JPH0645060B2 - Molding equipment for camshafts - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold device for a camshaft used in a multi-cylinder engine of an automobile or the like, and more particularly to an ellipse pre-machined in a cavity corresponding to the cam portion. The present invention relates to a mold device for a camshaft, in which an annular cam piece is installed and cast, and thereby the cam piece and the casting are integrally welded.

(Prior Art) As a conventional technology, there is one described in JP-A-56-39365.

That is, as shown in FIG. 4, the upper mold 1a is divided into upper and lower parts.
A column-shaped cavity 2 extending in the horizontal direction (horizontal direction in FIG. 4) is formed on the mating surface of the split mold 1 composed of the lower mold 1b and the upper and lower molds 1a and 1b, and the axial direction of the cavity. A large-diameter and elliptical cam piece fitting hole 2a, 2a that expands radially outward from a part is formed with an upper half and a lower half, and these cam piece fitting holes 2a, 2a are
Fit the elliptical and annular cam pieces 4, 4.

As shown in FIG. 5, the cam pieces 4 and 4 have a thick-walled fixing piece 5 extending in the axial direction on the inner peripheral portion thereof so as to project in a tooth shape at a predetermined pitch in the circumferential direction. .

Then, a sprue 3 communicating with one end (right end) of the cavity 2 is formed at one end of the upper mold 1a, and molten metal is poured into the cavity 2 from the spout 3 to generate the melt as shown in FIG. There is a camshaft casting mold device that integrally joins the cam piece 4 to the casting at its inner peripheral portion, that is, the fixed piece 5 portion.

(Problems to be Solved by the Invention) Generally, each elliptic and annular cam piece 4 and 4 which is separated in the axial direction has its top (cam nose) 4a and 4a on the major axis side.
Is required to be deviated by a predetermined angle with respect to the axial center, that is, the phase is shifted, but in the above-mentioned conventional one, each cam piece fitting hole 2a.
Since the upper half and the lower half of 2a are formed, in order to prevent undercut of each cam piece fitting hole 2a, 2a,
Since it cannot be formed into a regular shape, there is a drawback that rotation allowances of the cam pieces 4, 4 are generated, and it becomes impossible to position them with high accuracy.

SUMMARY OF THE INVENTION It is an object of the present invention to obtain a new camshaft casting mold device that overcomes the above drawbacks.

(Means for Solving Problems) The present invention is configured as follows to achieve the above object.

That is, in a split mold formed by accumulating a large number of split molds in series, columnar cavities extending in the stacking direction over each split mold are formed, and at least a part of the split molds has a mating surface portion having the above-mentioned structure. An elliptical cam piece fitting hole that expands radially outward from the cavity is formed, and an elliptical and annular cam piece whose outer peripheral shape follows the inner peripheral shape of the cam piece fitting hole is provided, and the cam piece is fitted with the cam piece. It is configured to fit into the hole.

(Operation) Since the present invention is configured as described above, the elliptical cam piece fitting hole formed in the mating surface portion of the split mold is continuous in the predetermined split mold in the circumferential direction.

Then, the elliptical and annular piece arranged in the cam piece fitting hole is held such that its major axis side is accurately positioned in a predetermined direction with respect to the axial center of the cavity.

(Example) Hereinafter, the Example of this invention is described based on drawing.

In the drawings, FIG. 1 is a cross-sectional view of a mold device to which the present invention is applied, FIG. 2 is a cross-sectional view of a piece installed in its cavity, and FIG. 3 is a main part showing a welding state between the piece and a casting. It is an expanded sectional view.

In FIG. 1, reference numeral 10 is a mold for molding a camshaft for a multi-cylinder engine.
a ... Stacked vertically.

In the mold 10, a vertically extending camshaft molding cavity 11 and a preparatory chamber 15 that extends vertically in parallel with the cavity 11 and communicates with the lower portion of the cavity 11 at the lower end are formed. .

Part of the split mold 10a forming the cavity 11
A large-diameter, elliptical cam piece fitting portion 12, a large-diameter, annular gear piece fitting portion 13 and a journal portion 14 are formed at predetermined intervals in the vertical direction on the mating surface portion of 10a. An elliptical and annular cam piece 16 and a true cylindrical gear piece 17 are fitted and locked in the portion 12 and the gear piece fitting portion 13.

