JPH02299743A - Method for molding green sand core - Google Patents

Abstract

PURPOSE:To integrate divided molding cores and to mold the high strength core by primarily compressing divided core boxes packed with green sand and further, secondarily compressing with a bar. CONSTITUTION:The green sand S is charged into a banking flask 8 added to joint faces of the divided cores 1a, 1b, and is pressurized and primary compressed to the cavity faces 3a, 3b in the divided cores and the upper faces of green sands S coincide with the joint faces. After joining the plural pieces of the divided core boxes 1a, 1b, the pressurization is applied from center of green sand S toward the outer side with the reverse conical bar member 17. By this method, the green sands S molded under dividing are integrated and the secondary compression-hardening can be applied.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method suitable for molding cores of complex shapes using green sand.

(Prior art and its problems) The conventional method for molding green sand cores involves inserting a rod member shaped like an inverted cone into green sand filled in a core box to compress the green sand. A method of hardening is used. (Japanese Patent Publication No. 64-9101) However, when molding a core with a complicated mold shape using this method, there is a drawback that the green sand cannot be sufficiently filled into the details of the cavity. The core molding method has been limited to molding a core with a simple shape.

(Objective) The present invention was made in view of the above problems, and an object of the present invention is to provide a method by which a core having a complicated shape can be molded using green sand.

(Means for Solving the Problem) The present invention introduces green sand into the filling frame additional cavity of each split core box in which a filling frame is added to the molding surface, and the introduced green sand is Pressure is applied toward the cavity surface of the split core box to cause the green sand to undergo primary compression hardening, and the upper surface of the green sand is made to match the molding surface of the split core box, and the primary compression hardened green sand is After mold-matching multiple split core boxes holding sand, a rod member with an approximately inverted cone-shaped tip is inserted into the green sand to apply pressure to the green sand from the inside to the outside. The method is characterized in that the green sand that has been divided and molded is integrated and at the same time subjected to secondary compression hardening.

(Function) By adopting the solution described above, the present invention allows green sand to be compressed toward the surface of the cavity after it is sufficiently filled into the details of the cavity of each split core box. Pressure is applied from the inside outward to the primary compression hardened green sand that has been molded.
As a result, the green sand that has been divided and molded is integrated and at the same time is subjected to secondary compression hardening to form a core.

(Example) Embodiments of the present invention will be described in detail below based on the drawings.

In Figure 4, a split core box (l) that can be divided into left and right
a) (lb) is molded and has a closed bottom wall part (2a
) (2b), and a complex cavity surface (
3a) and (3b), each defining a cavity having an opening (4) at the upper end. In the figure, (5a) and (5b) are core extrusion pins, and (6a) and (6b) are extrusion plates.

The thus configured split core box (1a) is turned sideways as shown in FIG. (2a), and furthermore, a filling frame (8) is installed on the top surface of the planar rectangular shape formed by the mold matching surface of the horizontally split core box (la) and the plate member (7). Place it.

In addition, a blow head composed of a blow tank (9) and a blow plate (10) is crimped onto the upper part of the filling frame (8), and the blow tank (9) is operated to produce green sand (S).
from the blowing port (11) to the filling frame (8) and the split core box (1a).
) and the plate member (7), and the state shown in FIG. 1 is obtained.

At this time, green sand (S) is blown from the side opposite to the cavity surface (3a), so the cavity surface (3a)
Filled with every detail. On the other hand, the compressed air blown together with the green sand (S) is discharged into the atmosphere from a vent hole (13) equipped with a vent plug (12).

Next, after removing the blow head from the upper part of the filling frame (8), the compression plate (14) is moved to the filling frame (8) using a cylinder (not shown).
The green sand (S) is press-fitted from above, and pressure is applied to the green sand (S) in the direction of the cavity surface (3a) to cause the green sand (S) to undergo primary compression hardening.

Next, the compression plate (14) and the filling frame (8) are raised to remove the compression plate (14) and the filling frame (8) is extracted. The protruding surplus green sand (S) that has been hardened by primary compression is scraped off by moving the scraper (I5) along the mold matching surface of the split core box (la). (Fig. 3) The above operation is also performed for the split core box (1b) like a rice cake, and green sand (S ) is maintained.

