JP3802358B2 - Casting sand compression method and casting sand molding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method suitable for compressing foundry sand in a mold making space and a foundry sand molding method using the method .
[0002]
[Prior art and issues]
Conventionally, as a method for compressing foundry sand filled in a mold forming space defined by a model plate and a casting frame, there is a method in which a model plate and a compression means are brought close to each other. . However, this method requires a large hydraulic cylinder for raising and lowering the model plate, and as a result, the mold making machine has a high height, and it is necessary to provide a pit for installation. there were. Further, it is unstable when separating the mold from the model plate, and it is difficult to reduce the draft angle. If the draft is large, the weight of the casting becomes large, which is not preferable. Furthermore, the compression conditions could not be easily changed even if the properties of the foundry sand changed.
[0003]
The present invention has been made in view of the above circumstances, and its purpose is to mold a mold defined by a model plate and a frame member without providing a large hydraulic cylinder for lifting the model plate that requires a pit. An object of the present invention is to provide a method capable of compressing a foundry sand in a space to a required hardness almost entirely. Another object of the present invention is to provide a method for compressing foundry sand that can reduce the draft as much as possible. It is another object of the present invention to provide a method for compressing foundry sand in which the mold height is uniform under optimum compression conditions even if the properties of foundry sand change. Further, a molding sand molding method using the molding sand compression method is provided.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the method for compressing foundry sand according to the present invention includes at least a model plate that is horizontally fixed when the foundry sand is compressed, and a cylinder that is mounted on the model plate so as to be slidable up and down. The molding sand in the mold molding space defined by the leveling frame arranged so as to be able to be raised and lowered and the frame member arranged so as to be able to be raised and lowered above the leveling frame. And
Introducing casting sand into the mold making space;
A first compression step of compressing the beam of which a molding sand of the molding space under impossible lowered position upwardly or al compression means, - at least the leveling frame
A second compression step of further compressing the molding sand in the mold making space under the state in which the leveling frame and the frame member can be lowered;
Have a, the leveling frame against the downward pressure of the compression means from above at the first compressing step - the upward pressure of the arm is held by hydraulic pressure of the cylinder, also the on time of switching to the second compression step leveling at the end compressed by opening the hydraulic cylinder frame - increase the pressure of the beam is characterized by substantial without a Rukoto.
Further, the molding sand molding method of the present invention comprises a lifting frame constructed on a hydraulic cylinder standing on a surface plate, and a compression means disposed on the lifting frame, in 1 compression method foundry sand 12 wherein, after the second compression step, wherein the leveling frame - characterized in that it comprises a step of raising the arm at a rate above not later than the rising speed of the hydraulic cylinder.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the frame member means a cast frame when the mold to be molded has a cast frame, and means a mold frame when there is no cast frame. The mold to be molded includes a case with a cast frame and a case without a cast frame extracted from the mold after the foundry sand is solidified in the mold. Furthermore, although the compression force by the compression means in the second compression step may be substantially the same as that in the first compression step, the effect of the present invention can be enhanced by increasing the compression force. Further, in the present invention, the compression means has various structures, the one that compresses the foundry sand is integrated, the one that is divided into a plurality of parts, and the flexibility that the pressure fluid acts on the back surface. Some have increased flexibility with a membrane. Further, after the step of adjusting the volume of the mold making space, casting sand may be put into the mold making space. If it does in this way, compression conditions can be determined easily corresponding to the change of foundry sand.
[0006]
[Example 1]
An embodiment of a mold making machine to which the present invention is applied will be described in detail with reference to the drawings. The mold making machine includes a model plate 1 that is horizontally fixed, a leveling frame 2 that is mounted on the model plate 1 so as to be slidable up and down, and that can be moved up and down, and the leveling frame. A casting frame 3 as a frame member disposed so as to be movable up and down above the frame 2, a fill frame 4 disposed so as to be movable up and down above the casting frame 3, and capable of moving up and down above the casting frame 3. The compression means 5 which is disposed and the lower part can enter at least the filling frame 4 is constituted.
[0007]
And the said model board 1 is attached to the upper surface of the below-mentioned turntable 19, Furthermore, the vent plug (not shown) is embed | buried under the upper surface of the model board 1 depending on the shape of a model. The leveling frame 2 attached to a turntable 19 described later is moved up and down by a plurality of hydraulic cylinders 6 and 6 as leveling frame lifting mechanisms mounted on the turntable 19 described later. The casting frame 3 can be moved in the front-rear direction by a transport mechanism 9 that is pivotally supported by the frames 8, 8 at a suitable interval in the front-rear direction with a plurality of flanged rollers 7, 7. The transport mechanism 9 is attached to the lifting frame 10. The lifting frame 10 is installed between the upper ends of the piston rods of the two hydraulic cylinders 12 and 13 erected on the left and right sides of the table-like machine base 11, and is expanded and contracted by the hydraulic cylinders 12 and 13. It is designed to go up and down.
