JPH0536147B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for molding a green sand core, and more specifically, to a method for molding a green sand core having a shape in which the central part and the peripheral part have different thicknesses. METHODS AND APPARATUS.

(Conventional technology) Cores are manufactured using shell molding, cold boxing, CO ₂ molding, etc. mainly for reasons of strength and dimensional accuracy.
However, cores made by this method are expensive and have different properties from the main mold made of green sand, so they require sand recycling treatment after pouring. There is a problem above. For this reason, various methods of molding cores using the same green sand as the main mold have recently been attempted, and cores of relatively simple shapes that can be used for practical purposes have been molded. There is.

However, it has been difficult to mold a complex-shaped core with uniform strength and good dimensional accuracy.

(Object of the Invention) The present invention has been made in view of the above circumstances, and provides a green sand core with a complex shape that has uniform strength and good dimensional accuracy, especially in the center and peripheral parts. It is an object of the present invention to provide a method and an apparatus for molding green sand cores having shapes with different thicknesses.

(Example) Below, the configuration of a device adapted to carry out the present invention will be explained with reference to FIG.
A table 3 is fixed thereto. An upwardly directed extrusion cylinder 4 is erected in the recess 2 of the table 3, and a connecting plate 5 is fixed to the tip of the piston rod of the extrusion cylinder 4. A lower mold 7 is mounted on the table 3, which has a recess 6 on its upper surface that corresponds to the shape of the lower half of the desired core, and a slight recess on its lower surface. The recess 6 is adapted to define a preform cavity or a cavity corresponding to a desired core by fitting a blow mold or a compression mold to be described later.

An extrusion plate 9 with a plurality of extrusion pins 8 implanted in the upper surface of the lower die 7 is provided with the connection plate 9.
The push-out pin 8 is provided so as to be able to pass through the lower die 7 and retract from the bottom surface of the recess 6.

A blow tank 10 is disposed above the table 3 at an appropriate interval, and on the lower surface of the blow tank 10, a dimension in the vertical direction is larger than the shape of the upper half of the desired core. A blow mold 12 having a recess 11 formed therein is fixed to the recess 6 of the lower mold 7 so as to have an outer shape that can be slidably fitted therein. Furthermore, a sand blowing hole 13 is bored through the bottom plate of the blow tank 10 and the blowing die 12.

Note that reference numeral 14 is an exhaust hole having one end opened in the peripheral portion of the lower surface of the blowing mold 12 and the other end opened in the side wall of the blowing mold 12, into which a vent plug 15 is fitted.

A stopper 16 is fixed to the outer periphery of the lower surface of the blow tank 10 so as to surround the blow mold 12, and the lower surface of the stopper 16 can come into contact with the outer periphery of the upper surface of the lower mold 7.

Furthermore, a roller conveyor 17 for transporting the green sand main mold is arranged at an appropriate interval outside the lower mold 7, and a surface plate 1 is mounted on the roller conveyor 17.
A green sand main mold 20 with a frame 19 is placed through the mold 8.

Further, an upward cylinder 21 is disposed below the roller conveyor 17, and a push-up plate 22 is fixed to the tip of the piston rod.

Furthermore, a position between the lower mold 7 and the blowing mold 12;
A hollow roller conveyor 23 is disposed above the push-up plate 22 of the roller conveyor 17, and a frame-shaped traveling frame 24 is placed on the hollow roller conveyor 23. The running frame 24 has a flange 25 on its upper outer circumference.
A compression mold 26 is detachably suspended via the flange 25, and a recess 27 corresponding to the shape of the upper half of the desired core is formed on the lower surface of the compression mold 26. Recessed portion 6 of the lower mold 7
It has an external shape that can be inserted into.

A recess 28 is formed on the upper surface of the compression mold 26, and an extrusion plate 30 with a plurality of extrusion pins 29 embedded in the lower surface thereof is disposed within the recess 28. , the compression mold 26
It is provided so as to be able to penetrate through the bottom surface of the recessed portion 27 and retract from it.

Further, a coil spring 31 is installed between the bottom surface of the recess 28 in the push-out pin 29 and the push-out plate 30, and the extension force of the coil spring 31 pushes the push-out plate 30 upward. It is made to work like this.

