JP2014166644A - Method for manufacturing hollow engine valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a hollow engine valve, which can elongate the lifetime of a metal mold and enhance the yield by decreasing deformation resistance down to a surface pressure level where even a material with high deformation resistance at a high temperature can be economically used in a mass production.SOLUTION: A first intermediate member 20B including a diameter expansion tubular part 22 and a bottom plate part 21 is manufactured by using a first punch provided with a diameter shrinkage part, and a first die comprising a die hole provided with an enlarged diameter part to press-fit the first punch to a cylindrical billet material 20A arranged in the die hole of the first die, and by using a second cylindrical punch and a second die comprising a cylindrical die hole to arrange the first intermediate member in the die hole of the second die and press-fit the second punch to the first intermediate member 20B, so that the diameter expansion tubular part is shrunk to manufacture a second intermediate member 20C including a same-diameter tubular part 23 and the bottom plate part 21.

Description

  The present invention relates to a method for manufacturing a hollow engine valve in which a hole is formed from a shaft portion (body portion) to an enlarged diameter portion of a valve head portion.

  Various methods for producing hollow engine valves have been developed, and there are methods for forming hollow engine valves by forging. For example, Patent Document 1 discloses a method for manufacturing a valve head portion of a hollow engine valve and a hollow engine valve.

  In the method described in Patent Document 1, a cup-shaped intermediate member is manufactured by punching a cylindrical hole with a punch on the upper surface of a solid round bar (cylindrical billet material) by hot forging, and this lower part is forged. Expanding the diameter to produce the valve head part forming part, and the upper part of the valve head part forming part and the cylindrical part of the cup-shaped intermediate member are squeezed up by necking to provide the shaft part and the valve head part connected to the shaft part. A valve body with a hole formed over the upper part (expanded part) of the valve head part and welding a sealing member to the upper part of the shaft part of the valve body to obtain a finished product of the hollow engine valve Yes. In such a manufacturing method, as the billet material, a material having low deformation resistance at a high temperature such as structural steel (for example, SCM material), bolt steel, and some heat-resistant steel is used.

Japanese Patent No. 4390291 (for example, see paragraphs [0041] to [0043], [0047] to [0053], [FIG. 2], [FIG. 4], etc.)

In the manufacturing method of the valve head part of the hollow engine valve described above, if a material having high deformation resistance at high temperature such as nickel base (for example, NCF751) or austenitic heat resistant steel (for example, SUH35) is used as the billet material, The service life will be very short, leading to increased manufacturing costs. This is a condition in which the degree of processing exceeds 60% in the production of the above-described cup-shaped intermediate member, and the generated surface pressure exceeds 200 kgf / mm ² (2000 MPa). From high-speed steel, matrix high-speed steel, super steel, etc. This is because the surface pressure level (for example, about 150 kgf / mm ² ) that can be mass-produced economically is exceeded even if a general mold is used.

  Also, if the center position of the punch provided on the upper die and the die provided on the lower die are displaced, uneven thickness is generated in the cylindrical portion of the cup-shaped intermediate member according to this displacement, and even if this is necked The uneven thickness remains in the hollow shaft portion. Thereby, a yield will fall.

  From the above, the present invention has been made to solve the above-described problems, and even a material having a high deformation resistance at a high temperature is lowered to a surface pressure level that can be economically used in mass production. Thus, it is an object of the present invention to provide a method for manufacturing a hollow engine valve that can extend the life of a mold and increase the yield.

