JPS59182055A - Method of grinding valve-seat surface - Google Patents

Abstract

PURPOSE:To enhance the circularity of a valve seat surface in the case of that the valve seat surface of a fuel injection valve for an internal combustion engine is ground, by providing such a process that the valve seat is ground by a grind stone which is rotated while being applied with reciprocating motion, but the reciprocating motion is stopped during the final grinding step. CONSTITUTION:In the case of that the seat surface of a valve body in a fuel injection valve is around, a grind stone 4 attached to the front end of a grind stone shaft 3 and having a conical front end is always applied with a reciprocating motion in the generatrix directions of the conical shape while being rotated to carry out grinding operation for the seat surface 2. The grinding process is carried out, in consideration with the relation between the cut depth and the time, in the following mentioned order, a step (a) of fast feed before cutting, a step (b) of rough-grinding, a step (c) of fine-grinding and a step (d) of spark- out having a cut-depth of zero. During the steps (a) through (c) the grinding is carried out with the grind stone being rotated while being reciprocated, and during the final spark-out step (d) the reciprocating motion is stopped so that the grinding is carried out with the grind stone being only rotated. With this process, the circularity of the thus worked valve seat surface is greately enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method of grinding a valve seat surface, such as a seat surface of a valve body of a fuel injector for an internal combustion engine.

<Prior art> Conventionally, when grinding the seat surface of the valve body of a fuel injection valve (the part where the Torhalb is seated), referring to FIG. The grinding wheel 4, which is attached to the tip of the grinding wheel shaft 3 and has a conical tip, is given reciprocating motion from beginning to end in the direction of the 1υ line of the circle 31t (direction G in the figure), and is rotated one by one, so that the seat surface 2 is rotated one by one. Grinding was being done.

However, with such conventional grinding methods, although the surface roughness of the products processed by this method is good, the reciprocating motion causes minute changes in the depth of cut, resulting in a decrease in roundness. Therefore, when used as a valve, there was a problem that hIJ tightness or airtightness was not good.

<Object of the Invention> In view of these conventional problems, the present invention provides a grinding method that can improve the roundness of the seat surface and make the surface configuration of the seat surface less likely to leak liquid. The purpose is to provide

<Structure of the Invention> Therefore, in the present invention, in the final step of grinding, the reciprocating motion is stopped and the rotational motion is used to perform (σ1 grinding).

<Example> Examples will be described below.

The grindstone used for grinding is as shown in Fig. 1, and the grinding process consists of rapid feeding steps a, i'u before cutting, as shown in Fig. 2, due to the relationship between time and depth of cut. The grinding process b is performed in this order, followed by the spark-out process d in which the R-grinding process C1 has a depth of cut of 0. In the steps a to c, grinding is performed by rotating the grindstone while applying reciprocating motion, and in the final spark-out step, the reciprocating motion is stopped and grinding is performed by observing the rotary motion.

As a result of actual processing using this method, the surface roughness and roundness were as shown in the table below compared to the conventional method.

In other words, the roundness was greatly improved. In addition, although the surface roughness is worse, looking at the surface configuration of the sea I surface, the ground surface in the conventional method is already as shown in Figure 3 + Al, whereas the ground surface in this method is It is already as shown in Fig. 3 FB+, and when used as a valve, it becomes a resistance in the direction of flow of oil, etc., so leakage from the ura etc. is less likely to occur. As a result, the yield in terms of oil tightness was actually improved by 6 to 7%.

Incidentally, if the spark-out step d is omitted as shown in FIG. 4, the reciprocating motion may be stopped in the final TFI polishing step C.

Further, as shown in FIG. 5, if the (1j grinding) step C and the spark-out step d are omitted, the recipe may be made to stop one movement during the final rough grinding step or at a later stage thereof.

<Effects of the Invention> The present invention is as described above, and by performing grinding by stopping the reciprocating conveyance J of the grindstone in the final step of grinding, the direction of roundness of the sheet surface can be improved. This provides the advantage of being able to prevent liquids from leaking while also making it possible to configure the surface structure of the sheet surface to prevent liquids from leaking.

[Brief explanation of drawings]

Fig. 1 is a sectional view for explaining the interlocking of the grinding wheels used for grinding the valve seat surface, Fig. 2 is a diagram showing an embodiment of the present invention, and Fig. 3 fAl, (Bl is the conventional method and A schematic diagram showing the surface configuration of the seat surface according to the present method, and FIGS. 4 and 5 are diagrams showing other embodiments, respectively. 1... Valve body 2... Seat surface 3.・
- Grinding wheel shaft 4... Grinding wheel patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima Figure 1 Figure 2 H No. 3 (A) Figure 4 Time (B) Figure 5 Open

Claims (1)

[Claims] When grinding a valve seat surface in the shape of a circle 't (t), a grindstone in the shape of a circle SfC is rotated while giving reciprocating motion in the direction of the generatrix of the cone, and the reciprocating motion is stopped in the final process. A method for grinding a valve seat surface, which is characterized by grinding only by rotational motion.