JP2009293465A - Method for manufacturing hollow valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a hollow valve capable of improving the strength of a head part. <P>SOLUTION: Diameter of a pipe material 20 is reduced with a part of the pipe material 20 left by ironing to form a base section 11a of a stem part 11 and a head part form part 12a in the method for manufacturing the hollow valve 10. An inner diameter of a part of the head part form part 12a is expanded, upsetting of the section of which inner diameter is expanded is repeated to gradually increase an inner diameter of the head part form part 12a and to gradually thicken the inner diameter, and a thick wall part 21 in a shape widened toward an end is formed at the head part form part 12a. The thick wall part 21 is formed in an umbrella shape by hot forging to form the head part 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a hollow valve having a hollow shape used for an intake valve or an exhaust valve of an engine or the like.

  As an intake valve and an exhaust valve used in an engine or the like, a hollow valve is known in which the inside is hollowed to reduce the weight and obtain a cooling effect. This hollow valve is manufactured by cutting or pressing to cut the inside into a hollow.

As an example, Patent Document 1 discloses a molding method by typical deep drawing in press working. In the forming method described here, first, a metal plate is drawn to form a cup member. After that, by pressing the cup member while sequentially changing the punch and the die, it is finally formed so that the thickness of the umbrella part becomes thicker than the shaft part, and the hollow valve is manufactured. It has become.
JP 2001-234714 A

  However, in the hollow valve molding method described above, the shaft portion and the umbrella portion are formed by deep drawing, so that the thickness of the umbrella portion cannot be sufficiently increased and the inner surface is unique to deep drawing. Since wrinkles remain, there was a problem that the strength of the umbrella portion was low.

  Therefore, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing a hollow valve capable of improving the strength of the umbrella.

  A method for manufacturing a hollow valve according to the present invention made to solve the above problems includes a shaft portion and a umbrella portion formed at one end of the shaft portion, and a method for manufacturing a hollow valve having a hollow shape. The pipe material was formed in the thick part forming step and the thick part forming step by forming the pipe material partially thick by performing inner diameter enlargement processing and upsetting processing multiple times on one end side of the pipe material. It has the umbrella part formation process which presses a thick part and forms the said umbrella part, It is characterized by the above-mentioned.

  In this method of manufacturing a hollow valve, first, in the thick part forming step, the pipe material is partially thickened by repeatedly enlarging one end side of the pipe material and upsetting the part. . That is, the inner diameter of the pipe material is expanded by expanding the inner diameter, and the inner diameter enlarged portion is upset to shorten the processed portion and increase the thickness. By repeating such processing, one end side of the pipe material is gradually formed thicker. Thereafter, in the umbrella portion forming step, the thick portion formed in the thick portion forming step is pressed to form the umbrella portion. Thus, since the umbrella part is formed of the thick part formed in the thick part forming step, the thickness of the umbrella part can be sufficiently increased. Thereby, the intensity | strength of an umbrella part can be improved.

  In the method for manufacturing a hollow valve according to the present invention, in the thick portion forming step, the length of the portion of the pipe material subjected to the inner diameter enlargement process is 2.5 times or less the thickness of the pipe material in the portion. It is desirable to set.

  Here, if the part to be subjected to the inner diameter enlargement process is lengthened, the number of processes in the thick part forming process can be reduced, while the part to be buckled during the upsetting process makes the thickness uniform. I can't. Therefore, there is a possibility that skin folding due to buckling remains as an internal defect.

  Therefore, by setting the length of the part to be subjected to inner diameter enlargement processing to 2.5 times or less the wall thickness of the pipe material, while suppressing the increase in the number of processing in the thick part forming process, Therefore, it is possible to prevent the processed portion from buckling and to prevent the internal defect from remaining.

  Moreover, in the manufacturing method of the hollow valve which concerns on this invention, it is desirable to have the process of forming the said axial part by reducing the internal diameter of a pipe raw material by ironing the other end side of a pipe raw material.

