.

[Brief explanation of the drawing]

The only accompanying drawing is a sectional view of a surface development to be treated to resist local heat (8) melting of an internal combustion engine piston, which is a preferred embodiment of the method according to the invention. 2a, 2b... Groove flanks 4a, 4b... Irradiation melting range 5... Segment 6... Molten pool agent Mitsuyoshi Ezaki agent Mitsufumi Ezaki (9) 113

Claims (1)

[Claims] (Re) A method of locally irradiating and melting a groove that is gouged out after irradiation and melting using an electron beam in a transfer beam method, preferably the flank range of an annular groove of a piston for an internal combustion engine. The irradiated melting areas (4a, , ib) belonging to the flanks (2a, 2b) of are formed in segments (5) of equal length facing each other and extending alternately in the longitudinal direction of the groove and overlapping each other. has been
A bath weld pool (6) extending over the length of the segments (5) each extends from the flank plane of the groove and is guided parallel to this plane with an irradiation melt depth that decreases monotonically in the direction of the center of the groove. All features and methods of being done. (2) The vibration pattern is characterized in that an "8" extending in the longitudinal direction of the groove or, in some cases, a parabola open to the center of the groove is used. (1) Claim 1 Method described. (6) In addition to the beam deflection in the longitudinal direction of the groove, an overlapping sawtooth effect is applied, thus the electron beam (
2. A method as claimed in claim 1, characterized in that 3) maintains in the longitudinal direction of the groove an oscillatory figure that is stationary with respect to the workpiece surface being moved during the residence period of the segment (5).