A method for manufacturing a hollow engine valve according to a first invention for solving the above-described problem is as follows.
A method of manufacturing a hollow engine valve having a hole formed from a shaft portion to a diameter-enlarged portion of a valve head portion,
A first punch provided with a reduced diameter portion that is reduced in diameter toward the distal end portion, and a die hole provided with a diameter-expanded portion that is opposed to the first punch and is increased in diameter toward the top. The diameter of the first die is increased by pressing the first punch into the cylindrical billet material disposed in the die hole of the first die. A first step of producing a first intermediate member comprising a cylindrical portion and a bottom plate portion connected to the lower portion of the enlarged cylindrical portion;
A second punch having a cylindrical shape and a second die that is opposed to the second punch and has a cylindrical die hole are provided in the first hole in the second die. By arranging a member and press-fitting the second punch into the first intermediate member, the diameter-expanded cylindrical portion is reduced in diameter, and has the same diameter from the proximal end to the distal end. It has the 2nd process of producing the 2nd intermediate member which consists of a cylinder part and a baseplate part connected to the lower part of the same diameter cylinder part.

A method for manufacturing a hollow engine valve according to a second invention for solving the above-described problem is as follows.
A method for manufacturing a hollow engine valve according to a first invention,
The first punch is characterized in that a tip portion thereof is a flat surface.

A method for manufacturing a hollow engine valve according to a third invention for solving the above-described problem is as follows.
A method for manufacturing a hollow engine valve according to a first invention,
It has a 3rd process which produces the valve head part formation part diameter-expanded rather than the said 2nd intermediate member by forging the lower part of the said baseplate part of the said 2nd intermediate member.

A method for manufacturing a hollow engine valve according to a fourth invention for solving the above-described problem is as follows.
A method for manufacturing a hollow engine valve according to a third invention,
A third die having a die hole formed in accordance with the same-diameter cylindrical portion of the second intermediate member is used, and the third die is used as the valve umbrella portion forming portion in the second intermediate member. And a valve head portion connected to the shaft portion by pressing the upper portion of the valve head portion and the same diameter cylindrical portion to squeeze the upper portion of the valve head portion forming portion and the same diameter cylindrical portion. The method further includes a fourth step of obtaining a valve main body having a hole formed from the shaft portion to an upper portion of the valve head portion.

  According to the method for manufacturing a hollow engine valve according to the present invention, the first punch provided with the reduced diameter portion that decreases in diameter toward the tip portion, and the die provided with the increased diameter portion that increases in diameter toward the upper portion. Using a first die having a hole, the first punch was press-fitted into a cylindrical billet material arranged in the die hole of the first die, thereby increasing the diameter from the proximal end toward the distal end. Pressure when processing a cylindrical billet material with a first punch by producing a first intermediate member composed of an enlarged cylindrical portion and a bottom plate portion connected to the lower portion of the enlarged cylindrical portion Can be dispersed in the radial direction of the first punch. Thus, the second intermediate member (cup-shaped intermediate member) is directly produced from the cylindrical billet material by the conventional cylindrical punch and the die provided with the cylindrical hole facing the punch. Compared to the case, the surface pressure level can be lowered. Furthermore, even if the surface pressure level is a material having a high deformation resistance at a high temperature, the surface pressure level can be lowered to such an extent that it can be economically mass produced. As a result, the life of the mold can be extended and the yield can be increased.

It is explanatory drawing of the manufacturing method of the hollow engine valve which concerns on one Embodiment of this invention, Comprising: The state before a process is shown to FIG. 1A, the state after a 1st process is shown to FIG. 1C, and 2nd is shown to FIG. 1C. FIG. 1D shows the state after the third processing, and FIG. 1E shows the state after the fourth processing. It is a figure for demonstrating the 1st process process in the manufacturing method of the hollow engine valve which concerns on one Embodiment of this invention, Comprising: The state before a 1st process is shown in FIG. 2A, FIG. FIG. 2C shows a state after the first processing process. It is a figure for demonstrating the 2nd process process in the manufacturing method of the hollow engine valve which concerns on one Embodiment of this invention, Comprising: The state before a 2nd process process is shown to FIG. 3A, and 2nd is shown to FIG. 3B. FIG. 3C shows a state after the second processing process.

