JP2006037923A - Engine valve and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the wear resistance of the shaft end part of an engine valve and the fatigue strength of the shaft end part and the area near a groove part thereof. <P>SOLUTION: This engine valve 1 comprises a shaft part 2, a bevel part 3, the groove part 4, and the shaft end part 5, and is formed of an aluminum-containing titanium alloy. A quenchable heat resisting steel tip 6 is heated and brazed to the tip of the shaft end part 5. This method of manufacturing the engine valve comprises a first heating step for heating the surfaces of the shaft part 2, the bevel part 3, the groove part 4, and the shaft end part 5 to form them in a needle-like structure, a step for pressingly holding the heat resisting steel tip 6 at the tip of the shaft end part 5 through a brazing material 7, a second heating step for heating parts of the heat resisting steel tip 6, the shaft end part 5, the shaf part 4, and the shaft part 2 and brazing the heat resisting steel tip 6 to the tip of the groove end part 5 and forming at least the surfaces of parts of the groove part 3 and the shaft part 2 in an equiaxial structure or a solution structure, and a rapid cooling step for hardening the heat resisting steel tip 6 by rapidly cooling the heated portion thereof to hold parts of the shaft part 2, the groove part 4, and the shaft end part 5 in the equiaxial structure or the solution structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine valve used as, for example, an intake valve and an exhaust valve of an automobile engine, and a manufacturing method thereof.

  In recent years, titanium alloy engine valves have been used as intake valves and exhaust valves due to demands for higher rotation and lighter weight of automobile engines. As shown in FIG. 7, a general engine valve 31 includes a shaft portion 32, an umbrella portion 33 formed at one end of the shaft portion 32, a groove portion 34 formed at the other end of the shaft portion 32, and a shaft end. Part 35. As shown in FIG. 8, this type of engine valve 31 is provided with a spring retainer 42 in a groove 34 via a cotter 41, and a valve spring 43 made of a compression spring is provided between the spring retainer 42 and the cylinder head. Provided. Therefore, an upward urging force (in the direction of the arrow) in FIG. 8 is applied to the groove 35 by the valve spring 43.

  Here, an engine valve made of a titanium alloy is likely to cause adhesion with other metals due to its activity, and its wear resistance is not sufficient. For this reason, in the engine valve, particularly, the shaft tip portion including the shaft end portion 35 that frequently contacts the rocker arm or the like is required to have higher wear resistance than other portions. Therefore, various technologies relating to this type of titanium alloy engine valve are disclosed in Patent Documents 1 to 4 below.

  In the engine valve described in Patent Document 1, an oxygen diffusion layer or an oxygen diffusion layer and a carburized layer are formed in a portion where friction resistance is required in order to improve the friction resistance of an engine valve made of titanium alloy. Yes.

  As shown in FIG. 9, the engine valve described in Patent Document 2 is formed by friction-welding a hardened and hardened steel rod-like member to the end portion of the shaft portion 32 opposite to the umbrella portion, The shaft tip portion 36 having wear resistance is formed by processing. The shaft tip portion 36 includes the groove portion 34 and the shaft end portion 35 described above.

  The engine valve described in Patent Document 3 is a cold press-fitting by quenching and hardening a steel chip that has been processed in advance into a recess formed in the top surface of the shaft end of a titanium alloy engine valve. is doing.

  As shown in FIG. 10, the engine valve described in Patent Document 4 has a shaft end member 37 made of heat-resistant steel and a nickel-based brazing material 38 at one end of a shaft portion 32 of an engine valve made of titanium alloy. It is attached. The shaft end member 37 includes a groove portion 34 and a shaft end portion 35.

JP 2002-97914 A (page 2-3, FIG. 1) JP-A-5-59919 (second page, FIG. 2) Japanese Patent Laid-Open No. 5-146921 (second page, FIGS. 2 and 3) JP-A-5-202706 (page 2-3, FIGS. 1 and 2)

  However, the engine valve described in Patent Document 1 is not sufficient in thickness because the oxygen diffusion layer (oxidation treatment) and the carburized layer are the only layers formed at the site where friction resistance is required. For this reason, there is a possibility that each layer cannot withstand the stress at the end of the shaft.