  In the inner diameter enlargement process in the thick part forming step, the inner diameter of the pipe material can be increased only by a limited length as described above in one process. For this reason, in order to increase the inner diameter by the length of the pipe material required for forming the umbrella part by carrying out the thick part forming process on the pipe material having the diameter of the shaft part, it is very much Therefore, the production efficiency of the hollow valve is deteriorated.

  On the other hand, the length of the pipe material required for forming the umbrella portion is reduced by one time by forming the shaft portion by ironing the pipe material larger than the diameter of the shaft portion. The inner diameter can be enlarged by processing. Thus, since the number of times of processing can be reduced, the production efficiency of the hollow valve can be improved.

  Further, in the method for manufacturing a hollow valve according to the present invention, the valve body is attached to the back side of the umbrella portion to seal the back side opening of the umbrella portion, and the shaft end member is attached to the end portion of the shaft portion. It is desirable to have an assembling process for sealing the opening of the shaft portion.

  By doing in this way, it becomes possible to select a durable material harder than a pipe material for the shaft end member and the valve body. Therefore, durability of the shaft end member and the valve body can be improved.

  According to the method for manufacturing a hollow valve according to the present invention, as described above, the strength of the umbrella portion can be improved.

  Hereinafter, a most preferred embodiment in which the method for manufacturing a hollow valve of the present invention is embodied will be described in detail with reference to the drawings.

  First, a hollow valve made by the manufacturing method according to the present embodiment will be described with reference to FIG. FIG. 1 is a front view showing a schematic configuration of a hollow valve. This hollow valve 10 is used as an intake valve or exhaust valve of an engine. The hollow valve 10 is provided at the shaft portion 11, the umbrella portion 12 formed at one end of the shaft portion 11, the valve body portion 13 provided at the back side of the umbrella portion 12, and the other end of the shaft portion 11. A groove portion 14 and a shaft end portion 15 are provided. The distal end portion of the shaft portion 11 is composed of a shaft end member 16 formed of a different material from the trunk portion 11 a and the umbrella portion 12 of the shaft portion 11.

  Next, a method for manufacturing the hollow valve 10 will be described with reference to FIGS. 2 and 3 to 11. FIG. 2 is a flowchart showing manufacturing steps of the hollow valve according to the present embodiment. 3-11 is sectional drawing which shows each state in each process of the manufacturing method which concerns on this Embodiment. In the following description, the steps will be described in the order shown in the flowchart of FIG.

  First, “preparing the pipe material” is performed. That is, as shown in FIG. 3, a pipe material 20 having a hollow 20a is prepared. Specifically, a long pipe is cut into a predetermined length (for example, “150 to 300 mm”) and prepared as a pipe material 20. The pipe material 20 thus prepared is provided for the next process. In the present embodiment, the pipe material 20 is made of “SUS316”.

  Next, “formation of the shaft” is performed. That is, as shown in FIG. 4, ironing is performed on a portion of the pipe material 20 that is to be the basic portion 11 a of the shaft portion 11. By this ironing process, the diameter of the pipe material 20 is reduced. Thereby, the diameter of the pipe raw material 20 in the umbrella part formation part 12a which forms the umbrella part 12 can be made larger than the diameter of the pipe raw material 20 in the backbone part 11a of the axial part 11 by one process.

  Next, “formation of thick part” is performed. That is, the inner diameter expanding process and the upsetting process are repeatedly performed on the umbrella part forming part 12a of the pipe material 20, and the umbrella part forming part 12a of the pipe material 20 is formed as in the shapes (1) to (6) shown in FIG. The inner diameter of the slab is expanded to form a thick wall.

  Here, in the inner diameter enlargement process for the pipe material 20, as shown in FIG. 6, a cylindrical punch 32 having a tapered tip is inserted into the pipe material 20 set in the annular dies 30 and 31. Is done. At this time, the outer periphery of the pipe material 20 whose inner diameter is enlarged does not contact the inner peripheral surface of the upper end portion of the die 30 and the inner peripheral surface of the die 31. Then, as shown in FIG. 7, with the punch 32 inserted, an annular punch 33 is fitted between the punch 32 and the die 31, and the punch 33 is lowered to install the pipe material 20. Machining is performed. By the lowering of the punch 33, the length of the pipe material 20 that has been processed to expand the inner diameter is shortened, and the thickness is increased accordingly.

