WO2023286227A1

WO2023286227A1 - Method for manufacturing hollow engine valve

Info

Publication number: WO2023286227A1
Application number: PCT/JP2021/026549
Authority: WO
Inventors: 晃二久島; 徹弥小関; 大雅佐々木
Original assignee: フジオーゼックス株式会社
Priority date: 2021-07-15
Filing date: 2021-07-15
Publication date: 2023-01-19
Also published as: JPWO2023286227A1

Abstract

The present invention provides a method that is for manufacturing a hollow engine valve and that facilitates production management.　This method is for manufacturing a hollow engine valve 100 that has a shaft part 111, an umbrella-shaped part 112 disposed at the base end of the shaft part 111 and grows in diameter in an umbrella-like manner, and a hollow part 115 which is provided at least inside the shaft part 111, said method comprising: a heat-treatment step for bringing a solid round bar 10, which is a raw material made of a special steel, to a high-temperature state; a squeezing step for shaping an intermediate product 20 by reducing the diameter of a shank 21 of a workpiece, except for a one-end side thereof, that has been brought into a high-temperature state in the heat-treating step; an umbrella-shape formation step for increasing the diameter of the one-end side of the intermediate product 20 having a relatively increased diameter so as to form into an umbrella-like shape; a boring step for boring a bottomed hole 205 from the other-end side of an intermediate product 30, along the axis line thereof, that has undergone the shaping in the umbrella-shape formation step so as to form a semifinished product 200; and a cold forging step for cold-drawing the semifinished product 200. The squeezing step and the umbrella-shape formation step are performed simultaneously.

Description

Manufacturing method of hollow engine valve

The present invention relates to a method for manufacturing hollow engine valves.

Conventionally, engine valves, which allow intake gas to flow into the combustion chamber of engines such as automobiles and ships and discharge exhaust gas, have a hollow inside to contain a coolant such as metallic sodium to suppress temperature rise. There is a hollow engine valve (hereinafter also simply referred to as an engine valve) provided with a hollow portion (see Patent Document 1).

As shown in FIG. 10, there is a method of manufacturing such an engine valve in which a solid round bar 1 as a raw material is molded into an intermediate 2 or an intermediate 4 to form a semi-finished product 6. (Refer to Patent Document 2). The semi-finished product 6 has an umbrella-shaped portion 5 with an enlarged diameter on one end side and a cylindrical portion 8 extending in the axial direction and having a hollow hole 7 opened at the other end side. The intermediate body 2 is provided with the umbrella-shaped portion 5 by umbrella molding after the hollow hole 3 is provided by drilling, and the intermediate body 4 is provided with the umbrella-shaped portion 5 by umbrella molding first. , hollow holes 7 are provided by drilling.

JP 2017-190759 A Japanese Patent No. 4390291

However, in the case of such an engine valve manufacturing method, although there is a difference in the order of molding up to the semi-finished product 6 (the shape of the intermediate bodies 2 and 4), in either case, the conventional method is a solid circle. If the shaft diameters of the rod 1 and the semi-finished product 6 were not approximately the same, machining could not be performed. Therefore, it was necessary to set the shaft diameter of the solid round bar 1 to be the same as that of the semi-finished product 6 (for example, φa) in advance. . Therefore, when there are a plurality of engine valves with different shaft diameter specifications in the production plan, it is necessary to prepare solid round bars 1 according to the number of specifications, which complicates production management.

The present invention has been made in view of the above problems, and its object is to provide a method for manufacturing hollow engine valves that facilitates production management.

(1) A first aspect of the present invention is a hollow engine comprising a shaft portion, an umbrella portion expanding in diameter like an umbrella at a proximal end of the shaft portion, and a hollow portion provided at least inside the shaft portion. A method for manufacturing a valve, comprising: a heat treatment step in which a solid round bar made of special steel is heated to a temperature higher than a recrystallization temperature; An extruding step of forming an intermediate body by reducing the diameter of the trunk portion excluding it, a umbrella forming step of expanding the diameter of the relatively expanded one end side of the intermediate body into an umbrella shape, and the umbrella forming step. A drilling step of drilling a bottomed hole along the axis from the other end side of the intermediate body to form a semi-finished product, and a cold forging step of cold-squeezing the semi-finished product. and performing the squeezing process and the umbrella forming process at the same time.

According to the configuration (1) above, it is possible to form an intermediate body having a trunk portion with a different outer diameter from a solid round bar in the squeezing process. As a result, even when molding multiple types of valves, the outer diameter of the intermediate body can be adjusted accordingly, so the outer diameter of the solid round bar prepared in advance can be unified. Therefore, the production control cost can be reduced, and the degree of freedom in designing the hollow engine valve can be increased without being restricted by the outer diameter of the solid round bar.

In addition, by simultaneously carrying out the squeezing process and the umbrella forming process while maintaining the workpiece at a high temperature, the structures (crystal grains) of the body and umbrella of the intermediate and semi-finished product are controlled to be small. can do. As a result, the cold workability in the cold forging process is improved, the surface of the workpiece after the cold forging process becomes smooth, and the quality can be improved.

According to the present invention, it is possible to provide a method for manufacturing a hollow engine valve that facilitates production management.

It is a longitudinal section of a hollow engine valve in this embodiment. It is a schematic diagram similarly showing the molding process up to the valve head portion of the hollow engine valve. Similarly, it is a front partial vertical cross-sectional view of the one-shot forging device. Similarly, it is a front partial vertical cross-sectional view of the necking device. Similarly, it is a front partial vertical cross-sectional view of the necking device. Similarly, it is a front partial vertical cross-sectional view of the necking device. Similarly, it is a block diagram of the necking device. It is a figure showing the dimension etc. of the die|dye which concerns on a 1st drawing pattern, and the valve head part after molding. It is a figure showing the dimension etc. of the die|dye which concerns on a 2nd drawing pattern, and the valve head part after molding. FIG. 3 is a schematic diagram showing a molding process up to a semi-finished product of a conventional hollow engine valve.

Hereinafter, the present invention will be described in detail through one embodiment of the invention with reference to FIGS. 1 to 9, but the following embodiments are examples and do not limit the invention according to the claims.

