JPH0373383B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a camshaft which is used to manufacture a camshaft with improved characteristics of at least a cam nose portion or a cam portion and a journal portion.

(Prior Art) Conventionally, as a camshaft used in a valve mechanism of an automobile engine, there is a camshaft having a shape as shown in FIG. 15, for example.

This camshaft 1 has a shaft portion 4 provided with cam portions 2 of a number corresponding to the number of cylinders of the engine and journal portions 3. A method for manufacturing the camshaft 1 in this manner is disclosed in, for example, Japanese Patent Laid-Open No. 57-51202.

FIGS. 16 and 17 are diagrams showing an outline of the method disclosed in the above publication, and show a pre-sintered hollow cam piece 6 and a hollow journal piece 7 that can be fitted into the shaft 5 in a clearance fit relationship.
and the shaft 5 that fixes each piece 6, 7.
The axial position and rotational phase of each piece 6 and 7 with respect to the shaft 5 were determined relative to the shaft 5, on which a plurality of small protrusions 8 having a protrusion amount larger than the gap were provided on the surface of the shaft 5. The camshaft 1 is assembled by fitting the pieces 6 and 7 together in this state, temporarily bonding the pieces 6 and 7 to the shaft 5, and then performing final sintering.
This is the way to obtain.

In the thus obtained camshaft 1, the cam portion and the journal portion, which particularly require wear resistance, are formed from separate members having wear resistance, and the characteristics are partially improved.

However, in such a conventional method, it is necessary to perform preliminary sintering on the cam piece 6 and journal piece 7 before fitting them to the shaft 5, and main sintering after fitting them. In addition to increasing man-hours and increasing costs,
It is necessary to determine the axial position and rotational phase of each piece 6 and 7 relative to the shaft 5, which results in poor productivity and difficulty in positioning with high precision. 5, there was a problem that deflection may occur in the axial direction.

On the other hand, as another example of manufacturing a camshaft, a sintered cam piece (and journal piece) is placed in a predetermined space of a casting mold, and then, for example, molten cast iron is poured into the mold and solidified. There is also a method in which the connecting cam piece (and journal piece) is fixed by being cast (Japanese Patent Application No. 184546/1982).

However, in this method, after installing a large number of sintered cam pieces (and journal pieces) in a mold, molten cast iron is supplied and the cam pieces (and journal pieces) are held accurately until it solidifies. Improvements were needed, and further improvements were desired.

(Object of the Invention) The present invention has been made by focusing on such conventional problems, and it is possible to accurately position a cam part (and journal part) to be integrated into the shaft part of a camshaft. Manufacture of a camshaft that is suitable for mass production due to its high productivity, enables reduction in manufacturing costs, and allows for the production of camshafts with improved characteristics of at least the cam nose portion, cam portion, and journal portion at low cost. The purpose is to provide a method.

(Structure of the Invention) A method for manufacturing a camshaft according to the first aspect of the present invention is that when manufacturing a camshaft in which a shaft part, a cam part, and a journal part are integrated, at least a cam nose part or a cam part of the cam part and journal part are manufactured. and the entire journal part is molded by a molded piece of a wear-resistant material, and the cam part, the parts of the journal part other than the molded piece, and the shaft part are formed of a vanishing model material, and the molding piece and the vanishing model material are made of a vanishing model material. By positioning and integrating the above through the camshaft circumferential positioning part and the camshaft axial positioning part, a disappearing model with a shape corresponding to the shape of the camshaft to be manufactured is manufactured,
The present invention is characterized in that after a mold is manufactured using the vanishing model, molten metal is poured into the mold and solidified to manufacture a camshaft in which the molded piece is integrated.

Further, in the method for manufacturing a camshaft according to the second aspect of the present invention, when manufacturing a camshaft in which a shaft part, a cam part, and a journal part are integrated, at least the cam nose part or the cam part and the journal part are combined. The whole is molded by a molded piece of wear-resistant material, and the parts of the cam part and the journal part other than the molded piece and the outer peripheral part of the pipe-shaped back-up material of the shaft part are formed of a disappearing model material, and By positioning and integrating the piece and the vanishing model material via the camshaft circumferential positioning section and the camshaft axial positioning section, a vanishing model having a shape corresponding to the shape of the hollow camshaft to be manufactured is manufactured, and the above-mentioned The present invention is characterized in that a hollow camshaft in which the molded piece and the pipe-shaped backup material are integrated is manufactured by manufacturing a mold using a vanishing model, and then pouring molten metal into the mold and solidifying it. .

