JP2014140874A - Intermediate molding manufacturing metal mold, manufacturing method of intermediate molding, manufacturing method of engine valve, intermediate molding and engine valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermediate molding manufacturing metal mold, a manufacturing method of an intermediate molding, a manufacturing method of an engine valve, the intermediate molding and the engine valve, capable of restraining the occurrence of damage of a mandrel, when manufacturing the intermediate molding having an umbrella part, a cylinder part and a recessed part, when manufacturing a hollow engine valve.SOLUTION: An intermediate molding manufacturing metal mold is provided for molding the intermediate molding for forming an umbrella part, a cylindrical part corresponding to a stem part and a recessed part corresponding to a hollow part, in a manufacturing process of a hollow engine valve, and comprises: a first metal mold 10 for molding the umbrella part; a second metal mold 20 for molding an end surface of the umbrella part; and a mandrel 30 for molding the recessed part corresponding to the hollow part, and the second metal mold 20 forms a clearance recessed part 25 for forming a projection part of projecting from the end surface of the umbrella part in the intermediate molding in an area connectable to a first shape part 11.

Description

The present invention provides a mold for producing an intermediate molded product of a hollow engine valve, comprising a stem portion having a hollow portion formed therein and an umbrella portion formed at one end of the stem portion and expanding in diameter toward the one end side. The present invention relates to an intermediate molded product manufacturing method, an engine valve manufacturing method, an intermediate molded product, and an engine valve.

  As is well known, in an engine valve of an automobile or the like, metal sodium is provided by providing a hollow portion inside the engine valve in order to cope with higher performance of the engine and lower fuel consumption by reducing the weight and increasing heat transfer. It is done to enclose.

  An example of the manufacturing process of an engine valve having such a hollow part will be explained. First, a solid cylindrical material is forged, and the cylindrical part corresponding to the umbrella part and the stem part and the hollow part correspond to the cylindrical part. An intermediate molded product (first intermediate molded product) having a recess formed in this manner is molded.

  Next, the cylindrical portion is inserted into a cylindrical die having an inner diameter smaller than the outer diameter of the cylindrical portion of the intermediate molded product, and the drawing process is performed to reduce the dimensions of the cylindrical portion and the concave portion and extend the length. Then, the second intermediate molded product having a stem portion having an outer diameter, an inner diameter, and a length formed in predetermined dimensions is formed by sequentially performing a plurality of times.

  Then, in a dry inert gas atmosphere, metallic sodium Na cut into a predetermined dimension is put into the recess of the second intermediate molded product. Thus, after metal sodium Na of a predetermined dimension is put into the concave portion, the drawing process is subsequently performed a plurality of times in a dry inert gas atmosphere.

  After the metal sodium Na is introduced into the concave portion of the cylindrical portion, when the outer diameter and the inner diameter of the cylindrical portion are further reduced and the length is extended, the metallic sodium Na introduced into the concave portion is It is molded following the inner diameter of

And if the stem part whose outer diameter, inner diameter, and length are predetermined dimensions is shape | molded, in order to enclose metallic sodium Na, the opening part of a recessed part will be plastic-processed and obstruct | occluded and an engine valve (material) will be obtained. (For example, see Patent Document 1 below).
The metal Na may be added after the drawing process is completed.

  By the way, the molding of the first intermediate molded product includes, for example, a first mold in which a shape part for molding a stem part of an engine valve is formed, a second mold for molding an end face of an umbrella part of the engine valve, and a first mold. A mandrel that is inserted into a hole in which a cylindrical portion corresponding to the stem portion of the shape portion of the mold is formed and that forms a concave portion corresponding to the hollow portion in the cylindrical portion of the first intermediate molded product is provided. This is performed using a mold for manufacturing an intermediate molded product.

  When forming an intermediate molded product from a cylindrical material by a mold for manufacturing an intermediate molded product, the cylindrical material is placed on the end surface of the mandrel and the cylindrical material is loaded into the molding hole, and the second mold and the mandrel Is moved relative to (closes to) the cylindrical material to form an intermediate molded product.

JP2011-179326A

  However, when molding the first intermediate molded product, the second mold and the mandrel are brought relatively close to the cylindrical material loaded in the first mold, and the mandrel is pushed into the cylindrical material and charged. Therefore, a large load is applied to the mandrel, resulting in a problem that the life of the mandrel is short.