  In the engine valve described in Patent Document 2, a shaft tip portion 36 made of a steel rod member includes a groove portion 34, and the shaft portion 32 and the shaft tip portion 36 are joined below the groove portion 34. For this reason, every time the umbrella portion of the engine valve is seated on the valve seat, the urging force of the valve spring acting upward on the groove portion 34 acts in a direction to separate the shaft tip portion 36 from the joint portion with the shaft portion 32. As a result, a decrease in bonding strength became a problem. In addition, it is difficult to control the position of the joining interface between the shaft portion 32 and the shaft tip portion 36.

  In the engine valve described in Patent Document 3, since the steel tip is only press-fitted into the recess, the steel tip may fall out of the recess while an impact such as a cam is applied to the steel tip.

  In the engine valve described in Patent Document 4, when a nickel-based brazing material is used as a titanium alloy in the first place, it forms an embrittlement, so that it has been difficult to apply to functional parts. For this reason, the shaft portion 32 is limited to the titanium-aluminum intermetallic compound. Further, depending on the heat treatment conditions during brazing, the fatigue characteristics of the groove 34 may be degraded. Further, even in this engine valve, the urging force of the valve spring acting upward on the groove portion 34 acts in the direction of separating the shaft end member 37 from the joint portion with the shaft portion 32, so that the joint strength is reduced. It became a problem.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an engine valve that improves the wear resistance of the shaft end portion and the fatigue strength in the vicinity of the shaft end portion and the groove portion, and a method for manufacturing the same. There is.

  In order to achieve the above object, the invention described in claim 1 includes a shaft portion, an umbrella portion formed at one end of the shaft portion, and a groove portion and a shaft end portion formed at the other end of the shaft portion. The engine valve is made of a titanium alloy containing aluminum, and is intended to braze a heat-resistant steel tip to the tip of the shaft end.

  According to the configuration of the invention, since the heat resistant steel tip is brazed to the tip of the shaft end portion, the shaft end portion comes into contact with a member such as a rocker arm via the heat resistant steel tip. Further, since the heat-resistant steel tip is located on the opposite side of the shaft portion across the groove portion, the brazed portion of the heat-resistant steel tip is not affected even if the urging force of the valve spring acts on the groove portion.

  In order to achieve the above object, according to a second aspect of the present invention, in the engine valve according to the first aspect, at least the surfaces of a part of the shaft part, the groove part, and the shaft end part are made of an equiaxed structure or a solution structure. It is comprised and it is set as the meaning that the part other than a part of shaft part and the umbrella part were comprised from the acicular structure | tissue.

  According to the configuration of the invention, in addition to the action of the invention according to claim 1, since at least the surfaces of a part of the shaft part, the groove part and the shaft end part are composed of an equiaxed structure or a solution structure, The fatigue crack growth rate of the part becomes slower than the part of the acicular structure. Moreover, since the part other than a part of the shaft part and the surface of the umbrella part are composed of a needle-like tissue, heat resistance as an engine valve is ensured as usual.

  In order to achieve the above object, the invention described in claim 3 includes a shaft portion, an umbrella portion formed at one end of the shaft portion, a groove portion and a shaft end portion formed at the other end of the shaft portion. A method of manufacturing an engine valve formed of a titanium alloy containing aluminum, wherein a heat-resistant steel chip that can be hardened and at least a part of a shaft part, a groove part, and a shaft end part are heated and heated. The purpose is to braze a heat-resistant steel tip to the tip of the shaft end.

  According to the configuration of the invention described above, at least the surface of a part of the shaft part, the groove part and the shaft end part and the heat-resistant steel chip that can be hardened are heated, so that the surface texture of these parts is optimized. Further, since the heat-resistant steel tip is brazed to the tip of the shaft end by the heating, the heat-resistant steel tip is relatively easily joined to the tip of the shaft end.

  In order to achieve the above object, according to a fourth aspect of the present invention, in the method for manufacturing an engine valve according to the third aspect, at least a surface of a shaft portion, a groove portion and a shaft end portion and heating of a heat-resistant steel tip are performed. Is high-frequency induction heating performed for a predetermined time in a vacuum or under an inert atmosphere, and is intended to be rapidly cooled after the heating.

