JPH0435244B2 - - Google Patents

Description

Detailed Description of the Invention: Industrial Application Field An assembled cam in which a hollow tube is used as a camshaft of an internal combustion engine according to the present invention, and a separate cam part, bearing member, etc. are fixed thereto by bulge processing or the like. Regarding the shaft.

Prior Art An example of an assembled camshaft using this type of bulge processing is Japanese Patent Publication No. 55-46767. Further, as a manufacturing method in which the shaft end members are joined together at the same time during bulge processing, there is disclosed Japanese Patent Application No. 109086/1986 filed by the applicant of the present invention.

Problems to be Solved by the Invention When the shaft end members are joined by bulge processing, it is difficult to obtain a strong connection between the shaft end member and the hollow shaft, and furthermore, when the shaft end members are joined together, the hollow shaft and the shaft end member come into contact with each other. Due to the low reliability of the seals in the parts, there are variations in the joint strength of the shaft end members of the completed assembled camshafts, leaving concerns about quality.

In this regard, since it is impossible to judge the state of connection between the shaft end member and the hollow shaft from its appearance, and non-destructive inspection of the state of connection is also difficult, it is desirable to improve the reliability of the connection strength during the manufacturing process. Ta.

Note that if the fluid pressure during bulge processing is increased in order to increase the joint strength of the shaft end members, the cam piece will be more likely to break, so there is a limit to the fluid pressure. At the pressure level, there was a problem that the reliability of the bonding strength was insufficient as described above.

Means for Solving the Problems: The hollow shaft is inserted and expanded in the axial direction to temporarily fix the shaft end member and the cam piece, and then fluid pressure is applied to securely fix the shaft end member and the cam piece.

Function: As the hollow shaft is inserted and expanded, the hollow shaft comes into contact with the inner periphery of the cam piece, and the hollow shaft is significantly deformed at the axial end where the shaft end member is externally fitted.
Fluid pressurization allows the hollow shaft end, which has high molding resistance and is difficult to mold into a desired shape, to be substantially along the inner periphery of the shaft end member.

Furthermore, by swaging and expanding the hollow shaft, the repulsive force of the hollow shaft is also applied to the abutting portion of the hollow shaft end and the shaft end member, making it possible to achieve a perfect seal therebetween.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. FIG. 1 shows an embodiment of an assembled camshaft 1 together with a bulge mold, in which 2 is a hollow shaft such as a steel pipe, 3 is a cam piece, 4 and 5 are shaft end members, and 6 is a journal piece.

The cam piece 3 is made of cast iron, forged, sintered, or the like to approximately have a desired cam profile, and is provided with a through hole through which the pre-diameter hollow shaft 2 can be inserted.

The through hole is provided with a means, such as a hexagonal cross section, for the purpose of preventing relative rotation after coupling with the hollow shaft.

The journal piece 6 is also provided with relative rotation prevention means similar to the cam piece.

As shown in FIGS. 2 and 3, the shaft end member 4 consists of a journal portion 10 and a gear portion 11, and the journal portion 10 has a center hole 16 and a female thread 17 formed therein.

A bottomed cylindrical hole 12 is formed in the gear portion 11 from its axial end surface.

As shown in FIG. 3, the vicinity of the entrance of this hole 12 is formed into a polygonal hole 13, the purpose of which is to prevent relative rotation after coupling with the hollow shaft.
Note that the shape of the inner circumference near the entrance of the hole 12 does not have to be hexagonal or polygonal in cross section.

An annular recess 14 is formed at the back of the polygonal hole 13 as an annular groove with a semicircular cross section, and its purpose is to prevent relative movement in the axial direction after coupling with the hollow shaft. The annular recess 14 is not limited to a semicircular cross section, and may have other shapes.

A cylindrical hole through which the hollow shaft 2 can be inserted is formed at the back of the annular recess 14, and a shaft end inner bottom surface 15 is formed at the back of the annular recess 14.
is formed.

The other shaft end member 5 is substantially the same as the shaft end member 4 described above, except that it does not have a gear portion and has a hole extending therethrough.

Next, the assembly of the above-mentioned assembled camshaft will be explained with reference to FIG. 4.

First, the bulge mold will be explained.

The bulge mold is divided into upper and lower parts, 20 is an upper mold, and 21 is a lower mold. This upper and lower mold 20,
The outer periphery of 21 is received by mold holders 22 and 23.

The inner circumferences of the upper and lower molds 20 and 21 are carved into the desired camshaft shape, and at both ends of the die-cut, there are a shaft end presser 24 and an injection nozzle 2 that also serves as a shaft end presser.
5 are arranged facing each other.

Note that a coupler 30 is interposed between the injection nozzle 25 and the shaft end member 5 to connect the two.

