WO2020235603A1

WO2020235603A1 - Engine valve and method for manufacturing same

Info

Publication number: WO2020235603A1
Application number: PCT/JP2020/019982
Authority: WO
Inventors: 水野芳伸; 伊藤誠
Original assignee: Ｅｃｏ－Ａ株式会社
Priority date: 2019-05-21
Filing date: 2020-05-20
Publication date: 2020-11-26
Also published as: CN113891774A; JPWO2020235603A1

Abstract

The purpose of the present invention is to provide an engine valve and a method for manufacturing the same, the engine valve in which: deburring and the like are unnecessary; the strength of a joining part is high; and deterioration of a metal structure other than the joining part is low. This method for manufacturing an engine valve formed of a first member 11 and a second member 12 joined with each other involves joining a joining surface of the first member 11 and a joining surface of the second member 12 through electric diffusion joining. Accordingly, it is possible to provide an engine valve in which the first member 11 and the second member 12 are joined with each other with 5 μm or less of a diffusion layer 13 therebetween.

Description

Engine valve and its manufacturing method

The present invention relates to an engine valve and a method for manufacturing the same.

In recent years, from the viewpoint of global environmental issues and energy saving, it has been required more than ever to reduce the weight of internal combustion engines, especially automobile engines, and to operate the engines efficiently at higher combustion temperatures.

In order to operate the engine efficiently at a higher combustion temperature, it is necessary to construct the engine parts with heat-resistant structural materials, and to use a lightweight part shape or structure that does not accumulate excessive heat.

In particular, engine parts that operate under harsh conditions, such as engine valves that reciprocate at high speed while being exposed to high temperatures, have excellent shapes such as weight reduction, heat capacity reduction, heat dissipation and heat resistance improvement. Structure is needed.

For that reason, various engine valves are provided, such as making them hollow, or enclosing metallic sodium in a hollow shaft to reduce the heat load.

In addition, each member such as the valve head, valve face, valve stem, and valve stem end that make up the engine valve is manufactured individually according to each purpose such as weight reduction, reduction of heat capacity, improvement of heat dissipation and heat resistance. After that, an engine valve as a finished product is manufactured by joining each member to each other (for example, Patent Document 1).

JP-A-2004-25198

Conventionally, friction welding or the like has been used for joining these members. However, in friction welding, as shown in FIG. 4, burrs that cannot be ignored occur in the joint portion 1413, so a deburring step is indispensable in post-processing. Further, in the case of a hollow member, burrs will remain inside. However, burrs are a kind of defect and have problems such as lowering the fatigue resistance of the engine valve. Further, it is not preferable in terms of mechanical characteristics that burrs remain in the invisible portion. Therefore, joining by diffusion joining is also performed. However, in the conventional diffusion bonding, since the diffusion bonding is performed at the ambient temperature in the vacuum furnace, the entire component may reach the diffusion temperature and the metal structure of the entire component may be deteriorated.

Therefore, an object of the present invention is to provide an engine valve which does not require deburring, has high strength of the joint portion 14, and has little deterioration of the metal structure other than the joint portion, and a method for manufacturing the engine valve.

In order to achieve the above object, the engine valve of the present invention has a first member and a second member joined to each other, and the first member and the second member are interposed via a diffusion layer within 5 μm. It is characterized by being joined together.

In this case, it may have a hollow portion that communicates the first member and the second member.

Further, the shape of the diffusion layer is preferably formed in a convex shape on at least one of the first member and the second member, and is preferably one of the first member and the second member. It is better to have one formed in a convex shape on the side with higher electrical resistance.

The first member is made of a first metal, and the second member can be made of a second metal made of a material different from that of the first member.

Further, the method for manufacturing an engine valve of the present invention is a method for manufacturing an engine valve composed of a first member and a second member joined to each other, and the joint surface of the first member and the second member are subjected to current diffusion joining. It is characterized in that the joint surfaces of the above are joined.

In this case, it is preferable that at least one of the first member and the second member has a convex joint surface, and preferably, the first member and the second member having the lower electric resistance are joined. It is better to make the surface convex.

