JPS619973A - Production of engine valve - Google Patents

Abstract

PURPOSE:To obviate the genaration of the weld crack, pinholes and lack of fusion in the hard-faced part of a blank material for an engine valve consisting of a martensitic material contg. Fe and Cr as essential components by subjecting said blank material to hard-facing by a plasma arc and specifying the nozzle diameter of a plasma arc torch. CONSTITUTION:The plasma arc is formed between the above-mentioned blank material and the above-mentioned torch and the carrier gas such as Ar contg. prescribed material of stellite, etc. from a powder supply device 36 is supplied to the passage 20 of the torch 10 and is ejected from a nozzle 38 to hard-face the groove 54 of the material 48. The diameter D1 of the nozzle 38 of the torch 10 is so determined as to satisfy 0.6D2<=D1<=1.2D2 with respect to the groove width D2 of the groove 54. The speed of the hard face welding is preferably set at >=4mm./sec. A defectless valve face is formed by the hard-facing on the material 48 by the above-mentioned method, by which the intended engine valve is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method of manufacturing an engine valve, and in particular, to a method of manufacturing an engine valve, using a martensitic material containing Fe and Cr as main components as an engine valve material, and applying hard overlay to the engine valve material. The present invention relates to a method for manufacturing a target engine valve by forming a valve face surface.

BACKGROUND OF THE INVENTION Engines for automobiles and the like are provided with engine valves that open and close intake ports and exhaust ports in order to supply mixed gas into the combustion chamber or discharge combustion exhaust gas from the combustion chamber. Since this engine valve is used in a high temperature environment, it is required to have excellent heat resistance and wear resistance. For this reason, austenitic heat-resistant steels such as 5
By using UH36 material as the engine valve material and hardfacing the engine valve material to form the valve face surface that seats on the valve seat of the intake or exhaust port, it has excellent heat resistance and wear resistance. engine valves are manufactured.

On the other hand, since austenitic heat-resistant steels such as the S U H36 material mentioned above are generally expensive, in recent years relatively inexpensive 5UHI
Martensitic heat-resistant steels containing Fe and Cr as main components, such as I material and 5UH3 material, have come to be used as the engine valve material.

Problems to be Solved by the Invention However, martensitic heat-resistant steel containing Fe and Cr as main components has high quench hardenability, and conventional gas method and Ti
In case of hardfacing using the C method, weld cracks may occur if sufficient preheating is not performed. In addition, the main component F
E and Cr are easily oxidized, and during welding, these oxides may get mixed into the molten metal and cause pinholes, or the bond strength between the overlay material and the engine valve material may be impaired, resulting in poor fusion. There were some problems.

Means for Solving the Problems In order to solve the above-mentioned problems, the method for manufacturing an engine valve according to the present invention involves hardfacing an engine valve material made of a martensitic material containing Fe, Cry as main components. To form the valve face surface and manufacture the desired engine valve, a plasma arc is formed between the plasma arc torch and the engine valve material, while a predetermined powder material is The powder material is guided into a plasma arc, melted, and a predetermined hardfacing is performed on the engine valve material, and the nozzle diameter = DI of the plasma arc torch is the groove width of the hardfacing portion; D2 It is characterized by satisfying the following formula: % formula %].

Further, in the present invention, the welding speed for hardfacing, that is, the relative movement speed in the welding direction between the plasma arc torch and the engine valve material, is as follows:
Although it varies depending on the magnitude of the welding current, etc., it is necessary to perform hardfacing with a good bead shape.
It is desirable to set the value above. The upper limit of this welding speed is generally about 20 W/sec, but if conditions such as welding current are appropriately set, a higher speed can be used. Moreover, at this time, the plasma arc torch and the engine valve material can be relatively moved (oscillated) in a direction perpendicular to the welding direction, if necessary.

Furthermore, the valve face of an engine valve is generally formed in a tapered shape around the outer periphery of the valve bulk.
The axis of the engine valve material is 1 1 with respect to the vertical direction.
If the engine valve material is rotated around the axis at an angle of 0° to 60°, and a plasma arc torch is placed above the inclined engine valve material to perform °ζ hardfacing,
The bead shape is not compromised due to gravity acting on the molten metal.

In addition, the powder materials to be hardfacing include stellite type (CO haze), colmonoid type (Ni haze), Fe-
It is possible to use various overlay powders such as Cr-based (Fe heath), and the size is set appropriately considering the difficulty of melting, etc., but in general -]00 to +35
A spherical material with a mesh size of about 0 is preferably used.

