JPH09285841A - Molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mold a mold of uniform ramming by filling the molding sand in advance, compressing the molding sand near a peripheral edge part in a molding flask by an annular body made of sheet, and pressing the whole molding sand. SOLUTION: A pattern plate 2 is loaded on a base 1, and a molding flask 3 and a cheek 4 are stacked thereon to demarcate the space. The molding sand S is charged is in the space. The compressed air is fed to an upper part of the molding sand S to fill the molding sand S in the vicinity of the pattern plate 2 in advance. Then, a fitting plate 7 is fitted to a lower end of a piston rod 6, and a preliminary compressing means fitted with a relatively small cylindrical annular body 8 made of sheet opposite to an inner surface of the molding flask 3 and the cheek 4 on a lower surface of the fitting plate 7 is arranged on the cheek 4. The annular body 8 made of sheet is inserted and pressed down toward the pattern plate 2 from the top of the molding sand 8 to preliminarily press the molding sand S in a part close to the inner surface of the molding flask 3 at an upper part of the pattern plate 2. Then, the annular body 8 made of sheet is drawn, and the whole molding sand S is pressed using a pressing plate to perform the ramming.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of pressing a molding sand put into a space defined by a pattern plate and a molding frame to mold it.

[0002]

2. Description of the Related Art Conventionally, in the molding of a mold by pressing as described above, there is a tendency that the mold clamping in a portion close to the pattern plate is insufficient. In particular, the mold clamping was poor at the lower end of the peripheral edge of the mold (the position farthest from the upper surface of the molding sand, which is the position closer to the molding frame of the pattern plate) near the inner surface of the molding frame.
This is because when the casting sand is put into the casting frame, the sand density in the portion close to the casting wall inner wall tends to be small, and the influence of friction with the casting frame inner wall surface when pressing the casting sand. This is because the pressing force is difficult to be transmitted to the foundry sand in this portion. Such a mold having a part with poor mold clamping is liable to lose its shape and is easily deformed at the time of pouring, so that a sound casting with good dimensional accuracy cannot be obtained. For this reason, in order to obtain sufficient mold clamping even near the pattern plate, pre-filling with a jolt is performed prior to pressing the entire mold sand, or compressed air is applied to the molding sand to form the molding sand. Are precompressed.

[0003]

However, even if pre-filling is performed by the action of jolt or compressed air prior to pressing the entire molding sand as described above, the inner surface of the molding frame at the upper part of the pattern plate is The mold clamping at the lower end of the peripheral edge of the mold tended to be insufficient. Therefore, in order to obtain uniform and firm mold clamping over the entire mold, it is necessary to perform pre-filling more strongly, and in order to perform these pre-filling strongly, the device must be more robust and large-sized. The cause of noise and vibration is increased, which is a big problem. The present invention is made in view of the above problems, and mold molding is performed by improving mold clamping in a portion near the pattern plate in the peripheral portion of the mold close to the inner surface of the mold, where mold clamping of the foundry sand tends to be insufficient. The purpose is to provide a method of doing.

[0004]

A method for molding a mold according to the first aspect of the present invention for achieving the above object is a pattern press.
A sand charging step in which a molding flask is installed on the upper part of the mold, and the molding sand is charged into the space defined by the pattern plate and the molding flask,
A pre-filling step of increasing the sand filling density of the portion of the cast molding sand close to the pattern plate, and a tubular thin plate-shaped annular body relatively small with respect to the inner surface of the casting frame, above the casting sand. From the pre-compressing step of compressing the molding sand near the inner surface of the molding frame in the upper part of the pattern plate by relatively pushing down the molding sand from the molding sand, and after extracting the thin plate annular body from the molding sand. In the mold making method of the second invention, the order of the pre-filling step and the pre-compressing step is reversed. It is characterized by that.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. A pattern plate 2 having a pattern 2A mounted thereon is placed on a base 1 having a ventilation opening 1A at the center thereof so as to straddle the ventilation opening 1A, and on the pattern plate 2 The casting frame 3 and the filling frame 4 are stacked and placed, and a space is defined by the pattern plate 2, the casting frame 3 and the filling frame 4. The pattern plate 2 is provided with a vent hole 2B for allowing compressed air to pass through, and a vent plug 2C is driven into each vent hole 2B. Next, the molding sand S is charged into the space defined by the pattern plate 2, the casting frame 3 and the filling frame 4, the upper surface of the filling frame 4 is leveled, and the state of FIG.

Next, the cover member 5 communicating with the compressed air source P via the opening / closing valve 5A is placed on the upper part of the filling frame 4, and the opening / closing valve 5A is opened to send the compressed air to the upper part of the foundry sand S. As a result, the compressed air flows through the molding sand S and is exhausted from the vent holes 2B, 2B to pre-fill the molding sand S in the portion close to the pattern plate 2 to the state shown in FIG. The on-off valve 5A is closed and the prefilling process is completed, and the cover member 5 is moved from the upper portion of the filling frame 4. Next, a mounting plate 7 is attached to the lower end of the piston rod 6 that can be moved up and down, and the entire lower surface of the mounting plate 7 is a thin plate annular shape that is a relatively small tubular shape with respect to the inner surfaces of the casting frame 3 and the filling frame 4. The precompression means with the body 8 attached is located above the fill frame 4. At this time, the thin plate annular body 8 is brought into a state corresponding to the vicinity of the inner surfaces of the filling frame 4 and the casting frame 3. In this state, the piston rod 6 descends to lower the thin plate annular body 8 via the mounting plate 7 and insert and push down the casting sand S from above the pattern plate 2 toward the pattern plate 2. -At a position slightly higher than G2, the descent is stopped and the state shown in Fig. 3 is obtained. As a result, the molding sand S in the upper portion of the pattern plate 2 near the inner surface of the casting frame 3 (the lower end of the peripheral edge of the mold) is compressed, and the preliminary compression step is completed.

