JPH0688101B2 - Mold making method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for molding a mold which can be stably obtained irrespective of the property of the molding sand in which the hardness of the surface of the mold on the model side is introduced, particularly the water content thereof. .

[0002]

2. Description of the Related Art In order to prevent the occurrence of defects in casting products due to unevenness or lack of hardness on the model side of the mold, it is necessary to increase this hardness uniformly.
For this purpose, the technique of squeezing the foundry sand put into the flask from both upper and lower surfaces of the mold is well known. This double-sided squeeze generally involves squeezing a mold containing casting sand by descending the upper pressure head from above to pre-fill it, and then using a lower pressure head fixed integrally to the lower surface of the model surface plate. It is carried out by pushing up and squeezing from the model surface side, and finally squeezing again from above with the upper pressure head.

[0003]

By the way, in the above method, it is important that the model side end surface of the mold and the molding frame end surface are flush with each other after squeezing from both upper and lower surfaces. For that purpose, measures such as setting the squeeze stroke amount of the lower pressurizing head to a small amount and setting the pre-filling pressurizing force of the upper pressurizing head to a small amount are taken. However, with such measures,
If the compression margin of the molding sand is small, the model side end surface of the mold does not reach the molding frame end surface, and conversely, if the molding sand compression margin is large, the model side end surface of the mold is on the same plane as the molding frame end surface. However, there is a drawback that sufficient hardness cannot be obtained at the model side end surface of the mold due to insufficient pressurization.

Furthermore, the temperature of the recovered sand after casting largely changes depending on the amount of casting sand used per unit weight of the casting, that is, the sand metal ratio, the elapsed time until the product is removed after casting, and the recovered sand is the main constituent. The moisture content of the prepared foundry sand, even when constant at the time of preparation, changes significantly due to the influence of the temperature of the recovered sand, the residence time during the transfer of the foundry sand, the temperature of the outside air, etc. Make a difference. However, depending on the conventional mold making method and apparatus, it is not possible to adjust the property of the molding sand, particularly the compression amount of the molding sand put into the flask in response to the change of the water content, and therefore the mold Stable hardness cannot be obtained on the model side. The present invention is a property of foundry sand,
In particular, in response to a change in the water content, adjusting the compression amount of the molding sand put into the flask, the mold molding method that enables the production of a mold having a stable hardness on the model side of the mold and The purpose is to provide a device.

[0005]

In order to solve the above-mentioned problems, a method of molding a mold according to the present invention is a model on the upper surface of a lower pressurizing head movably fitted vertically along the inner side surface of an auxiliary frame. After fixing the surface plate and placing the casting frame on the auxiliary frame,
The lower pressurizing head is lowered and held at a predetermined position, and casting sand is put into the space formed by the inner surface of the casting frame, the inner surface of the auxiliary frame, and the upper surface of the model surface plate, In the mold making method of squeezing the charged molding sand by the upper pressure head and the lower pressure head that can be moved directly above the molding frame, the water content of the molding sand during the charging is measured. Step 1 and the squeeze stroke amount of the lower pressurizing head required for the molding sand to obtain a predetermined hardness on the basis of the measured water content, and in order to secure this stroke amount, A second step of moving the pressurizing head up and down in advance from the lowered position to position the casting head, the casting sand is put into the space, and the top addition is performed after the first and second steps are completed. Pressure head and lower pressure head A casting mold making method, characterized in that each squeezing by.

Further, the mold making apparatus according to the present invention includes an auxiliary frame, a casting frame placed on the upper surface of the auxiliary frame, and a lower addition member vertically movably fitted along the inner side surface of the auxiliary frame. Pressure head, a model surface plate fixed to the upper surface of the lower pressure head, an upper pressure head movable directly above the flask, and an inner surface of the flask which is arranged above the flask. In the mold molding apparatus having a molding sand charging means for charging molding sand into the space formed by the inner surface of the auxiliary frame and the upper surface of the model surface plate, the water content of the molding sand being charged into the space The water content measuring means for measuring the content, the position detecting means for detecting the vertical position of the lower pressurizing head, and the electronic control means respectively connected to the water content measuring means and the position detecting means, The electronic control means is based on the signal indicating the measured water content. Determines the squeeze stroke amount of the lower pressurizing head required for the molding sand to obtain a predetermined hardness, and in order to secure this stroke amount, the lower pressurizing head based on a signal from the position detecting means. The lower pressurizing head is moved up and down in advance to position it, and the hardness of the molding sand put into the space after squeezing by the upper pressurizing head and the lower pressurizing head is thereby controlled. A mold making apparatus characterized by being adjustable based on the water content of sand.