  A method for manufacturing a hollow engine valve according to an embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, when producing a hollow engine valve from a cylindrical billet material, it is connected to the same-diameter cylindrical portion having the same diameter from the distal end to the proximal end and one end portion of the same-diameter cylindrical portion. A method for manufacturing a cup-shaped intermediate member (second intermediate member) composed of a bottom plate portion to be described will be described.

  As shown in FIG. 1A, a cylindrical billet material 20A having a diameter φ10 and a height h20 is prepared. Subsequently, as shown in FIG. 1B, a trumpet-shaped intermediate member (first intermediate member) 20 </ b> B having a height h <b> 21 is produced from the billet material 20 </ b> A by a first processing (hot forging) described later in detail. . The trumpet-shaped intermediate member 20 </ b> B includes a cylindrical bottom plate portion 21 and an enlarged diameter cylindrical portion 22. The enlarged cylindrical portion 22 has a height h22 and is connected to an edge portion on the upper surface of the bottom plate portion 21 and increases in diameter as it goes upward. The inner diameter of the lower end portion of the expanded cylindrical portion 22 is formed with a diameter φ11 (<φ10). At the upper end of the expanded cylindrical portion 22, the inner diameter is formed with a diameter φ15 (> φ10), and the outer diameter is formed with a diameter φ16 (> φ15).

  Subsequently, as shown in FIG. 1C, a cup-shaped intermediate member (second intermediate member) 20 </ b> C having a height h <b> 23 is formed from the trumpet-shaped intermediate member 20 </ b> B by a second processing process (cold forging) described later in detail. Make it. The cup-shaped intermediate member 20C includes a cylindrical bottom plate portion 21 and a cylindrical portion 23 having the same diameter and a height h24. In other words, the cup-shaped intermediate member 20C has a hole S21 having a depth h24. The same-diameter cylindrical portion 23 is connected to the edge portion on the upper surface of the bottom plate portion 21 and has the same diameter from the proximal end to the distal end. In the cylindrical portion 23 having the same diameter, the inner diameter is formed with a diameter φ11 and the outer diameter is formed with a diameter φ10.

  Subsequently, as shown in FIG. 1D, a semifinished valve body 10 of a hollow engine valve having a height h11 is produced from the cup-shaped intermediate member 20C by the third processing. The semifinished product 10 of the hollow engine valve has a shaft portion (body portion) 12 having a height h13, and a valve head portion forming portion 11 having a height h12 connected to the shaft portion (body portion) 12. A hole portion S11 having a diameter φ11 is formed from the shaft portion 12 to the enlarged diameter portion (upper portion) of the valve head portion forming portion 11. The depth of the hole S11 is h14 (> h13). In the third processing step, the bottom of the bottom plate portion 21 of the cup-shaped intermediate member 20C is forged as in a conventional hollow engine valve manufacturing method (see, for example, Patent Document 1). A semifinished product 10 of a hollow engine valve having a valve head portion 11 having a diameter larger than that of the intermediate member 20C is produced.

  Subsequently, as shown in FIG. 1E, a valve body 1 having a height h15 is produced from the semifinished product 10 of the hollow engine valve by the fourth processing. The valve body 1 has a shaft portion (body portion) 1b having a height h17 and a diameter φ14 (<φ11), and a valve head portion 1a having a height h16 connected thereto. A hole S1 is formed from the shaft portion 1b to the enlarged diameter portion (upper portion) of the valve head portion 1a. The depth of the hole S1 is h18 (> h17). The hole portion S1 is formed with a diameter φ13 (<φ11) in the shaft portion 1b, and is formed with φ11 in the enlarged diameter portion (upper portion) of the valve head portion 1a. In the fourth processing step, the size of the outer diameter of the same-diameter cylindrical portion 23 of the cup-shaped intermediate member 20C is the same as in the conventional method for manufacturing a hollow engine valve (see, for example, Patent Document 1). A third die having a die hole formed according to the above is used, and the third die is pressed against the upper portion of the valve head portion forming portion 11 and the shaft portion 12 of the valve body semifinished product 10 of the hollow engine valve. The upper part of the valve head part forming part 11 and the shaft part 12 in the semifinished product 10 of the hollow engine valve are provided with a shaft part 1b and a valve head part 1a connected to the lower part of the shaft part 1b. Then, the valve body 1 in which the hole S1 is formed from the shaft portion 1b to the upper portion of the valve head portion 1a is manufactured. A hollow engine valve (not shown) can be obtained by welding a sealing member (not shown) to the tip of the shaft 1b of the valve body 1.

