JPH1029038A - Manufacture of core and manufacturing device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always stably manufacture a core having high compressive strength and good collapsibility by packing self-hardening small grain solid bodies into the cavity in a core mold, heating the core mold and evacuating the inner part of space part through evacuation from plurality venting holes arranged in the space part. SOLUTION: The iron-made core mold 1 arranged with the number of venting holes 3 having the total area corresponding to about 20% of the surface area of the hollow part 2 at equal intervals in the inner surface of the hollow part 2, is laid on the vibrating table 5a of a three-dimensional vibrating molding machine 5. The solid bodies 4 made of the self-hardening molding sand is packed into the inner part of hollow part 2 while operating the three-dimensional vibrating molding machine 5 from a core print part 6. The core mold 1 completed with the filling-up is laid on core mold supporting rods 8 in a heating box so that the heat is uniformly applied to the core mold 1. The core mold is heated for one hour at such temp. of 100 deg.C that binder contained in the solid body 4 is not decomposed with the heat. After heating, the core mold 1 is taken out and laid on core mold supporting rods 10 in a vacuum box 9, and a valve 12a is opened and the inner part of the vacuum box 9 is evacuated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a core and an apparatus for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in a method of manufacturing a core, a suction flow box 33 for hardening a core having a suction port 32 provided on a vibration table of a three-dimensional vibration molding machine 31 shown in FIG. A core model 34 provided with a suction air flow means is installed in the vessel, and self-hardening molding sand 35 kneaded in another place is charged from an input port 36 provided in the core model 34, and the three-dimensional vibration molding machine 31 Is operated to fill the core model 34. The three-dimensional vibration molding machine 31 is stopped, and the self-hardening molding sand 35 is charged again to operate the three-dimensional vibration molding machine 31. Immediately after the charging and the charging of the sand are repeated and the filling is completed as described above, the suction flow device 37 is operated to suction the flow in the core model 34 through the suction pipe 38 and the suction flow box 33. The moisture of the self-hardening foundry sand 35 and the binder dehydrate and remove the moisture generated during the chemical reaction to promote hardening. After filling the product cavity 40 of the core box 39 shown in FIG. 5 with the kneading sand 41 containing the water-soluble glue, the column 42 forming the C shape is formed.
The cylinder 45 is operated by placing the clamp head 46 on a surface plate 44 provided on the upper surface of an elevating table 43 and adjusting the vertical position of the clamp head 46 via a support rod 47 pointing up and down in accordance with the extension of the cylinder 45. Then, the upper and lower ends of the core box 39 are clamped from above and below so as to come into contact with the air holes 48a and 48b provided in the surface plate 44 and the clamp head 46. Open the on-off valve 49 and open the compressed air storage tank 50
The heated and compressed air stored in the vent 4
Exhaust holes 5 provided at positions where compressed air blown from above and below is blown from the upper and lower ends of the product cavity 40 of the core box 39 to flow through the kneading sand and merged from above and below.
Discharge from 1. The air heated and compressed to a predetermined temperature is blown through the kneading sand through at least two or more openings facing each other, and discharged from the vicinity of the merging position, whereby the water in the kneading sand evaporates quickly. Dry and harden in a short time. (For example, see Japanese Patent Application Laid-Open No. 5-23759)
4 and JP-A-56-151138)

[0003]

Among the methods described in the conventional core manufacturing method, in the former method, the method of sucking and flowing air inside the model is such that the air is linear between the suction port 32 and the charging port 36. There is no air flow at the corners due to air flow. In addition, when the distance between the suction port 32 and the charging port 36 is long, since the area between the sand particles is small, the air does not easily pass through, and the flowing air stops on the way. Furthermore, when there are multiple inlets, the air flows between the inlet closest to the suction port and the suction air does not occur much between the other inlets. Is difficult to remove by dehydration, and the uncured portion is easily damaged. In the latter, as in the former, the ventilation holes 48
The flow of air is linear between the exhaust holes 51a and 48b and the heated compressed air is not transmitted at the corners. When the distance between the vent holes 48a and 48b and the exhaust hole 51 is long, the air is difficult to pass through because the area between the sand particles is small, and the compressed air is not transmitted halfway. Furthermore, compressed air must be supplied from at least two outer surfaces facing each other, and it is almost impossible to manufacture a core with a complicated shape. It is difficult to dry and cure, and the uncured portion is easily damaged.