Regarding the directions of the hollow engine valve 100, the

intermediate bodies

20 and 30 in the molding stage thereof, the semi-finished product 200, and the valve head portion 110 of the present embodiment, the tip end side of the shaft portion 111 (shaft end member 120 side) is upward. , the base end side of the shaft portion 111 (head portion 112 side) will be described below.

(Hollow engine valve 100)
A hollow engine valve (hereinafter simply referred to as an engine valve) 100 is a valve body provided in a cylinder head of an engine (not shown) of an automobile or the like and arranged inside an intake port and an exhaust port communicating with a combustion chamber. When the engine is actually running, it moves vertically to open and close the intake port and the exhaust port. The engine valve 100 enables intake gas to be supplied from the intake port into the combustion chamber by opening the intake port, and enables exhaust gas in the combustion chamber to be discharged from the exhaust port to the outside of the combustion chamber by opening the exhaust port.

As shown in FIG. 1, the engine valve 100 includes a valve head portion 110 that is a body portion and a shaft end member 120 that is a lid portion.

The valve head portion 110 includes a round bar-shaped shaft portion 111 and a head portion 112 that is continuously provided at the lower end portion of the shaft portion 111 and expands concentrically downward in an umbrella shape.

Inside the valve head portion 110, a hollow portion 115 with an upper opening is provided from the shaft portion 111 to the head portion 112. The hollow portion 115 has a bottom, the hollow portion 115 of the shaft portion 111 has a constant inner diameter, and the hollow portion 115 of the head portion 112 expands downward (bottom portion).

The valve head portion 110 includes a getter material such as titanium in the hollow portion 115 and a coolant such as metallic sodium (illustrated) that suppresses the temperature rise in the hollow portion 115 in a coolant enclosing process performed after molding the valve head portion 110 . ) is inserted, the shaft end member 120 is joined (for example, by friction welding) to the upper end portion of the shaft portion 111 to close the opening of the shaft portion 111 . As a result, the hollow portion 115 is sealed, and the coolant and the like are enclosed in the hollow portion 115 . As a result, the shaft end member 120 is integrated (unseparable) with the shaft portion 111 to form the shaft portion 111, and the engine valve 100 is completed.

If necessary, all or part of the engine valve 100 (part or all of the head portion 112, all or part of the shaft portion 111) may be heat-insulated with a metal having low thermal conductivity such as ceramic. may be applied, or surface treatment such as nitriding or polishing may be applied.

Here, the solid round bar 10, the first intermediate body 20, the second intermediate body 30, the semi-finished product 200, and the valve head portion 110, which are the states before machining of the engine valve 100 (hereinafter, these are simply referred to as workpieces). ) will be explained.

The solid round bar 10 shown in FIG. 2(a) is a cylindrical material made of special steel and has a constant outer diameter (φA). In this embodiment, even when a plurality of engine valves 100 (valve head portions 110) having shaft portions 111 with different outer diameters are formed, one type of solid body having a uniform outer diameter is used as described later. A round bar 10 should be prepared.

The first intermediate body 20 shown in FIG. 2(b) includes a body portion 21 having an outer diameter (φB) smaller than the outer diameter (φA) of the solid round bar 10, and an outer diameter (φA) of the solid round bar 10 at the base end. A head portion 22 having an outer diameter equal to or slightly larger than the diameter is provided.

The second intermediate body 30 shown in FIG. 2(c) includes a body portion 31 having an outer diameter (φC) slightly larger than the outer diameter (φB) of the body portion 21 of the first intermediate body 20, and and an umbrella-like portion 32 concentrically expanding in diameter toward the end.

A semi-finished product 200 shown in FIG. 2D includes a cylindrical portion 201 having a bottomed cylindrical hole 205 with an open tip, and an umbrella-like portion 32 of the second intermediate body 30 having the same shape as the umbrella-like portion 32 of the second intermediate body 30 at the base end. A section 202 is provided. Note that the outer diameter of the tubular portion 201 in the semi-finished product 200 and the outer diameter of the trunk portion 31 in the second intermediate 30 are equal (φC).

The valve head portion 110 shown in FIG. 2E includes a shaft portion 111 having an outer diameter (φD) smaller than the outer diameter (φC) of a cylindrical portion 201 of the semi-finished product 200 and a head portion 202 at the base end. and a hollow portion 115 formed from the shaft portion 111 to the umbrella portion 112 and having an inner diameter smaller than the inner diameter of the cylindrical hole 205 in the semi-finished product 200 .

In this embodiment, the valve head portion 110 is formed from the solid round bar 10 by means of a forging device 300 shown in FIG. 3, a boring device (not shown), and a necking device 400 shown in FIGS.

(Immediate forging device 300)
As shown in FIG. 3, the forging apparatus 300 heats the solid round bar 10 heat-treated to the recrystallization temperature or higher to form the second intermediate 30 by subjecting the solid round bar 10 to extrusion processing and umbrella forming, which will be described later. Forging is performed.

Specifically, the one-shot forging apparatus 300 includes, as an upper die, a punch holder 311 fixed to a slide (not shown) that reciprocates vertically by a mechanical press or the like, and a punch holder 311 that protrudes downward from the lower surface of the punch holder 311. It has a first punch 312 used in the squeezing process described later and a second punch 313 used in umbrella forming described later.

In addition, the one-shot forging device 300 includes, as lower molds, a pressing die 322 provided with a first forming hole 321 used in the pressing process described later, and a second forming hole used in umbrella forming described later. 323 is provided, and a die holder 325 to which the expression die 322 and the umbrella die 324 are fixed.

The first punch 312 has an outer diameter slightly smaller than the inner diameter of the first forming hole 321 and has a long columnar shape to the extent that the solid round bar 10 can be pushed deep into the first forming hole 321 . The second punch 313 has an outer diameter that is at least larger than that of a later-described umbrella forming portion 323a of the second forming hole 323, and has a short columnar shape.

The first forming hole 321 includes a guide portion 321a that expands concentrically upward in diameter into a mortar shape, and an insertion portion 321b that is connected to the lower portion of the guide portion 321a and has an inner diameter larger than the outer diameter of the solid round bar 10. and a squeezed portion 321d having an inner diameter (φB) smaller than the outer diameter (φA) of the solid round bar 10, which is connected to the lower portion of the insertion portion 321b via a tapered portion 321c whose diameter decreases downward. .