  In the present embodiment, a trumpet-shaped intermediate member in which an enlarged cylindrical portion is formed on one end side by the first processing (hot forging) is produced, and then the second processing (cold forging). The cup-shaped intermediate member was obtained by reducing the diameter of the expanded cylindrical portion to the same cylindrical portion having the same diameter from the proximal end to the distal end.

  In the first processing step, a hot forging device shown in FIG. 2 is used. This forging device includes an upper die 31 and a lower die 41. The lower die 41 is provided with a first die 42. The lower die 41 and the first die 42 are provided with a hole 43 and a die hole 44, respectively. The die hole 44 includes a small diameter portion 44a, an enlarged diameter portion 44b, and a large diameter portion 44c. The small-diameter portion 44a is connected to the upper end portion of the hole portion 43, and is formed in a size that allows insertion of a billet material 20A and a lockout 45 described later. The enlarged diameter portion 44b is connected to the upper end portion of the small diameter portion 44a, and is formed with an enlarged diameter as it goes upward. The large diameter part 44c is connected to the upper end part of the enlarged diameter part 44b and is formed in a cylindrical shape. A lockout 45 is provided in the hole 43 and the die hole 44 so as to be movable back and forth (up and down).

The upper die 31 is provided with a first punch 32 facing a die hole 44 formed in the first die 42. The first punch 32 includes a base portion 32a, a large diameter portion 32b, a reduced diameter portion 32c, and a flat surface portion 32d. The large diameter portion 32 b is connected to a base portion 32 a provided so as to be connected to the upper mold 31. The reduced diameter portion 32c is connected to the lower end portion of the large diameter portion 32b and is formed with a reduced diameter as it goes downward. The reduced diameter portion 32c extends at a predetermined angle P with respect to the vertical direction. The inclination angle is in the range of 5 degrees to 30 degrees, and preferably in the range of 5 degrees to 20 degrees. When the inclination angle is smaller than 5 degrees or larger than 30 degrees, when a material having high deformation resistance at high temperature is used as the billet material, the surface pressure level is 150 kgf / mm when a trumpet-shaped intermediate member is produced. ^This is because it exceeds about ² . The flat surface portion 32d is formed to have the same size as the diameter φ11 of the hole S1 of the valve head portion 1a of the valve body 1. Thereby, in the 3rd or 4th processing after the 2nd processing, it is not necessary to perform processing for adjusting the hole of a hollow engine valve, and complication of manufacturing work can be controlled.

  In the second processing step, a cold forging device shown in FIG. 3 is used. This forging device includes an upper die 51 and a lower die 61. The lower die 61 is provided with a second die 62. The lower die 61 and the second die 62 are provided with a hole 63 and a die hole 64, respectively. The die hole 64 includes a small diameter part 64a and an enlarged diameter part 64b. The small-diameter portion 64a is connected to the upper end of the hole portion 63, has a cylindrical shape, and is formed in a size that allows a trumpet-shaped intermediate member 20B and a lockout 65 to be described later to be inserted therethrough. The enlarged diameter part 64b is connected to the upper end part of the small diameter part 64a, and is formed by expanding the diameter toward the upper side. A lockout 65 is provided in the hole 63 and the die hole 64 so as to be able to advance and retreat (vertically move).

  The upper die 51 is provided with a second punch 52 so as to face a die hole 64 formed in the second die 62. The second punch 52 is formed in a cylindrical shape. The punch 52 is formed in the same size as the diameter φ11 of the hole S1 of the valve head portion 1a of the valve body 1.