Next, after the split core boxes (1a) (1b) holding the green sand (S) that has been subjected to the primary compression hardening are molded together as shown in Fig. 4, they are attached to the mounting plate (16) and Green sand (S) is poured from the open part (4) of the split core box (la) (lb) made by matching the rod member (17) whose tip is shaped like an inverted cone.
The mounting plate (16) is pushed into the opening (4) using a cylinder (not shown) until it is inserted into the opening. At this time, green sand (S) is transferred from the inside to the outer cavity surface (3a) (
Since it is compressed toward 3b), the green sand on the mold mating surfaces that are in contact with each other is integrated and simultaneously hardened by secondary compression.

Next, after lifting the rod member (17) and removing it, the push-out pins (5a) (5b) and push-out plates (6a) (6b) are removed.
The split core boxes (la) and (1b) are divided while being acted on appropriately, and the molded green sand core is taken out to complete the molding of the green sand core.

Even when the surface shape of the green sand core formed in this way is complex, the shape of the mold is accurately transferred, the entire core is integrated, and it has been confirmed that it has sufficient hardness. Ta.

In the above example, the primary compression hardening of green sand (S) is as follows:
Green sand (S) is blown into the cavity containing the filling frame (8) together with compressed air and then compressed by the compression plate (14). As shown in Fig. 6, the split core box (1a)
A vent plug (20) is installed in the split core box (1
Green sand (s) is introduced by dropping into the cavity composed of a), the plate member (7), and the filling frame (8), and then an air supply box (22) with air supply holes (21) provided on the lower surface is installed. The green sand (s) may be compressed and hardened by pressing it onto the upper surface of the filling frame (8) and supplying compressed air into the air supply box (22).

In this case, the compressed air supplied to the air supply box (22) is blown out from the air supply hole (21), passes through the green sand (s), passes through the vent plug (20), and is released to the atmosphere. (S) is the cavity surface (
It will be compression hardened towards 3a).

Further, in the above case, compressed air is impulsively applied to the green sand (S) without providing a vent plug (20) in the split core box (1a).
) Green sand (S) can also be similarly compressed by acting on the upper part.

Furthermore, in the above embodiment, after the green sand (s) is compressed and hardened, the excess sand is scraped off with a scraper (15), but the height of the filling frame (8) or the amount of sand introduced is adjusted, and the compression plate ( By making the descending distance in step 4 up to the mold matching surface of the split core box (1a), it is possible to eliminate the need for scraping with the scraper (15).

Furthermore, in the embodiment described above, the rod member (17) is inserted on the extension line of the mold matching surface of the split core boxes (la) and (lb) as shown in FIG. It is also possible to increase the number of core boxes and insert them at positions shifted from the extension line of the mold matching surfaces of the core boxes (la) (lb).

Further, in the above embodiment, the rod member (17) is extracted from the green sand after secondary compression hardening, but it may also be cut off from the mounting plate (16) and left in the green sand to be used as a core metal. good.

(Effects) As is clear from the above description, the present invention involves filling green sand into a split core box that is easy to fill, compressing it for the first time, and
Furthermore, since the core is molded by performing secondary compression using a rod member to integrate the divided molded cores and performing secondary compression, the molded core is molded over the details of the cavity of the core box. The sand is filled and compressed, and even if the core has a complicated shape, the shape of the mold is accurately transferred and molded, and a strong core is produced, which is an excellent effect.

[Brief explanation of the drawing]

The figures show the implementation steps of the present invention; FIG. 1 is a cross-sectional view showing the green sand filled state, FIG. 2 is a cross-sectional view showing the green sand in the primary compression hardening state, and FIG. FIG. 4 is a sectional view showing the scraped state of green sand, FIG. 4 is a sectional view showing the secondary compression state, FIG. 5 is a view taken along the line X-X in FIG. 4, and FIG. A cross section showing another example of compression hardening, FIG.
FIG. 7 is a cross-sectional view showing another example of next compression. (la) (lb): Split core box (3a) (3b): Cavity surface (7): Plate member (8): Filling frame (9) Niblow tank (14): Compression plate (17): Bar material Part (22): Air supply box grass 1 Figure ÷ 32

Claims (1)

[Claims] Green sand is introduced into the filling frame additional cavity of each split core box with a filling frame added to the molding surface, and pressure is applied to the introduced green sand toward the cavity surface of the split core box. The earth and sand were first compressed and hardened, and the upper surface of the green sand was made to match the molding surface of the split core boxes, and the plurality of split core boxes holding the green sand that had been hardened by the first compression were molded together. After that, a rod member whose tip end is approximately in the shape of an inverted cone is inserted into the green sand that is being held, and pressure is applied to the green sand from the inside to the outside, thereby forming each segmented sand. A method for molding green sand cores characterized by unifying earth and sand and at the same time performing secondary compression hardening.