The second forming hole 323 is connected to a canopy forming portion 323a that expands concentrically upward in a substantially saucer-like diameter, and to the lower portion of the cap forming portion 323a. and a barrel forming portion 323b with a large inner diameter (φC).

The single forging device 300 is a solid round bar transported into the first forming hole 321 of the squeezing die 322 by a work transport device (not shown) such as a known picking robot capable of picking and transporting the work. 10 and the first intermediate 20 conveyed into the second forming hole 323 of the canopy forming die 324 are simultaneously pressed from above by the first punch 312 and the second punch 313, and are used for squeezing. The first intermediate 20 and the second intermediate 30 are simultaneously molded in the die 322 and the umbrella-forming die 324, respectively. That is, the single-shot forging device 300 simultaneously performs squeezing and umbrella forming.

The first intermediate body 20 and the second intermediate body 30 molded in this manner are provided with a work discharging device (illustrated as a ) is discharged from the first and second forming

holes

321 and 323 . The work conveying device conveys the first preform 20 discharged from the first forming hole 321 to the second forming hole 323 of the umbrella forming die 324, and the second preform 30 discharged from the second forming hole 323. It is conveyed to a drilling device (not shown) for drilling in the next step.

The drilling device includes a jig (not shown) capable of fixing the second intermediate body 30, and a bottomed hole (cylindrical shape) extending along the axis from the tip of the trunk portion 31 of the second intermediate body 30 fixed by the jig. 201) and a drill (not shown) capable of drilling. The drilling device forms a semi-finished product 200 by drilling the second intermediate 30 with a drill, and the work conveying device is a necking device for cold forging the semi-finished product 200 in the next process. Transport to 400.

(Necking device 400)
The necking device 400 thins the shaft by drawing the semi-finished product 200 in a plurality of steps at room temperature, and performs cold forging to form the valve head portion 110 .

As shown in FIGS. 4 to 6 and the like, the necking device 400 performs nine drawing steps #1 to #9 on the semi-finished product 200 using three drawing devices (first drawing device 400A, second drawing device 400B, and third drawing device 400B). The 3-squeeze device 400C) enables three processes to be processed simultaneously. In addition, the necking device 400 is provided between each of the first to third drawing devices 400A to 400C, in other words, every three processes, in order to reduce the actual temperature of the work that has risen due to the drawing. A carrier device 460A and a second cooling carrier device 460B (cooling process) are provided.
For convenience of explanation below, the semi-finished product 200 will be explained as semi-finished products 210 to 280 according to the outer diameter of the tubular portion 201 which changes in the drawing process.

(First to Third Expansion Devices 400A to 400C)
As shown in FIGS. 4 and 7, the first drawing device 400A includes a first die unit 410A having a plurality of dies for drawing the semifinished product 200 in a plurality of stages, and a first die unit 410A. a first height adjusting device 420A capable of adjusting the height of the semifinished products 200 to 220 and pressing the semifinished products 200 to 220 into the first to third dies d1 to d3 to form the semifinished products 210 to 230. A pressing device 440A, a first conveying device 450A capable of conveying the semi-finished products 200 to 230, and a lubricating oil (illustrated ) to the die of the first die unit 410A.

As shown in FIGS. 5 and 7, the second drawing device 400B has a plurality of dies for drawing the semifinished product 230 conveyed from the first conveying device 450A in a plurality of stages. A unit 410B, a second height adjusting device 420B for adjusting the height of the second die unit 410B, and pressing the semi-finished products 230 to 250 into the fourth to sixth dies d4 to d6 to form a semi-finished product 240. 260, a second conveying device 450B capable of conveying semi-finished products 230 to 260, and connected to the second conveying device 450B to supply lubricating oil to the die of the second die unit 410B. and a second lubricating oil adding device 470B that can be added.

As shown in FIGS. 6 and 7, the third drawing device 400C has a plurality of dies for drawing the semi-finished product 260 conveyed from the second conveying device 450B in a plurality of stages. A unit 410C, a third height adjusting device 420C capable of adjusting the height of the third die unit 410C, and pressing the semifinished products 260 to 280 into the seventh to ninth dies d7 to d9 to produce semifinished products. 270, 280 and the valve head portion 110, a third conveying device 450C capable of conveying the semi-finished products 260 to 280 and the valve head portion 110, and the third conveying device 450C. , and a third lubricating oil adding device 470C capable of adding lubricating oil (not shown) to the die of the third die unit 410C for reducing friction between the work and the die during drawing.

(First to third die units 410A to 410C)
As shown in FIGS. 4 to 6, the first die unit 410A includes first to third dies d1 to d3 (hereinafter simply referred to as dies d1 to d3) and a die holder D1 that supports the dies d1 to d3. . The second die unit 410B includes fourth to sixth dies d4 to d6 (hereinafter simply referred to as dies d4 to d6) and a die holder D2 that supports the dies d4 to d6. The third die unit 410C includes seventh to ninth dies d7 to d9 (hereinafter simply referred to as dies d7 to d9) and a die holder D3 that supports the dies d7 to d9.

The first to ninth dies d1 to d9 have cylindrical hole-shaped forming holes h1 to h9 and enlarged diameter portions w1 to w9 connected to the upper portions of the forming holes h1 to h9 and expanding upward in a mortar shape. set each. As shown in the upper column of FIG. 8, the inner diameter φ is set in each of the forming holes h1 to h9 (hn) of the dies d1 to d9 (dn), and the enlarged diameter portions w1 to w9 (wn) are: (the angle of the slope (inclination) plane when the forming hole hn in the die dn shown in the upper column of FIG. 8 is used as the reference plane) and the depth Γ (the upper end of the die dn shown in the upper column of FIG. 8). from the part to the lower end where the gradient (inclination) of the enlarged diameter part wn disappears) is set.