  Then, the pipe material 20 is sequentially changed into the shapes (1) to (6) shown in FIG. 5 by repeating the inner diameter enlargement process and the upsetting process for the umbrella part forming portion 12a of the pipe material 20 while changing the punch and the die. The umbrella portion forming portion 12a is molded (deformed). In this step, finally, as shown in the shape (6) of FIG. 5, a divergent thick portion 21 for forming the umbrella portion 12 is formed in the umbrella portion forming portion 12 a of the pipe material 20. The

  Here, if the length of the portion subjected to the inner diameter enlargement process is lengthened, the number of times of processing in this step can be reduced, while the processing portion is buckled during the upsetting process to make the wall thickness uniform. I can't. Therefore, there is a possibility that skin folding due to buckling remains as an internal defect.

  Therefore, in the present embodiment, the length of the portion subjected to the inner diameter enlargement process is set to 2.5 times or less the wall thickness of the pipe material. That is, in one inner diameter enlargement process, only the length of 2.5 times or less the wall thickness of the pipe material 20 is processed. As a result, it is possible to prevent the machining part from buckling during upsetting while minimizing the number of machining operations (inner diameter expansion and upsetting) in this process, so that skin folding due to buckling is an internal defect. There is no fear of remaining. Further, it is possible to prevent processing cracks from occurring during the inner diameter enlargement processing. Therefore, the thick portion 21 shown in the shape (6) of FIG. 5 can be reliably formed.

  Moreover, in this process, since the inner diameter enlargement process and the upsetting process are repeated a plurality of times, work hardening occurs in the pipe material 20. Therefore, depending on the case, intermediate annealing may be performed during this step. This intermediate annealing can alleviate the hardness of the work-hardened pipe material, so that it is possible to reliably prevent the occurrence of work cracks during the work.

  Next, “formation of umbrella” is performed. That is, by forging the pipe material 20 in which the thick wall portion 21 is formed in the previous process while heating at a predetermined value between the upper forging die 35 and the lower forging die 36 as shown in FIG. The thick portion 21 is formed into an umbrella shape to form the umbrella portion 12. At this stage, a rough shape (rough shape) of a part of the shaft portion 11 and the umbrella portion 12 of the hollow valve 10 is obtained. Thus, since the umbrella part 12 is formed by the thick part 21 formed in the previous process, the thickness of the umbrella part 12 can be made sufficiently thick. Therefore, the strength of the umbrella part 12 can be improved. In addition, the heating temperature at the time of forging is a temperature around “1200 ° C.”. This temperature is lower than the melting point of the pipe material 20 and higher than the transformation point.

  Next, “part assembly” is performed. That is, as shown in FIG. 9, the valve body 17 is attached to the back side opening 12 b of the umbrella portion 12 to seal the opening 12 b, and the shaft end member 16 is inserted into the one end opening 11 b of the shaft portion 11 opposite to the umbrella portion 12. To close the opening 11b. In the present embodiment, the valve body 17 is formed by cutting using “SUH35” as a material. The shaft end member 16 constitutes a part of the shaft portion 13, has the same outer diameter as the outer diameter of the shaft portion 13, and is formed in a rod shape using “SUH1” as a material. A small diameter portion 16 a is formed at one end portion of the shaft end member 16. The small diameter portion 16a is formed to have substantially the same size as the inner diameter of the one end opening 13b of the pipe material 20.

  As described above, it is possible to select a durable material harder than the pipe material 20 for the shaft end member 16. As a result, the durability of the shaft end portion 15 can be improved. That is, durability can be improved by making the shaft end portion 15 harder than other portions. Therefore, high wear resistance can be ensured for the tip surface of the shaft end portion 15 that frequently comes into contact with the rocker arm, the valve lifter or the like.

  Next, “part welding” is performed. That is, as shown in FIG. 10, the end portion of the umbrella portion 12 and the valve body 17 are joined by welding W1, and the end portion of the shaft portion 11 and the outer periphery of the small diameter portion 16a of the shaft end member 16 are joined by welding W2. . Thereby, the crude product of the hollow valve 10 is obtained. The crude product hollow 20a is filled with air as a refrigerant.