[0008]
The filling frame 4 is constructed between the lower ends of piston rods of downward hydraulic cylinders 14 and 14 mounted on the frames 8 and 8. The compression means 5 can run in the front-rear direction on the rails 20, 20 attached to the frames 8, 8 and extending in the front-rear direction via a plurality of flanged rollers 21, 21 supported on the side surfaces. And has a plurality of rectangular parallelepiped compression members 18 and 18 that can be raised and lowered. A casting sand weighing hopper (not shown) is mounted on the rails 20 and 20 so as to be able to travel in the front-rear direction. Further, the left hydraulic cylinder 12 of the two hydraulic cylinders 12 and 13 is provided with a center of a turn table 19 as a model loading / unloading means extending in the left-right direction so as to be intermittently horizontally rotatable. It is attached.
[0009]
Next, a procedure for putting casting sand into a predetermined mold making space and compressing it will be described. First, under the state in which the hydraulic cylinders 6 and 6 are extended and the leveling frame 2 is raised, the hydraulic cylinders 12 and 13 are contracted to the required length to lower the lifting frame 10 and the leveling frame 2 is lowered. The casting frame 3 is placed thereon, and then the hydraulic cylinders 14 and 14 are extended to overlap the filling frame 4 on the casting frame 3 to define a mold making space.
[0010]
Next, a required amount of foundry sand is put into the mold making space from the weighing hopper, and then the weighing hopper is carried out and the compression means 5 is carried just above the filling frame 4. Subsequently, the leveling frame 2 cannot be lowered when the hydraulic cylinders 6 and 6 are contracted so that the oil cannot be discharged from the oil discharge side, and the oil can be discharged from the oil discharge side when the hydraulic cylinders 14 and 14 are contracted. Under the state, the compression members 18 and 18 of the compression means 5 are contracted independently to compress the foundry sand, and the hydraulic cylinders 12 and 13 are contracted to operate the compression means 5 through the lifting frame 10 as appropriate. Lower the length of. As a result, the foundry sand in the mold making space is first compressed (see FIG. 1).
[0011]
Next, when the hydraulic cylinders 6 and 6 are contracted, the leveling frame 2 can be lowered so that the oil can be discharged from the oil discharge side, and the hydraulic cylinders 14 and 14 cannot be discharged so that they cannot expand and contract. The hydraulic cylinders 12 and 13 are further contracted to lower the compression means 5, the casting frame 3 and the filling frame 4. Then, the leveling frame 2 is pushed down through the casting frame 3 and the filling frame 4, and the casting sand is lowered together with the casting frame 3 and pressed against the model plate 1 as a result. The foundry sand will be further compressed.
[0012]
After completion of the compression of the foundry sand, the compression members 18 and 18 are raised, and the hydraulic cylinders 12 and 13 are extended while the hydraulic cylinders 6 and 6 are extended to raise the compression means 5, the filling frame 4 and the like, and molding The cast frame 3 containing the cast mold is lifted by engaging the collar rollers 7 and 7 and separated from the model plate 1. Thereafter, the turntable 19 is rotated 180 degrees horizontally to move another model plate 1 directly below the compression means 5, and the weighing hopper is replenished with foundry sand, and another empty casting frame 3 is placed on the transport mechanism 9. Carry in and complete one cycle.
[0013]
In the above-described embodiment, the molded mold is provided with the casting frame 3, but it may be without the frame extruded from the molding frame. Further, the fill frame 4 may be omitted.
[0014]
[Example 2]
Another embodiment of the mold making machine to which the present invention is applied will be described in detail with reference to the drawings.
In FIG. 2, frame set cylinders 102 and 102 are erected upward on both the left and right sides of the molding base 101, and a lifting support frame is provided between the piston rods 102A and 102A of the frame set cylinders 102 and 102. 103 is erected. That is, the frame set cylinders 102 and 102 are erected with the molding base 101 side as a contracted end and facing upward.
[0015]
A central portion of the pattern changing device 104 is rotatably supported in a horizontal plane below one of the frame setting cylinders 102 (left side in FIG. 2). Pattern carriers 106 and 106A on which model plates 105 and 105A (upper and lower model plates) are placed are set at both ends of the plate in a state where the pattern carriers 106 and 106A are lifted by about 5 mm by a spring (not shown). It is made to carry in / out alternately by the center upper part of the molding base 101. FIG.
[0016]
The pattern - at four corners outside position below the pattern plate 105,105A in emissions carriers 106, 106 a,抜上up cylinders 107,107A is be embedded in the molding base 101 in the upward, the pin 124,124A at its front end Frame-shaped leveling frames 108 and 108A that surround the outer periphery of the model plates 105 and 105A and slide up and down are supported. The leveling frames 108 and 108A protrude slightly upward (see FIG. 3) from the parting surfaces of the model plates 105 and 105A at the extended ends of the pull-out cylinders 107 and 107A, and the model plates 105 and 105A at the contracted ends. It is designed to be substantially the same plane as the parting plane (see FIG. 5). The pulling cylinders 107 and 107A have an output for lifting and removing the casting frame 120 as a frame member containing the leveling frame 108 and the mold, and this output raises the frame setting cylinders 102 and 102. There is no output. Further, the pattern carrier 106 is provided with a clamp member (not shown), and the molding base 101 is provided with a clamp device (not shown) for clamping the clamp member. The pattern carrier 106 is crimped onto the molding base 101 by pulling and clamping the clamp member with the clamping device.