The shaft end presser 24 and the injection nozzle 25 are configured to be pressed against the hydraulic pressure filling the inner periphery of the hollow shaft 2 by a hydraulic cylinder (not shown).

When assembling the camshaft, first install the hollow shaft 2.
The cam piece 3 and the journal piece 6 are inserted into predetermined positions, and then the shaft end members 4 and 5 are fitted onto the hollow shaft end.

This is then set in a bulge mold, and the mold is closed by applying pressure in the directions of the arrows as shown in FIG.

At this time, the shaft end members 4 and 5 are separated from their positions when the camshaft is completed, but this is because the hollow shaft 2 is made longer by a predetermined amount in anticipation of the reduction in the overall length due to the bulging process, and also because of this. This is to enable press contact between the hollow shaft end surface and the inner bottom surface 15 of the shaft end member at the initial stage of bulge processing, and to achieve a seal therebetween.

Then, with the mold closed, the shaft end holder 24 and the injection nozzle 25 are simultaneously pushed in the direction of compressing the hollow shaft 2 to the position where they are stopped by the molds 20 and 21, a so-called hollow shaft swaging tube expansion. I do.

By this swage expansion, the hollow shaft 2 bulges out at the appropriate location in the outer circumferential direction, and the cam piece 3, journal piece 6, and shaft end members 4, 5 are temporarily fixed.At this point, the entire length of the camshaft 1 is determined, and the hollow shaft 2 The shaft end is the shaft end inner bottom surface 15 of the opposing shaft end members 4 and 5,
15 and is in a state of strong contact.

Next, with the mold closed and the mold closing pressure and swaging pressure maintained, an emulsion or the like is injected into the hollow shaft, and the emulsion is compressed and pressurized, a so-called bulge process.

Then, the diameter of the hollow shaft 2 is enlarged to a small extent as shown in FIG. 1, and the coupling force with the cam piece 3, journal piece 6, and shaft end members 4, 5 is strengthened.

and plastic deformation along the mold surface of the bulge mold.

Particularly, in the inner peripheral portions of the shaft end members 4 and 5, an annular bulge 7 having a hexagonal cross section is formed along the polygonal hole 13, and an annular bulge 7 having a semicircular cross section is formed along the annular recess 14.

Note that the shrinkage in the overall length of the hollow shaft 2 due to this bulging process is extremely small compared to the case where the swaging tube expansion is not performed in advance.

The reason for this is that the overhang formed on the side surface of each piece due to the swaging tube expansion engages with the mouth edge of the piece and shaft end member during bulge processing and resists the reduction in the overall length of the hollow shaft 2. Conceivable.

It is also considered that, as the shrinkage of the hollow shaft 2 is reduced in this way, the protrusion of the hollow shaft into the annular recess 14 of the shaft end member is improved.

As a result, each cam piece, journal piece, and shaft end member are firmly fixed to the hollow shaft.

After taking it out from the bulge mold, the cam surface and journal part are ground and finished if necessary.
The desired camshaft 1 is completed by machining oil holes and the like.

Effects As described above, according to the present invention, when the hollow shaft comes into contact with the inner periphery of the cam piece as the swaging expansion of the hollow shaft progresses, the hollow shaft is moved to the axial end where the shaft end member is externally fitted. The hollow shaft end, which undergoes significant deformation and is difficult to form into the desired shape due to high forming resistance with fluid pressure, can be made to almost follow the inner periphery of the shaft end member. The repulsive force of the hollow shaft is also applied to the contact area between the shaft end and the shaft end member, creating a perfect seal between them, so even if the fluid pressurizing force is reduced when connecting the assembled camshaft, the shaft end can be easily and firmly secured. The members are joined to the hollow shaft, and high joint strength with little variation can be obtained.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a partially sectional plan view of an assembled camshaft that has been assembled within a bulge mold. FIG. 2 is a sectional view of the shaft end member.
FIG. 3 is a sectional view showing the - section of FIG. 2. Fourth
The figure is a partially sectional plan view of each part set in a bulge mold and closed. Explanation of symbols, 1...Assembly camshaft. 2...
hollow shaft. 3...Cam piece. 4, 5...Shaft end member.

Claims (1)

[Claims] 1. Insert the cam piece 3 into the hollow shaft 2 in advance, fit the shaft end members 4 and 5 onto the ends of the hollow shaft, and install them into the molds 20 and 21, and then insert the hollow shaft 2 into both ends in the axial direction. The cam piece 3 and the shaft end members 4 and 5 are temporarily fixed by compressing and expanding the hollow shaft, and then the diameter of the hollow shaft 2 is enlarged to the smallest detail by bulge processing, and the cam is expanded. A method of manufacturing an assembled camshaft, characterized in that the bonding force between the piece 3 and the shaft end members 4 and 5 is strengthened.