Further, a stopper 33 for restricting the upward movement of the extrusion plate 30 is disposed at the upper position of the recess 28, and when the extrusion plate 30 is in contact with the extrusion plate 30, the lower end of the extrusion pin 29 is flush with the lower surface of the compression mold 26. The position has been adjusted so that it is level. Further, a piston rod 35 of a horizontal cylinder 34 provided at the end of the roller conveyor 23 is connected to the traveling frame 24, so that the compression mold 26 is reciprocated on the roller conveyor 23 together with the traveling frame 24. It's getting old.

Further, a downward cylinder 36 is located above the roller conveyor 23 opposite to the upward cylinder 21.
A push-down plate 38 corresponding to the push-out plate 30 is fixed to the lower end of the piston rod 37.

With this structure, the upward cylinder 1 is extended in the state shown in FIG. At the same time, the upper surface of the lower mold comes into contact with the stopper 16 and the lifting is stopped. As a result, the recess 6 of the lower mold 7 and the recess 11 of the blowing mold 12 define a preform cavity whose upper half is enlarged upward compared to the desired shape of the core.

Next, compressed air is supplied into the blow tank 10,
The green sand contained therein is blown into the preform cavity through the blow hole 13 to form a preform. At this time, the compressed air blown in together with the green sand is discharged from the vent plug 15 to the atmosphere through the exhaust hole 14.

Next, the upward cylinder 1 is retracted, and the lower mold 7 is lowered with the preform held in the recess 6 of the lower mold 7 to separate it from the blowing mold 12.

Next, the horizontal cylinder 34 is extended to move the compression mold 26 together with the traveling frame 24 to a position between the lower mold 6 and the blowing mold 12, and then the upward cylinder 1 is extended again to raise the lower mold 7. let

Due to this operation, the upper surface of the preform held on the lower mold 7 comes into contact with the lower surface of the compression mold 26, and the lower mold 7 continues to rise, and the compression mold 26 is separated from the traveling frame 24. The upper surface of the compression mold 26 touches the blowing mold 12 as it continues to rise.
When the compression mold 26 comes into contact with the lower surface of the lower mold 7, its ascent is stopped and only the lower mold 7 continues to rise.
The upper surface of the lower mold 7 comes into contact with the step on the lower surface of the compression mold 26, and its rise is stopped, and the preform is compressed into the desired core. It is compressed to the shape of .

Next, while the extrusion cylinder 4 is extended, the upward cylinder 1 is retracted. The molded core is separated from the lower mold 7 while being held in the compression mold 26 because the lower mold 7 is lowered while being pushed upward by the extrusion pin 8. The compression mold 26 holding the core begins to descend together with the lower mold 7 while being supported by the extrusion pins 8, and the flange 25 of the compression mold 26 comes into contact with the traveling frame 24, stopping its descent and separating it from the lower mold 7. will be held.

Next, the horizontal cylinder 34 is retracted to move the compression mold 26 together with the traveling frame 24 to a position directly above the main mold 20 of sand with the frame 19 on the roller conveyor 17, and the upward cylinder 21 is extended to move the push-up plate. The green sand main mold 20 is pushed up via the green sand main mold 22 and the surface plate 18, and the core held in the compression mold 26 is relatively inserted into the core setting position of the green sand main mold 20, and its ascent is stopped. .

Next, the downward cylinder 36 is operated to extend, and the push-out pin 29 is pushed down against the coil spring 31 via the push-down plate 38 and the push-out plate 30, while the upward cylinder 21 is operated to retract. The green sand main mold 20 is pushed out from the compression mold 26 and held on the green sand main mold 20 side, and the green sand main mold 20 is lowered together with the surface plate 18 and returned onto the roller conveyor 17. 1 main mold 20
Move the next green sand main mold 20 to the push-up plate 22.
Position it directly above.

Meanwhile, at the position of the lower mold 7, a preformed body is molded using the blowing mold 12 in the same manner as described above.

By repeating the above operations, the molding of the green sand core and the setting of the core into the green sand main mold 20 are performed in sequence.

In the above embodiment, when setting the core held in the compression mold 26 into the green sand main mold 20,
Although the green sand main mold 20 is elevated, the roller conveyor 23 is divided into divided roller conveyors 23' as shown in FIG. By connecting the running frame 24 and the horizontal cylinder 34 with a vertically slidable rod 41, the green sand main mold 20 can be moved up and down except for the upward cylinder 21 and the push-up plate 22. It is possible to set the core by lowering the compression mold 26 together with the dividing roller conveyor 23' without raising it.