  Accordingly, the inventors have intensively studied the behavior of a mandrel when forming a cylindrical material into a first intermediate molded product by the above-described mold for manufacturing an intermediate molded product in a manufacturing process for manufacturing a hollow engine valve. The mandrel during molding is inserted from the end face of the cylindrical material, and the load increases as the shape part of the first mold is filled, and the molding of the umbrella part is completed by the first mold and the second mold. It was found that there was a high possibility that an impact load that suddenly increased instantaneously acted on the mandrel immediately before the start, and that this impact load had a great influence on the mandrel breakage. And the knowledge that a big effect can be acquired by the damage suppression of a mandrel by reducing this impact load was acquired.

  The present invention has been made in consideration of such circumstances, and a stem portion in which a hollow portion is formed inside, and an umbrella portion that is formed at one end of the stem portion and expands toward the one end side. In the manufacture of hollow engine valves equipped with a hollow cylinder, the cylindrical material is forged to suppress the occurrence of mandrel breakage, etc. in the intermediate molded product having the cylindrical part corresponding to the umbrella part and the stem part and the concave part corresponding to the hollow part. The present invention provides a mold for producing an intermediate molded product, a method for producing an intermediate molded product, a method for producing an engine valve, an intermediate molded product, and an engine valve that can be molded while improving the production efficiency of the engine valve. Objective.

In order to achieve the above object, the present invention proposes the following means.
The invention according to claim 1 manufactures a hollow engine valve including a stem portion having a hollow portion formed therein and an umbrella portion formed at one end of the stem portion and having a diameter increasing toward the one end side. In the engine valve manufacturing process, a cylindrical material heated to a predetermined temperature is forged to form an intermediate molded product in which the umbrella portion, the cylindrical portion corresponding to the stem portion, and the concave portion corresponding to the hollow portion are formed. A mold for producing an intermediate molded product, wherein a first mold in which a first shape part for molding the umbrella part and the cylindrical part is formed, a second mold for molding an end surface of the umbrella part, A mandrel that is inserted into the first shape portion of the first mold and forms a corresponding recess of the hollow portion formed in the cylindrical portion, and the second die is connected to the first shape portion. In the possible area, the end of the umbrella part in the intermediate molded product A recess missed forming a protrusion protruding is formed from characterized.

  The invention according to claim 3 manufactures a hollow engine valve comprising a stem portion having a hollow portion formed therein and an umbrella portion formed at one end of the stem portion and having a diameter increasing toward the one end side. In the process, a method for producing an intermediate molded product having a cylindrical portion corresponding to the stem portion, an umbrella portion, and a concave portion corresponding to the hollow portion, wherein the first shape portion for forming the umbrella portion and the cylindrical portion includes: The formed first mold, the second mold for molding the end face of the umbrella part, and the hollow part formed in the cylindrical part corresponding to the first shape part of the first mold are provided. A cylindrical material heated to a predetermined temperature is loaded into a mold for manufacturing an intermediate molded article including a mandrel for forming a recess, and the second mold and the mandrel are moved toward the cylindrical material. Move to the first mold and the second mold And forming the cylindrical portion corresponding to the umbrella portion and the stem portion, and inserting the mandrel into the cylindrical material to form the concave portion corresponding to the hollow portion. It forms while forming the convex part which protrudes in the said one end side from the end surface of the said umbrella part by the relief recessed part formed in the area | region connected with one shape part, It is characterized by the above-mentioned.

  Invention of Claim 5 is a manufacturing method of the engine valve using the intermediate molded product of Claim 3 or Claim 4, Comprising: The said intermediate molded product is shape | molded, The cylindrical part of the said intermediate molded product is formed. After sequentially drawing and forming the cylindrical portion to a size corresponding to the stem portion, metal sodium Na is introduced into the concave portion corresponding to the hollow portion, or the cylindrical portion of the intermediate molded product is drawn sequentially. Then, the cylindrical portion is molded to a size corresponding to the stem portion, and metal sodium Na is introduced into the concave portion corresponding to the hollow portion in the process of drawing, and the cylindrical portion corresponds to the stem portion. It shape | molds to a dimension and closes the opening part of the recessed part corresponding to the said hollow part, It is characterized by the above-mentioned.

  The invention described in claim 6 is an intermediate molded product, which is manufactured by the method for manufacturing an intermediate molded product according to claim 3 or 4.

  The invention according to claim 7 is an engine valve, which is manufactured by the method for manufacturing an engine valve according to claim 5.