Specifically, the die d1 has a forming hole h1 with an inner diameter φ1 and an enlarged diameter portion w1 with an inclination angle θ2 and a depth Γ3. The die d2 has a forming hole h2 with an inner diameter φ2 and an enlarged diameter portion w2 with an inclination angle θ2 and a depth Γ3. The die d3 has a forming hole h3 with an inner diameter φ3 and an enlarged diameter portion w3 with an inclination angle θ2 and a depth Γ3. The die d4 has a forming hole h4 with an inner diameter φ4 and an enlarged diameter portion w4 with an inclination angle θ3 and a depth Γ3. The die d5 has a forming hole h5 with an inner diameter φ5 and an enlarged diameter portion w5 with an inclination angle θ3 and a depth Γ3. The die d6 has a forming hole h6 with an inner diameter of φ6 and an enlarged diameter portion w6 with an inclination angle of θ4 and a depth of Γ3. The die d7 has a forming hole h7 with an inner diameter φ7 and an enlarged diameter portion w7 with an inclination angle θ4 and a depth Γ3. The die d8 has a forming hole h8 with an inner diameter of φ8 and an enlarged diameter portion w8 with an inclination angle of θ5 and a depth of Γ3. The die d9 has a forming hole h9 with an inner diameter φ9 and an enlarged diameter portion w9 with an inclination angle θ6 and a depth Γ3.

The relationship of the inner diameters φ of the molding holes h1 to h9 is φ1>φ2>φ3>φ4>φ5>φ6>φ7>φ8>φ9. That is, the diameters of the forming holes h1 to h9 of the dies d1 to d9 are reduced in later steps.

Also, the relationship of the gradient angles θ of the enlarged diameter portions w1 to w9 is θ2>θ3>θ4>θ5>θ6. That is, the enlarged diameter portions w1 to w9 of the dies d1 to d9 become steeper in later steps. Further, all of the enlarged diameter portions w1 to w9 have a depth of Γ3.

In this way, in the drawing process, by adjusting (changing) the inner diameter φ of the forming holes h1 to h9 of the dies d1 to d9, the gradient angle θ of the enlarged diameter portions w1 to w9, and the depth Γ, respectively, Thus, the desired shape of the valve head portion 110 can be formed.

(First to third height adjustment devices 420A to 420C)
As shown in FIGS. 4 to 7, the first to third height adjustment devices 420A to 420C include a support plate 421 that supports the first to third die units 410A to 410C from below, and the support plate 421 moves up and down. A driving means 422 comprising a hydraulic, pneumatic, electric cylinder, or the like is provided. The first to third height adjusting devices 420A to 420C are connected to the die-side control section 480, respectively, and the heights of the first to third die units 410A to 410C can be adjusted under the control of the die-side control section 480. ing. Therefore, the first height adjusting device 420A can adjust the height of the dies d1 to d3, and the second height adjusting device 420B can adjust the height of the dies d4 to d6. The third height adjusting device 420C can adjust the height of the dies d7 to d9. The heights of the dies d1 to d9 may be adjusted by attaching and detaching spacers such as plates without using the driving means 422. FIG.

(First to third pressing devices 440A to 440C)
As shown in FIGS. 4 to 6, the first to third pressing devices 440A to 440C include a slide (not shown) that reciprocates vertically by a mechanical press such as a crank mechanism, and a punch fixed to the slide. A holder 441 and a plurality of (for example, three) first to third press conveying units 442a to 442c are arranged on the bottom surface of the punch holder 441 along the arrangement of the dies d1 to d9. In the first to third pressing devices 440A to 440C, the first pressing and conveying portion 442a is arranged on the left side in FIGS. The portion 442c is also arranged on the right side.

For example, as shown in FIG. 4, the first to third pressure conveying units 442a to 442c are conveyed by first to third conveying devices 450A to 450C described later (only the first conveying device 450A is shown in FIG. 4). A hook-shaped claw portion 446 capable of locking and lifting the umbrella-shaped portion 202 of the upside-down workpiece as shown in FIG. is pushed into the molding holes h1 to h9 of the dies d1 to d9 by moving downward to press and mold.

The first to third pressure transfer units 442a to 442c of the first to third pressure devices 440A to 440C receive and receive a plurality of (for example, three) works from the first to third transfer devices 450A to 450C described later. The workpieces are respectively pushed into the forming holes h1 to h9 of the dies d1 to d9, pressed, lifted, and handed over to the first to third conveying devices 450A to 450C.

In this way, the first to third pressing devices 440A to 440C only perform vertical reciprocating motion while holding three workpieces respectively, (1) pushing the three workpieces into the molding holes h1 to h9, and ( 2) Pressing and molding, and (3) three molded workpieces can be pulled out from the molding holes h1 to h9. can increase

In this embodiment, the first to third pressing devices 440A to 440C are connected to the work-side control unit 490, and the pressing speed and pressure applied to the work by the first to third pressing and conveying units 442a to 442c are controlled by Each of the first to third pressing devices 440A to 440C can be adjusted.

(First to third conveying devices 450A to 450C)
As shown in FIGS. 4 to 6, the first to third conveying devices 450A to 450C have a claw portion 451 having a pair of claws capable of pinching the cylindrical portion 201 of the work as a mechanism for moving the work. , a base 453 having a claw driving means (not shown) for opening and closing the claw portion 451, and a power source such as a motor capable of moving the base 453 in the advancing direction (horizontal direction) and the vertical direction (vertical direction) of the process. A drive means 454 comprising a connected rack and pinion mechanism or the like is provided. In addition, the front surfaces of the bases 453 of the first to third conveying devices 450A to 450C are connected to first to third lubricating oil adding devices 470A to 470C, respectively, as part of a mechanism for adding lubricating oil. Also, a plurality of downward nozzles 474 capable of leading out lubricating oil downward are arranged at regular intervals (for example, between a pair of claws 451 except for the rightmost claw 451 in FIGS. 4 to 6). ).

In addition, the first to third conveying devices 450A to 450C cooperate with the first to third lubricating oil adding devices 470A to 470C capable of storing and discharging lubricating oil (not shown), respectively, and the first to third die units Lubricating oil can be added to each of the dies 410A to 410C.

The first to third lubricating oil adding devices 470A to 470C include a storage tank 471 that can temporarily store lubricating oil, a supply means 472 such as a compressor that can output the lubricating oil in the storage tank 471 to the outside, and a storage It has a pipe 473 that connects the tank 471 and a plurality of nozzles 474 arranged on the base 453 . Although not shown in the drawing, the pipe 473 is connected to all the nozzles 474, and is arranged in a state in which it is bent enough to allow horizontal movement of the first to third conveying devices 450A to 450C.