[0007]

The hardness of the foundry sand put into the mold is generally increased by the squeeze from above and below, and the obtained hardness depends on the degree of compression of the foundry sand. However, the compressibility of the foundry sand is greatly influenced by the properties of the foundry sand, especially the water content thereof. Therefore, in order to give the desired hardness to the foundry sand by the squeeze, the stroke amount of the squeeze must be accurately adjusted according to its water content. The properties of the foundry sand, especially its water content, are measured to calculate the amount of compression to give the desired foundry hardness, and the amount of squeeze stroke of the lower pressurizing head required for this amount of compression is determined. Then, the lower pressurizing head is moved up and down in advance before the squeeze so as to just leave this squeeze stroke amount and positioned. Therefore, it is possible to apply an appropriate amount of squeeze from the model surface plate side to the respective molding sands having different water contents and thus compressibility, and the surface of the model side is stable and has a desired hardness. A mold can be manufactured. Further, at the stage where the squeeze by the lower pressurizing head is finished, the model side end surface of the mold and the molding frame end surface can be in exactly the same plane.

[0008]

Embodiment An embodiment of the present invention will be described below with reference to FIG. The mold making apparatus of the present invention includes an auxiliary frame 1, a casting frame 2 placed on the upper surface of the auxiliary frame 1, and a lower pressure head 3 vertically movably fitted along the inner side surface of the auxiliary frame 1. And a model surface plate 4 fixed to the upper surface of the lower pressurizing head 3, and an upper pressurizing head 5 that is movable immediately above the casting frame 2. The lower pressurizing head 3 is supported by a lower pressurizing cylinder 6 so as to be vertically movable. The upper pressurizing head 5 includes an upper pressurizing cylinder 7
It is supported by the upper pressure cylinder 7 so that it can move up and down.
Is fixed to the frame 8, and the frame 8 can be laterally moved from the position indicated by the solid line in the figure to the position indicated by the chain line immediately above the casting frame 2 by a moving device (not shown). Further, a stopper cylinder 9 is fixed to the lower surface of the frame 8, and a piston rod 10 that is vertically movable and is fitted downward is fitted to the stopper cylinder 9. The foundry sand feeding device 11 is provided above the frame 8 and can move the foundry sand 12 into the casting frame 2 by moving the frame 8 in the lateral direction. A water content measuring device 13 for measuring the water content in the molding sand at the time of charging the molding sand outlet of the molding sand charging device 11.
Is attached. A position detector 14 for detecting the vertical position of the lower pressurizing head 3 is attached. The electronic control unit 15 is connected to the moisture measuring device 13, the position detector 14, etc. by a well-known microcomputer. The electronic control unit 15 executes the operation of this molding machine as well as the relationship between the hardness of the molding sand, the compression amount and the water content, the data of the squeeze stroke amount of the lower pressurizing head corresponding to the compression amount. The programs and the like are stored.

Next, a molding method using the mold molding apparatus of the present invention will be described. In FIG. 1, the lower pressurizing head 3 is stopped at the lowermost position by the lowering of a piston (not shown) fitted in the lower pressurizing cylinder 6. Frame 8
Is stopped at a position indicated by a solid line which is moved laterally from directly above the casting frame 2.

Next, the molding sand 1 is fed by the molding sand feeding device 11.
2 is put into the space formed by the inner surface of the casting frame 2, the inner surface of the auxiliary frame 1, and the upper surface of the model surface plate 4. The water content of the molding sand during the charging is measured by the water content measuring device 13, and the result is input to the electronic control unit 15 as a signal. In the electronic control unit 15, the compression amount of the molding sand for obtaining the desired hardness of the molding sand based on the signal and the squeeze stroke amount of the lower pressurizing head 3 required for this compression amount are stored inside. Determined from the existing data. Based on this determination and the signal from the position detector 14 of the lower pressurizing head, the electronic control unit 15 controls the operation of the lower pressurizing head 3 until the required squeeze stroke amount is left. Raise 3 in advance. Lower pressure head 3
Fig. 2 shows the state when the robot moves up to the position where the squeeze starts.
It shows in (a).

