JP3099533B2 - Three-piece core for piston - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-piece core for a die-casting piston.

[0002]

2. Description of the Related Art As a prior art according to the present invention, there is a three-piece core used for a die casting piston shown in FIG.

In the drawing, P is a cavity for casting a piston, 1 is a center core of a three-piece core, 2 is a left side core, and 3 is a right side core.

FIG. 11 is an explanatory view showing each step of casting a piston using the three-piece core.

FIG. 1A shows a state immediately after a three-piece core is inserted into a mold, integrated and cast. (B), the center core 1 is lowered by the operation of the hydraulic cylinder 4,
(C) Next, the right side core 3 moves leftward by the hydraulic cylinder 5, (d) lowers the right side core, (e) moves the left side core rightward by the hydraulic cylinder 7, and the piston P is taken out. The three-piece core is integrated again, and the steps (a) to (e) are repeated.

[0006]

However, in the casting method using the three-piece core, the upper part 2a and 3a of the side core is thin as shown in FIG. Easy to occur.

As shown in FIGS. 11 (b) to 11 (e), after the center core 1 is pulled out, a plurality of operating cylinders for pulling out the side cores 2 and 3 into a slide are required. Since the moving amount is very large, a large space is required for the equipment. This is shown in FIG.

Further, in the case of die casting, there is a problem that the three-piece core can be used for die casting but cannot be used for die casting, because the product has a strong bite against the mold.

According to the present invention, there is no warpage of a core or the like even when casting is performed using a three-piece core in die casting, and the number of cylinders for moving the split core is reduced to reduce the entire casting apparatus.
Another object of the present invention is to provide a three-piece core of a piston that can be used for die casting.

[0010]

Technical means for solving the above-mentioned problems are as follows.

In the structure of a three-piece core consisting of a center core used for piston casting and right and left side cores, a convex slide piece is provided at the center of both inclined side surfaces of the center core. A slide groove is provided at the center of the inclined inner surface of the both side cores, the slide piece and the slide groove are fitted, and when the center core moves upward, both side cores can move to the center. This is a three-piece core for a piston in which an undercut groove for forming a rib of a piston skirt is provided on the outer periphery of the center core and both side cores.

[0012]

The slide piece provided on the inclined surface of the center core and the slide groove provided on the inner inclined surface of both side cores are fitted together. The die can be cut even in the shape of the cut.

[0013]

Embodiments will be described below.

FIG. 1A is a sectional view of a three-piece core, where 1 is a center core, 2 is a right side core, and 3 is a left side core. Both sides of the center core 1 have an inclined surface 1d, a slide 1a at the center thereof, and a cooling water circulation supply passage 4.

As shown in FIGS. 3 and 4, a slide piece 1a is provided at the center of both sides of the center core 1, and a slide groove 2a is provided at the center of the inner side surface 2d of the side core. The slide piece 1a and the slide groove 2a can slide freely, and 5 is an undercut portion for a skirt inner diameter rib arranged inside the piston skirt when cast.

FIG. 2 is a sectional view taken along the line BB of FIG. 1 and shows a state where the center core 1 and the side core 2 are fitted.

FIG. 5 shows a step of casting a piston with the center core 1 and the side cores 2 and 3 (movement of the apparatus is omitted). Indicates that the split core A fitted and integrated descends to the mold 6 by the action of the hydraulic cylinder. Reference numeral 7 denotes a hollow portion of the mold.

FIG. 2B shows a state in which the split core A is inserted into the mold 6 and the solution 8 is injected into the cavity.

(C) shows the center core 1 of the split core A
When only the hydraulic cylinder is lifted, the side cores 2 and 3 slightly move inward as shown by arrows 9a and 9b by the action of the slide piece 1a and the slide groove 2a, and the mold 6 and the side cores 2 and 3 Gap 1 between
0 results. This eliminates the problem of taking out the split core even if there is an undercut portion.