  According to the configuration of the invention described above, in addition to the action of the invention according to claim 3, at least the surface of the shaft portion, the groove portion and the shaft end portion and the heat-resistant steel tip are high-frequency in vacuum or under an inert atmosphere. Since it is induction-heated and rapidly cooled after the heating, the heat-resistant steel chips are quenched, and brazing is performed in high quality in a short time.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the method of manufacturing an engine valve according to the third or fourth aspect, at least a surface of a shaft portion, a groove portion and a shaft end portion, and a heat resistant steel tip The heating and holding temperature is β transformation point −100 to + 100 ° C., not less than the liquidus of the brazing material and not less than the quenching temperature of the heat-resistant steel chip, and the heating and holding time is 1 to 10 minutes. Intended to be

  According to the configuration of the invention described above, in addition to the action of the invention according to claim 3 or 4, quenching and brazing of the heat-resistant steel tip, part of the shaft part, groove part, and the structure of at least the surface of the shaft end part Optimization is done in one step.

  In order to achieve the above object, an invention according to claim 6 includes a shaft portion, an umbrella portion formed at one end of the shaft portion, and a groove portion and a shaft end portion formed at the other end of the shaft portion. A method of manufacturing an engine valve formed of a titanium alloy containing aluminum, the first heating step of heating the shaft portion, the umbrella portion, the groove portion and the shaft end portion to form a needle-like structure as a whole, and the shaft A process of pressing and holding a heat-resistant steel tip that can be hardened through a brazing material to the tip of the end with an appropriate load, and heating the heat-resistant steel tip, the shaft end, the groove, and a part of the shaft, A second heating step in which a heat-resistant steel chip is brazed to the tip of the end portion, and at least the surface of the shaft end portion, the groove portion, and a part of the shaft portion is equiaxed structure or solution structure; and immediately after the second heating step And a rapid cooling step for rapidly cooling the heated portion.

  According to the structure of the said invention, a heat-resistant steel chip | tip is hardened simultaneously with brazing suitably for a shaft end part. At the same time, an equiaxed tissue or solution structure is formed on at least the surface of a part of the shaft part, the groove part, and the shaft end part, and a needle-like structure is formed on the part other than the part of the shaft part and the umbrella part. The

  In order to achieve the above object, according to a seventh aspect of the present invention, in the method for manufacturing an engine valve according to the sixth aspect, the second heating step is performed at a high frequency in a vacuum or under an inert atmosphere for a predetermined time. The purpose is induction heating.

  According to the said structure, in addition to the effect | action of the invention of Claim 6, a heat-resistant steel chip | tip is brazed in high quality in a short time by high frequency induction heating in a vacuum or in an inert atmosphere.

  In order to achieve the above object, according to an eighth aspect of the present invention, in the method for manufacturing an engine valve according to the sixth or seventh aspect, the heating holding temperature in the second heating step is β transformation point −100 to + 100 ° C. And it is more than the liquidus line of a brazing material, more than the quenching temperature of a heat-resistant steel chip | tip, and the heat holding time is 1 to 10 minutes.

  According to the configuration of the above invention, in addition to the action of the invention according to claim 6 or 7, brazing and quenching of the heat-resistant steel tip and optimization of at least the surface structure such as the shaft end and the groove are performed in one step. Done in

  According to the first aspect of the present invention, the wear resistance of the shaft end portion and the fatigue strength in the vicinity of the shaft end portion and the groove portion can be improved for an engine valve made of a titanium alloy containing aluminum.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the fatigue strength in the vicinity of the shaft end portion and the groove portion can be further increased, and the high temperature creep strength of the shaft portion and the umbrella portion can be increased. The durability of the engine valve can be improved while ensuring.

  According to the third aspect of the present invention, an engine valve made of a titanium alloy containing aluminum in which a heat-resistant steel chip is brazed to the tip of the shaft end can be manufactured relatively easily.

  According to the invention described in claim 4, in addition to the effect of the invention described in claim 3, brazing is quickly performed simultaneously with quenching of the heat-resistant steel tip to the shaft end portion without oxidation and the like. The manufacturing time can be shortened.