Further, it is preferable that the energization diffusion joint energizes the joint surface between the first member and the second member by controlling the output of the power supply with an upslope.

Further, in the energization diffusion joining, the time for energizing the first member and the second member is preferably 90 seconds or less, preferably 30 seconds or less.

Further, the first member may be made of a first metal, and the second member may be made of a second metal whose material is different from that of the first member.

Further, the diffusion bonding may be one in which the bonding surface between the first metal and the second metal is energized and diffusion bonding is performed in a solid phase by the resistance heat generation thereof, or diffusion bonding is performed in a liquid phase. There may be.

According to the engine valve of the present invention, since the joint portion 14 is joined by current diffusion joint, there is little deterioration of the metal structure other than the joint portion 14. Moreover, the strength of the joint portion 14 is very high.

It is a side view which shows the engine valve of this invention. It is a side view and a partially enlarged view which shows the state before joining of the engine valve of this invention. It is a side view and a partially enlarged view which shows the engine valve of this invention. It is a side view which shows the engine valve which joined by friction welding welding.

The engine valve 1 of the present invention will be described with reference to FIGS. 1 to 3. As shown in FIG. 1, the engine valve 1 of the present invention has at least a first member 11 and a second member 12 joined to each other. Here, the first member 11 and the second member 12 may be any combination as long as they are members constituting the engine valve 1 and are joined to each other. For example, there are combinations of a valve head and a valve face, a valve face and a valve stem, a valve stem and a valve stem end, and the like. In FIG. 1A, the first member 11 is a valve face and the second member 12 is a valve stem. Further, in FIG. 1B, the first member 11 is a valve stem and the second member 12 is a valve stem end. Further, the engine valve 1 may have three or more joined members.

The first member 11 and the second member 12 are joined via a diffusion layer 13 within 5 μm. By setting the diffusion layer 13 within 5 μm, it is possible to provide an engine valve having a high strength of the joint portion 14 while maintaining the function of each member with less deterioration of the metal structure other than the joint portion 14. In the bonding, the thickness of the diffusion layer 13 should be 5 μm or less, preferably 3 μm or less, and more preferably 1 μm or less. The joining method may be any method as long as the thickness of the diffusion layer 13 can be 5 μm or less, and for example, an energization diffusion joining described later can be used.

When using a current diffusion junction, it is necessary to control the current flow. Therefore, at least one of the joint surface 11a of the first member 11 and the joint surface 12a of the second member 12 before joining is made convex, and first contact with a point or a line, and when an electric current is applied, a diffusion layer is gradually formed. A shape in which 13 is spread and joined is preferable. In this case, the other joint surface preferably has a smooth shape such as a flat surface or a mirror surface so that at least no voids are formed during diffusion bonding. For example, as shown in FIG. 2, as the shape of the joint surface 11a of the first member 11 and the joint surface 12a of the second member 12 before joining, one is formed in a convex shape and the other is formed in a flat shape. be able to. By joining in this way, the diffusion layer 13 gradually and neatly spreads from the apex of the convex portion in contact with the plane, so that a uniform diffusion layer 13 can be formed. Therefore, the breaking strength of the joint portion 14 can be increased. Of course, it is also possible to make both the joint surface 11a and the joint surface 12a convex.

Further, since a member having a high electric resistance is more likely to generate heat, it is easier to form a uniform diffusion layer by making the joint surface of the first member 11 and the second member 12 having a lower electric resistance convex. ..

The convex shape of the joint surface means that the tip of the joint surface is point-shaped or linear, and for example, the joint surface may be conical or spherical, or the cross section of the joint surface may be triangular or arch-shaped. be able to. Further, only one convex portion may be formed on the joint surface, or a plurality of convex portions may be formed. When a plurality of convex portions are formed on the joint surface, conventionally known methods such as sand blast treatment, shot blast treatment, etching treatment, and laser treatment can be used.

