JPS61261609A - Poppet valve made from titanium alloy - Google Patents

Abstract

PURPOSE:To reduce production cost and improve durability by fixing the metal padding of Ti-Al system alloy at the stem edge of a valve stem and the seat of a valve umbrella of a poppet valve made from titanium alloy. CONSTITUTION:A poppet valve 20 used for intake, exhaust valves, etc. of an internal-combustion engine has a valve stem 1 and a valve umbrella 2. In this, metal paddings 5, 6 are padded at the seat of the valve umbrella (2)'s valve sheet, and the stem edge of the valve stem 1. Each metal padding 5, 6 is formed of a basic material of Ti with Ti-Al intermetallic compound, such as having the content of more than 30% of Al. The outer periphery of the valve stem 1 forms a surface treatment layer 4, such as Cr plating, etc. This can only necessitate flame coating of the Ti-Al system alloy to the seat of the valve umbrella 2 and the stem edge of the valve stem 1, eventually reducing production processes and improving abration resistance, compared with conventional poppet valves requiring brazing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a mushroom-shaped valve made of titanium alloy, which is used as a monthly intake valve, exhaust valve, etc. of an internal combustion engine.

[Conventional technology]

In recent years, titanium alloy supply and exhaust valves have come to be used in some high-speed engines.

FIG. 2 shows an example of a conventional titanium alloy supply and exhaust valve 10. Titanium alloys are lightweight and have high heat resistance, but they are hard and
In terms of wear resistance, it is slightly inferior to ordinary steel supply and exhaust valves, so as shown in the figure, the shaft end of the valve stem 1 is equipped with a steel plate (CO
A tip 3 made of a base alloy) is brazed to the valve stem 10, and a surface treatment 4 is applied to the surface of the valve stem 10 to improve wear resistance. 2 is a valve head portion.

[Problems to be solved by the invention]

However, in such conventional mushroom-shaped valves, since the shaft end hesterite 3 is brazed, the number of manufacturing steps for the valve increases, leading to a rise in manufacturing costs.
There is a problem that the durability of the valve is low because the seat part is heavily worn (not shown).

The present invention has been made in view of the above, and an object of the present invention is to provide a method for manufacturing a mushroom-shaped valve with low manufacturing cost and high durability.

[Means and effects for solving the problems] In order to solve the above problems, the present invention uses a 7i-AF alloy such as a Ti-Al intermetallic compound at the shaft end of the valve shaft portion and the seat portion of the valve head portion. It is characterized by being overlaid by thermal spraying etc. This mushroom-shaped valve requires fewer man-hours to manufacture than the conventional mushroom-shaped valve in which a Stellite chip is brazed.
Since Al-based alloys have high wear resistance, the durability of the valve is also improved.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIG. 1. Reference numeral 20 is a mushroom-shaped valve used for internal combustion engine monthly intake, exhaust valves, etc., 1 is a valve stem portion of the valve 20, and 2 is a valve head portion. be. Reference numeral 5 denotes an overlay that is deposited by thermal spraying on the seat portion of the valve head portion 2 with the valve seat (not shown), and 6 is an overlay that is deposited by thermal spraying on the shaft end of the upper valve shaft portion. . The metal layer 5.6 is made of a 7i-Al intermetallic compound based on 7i and containing 30% or more of Al. 4 is a surface treatment layer such as R plating formed on the outer periphery of the valve stem portion 1.

To a method of manufacturing a supply/exhaust valve 20 having the above configuration.
To explain further, first, the outer shape is machine cut to the required dimensions, and two built-up parts on the seat part of the valve head part 2 and the shaft end part of the valve stem part 1 are scraped off.

Next, a metal layer 5.6 made of 'l'1-Al intermetallic compound is deposited on both the shaft end of the valve stem part 1 and the seat part of the valve head part 2 by thermal spraying, and then diffusion heat treatment is applied. Rub. Furthermore, after surface treatment 4 such as chrome plating is applied to the outer periphery of the valve stem portion 1, the outer surface is finished by polishing or the like to complete the valve.

〔Effect of the invention〕

The present invention is constructed as described above, and according to the present invention, it is only necessary to thermally spray a Ti-Al alloy such as 7i-Al intermetallic compound onto the seat portion and the shaft end of the valve stem portion, which is different from the conventional method. Compared to mushroom-shaped valves in which Stellite is brazed, the number of manufacturing steps is reduced, and the wear resistance of the seat and valve stem ends, which are subject to impact loads, is improved. Therefore, a mushroom-shaped valve with low manufacturing cost and high durability can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing one embodiment of the present invention, and FIG. 2 is a view corresponding to FIG. 1 showing an example of a conventional mushroom-shaped valve. 20...Mushroom-shaped valve, 1...Valve shaft, 2--Valve head, 5.6-・Mori metal □ Dirt! Second flash

Claims (1)

[Claims] A mushroom-shaped valve made of a titanium alloy, in which a metal plate made of a Ti-Al alloy is fixed to the shaft end of the valve stem and the seat of the valve head.