(Example) In this example, a four-cylinder camshaft, which is a valve train component of an automobile engine, will be described as an example.

First, a split mold having a molding space corresponding to the shape of the camshaft to be manufactured is used, and a mold is formed from a wear-resistant material at a position corresponding to the cam nose part in this molding space, and a camshaft circumferential positioning part and a camshaft axial direction positioning part are formed from a wear-resistant material. A cam piece (molded piece) 1 for a cam nose portion having a shape shown in FIG. 2 and having a positioning portion 14a that also serves as a positioning portion.
4, the vanishing model material in a fluid state is press-filled into the molding space by injection or the like to produce the vanishing model 10 shown in FIG. 1 having the same shape as the camshaft. In this case, the manufactured camshaft-shaped vanishing model 10 includes a shaft part 11 and a journal part 1 formed of vanishing model material.
2. It has a cam portion 13, and a cam piece 14 for a cam nose portion made of the wear-resistant material is integrated with the tip of the cam portion 13.

Although wax is often used as the disappearing model material, other plastics such as polyethylene or vinyl chloride, or water-soluble urea resin can also be used.

Further, as the wear-resistant material for the cam piece 14, chilled cast iron, iron-based sintered alloy, fiber-reinforced metal, etc. can be used, but these materials are not particularly limited.

At the same time, a disappearing model having a shape corresponding to the sprue portion and runner portion of the mold to be manufactured later is similarly manufactured using the mold.

Next, the camshaft-shaped disappearing model 10 manufactured above and the disappearing model 18 corresponding to the sprue part 16 and the runner part 17 are brought into a joined state (see FIG. 3), and then installed in the casting flask 20.
The surrounding area is hardened with molding sand 21. At this time, the upper end of the sprue portion 16 is placed slightly above the molding sand 21.

Subsequently, the molten metal of the material constituting the camshaft is poured into the sprue part 16, and the disappearing models 18,1
The shape shown in FIG. 4 is obtained by supplying molten metal while dissipating the cam piece 14 by the heat of the molten metal, solidifying the cam piece 14 by casting it in the molten metal, and removing sand. A camshaft 30 is obtained.

The camshaft 30 obtained here has a shaft portion 31 made of a solidified body of cast molten metal, a journal portion 32, and a cam portion 33.
The cam piece 14 made of the above-mentioned wear-resistant material is integrated into the tip nose portion of the cam piece.

In addition, in the disappearance model 10, the journal part 12
If a ring-shaped journal piece made of a wear-resistant material is installed in the camshaft 30, the journal piece will be integrated with the outer periphery of the journal portion 32 of the camshaft 30 shown in FIG.

5 to 12 are diagrams showing other embodiments of the present invention, of which FIGS.
The figure is a diagram illustrating the disappearing model body used in this example. The disappearing model main body 41 has a tube shape, and is provided with a reinforcing pipe-shaped back-up member 42 on its inner circumferential side, and has a piece positioning portion 43 at a predetermined position on its outer circumferential side.

Such a disappearing model main body 41 is manufactured using a mold having a molding space of the same shape as the disappearing model main body 41, and a pipe-shaped backup material 42 is installed in the molding space, and the pipe-shaped backup material 42 is installed in the molding space. For example, foamed polystyrene is supplied as a disappearing model material between 42 and the molding space, and is foamed and solidified by superheated steam, thereby molding is performed.

In the case of this illustrated example, the piece positioning portion 43 has a protrusion shape, and the cam piece positioning portion 43
a, 43b and journal piece positioning part 43
It consists of c.

FIG. 7 is an explanatory diagram of a slope of a cam piece which is a molded piece, and this cam piece 44 has a predetermined cam surface shape and a hollow hole 44a, and a camshaft circumferential positioning portion 44b is located on the cam nose side of the hollow hole 44a. It has been established. This positioning part 44b is the positioning part 4 for the cam piece.
It has a concave shape with a wide bottom corresponding to the shape of the protrusions 3a and 43b. Further, in this embodiment, the cam piece 44 is made of a wear-resistant iron-based sintered alloy.