When the first member 11 and the second member 12 formed in this way are joined, the shape of the diffusion layer 13 is either the first member 11 or the second member 12 at the joint portion 14, as shown in FIG. It will have a convexly formed portion on one side. More preferably, as described above, the first member 11 and the second member 12 having a convex joint surface having a lower electric resistance and a flat joint surface having a higher electric resistance are joined. It is a shape formed in the case, and specifically, it is preferable that the shape of the diffusion layer 13 is formed to be convex toward the higher electrical resistance of the first member 11 and the second member 12. The number of convex portions formed on the diffusion layer 13 may be plural.

Further, the first member 11 and the second member may have any shape as long as they can exert the functions of the respective members, and a conventionally known general shape can be adopted. For example, the first member 11 and the second member 12 may have a hollow portion 15 that communicates with each other. The hollow portion 15 is a portion whose inside is hollow for the purpose of reducing the weight of the engine valve 1 and reducing the heat capacity.

Also, the material of the first member 11 is made of metal (first metal). The first member 11 may be any metal as long as it can exhibit the function of the member, and for example, steel materials such as austenitic stainless steel and martensitic stainless steel, nickel alloys, titanium and titanium alloys may be used. it can. Specific examples include SUH3 as a material for the valve face (first member 11).

Further, the material of the second member 12 is made of a metal (second metal) whose material is different from that of the first member 11. For example, steel materials such as austenitic stainless steel and martensitic stainless steel, nickel alloys, titanium and titanium alloys can be used. Further, the metals having different materials include not only metals having different components but also metals having the same components but different properties such as metals formed by different quenching. When the first member 11 and the second member 12 are made of the same type of metal, there is an advantage that the bonding interface is hardly seen and the fracture strength is superior to that of the conventional friction welding. As a specific example, when SUH3 is used as the material of the valve face (first member 11), SUH35 can be used as the valve stem (second member 12).

Next, the manufacturing method of the engine valve 1 of the present invention will be described. The method for manufacturing the engine valve 1 of the present invention is to join the joint surface 11a of the first member 11 and the joint surface 12a of the second member 12 described above by current diffusion joining.

Here, the energization diffusion bonding is a method in which the bonding surface of the first member 11 and the second member 12 is energized and diffusion bonding is performed in a solid phase or a liquid phase by the heat generation of the resistance. The current diffusion bonding has an advantage that the deformation of the bonding portion 14 between the first member 11 and the second member 12 is small and precise bonding is possible. It also has the advantage that there is almost no alteration of the metal structure other than the joint portion 14.

When using a current diffusion junction, it is necessary to control the current flow. Therefore, at least one of the joint surface 11a of the first member 11 and the joint surface 12a of the second member 12 before joining is made convex, and first contact with a point or a line, and when an electric current is applied, a diffusion layer is gradually formed. A shape in which 13 is spread and joined is preferable. In this case, the other joint surface preferably has a smooth shape such as a flat surface or a mirror surface so that at least no voids are formed during diffusion bonding. For example, as shown in FIG. 2, as the shape of the joint surface 11a of the first member 11 and the joint surface 12a of the second member 12 before joining, one is formed in a convex shape and the other is formed in a flat shape. be able to. By joining in this way, the diffusion layer 13 gradually and neatly spreads from the apex of the convex portion in contact with the plane, so that an even and uniform diffusion layer 13 can be formed. Therefore, the breaking strength of the joint portion 14 can be increased. Of course, it is also possible to make both the joint surface 11a and the joint surface 12a convex.

When the first member 11 and the second member 12 formed in this way are joined, the shape of the diffusion layer 13 is either the first member 11 or the second member 12 at the joint portion 14, as shown in FIG. It will have a convexly formed portion on one side. More preferably, as described above, the joint surface of the first member 11 and the second member 12 having the lower electric resistance is convex and the joint surface having the higher electric resistance is flat. It is a shape formed in the case, and specifically, it is preferable that the shape of the diffusion layer 13 is formed to be convex toward the higher electrical resistance of the first member 11 and the second member 12. The number of convex portions formed on the diffusion layer 13 may be plural.

For the energization diffusion bonding, for example, the following energization diffusion bonding device can be used. The energization diffusion joining device is for performing diffusion bonding by energizing the first member 11 and the second member 12 with which the joint surfaces are abutted, and is an electrode, a power source, a temperature information providing unit, and an output control unit. And a pressurizing part.

