JPH08276251A - Insert structure in shell molding machine - Google Patents

Abstract

PURPOSE: To easily realize the mass production of two or more continuous half-split shell mold with excellent precision at a low cost by eliminating failures (differences generated in terms of the distance of movement, the precision, the timing, etc.), when a pin is advanced/retracted. CONSTITUTION: In a spiny insert 10 provided with a plurality of cylindrical half-split inserts 6A, 6B, 6C for making goods, and inserted into an insert inserting recessed part 7 formed in an undercut part R to be formed by the semi-circular surfaces of the adjacent inserts 6A, 6B, 6C for making goods in an advancing/retracting manner, the spiny insert is provided with the semi-circular surface 11A of the same curvature as that of the semi-circular surface of the inserts 6A, 6B, 6C for making goods, and a number of projections 12 are formed by achieving the electrical discharge machining on the semi-circular surface 11A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nesting structure in a shell molding machine for molding a shell mold for casting a cylindrical product such as a sleeve of a cylinder block.

[0002]

2. Description of the Related Art Generally, a cylinder block 80 is shown in FIG.
As shown in FIG. 0, a cylindrical sleeve 81 is manufactured by casting, and the sleeve 81 is placed in a cavity of a die casting mold.
A plurality of aluminum alloys are housed side by side, and a molten aluminum alloy is injected into the cavity by a die casting method.

In this case, a sleeve having a large number of projections on its surface is used in order to well bite the sleeve 81 into the aluminum alloy block body 82.
Such sleeves have been produced one by one in a cylindrical shape by casting using a sand mold made of green sand or hard sand.

[0004]

Since the sleeve having a large number of protrusions formed on the surface thereof is manufactured in a cylindrical shape by casting using a sand mold made of raw sand or slag hard sand, a storage core is required. It is very laborious, inefficient, inefficient,
There is a problem that it is not possible to mass-produce two or more sleeves.

In view of such a problem, as shown in FIG. 11, a large number of pin holes 41 are provided at opposite portions of a lower die cylinder having a semicircular cross section, that is, a kamaboko-shaped product insert 40. A pin 42 is inserted into each of these pin holes 41 so as to be retractable, and the pin 42 is connected at its base portion to a connecting member 43.
And the connecting member 43 is connected to the operating rod 44, and the operating rod 44 is moved in and out to operate the pin 42 so that the pin 42 has a lower mold and an upper mold. The pins 42 are projected into the space, and shell sand (silica sand plus a thermosetting polymer material) is blown into the space through a plurality of gates provided in the upper mold. , After the shell sand is hardened by this heating to form a shell mold, the upper mold is lifted, the upper mold is separated from the lower mold, and in the lower mold,
By operating the operating rod 44, the pin 42 is retracted to be released from the shell mold, and a large number of recessed portions for reverse copying of the pin 42 are formed in the undercut portion of the inner surface of the shell mold. Is proposed.

However, in order to project and retract a large number of the pins 42, a difference occurs in the distance of movement, accuracy, timing, etc., which hinders shell-type manufacture, and the pin holes 41 are not formed. The formation requires a small diameter and long hole, which causes a problem of high manufacturing cost.

The present invention solves the above-mentioned problems, and an object of the present invention is to have a problem when a pin is projected and retracted (a difference occurs in distance of movement, accuracy, timing, etc.). SUMMARY OF THE INVENTION It is an object of the present invention to provide a nesting structure in a shell-type molding apparatus that contributes to eliminating the problem and mass-producing a shell mold having a precision of two or more halves with high accuracy at low cost.

[0008]

In order to achieve the above object, a nesting structure in a shell-type molding apparatus according to the present invention has a structure in which a plurality of product halves each having a half-cylindrical shape are arranged, and adjacent product cavities have an arc shape. A nest that is insertably inserted into a nest insertion recess formed in an undercut portion formed by the surface and has an arcuate surface having the same curvature as the arcuate surface of the product nest, and a large number of arcuate surfaces. It is characterized in that it is provided with a protrusion.

A plurality of protrusions may be formed on the arcuate surface by subjecting the insert material to electric discharge machining.