The present invention has been made in view of such conventional problems, and an object of the present invention is to uniformly remove water in a solid body of self-hardening small particles in a short time by evacuation. And hardened to form a core. Also,
In a manufacturing apparatus, by providing a vacuum chamber and a heating element in a core mold, core molding can be performed at the same place without moving the core mold.

[0005]

In order to achieve the above object, a method of manufacturing a core according to the present invention is directed to a method of filling a solid body of small particles of self-hardening into a core-shaped cavity while vibrating. The mold is heated, and the inside of the cavity is evacuated by vacuuming through a plurality of ventilation holes provided in the cavity, and water is removed and cured to produce a core. Also, it is manufactured by using a water-soluble adhesive as a binder as self-hardening. Further, in the manufacturing apparatus, the core mold is divided into a plurality of parts, the inside of which is communicated with the vacuum chamber and the cavity through the ventilation hole, and a heating element is provided in the vacuum chamber to heat the core mold, and moisture is externally provided. Is provided on the vibration table of the vibration molding machine,
The outlet is connected to a vacuum pump to evacuate the cavity communicated with the vacuum chamber and the vent.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. The core is manufactured by using iron as a material and providing ventilation holes 3 having a hole diameter of about 0.5 mm on the inner surface of the cavity 2 at regular intervals by the number of holes corresponding to about 20% of the surface area of the cavity 2. Core type 1
It is placed on the vibration table 5a of the three-dimensional vibration molding machine 5. The cavity 2 is formed by operating the three-dimensional vibration molding machine 5 from the baseboard 6 in which the solid body 4 made of self-hardening molding sand is opened out of the core mold 1.
Fill inside. (Refer to FIG. 1a.) The filled core 1 is placed on a heating box core supporting rod 8 provided inside the heating box 7 so that heat is evenly applied to the core 1. Heating is performed for 1 hour at a temperature of 100 ° such that the binder (furan resin) contained in the solid body 4 of the self-hardening molding sand is not decomposed by heat. (Refer to FIG. 1b.) Immediately after heating, the core 1 is placed on the vacuum box core support rod 10 in the vacuum box 9 and the vacuum pump 11
To open the opening / closing valve 12a and open the cavity 2 of the core 1
The inside of the vacuum box 9 is evacuated so as to make a vacuum. 1
After a lapse of 5 to 25 minutes, the open / close valve 12a is closed, the vacuum pump 11 is stopped, another open / close valve 12b is opened, and outside air is introduced into the vacuum box 9. (See FIG. 1 c) Take out the core mold 1 from the vacuum box 9. The core mold 1 is opened in the left-right direction, and the core 13 formed by curing is taken out.
(See Fig. 1d)

Next, as another embodiment, a self-hardening molding sand obtained by kneading a water-soluble adhesive composed of a vinyl acetate resin and a molding material of molding sand as a main component of a binder is used to wash the molded product with water. The core can be more easily taken out.

