JPS58167849A - Piston machining method for internal-combustion engine - Google Patents

Abstract

PURPOSE:To efficiently form a piston which is favorable in its heat insulating ability in such a way that spot facing machining is done with the radius larger than that of the rim of a combustion chamber, and heat resistive material is thermally sprayed to stick on the face in a layer form. CONSTITUTION:The rim of a combustion chamber 2 is machined by spot facing 6 with a radius r1 larger than that of the rim of the combustion chamber 2, taking the center point of the combustion chamber as the center of radius, and releasing recessed portions 3, 4 are machined by spot facing 7 with the same radius r2 taking said center point as the center of radius. Depth of these spot facings 6, 7 is decided to be the thickness of the layer formed by thermal spray of heat resistive material. And, heat resistive material, such as metal or ceramics etc. is thermally sprayed on the spot facing 6, 7 so that layers 8, 9 of the heat resistive materials may be formed. Thus, the heat resistive materials 8, 9 are formed around the rim of the combustion chamber 2 and on the surfaces of releasing recessed portions 3, 4, and particularly countermeasures against heat load can be effectively provided at the crossing portion of the combustion chamber 2 and the releasing recessed portions 3, 4 where cracks are liable to occur.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of working force on a piston in an internal combustion engine.

An object of the present invention is to rationally and easily perform heat-resistant treatment on the top surface of a piston.

As shown in FIG. 1, in the case where the piston 1 has the combustion chamber 2 and the intake and exhaust valve relief recesses s3.4 and t in the Ijl direction, a crack 5 is formed at the intersection of the combustion chamber i12 and the relief recess 3.4 due to thermal load. This often occurs.

Conventionally, as a countermeasure against the heat load on the top surface of the piston, a method has been adopted in which the entire surface of the piston top surface is coated with a heat-resistant material, and a method in which the top surface of the piston is partially buried in a heat-resistant material. However, in the former case, the heat insulation becomes too high, leading to the generation of NOx or an increase in the heat load on the head side due to the rise in combustion temperature.In the latter case, the recess for burying the heat-resistant material is The cutting process is tedious, and there are drawbacks to efficient productivity.

The present invention provides a piston processing method, particularly a heat-resistant processing method, which overcomes these conventional problems.

Embodiment V of the present invention will be explained below with reference to FIGS. 2 to 4. 1 is the piston, 2 is the combustion chamber, 3.4 is the stator, and exhaust bar A.
The method for applying the heat-resistant material according to the present invention, which is the relief recess of No. 7, shall be applied in a layered manner by a continuous firing method.

Therefore, the present invention uses the center point of the combustion chamber at the periphery of the combustion chamber 2 as the radial center [half 1i larger than the radius of the periphery of the combustion chamber 20].
ft, the relief recess 3%4 has the same radius r as its center point. I will process it with 97 efforts. The depth of this counterbore 6.7 is equal to the amount of the sprayed layer of the heat-resistant material.

Then, as shown in FIG. 4, the counterbore 6.1 is coated with a heat-resistant material layer 8.9 by spraying a heat-resistant material such as metal or ceramics.

As a result, a heat-resistant material layer 8.9 is formed between the peripheral edge of the combustion chamber 2 and the surface of the relief recess li3.4 (the intersection of the combustion chamber 2 and the relief recess 3.4, where cracks are likely to occur). heat load vs.
lI can be effectively obtained.

Also, the counterbore 6.7 where heat-resistant material vII is emitted is on the 2nd floor of the combustion chamber! Every time I miss it! It has the advantage that it can be processed into thermal spraying using a general-purpose machine tool because it can be obtained by circular cutting with each center point of m$3.4 as a half-length center.

[Brief explanation of drawings]

No. 1- is an explanatory drawing showing the electrical parts on both the tops of the piston, No. 211I'! A thousand-picture diagram of a piston showing an embodiment of the present invention,
No. 31a is an enlarged sectional view of No. 21!3A-A, showing the well-formed seat-socket form, No. 4m+tlllllL2
It is an enlarged cross-sectional view of one layer at @, showing a state in which a heat-resistant material layer is formed. ! @...Piston, 2...Combustion chamber, 3...Intake pulp relief recess, 4--Exhaust pulp relief recess, 6.7
... Sitting 9.8.9 ... Heat-resistant material layer. Figure 4

Claims (1)

[Claims] In a piston that has a combustion chamber on the top surface, and a concave part that extends partially over the combustion chamber to release suction and exhaust pulp, the periphery of the combustion chamber is set radially around the center point of the combustion chamber, and is wider than the periphery of the combustion chamber. 9 machining is carried out with a large circle.The relief recesses of the suction and exhaust valves are counterboreed with the same diameter with the center point of the radius as the center, and a layer of heat-resistant material is applied to these counterbored parts. A method for processing a piston in an internal combustion engine, characterized in that the piston is thermally sprayed.