FIG. 8 is an explanatory diagram of the slope of the journal piece 45, which has a perfect circular shape and has a hollow hole 45a, and a camshaft circumferential positioning portion 45b is provided in a part of the hollow hole 45a. It is. The positioning portion 45b has a concave shape with a wide bottom corresponding to the protrusion shape of the journal piece positioning portion 43c. Further, in this embodiment, the journal piece 45 is made of a disappearing model material, but like the cam piece 44, it may be a molded piece made of an iron-based material or the like.

Next, in manufacturing the disappearing model, first, the cam piece 44 shown in FIG. 7 is fitted from one end side (the right end side in FIG. 5) of the disappearing model main body 41 shown in FIGS. 5 and 6. Then, positioning in the circumferential direction is performed by engaging the cam piece positioning part 43a at the leftmost end with the positioning part 44b provided on the cam piece 44. Next, as shown in FIG. 10, a bead 46 made of a vanishing material and serving as a cam piece axial positioning member is attached to the boundary between the vanishing model main body 41 and the cam piece 44 to perform axial positioning.

Subsequently, another cam piece 44 is fitted from one end side of the disappearing model main body 41 in the same manner, and the cam piece positioning part 43b provided second from the left end and the camshaft circumferential positioning part 44b provided on the cam piece 44 are engaged. Then, as shown in FIG. 10, a bead 46 made of a vanishing material and serving as a positioning member in the axial direction of the camshaft is attached to the boundary between the vanishing model main body 41 and the cam piece 44. positioning in the axial direction.

Furthermore, the journal piece 45 shown in FIG. 8 is fitted from one end side of the disappearing model main body 41, and the journal piece positioning part 43c provided third from the left end and the camshaft circumferential positioning part 45b provided on the journal piece 45 are fitted. Then, as shown in FIG. 11, the disappearing model main body 41 and the journal piece 4
A bead 46 made of a vanishing material and serving as a positioning member in the axial direction of the camshaft is attached to the boundary with the camshaft 5 to perform positioning in the axial direction.

By fixing a predetermined number of cam pieces 44 and journal pieces 45 in this manner, a disappearing model 50 shown in FIG. 12 is obtained.

At this time, since the pipe-shaped backup member 42 is provided on the vanishing model main body 41, no deformation occurs even when the vanishing model main body 41 has an elongated shape like a camshaft.

Next, when manufacturing a camshaft using such a vanishing model 50, the vanishing model 5
0 and a sprue and runner, which were also formed from the vanishing material, were placed in the flask as in the case of Fig. 3 above, and foundry sand was filled between the flask and the vanishing model. In this state, molten metal is supplied from the sprue to cause the disappearing model body 41 and journal piece 45 to disappear, and at the same time, the molten metal is solidified in the sand mold to obtain a camshaft 60 having the shape shown in FIG.

The camshaft 60 thus obtained has the cam piece 44 integrated into its cam portion, and the wear resistance of the cam portion, which is subjected to a particularly large load, can be improved. Further, the shaft part 61 and the journal part 65 are formed by solidifying the molten metal, but when the journal piece 45 shown in FIG. The piece 45 is integrated.

In FIG. 7, the cam piece 44 is provided with one camshaft circumferential positioning portion 44b on its cam nose side, but as shown in FIG. 14, two or more camshaft circumferential positioning portions 44b are provided.
may be provided, and correspondingly, the disappearing model body 4 may be provided.
Two or more cam piece positioning portions 43a, 43b may be provided on the same circumference on one side as well.

Therefore, as shown in the above embodiment, since the disappearing model main body 41 is provided with the pipe-shaped back-up member 42 therein, even if it has an elongated shape, it will not be deformed during assembly work, transportation, etc. There are almost no In addition, the disappeared model body 4
1 and each piece 44, 45 is a positioning part 43.
Since they are integrated via a to 43c, 44b, and 45b, in the case of the illustrated example, it is possible to completely prevent positional displacement especially in the circumferential direction of the camshaft. Since beads 46 made of vanishing material are attached to the boundaries between the pieces 44 and 45, it is possible to position each piece 44 and 45 in the camshaft axis direction well. Moreover, since the vanishing model 50 is formed in a hollow shape, it is possible to manufacture a hollow camshaft 60, and the weight of the camshaft 60 can be reduced and the valve operating performance can be improved.