  According to the invention described in claim 5, in addition to the effect of the invention described in claim 3 or 4, quenching is performed simultaneously with brazing of the heat-resistant steel chip, and the structure of at least the surface of the shaft end portion and the groove portion, etc. The engine valve quality can be improved.

  According to the invention of claim 6, brazing and quenching of the heat-resistant steel chip and optimization of at least the surface structure of a part of the shaft part, the groove part and the shaft end part can be performed at the same time. The manufacturing time can be shortened.

  According to the seventh aspect of the invention, in addition to the effect of the sixth aspect of the invention, there is no oxidation and the brazing is quickly performed simultaneously with the quenching of the heat-resistant steel tip to the shaft end portion. The manufacturing time can be shortened.

  According to the invention described in claim 8, in addition to the effect of the invention described in claim 6 or 7, in addition to quenching of the heat-resistant steel chip, brazing and optimization of at least the surface structure such as the shaft end and groove And the quality of the engine valve can be improved.

  Hereinafter, an embodiment of an engine valve and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a front view of an engine valve 1 of this embodiment. The engine valve 1 is used as an intake valve or an exhaust valve of an engine, and includes a shaft portion 2, an umbrella portion 3 formed at one end (base end) of the shaft portion 2, and other portions of the shaft portion 2. A groove portion 4 and a shaft end portion 5 formed at the end (tip) are provided. Said structure parts 2-5 are formed of the titanium alloy containing aluminum. The shaft end portion 5 of this embodiment is shorter than the shaft end portion 35 (see FIG. 7) in the engine valve 31 of the conventional example. A hardenable heat-resistant steel tip 6 is heated and brazed to the tip of the shaft end portion 5. That is, the heat-resistant steel tip 6 is joined to the tip of the shaft end portion 5 via the brazing material 7.

  In FIG. 2, the front-end | tip part of the engine valve 1 containing the front-end | tip part of the axial part 2, the groove part 4, the axial end part 5, and the heat-resistant steel chip | tip 6 is expanded and shown. In FIG. 2, the differences between the constituent parts 2 to 7 are shown in different patterns. In this embodiment, a part of the shaft part 2, at least the surface of the groove part 4 and the shaft end part 5 is composed of an equiaxed structure (α + β) or a solution structure (β) indicated by a group of diagonal lines rising to the right in FIG. The Further, the part other than a part of the shaft part 2 and the umbrella part 3 are constituted by a needle-like structure (α + β) indicated by a group of diagonal lines that are downwardly inclined in FIG. That is, the portion formed of the titanium alloy is constituted by an equiaxed structure (α + β) or a solution structure (β) and a needle-like structure (α + β). Here, in FIGS. 1 and 2, the brazing material 7 is illustrated in layers so that it can be distinguished from the others, but in reality, the brazing material 7 is interdiffused at the time of joining, so that it remains as a layer as illustrated. Absent. In FIG. 2, at least the surface that is a part of the shaft portion 2 and is in the range of at least 1 to 10 mm from the lower end of the groove portion 4 is composed of an equiaxed tissue (α + β) or a solution structure (β).

  FIG. 3 is a table showing differences in composition, β transformation point, surface treatment / heat treatment for each part (heat-resistant steel tip, other part (titanium valve)) of the engine valve 1 in this embodiment. FIG. 4 is a table showing differences in composition, solidus line, liquidus line, and brazing temperature example for an example of the brazing material 7 in this embodiment.

  Also in the engine valve 1 of this embodiment, as shown in FIG. 8, a spring retainer is provided in the groove portion 4 via a cotter, and a valve spring made of a compression spring is provided between the cylinder head and the retainer. . As a result, an upward biasing force is applied to the groove portion 4 by the valve spring.

  Next, a method for manufacturing the engine valve 1 will be described. FIG. 5 is a flowchart showing the manufacturing process of the engine valve 1. Description will be made sequentially along the numbers assigned to this flowchart.