  Then, the manufacturing procedure of 20 C of cup-shaped intermediate members which are semi-finished products of a hollow engine valve is demonstrated using the hot forging apparatus and cold forging apparatus which were mentioned above.

  First, as shown in FIG. 2A, the billet material 20A is inserted into the small diameter portion 44a of the die hole 44 of the first die 42 of the hot forging device. At this time, the billet material 20A is arranged at a predetermined position by adjusting the position of the lockout 45. Subsequently, the upper die 31 and the first punch 32 are pressurized (press-fitted) in the direction of the arrow X1 toward the first die 42. Thereby, as shown to FIG. 2B, an enlarged diameter cylindrical part is formed in the upper part side. Then, when the wall thickness of the expanded cylindrical portion reaches a desired size, the upper die 31 and the first punch 32 are moved in the direction of the arrow X <b> 2 that is separated from the first die 42. Thereby, as shown in FIG. 2C and FIG. 1B, a trumpet-shaped intermediate member 20 </ b> B composed of a cylindrical bottom plate portion 21 and an enlarged diameter cylindrical portion 22 connected to the edge of the upper surface of the bottom plate portion 21 is obtained. It is done.

  Subsequently, as shown in FIG. 3A, the trumpet-shaped intermediate member 20B is inserted into the die hole 64 of the second die 62 of the cold forging device. The enlarged cylindrical portion 22 of the trumpet-shaped intermediate member 20 </ b> B is arranged along the enlarged diameter portion 64 b of the die hole 64. The lower end portion of the trumpet-shaped intermediate member 20B is supported by the lockout 65. Subsequently, the upper die 51 and the second punch 52 are pressurized (press-fitted) in the direction of the arrow X3 toward the second die 62. When the diameter-expanded cylindrical portion 22 is reduced in diameter and the same diameter cylindrical portion 23 having the same diameter is formed from the proximal end to the distal end, the upper die 51 and the second punch 52 are moved to the second die. It moves in the direction of an arrow X4 that is separated from 62. As a result, as shown in FIG. 3C and FIG. 1C, a cup-shaped intermediate member 20 </ b> C composed of the cylindrical bottom plate portion 21 and the same-diameter cylindrical portion 23 connected to the edge of the upper surface of the bottom plate portion 21 is obtained. It is done.

  Therefore, according to the method for manufacturing a hollow engine valve according to the present embodiment, the first punch 32 provided with the reduced diameter portion 32c that decreases in diameter toward the distal end portion, and the expanded diameter portion that increases in diameter toward the upper portion. The first punch 32 is press-fitted into the cylindrical billet material 20A disposed in the die hole 44 of the first die 42 using the first die 42 including the die hole 44 provided with 44b. Thus, a first intermediate member (trumpet-shaped intermediate member) 20B composed of an enlarged cylindrical portion 22 whose diameter is increased from the proximal end toward the distal end and a bottom plate portion 23 connected to the lower portion of the enlarged cylindrical portion 22 is provided. By manufacturing, the pressure when processing the cylindrical billet material 20 </ b> A with the first punch 23 can be dispersed in the radial direction of the first punch 32. Thus, the second intermediate member (cup-shaped intermediate member) is directly produced from the cylindrical billet material by the conventional cylindrical punch and the die provided with the cylindrical hole facing the punch. Compared to the case, the surface pressure level can be lowered. Furthermore, even if the surface pressure level is a material having a high deformation resistance at a high temperature, the surface pressure level can be lowered to such an extent that it can be economically mass produced. As a result, the life of the mold can be extended and the yield can be increased.

  Further, when the center axes of the upper mold 31 and the lower mold 32 are deviated from each other, the enlarged cylindrical portion 22 of the first intermediate member 20B produced in the first processing step is not unevenly distributed. The length is uneven in the circumferential direction. Even if it is such a shape, the length of a cylinder part can be equalized only by cut | disconnecting an edge part, and a yield can be improved.