When the nozzles 474 of the first to third conveying devices 450A to 450C are located directly above the dies (forming holes of the dies d1 to d9), the first to third lubricating oil adding devices 470A to 470C When the lubricating oil can be added to h1 to h9, the supply means 472 is operated to add the lubricating oil from the nozzle 474 through the pipe 473 to each of the dies immediately below. As shown in FIG. 7, the lubricating oil supply device 470 is connected to a work-side control section 490, and the work-side control section 490 controls the addition.

Specifically, the first to third lubricating oil addition devices 470A to 470C control the operation timing and operation time of the supply means 472 by setting the timer 490a (see FIG. 7) provided in the work side control unit 490. By doing so, the timing of adding the lubricant to the forming holes h1 to h9 of the first to ninth dies d1 to d9 (for example, adding every N cycles (forging N times)) and the amount of lubricant to be added can be set to the first Each of the to third lubricating oil adding devices 470A to 470C can be adjusted.

In addition, the first to third lubricating oil adding devices 470A to 470C are incorporated in the bases 453 of the first to third conveying devices 450A to 450C, respectively, and integrated with the first to third conveying devices 450A to 450C. good too.

The first to third conveying devices 450A to 450C transport a plurality of workpieces that have been lifted after being molded by the first to third pressing conveying units 442a to 442c of the first to third pressing devices 440A to 440C. It is received and slid in the direction of the next process (right direction in FIGS. 4 to 6). Then, the first to third conveying devices 450A to 450C transfer the workpieces received from the first and second pressure conveying units 442a and 442b to the second and third

pressure conveying units

442b and 442c, respectively, and the third pressure conveying units The work received from the section 442c is delivered to the first cooling transfer device 460A, the second cooling transfer device 460B, or the next process (for example, coolant sealing process), which will be described later.

The first conveying device 450A receives the work conveyed from the previous drilling process and transfers it to the first pressing conveying section 442a of the first pressing device 440A. The second conveying device 450B receives the work conveyed from the first cooling conveying device 460A, which will be described later, and delivers it to the first pressing conveying section 442a of the second pressing device 440B. The third conveying device 450C receives a work conveyed from a second cooling conveying device 460B, which will be described later, and delivers the work to the first pressing conveying section 442a of the third pressing device 440C.

As described above, the first to third conveying devices 450A to 450C are capable of simultaneously conveying (receiving and handing over) four works.

(First and second

cooling transfer devices

460A and 460B)
As shown in FIGS. 4 to 6, the first and second

cooling transfer devices

460A and 460B include a claw portion 461 having the same shape as the claw portion 446 of the pressure conveying portion 442, and a claw portion 461 that can be opened and closed. A driving means 462 is provided which allows vertical and horizontal movement of the claw 461 itself.

The first cooling transfer device 460A lifts the semi-finished product 230 that has been transferred by the first transfer device 450A after the drawing process by the first drawing device 400A is completed. The product 230 is cooled, and after a certain period of time has passed, the semi-finished product 230 is transferred to the second expansion device 400B.

The second cooling and conveying device 460B lifts the semi-finished product 260 that has been conveyed by the second conveying device 450B after the drawing process by the second drawing device 400B is completed. The product 260 is cooled, and after a certain period of time has passed, the semi-finished product 260 is transferred to the third expansion device 400C.

As shown in FIG. 7, the first and second

cooling transfer devices

460A and 460B are connected to the work-side control unit 490, and their waiting times can be adjusted. A blower or the like may be used for rapid cooling.

(control units 480, 490)
As shown in FIG. 7, the necking device 400 includes a die-side control unit 480 that controls the operations of the first to third height adjustment devices 420A to 420C, and the first to third expansion devices 400A to 400C. Third pressing devices 440A to 440C, first to third conveying devices 450A to 450C, first and second cooling and conveying

devices

460A and 460B, and first to third lubricating oil adding devices 470A to 470C work for controlling the operation and a side control unit 490 .

(First drawing by first drawing device 400A)
In the first drawing performed by the first drawing device 400A shown in FIG. 4(I), the first conveying device 450A uses the semi-finished product 200 conveyed from the previous drilling process and the dies d1 and d2. The molded

semi-finished products

210 and 220 are delivered to the first to third pressing conveying parts 442a to 442c of the first pressing device 440A, respectively, and the semi-finished product 230 molded by the die d3 is shown in FIGS. 4 and 5 ( It is delivered to the first cooling transfer device 460A where cooling processing is performed in II). The first to third pressing and conveying portions 442a to 442c of the first pressing device 440A push the semi-finished products 200 to 220 received from the first conveying device 450A into the forming holes h1 to h3 of the dies d1 to d3, respectively, and press them. Then, semifinished products 210 to 230 are molded at once. After that, the first to third pressing conveying units 442a to 442c lift the molded semifinished products 210 to 230 and deliver them to the first conveying device 450A. By repeating this, the cylindrical portion 201 of the semi-finished product 200 conveyed from the previous drilling process can be thinned in three steps (φ1→φ2→φ3) to form the semi-finished product 230. can.

(Second drawing by second drawing device 400B)
In the second drawing performed by the second drawing device 400B shown in FIG. 5(III), the second conveying device 450B uses the semi-finished product 230 conveyed from the first cooling and conveying device 460A and the dies d4 and d5 to form the 5 and 6 (I ∨) to the second cooling transfer device 460B where the cooling process is performed. The first to third pressing and conveying units 442a to 442c of the second pressing device 440B push the semifinished products 230 to 250 received from the second conveying device 450B into the forming holes h4 to h6 of the dies d4 to d6, respectively, and press them. Then, semi-finished products 240 to 260 are molded at once. After that, the first to third pressing conveying units 442a to 442c lift the molded semifinished products 240 to 260 and deliver them to the second conveying device 450B. By repeating this, the cylindrical portion 201 of the semi-finished product 230 conveyed by the first cooling and conveying device 460A can be thinned in three steps (φ4→φ5→φ6) to form the semi-finished product 260. .

