JPH01154857A - Core for pressure casting - Google Patents

Abstract

PURPOSE:To prevent deformation with simple construction by penetrating a rigid member integratedly forming a core part and a core part connecting with this in a hollow core part and supporting. CONSTITUTION:The core 15 is assembled into cavity 14 for each die 11-13 and the rigid member (core print) 16 is fitted into a recessed part 17 between the upper and lower dies 11, 12 and supported. Then, under this condition, Al alloy (for example, JIS ADC 10) is pressure-cast in the cavity 14. Successively, after cooling this casting, each die 11, 13 is separated to take out the casting and the member 16 is drawn out from the casting and molding sand of the core is discharged to obtain raw casting for a cylinder block. At the time of the above-pressure-casting, the static pressure P with the molten metal in a cavity 14 is developed and acted to the core 15. However, as the core print 16 is penetrated and supported in the core 15, the static pressure P is rigidly received by the core print 16 itself without influencing the imbalance of inner and outer pressure at part of the core print 16. Therefore, as the inner and outer pressures are perfectly balanced at the molding sand part of the core 15, the deformation of the core 15 can be prevented.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to improvements in cores for pressure casting.

(Prior art and its problems) Conventionally, as shown in FIG. is assembled, and a water jacket core 4 is assembled around the outer periphery of the bore core 3, and the water jacket core 4 has baseboards 4a on the outer peripheral surface,
It has been proposed that the mold 4a is fitted and supported by the upper mold 1 and the lower mold 2, respectively (see Japanese Patent Application Laid-Open No. 61-235039).

By the way, when pressure casting is performed using a two-legged mold, hydrostatic pressure P is generated in the cavity due to the molten metal, as shown in Figure 4. In the aerial core, in the baseboards 4a, 4a which are integrated into the core 4 and are fitted and supported by the upper mold 1 and lower mold 2, hydrostatic pressure I] acts as an internal pressure, but does not act as an external pressure. Since this does not work, the balance of internal and external pressures is lost at the baseboard portion, and this pressure imbalance causes the problem that the core 4 deforms into an oval shape with long sleeves in the y direction.

(Object of the Invention) The present invention was made to solve the above-mentioned conventional problems, and its object is to prevent deformation of a pressure casting core with a simple structure.

(Structure of the Invention) Therefore, the present invention is characterized in that the baseboard and the core portion following the baseboard are integrally molded by a rigid member, and the rigid portion is supported through the hollow core portion. It is.

(Operations and Effects of the Invention) According to the present invention, a baseboard integrally formed with a rigid member and a core portion following the baseboard are supported through the hollow core portion.

Therefore, in the structure of the hollow core for pressure casting according to the present invention, since the baseboard part where the internal and external pressures are unbalanced is formed of a rigid body, no deformation occurs, and the parts other than the baseboard are originally Since the internal and external pressures are balanced,
Deformation of the core can be effectively prevented with a simple structure.

In addition, the baseboard is a rigid member and does not require a coating layer to prevent molten metal from entering, unlike conventional baseboards that are integrated with a hollow core made of cast sand, improving dimensional accuracy.
It is also possible to effectively prevent cracking of the baseboard during mold clamping, which is likely to occur when the coating thickness of the coat stone is too large, and molten metal intrusion into the baseboard, which is likely to occur when the coating layer is too thin.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the mold IO used for casting engine cylinder blocks includes an upper mold 11 that mainly molds the upper half of the cylinder block, and a lower mold 12 that molds the lower half of the cylinder block. It is composed of an inner mold I3 for molding the inside.

A cavity 14 is formed between the upper mold 11 and the lower mold 12 and the inner mold I3.

A water jacket core I forming a water jacket of the cylinder block is disposed in the upper part of the cavity 14.
5 is assembled.

A through hole 15a in the left and right direction is provided at the lower part of the core 15.

. . , 15a are opened at appropriate locations, and a shaft-shaped rigid member 16 made of a rope is supported through the six through holes 15a.

The rigid member 16 forms part of the baseboard and the core 15, and forms an inlet and outlet for the water jacket of the cylinder block.

The core I5 is molded by distributing a thermosetting resin (resin) to casting sand such as silica sand or zirco sand, and heating and curing the resin.

In order to prevent the molten metal from entering the core 15, the core 15 is
The surface is coated with ceramic fine particles, flaky graphite, mica, etc. to a predetermined thickness (coating mold).

At this time, rigid members! 6 does not require a coat, so mask it.

A rigid member (baseboard) 16 that is supported through the core 15 has four parts 1 formed between the upper mold 11 and the lower mold 12.
Fitted and supported at 7.

After assembling the core 15 into the cavity 14 of each of the molds 11 to 13 and fitting and supporting the rigid member 16 into the recess 17 between the upper and lower molds II and 12, an aluminum alloy (for example, JIS ADC10) is assembled. is pressure cast, and after cooling, each of the molds 11-13 is divided, the casting is taken out, the rigid member 16 is pulled out from the casting, and the casting sand of the core 15 is discharged, and the cylinder block blank material is completed.

During the pressure casting, as shown in FIG. 3, hydrostatic pressure I] is generated by the molten metal in the cavity 14 and acts on the core 15, but the baseboard (rigid member 16) is not connected to the core as in the conventional case. Since it is supported through the core 15 rather than integrally, the baseboard 16
The unbalance of the internal and external pressures in the area is rigidly accepted by the skirting board 16 itself without affecting other parts, and the internal and external pressures are perfectly balanced in the casting sand area of the core 15. 15 is prevented from deforming.

Also, a rigid member! Since No. 6 does not require a coating layer, cracking of the baseboard during mold clamping and intrusion of molten metal into the baseboard are also prevented.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a casting mold according to the present invention, Fig. 2 is a perspective view of the core and rigid member (baseboard), Fig. 3 is an explanatory diagram showing the pressure applied to the core, and Fig. 4 is an explanatory diagram showing the pressure applied to a conventional core, and FIG. 5 is a sectional view of a conventional casting mold. 10... Mold, 11... Upper mold, 12... Lower mold, 1
3... Inner mold, 14... Cavity, 15... Water jacket core, 15a... Through hole, 16...
Rigid member.

Claims (1)

[Claims] (1) A core for pressure casting, characterized in that the baseboard and the core portion following the baseboard are integrally molded by a rigid member, and the rigid member is supported through the hollow core portion.