Effects of the Invention When hard overlay is applied to an engine valve material made of martensitic material in this manner, weld cracks and pinholes may occur in the hard overlay, as will be clear from the examples described later. This solves the problem of poor fusion between the fill material and the ennon valve material. Moreover, since a powder material is used as the overlay 44, the time required for hard overlay can be shortened compared to the case where a bar material is used, and the hard overlay can be easily automated. Furthermore, since hardfacing is performed using a plasma arc, hardfacing with a good bead shape can be obtained even if the depth of the groove to be hardfacing is shallow, and the amount of hardfacing material used can be reduced. Significant savings can be made.

EXAMPLESNext, in order to clarify the present invention more specifically, the present invention will be explained in detail.In order to facilitate understanding, first, a plasma deposition welding apparatus that can suitably carry out the present invention will be explained. will be explained based on FIG.

In the figure, 10 is the tip of a plasma arc torch (hereinafter referred to as a torch) arranged in the vertical direction.

Such a torch 10 is equipped with a tungsten electrode 12 in the center, and a torch inner cylinder 14 is provided on the outside of this electrode 12.
and a torch outer cylinder 16 are arranged coaxially at a predetermined distance from each other. Annular passages 18 and 20 are formed between the electrodes 12 and the torch inner cylinder 14, and between the torch inner cylinder 14 and the torch outer cylinder I6, respectively.

The passage 18 is connected to the plasma gas supply device 2 via piping 22.
4, and plasma gas such as argon gas is supplied thereto. The plasma gas supplied into this passage 18 is ejected downward from a nozzle 30 provided at the tip of the torch inner cylinder 14.

Further, the passage 20 is connected to a carrier gas supply device 34 via a pipe 32, and further, a powder supply device 36 is connected to an intermediate portion of the pipe 32, and a predetermined powder is supplied from the powder supply device 36. Materials are now available. That is, a carrier gas containing a predetermined amount of powder material is supplied to the passage 20 and is ejected downward from a nozzle 38 provided at the tip of the torch outer cylinder 16.

As the powder material, it is possible to use various types of hardfacing material powders such as stellite type, colmonoy type, and Fe-Cr type, and as the carrier gas, non-containing materials such as argon gas and helium gas can be used. An active gas is used.

On the other hand, the nozzles 3 of the torch inner cylinder 14 and the torch outer cylinder 16
0 and 38 have cooling water passages 40 and 42, respectively.
are arranged to cool both nozzles 30 and 38. Furthermore, a shielding gas made of an inert gas such as argon gas or helium gas is supplied to the tip of the torch outer cylinder 16 from a shielding gas supply device 44 through a pipe 46. By blowing out in a substantially cylindrical shape toward the axis of the torch 10, the welding area is shielded from the atmosphere.

An engine valve material 48 to be subjected to hardfacing welding is attached below the torch 10 configured as described above. This engine valve material 48 is a material for an engine valve that opens and closes an intake port and an exhaust port in order to supply mixed gas into the combustion chamber of an engine such as an automobile or to discharge combustion exhaust gas from the combustion chamber. So, 5UHII material whose main components are Fe and Cr,
It is made of martensitic heat-resistant steel material such as 5UN3 material. The engine valve material 48 includes a shaft portion 50 and an umbrella portion 52, and an annular recess 5 to which hardfacing is applied is formed on the outer periphery of the shoulder portion of the bulk portion 52 located on the shaft portion 50 side.
4 (groove portion) is formed. In addition, the broken line shown in the recessed part 54 in FIG. 1 shows the state where the hardfacing was applied.

The engine valve material 48 is attached to a mounting shaft 56 that is inclined at an angle θ with respect to the vertical direction, with its axis aligned with the axis of the mounting shaft 56 via a cooling banking 58. It is designed to be rotated together with the mounting shaft 56 around the axis A at a predetermined speed.

In the state of being attached to the mounting shaft 56 in this manner, the uppermost portion of the recess 54 formed in the bulk portion 52 of the engine valve material 48 is located vertically below the nozzle 38 of the torch 10. When the engine valve material 48 is rotated around the axis A, hardfacing is sequentially applied to the annular recess 54. Here, the nozzle diameter D□ of the nozzle 38 is set to satisfy the following formula: 0.6D2≦D≦1.2D2 with respect to the groove width D2 of the recess 54.

A predetermined pilot current is supplied between the electrode 12 of the torch 10 and the torch inner cylinder 14 from a pilot power source 60, and a backing 58 to which the electrode 12 and the engine valve material 48 are attached is connected. During this period, a predetermined welding current is supplied from the main power source 62. In addition, the electrode 12 and the torch inner cylinder 14
A high frequency oscillator 64 for ignition is inserted between the pilot power source 60 and the pilot power source 60 in parallel.