The cam piece 16 and the gear piece 17 are made of spheroidal graphite cast iron of the same material as the molten metal poured into the cavity 11, and have an outer peripheral shape of the cam piece fitting portion 1 as shown in FIG.
2 and an inner peripheral wall 18a of an annular main body 18 along the inner peripheral shape of the gear piece fitting portion 13, a thin and annular fixing piece 19 protruding in the axial direction is formed.

The fixing piece 19 has, for example, an outer diameter of about 60 mm and an inner diameter of about 40 mm.
The inner peripheral wall of the main body (16, 17) consisting of is approximately 0.
The width is 2 to 1.5 mm, and the width in the axial direction is about 5 mm. In this case, the thickness of the fixing piece 19 may be formed in a taper shape that gradually becomes thinner toward the axis.

Further, a sprue 11 a communicating with the upper part of the cavity 11 is formed in the upper part of the mold 10.

Then, each cam piece fitting portion 12 of the cavity 11
After fitting the cam piece 16 and the gear piece 17 to the gear piece fitting portion 13, the molten metal is poured from the sprue 11a.

According to the above embodiment, the cam piece fitting portion 12 and the gear piece fitting portion 13 are continuously formed in the circumferential direction at the mating surface portion of the predetermined split mold 10a.

Therefore, in particular, each cam piece fitting portion 12 does not depend on the dividing direction of each split mold 10a.
The major axis side can be set to be deviated (phase shifted) from each other in a predetermined direction with respect to the axis of the cavity 11.

Further, each cam piece 16 fitted into each cam piece fitting portion 12 has an elliptical outer peripheral portion thereof.
Since it abuts along the inner peripheral portion of 2, the direction of the long axis is
This coincides with the direction of the major axis of each cam piece fitting portion 12.

If the molten metal is poured from the sprue 11a in this state, the molten metal first passes through the cavity 11 and flows into the auxiliary chamber 15, and while gradually flowing into the auxiliary chamber 15, the molten metal gradually moves from the downstream side to the upstream side of the cavity 11. It will be filled toward 11a.

In this case, since the fixing pieces 19 of the cam pieces 16 and the gear piece 17 are projected to the axial center portion of the cavity 11, that is, the molten metal flow path, the fixing pieces 19 are formed in the cavity 11.
It is immersed in high temperature molten metal passing through for a long time and heated sufficiently,
As a result, as shown in FIG. 3, the surface layer portion (a) of the fixed piece 19 is melted and welded by the new molten metal that has reached the fixed piece 19 part.

In the present invention, the spare chamber 15 may be omitted.

(Effects of the Invention) As is apparent from the above description, the present invention forms a columnar cavity in a divided mold in the direction of its integration,
An elliptical cam piece fitting hole was formed in the mating surface of the split mold, and an elliptical and annular cam piece was fitted in this cam piece fitting hole. With respect to the above, there is an effect that it can be integrally welded to the casting while being accurately positioned in a predetermined direction.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mold device to which the present invention is applied, FIG. 2 is a cross-sectional view of a piece installed in its cavity, and FIG.
The figure is an enlarged cross-sectional view of the essential parts showing the welding state of the piece and the casting,
FIG. 4 is a cross-sectional view of a casting mold device showing a conventional example, FIG. 5 is a cross-sectional view of a piece installed in its cavity, and FIG. 6 is a cross-sectional view showing a welded state of the piece and a casting. 10: mold, 11: cavity, 11a: sprue, 12:
Cam piece fitting part, 13: Gap piece fitting part, 14: Journal part, 15: Preliminary chamber, 16: Cam piece, 17:
Gear piece, 18: main body, 18a: inner peripheral wall, 19: fixed piece, (ii): surface layer portion.

Claims (2)

[Claims] 1. A split mold formed by accumulating a large number of split molds in series is provided with a columnar cavity extending in the stacking direction over each split mold, and at least a part of the split molds is combined. An elliptical cam piece fitting hole that expands radially outward from the cavity is formed in the surface portion, and an outer peripheral shape is provided with an elliptical and annular cam piece that follows the inner peripheral shape of the cam piece fitting hole. A mold device for a camshaft, which is fitted in a cam piece fitting hole. 2. The mold for a camshaft according to claim 1, wherein the cam piece is formed by forming a plate-shaped fixing piece inwardly on a part of an inner peripheral wall of the cam piece. apparatus.