As an embodiment of the core manufacturing apparatus 14 shown in FIG. 2, the core mold 15 is divided into an upper core mold 15a and a lower core mold 15b, and a vacuum chamber 16 and a cavity 17 are formed therein. The vacuum chamber 16 is provided with a heating element 19 for evaporating the moisture of the binder and a discharge port 20 for discharging the water to the outside. The vibration table 21 a of the three-dimensional vibration molding machine 21 is provided in the vacuum chamber 16. I put it. The heating element 19 is connected to a temperature control device 22 by a power cord 23. The discharge port 20 is connected to a vacuum pump 26 via a pressure-resistant hose 24 and a suction control unit 25. The suction control section 25 is arranged so that the opening / closing valve 25a is opened and the vacuum chamber 16 can be evacuated by closing the opening / closing valve 25b. Sealing device 27
Can be fixed to the upper core mold 15a and the lower core mold 15b with bolts 28a and 28b in order to seal the cavity portion 17. Core manufacturing apparatus 1 configured as above
The solid body 29 made of self-hardening molding sand is filled from the opening 17a of the cavity 17 of the fourth part 17 while the three-dimensional vibration molding machine 21 is operated. The sealing device 27 is fixed to the upper core mold 15a and the lower core mold 15b with bolts 28a and 28b. The power of the temperature control device 22 is turned on, the heating element 19 is operated, and the core mold 15 is heated. Open / close valve 25 immediately after heating
a is opened, the open / close valve 25b is closed, and the vacuum pump 26 is operated to evacuate the cavity 17. FIG. 3 shows a state in which the core 30 is taken out. The hardened core 30 stops the vacuum pump 26, opens the on-off valve 25b, and allows outside air to enter the vacuum chamber 16. Remove the closure 27. Upper core type 1
5a, the lower core mold 15b is vertically opened and taken out.

Furthermore, the core produced by the present invention has a higher compressive strength than the core produced by the carbon dioxide method, which is said to be strong in the mold molding method (the carbon dioxide method). The value of the compressive strength of the core manufactured in 13.4 is 13.4.
In the experiment, a value of compressive strength of 67 kg / cm ² or more was obtained with respect to 4 kg / cm ^2. ) It can be used as a core for casting and resin molding. In particular, when a water-soluble adhesive is used, it can be easily decomposed by washing with water and has good disintegration properties. The core material may be a material having air permeability, for example, ceramics.

[0010]

According to the present invention, a solid body of small particles of self-hardening is filled in a core-shaped cavity, the core is heated, and the core is evacuated through a plurality of ventilation holes provided in the cavity. By evacuating the interior of the cavity, moisture in the solid body of small particles of self-hardening can be uniformly removed in a short time and cured. In addition, a stable core can be produced without being affected by the temperature and humidity of the outside air, and the compressive strength is high and the disintegration is good. In the manufacturing equipment, a vacuum chamber and a heating element are provided in the core mold, the vacuum chamber and the vacuum pump are connected, and the heating element and the temperature control device are connected to heat the core in the same place without moving the core mold. In addition, the core can be formed by vacuum evacuation, which can prevent an accidental accident during transportation, and can reduce the size and space of the manufacturing equipment and improve workability.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a manufacturing process diagram in a core manufacturing method of the present invention.

FIG. 2 is an apparatus for manufacturing a core according to the present invention.

FIG. 3 is a drawing showing a state in which a core of the present invention is taken out.

FIG. 4 is a sectional view showing a conventional core manufacturing method.

FIG. 5 is a sectional view showing a conventional core manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core type 2 Cavity part 3 Vent hole 4 Self-hardening solid body of small particles 7 Heating box 9 Vacuum box 11 Vacuum pump 13 Core

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[Procedure amendment]

[Submission date] April 24, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

FIG. 4

FIG. 3

FIG. 5

Claims (3)

[Claims] A solid body of small particles of self-hardening is filled in a core-shaped cavity while being vibrated, the core is heated, and the cavity is evacuated from a plurality of ventilation holes provided in the cavity. A method for manufacturing a core, wherein the inside of the core is evacuated, moisture is removed, and the core is formed by curing. 2. The method for producing a core according to claim 1, wherein a water-soluble adhesive is used as the binder as self-hardening. 3. The core mold is divided into a plurality of parts, the inside of which is communicated with a vacuum chamber and a cavity through an air hole, a heating element is provided in the vacuum chamber to heat the core mold, and a water content is externally provided. Is provided on the vibration table of the vibration molding machine, and the discharge port is connected to a vacuum pump to evacuate the cavity communicated with the vacuum chamber and the vent. An apparatus for manufacturing a core.