Next, the piston rod 6 is reversely operated to pull out the thin plate annular body 8 from the molding sand S and move the preliminary compression means from the upper part of the filling frame 4. Next, the pressing means in which the pressing plate 10 is attached to the lower end of the elevating rod 9 is positioned above the filling frame 4, and the elevating rod 9 is lowered to lower the pressing plate 10 to the lower end position of the filling frame 4 (see FIG. State) The entire casting sand S is pressed. As a result, the entire molding sand is clamped and the pressing process is completed. Next, the elevating rod 9 is reversely actuated, the pressing plate 10 is lifted above the filling frame 4 to move the pressing means from the upper portion of the filling frame 4, and then the casting frame 3 is separated from the filling frame 4, and the casting frame 3 is separated.
And the pattern plate 2 are separated from each other, and normal molds are taken out.

In the above embodiment, the mold making is performed in the order of the sand charging step, the preliminary filling step, the preliminary compression step, and the pressing step, but the preliminary filling step and the preliminary compression step are performed in this order. It was confirmed that similar effects can be obtained even if the components are replaced. Furthermore, the pre-filling of the foundry sand is done with a pattern.
The compressed air may be abruptly applied to the upper portion of the molding sand without providing the vent hole 2B in the template 2.
Further, in the pre-filling step, the same operation and effect can be obtained also by the jolt vibration in which the cast molding sand S that has been introduced is moved up and down together with the pattern plate 2, the casting frame 3 and the filling frame 4. Further, if the thin plate annular body 8 is too thick, the void groove formed when it is extracted from the molding sand S becomes large, and the void groove will not disappear even if pressed by the pressing plate thereafter. Therefore, the thickness can be set to 20 mm or less. desirable. In addition, thin plate annular body 8
May be partially cut as shown in FIG. Further, the pressing step is performed by one pressing plate 10, but a large number of segment squeeze hoods,
A pressing method using a diaphragm or the like may be adopted.

[0009]

As is apparent from the above description, the present invention pre-fills the molding sand in the portion close to the pattern plate which is apt to lack mold clamping, and the pattern is formed in the peripheral portion of the mold close to the inner surface of the mold. -The molding sand near the plate is pre-compressed by the thin plate annular body (including the case of changing the order of pre-filling and pre-compression), and then the whole molding sand is pressed to form the mold. A mold with a closed mold can be produced. Further, in the present invention, the pre-filling is not made to be strong but is made up by the pre-compression by the thin plate annular body having a simple mechanism, so that it is not necessary to make the apparatus robust and large.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a state in which foundry sand is charged.

FIG. 2 is a vertical cross-sectional view showing a pre-filled state of foundry sand.

FIG. 3 is a vertical cross-sectional view showing a state of preliminary compression of foundry sand.

FIG. 4 is a vertical cross-sectional view showing a pressed state of foundry sand.

FIG. 5 is a view taken in the direction of arrows AA in FIG. 4;

6 is a view on arrow AA showing another thin plate annular body in FIG. 4. FIG.

[Explanation of symbols]

 2 Pattern Plate 3 Casting Frame 4 Filling Frame 5 Cover Member 8 Thin Plate Annular Body 10 Pressing Plate S Cast Sand

Claims (4)

[Claims] 1. A sand charging step of setting a casting frame on the upper part of a pattern plate and charging casting sand to a space defined by the pattern plate and the casting frame, and the casting process. A pre-filling step for increasing the sand filling density in the portion of the sand close to the pattern plate, and a cylindrical thin plate annular body that is relatively small with respect to the inner surface of the casting frame, is applied from above the casting sand to the pattern plate. Precompressing step of compressing the molding sand in the vicinity of the inner surface of the molding frame in the upper part of the pattern plate by relatively pushing down the molding sand, and after pulling out the thin plate annular body from the molding sand, the entire upper surface of the molding sand And a pressing step of pressing the pressing means with a pressing means. 2. A sand feeding step of placing a casting frame on the upper part of the pattern plate and feeding casting sand into a space defined by the pattern plate and the casting frame; and an inner surface of the casting frame. A relatively small tubular annular member is inserted into and pushed down from the molding sand toward the pattern plate, and the molding sand near the inner surface of the molding frame at the upper part of the pattern plate is pushed down. A pre-compression step of compressing the thin plate annular body from the molding sand, and a pre-filling step of increasing the sand packing density of the portion of the cast molding sand close to the pattern plate,
And a pressing step of pressing the entire top surface of the foundry sand with a pressing means. 3. The mold making method according to claim 1, wherein the preliminary filling step causes compressed air to act on the input molding sand. 4. The pre-filling step is performed by Jolt vibration for vertically vibrating the charged molding sand together with the pattern plate and the flask.
Alternatively, the casting method according to claim 2.