According to the mold for manufacturing an intermediate molded product, the method for manufacturing the intermediate molded product, the method for manufacturing the engine valve, the intermediate molded product, and the engine valve according to the present invention, in the manufacture of the engine valve, the umbrella portion, When manufacturing an intermediate molded product having a cylindrical portion corresponding to the stem portion and a concave portion corresponding to the hollow portion, the load applied to the mandrel for forming the concave portion formed in the cylindrical portion is reduced, and the mandrel And the life of the mandrel is extended.
As a result, it is possible to improve the production efficiency when producing the intermediate molded product and the engine valve, thereby reducing the manufacturing cost.

  In this specification, the region connectable to the first shape portion in which the relief recess is formed refers to a recess or the like in which the material being molded into the intermediate molded product forms a burr directly or from the first shape portion (burr road) Etc.) is designated as an area that can be flowed in through.

  The invention according to claim 2 is the mold for manufacturing an intermediate molded product according to claim 1, wherein the relief recess is a radial direction of an outer peripheral edge of the umbrella portion of the intermediate molded product of the second mold. A mold for manufacturing an intermediate molded product, characterized in that it is formed on the outer periphery.

  Invention of Claim 4 is a manufacturing method of the intermediate molded product of Claim 3, Comprising: The convex part formed by the said escape recessed part is on the radial direction outer periphery of the outer periphery of the umbrella part of the said intermediate molded product It is formed.

  According to the mold for manufacturing an intermediate molded product and the method for manufacturing the intermediate molded product according to the present invention, when the intermediate molded product is manufactured in the manufacture of the engine valve, the convex portion is the diameter of the outer peripheral edge of the umbrella portion of the intermediate molded product. Since it is formed on the outer periphery in the direction, the load applied to the mandrel is reduced, and the mandrel is prevented from being broken, thereby extending the life of the mandrel.

  Further, by controlling the position where the convex portion is generated, it is possible to easily remove the convex portion generated by the relief concave portion when removing the burr, and to shorten the machining step in the subsequent process. . As a result, the production efficiency when manufacturing the intermediate molded product can be greatly improved.

  Here, the radial outer periphery of the outer peripheral edge of the umbrella part of the intermediate molded product is a position formed overlapping with the burr formed on the outer peripheral side of the umbrella part, and the burr formed on the outer peripheral side of the umbrella part. The s region located further outward in the radial direction.

According to the mold for manufacturing an intermediate molded product, the method for manufacturing the intermediate molded product, the method for manufacturing the engine valve, the intermediate molded product, and the engine valve according to the present invention, in the manufacture of the engine valve, the umbrella portion, When manufacturing an intermediate molded product having a cylindrical portion corresponding to the stem portion and a concave portion corresponding to the hollow portion, the load applied to the mandrel forming the concave portion formed in the cylindrical portion is reduced, and the mandrel is damaged. And the life of the mandrel can be extended.
As a result, it is possible to improve the production efficiency when producing the intermediate molded product and the engine valve, thereby reducing the manufacturing cost.

It is a figure explaining an example of the manufacturing process of the hollow engine valve which concerns on one Embodiment of this invention. It is a figure which shows the outline of the intermediate molded product in the hollow engine valve manufacturing process which concerns on one Embodiment of this invention. In the hollow engine valve manufacturing process which concerns on one Embodiment of this invention, it is a figure explaining schematic structure of the metal mold | die for intermediate molded product used for shape | molding an intermediate molded product. It is a figure explaining the process in which the intermediate molded product which concerns on one Embodiment of this invention is shape | molded with the metal mold | die for intermediate molded product manufacture, (A) is a cylindrical material with which the metal mold | die for intermediate molded product manufacture was loaded. It is a figure which shows a state, (B) is a figure which shows the state by which the intermediate molded product was shape | molded in the metal mold | die for intermediate molded product manufacture. It is a figure explaining the effect by the position of the escape recessed part in the metal mold | die for intermediate molded product manufacture which concerns on one Embodiment of this invention. It is a figure explaining the effect by the position of the escape recessed part in the metal mold | die for intermediate molded goods shown in FIG. 5, and is a graph evaluated by the load loaded on the mandrel. It is a figure explaining the effect of the escape recessed part in the metal mold | die for intermediate molded product manufacture which concerns on one Embodiment of this invention. It is a figure explaining the modification which concerns on the metal mold | die for intermediate molded product manufacture which concerns on one Embodiment of this invention. It is a figure explaining the modification of the manufacturing process of the hollow engine valve which concerns on one Embodiment of this invention.