The electrodes are for conducting electricity output from the power supply to the first member 11 and the second member 12. The energization diffusion joining device may be provided with at least two electrodes for conducting electricity to the first member 11 and the second member 12, for example, sandwiching the joining surface between the first member 11 and the second member 12. It is provided in the opposite part with. Of course, three or more electrodes may be provided depending on the material and shape of the first member 11 and the second member 12. The electrode may be made of any material as long as electricity can be conducted through the first member 11 and the second member 12, and for example, copper, molybdenum, tungsten, or the like can be used. Also, the electrodes are connected to the power supply via a cable.

The power supply is for outputting power to multiple electrodes. The power supply may be any power supply as long as the outputs applied to the plurality of electrodes can be continuously changed, and for example, a known inverter power supply can be used.

The temperature information providing unit is for providing the output control unit with temperature information of the first member 11 and the second member 12 or the electrodes. The temperature information means information on the temperature of the first member 11 and the second member 12 or the electrode, and may be the information as it is, or is calculated from the temperature such as the voltage value that determines the voltage of the power supply. It may be the information converted by. As the temperature information providing unit, for example, a temperature sensor that detects the temperature of the first member 11, the second member 12, or the electrode can be used. The temperature sensor may be any one as long as it can detect the temperature of the joint 14 material or the electrode. For example, a non-contact sensor that detects the temperature in a non-contact manner such as an infrared radiation thermometer, or a first member 11 A contact type sensor such as a thermocouple that detects the temperature by contacting the second member 12 or the electrode may be used. It is also possible to use both a non-contact type and a contact type.

Here, it is preferable that the energization diffusion joint according to the present invention energizes the joint surface of the first member 11 and the second member 12 by controlling the output of the power supply with an upslope. Therefore, it is preferable that the output control unit controls the output of the power supply with an upslope based on the temperature information from the temperature information providing unit. Conventionally, a constant current is energized for a certain period of time, or a constant current is energized by ON / OFF control, so that the temperature of the place where the current is concentrated may rise sharply. In this case, the bonding state of the bonding surface becomes non-uniform, such as the bonding state of the relevant portion becoming a liquid phase bond, which leads to variations in the bonding state. On the other hand, in the upslope control, since the current is gradually increased, sudden current concentration can be suppressed and the temperature of the joint surface can be made uniform. Therefore, it is possible to grow a uniform diffusion layer 13 on the joint surface, and it is possible to achieve uniform strength. In particular, as described above, when one of the joint surface 11a of the first member 11 and the joint surface 12a of the second member 12 before joining is formed to be convex and the other is flat. This is because the concentration of electric current can be suppressed and a more uniform diffusion layer 13 can be grown.

In addition, the output control unit can continuously control the output of the power supply in real time with an upslope based on the temperature information detected by the temperature sensor, enabling precise temperature control of the first member 11 and the second member 12. it can. Therefore, the joining strength of the 14 joining portions on the joining surface is high, and it is possible to perform joining with little variation. Further, such continuous control can maintain a constant thermal expansion as compared with ON / OFF control, so that the influence of pressure fluctuation due to thermal expansion can be reduced.

The output control unit may be any as long as the output of the power supply can be controlled by an upslope based on the temperature information from the temperature information providing unit. For example, from the CPU, ROM, RAM, I / O, etc. It is possible to use the one which is configured and the operation unit and the display unit are electrically connected. Specifically, a known PID temperature controller such as a high-speed sampling temperature controller can be used. The operation unit is composed of various operation switches such as a start switch and a start switch, an input panel including a touch panel, and the like. The information input from the operation unit is transmitted to the output control unit. Further, the display unit receives information based on the input to the output control unit or the calculation result in the output control unit from the output control unit, and displays the information. Here, the display unit is composed of a digital display panel, a lamp, and the like.