  In the above description, the method for manufacturing the hollow engine valve for producing the first intermediate member 20B using the hot forging device in the first processing step has been described. However, the first processing step includes Thus, a hollow engine valve manufacturing method for producing the first intermediate member 20B using a cold forging device or a warm forging device may be used. Even such a method for manufacturing a hollow engine valve has the same effects as the above-described method for manufacturing a hollow engine valve.

  In the above, the manufacturing method of the hollow engine valve for producing the second intermediate member 20C using the cold forging device in the second processing step has been described. However, in the second processing step, It is also possible to use a method for manufacturing a hollow engine valve in which the second intermediate member 20C is manufactured using a warm forging device or a hot forging device. Even such a method for manufacturing a hollow engine valve has the same effects as the above-described method for manufacturing a hollow engine valve.

  According to the method for manufacturing a hollow engine valve according to the present invention, even if a material having a high deformation resistance at high temperature is used, it is possible to extend the life of the mold and increase the yield, which is beneficial in the automobile industry and the like. Can be used.

1 Valve Body 1a Valve Umbrella 1b Shaft (Body)
10 Semi-finished product of hollow engine valve body 11 Valve head forming part 12 Shaft (body)
20A Billet material 20B Trumpet-shaped intermediate member 20C Cup-shaped intermediate member 21 Columnar bottom plate portion 22 Expanded cylindrical portion 23 Same-diameter cylindrical portion 31 Upper mold 32 First punch 32a Base portion 32b Large diameter portion 32c Reduced diameter portion 32d Flat portion 41 Lower die 42 First die 43 Hole portion 44 Die hole 44a Small diameter portion 44b Large diameter portion 44c Large diameter portion 45 Lockout 51 Upper die 52 Second punch 61 Lower die 62 Second die 63 Hole portion 64 Die hole 64a Small diameter part 64b Large diameter part 65 Lockout

Claims (4)

A method of manufacturing a hollow engine valve having a hole formed from a shaft portion to a diameter-enlarged portion of a valve head portion,
A first punch provided with a reduced diameter portion that is reduced in diameter toward the distal end portion, and a die hole provided with a diameter-expanded portion that is opposed to the first punch and is increased in diameter toward the top. The diameter of the first die is increased by pressing the first punch into the cylindrical billet material disposed in the die hole of the first die. A first step of producing a first intermediate member comprising a cylindrical portion and a bottom plate portion connected to the lower portion of the enlarged cylindrical portion;
A second punch having a cylindrical shape and a second die that is opposed to the second punch and has a cylindrical die hole are provided in the first hole in the second die. By arranging a member and press-fitting the second punch into the first intermediate member, the diameter-expanded cylindrical portion is reduced in diameter, and has the same diameter from the proximal end to the distal end. A method for producing a hollow engine valve, comprising: a second step of producing a second intermediate member comprising a tubular portion and a bottom plate portion connected to a lower portion of the same-diameter tubular portion. A method for producing a hollow engine valve according to claim 1,
The method of manufacturing a hollow engine valve, wherein the first punch has a flat tip portion. A method for producing a hollow engine valve according to claim 1,
A hollow engine characterized by having a third step of forging a lower portion of the bottom plate portion of the second intermediate member to produce a valve head portion forming portion having a diameter larger than that of the second intermediate member. Manufacturing method of valve. A method for producing a hollow engine valve according to claim 3,
A third die having a die hole formed in accordance with the same-diameter cylindrical portion of the second intermediate member is used, and the third die is used as the valve umbrella portion forming portion in the second intermediate member. And a valve head portion connected to the shaft portion by pressing the upper portion of the valve head portion and the same diameter cylindrical portion to squeeze the upper portion of the valve head portion forming portion and the same diameter cylindrical portion. The method for manufacturing a hollow engine valve further includes a fourth step of obtaining a valve body in which a hole is formed from the shaft portion to an upper portion of the valve head portion.

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