(Third drawing by third drawing device 400C)
In the third drawing process performed by the third drawing device 400C shown in FIG. 6(∨), the third conveying device 450C forms the semi-finished product 260 conveyed from the second cooling and conveying device 460B and the dies d7 and d8. The

semi-finished products

270 and 280 thus obtained are delivered to the first to third pressing and conveying portions 442a to 442c of the third pressing device 440C, respectively, and the valve head portion 110 formed by the die d9 is transferred to the next coolant sealing step. hand over. The first to third pressing and conveying units 442a to 442c of the third pressing device 440C push the semi-finished products 260 to 280 received from the third conveying device 450C into the forming holes h7 to h9 of the dies d7 to d9, respectively, and press them. Then, the

semifinished products

270 and 280 and the valve head portion 110 are molded at once. After that, the first to third pressing conveying units 442a to 442c lift the molded

semifinished products

270 and 280 and the valve head portion 110 and deliver them to the third conveying device 450C. By repeating this, the cylindrical portion 201 of the semi-finished product 270 conveyed by the second cooling and conveying device 460B can be thinned in three stages (φ7→φ8→φ9) to form the valve head portion 110. .

In this way, the drawing is performed separately by the first to third drawing devices 400A to 400C instead of by a single device. It is possible to adjust the height of the die and the height of each die unit, which reduces the excessive load on the device and improves the precision of the drawing process.

Specifically, the heights of the first to third die units 410A to 410C, that is, the heights of the dies d1 to d9 can be appropriately changed by the first to third height adjusters 420A to 420C. You can fine-tune the bottom dead center on the press side. As a result, it is possible to finely adjust the appropriate pushing amount of the workpiece in each of the dies d1 to d9 of each of the die units 410A to 410C for each of the die units 410A to 410C, thereby avoiding excessive loads on the dies d1 to d9. Therefore, it is possible to extend the service life of the die units 410A to 410C as a whole.

Further, by the first to third conveying devices 450A to 450C and the first to third lubricating oil adding devices 470A to 470C, each of the forming holes h1 to h9 of the dies d1 to d9 in each of the die units 410A to 410C is specifically can add lubricating oil at a set timing and in a set amount for each of the molding holes h1 to h3, the molding holes h4 to h6, and the molding holes h7 to h9. As a result, it is possible to appropriately suppress an increase in heat generated by friction during pressing of the workpiece in each of the die units 410A to 410C, so that cold forging can be performed stably.

In addition, the first and second cooling and conveying

devices

460A and 460B not only convey the work, but also allow the work to stand by for a certain period of time so that the drawing process can be performed while actively lowering the temperature. As a result, it is possible to reduce processing defects caused by temperature rise of the workpiece and to improve the life of the dies.

In addition, in this embodiment, the first to third pressing devices 440A to 440C (pressing and conveying unit 442) and the first to third conveying device 450A are arranged in line with the linear arrangement of the dies d1 to d9 of the die holders D1 to D3. 450C are arranged linearly, but when the dies d1 to d9 of the die holders D1 to D3 are arranged in an annular shape, these devices are arranged and moved in an annular shape along the dies d1 to d9. You may do so.

(Manufacturing method of valve head portion 110 in engine valve 100)
As shown in FIG. 2, the forming process of the valve head portion 110 includes a hot forging process of forming an intermediate body 30 from the solid round bar 10 that has been heat-treated to the recrystallization temperature or higher in the heat treatment process, and a hot forging process of forming the intermediate body 30 into a semi-finished product 200, and a cold forging step of forming the valve head portion 110 from the semi-finished product 200 that has been annealed (softened) and then returned to room temperature.

(Hot forging process)
The hot forging process consists of an extruding process and a canopy forming process, and the heat-treated solid round bar 10 is simultaneously extruded and canopy formed by the forging device 300 .
Specifically, as shown in FIG. The first intermediate 20 conveyed to 323 is simultaneously pressed by the first punch 312 and the second punch 313 to form the first intermediate 20 in the first forming hole 321, and the second forming Umbrella forming for forming the second intermediate 30 in the hole 323 is performed at the same time. In this manner, the pressing process of FIGS. 2(a)-(b) and the umbrella-forming process of FIGS. 2(b)-(c) are performed simultaneously.

Here, in the method for manufacturing the engine valve 100, it is necessary to change the outer diameter of the cylindrical portion 201 of the semifinished product 200 before cold forging according to the shaft diameter of the shaft portion 111 of the engine valve 100. . Therefore, in the conventional engine valve manufacturing method, as shown in FIG. I needed it. However, in this embodiment, as shown in FIG. 2, even if the outer diameter (φA) of the solid round bar 10 is not the same as the outer diameter (φC) of the cylindrical portion 201 of the semi-finished product 200 (φA> φC), the outer diameter (φC) of the body portion 21 in the second intermediate 30 can be made the same as the outer diameter (φC) of the tubular portion 201 in the semi-finished product 200 by the squeezing step. That is, one type of solid round bar 10 (for example, the outer diameter is φA) is prepared, and the squeezing die 322 is appropriately changed to match the solid round bar 10 to the specifications of the engine valve 100 (finished product). The intermediate body 30 having the body portion 31 according to the request can be formed only by performing the squeezing process. As a result, there is no need to prepare various solid round bars 10 with different shaft diameters according to specifications, so production management can be facilitated and the outer diameter of the solid round bar 10 is limited. Therefore, the degree of freedom in designing the valve head portion 110 (engine valve 100) can be increased.

In addition, in this embodiment, by performing the squeezing process and the umbrella forming process at the same time, the lead time is not extended compared to the conventional engine valve manufacturing method that does not have the squeezing process.

In addition, by performing the squeezing process and the head forming process in a short time while maintaining the work in a high temperature state, the structure (crystal grains) can be managed to be small. This improves the cold workability in the cold forging process, smoothes the surface of the valve head portion 110 formed by cold forging, and improves the quality.

(Drilling process)
In the drilling process shown in FIGS. 2(c) to (d), a cylindrical portion 201 is provided by drilling a cylindrical hole 205 in the axial direction from the tip of the second intermediate 30 using a drill of a drilling device. to form a semi-finished product 200. After the drilling process, the semi-finished product 200 is annealed (softened).

(Cold forging process)
Drawing is performed in the cold forging process shown in FIGS. , the valve head portion 110 is formed. In the present embodiment, for example, nine drawing processes are divided into three drawing devices 400A to 400C, and the valve head portion 110 is formed from the semi-finished product 200 by simultaneously performing three drawing processes on three works. do.

Specifically, in the cold forging process, the first drawing device 400A reduces the outer diameter of the cylindrical portion 201 of the workpiece from φ1 to φ3 in three steps in the first drawing step, and the first cooling transfer device 460A The work is cooled in the first cooling step, the second drawing device 400B reduces the outer diameter of the cylindrical portion 201 of the work from φ4 to φ6 in three stages in the second drawing step, and the second cooling transfer device 460B The work is cooled in the second cooling process, and the third throttling device 400C reduces the outer diameter of the cylindrical portion 201 of the work from φ7 to φ9 in three steps in the third throttling step, thereby reducing the valve head portion 110. to mold.

