JPH0796155B2 - Mold for forming cylinder for 2-cycle engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for forming a cylinder for a two-cycle engine, and more particularly to a mold for forming a cylinder for a two-cycle engine having a scavenging port forming portion.

[0002]

2. Description of the Related Art Since a cylinder for a two-cycle engine needs to have a scavenging port communicating with the outside of the machine on its inner peripheral surface, when a cylinder of this type is formed by die casting, Japanese Patent Publication No. 58-31461. Gazette and actual fair 2-312
As seen in Japanese Patent Laid-Open No. 36-36, a slide core for forming a scavenging port is arranged on the peripheral surface of a bore insert, and this is arranged in a direction orthogonal to the axial center by an angular pin that slides in the axial direction in the bore insert. It moves in and out to form a scavenging port on the inner surface of the cylinder.

Generally, in a two-cycle engine, the flow of the air-fuel mixture into the cylinder has a great influence on the scavenging efficiency, that is, the output characteristics of the engine. To give a shape that causes
The device as described above has a problem that it is not possible to form an ideal scavenging port having a curved path because only a linear movement can be given to the slide core.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem in forming a scavenging port, and its object is to provide a new automatic scavenging port capable of automatically forming a scavenging port. To provide a mold for forming a two-cycle engine cylinder.

[0005]

That is, according to the present invention, as a mold for forming a cylinder for a two-cycle engine for achieving such a subject, a nest for forming a bore portion is arranged in one die block so as to be movable back and forth. A scavenging port forming insert is pivotally supported on the insert via a link member, and the scavenging port forming insert is located at the scavenging port forming position when the bore forming insert protrudes.
At the time of retreating, each of them is oscillated and displaced about the pivot point outside the cylinder forming cavity.

[0006]

EXAMPLES Examples of the present invention will be described below. The drawings show one embodiment of the present invention. In the figure, reference numeral 1 is a bore portion forming nest, that is, a bore nest, which has a combustion chamber forming portion 2 at the tip and a bore forming portion 3 at the peripheral surface, and the bore nest 1 includes a bush 7. It is configured to be fitted in the axial center portion of the fixed die block 6 via the above, and driven by a hydraulic cylinder (not shown) to slide back and forth.

Reference numeral 10 denotes a skirt nest integrally attached to the flange portion 4 of the bore nest 1 via a bolt, and a skirt portion forming recess 11 of the cylinder C is provided at the center of the skirt nest 10 on the dividing surface side. Further, in this outer peripheral portion, several inclined nesting support surfaces 12, 12 are provided corresponding to the respective scavenging port P forming positions of the cylinder C.
Are formed radially. The skirt nest 10 also includes a plurality of slits 1 between the scavenging port formation positions.
3 and 13 are formed in a radial pattern, and the pins 14 and 14 provided in these slits 13 have elongated holes 16 respectively.
The link pieces 15 and 15 are pivotally mounted via the shaft so as to be swingable and movable in the longitudinal direction.

The link pieces 15 and 15 are interlocked with the projecting operation of the bore insert 1 when the mold is closed .
A forming nest, that is, a port nest 20 to be described later is projected to a scavenging port forming position, and when the mold is opened, the port nest 20 is retracted in conjunction with the backward movement of the bore nest 1. Pins 17 and 17 provided at the tips of 15 and 15 are guided by inwardly curved guide grooves 18 and 18 formed on the inner surfaces of the lower mold inserts 19 and 19 to form a port insert 20 that pivotally supports the base end. The above movement
It is configured as a pivot that allows the work to be performed .

On the other hand, as shown in FIG. 2, the port nest 20 has its lower surface supported by the nest support surface 12 and occupying the scavenging port forming position when the bore nest 1 is most protruded. Is formed as a positioning surface 21 that abuts against the
An arc-shaped core portion 22 is formed, and the tip of the arc-shaped core portion 22 forms an end surface 23 that contacts the peripheral surface 3 of the bore insert 1.

