JP2579004B2 - Collapsible sand core for cylinder of engine block - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a disintegratable core for die casting (expendable sand).
core).

BACKGROUND OF THE INVENTION Conventional cores for forming a group of coolant jackets surrounding a group of cylinders, such as in an engine block of an internal combustion engine, have projections on their cylindrical sides and have Has no protrusion at the end. Furthermore, if the entire surface of the core is slightly inclined, it is converged from the central projection in both axial directions. Also, there is no connection between the sides of the core group between the plurality of cylinder cores, and therefore the connection between the opposing sides of the plurality of cylinder cores is only at the ends of the cores.

Problems to be Solved by the Invention As described above, the conventional sand core has no strength in handling and is easily broken, and if it is intended to improve heat resistance and pressure resistance (with respect to the molten metal to be poured), it is difficult to improve the heat resistance after casting. It is known that sand release property from castings is poor. Further, it is difficult to reduce the wall thickness of the water jacket of the engine block in order to improve the heat resistance and the pressure resistance described above, and various disadvantages such as a result of impairing the cooling effect of the cylinder are known.

FIG. 1 is a perspective view of a collapsible core 10 for a water jacket of a two-cylinder engine block. In this water jacket, each cylinder consists of a similar hollow truncated cone 12, the tapered end of each truncated cone 12 being supported by legs 14, which are arranged at intervals in the circumferential direction. And an annular ring 16 extending inward. The part surrounded by the truncated cone 12, the tapered end legs 14 and the annular ring 16 is a void, and the melt melts the cylinder liner during die casting using this sand core. Directly insert, increases the strength of the engine block. An annular ring (flange) 16 adjacent to the protruding legs is provided with a bridge 20
As shown in FIGS. 1 and 3, it is preferable that the cylinders are integrally connected, and there is no jacket between adjacent cylinder groups.
Therefore, there is no core between these jackets. If one cylinder jacket core is required, a half core or one truncated cone is formed as a core, and if more than two cylinders of engine block cores are required, the truncated cone shape is used. As shown in FIG. 1, the core extends between two projections by joining together adjacent projections, such as by a bridge 20. As shown in FIG.

FIG. 4 shows the core 10 in the mold cut along the line 4-4000 in FIG. An annular ring 16 on the protrusion is held by a flange 32 extending outwardly of the mandrel 30, which also supports a cylinder liner which is cast into the cylinder of the cylinder block.
The mandrel 30 includes a protruding core leg 14 and an annular ring.
It is disposed on a dowel (holding) 42 of a movable mold 40 having a projection space 44 larger than 16, so that the core is securely held when the mold is closed and It will not be damaged. However, in order to better arrange the core 10 in the mold in the gap between the projection space and the projection of the core, at least one positioning pin 46 is used as an engagement portion of the gap.
It is preferable to have Then, the mandrel 30 is clamped between the movable mold and the fixed mold 50, and the fixed mold is
It also forms part of the crankcase of the engine block formed in 51. Between the dies 40 and 50 are shown a pair of opposing slide dies 52 and 54 which form opposed longitudinal sides of the cylinder group.

It should be understood that the shapes of the truncated cones and cylinders described in this specification need not be circular, but may be non-circular in cross-section, such as elliptical, polygonal, etc. It is.

In addition, if sufficient space is allowed for in the design of the engine block, the water jacket cone 12 may extend between the cylinders to provide additional core strength and additional engine cylinder cooling. it can.

The disintegratable core of the present invention is preferably made of sand which is integrally bonded with an organic resin which decomposes after a molten metal injected into a mold surrounding the core is solidified.

Although the principles of the invention have been described with reference to a particular device, it should be understood that the description is by way of example only and does not limit the scope of the invention.

Effect of the Invention To obtain a better cooling effect of the hottest end of the cylinder, an inclined core with the thinnest wall of the water jacket can be produced.

By connecting adjacent protrusions of the cylinder group integrally, a substantially rigid core can be made when a large number of parallel cylinder groups are made.

In the present invention, since the protruding portion is provided at the tip portion of the collapsible sand core, when setting the sand core in the mold, the protruding portion is inserted into the groove of the mold and held in the mold. It can be held down at the base of the mandrel for holding the cylinder liner. Therefore, the sand core can be reliably and easily installed in the mold. In addition, since this projection is provided at a position outside the product member which does not adversely affect the production of the engine block product, it does not hinder the casting at all, and naturally has no influence on the shape and strength of the cast product. It has no adverse effect and is extremely useful.

In order to better arrange the core of the present invention in the mold, it is possible to provide a core having a reference surface for a positioning pin on a projection of the core.

[Brief description of the drawings]

FIG. 1 is a perspective view of a collapsible core showing an example of the present invention for a water jacket surrounding a pair of cylinders in an engine block, and FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. Showing a projection having an annular flange extending inwardly of the core, supported by a group of spaced projections on the tapered end of the core of the invention on the frustoconical side,
FIG. 3 is a sectional view taken along the line 3-3 in FIG. 1, with a portion of one cylinder removed and the projections of adjacent cylinder jackets of the core of the present invention between adjacent annular flanges. FIG. 4 is a cross-sectional view of the core of FIG. 1 taken along line 4-4, with the core positioned at an appropriate location in the mold to form a jacket in the cylinder block. 2 shows a state before the molten metal is injected in which the slide mold is also engaged. In the figure: 10: collapsible sand core, 12: truncated cone, 14: protruding leg, 16: annular ring (or annular flange), 20
... bridge, 30 ... mandrel, 32 ... outwardly extending flange, 34 ... cylinder liner, 40 ... movable mold, 42 ... dwell, 44 ... ... cavity for protrusion, 46 ... Positioning pin, 50: fixed mold, 52, 54: Opposing slide mold.

Continued on the front page (72) Inventor Robert I. Badenhope United States. Ohio 43623. Toledo. Abt. number. 6 e. West Alexis Road. 3403 (56) References JP-A-61-147945 (JP, A) JP-A-61-237866 (JP, A) Jiko 63-29162 (JP, Y2)

Claims (7)

(57) [Claims] A collapsible sand core for a water jacket surrounding a cylinder of a cylinder block, wherein the sand core is disposed on a tapered end of the sand core for disposing the sand core in a cylinder block casting mold. A collapsible sand core consisting of a hollow truncated cone having a projection. 2. An annular flange, wherein said protrusion extends from said tapered end of said truncated cone in its tapering direction and is circumferentially provided inside a group of legs arranged at circumferentially spaced intervals. The disintegrable sand core according to claim 1, which has: 3. The collapsible sand core according to claim 1, further comprising a surface on an end face of the protruding portion of the sand core that comes into contact with a positioning pin when positioning the sand core in a mold. 4. The collapsible sand core for a jacket surrounding a number of cylinders of a die-cast engine block comprises a number of hollow frusto-conical shapes, and for each cylinder, each frusto-conical shape has an integral protrusion at its tapered end. Disintegratable sand core having a projection connected to the core. 5. The collapsible sand core according to claim 4, wherein said cylinder groups have their axes parallel and aligned in the same plane. 6. An annular flange extending from the tapered end of the truncated cone in the tapered direction and circumferentially provided inside a group of legs arranged at intervals in the circumferential direction. The disintegratable sand core according to claim 4, which has the following. 7. The collapsible sand core according to claim 4, further comprising a surface on the end face of the protrusion of the sand core, the surface contacting a positioning pin when positioning the sand core in a mold.