(1) A shaped material is prepared.
(2) Hot forging is performed on the base material. By this forging, a workpiece having a basic shape including the shaft portion 2, the umbrella portion 3, the groove portion 4, and the shaft end portion 5 shown in FIG.
(3) A first heat treatment is performed on the workpiece after hot forging. By this heat treatment, the entire surface of the workpiece is formed into a needle-like structure (α + β). This first heat treatment corresponds to the first heating step in the present invention (Claim 6). The first heat treatment may also serve as a cooling step after hot forging.
(4) The workpiece is machined. By this processing, the outer shape of the workpiece is adjusted.
(5) The workpiece surface is oxidized.
(6) The end surface of the shaft end is processed. This processing is a preparation for facilitating brazing of the heat-resistant steel chip to the end face of the shaft end portion later by removing the oxide layer.
(7) A heat-resistant steel tip is brazed to the end face of the shaft end. This brazing is performed in a plurality of steps. First, the heat-resistant steel chip is pressed and held on the end face of the shaft end portion by an appropriate load with a brazing material interposed therebetween or by the weight of the heat-resistant steel chip. This pressing and holding corresponds to the pressing and holding step in the present invention (Claim 6). Next, a second heat treatment is performed for a predetermined portion, and then a rapid cooling process is performed for the predetermined portion.

  Here, the second heat treatment is performed as follows. As shown in FIG. 6, an induction heating coil 11 surrounds the periphery of the tip portion including a part of the shaft portion 2, the groove portion 4, the shaft end portion 5, and the heat-resistant steel tip 6. And the above-mentioned front-end | tip part is high-frequency induction-heated by operating the coil 11 for a predetermined time in a vacuum or in an inert atmosphere. As shown in FIG. 6, the heating of the second heat treatment is performed in the range of at least 1 to 10 mm from the upper end of the heat-resistant steel tip 6, which is the shaft portion 5 and from the end of the groove portion 4. The heating and holding temperature at this time is β transformation point −100 to + 100 ° C., not less than the liquidus of the brazing material, and not less than the quenching temperature of the heat-resistant steel chip, and the heating and holding time is 1 to 10 minutes. It is. By this second heat treatment, the heat-resistant steel tip 6, the shaft end 5, the groove 4, and a part of the surface of the shaft 2 are heated, and the heat-resistant steel tip 6 is brazed to the tip of the shaft end 5 and quenched. In addition, at least the surfaces of the shaft end portion 5, the groove portion 4, and the shaft portion 2 are set to be equiaxial structure (α + β) or solution structure (β). This second heat treatment corresponds to the second heating step in the present invention (Claim 6). The rapid cooling process described above is performed by cooling the heating range with water, oil, liquid nitrogen, dry ice, or the like. This rapid cooling process corresponds to the rapid cooling process in the present invention (Claim 6).

(8) Workpiece finishing is performed. That is, the dimension is secured after the second heat treatment.
(9) The second heat treatment portion is subjected to surface treatment using plating or the like. However, this surface treatment needs to be performed at a treatment temperature that does not affect the structure (for example, several tens of degrees C. in the case of plating).
(10) The engine valve is completed through the above steps.

  According to the engine valve 1 of this embodiment described above, since the heat-resistant steel tip 6 is brazed to the tip of the shaft end portion 5, the shaft end portion 5 comes into contact with a member such as a rocker arm via the heat-resistant steel tip 6. Will do. In addition, since the heat-resistant steel tip 6 is located on the opposite side of the shaft portion 2 with the groove portion 4 interposed therebetween, even if the urging force of the valve spring acts on the groove portion 4, the brazed portion of the heat-resistant steel tip 6 is affected. There is no. For this reason, compared with the conventional engine valve 31, the abrasion resistance of the shaft end portion 5 of the engine valve 1 can be improved, and the fatigue strength in the vicinity of the shaft end portion 5 and the groove portion 4 can be improved. For this reason, especially when the runout of the shaft portion 2 of the engine valve 1 becomes large during high-speed rotation of the engine or the like, fatigue failure in the vicinity of the shaft end portion 5 and the groove portion 4 can be effectively suppressed. It becomes like this.