Hereinafter, with reference to FIG. 1, an example of the manufacturing process of the hollow engine valve V according to an embodiment of the present invention will be described.
For example, as shown in FIG. 1 (S19), the hollow engine valve V includes a stem portion S2 having a hollow portion H2 formed therein, and an umbrella that is formed at one end of the stem portion S2 and expands toward the one end side. The metal part Na is enclosed with the hollow part H2.

1) First, a solid cylindrical material M (for example, a diameter of about 16 to 20 mm and a length of about 35 to 50 mm) is prepared (step S11).
2) Next, the cylindrical material M heated to a predetermined temperature is loaded into a mold for producing an intermediate molded product and forged. In forging with a mold for manufacturing an intermediate molded product, an intermediate molded product W is manufactured by forming a cylindrical portion S corresponding to an umbrella A, a stem portion S2 and a concave portion H corresponding to a hollow portion H2 from a cylindrical material M. (Step S12).

3) Next, the cylindrical portion S of the intermediate molded product W is inserted into a die D1 in which a hole having an inner diameter smaller than the outer diameter of the cylindrical portion S (for example, about −0.5 to −1.5 mm) is formed. Perform drawing. As a result, an intermediate molded product W1 in which the outer diameter of the cylindrical portion S and the inner diameter of the concave portion H are reduced and the length of the cylindrical portion S is extended is obtained (step S13).
Here, for convenience, an intermediate molded product formed by the intermediate molded product manufacturing die is indicated by a symbol W, and an intermediate molded product to be drawn is indicated by a symbol W1. Further, the cylindrical portion of the intermediate molded product W1 is denoted by reference numeral S1, and the concave portion is denoted by reference numeral H1.

4) Next, the cylindrical portion S1 of the intermediate molded product W1 formed in S13 is inserted into a die D2 in which a hole having an inner diameter smaller than that of the die D1 is formed to perform drawing.
As a result, an intermediate molded product W1 in which the outer diameter of the cylindrical portion S1 and the inner diameter of the concave portion H1 are further reduced and the length of the cylindrical portion S1 is extended is obtained (step S14).

5) Subsequently, the cylindrical portion S1 of the intermediate molded product W1 drawn in the previous process is inserted into the die Dx in which the hole having a smaller inner diameter is formed stepwise than the die used in the drawing process in the previous process. By drawing, the outer diameter of the cylindrical portion S1 and the inner diameter of the concave portion H1 are reduced, and the intermediate molded product W1 in which the length of the cylindrical portion S1 is extended is sequentially obtained (step S15).

6) Next, the cylindrical portion S1 of the intermediate molded product W1 is inserted into the die Dx + 1 in which a hole smaller than the die Dx is formed, and drawing is performed, and the outer diameter of the cylindrical portion S1 and the inner diameter of the recess H1 are reduced. In addition, the length of the cylindrical portion S1 is extended (step S16).

7) In the same manner, the drawing process is sequentially performed using a plurality of dies Dn in which the inner diameter is gradually reduced in steps, and the outer diameter of the cylindrical portion S1 and the inner diameter dimension of the concave portion H1 are set. The diameter of the cylindrical portion S1 is reduced stepwise and the length of the cylindrical portion S1 is extended stepwise to obtain an intermediate molded product W1 having a prescribed size corresponding to the stem portion (step S17).

8) When the cylindrical portion S1 corresponding to the stem portion S and the concave portion H1 corresponding to the hollow portion H2 are formed, the drawing process is finished, and the intermediate molded product W1 is placed in a dry inert gas atmosphere (for example, dry nitrogen gas). Then, block-shaped metallic sodium Na (for example, a hexahedron having a side of about 8 to 13 mm on each side) formed from raw material sodium to a predetermined size is introduced into the interior from the opening at the top of the recess H1 (step S18).
9) When the outer diameter of the cylindrical portion S1, the inner diameter of the concave portion H1, and the length of the cylindrical portion S1 are formed to the specified dimensions, the end portion of the cylindrical portion S1 that is opened is plastically closed using a mold Dm. (Step S19).
As a result, a hollow engine valve V in which metallic sodium Na is sealed in the hollow portion H2 of the stem portion S2 is obtained.

Next, an intermediate molded product W according to an embodiment of the present invention will be described with reference to FIG. FIG. 2 is a diagram illustrating an intermediate molded product W according to an embodiment.
The intermediate molded product W includes an umbrella part A and a cylindrical part S, and a concave part H is formed in the cylindrical part S.