In this way, by dividing the drawing process for each device by the first to third drawing devices 400A to 400C, the height adjustment of the first to third die units 410A to 410C, the adjustment related to the introduction of lubricating oil, or In addition to being able to adjust the pressure applied to the workpiece and the pushing speed, a cooling process can be added between the drawing processes, and the temperature of the workpiece can be actively lowered while drawing. It is possible to reduce defects in processing due to temperature rise and to improve the life of dies.

(drawing)
Drawing patterns (first drawing pattern and second drawing pattern) in the cold forging of this embodiment will be described with reference to FIGS. In this embodiment, medium carbon steel (for example, the carbon content is 0.48 to 0.58%), which is difficult to narrow down, is used as the work to be narrowed down by the first drawing pattern, and the work to be narrowed down by the second drawing pattern is adopts low-carbon steel (for example, carbon content of 0.25 to 0.35) that is easier to draw than the first drawing pattern.

(First aperture pattern)
As shown in the table in the middle column of FIG. 8 , in the first drawing pattern, drawing is performed in drawing steps #1 to #9 using dies d1 to d9 of die units 410A to 410C, and a semifinished product 200 is obtained. The valve head portion 110 is molded.

Specifically, in the first drawing pattern, in the drawing step #1, the semi-finished product 200 is drawn by a die d1 having a forming hole h1 with an inner diameter φ1 and an enlarged diameter portion w1 with an inclination angle θ2 and a depth Γ3. The processing forms a semi-finished product 210 .

Next, in the drawing step #2, the semi-finished product 210 is drawn by a die d2 having a forming hole h2 with a diameter of φ2 smaller than the inner diameter φ1 and an enlarged diameter portion w2 with an inclination angle θ2 and a depth Γ3. 220 is molded.

Next, in the drawing process #3, the semi-finished product 220 is drawn by a die d3 having a forming hole h3 of φ3 smaller than the inner diameter φ2 and an enlarged diameter portion w3 of a slope angle θ2 and a depth Γ3. 230 is molded.

Next, in the drawing process #4, the semi-finished product 230 is drawn by a die d4 having a forming hole h4 with a diameter of φ4 smaller than the inner diameter φ3, and an enlarged diameter portion w4 with a steeper slope θ3 than the inclination angle θ2 and a depth Γ3. A semi-finished product 240 is formed by drawing.

Next, in the drawing process #5, the semi-finished product 240 is drawn by a die d5 having a forming hole h5 with a diameter of φ5 smaller than the inner diameter φ4 and an enlarged diameter portion w5 with an inclination angle of θ3 and a depth of Γ3. Mold 250.

Next, in the drawing step #6, the semi-finished product 250 is drawn by a die d6 having a forming hole h6 with a diameter of φ6 smaller than the inner diameter φ5 and an enlarged diameter portion w6 with a steeper slope θ4 than the slope angle θ3 and a depth Γ3. A semi-finished product 260 is formed by drawing.

Next, in the drawing step #7, the semi-finished product 260 is drawn by a die d7 having a forming hole h7 with a diameter of φ7 smaller than the inner diameter φ6 and an enlarged diameter portion w7 with an inclination angle of θ4 and a depth of Γ3. 270 is molded.

Next, in the drawing step #8, the semi-finished product 270 is drawn by a die d8 having a forming hole h8 with a diameter of φ8 smaller than the inner diameter φ7 and an enlarged diameter portion w8 with a steeper slope θ5 than the slope angle θ4 and a depth Γ3. A semi-finished product 280 is formed by drawing.

In the final drawing process #9, the semifinished product 280 has a forming hole h9 with a diameter of φ9 smaller than the inner diameter φ8, and a die d9 having an enlarged diameter portion w9 with a steeper slope θ6 than the slope angle θ5 and a depth Γ3. The valve head portion 110 is formed by drawing with.

In the first drawing pattern, for example, the inner diameter φ of the molding holes h1 to h9, the gradient angle θ of the enlarged diameter portions w1 to w9, and the depth Γ are set in the range of 5 mm to 20 mm, and θ6 to θ2. is set in the range of 10° to 3°, and Γ3 is set in the range of 10 mm to 15 mm. As a result, in the valve head portion 110 formed according to the first throttle pattern, as shown in the lower column of FIG. Become.

(Second aperture pattern)
The second aperture pattern will be described with reference to FIG.
In the second drawing pattern, dies d41 to d46 are provided in die units 410A to 410C, drawing steps #1 to #6 are performed using dies d41 to d46, and semifinished product 200 is formed into valve head portion 110.

As shown in the middle column of FIG. 9, each of the dies d41 to d46 is connected to the upper portions of the cylindrical forming holes h41 to h46 and the forming holes h41 to h45 and expands upward in a mortar shape. Sections w41 to w46 are provided respectively. As shown in the upper column of FIG. 9, the inner diameter φ is set in each of the forming holes h41 to h46 (hn) of the dies d41 to d46 (dn), and each of the enlarged diameter portions w41 to w46 (wn) has a gradient An angle θ and a depth Γ are set.

Specifically, in the second drawing pattern, in the drawing step #1, the semi-finished product 200 is drawn by a die d41 having a forming hole h41 with an inner diameter of φ12 and an enlarged diameter portion w41 with an inclination angle of θ14 and a depth of Γ13. The processing forms a semi-finished product 210 .

Next, in the drawing process #2, the semi-finished product 210 is drawn by a die d42 having a forming hole h42 of φ14 smaller than the inner diameter φ12, and an enlarged diameter portion w42 having an inclination angle θ14 and a depth Γ13. 220 is molded.

Next, in the drawing process #3, the semi-finished product 220 is drawn by a die d43 having a forming hole h43 with a diameter of φ16 smaller than the inner diameter φ14, and an enlarged diameter portion w43 with a steeper slope θ15 than the inclination angle θ14 and a depth Γ13. A semi-finished product 230 is formed by drawing.