(D) The split core A moves upward in the mold, the mold 6 moves left and right, and the piston P is cast.

The center core and the side core of the raised split core are then integrated, and the process proceeds to step (a).

FIG. 7 shows the state of the split core A.
FIG. 7A shows the split core A of FIG. 5A as viewed from below, and FIG. 7B shows the split core of FIG. 5D. This shows a state in which the side core has risen and the side core has moved toward the center.

The split core of this embodiment requires only a hydraulic cylinder for raising the center core. For the vertical movement of the side core, the hydraulic cylinder of only the side core moves sideways in conjunction with the movement of the mold and the like. This is unnecessary because there is no space, and the space of the entire casting apparatus is reduced.

In the die casting, the conventional three-piece core system cannot be used because the moving amount is large. Therefore, an integrated core is used. FIG. 8A shows a cross-sectional view of FIG. 8A.

On the other hand, the three-piece core according to the present embodiment is provided with a groove corresponding to a rib as shown at 5 in FIG. 3, so that the cross section of the piston using this core is shown in FIG. ), And its cross section is shown in FIG. 8 (b).

As shown in FIGS. 6 (b) and 8 (b), a rib can be provided inside the piston skirt, and the strength of the piston skirt can be increased to cope with an increase in engine power.

FIG. 6 shows that undercut is possible.
The upper portion of the piston boss shown in 8a of FIG. 8B and 8b of FIG. 8B can be cut off, and the weight of the piston can be reduced.

[0028]

The present invention has the following effects.

In the three-piece core, since the center core and both side cores are separated by sliding the groove of the slide piece, the mechanism is simple and the movement is small, so that it can be used as a split core for die casting. In addition, it is possible to cast a piston having good size and grain size without forming burrs and the like, and capable of forming an undercut.

[Brief description of the drawings]

FIG. 1 is a sectional view of a three-piece core according to the present embodiment.

FIG. 2 is a cross-sectional view showing a fitting state of a slide portion between a center core and a side core.

FIG. 3 is a side external view of a center core with a part omitted.

FIG. 4 is an inner appearance view of a right side core.

5 (a) is a process before casting, FIG. 5 (b) is a process during casting, and FIG. 5 (c) is a process in which only the center core is raised and the side core is slightly moved to the center. (E) shows a step in which the split core has risen.

FIG. 6A is a cross-sectional view of a conventional piston with an integral core, and FIG. 6B is a cross-sectional view of a piston having ribs formed inside a skirt according to the present embodiment.

FIGS. 7A and 7B are diagrams showing the state of the split core according to the present embodiment, where FIG. 7A is a view of the center core and the side core as viewed from below when the center core and the side core are integrated, FIG. It is the figure which looked at the upper part from the lower part when both side cores moved to the center.

8A is a horizontal cross-sectional view of a piston that is die-cast by a conventional integrated core, and FIG. 8B is a horizontal cross-sectional view of a piston that is die-cast by a three-piece core according to the present embodiment.

FIG. 9 is a sectional view of a conventional three-piece core.

FIG. 10 is an enlarged sectional view of the center core and both side cores of FIG. 9;

FIG. 11 is a simplified explanatory view of each casting process using a conventional three-piece core.

FIG. 12 is an overall view of a conventional casting apparatus equipped with a three-piece core.

[Explanation of symbols]

 Reference Signs List 1 center core 1a slide piece 1b slope 2 side core 2a slide groove

Claims (2)

(57) [Claims] In the structure of a three-piece core comprising a center core and both side cores used for piston casting, a convex slide piece is provided at the center of each of the inclined side surfaces of the center core. A three-piece core for a piston in which a slide groove is provided at the center of the inclined inner surface of the side core, the slide piece and the slide groove are fitted, and both side cores can move to the center when the center core moves upward. To 2. A distal outer peripheral portion of the center core and both side cores of the three divided core, in that the formation of the groove undercut to form a rib of the piston skirt
The three-piece core for a piston according to claim 1, wherein