[0010]

With such a structure, by forming a large number of protrusions in the nest in advance, there is a problem that a pin is projected and retracted (a difference occurs in the distance of movement, accuracy, timing, etc.). Eliminate the problem, and easily mass-produce a half-precision shell mold with a precision of 2 or more. In addition, manufacturing cost is reduced by forming a large number of protrusions on the arc-shaped surface by electric discharge machining.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. 1 is a plan view of a nesting structure in a shell-type molding apparatus according to the present invention, FIG. 2 is a side view of the nesting structure,
3 is a cross-sectional view taken along the line AA of FIG. 1, FIG. 4 is a cross-sectional view of a state in which a rod is mounted in a nesting structure, FIG. 5 is an explanatory diagram of electric discharge machining in the manufacturing process of the spiny nest, and FIG. 6 is a spiny nest. 3 is a cross-sectional view of the nest material of FIG.

The spiny nest 10 which is a nest is shown in FIG.
As shown in FIG. 3, it has a nesting body 11, and the surface of this nesting body 11 is an arcuate surface 11A having the same curvature as the arcuate surface of the product nest described later, and there are many arcuate surfaces 11A. Projections 12 are formed.

The spiny insert 10 is manufactured by subjecting the insert material 10-1 to electric discharge machining. That is, as shown in FIG.
Block-shaped nesting material 10 in which 1-1 is formed in an arc shape
-1 is the workpiece W, and the machining electrode 30 shown in FIG. 5 is used. The machining electrode 30 has a surface 30A which is a concave arcuate surface in which the machining surface (the arcuate surface 11-1) S of the workpiece W is reversed, and a large number of arcuate surfaces 30A are formed on the arcuate surface 30A. The unevenness 31 is formed.

Then, the surface 30A of the machining electrode 30 is opposed to the machining surface S of the workpiece W (the gap length between the machining electrode 30 and the workpiece W facing each other is very narrow, and a kerosene is present in the gap). An insulating liquid such as water or water.), While applying an impulse voltage of about 60 to 300 V between the machining electrode 30 and the workpiece W, intermittent spark discharge is performed,
Using the abnormal consumption phenomenon that occurs at that time, the workpiece W
In the processing S, the unevenness having the reverse shape of the unevenness 31 of the processing electrode 30, that is, a large number of protrusions 12 are formed.

The spiny nest 1 manufactured in this way
Two rods 13 are attached to 0. Then, as shown in FIG. 7, the spliner nest 10 has the spliner nest insertion recess 7 of the product nests 6A, 6B, 6C of the lower mold 1.
Is inserted so that it can appear and disappear.

That is, the product nests 6A, 6B, 6
C is a cylindrical body having a semicircular cross section, that is, a semi-cylindrical shape, and is an undercut portion R of the product inserts 6A, 6B, 6C.
A rectangular spiny nesting insertion concave portion 7 is formed in a plan view in the opposing portions forming the. Further, the product inserts 6A, 6B, 6C are formed with rod insertion holes 8 reaching the spiny insert insertion recesses 7. These rod insertion holes 8 are pin insertion holes provided in the lower hot plate body 5. It communicates with the hole 9.

Then, the spiny nesting insertion recess 7 is formed.
The spiny nest 10 is inserted into the spine nest insertion recess 7 by inserting the rod 13 into the rod insertion hole 8.

The pull-out pin 14 has the pin insertion hole 9 described above.
The pull-out pin 14 is connected to the rod 13 of the spiny insert 10. The pull-out pin 14 is connected to a retracting operation means (not shown) for retracting the spiny nest 10.

Further, the upper mold 2 is provided with an upper mold body 15, and the upper mold body 15 has a cavity 17 formed on the mold matching surface 16 side, and the cavity 17 is formed in the lower mold 1. The plurality of concave portions 18 facing the product nests 6A, 6B, 6C of FIG.
A gate (not shown) that communicates with each recess 18 is provided in the. The upper mold 2 is moved up and down by an elevating operation mechanism (not shown) which is an upper mold moving means.

Then, in the lower die 2, by operating the projecting / retracting operation means to move the pull-out pin 14 and push the spiny insert 10, the arcuate surface 11 of the product insert 6A, 6B, A large number of protrusions 12 on this arcuate surface 11 are projected in conformity with the surface of 6C.

Next, the upper die 2 is lowered by the operation of the elevating and lowering mechanism, and the die matching surface 16 of the upper die body 15 is moved.
To the mating surface of the lower mold 1 and insert the product nests 6A, 6B, 6C of the lower mold 1 into the concave portions 18 of the cavity 17, and between them, a space H in the shape of a sand mold to be molded.
Is formed.