(Effects of the Invention) As described above, the present invention molds a preformed body whose upper half is enlarged upwardly compared to the shape of a desired core, and compression molds this preformed body into the shape of the desired core. By doing so, it is possible to mold a core in which the strength of the central thick part and the peripheral thin part are almost uniform.

Furthermore, the green sand in the central thick part of the preform is
Since it is tightly tightened by the compression mold, the transferability of this part is improved, and a core with better dimensional accuracy can be obtained. Furthermore, by using a device that is associated with a roller conveyor for transporting green sand main molds, various effects such as being able to release the shaped cores from the compression molds and set them in the main molds at the same time can be obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing another embodiment of a mechanical part for setting a core in a main mold.

Claims (1)

[Scope of Claims] 1. A lower mold having a recessed portion corresponding to the shape of the lower half of the desired core on its upper surface, and a recessed portion having a vertical dimension larger than the shape of the desired upper half of the core on its lower surface. a step of aligning the formed blowing mold with their concave portions facing each other, thereby defining a preforming cavity;
a step of blowing and filling green sand together with compressed air into the preform cavity to form a preform; A step of separating from the mold, and a compression mold having a recess formed on the lower surface corresponding to the shape of the upper half of the desired core is carried above the lower mold, and the compression mold and the lower mold are placed so that their recesses face each other. a step of compression-molding the preform into the shape of a desired core by combining the molds together, and a step of separating the lower mold from the compression mold while holding the compression-molded core in the recess of the compression mold. A method for shaping a green sand core, comprising the steps of: carrying out the core held in the compression mold together with the compression mold from above the lower mold, and then separating the core from the recess of the compression mold. 2. A lower mold 7 having a recess 6 corresponding to the shape of the lower half of the desired core on its upper surface is disposed so as to be movable up and down, and a blow tank 10 is disposed above the lower mold 7 at an appropriate interval. At the lower end of the blow tank 10, a recess 11 is formed on the lower surface, the dimensions of which are larger in the vertical direction than the shape of the upper half of the desired core, and which can be slidably fitted into the recess 6 of the lower mold 7. A blowing mold 12 having an outer shape is fixed, and a sand blowing hole 1 is formed by penetrating the blowing mold 12 and the bottom plate of the blow tank 10.
3, and a hollow roller conveyor is disposed outward from a position between the lower die 7 and the blowing die 12, and a hollow roller conveyor is provided with a hollow roller conveyor on the lower surface. A compression mold 26, which has a recess 27 corresponding to the shape of the half part and an outer shape that can be fitted into the recess of the lower mold 7, is mounted so as to be movable via the traveling frame 24, and the compression mold 26 is equipped with a mold. A green sand core molding device characterized in that a core extrusion mechanism 29, 30, 31, 33 is attached. 3. A lower mold 7 having a recess 6 corresponding to the shape of the desired lower half of the core on its upper surface is disposed so as to be movable up and down, and a blow tank 10 is disposed above the lower mold 7 at an appropriate interval. At the lower end of the blow tank 10, a recess 11 is formed on the lower surface, the vertical dimension of which is larger than the shape of the upper half of the desired core, and
A blowing mold 12 having an external shape that can be slidably fitted into the recess 6 of the lower mold 7 is fixed, and a sand blowing hole 13 is bored through the blowing mold 12 and the bottom plate of the blow tank 10. A roller conveyor 17 for transporting the green sand main mold is disposed outside the lower mold 7, and a roller conveyor 17 for transporting the green sand main mold is installed from a position between the lower mold 7 and the blowing mold 12. A hollow roller conveyor is disposed over the upper position, and a recess 27 corresponding to the shape of the upper half of the desired core is formed on the lower surface of the hollow roller conveyor, and the recess 27 is fitted into the recess of the lower mold 7. A compression mold 26 having a possible external shape is mounted so as to be movable via the traveling frame 24, and the compression mold 26
6 is a molding core extrusion mechanism 29, 30, 31, 3
A green sand core molding device characterized in that 3 is attached.