  Finally, “finishing” is performed. That is, by cutting and grinding the crude product shown in FIG. 10, as shown in FIG. 118, the final shape of the hollow valve 10 is obtained, and finishing with dimensional accuracy and surface roughness is performed. At this time, the groove portion 14 and the shaft end portion 15 are formed in the shaft end member 16. In this way, the hollow valve 10 shown in FIG. 1 is obtained.

  As described above, according to the method for manufacturing the hollow valve 10 according to the present embodiment, the diameter of the pipe material 20 is reduced by squeezing the pipe material 20 to leave a part of the pipe material 20, and the shaft portion 11. The core portion 11a and the umbrella forming portion 12a are formed. Then, by repeatedly processing the inner diameter of the umbrella portion forming portion 12a and upsetting the portion, an end-spreading thick portion 21 is formed, and the thick portion 21 is formed into an umbrella shape by hot forging. Part 12 is formed. Therefore, since the umbrella part 12 is formed by the thick part 21, the thickness of the umbrella part 12 can be made sufficiently thick. Therefore, the strength of the umbrella part 12 can be improved.

  It should be noted that the above-described embodiment is merely an example and does not limit the present invention in any way, and various improvements and modifications can be made without departing from the scope of the invention. For example, in the above-described embodiment, the member assembled to the one end opening 11b of the shaft portion 11 is the relatively long shaft end member 16, but this member 16 is a short including only the groove portion 14 and the shaft end portion 15. A shaft end member may be used.

  In the above-described embodiment, air is filled in the hollow 20a of the hollow valve 10 as a refrigerant. However, a sodium-based refrigerant may be filled instead of air. Thereby, the cooling effect of the valve can be enhanced.

It is a front view which shows schematic structure of a hollow valve. It is a flowchart which shows the manufacturing process of a hollow valve. It is sectional drawing which shows a pipe raw material. It is sectional drawing which shows the pipe raw material which formed the axial part. It is sectional drawing which shows the shape change of the umbrella part formation part in the process of forming a thick part. It is sectional drawing which shows the state which is performing the internal diameter expansion process. It is sectional drawing which shows the state which is performing upsetting. It is sectional drawing which shows the state which is performing the hot forging in the process of forming an umbrella part. It is sectional drawing which shows component assembly. It is sectional drawing which shows component welding. It is sectional drawing which shows finishing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hollow valve 11 Shaft part 11a Main part 11b of shaft part One end opening 12 Umbrella part 12a Umbrella part formation part 12b Back side opening 13 Valve body part 16 Shaft end member 17 Valve body 20 Pipe material 20a Hollow 21 Thick part 30 Die 31 Dice 32 Punch 33 Punch 35 Forging upper die 36 Forging lower die

Claims (4)

In a manufacturing method of a hollow valve comprising a shaft portion and an umbrella portion formed at one end of the shaft portion, and forming a hollow shape,
A thick part forming step of forming the pipe material partly thick by performing inner diameter enlargement processing and upsetting processing a plurality of times on one end side of the pipe material,
A method for manufacturing a hollow valve, comprising: forming an umbrella part by pressing the thick part formed in the thick part forming step into an umbrella shape by pressing. In the manufacturing method of the hollow valve of Claim 1,
In the umbrella forming step, it is desirable that the length of the portion of the pipe material to be subjected to the inner diameter enlargement processing is set to 2.5 times or less the thickness of the pipe material in the portion.
A method for manufacturing a hollow valve, characterized in that: In the manufacturing method of the hollow valve according to claim 1 or 2,
A method for manufacturing a hollow valve, comprising a step of forming the shaft portion by reducing the inner diameter of the pipe material by ironing the other end side of the pipe material. In the manufacturing method of any one hollow valve as described in any one of Claims 1-3,
A valve body is attached to the back side of the umbrella portion to seal the back side opening of the umbrella portion, and an assembly step is provided to attach a shaft end member to the end portion of the shaft portion to seal the opening of the shaft portion. A method for manufacturing a hollow valve.

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