Next, shell sand (silica sand plus a thermosetting polymer material) is blown into the space H from a plurality of gates provided in the upper mold body 15.

Next, the heaters 19A and 19B provided on the upper and lower molds 1 and 2 are energized to heat the upper mold body and the product inserts 6A, 6B and 6C to about 350 ° C. This heating cures the shell sand and molds the shell mold 70.

Next, the energization of the heaters 19A and 19B is stopped, and the upper die 2 is operated by the operation of the elevating mechanism.
Is lifted to separate the upper mold 2 from the lower mold 1. In this state, the shell mold 70 is attached to the product inserts 6A, 6B, 6C side of the lower mold 1.

Next, in the lower die 2, by operating the projecting / retracting actuating means, the pull-out pin 14 is retracted to simultaneously retract the spiny nest 10, and the arcuate surface 11 of the spine nest 10 is moved to the front, middle and The projections 12 provided on the arcuate surface 11 are released from the shell mold 70 by drawing in from the surface of the product nests 6A, 6B, 6C on the rear side.

Next, an eject pin (not shown) rises to push up the shell mold 70 and release the shell mold 70. This shell mold 70 has a half-divided shape, and the undercut portion on the inner surface of the shell mold 10 has a spiny insert 10.
A large number of recessed portions of the reverse projection of the large number of protrusions 12 are formed.

Moving to the next step, as shown in FIG. 8, four bore cores 71 are set, and the mating surface portions 70A of the shell mold 70 having a half-divided shape are bonded together with an adhesive to form a shell mold mold. Created.

After this shell mold mold is transported to the casting site, aluminum alloy is poured in the casting process to cast four sleeves shown in FIG. A number of protrusions 12 'are formed on the undercut sleeve R'of this sleeve. Then, this sleeve is cast into an aluminum alloy by a die casting method to form a cylinder block.

[0029]

As described above in detail, the nesting structure in the shell-type molding apparatus according to the present invention has a plurality of cylindrical product inserts arranged in a line, and an under surface formed by arc-shaped surfaces of adjacent product inserts. A nest that is inserted into and retractable from a nest insertion recess formed in the cut portion and has an arcuate surface having the same curvature as the arcuate surface of the product nest, and a large number of protrusions are provided on this arcuate surface. By doing so, it is possible to eliminate a defect point (a difference occurs in terms of movement distance, accuracy, timing, etc.) when the pin is projected and retracted. The shell type can be easily mass-produced.

Further, the manufacturing cost can be reduced by forming a large number of projections on the arcuate surface by electric discharge machining.

[Brief description of drawings]

FIG. 1 is a plan view of a nesting structure in a shell-type molding apparatus according to the present invention.

FIG. 2 is a side view of the nesting structure.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a cross-sectional view of a state in which a rod is attached to the nest structure.

FIG. 5 is an explanatory diagram of electric discharge machining in a manufacturing process of a spiny nest.

FIG. 6 is a cross-sectional view of a nesting material for spiny nesting.

FIG. 7 is a cross-sectional view of a main part of the shell-type molding apparatus.

FIG. 8 is a plan view of a shell mold including a bore core and a half-shell type mold.

FIG. 9 is a perspective view of a quadruple sleeve.

FIG. 10 is a perspective view of a cylinder block using a conventional sleeve.

FIG. 11 is an explanatory diagram of a protruding and retracting pin structure for forming a large number of recessed portions for reverse copying of the pin in the undercut portion of the inner surface of the shell type.

[Explanation of symbols]

 1 Lower Die 2 Upper Die 6A, 6B, 6C Product Nesting 7 Nesting Insertion Recess 10 Spyney Nesting (Nesting) 11A Circular Surface 12 Protrusion

Claims (2)

[Claims] 1. A nest insertable in and out of a nest insertion recess formed in an undercut portion formed by arc-shaped surfaces of adjacent product nests, wherein a plurality of product nests each having a half-cylindrical shape are arranged. A nesting structure in a shell-type molding apparatus, which has an arcuate surface having the same curvature as the arcuate surface of the product insert, and a large number of protrusions are provided on the arcuate surface. 2. A nesting structure in a shell-type molding apparatus according to claim 1, wherein a large number of protrusions are formed on the arcuate surface by subjecting a nesting material to electric discharge machining.