JPH0256171B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is an assembly in which a hollow steel tube is used as a camshaft for an internal combustion engine, and a separate cam part and, if necessary, a journal part, etc. are fixed thereto by bulge processing or the like. Regarding camshaft.

BACKGROUND TECHNOLOGY Japanese Patent Application Laid-open No. 132325/1983 discloses a double-tube hollow camshaft in which a steel pipe is once bulge-formed and another steel pipe is inserted into the inner periphery of the same to form a bulge.

In addition, as a camshaft that fills the inner circumference of a bulge-formed steel pipe with plastic,
There are issues such as No. 9042.

Furthermore, the hollow camshaft is made of reinforced plastic,
An example of an assembled camshaft in which the cam piece is made of metal and the two pieces are joined with adhesive is disclosed in Japanese Patent Application Laid-Open No. 58-75903.

Problems to be Solved by the Invention Double bulge forming of steel pipes is superior in that it can reduce the wall thickness of each steel pipe and reduce the bulge forming load, but there is a difference in the amount of heat shrinkage during use of the camshaft. As a result, there is a problem that a gap tends to be formed between the inner and outer pipes, and there remains concern regarding the strength reinforcement of the inner circumferential pipe especially at the operating temperature of the camshaft.

Camshafts filled with reinforced plastic are superior in that they can prevent gaps between the inner and outer shafts due to differences in heat shrinkage, but in order to uniformly strengthen the shaft as a whole, it is recommended to use short fiber reinforced plastic. As a result, there is a problem in that the high reinforcing effect of the reinforced plastic cannot be obtained, and especially when the reinforced plastic is filled in a hollow shape to secure oil holes and reduce weight, further strength reduction is unavoidable.

In addition, the method using adhesive means to connect the hollow reinforced plastic shaft and the cam piece is superior in that woven or thread-like long fibers can be used as the plastic reinforcing fibers. There is a problem in that the bonded portion tends to loosen due to differences in heat shrinkage and heat shrinkage.

Means for Solving the Problems A reinforcing tube made of long fiber-reinforced plastic is inserted into the inner periphery of a hollow steel shaft to which a cam piece is connected by expanding its diameter, and the reinforcing tube is joined to the hollow steel tube by expanding its diameter.

Function: A reinforcing tube made of long fiber-reinforced plastic is expanded and joined to the inner periphery of the hollow steel shaft, so that the long fibers lie close to the substantially bellows-shaped inner periphery of the hollow steel tube.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. FIG. 1 shows an embodiment of an assembled camshaft 100, in which 101 is a hollow steel shaft such as a steel pipe.

Cam pieces 120, 121, 122, and 123 and journal pieces 102, 103, and 104 are formed in advance into a desired cam profile and desired cylindrical shape by casting, forging, or sintering. The cam piece and the journal piece have through holes 130, 131, 132 through which the hollow steel shaft 101 (FIG. 3) before diameter expansion can be inserted, and a substantially annular cut on the side surface of each piece connected to its own through hole. Notch part 14
3, 140, 141, 144, 113, and 142 are provided.

These individual notches 140, (141,...)
is formed in a truncated cone shape so as to expand in diameter from the through holes 130, (131, . . .) toward the side surface of the piece. Note that the notches 140, (141, . . . ) are not limited to a linear tapered shape, but may be rounded, such as an arc shape.

In addition, the cam piece 120 and the journal piece 102
Surface treatment such as carburizing treatment is performed as necessary.

Hollow steel shaft 101 of this assembled camshaft 100
The way to connect the cam piece and the journal piece is as follows.
Each piece is fitted into a predetermined position on the hollow steel shaft 101, and then set in a bulge mold (not shown) having a mold surface in a predetermined camshaft shape, and the mold is closed.

Thereby, a pair of mutually opposing notch portions 142, 143, (140, 141) of a journal piece and a cam piece or a cam piece and a cam piece that are adjacent to each other.
creates a pair of enlarged diameter spaces in the projection planes of the opposing notches.

Then, with the mold closed, an emulsion or the like is injected into the hollow steel shaft, and the emulsion is compressed.
Then, the hollow steel shaft 101 expands outward, and the inner peripheral surface of the through hole of each piece 102, 120, the notch 142,
143, (140, 141) and along the mold surface of the bulge mold, plastic deformation occurs as shown in FIG. In particular, a pair of opposing notches 142, 14
3, (140, 141, ...) have gentle bulges 105, 109, 10 common to the notch.
7, 110, 108, 112, and 113 are formed, and the inner peripheral surface of the hollow steel shaft 101 has a substantially bellows shape.

This securely fixes each cam piece and journal piece to the hollow steel shaft, and then the camshaft 100 is removed from the bulge mold.