  According to the engine valve 1 of this embodiment, a part of the shaft part 2, at least the surfaces of the groove part 4 and the shaft end part 5 are composed of equiaxed tissue (α + β) or solution structure (β). The fatigue crack growth rate is slow. In this sense, the fatigue strength in the vicinity of the shaft end portion 5 and the groove portion 4 can be further increased. Moreover, since the part other than a part of the shaft part 2 and the umbrella part 3 are composed of a needle-like structure (α + β), the distortion of the part with respect to high temperature is small. For this reason, the fatigue strength in the vicinity of the groove 4 can be increased while ensuring the heat resistance equivalent to that of a conventional titanium alloy engine valve.

  Further, in the engine valve 1 of this embodiment, at least the surface in the range of at least 1 to 10 mm from the end of the groove 4 that is a part of the shaft portion 2 is composed of equiaxed tissue (α + β) or solution-treated tissue (β). Therefore, the fatigue crack growth rate becomes slow in the optimum range for a part of the shaft portion 2 adjacent to the groove portion 4. For this reason, high fatigue strength can be obtained even at the connecting portion between the groove portion 4 and the shaft portion 2, and the durability of the engine valve 1 can be enhanced.

  According to the engine valve manufacturing method of this embodiment, the heat-resistant steel tip 6 that can be hardened is brazed to the tip of the shaft end portion 5 by heating, so that the heat-resistant steel tip 6 is attached to the tip of the shaft end portion 5. Can be joined relatively easily. For this reason, the engine valve 1 made of a titanium alloy containing aluminum in which a heat-resistant steel tip 6 is brazed to the tip of the shaft end portion 5 can be manufactured relatively easily.

  According to the method for manufacturing an engine valve in this embodiment, a part of the shaft portion 2, at least the surfaces of the groove portion 4 and the shaft end portion 5, and the heat-resistant steel tip 6 are subjected to high-frequency induction heating in a vacuum or in an inert atmosphere. Since it is cooled rapidly after the heating, high-quality brazing and quenching of the heat-resistant steel tip 6 to the shaft end portion 5 is performed in a short time. For this reason, the manufacturing time of the engine valve 1 can be shortened.

  According to the method for manufacturing an engine valve in this embodiment, the heat-resistant steel tip 6 is suitably brazed to the shaft end portion 5 and quenched at the same time. Furthermore, an equiaxed structure (α + β) or a solution structure (β) is formed on at least the surfaces of the shaft portion 2, the groove portion 4, and the shaft end portion 5, and a portion other than a portion of the shaft portion 2 and an umbrella Part 3 maintains a needle-like tissue (α + β). For this reason, brazing of the heat-resistant steel tip 6 and optimization of at least the surface structure of a part of the shaft part 2, the groove part 4 and the shaft end part 5 can be performed at the same time. Time can be shortened.

  According to the method for manufacturing an engine valve in this embodiment, an equiaxed structure (α + β) or a solution structure (β) is formed on at least the surface of a part of the shaft part 2 and at least 1 to 10 mm from the end of the groove part 4. Is formed. For this reason, the fatigue strength can be increased in an appropriate range in the vicinity of the groove portion 4, particularly on the shaft portion 2 side.

  In the second heat treatment described above, the heat holding temperature is β transformation point −100 to + 100 ° C., the liquidus of the brazing material or more, and the heat treatment steel chip quenching temperature or more, and the heat holding time. Is set to 1 to 10 minutes, the brazing of the heat-resistant steel tip 6 and the optimization of at least the surface structure such as the shaft end 5 and the groove 4 can be achieved. For this reason, the quality of the engine valve 1 can be improved.

  In addition, this invention is not limited to the said embodiment, A part of structure can also be changed suitably and implemented in the range which does not deviate from the meaning of invention.

  For example, in the above-described embodiment, the heat resistant steel tip 6 is brazed to the tip of the shaft end portion 5 for the engine valve 1 made of a titanium alloy containing aluminum, and a part of the shaft portion 2, the groove portion 4 and the shaft end are also brazed. At least the surface of the portion 5 was composed of equiaxed tissue (α + β) or solution-treated tissue (β), and the portion other than a part of the shaft portion 2 and the surface of the umbrella portion 3 were composed of needle-like tissue (α + β). On the other hand, the above configuration may be embodied in an engine valve in which the equiaxed structure (α + β) or the solution structure (β) and the needle-like structure (α + β) are omitted, and a method for manufacturing the engine valve.

