JPS58132325A - Manufacture of hollow cam shaft - Google Patents

Abstract

PURPOSE:To obtain a hollow cam shaft which has sufficient rigidity, strength and accuracy, by utilizing a hollow cam shaft formed by bulge working, as a forming die, inserting other metallic pipe into its inside, and performing the bulge working. CONSTITUTION:A steel pipe 1 of a metallic pipe which has performed drawing to the tip in advance is placed on a die 3, and the tip drawn part is closed by a stopper 5. A punch 4 and the die 3 are formed as one body, and to the rear end of the steel pipe 1, a pressurized liquid injecting nozzle 6 is made to press- contact, and a pressurized liquid is injected. The steel pipe 1 bulges to the outside in the recessed part of the punch and the die, and the first hollow shaft 12 provided with a cam part, a journal part and a shaft part is formed. Subsequently, the stopper 5 is moved backward, also the nozzle 6 is shunted, a steel pipe 13 of other metallic pipe is inserted into the first hollow shaft 12, a drawing part 14 is closed by the stopper 5, and from the nozzle 6, the pressurized liquid is injected. The steel pipe 13 bulges out to the inside surface of the first hollow shaft 12, by which the second hollow shaft is formed, and desired hollow shaft is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a hollow camshaft.

In recent years, with the aim of reducing the weight of camshafts and improving productivity, metal pipes such as steel pipes are placed in molds and bulged to partially bulge outward to form cam parts.
A hollow camshaft in which a journal portion is formed has been proposed.

However, due to molding accuracy and the hydraulic pressure generation device for bulge processing, the wall thickness of the metal tube that can be used is about 1.2 to 2.3 mm, and it is particularly difficult to use as a camshaft for automobiles. However, there was a disadvantage that the strength was insufficient.The present invention was made in order to solve the above-mentioned disadvantages of the conventional method, and uses the hollow camshaft formed by the bulging process as a mold, and has another mold inside it. A hollow camshaft is created by inserting a metal tube and applying bulge processing.The multi-tube structure not only provides sufficient rigidity and strength, but also allows the metal tube to be thicker than conventional ones. It is an object of the present invention to provide a method for manufacturing a hollow camshaft that is usable, inexpensive, and capable of producing a highly accurate hollow camshaft.

Next, a method for manufacturing a hollow camshaft according to the present invention will be explained based on examples. , Figures 1 to 6
The figure shows the manufacturing process of the first embodiment of the present invention.

First, a steel pipe 1, which is a metal tube whose tip has been previously drawn, is placed on a lower die 3, and the tip drawn portion 2 is closed with a stopper 5 (FIG. 1). Then, replace the upper mold 4 with the lower mold 3.
The pressure liquid injection nozzle 6 of the hydraulic pressure generator is connected by pressure to the rear end f of the steel pipe 1 (FIG. 2). Note that the portions of the upper die 4 and the lower die 3 where the steel pipe 1 is located are connected to the desired cam portion 7, journal portion 8, and shaft portion 9.
Recesses 10, 11, and 12 are formed in accordance with the outer shape t.

After that, the pressure liquid (approximately 10
00Kg/cd), the steel pipe 1 is injected into the upper mold 4.
．． The concave portions 10, 11 and 124 of the lower die 3 bulge outward by one inch, and the cam portion 7. A first hollow shaft 12 is formed with a journal part 8 and a shaft part 9 (FIG. 3).

Next, after retracting the stopper 5 a little and retracting the nozzle 6, a steel pipe 1, which is another metal pipe with a drawn end, is inserted into the first hollow shaft 12.
3 and close the drawing part 14 with the stopper 5 (Fig. 4), then press the nozzle 6 to the rear end of the steel pipe 13 and inject the pressure liquid. That is, the steel pipe 13 is partially bulged out using the inner surface of the first hollow shaft 12 as a mold to form the second hollow shaft 15.

Press and laminate the inner surface of the first hollow shaft 12.

A desired hollow camshaft 7)A can be obtained (FIG. 5).