The prevention of relative rotation between the cam piece 120, journal piece 102, and hollow steel shaft 101 of the camshaft 100 shown in FIG.
2 and the notches 140, 142 are given a polygonal shape, for example, a hexagonal shape as shown in the figure, and the hollow steel shaft 101
This is achieved by expanding the hollow steel shaft through bulge processing, thereby plastically deforming the hollow steel shaft along the hexagonal surface of each piece.
In order to prevent relative rotation between each piece and the hollow steel shaft, small claws (not shown) are provided in the notches, and eccentric shapes (not shown) are provided for the through holes 130 and 132. This can also be achieved by providing a notch.

Furthermore, as shown in the figure, by providing notches 140, 143, (141, 144) on both sides of the cam piece, it is possible to reliably prevent the cam piece from moving in the axial direction, and the notches on both sides of the cam piece By having a difference in size, it becomes easy to prevent the cam piece from being inserted in the opposite direction when inserting the cam piece into the hollow steel shaft.

Next, a reinforcing shaft 160 is attached to the inner periphery of the hollow steel shaft 101 of the camshaft 100 formed as shown in FIG.
The process of molding will be explained with reference to FIG. 7 and FIG.

Note that an air vent hole may be formed at a suitable location on the outer periphery of the hollow steel shaft 101 in preparation for expanding the diameter of the reinforcing tube, which will be described later, if necessary.

First, as shown in FIG.
Insert 0.

This reinforcing tube 160 is prepared in advance by forming it as follows. For example, long fibers of reinforcing fibers may be wound around a mold (not shown) and impregnated with a suitable resin to form a hollow reinforced plastic shaft (so-called filament winding), or a cylindrical shape. It is formed as a hollow reinforced plastic shaft which is formed by inserting a reinforcing fiber woven fabric 150 into the outer periphery of a mold (not shown) and impregnating it with a suitable resin.

Next, the camshaft 100 loaded with the reinforcing tube 160 is fixed in an appropriate mold (not shown), and the reinforcing tube 160 and, if necessary, the hollow steel shaft 101 are heated and subjected to atmospheric or hydraulic pressure. By applying internal pressure, the reinforcing tube 160 is expanded in diameter and joined to the substantially bellows-shaped inner circumferential surface of the hollow steel shaft 101.

At this time, the convex portions 161 and 16 of the reinforcing tube 160
If the amount of protrusion of the tubes 2, 163, 164 is insufficient and they do not fully engage with the inner peripheral surface of the bulged portion 111, (105,...) of the hollow steel shaft, reinforcing tube 160 is used to solve this problem. When heating and applying internal pressure, a load is further applied to shorten the reinforcing shaft 160 in the axial direction.

The assembled camshaft 100 shown in FIG. 1 assembled in this way has the convex portions 161, 162 (...
), the long fibers also pass through, and the hollow steel shaft 101 and the reinforcing shaft 160 are firmly joined.

In addition, examples of reinforcing fibers for woven fabrics include glass fiber,
Select and use an appropriate material from among carbon fibers, etc., select and use an appropriate material from thermosetting resins and thermoplastic resins for the filling resin, and add shorts to the filling resin if necessary. Fibers may be mixed in to further strengthen the strength.

This assembled camshaft 100 is then taken out from the mold, the cam surface and journal portion are ground, oil holes, etc. are processed, and the desired camshaft is completed.

Effects As described above, according to the present invention, a reinforcing tube made of long fiber-reinforced plastic is expanded and joined to the inner periphery of a hollow steel shaft, and the long fibers are placed close to the substantially bellows-shaped inner periphery of the hollow steel tube. , high strength reinforcement for hollow steel shafts can be achieved.

Therefore, in order to obtain the required camshaft strength, the thickness of the hollow steel shaft can be reduced to facilitate bulge forming.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a partially sectional plan view of an assembled camshaft. FIG. 2 is a sectional view taken along line AA in FIG. 1. 3 to 8 show the parts and assembly process of the assembled camshaft shown in FIG. 1, and FIG. 3 is a partially sectional plan view of the hollow steel shaft. FIG. 4 is a partially sectional elevational view showing a journal piece and a pair of cam pieces. FIG. 5 is a partially sectional plan view of the assembled camshaft after bulge forming. FIG. 6 is a sectional view taken along the line B-B in FIG. 5. FIG. 7 is a partial cross-sectional plan view of the step of expanding the diameter of the reinforcing shaft. FIG. 8 is a sectional view taken along the line CC in FIG. 7. (Explanation of symbols), 100...Assembly camshaft.
101...Hollow steel shaft. 102...Journal piece.
120, 121...Cam piece. 130,131...
Through hole. 150...Reinforced fiber woven fabric. 160...Reinforcement pipe.

Claims (1)

[Claims] 1. In the first step, an annular cam piece 12 prepared in advance
The hollow steel shaft 10 is inserted into the through holes 130 and 131 at 0 and 121.
1, and expand the diameter of the hollow steel shaft 101 to connect the cam piece and the hollow steel shaft. In a second step, a reinforcing tube 160 made of long fiber reinforced plastic is inserted into the inner periphery of the hollow steel shaft 101. The method for manufacturing an assembled camshaft is characterized in that the reinforcing tube 160 is expanded and joined to the hollow steel shaft 101.