In each of the above embodiments, a four-cylinder camshaft, which is a valve train component of an automobile engine, was explained as an example.
Since at least the cam part that receives the most severe load is made of a wear-resistant material, its service life can be significantly extended. The accuracy in circumferential position is extremely good, making it suitable for mass production.
This is an extremely excellent product that allows the production of a camshaft with excellent wear resistance at low cost.

(Effects of the Invention) As described above, according to the method of manufacturing a camshaft according to the present invention, the positioning of the cam portion (and journal portion) to be integrated with the shaft portion of the camshaft is performed by the circumferential positioning portion of the camshaft. It is now possible to perform the process with high accuracy through the camshaft axial direction positioning part, and since it is casting using a vanishing model, productivity is high, making it suitable for mass production and making it possible to reduce manufacturing costs. The very excellent effect that a solid camshaft and a hollow camshaft with improved characteristics of at least the cam nose portion or the cam portion and the journal portion can be manufactured at low cost is brought about.

[Brief explanation of drawings]

Fig. 1 is an explanatory view of the slope of the vanishing model used in one embodiment of the present invention, Fig. 2 is an explanatory view of the slope showing an example of the shape of the cam piece, and Fig. 3 is a mold manufactured using the vanishing model of Fig. 1. FIG. 4 is an explanatory cross-sectional view of a camshaft cast using the mold shown in FIG. 3, and FIGS. Explanatory drawings and vertical cross-sectional illustrations, Figures 7 and 8
9 is an explanatory diagram of the slopes of the cam piece and journal piece used in other embodiments of the present invention, FIG.
Figures 0 and 11 are cross-sectional explanatory diagrams showing how to fix the cam piece and journal piece fitted to the disappearing model body with beads made of disappearing material, respectively, and Figure 12 is a disappearing model manufactured in another embodiment of the present invention. Fig. 13 is an explanatory view of the slope of the camshaft cast using the mold using the disappearing model shown in Fig. 12, Fig. 14 is an explanatory view of the slope showing another example of the shape of the cam piece, and Fig. 15 is the conventional one. Slope explanatory diagram showing an example of the shape of the camshaft from 16th
17 are an explanatory cross-sectional view in the camshaft direction and a cross-sectional view in the perpendicular direction to the camshaft, showing an example of a conventional method of manufacturing a camshaft. 10...Disappearance model, 11...Shaft part, 12
... Journal part, 13 ... Cam part, 14 ... Cam piece (molding piece), 20 ... Casting flask, 21 ...
... Foundry sand, 30 ... Camshaft, 31 ... Shaft part, 32 ... Journal part, 33 ... Cam part, 41 ... Vanishing model body, 42 ... Pipe-shaped backup material, 43 (43a, 43b) ... Cam piece positioning part, 44...cam piece (molded piece), 44b...camshaft circumferential positioning part, 46...bead (camshaft axial direction positioning member), 50...disappearance model, 60...camshaft, 61...shaft Department, 65...Journal Department.

Claims (1)

[Scope of Claims] 1. When manufacturing a camshaft in which a shaft part, a cam part, and a journal part are integrated, at least the cam nose part or the entire cam part and journal part are made of wear-resistant material. At the same time, the cam part and the journal part other than the molded piece and the shaft part are formed of a disappearing model material, and the molding piece and the disappearing model material are formed by a camshaft circumferential positioning part and a camshaft axial positioning part. By positioning and integrating through the parts, a disappearing model with a shape corresponding to the formation of the camshaft to be manufactured is manufactured, a mold is manufactured using the disappearing model, and then molten metal is poured into the mold. A method for manufacturing a camshaft, which comprises manufacturing a camshaft in which the molded pieces are integrated by heating and solidifying the camshaft. 2. When manufacturing a camshaft in which a shaft portion, a cam portion, and a journal portion are integrated, at least the cam nose portion or the entire cam portion and journal portion of the cam portion and journal portion are molded with a molded piece of a wear-resistant material. , a portion of the cam portion and the journal portion other than the molded piece and an outer peripheral portion of the pipe-shaped back-up material of the shaft portion are formed of a vanishing model material; By positioning and integrating via the axial positioning part, a disappearing model with a shape corresponding to the shape of the hollow camshaft to be manufactured is manufactured, a mold is manufactured using the disappearing model, and then a mold is placed in the mold. A method for manufacturing a camshaft, which comprises manufacturing a hollow camshaft in which the molded piece and the pipe-shaped backup material are integrated by pouring and solidifying molten metal.