JPH07251254A - Die for forming cylinder block - Google Patents

Abstract

PURPOSE:To restrain the instrusion of molten metal between a die and a cylinder liner and to prevent the shift of the axis of the liner by forming a small diameter part for forming a molten metal pool part through a step part at the tip part of a bore pin formed to a little smaller diameter than the inner diameter of the cylinder liner to fit and hold the cylinder liner. CONSTITUTION:The cylinder liner L is fitted to the bore pin 6 of a movable die 5 and successively, the movable die 5 is joined to a fixing die 5 so as to insert the cylinder liner L into a cylinder forming part surrounded with slide cores 3, 3 at the right and the left sides. Thereafter, the molten metal of Al, etc., is poured into a cavity 11 formed among these dies and cores from a gate 4. Then, a part of the molten metal is flowed in the blind alley-like molten metal pool part 7 formed between the small diameter part 9 at the tip part of the bore pin 1 and the inner peripheral surface of the cylinder liner L. The molten metal is difficult to flow into a gap delta between the bore pin 6 and the cylinder liner L by a vortex developed at the pool part 7, and further, the tip part of the bore pin 6 is expanded to narrow the gap delta, and the intrusion of the molten metal is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding a cylinder block, and more particularly to a mold for molding a cylinder block while casting a cylinder liner.

[0002]

2. Description of the Related Art A cylinder liner is inserted into and held by a bore pin formed in one mold, and the cylinder liner is positioned in the cavity for molding the cylinder block of the other mold. In a mold device that is cast in a block, the outer diameter of the bore pin is formed to be slightly smaller than the inner diameter of the cylinder liner in order to facilitate the insertion of the cylinder liner and the opening of the mold after molding. There is.

For this reason, when the cylinder liner is inserted into the bore pin, a gap is created between the two, which is offset to one side, which causes molten metal to enter into this gap when pouring and to form a cylinder block. An axial misalignment occurs between the cylinder liner and the cylinder liner, and as a result, when machining is performed with the inner diameter of the cylinder liner as a reference, a reference deviation occurs.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its object is to:
To provide a mold for molding a new cylinder block, which can surely prevent the molten metal from entering between the mold and the cylinder liner while ensuring the insertability of the cylinder liner and the ease of opening the mold. It is in.

[0005]

That is, according to the present invention, as a mold for molding a cylinder block for achieving such a problem, one mold for molding the cylinder block is provided and a cylinder liner is inserted. A small diameter portion for forming a pool is formed at the tip of a bore pin formed to have a diameter slightly smaller than the inner diameter of the cylinder liner to hold and hold it, and the heat of the molten metal flowing into this portion causes the bore pin to flow. The tip portion of is expanded to eliminate the gap between the cylinder and the liner, thereby suppressing the intrusion of molten metal.

[0006]

Embodiments Now, the embodiments shown in the drawings will be described. FIG. 1 and FIG. 2 show a mold according to an embodiment of the present invention, which is shown in a state of pouring molten metal and a state of opening of the mold.

The fixed mold shown by reference numeral 1 in the drawing is composed of a male mold portion 2 forming the crank chamber inner surface of the cylinder block B, and left and right slide cores 3, 3 forming undercut portions of the outer surface. ing.

On the other hand, in the movable mold shown by reference numeral 5, a bore pin 6 having a diameter slightly smaller than the inner diameter of the cylinder liner L and a length substantially equal to the cylinder liner L is provided on the surface facing the fixed mold 1. A jacket-forming projection 10 is provided so as to surround this and protrudes annularly, and is configured to form a cavity 11 for forming the cylinder block B with the fixed die 1.

By the way, the above-mentioned bore pin 5 is a main part of the present invention, and when the cylinder liner L is attached to the outer periphery of the tip end thereof, it is between the inner peripheral surface and the outer peripheral surface of the tip end portion of the bore pin 5. In order to form an annular groove having a square cross section, a small-diameter portion 9 having a taper shape is formed at a tip end portion thereof via a step portion 8.
The portion surrounded by the inner peripheral surface of the cylinder liner L and the small diameter portion 9 is formed as a molten metal pool 7 into which molten metal flows during pouring.

In the embodiment constructed as described above, the cylinder liner L is now inserted into the bore pin 6 of the movable mold 5, and the cylinder liner L is surrounded by the left and right slide cores 3 and 3 to form a cylinder. When the movable mold 5 is joined to the fixed mold 1 so as to be fitted in the parts, and a molten metal such as an aluminum alloy is injected from the gate 4 into the cavity 11 formed between them, a part of this molten metal is , Flows into the hot water pool portion 7 formed between the small diameter portion 9 at the tip of the bore pin 6 and the inner peripheral surface of the cylinder liner L.
The vortex flow generated here makes it difficult for the molten metal to enter the gap δ between the bore pin 6 and the cylinder liner L, and at the same time, the tip portion of the bore pin 6 has a heat amount proportional to the amount of the molten metal flowing into the gap δ and the temperature at that time. Is expanded to narrow the gap δ with the cylinder liner L and prevent the molten metal from entering this portion.

When the cylinder block B is molded in this manner and then the mold is opened, as shown in FIG. 2, a surplus wall A corresponding to the pool 7 is formed on the inner surface of the tip of the cylinder liner L. After that, the cylinder block B is taken out from the fixed mold 1 and then this part is shaved off to complete the finished product.

[0012]

As described above, according to the present invention, a small diameter portion for forming a basin is provided at the tip of a bore pin provided on one mold for inserting and holding a cylinder liner through a step. Since it was formed, when joining the mold and pouring,
A swirl is generated in the molten metal that has flowed into the blind pool-shaped pool between the inner peripheral surface of the cylinder liner and the small diameter portion of the tip of the bore pin, making it difficult for the molten metal to enter between the bore pin and the cylinder liner, and By expanding the tip of the bore pin by heat, the gap between the bore pin and the cylinder liner can be narrowed, and axial misalignment of the cylinder liner caused by the molten metal entering this portion can be suppressed.

Moreover, by making the small diameter portion at the tip of the bore pin into a taper shape, the insertion of the cylinder liner can be facilitated and the mold opening can be smoothly performed, so that the cylinder block of this kind can be molded more efficiently. You can

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an apparatus according to an embodiment of the present invention, which is shown in a state at the time of pouring molten metal.

FIG. 2 is a sectional view of an apparatus according to an embodiment of the present invention shown in a mold open state.

[Explanation of symbols]

 1 Fixed mold 5 Movable mold 6 Bore pin 7 Hot water pool part 8 Step part 9 Small diameter part with taper B Cylinder block L Cylinder liner

Claims (2)

[Claims] 1. A tip end of a bore pin, which is provided in one of the molds for molding a cylinder block and is formed to have a diameter slightly smaller than the inner diameter of the cylinder liner for inserting and holding the cylinder liner, through a step portion. A mold for molding a cylinder block, characterized in that a small diameter portion for forming a basin is formed. 2. The mold for molding a cylinder block according to claim 1, wherein the small diameter portion is formed in a tapered shape with a tapered tip.