In the temperature information providing unit described above, the temperature of the first member 11 and the second member 12 or the electrode is acquired in real time by using the temperature sensor, and the output control unit of the first member 11 and the second member 12 or the electrode The case of providing temperature information has been described. However, when the first member 11 and the second member 12 of the same material are joined in the same environment using the current diffusion joining device, the relationship between the elapsed time and the temperature of the first member 11 and the second member 12 or the electrode is the same. The result is. Therefore, if the temperature information indicating the relationship between the elapsed time and the temperature of the first member 11 and the second member 12 or the electrode is acquired in advance, the temperature information can be provided without using the temperature sensor. .. Therefore, the temperature information providing unit is a temperature information storage unit that stores temperature information indicating the relationship between the elapsed time of the first member 11 and the second member 12 or the electrode and the temperature of the first member 11 and the second member 12 or the electrode. It may be. As a result, the output control unit can control the output of the power supply based on the temperature information stored in the temperature information storage unit. The temperature information storage unit may be any as long as it can store the temperature information for determining the relationship between the elapsed time and the output of the power supply, and for example, a known memory or the like may be used.

The pressurizing portion is for applying pressure to the joint surface between the first member 11 and the second member 12. The structure of the pressurizing portion may be any as long as pressure can be applied to the joint surface between the first member 11 and the second member 12, but for example, the pressurizing member to which the electrodes are fixed and the pressurizing member are driven. It may be composed of a drive source for the purpose and a ball screw mechanism that transmits the driving force of the drive source and moves the pressurizing member up and down.

The pressurizing member may be formed according to the shapes of the first member 11 and the second member 12, or an intermediate member matching the shapes of the first member 11 and the second member 12 may be sandwiched between them. The material of the pressure member may be any material as long as it has rigidity against pressure, and for example, a metal such as stainless steel, copper, molybdenum, or tungsten may be used.

The pressurizing member may have a cooling means for cooling the first member 11 and the second member 12. The cooling means may be any one as long as the first member 11 and the second member 12 can be cooled, and for example, a cooling fluid such as tap water may be circulated in the flow path. .. The flow path may be provided on the pressurizing member itself, or a cooling block on which the flow path is formed may be arranged in close contact with the pressurizing member.

As the drive source, for example, a servomotor with a speed reducer can be used. An encoder is attached to the servomotor and is arranged on a gantry.

The ball screw mechanism consists of a screw shaft extending in the vertical direction and having a thread groove formed on the outer peripheral surface, a nut having a thread groove formed on the inner peripheral surface, and a plurality of balls accommodated between these thread grooves. Has been done. The nut is fixed to the upper part of the pressurizing member via an insulator made of bakelite or the like and a pressure sensor. The screw shaft is connected to the rotating shaft of the servomotor via a speed reducer. When the servomotor is rotationally driven, the screw shaft rotates, and the nut, and thus the pressurizing member, moves up and down relative to the screw shaft. Further, when the driving of the servomotor is stopped, the position of the pressurizing member is maintained. At this time, the pressurizing portion regulates the displacement of the first member 11 and the second member 12 to apply pressure to the joint surface.

Further, the pressurizing unit may have a pressure sensor that detects the pressure on the joint surface. The pressure sensor is, for example, a uniaxial load cell that measures the pressure in the vertical direction, but a multi-axis pressure sensor may be used. The pressure sensor can indirectly detect the pressure applied to the joint surface between the first member 11 and the second member 12.

Further, the pressurizing portion may further include an elastic force urging means for urging the joint surface between the first member 11 and the second member 12. For example, an elastic force urging means is arranged between the base member on which the pressurizing member is arranged and the base of the current diffusion joining device. The elastic force urging means is composed of, for example, a spring and a block body for restricting the spring to a preset length shorter than the free length between the spring and the base member. The pressure acting on the first member 11 and the second member 12 from the base member pushed up by the elastic force urging means can be changed by exchanging the spring. With this configuration, even if thermal expansion or contraction occurs in the first member 11 and the second member 12, a sudden change in pressure acting on the joint surface can be alleviated.

Although the above-described configuration has been described as the pressurizing portion, the pressurizing portion may have any other configuration as long as it is for pressing the first member 11 and the second member 12 with each other at the joint surface. For example, it is also possible to simply put a weight on the first member 11 and the second member 12 and press the first member 11 and the second member 12 against each other.