The umbrella part A is formed on one end side of the cylindrical part S, and the diameter thereof is increased toward the one end side, and the end surface on one end side is formed in a substantially conical shape having a circular outer peripheral edge.
Moreover, the burr | flash B produced | generated when the intermediate molded product W is shape | molded is formed in the outer peripheral edge of the one end side at the radial direction outward of an outer peripheral edge. Further, the burr B is formed with a convex portion F that protrudes toward one end side.

  The cylindrical portion S corresponds to the stem portion S2 of the hollow engine valve V, is connected to the other end side of the umbrella portion A, and has a larger diameter than the stem portion S2.

  The concave portion H corresponds to the hollow portion H2 of the hollow engine valve V, is formed in the longitudinal direction of the cylindrical portion S, and extends from the cylindrical portion S to the umbrella portion A.

  Next, with reference to FIG. 3, a mold for producing an intermediate molded product for molding an intermediate molded product according to an embodiment will be described. FIG. 3 is a diagram illustrating a schematic configuration of a mold for manufacturing an intermediate molded product according to an embodiment.

  The mold 1 for manufacturing an intermediate molded product includes a lower mold (first mold) 10, an upper mold (second mold), and a mandrel 30.

  The lower mold 10 has, for example, an outer shape that is substantially cylindrical, and a first shape portion 11 having an umbrella portion forming portion 11A for forming the umbrella portion A and a cylindrical portion forming hole 11B for forming the cylindrical portion S. Is formed. Further, on one end side (upper mold 20 side) of the umbrella part molding part 11A, it extends radially outward from the outer peripheral edge of the umbrella part molding part 11A and is used for forming a circular burr as viewed from the direction of the axis O. A recess 12 is formed.

  The upper mold 20 is formed on the surface on the other end side (lower mold 10 side), and includes an end surface shape portion 21 including a shape portion corresponding to the end surface on the one end side of the umbrella portion A, and a relief recess 25. The umbrella part A is formed by pressing one end side of the cylindrical material M, and is configured in a substantially flat plate shape, for example.

  The relief recess 25 is formed in a region connectable to the first shape portion 11. In this embodiment, for example, above the burr forming recess 12, the width around the axis O is about 1 mm or more and the depth is about 0. The escape recess 25 is entirely formed in a region corresponding to the inside of the burr forming recess 12. That is, the burr B generated when the intermediate molded product W is molded is formed so as to overlap with the burr path through which the burr B passes.

The mandrel 30 is formed in, for example, a cylindrical shape, and is inserted into the cylindrical part forming hole 11B of the lower mold 10 to correspond to the hollow part H2 of the hollow engine valve V formed in the cylindrical part S. Is formed.
Further, the upper mold 20 and the mandrel 30 are configured so as to ensure a speed balance when forming the intermediate molded product W by operating in synchronization with a predetermined speed difference. .

  Next, with reference to FIG. 4, the shaping | molding of the intermediate molded product W by the metal mold | die 1 for intermediate molded product manufacture which concerns on one Embodiment is demonstrated. FIG. 4 is a view for explaining the process of forming the intermediate molded product W by the intermediate molded product manufacturing die 1 according to the embodiment. FIG. 4A shows the cylindrical material M in the intermediate molded product manufacturing die 1. Is a diagram showing a state in which is inserted, and (B) is a diagram showing the molding of the intermediate molded product W by the mold 1 for manufacturing an intermediate molded product.

1) First, as shown in FIG. 4A, a cylindrical material M heated to a predetermined temperature is loaded into a mold 1 for manufacturing an intermediate molded product. In this embodiment, the cylindrical material M is placed and loaded on the one end 31 of the mandrel 30 in the cylindrical part forming hole 11B in the lower mold 10, for example.
2) Next, as shown in FIG. 4B, the upper mold 20 is lowered toward the cylindrical material M, and the mandrel 30 is raised toward the upper mold 20. At this time, the upper mold 20 and the mandrel 30 approach each other and move relative to the lower mold 10.
At this time, when raising the cylindrical material M, the mandrel 30 is inserted into the cylindrical material M in the direction of the axis O after the upper end of the cylindrical material M comes into contact with the upper mold 20, and the concave portion Molding while extending H in the axial direction.
Further, in the process in which the cylindrical material M is formed by the upper mold 20 and the mandrel, the material flows toward the outer peripheral edge of the umbrella portion A as indicated by an arrow, and the burr forming recess 12 is formed from the outer peripheral edge of the umbrella portion A. As the material enters, the material flows into the escape recess 25.