In addition, in the hollow camshaft Al, the second hollow shaft 15 is crimped to the inner surface of the first hollow shaft 12, and the presence of the cam portion 8 has sufficient bonding strength. In order to further improve the bonding strength, when inserting the steel pipe 13 into the first hollow shaft 12, Natsuko uses a soldering foil (brass soldering, phosphor copper soldering, silver soldering) 16 of approximately 0.1 nm thickness as shown in Fig. 4. It is sufficient to wind it at least partially as shown in the figure. The hollow camshaft A obtained as described above is subjected to heat treatment (carbonitriding, gas nitrocarburizing, high-frequency heat treatment) to impart wear resistance to the cam portion 7, journal portion 8, etc. The stamped foil 16 melts at the heat treatment temperature, and the first. Second hollow shaft 12.
15 will be firmly joined. Instead of wrapping the soldered foil 16, copper plating may be applied.

Next, a second embodiment of the present invention will be described with reference to FIGS. 7 to 9.

In this embodiment, the recesses 10 of the upper mold 4 and the lower mold 3 in the first embodiment E are used. Place the ring-shaped cam member 17 and journal member 19 made of cast iron or hard sintered alloy in advance of IIG, and remove them by bulge machining as described above! The first camshaft is a hollow camshaft A equipped with a cam part and a journal part (Fig. 7).

In this case, the cam member 17 and the journal member 19
As shown in FIG.
1 is preferably a non-circular hole to securely fix the cam member 17 and journal member 19 to the hollow camshaft 7)A.

22 is a shaft end member whose hole shape is also a non-circular hole.

Note that when casting the cam member 17, a metal plate may be provided in the mold to cool the partially cast product, and a chill layer 18 may be formed on the cam member 17 to improve the hardness of this portion.

Further, as in the first embodiment, the first. Second hollow shaft 12
．． 15 may be brazed.

As is clear from the above description, according to the present invention, when manufacturing a hollow camshaft by bulge processing, the shaft itself is made of multiple tubes, and a metal tube is inserted into the hollow shaft that has been subjected to bulge processing on the outside. The bulge process is then performed using the inner surface of the hollow shaft as a mold. That is, since the completed camshaft is hollow, it is lighter in weight than a solid one, and since the shaft itself is made of multiple tubes, its rigidity and strength can be greatly increased compared to a single tube. Moreover, since bulge processing is performed on metal tubes with relatively small wall thicknesses as in the past, not only can the external shape be made with the same precision as in the past, but the first stage can be processed without opening the mold. Since the metal tube is inserted into the hollow shaft to perform the next pulge process, it has the advantage of being easy to manufacture.

[Brief explanation of the drawing]

1 to 5 are process diagrams of the first embodiment of the present invention, FIG. 6 is a front view of the obtained hollow camshaft, and FIG. 7 is a process diagram of the obtained hollow camshaft in the second embodiment of the present invention. Figures 8 (A) and 9 (C) are side views of the cam member and journal member in a continuous state, and Figures 8 (B) and 9 are side views of the hollow camshaft shown in Fig. FIG. 9(b) is a front view. 1.13...metal tube, 3...lower mold, 4.
...Upper mold, 6...Pressure liquid supply nozzle, 7...
...Cam part, 8...Journal part, 12.1
5...Hollow shaft, 17...Cam member,
19...Journal member. Patent applicant: Toyo Kogyo Co., Ltd. Agent
Patent attorney Aohaku Ao and 2 others ~ ~ Procedural amendment form) % type % 1. Indication of the case Patent Application No. 15235 of 1982 2. Name of the invention Method for manufacturing hollow camshafts 3. Person making the amendment Case and Relationship Patent applicant representative Yoshiki Yamazaki 4 agent 146-

Claims (1)

[Claims] (1) A metal tube is placed in a mold and bulged outward by bulge processing to form a first hollow shaft having a cam part and a journal part, and then another metal tube is inserted into the first hollow shaft. A method for manufacturing a hollow camshaft, comprising inserting a pipe and forming a second hollow shaft having a shape along the inner surface of the first hollow shaft by bulge processing to obtain at least a double hollow camshaft.