Further, the energization heating joining device may further have a pressure control unit for controlling the pressure applied to the joining surface. The pressure control unit is composed of, for example, a CPU, ROM, RAM, I / O, etc., and the operation unit and the display unit are electrically connected to each other. Here, the operation unit is composed of various operation switches such as a start switch and a start switch, an input panel including a touch panel, and the like. The information input from the operation unit is transmitted to the pressure control unit. Further, the display unit receives information from the pressure control unit based on the input to the pressure control unit or the calculation result in the pressure control unit, and displays the information. Here, the display unit is composed of a digital display panel, a lamp, and the like. It is also possible to use the same pressure control unit as the output control unit described above.

Further, detection signals are input to the pressure control unit from the encoder, the pressure sensor and the temperature sensor. The pressure control unit is based on these detection signals, information input from the operation unit, and control information such as set pressure Ps, lower limit set pressure Ps1, set temperature Ts, and set holding time Hs stored in the storage unit. Outputs a control signal to the servo motor.

As described above, in the diffusion bonding using the current diffusion bonding device, the bonding surface 11a of the first member 11 and the bonding surface 12a of the second member 12 are brought into contact with each other, and the first member 11 and the second member 12 are energized. Heat. As a result, the diffusion layer 13 can be grown and joined to the joint surface between the first member 11 and the second member 12. In addition, in order to prevent the structural change of the metal of the first member 11 and the second member 12 as much as possible, the energization time is preferably 90 seconds or less, and more preferably 30 seconds or less. As a result, the thickness of the diffusion layer 13 of the first member 11 and the second member 12 can be reduced to 5 μm or less.

1: Engine valve
11: First member
11a: Joint surface
12: Second member
12a: Joint surface
13: Diffusion layer
14: Joint
15: Hollow part

Claims

An engine valve having a first member and a second member joined to each other.
An engine valve characterized in that the first member and the second member are joined via a diffusion layer within 5 μm.
The engine valve according to claim 1, further comprising a hollow portion that communicates the first member and the second member.
The engine valve according to claim 1 or 2, wherein the shape of the diffusion layer is formed in a convex shape on at least one of the first member and the second member.
The engine valve according to claim 3, wherein the shape of the diffusion layer is formed in a convex shape on the side of the first member and the second member having a higher electric resistance.
The engine valve according to any one of claims 1 to 4, wherein the first member is made of a first metal, and the second member is made of a second metal having a material different from that of the first member.
It is a method of manufacturing an engine valve composed of a first member and a second member joined to each other.
A method for manufacturing an engine valve, which comprises joining a joint surface of the first member and a joint surface of the second member by current diffusion joining.
The method for manufacturing an engine valve according to claim 6, wherein the joint surface of at least one of the first member and the second member is convex.
The method for manufacturing an engine valve according to claim 7, wherein the joint surface of the first member and the second member having the lower electric resistance is convex.
The method according to any one of claims 6 to 8, wherein the energization diffusion joint energizes the joint surface between the first member and the second member by controlling the output of a power source with an upslope. How to manufacture an engine valve.
The method for manufacturing an engine valve according to any one of claims 6 to 9, wherein in the current-carrying diffusion joint, the time for energizing the first member and the second member is 90 seconds or less.
The method for manufacturing an engine valve according to any one of claims 6 to 9, wherein in the current-carrying diffusion joint, the time for energizing the first member and the second member is 30 seconds or less.
The manufacture of an engine valve according to any one of claims 6 to 11, wherein the first member is made of a first metal, and the second member is made of a second metal whose material is different from that of the first member. Method.
The invention according to any one of claims 6 to 12, wherein the diffusion bonding is such that the bonding surface between the first metal and the second metal is energized and diffusion bonding is performed in a solid phase by heat generation of resistance thereof. How to make an engine valve.
The method according to any one of claims 6 to 12, wherein the diffusion bonding is such that the bonding surface between the first metal and the second metal is energized and diffusion bonding is performed in a liquid phase by heat generation of resistance thereof. How to make an engine valve.