According to the mold 1 for manufacturing an intermediate molded product, when the intermediate molded product W in which the umbrella portion A, the cylindrical portion S, and the concave portion H are formed from the cylindrical material M, the concave portion H formed in the cylindrical portion S is formed. The load applied to the mandrel 30 is reduced, so that the mandrel 30 is prevented from being damaged and the life of the mandrel 30 is extended.
As a result, it is possible to improve the production efficiency when producing the intermediate molded product and the engine valve, thereby reducing the manufacturing cost.

  Further, when removing the burrs B generated on the outer peripheral edge of the umbrella portion A of the intermediate molded product W, the convex portion F formed by the relief concave portion 25 can be easily removed. The production efficiency when molding W can be greatly improved.

Next, effects of the present invention will be described with reference to FIGS.
FIGS. 5 and 6 are views for explaining the effect of the position of the relief recess in the intermediate mold manufacturing die according to the embodiment. FIGS. 5A, 5B, and 5C are the relief recesses. FIG. 6 shows the effect of the mold for manufacturing an intermediate molded product provided with the relief recess shown in FIGS. 5 (A) and 5 (C) by the axial load applied to the mandrel. It is a graph to explain.

  In FIG. 6, reference numeral S indicates an axial load applied to the mandrel when no relief recess is formed in the second mold. Immediately before the molding is finished, The impact load is about 1.5 times that of the load.

  On the other hand, in FIG. 6, the reference numeral A indicates that the escape recess is formed on the axis of the mandrel near the center of the second mold as shown in FIG. This is the load applied to the mandrel. The axial load applied to the mandrel gradually increases at the timing when the impact load is generated in the molding with the intermediate molded product mold in which the relief recess is not formed, but the generation of the impact load is not recognized. The axial load at is reduced to about 50% compared to the case where there is no relief recess, and a sufficient effect is recognized.

Further, in FIG. 6, reference numeral B indicates that the burr road of the intermediate molded product is connected to the outer periphery from the first shape portion of the first mold of the second mold as shown in FIG. 5C. Is an axial load applied to the mandrel when it is connected to, and is larger than the symbol A shown in FIG.
However, the axial load applied to the mandrel gradually increases at the timing when the impact load is generated in the molding by the intermediate molded product manufacturing mold in which the relief recess is not formed, and the generation of the impact load is not recognized. The axial load is reduced to about 60%, and a sufficient effect is recognized.

Next, with reference to FIG. 7, the axial stress, load, and productivity depending on the position where the relief recess is formed in the intermediate molding die will be described.
FIG. 7 is a diagram showing evaluations regarding axial stress, load, and productivity when a relief recess is formed at the position shown in FIGS. 5 (A), (B), and (C).

The center (A) shown in FIG. 7 shows the evaluation when the escape recess is formed on the axis of the mandrel near the center of the second mold as shown in FIG. 5 (A). The axial stress and load applied to the mandrel is greatly reduced and good.
However, since the convex portion protrudes on the end face side of the umbrella portion of the intermediate molded product, post-processing for removing the convex portion is required in the subsequent process, and thus productivity is reduced.

Further, on the burr road (B) shown in FIG. 7, a relief recess is formed on the burr road on the outer circumference of the umbrella portion on the burr road of the second mold, as shown in FIG. 5 (B). The axial stress and load applied to the mandrel are reduced and good.
Furthermore, since the convex part protrudes from the burr generated on the outer peripheral edge of the umbrella part of the intermediate molded product, the convex part can be easily removed when removing the burr, and it is necessary to newly provide a post-treatment such as a chip. This improves productivity.

Further, the outer side (C) shown in FIG. 7 corresponds to the case where a relief recess is formed in the outer side region including the outer peripheral edge of the burr road of the second mold as shown in FIG. 5 (C). Although the evaluation is shown and the effect is smaller than when the relief recess is formed on the burr road, the axial stress and load applied to the mandrel are reduced and good.
Also in this case, since the protruding portion protrudes so as to be connected to the burr on the outer peripheral edge of the umbrella portion of the intermediate molded product, the protruding portion can be easily removed when removing the burr, and post-processing such as a chip Since it is not necessary to provide a new one, productivity is improved.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above embodiment, the case where the relief recess 25 is formed above the burr forming recess 12 has been described, but it may be formed closer to the center as shown in FIG. As shown in FIG. 5C, it may be formed on the outer side of the burr forming recess 12. Further, in the second mold, whether to provide the material being molded into the intermediate molded product W directly from the first shape portion 11 or in the region where the material can flow through the burr forming recess 12 is arbitrarily determined. It is possible to set.