FIG. 2 (b) shows a state in which the frame 8 has moved to a position directly above the casting frame 2 and the upper pressurizing head 5 has descended to squeeze the input molding sand from above to prefill it. In this case, the upper pressurizing head 5 is fixed at the lowered position, and the piston rod 10 is lowered and fixed until it comes into contact with the upper end surface of the casting flask 2 to press the casting flask 2 from above.

In FIG. 2 (c), the lower pressurizing head 3 is lifted by a predetermined stroke amount so that the upper surface of the model surface plate 4 has the casting frame 2
The state where the squeeze from the model surface side is performed until the surface is flush with the lower end surface of

FIG. 2D shows a state in which the lower pressurizing head 3 is lowered and released from the mold. In this case, the upper pressurizing head 5 and the piston rod 10 are simultaneously raised to complete the molding process. After the squeeze from the model surface side shown in FIG. 2C, the upper pressurizing head 5 may be lowered again to squeeze the mold from above.

As the water content measuring device 13, a conventional one can be used, and as the position detector 14, other than the rack and pinion system, another system can be adopted.

As is clear from the above description, according to the mold making method and apparatus of the present invention, the properties of the foundry sand put into the flask, particularly the water content thereof, are measured to obtain the desired foundry sand hardness. Calculate the amount of compression to give, determine the amount of squeeze stroke of the lower pressurizing head required for the calculated amount of compression, and before squeezing the lower pressurizing head so that this squeeze stroke amount remains exactly. Move it up and down in advance to position it. Therefore, it is possible to apply an appropriate amount of squeeze from the model surface plate side to the respective molding sands having different water contents and thus compressibility, and the surface of the model side is stable and has a desired hardness. A mold can be manufactured. Further, at the stage where the squeeze by the lower pressurizing head is finished, the model side end surface of the mold and the casting frame end surface can be in exactly the same plane.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a casting mold making apparatus according to the present invention before casting of molding sand.

FIG. 2 is a schematic vertical sectional view showing a mold making process by the mold making apparatus of FIG.

[Explanation of symbols] 1 auxiliary frame 2 casting frame 3 lower pressure head 4 model surface plate 5 upper pressure head 11 molding sand feeding device 12 molding sand 13 moisture measuring device 14 position detector 15 electronic control device

Claims (2)

[Claims] 1. A model surface plate is fixed to the upper surface of a lower pressure head movably fitted vertically along the inner surface of the auxiliary frame, and the casting frame is placed on the auxiliary frame, and then the lower frame The pressing head is lowered to a predetermined position and held, and casting sand is put into a space formed by the inner side surface of the casting frame, the inner side surface of the auxiliary frame and the upper surface of the model surface plate, and this feeding In a mold making method of squeezing the formed molding sand by an upper pressure head and a lower pressure head that can be moved directly above the molding frame, first measuring the water content of the molding sand during the charging. Step, and based on the measured water content, the squeeze stroke amount of the lower pressurizing head required for the molding sand to obtain a predetermined hardness is determined, and the lower pressurizing pressure is applied to secure this stroke amount. Move the head up and down in advance from the lowered position A second step of positioning,
A casting mold making method, characterized in that casting sand is put into the space, and after the first and second steps are finished, squeezing is performed by the upper pressure head and the lower pressure head, respectively. 2. An auxiliary frame, a casting frame placed on an upper surface of the auxiliary frame, a lower pressure head movably fitted vertically along an inner side surface of the auxiliary frame, and a lower pressure applied to the lower frame. A model surface plate fixed to the upper surface of the head, an upper pressurizing head movable immediately above the casting frame, an inner side surface of the casting frame disposed above the casting frame and an inner side surface of the auxiliary frame. In a mold making apparatus having a molding sand charging means for charging molding sand into the space formed by the upper surface of the model surface plate, a water content measurement for measuring the water content of the molding sand being charged into the space Means and
Position detection means for detecting the vertical position of the lower pressurizing head, and electronic control means respectively connected to the water content measuring means and the position detection means, the electronic control means for measuring the measured water content. Based on the signal from the position detecting means to determine the squeeze stroke amount of the lower pressurizing head required to obtain the predetermined hardness of the molding sand based on the signal shown, and to secure this stroke amount. The operation of the lower pressurizing head is controlled and the lower pressurizing head is moved up and down in advance so as to be positioned, so that the squeeze of the molding sand put into the space by the upper and lower pressurizing heads is performed. A mold making apparatus, wherein hardness can be adjusted based on a water content of the foundry sand.