Next, in the drawing step #4, the semi-finished product 230 is drawn by a die d44 having a forming hole h44 with a diameter of φ19 smaller than the inner diameter φ16 and an enlarged diameter portion w44 with an inclination angle θ15 and a depth Γ13. Mold 250.

Next, in the drawing step #5, the semi-finished product 250 is processed by a die d45 having a forming hole h45 with a diameter of φ21 smaller than the inner diameter φ19, and an enlarged diameter portion w45 with a steeper slope θ16 than the slope angle θ15 and a depth Γ13. A semi-finished product 270 is formed by drawing.

Next, in the drawing step #6, the semi-finished product 270 is drawn by a die d46 having a forming hole h46 of φ24 smaller than the inner diameter φ21, and an enlarged diameter portion w46 having an inclination angle θ16 and a depth Γ13. 110 is molded. That is, in the second drawing pattern, the valve head portion 110 is formed in six steps of drawing.

The relationship of the inner diameters φ of the molding holes h41 to h46 is φ12>φ14>φ16>φ19>φ21>φ24.

Therefore, in the second drawing pattern, in the final drawing process #6, the drawing size range (φ21 →φ24) Drawing is performed.

Also, the relationship of the gradient angles θ of the enlarged diameter portions w41 to w46 of the second diaphragm pattern is θ14>θ15>θ16.

Further, all of the enlarged diameter portions w41 to w46 of the dies d41 to d46 have a depth of Γ13.

In the second drawing pattern, for example, φ24, φ21, φ19, φ16, φ14, and φ12 are set in the range of 6 mm to 15 mm for the inner diameter φ of the forming hole hn, the gradient angle θ, and the depth Γ of the expanded diameter portion wn. , .theta.16 to .theta.14 are set in the range of 8.degree. to 10.degree. for the gradient angle .theta. As shown in the lower column of FIG. 9, the valve head portion 110 thus formed has an outer diameter of φ6 mm at the shaft portion 111 and an inner diameter of φ3 mm at the upper hollow portion 115a of the hollow portion 115 .

That is, the valve head portion 110 formed by the second throttle pattern has substantially the same shape as the valve head portion 110 formed by the first throttle pattern, but the first throttle portion 110 is formed in nine steps. The valve head portion 110 is formed in six steps, which are fewer than the pattern. In addition, in the second drawing pattern, by adjusting the die in each drawing process as described above, buckling and cracking due to unreasonableness in drawing each time do not occur, and the drawing process itself is smooth. proceed to

As described above, in the drawing process, by adjusting (changing) the values of the inner diameter φ of the forming hole hn of the die dn, the gradient angle θ of the enlarged diameter portion wn, and the depth Γ, the desired form of the valve can be obtained. Not only can the umbrella portion 110 be formed, but the drawing process (cold forging process) can be shortened.

(Coolant sealing process, surface processing process)
In the coolant filling process, a getter material or a coolant such as metallic sodium is introduced into the hollow portion 115 of the valve head portion 110 formed by the cold forging process, and the shaft end member 120 is placed on the upper end portion of the shaft portion 111. By joining and fixing, the opening of the shaft portion 111 is closed, and the coolant and the like are enclosed in the hollow portion 115 .

Thus, the engine valve 100 is completed. In addition, in the surface processing step, if necessary, heat insulating coating may be applied with a metal having low thermal conductivity, or surface treatment such as nitriding or polishing may be applied.

Although the embodiments of the present invention have been described above, the following modifications can be adopted.

In this embodiment, nine drawing steps are used, three drawing devices (first to third drawing devices 400A to 400C) are provided, and three dies are installed in each drawing device. The drawing process is performed collectively, but it is not limited to this, and the drawing process may be, for example, 6 or more processes, the number of drawing devices is two or four or more, and the number of dies of the drawing device is two or more. It may be 4 or more.

D1 to D3 die unit dn die hn forming hole wn enlarged diameter portion 10 solid round bar 20 first intermediate body 21 body portion 22 head portion 30 second intermediate body 31 body portion 32 canopy portion 100 hollow engine valve 110 valve head portion 111 Shaft portion 112 Head portion 115 Hollow portion 120 Shaft end member 200 Semi-finished product 201 Cylindrical portion 202 Head-shaped portions 210 to 280 Semi-finished product 300 Single forging device 311 Punch holder 312 First punch 313 Second punch 321 First forming Hole 321a Guiding portion 321b Insertion portion 321c Tapered portion 321d Extracting portion 322 Extracting die 323 Second forming hole 323a Head forming portion 323b Body forming portion 324 Head forming die 325 Die holder 400 Necking device 400A First drawing device 400B Second Diaphragm device 400C Third diaphragm device 410A First die unit 410B Second die unit 410C Third die unit 420A First height adjustment device 420B Second height adjustment device 420C Third height adjustment device 421 Support plate 422 Driving means 440A First pressing device 440B Second pressing device 440C Third pressing device 441 Punch holder 442a First pressing conveying portion 442b Second pressing conveying portion 442c Third pressing conveying portion 446 Claw portion 447 Pressing portion 450A First conveying device 450B Second conveying Device 450C Third conveying device 451 Claw portion 453 Base 454 Driving means 460A First cooling and conveying device 460B Second cooling and conveying device 461 Claw portion 462 Driving means 470A First lubricating oil adding device 470B Second lubricating oil adding device 470C Third lubricating device Oil addition device 471 Storage tank 472 Supply means 473 Piping 474 Nozzle 480 Die side controller 490 Work side controller 490a Timer

Claims

A method for manufacturing a hollow engine valve comprising: a shaft portion; a head portion expanding in diameter like an umbrella at a proximal end of the shaft portion; and a hollow portion provided at least inside the shaft portion,
A heat treatment step in which a solid round bar, which is a material made of special steel, is brought to a high temperature state above the recrystallization temperature,
A squeezing step of forming an intermediate body by reducing the diameter of the body portion excluding one end side of the work that has been brought to a high temperature state in the heat treatment step;
an umbrella forming step of enlarging the diameter of the one end side of the intermediate body, which is relatively enlarged, into an umbrella shape;
A drilling step of drilling a bottomed hole along the axis from the other end of the intermediate body formed in the umbrella forming step to form a semi-finished product;
A cold forging step of cold-squeezing the semi-finished product,
A method for manufacturing a hollow engine valve, wherein the squeezing step and the umbrella forming step are performed simultaneously.