Next, a procedure for applying hard overlay to the engine valve material 48 using the above-mentioned plasma overlay welding apparatus will be described, which constitutes one embodiment of the present invention as it is.

First, a pilot current is supplied from the pilot power supply 60 to generate a pilot arc between the tip of the electrode 12 and the nozzle 30 of the torch inner cylinder 14, and at the same time, plasma gas is supplied from the plasma gas supply device 24 into the annular passage 18. supply As a result, a plasma arc is formed at the tip of the electrode 12.

Thereafter, a welding current is supplied from the main power supply 62 between the electrode 12 and the backing 58 to transfer the plasma arc formed at the tip of the electrode 12 to the engine valve material 48, and at the same time, the carrier gas supply device 34 and the powder supply A carrier gas containing a predetermined powder material is passed from the device 36 to the passage 2.
Supply within 0. The powder material supplied into the passage 20 is ejected from the nozzle 38, melted by a plasma arc, and overlay welded to the recess 54 of the engine valve material 48. At this time, shielding gas is blown out from the tip of the torch 10, so that the molten powder material and the recess 54 are not affected by oxygen in the air.

In this state, by rotating the engine valve material 48 around its axis A, the part of the recess 54 to be overlaid welded moves, and the annular recess 54 formed on the outer periphery of the umbrella part 52 moves. Hardfacing will be sequentially applied to the entire circumference.

At this time, it is also possible to reciprocate (oscillate) the torch 10 in a direction perpendicular to the welding direction, that is, in the left-right direction in FIG. 1, if necessary.

Here, when hardfacing is performed on the engine valve material 48 made of martensitic heat-resistant steel material in this way,
There is almost no occurrence of weld cracks or pinholes in the hardened build-up portion, or poor fusion between the build-up material and the engine valve material 48. Further, since a powder material is used as the overlay material, the welding time can be shortened compared to the case where a bar material is used, and the automation of hard overlay can be facilitated.

Incidentally, on the upper side, a recess 54 is formed in a portion of the engine valve material 48 where hard overlay welding is not to be performed, but such a recess is not necessarily necessary when hard overlay welding is performed using a plasma arc. For example, even on a flat surface, a good bead-shaped hardfacing can be obtained. therefore,
Compared to the conventional gas method or TIG method, which requires forming predetermined recesses and performing hardfacing, the amount of hardfacing material used can be significantly reduced.

Then, the engine valve material 48 that has been hard faced in this way is then subjected to a predetermined process such as grinding on the hard faced part, and is then installed at the intake or exhaust port of the combustion chamber. A valve face surface that sits on the valve seat is formed,
Engine valves with excellent heat resistance and wear resistance are manufactured.

In addition, in the above explanation, engine valve cumulative month 48
Although we have explained the case where the material is made of mantenside heat-resistant steel material such as 5UHII material and 5UH3 gold, 5LIH3
Of course, it is possible to implement the same method even if the material is made of austenitic heat-resistant steel material such as No. 6 material.

In addition, the engine valve material 48 is a backing 5 for cooling.
The banking 58 is attached to the mounting shaft 56 via the engine valve material 48.
It may be provided as necessary, taking into account the size of the welding area and welding conditions such as welding current.

Furthermore, the plasma overlay welding apparatus described in 1 is merely an example of an apparatus that can suitably carry out the present invention, and manufacturing an engine valve using the apparatus is an embodiment of the present invention. The present invention is not limited in any way by these descriptions, and it goes without saying that the present invention may be implemented with various modifications and improvements based on the knowledge of those skilled in the art.

The method for manufacturing an engine valve according to the present invention has been described above in detail.Next, in order to specifically clarify the effects of the present invention, the bead shape of the hardfacing portion formed according to the above example, The results of the investigation regarding hardness (H#C), weld cracks, pinholes, and poor fusion will be specifically explained in comparison with comparative examples.

Example l A spherical shape of Stellite 16 was applied to an automobile engine valve material 48 with a valve diameter (outer diameter of the bulk part 52) of 40 dragons made of 5UH3 material (0.4% C-11% Cr-1% Mo-remaining Fe). When hardfacing powder material (-100 to +350 mS), the welding current is 80 to 100 A, the plasma gas supply rate is 1°5 to 1.81/min, and the powder carrier gas supply rate is 5°Q. e /+ll1n, the shielding gas supply amount is 25.012 /1111n%, the inclination angle θ to the axis of the engine valve material 48 is 45°, the groove width D2 of the hardfacing part is 5.3mm, and the nozzle diameter is Table 1 shows the results of examining the bead shape, etc. of the hardfacing portion when the welding speed was changed as appropriate, and when oscillation was further performed and when oscillation was not performed. In addition, the hole 10 of the comparative example is a case where hardfacing was performed using a rod material of Stellite 16 by a gas method.