  Further, in the above embodiment, the relief recess 25 is formed in a region connectable to the first shape portion 11, for example, a width of about 1 mm or more around the axis O above the burr forming recess 12, Although the case where it is formed in an annular shape having a depth of about 0.5 mm has been described, the specific shape, width, depth, and other dimensions of the relief recess 25 can be arbitrarily set in accordance with the spirit of the present invention. Needless to say.

  In the above embodiment, the case where the burr forming recess 12 is formed in the first mold (lower mold) has been described. For example, as shown in FIG. Instead of the (lower mold), the burr forming recess 22 is formed in the second mold (upper mold) and the projection F1 is generated by the relief recess 26 formed in the burr forming recess 22. Good. In addition, the code | symbol shown in FIG. 8 is the same as that of the metal mold | die 1 for intermediate molded product manufacture.

  For example, in the above embodiment, the case where the first mold is the lower mold 10, the second mold is the upper mold 20, and the axis O is arranged in the vertical direction has been described. The axis O of the first mold and the second mold may be arranged in the horizontal direction, and the arrangement of the first mold and the second mold can be arbitrarily set.

  Moreover, in the said embodiment, the case where the cylindrical material M in a 1st metal mold | die (lower metal mold | die) shape | molds while the 2nd metal mold | die (upper metal mold | die) descend | falls and the mandrel 30 raises is demonstrated. However, for example, the first mold (lower mold), and the cylindrical material M and the mandrel 30 in the first mold (lower mold) are synchronized (with a speed difference) to synchronize the second mold. It is good also as a structure which shape | molds ascending toward (upper metal mold | die), and a 1st metal mold | die and a 2nd metal mold | die are (speed) with respect to the cylindrical material M mounted in the fixed mandrel 30. It is also possible to form the sheet while lowering synchronously (providing a difference).

  In the above embodiment, the cylindrical portion S1 of the intermediate molded product W1 is sequentially drawn to form the cylindrical portion S1 into a predetermined intermediate dimension corresponding to the stem portion S2, and then the concave portion H1 corresponding to the hollow portion H2. In the above description, the metallic sodium Na is added to the hollow portion H2 and then the opening of the concave portion H1 corresponding to the hollow portion H2 is closed. For example, as shown in FIG. 9, the cylindrical portion S1 has a dimension corresponding to the stem portion S2. In the process of drawing, metallic sodium Na is introduced into the concave portion corresponding to the hollow portion S2, and the cylindrical portion S1 is formed into a dimension corresponding to the stem portion S2, and the concave portion H1 corresponding to the hollow portion H2 is formed. It is good also as a procedure which obstruct | occludes an opening part. In such a case, the manufacturing process shown in FIG.

  FIG. 9 is a diagram for explaining a modification of the manufacturing process of the hollow engine valve. 9 differs from FIG. 1 according to the embodiment in that S16A, S17A, and S18A are used instead of S16, S17, and S18. Since 1) to 5) and 9) corresponding to S10 to S15 and S19 in FIG. 1 described in the above embodiment are the same, the same reference numerals are given and description thereof is omitted. Hereinafter, FIG. 9, S16A, S17A, S18A (corresponding to 6) to 8) in one embodiment) will be described.

  First, when the cylindrical portion S1 is reduced to a specified size by performing drawing with a die Dx, the intermediate molded product W1 is placed in a dry inert gas atmosphere (for example, dry nitrogen gas, etc.) Block-shaped metallic sodium Na (for example, a hexahedron of about 8 to 13 mm on each side) formed in the dimension is introduced into the inside from the upper opening of the recess H1 (step S16A) (corresponding to 6 of one embodiment) .

Next, when metallic sodium Na is introduced into the concave portion H1, the intermediate molded product W1 is subsequently formed in the die Dx + 1 in which holes smaller than the die Dx are formed in a dry inert gas atmosphere (for example, dry nitrogen gas). The cylindrical portion S1 is inserted and drawn to reduce the outer diameter of the cylindrical portion S1 and the inner diameter of the concave portion H1, and the length of the cylindrical portion S1 is extended (step S17A) (7 in one embodiment). )).
At this time, the metallic sodium Na introduced into the concave portion H1 is deformed following the deformation of the concave portion H1 along with the drawing process.

  Next, in the same manner, the drawing process is sequentially performed using a plurality of dies Dn in which the inner diameter is gradually reduced in steps, and the outer diameter of the cylindrical portion S1 and the inner diameter dimension of the concave portion H2 are stepped. And the length of the cylindrical portion S1 is extended stepwise to obtain an intermediate molded product W1 having a prescribed dimension (step S18) (corresponding to 8 of one embodiment).