Reference numeral 25 in the drawing is a nest for forming a water jacket portion fixed to a movable die block 27 by a locking piece 26, and 28 is arranged by a cylinder (not shown) so as to be divided into right and left parts. The split molds for forming the outer peripheral portion of the cylinder are shown.

Next, a cylinder forming process by the apparatus thus configured will be described. First, when the bore insert 1 is projected toward the movable die block 27 side by a cylinder (not shown) under the state before mold closing shown in FIG.
The skirt nest 10 that has risen integrally with this pushes the positioning surface 21 of the port nest 20 by means of the nest support surface 12 and pushes the pins 17 and 17 into the guide grooves 18 and 18.
And pivotally supported port nests 20, 20 are pivoted inward relative to each other, at the end of which they are positioned and supported from below by nest support surfaces 12, 12 as shown in FIG. At the same time, these end faces 23, 23 are brought into contact with the peripheral surface 3 of the bore insert 1. Then, in this state, the movable die block 27 is lowered next, and the split mold 2 is
When 8 and 28 are closed, a cavity for forming a cylinder is formed in the joint surface portion, and the scavenging port nests 20, 2 are formed.
Since 0 is held and fixed, then in this state, the molten metal is injected into the cavity from the sprue 30 to form the cylinder C.

After the step of pouring the molten metal is completed, the bore insert 1 is retracted by a cylinder (not shown).
As shown in FIG. 3, the skirt nest 10 retracted together with the bore nest 1 includes pins 14, 14 and each link piece 1.
5 and 15, the pins 17 and 17 are lowered inward along the guide grooves 18 and 18, and the scavenging port inserts 20 and 20 whose proximal ends are pivotally supported by the pins 17 and 17 are lowered and expanded outward. The core portion 22 at the tip thereof is opened and pulled out from the inside of the scavenging port P created by itself, and these are retracted to the outside of the cavity.

After completing the above operations, finally, referring to FIG.
As shown in FIG. 2, the split molds 28, 28 are divided into right and left by a cylinder, the movable die block 27 is pulled up, and then the cylinder C formed by an ejector pin (not shown) is extruded to complete a series of cylinder forming steps. To do.

[0014]

As described above, according to the present invention, the bore portion forming nest is movably arranged in one die block, and the nest for forming the scavenging port is pivotally provided to this nest through a link. In addition, since the scavenging port forming insert is swingably displaced to the scavenging port forming position when the bore forming nest is projected and retracted to the outside of the cylinder forming cavity when retracting, it is optimal for this nesting. Even if a scavenging port shape is added, it can be freely displaced to the molding position and the retracted position by interlocking with the forward and backward movement of the bore forming nest, making it ideal for a 2-cycle engine on the side of the cylinder. A scavenging port can be formed.

[Brief description of drawings]

FIG. 1 is a diagram showing a mold closing stage of a molding die showing an embodiment of the present invention.

FIG. 2 is a view showing a mold closed state of the above molding die.

FIG. 3 is a view showing a state where a cylinder is molded by the molding die of the same.

FIG. 4 is a view showing a mold release state of the above molding die.

[Explanation of symbols]

 1 Bore Nesting 6 Fixed Die Block 10 Skirt Nesting 12 Nesting Supporting Surface 15 Link Piece 18 Guide Groove 20 Scavenging Port Nesting 25 Water Nest Forming Nesting 27 Movable Die Block 28 Split Type

Claims (1)

[Claims] Claim: What is claimed is: 1. An insert for forming a bore portion is arranged on one die block so as to be movable back and forth, and a link piece is movably attached to the insert for forming a bore portion and movable in a longitudinal direction. The insert for forming the scavenging port is pivotally supported via the
And, nested for scavenging ports formed, the scavenging ports formed position upon projecting the nest for the bore forming, the bore forms
The cylinder forming the cavity out during retraction of the insert for growth, 2 cycle forming die cylinder engine is characterized in that so as to respectively swings to pivot point around.