As is clear from Table 1, in the hardfacing of floors 1 to 7 according to the present invention, weld cracks, pinholes, and poor fusion occur in the hardfacing parts. There is nothing to do. In addition, the welding speed is relatively slow at 3wb/s6C.
In this case, the welding amount of the base material (engine valve material 48) increases and the overlay material is diluted, the bead shape is slightly impaired and the hardness of the overlay part decreases, but there is no practical problem. It can be seen that in other cases where the welding speed is 4 mm/sec or higher, a hardfacing with a good bead shape and sufficient hardness can be obtained. In this example, the welding speed was set to 1.
This has only been carried out up to 2 sn/sec, but depending on welding conditions such as welding current, a sufficiently satisfactory hardfacing can be obtained even at 20 n/see or higher.

On the other hand, in the case of Comparative Example No. 8, the nozzle diameter,
is smaller than the range of the present invention, the bead shape is impaired and fusion failure occurs. In addition, in the case of failure 9 in which the nozzle diameter D1 is larger than the range of the present invention, the penetration amount of the base material (engine valve material 48) increases and the overlay material is diluted, resulting in a hard overlay portion being formed. As hardness decreases, fusion failure occurs. Furthermore, in the case of No. 10 in which hardfacing was performed using the gas method, weld cracks, pinholes, and even poor fusion occurred in the hardfacing, making it impossible to obtain a satisfactory hardfacing.

Example 2 SUHII material (0,5% C-8,5% Cr-remaining Fe)
When hardfacing powder materials of various overlay materials onto an automobile engine valve material 48 having a valve diameter (outer diameter of the bulk part 52) of 55 mm, the welding current is 80 to 100 A, and the plasma gas supply amount is 1. .5 to 1,81/min, the powder carrier gas supply rate was 5.0β/min, and the shielding gas supply rate was 25.012/min.

When the nozzle diameter D1, the groove width D2, and the inclination angle θ of the axis A of the engine valve material 48 are changed as appropriate under the conditions that the welding speed is 10 mm/sec and oscillation is not performed, the bead shape of the hardfacing part Table 2 shows the results of the investigation. In addition, floors 19 to 21 of the comparative example are cases where hardfacing was performed using a bar material by a gas method.

As is clear from Table 2, m11-I8 according to the present invention
In hardfacing, weld cracks, pinholes, or poor fusion do not occur in the hardfacing. In addition, in the case of positive 13 where the inclination angle θ of axis A is as large as 65°, 5°
In the case of a small diameter 14, the bead shape is damaged due to the gravity acting on the molten metal, but there is no problem in practical use.
It can be seen that in other cases within the range of 10° to 60°, hardfacing with a good bead shape and sufficient hardness can be obtained. In addition, VMS is an Fe-based overlay material.
585-B is Nimon as a build-up material for Ni heath.
IC 80 A is used in each case, but it goes without saying that other overlay materials can be used, and the overlay materials for Co heath include not only Stellite 132 and '12, but also
Other materials such as 16 in Example 1 can be used.

On the other hand, in the case of Comparative Examples tI&l19 to 21, weld cracks and pinholes occurred in the hardfacing part, and poor fusion occurred, and satisfactory hardfacing could not be obtained. There wasn't.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating an example of an apparatus that can suitably implement the present invention. 10: Plasma arc torch I 38: Nozzle 48: Engine valve material Dl: Nozzle diameter D2: Groove width θ: Inclination angle

Claims (3)

[Claims] (1) When manufacturing the desired engine valve by hardfacing an engine valve material made of martensitic material containing Fe and Cr as main components to form a valve face, a plasma arc torch and the engine are used. While forming a plasma arc between the valve material and a powder carrier gas, guiding a predetermined powder material into the plasma arc,
The powder material is melted and a predetermined hardfacing is applied to the engine valve material, and the nozzle diameter: D_1 of the plasma arc torch is set to the groove width of the hardfacing: D
A method for manufacturing an engine valve, characterized in that the following formula is satisfied for _2: 0.6D_2≦D_1≦1.2D_2. (2) The manufacturing method according to claim 1, wherein the welding speed of the hardfacing is 4 mm/sec or more. (3) While rotating the engine valve material around its axis with its axis inclined at 10° to 60° with respect to the vertical direction, a plasma arc torch is placed above the inclined engine valve material and cured. The manufacturing method according to claim 1 or 2, which performs overlaying.