  According to the mold for manufacturing an intermediate molded product, the method for manufacturing the intermediate molded product, the method for manufacturing the engine valve, the intermediate molded product, and the engine valve according to the present invention, the breakage of the mandrel constituting the mold for manufacturing the intermediate molded product is suppressed. Therefore, it can be used industrially.

V hollow engine valve A umbrella part W intermediate molded product S cylindrical part S2 stem part H concave part H2 hollow part F convex part (convex part protruding from the end face of the umbrella part)
Na Metal sodium M Cylindrical material 1 Mold for manufacturing intermediate molded product 10 Lower mold (first mold)
11 1st shape part 11A umbrella part shaping | molding shape part (1st shape part)
11B Cylindrical part forming hole (first shape part)
20 Upper mold (second mold)
21 End surface molding part (part for molding the end surface of the umbrella part)
25, 25A, 25B, 25C, 26 Recessed recess 30 Mandrel

Claims (7)

In an engine valve manufacturing process for manufacturing a hollow engine valve having a stem portion having a hollow portion formed therein and an umbrella portion formed at one end of the stem portion and having a diameter increasing toward the one end side, A mold for manufacturing an intermediate molded product, forging a heated cylindrical material to mold an intermediate molded product in which a hollow portion, a cylindrical portion corresponding to the stem portion, and a concave portion corresponding to the hollow portion are formed. And
A first mold formed with a first shape part for forming the umbrella part and the cylindrical part;
A second mold for molding the end face of the umbrella part;
A mandrel that is inserted into the first shape part of the first mold and that forms a corresponding recess of the hollow part formed in the cylindrical part,
The second mold is
A mold for manufacturing an intermediate molded product, wherein a relief concave portion for forming a convex portion protruding from an end surface of the umbrella portion is formed in the intermediate molded product in a region connectable to the first shape portion. A mold for producing an intermediate molded product according to claim 1,
The mold for manufacturing an intermediate molded product, wherein the relief recess is formed on a radially outer periphery of an outer peripheral edge of the umbrella portion of the intermediate molded product of the second mold. Corresponding to the stem portion in the process of manufacturing a hollow engine valve comprising a stem portion having a hollow portion formed therein and an umbrella portion formed at one end of the stem portion and having a diameter increasing toward the one end side A method of manufacturing an intermediate molded product having a cylindrical portion, an umbrella portion, and a concave portion corresponding to the hollow portion,
A first mold formed with a first shape part for forming the umbrella part and the cylindrical part;
A second mold for molding the end face of the umbrella part;
A mold for manufacturing an intermediate molded product, comprising: a mandrel that is inserted into the first shape portion of the first mold and that forms a corresponding recess of the hollow portion formed in the cylindrical portion, and is heated to a predetermined temperature. The second mold and the mandrel are moved relative to the cylindrical material, and the umbrella part and the stem part are moved by the first mold and the second mold. And forming the corresponding cylindrical portion and inserting the mandrel into the cylindrical material to form the concave portion corresponding to the hollow portion,
The intermediate is characterized in that it is molded while forming a convex portion projecting from the end surface of the umbrella portion toward the one end side by an escape concave portion formed in a region connected to the first shape portion of the second mold. Manufacturing method of molded products. A method for producing an intermediate molded product according to claim 3,
A method for producing an intermediate molded product, comprising: forming a convex portion formed by the relief concave portion on a radially outer periphery of an outer peripheral edge of the umbrella portion of the intermediate molded product. A method for manufacturing an engine valve using the intermediate molded product according to claim 3 or 4,
Molding the intermediate molded product,
After sequentially drawing the cylindrical portion of the intermediate molded product and molding the cylindrical portion to a dimension corresponding to the stem portion, metal sodium Na is introduced into the concave portion corresponding to the hollow portion,
Alternatively, the cylindrical portion of the intermediate molded product is sequentially drawn, and the cylindrical portion is formed into a dimension corresponding to the stem portion, and metal sodium Na is added to the concave portion corresponding to the hollow portion during the drawing process. The cylindrical part is molded to a dimension corresponding to the stem part,
A method for manufacturing an engine valve, wherein an opening of a concave portion corresponding to the hollow portion is closed.   An intermediate molded product produced by the method for producing an intermediate molded product according to claim 3 or 4.   An engine valve manufactured by the method for manufacturing an engine valve according to claim 5.

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