  Further, in the engine valve manufacturing method according to the above embodiment, during the series of manufacturing steps, after the “work finish processing”, the “second surface treatment” is subjected to “surface treatment” using plating or the like. “Surface treatment” may be omitted.

The front view which concerns on one Embodiment and shows an engine valve. The enlarged view which shows the structure of the front-end | tip part of an engine valve. A table showing specifications of each part of the engine valve. Table showing specifications of brazing material. The flowchart which shows the manufacturing process of an engine valve. Explanatory drawing which shows the process of 2nd heat processing. The front view which shows the engine valve of a prior art example. Sectional drawing which shows the use condition of an engine valve front-end | tip part. The front view which shows the engine valve front-end | tip part of a prior art example. The front view which shows the engine valve front-end | tip part of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine valve 2 Shaft part 3 Umbrella part 4 Groove part 5 Shaft end part 6 Heat-resistant steel chip 7 Brazing material

Claims (8)

An engine valve having a shaft portion, an umbrella portion formed at one end of the shaft portion, a groove portion and a shaft end portion formed at the other end of the shaft portion, and formed of a titanium alloy containing aluminum. And
An engine valve characterized in that a heat-resistant steel tip is brazed to the tip of the shaft end. At least surfaces of a part of the shaft part, the groove part, and the shaft end part are composed of an equiaxed structure or a solution structure, and a part other than a part of the shaft part and the umbrella part are composed of a needle-like structure. The engine valve according to claim 1. Manufacture of an engine valve comprising a shaft portion, an umbrella portion formed at one end of the shaft portion, a groove portion and a shaft end portion formed at the other end of the shaft portion, and formed of a titanium alloy containing aluminum A method,
Heating a part of the shaft part, at least the surface of the groove part and the shaft end part and a heat-resistant steel chip that can be hardened, and brazing the heat-resistant steel chip to the tip of the shaft end part by the heating. A method for manufacturing an engine valve. The heating of a part of the shaft part, at least the surface of the groove part and the shaft end part, and the heat-resistant steel tip is high-frequency induction heating performed in a vacuum or under an inert atmosphere for a predetermined time, and after that heating, rapid cooling The method of manufacturing an engine valve according to claim 3. The heat holding temperature of at least the surface of a part of the shaft part, the groove part and the shaft end part and the heat-resistant steel chip is a β transformation point of −100 to + 100 ° C. and a liquidus of the brazing material or more, and 5. The method for manufacturing an engine valve according to claim 3, wherein the temperature is equal to or higher than a quenching temperature of the heat-resistant steel chip, and the heating and holding time is 1 to 10 minutes. Manufacture of an engine valve comprising a shaft portion, an umbrella portion formed at one end of the shaft portion, a groove portion and a shaft end portion formed at the other end of the shaft portion, and formed of a titanium alloy containing aluminum A method,
A first heating step in which the shaft portion, the umbrella portion, the groove portion, and the shaft end portion are heated to form a needle-like tissue as a whole;
A step of pressing and holding a heat-resistant steel chip that can be hardened through a brazing material at the tip of the shaft end with an appropriate load;
The heat-resistant steel tip, the shaft end portion, the groove portion, and a part of the shaft portion are heated to braze the heat-resistant steel tip to the tip of the shaft end portion, and the shaft end portion, the groove portion, and A second heating step in which at least the surface of a part of the shaft portion has an equiaxed structure or a solution structure;
A method of manufacturing an engine valve, comprising: a rapid cooling step of rapidly cooling the heated portion immediately after the second heating step. The method for manufacturing an engine valve according to claim 6, wherein the second heating step is high-frequency induction heating performed in a vacuum or under an inert atmosphere for a predetermined time. The heating and holding temperature in the second heating step is β transformation point −100 to + 100 ° C., not less than the liquidus of the brazing material, and not less than the quenching temperature of the heat-resistant steel chip, and the heating and holding time is It is 1 to 10 minutes, The manufacturing method of the engine valve of Claim 6 or 7 characterized by the above-mentioned.

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