[0017]
The elevating support frame 103 is provided with a sand inlet 110 which is opened and closed by a slide gate 109 at the upper end, and a low pressure air (for example, 0.05 to 0.18 MPa) via a switching valve (not shown) on the upper side. A plurality of air ejection chambers (not shown) communicating with a compressed air source (not shown) through a switching valve (not shown) on the lower peripheral side and lower part inside. The provided sand hopper 112 is suspended. In addition, low-pressure air (for example, 0.05 to 0.18 MPa) is jetted into the sand hopper 112 from a large number of air ejection chambers, and is configured to perform airborne fluidization of the foundry sand S. ing.
Further, segment-type squeeze feet 113 and 113 as squeeze means and sand filling nozzles 114 and 114 are disposed around the squeeze feet 113 and 113 at the lower end of the sand hopper 112.
[0018]
Further, the segment type squeeze feet 113 and 113 and the sand filling nozzles 114 and 114 are surrounded so as to be movable up and down, and vent holes 115 and 115 leading to an exhaust control chamber (not shown) are perforated. A filling frame 116 is arranged in a manner connected to filling frame cylinders 117 and 117 provided downward on the lower side of the sand hopper 112. Further, on the left and right outer positions of the sand hopper 112 in the lifting support frame 103, a carry-in / out conveyor 119 of the casting frame 120 is provided via frames 118, 118 extending to positions below the segment-type squeeze feet 113, 113. Is suspended.
[0019]
Next, the operation of the thus configured will be described in detail. The state shown in FIG. 2 is a state in which the foundry sand S is introduced into the sand hopper 112 and an empty casting frame 120 is carried into the carry-in / out conveyor 119. The pattern carrier 106 is set on the pattern exchanging device 104 in a state where it is lifted by about 5 mm by a spring (not shown), and there is a gap of about 5 mm between the pattern carrier 106 and the molding substrate 101.
Next, the entire segment-type squeeze foot 113, 113 forms unevenness relative to the unevenness of the lower model plate 105. Further, the leveling frame 108 is protruded upward from the parting surface of the model plate 105 by the pulling cylinders 107 and 107A. Then, the pattern carrier 106 is pressure-bonded onto the molding substrate 101 with a clamping device (not shown).
[0020]
In this state, the slide gate 109 is operated to close the sand inlet 110, and then the filling cylinders 117 and 117 are extended to lower the filling frame 116 to press and adhere to the upper surface of the casting frame 120 and set the frame. The cylinders 102 and 102 are contracted and the casting frame 120 is pressed onto the leveling frame 108 protruding upward on the outer periphery of the model plate 105, and the state shown in FIG. 3 is obtained.
[0021]
Next, a low-pressure air is ejected from a number of air ejection chambers into the sand hopper 112, and air supply pipes are connected via a switching valve (not shown) while airing to float and fluidize the foundry sand S in the sand hopper 112. The low pressure air from 111 is supplied to the sand hopper 112, and the casting sand S is filled in the molding space by low pressure air through the sand filling nozzles 114, 114 as shown in FIG. At this time, the low pressure air at the time of filling the air is exhausted from the vent hole (not shown) of the vent hole 115 and / or the model plate 105. The exhaust amount from the vent hole (not shown) of the model plate 105 can also be controlled by controlling the exhaust amount from the vent hole 115 in an exhaust control chamber (not shown). Thereby, the filling density of the foundry sand in the complicated shape portion of the model plate 105 in the molding space can be partially adjusted (FIG. 4).
[0022]
Next, the frame set cylinders 102 and 102 are further contracted to retract the elevating frame cylinders 117 and 117 while lowering the elevating support frame 103 and the members supported by the frame set cylinders 102 and 102. The primary squeeze as the first compression process of the foundry sand S is performed until the entire bottom surface of the feet 113, 113 becomes flat, and the sand gate 110 is opened by reversely operating the slide gate 109. At this time, the contraction operation of the frame set cylinders 102 and 102 is performed by the pressure sensor (not shown) reaching the set pressure of the primary squeeze or the encoder position (not shown) of the frame set cylinders 102 and 102 being the primary squeeze. Continue until the set position is reached.
[0023]
Next, by switching to the state in which the oil in the extraction cylinders 107 and 107A is released and the frame setting cylinders 102 and 102 are contracted at a pressure higher than the primary squeeze, the cast frame 120, the fill frame 116, and The squeeze feet 113 and 113 are integrally lowered, and the entire foundry sand S is subjected to secondary squeeze as a second compression step. As a result, the leveling frame 108 is lowered via the pins 124 and 124A due to the contraction of the pull-out cylinders 107 and 107A, and is brought to almost the same level as the parting surface of the model plate 105, resulting in the state shown in FIG.
If the squeeze pressure does not reach the set pressure of the secondary squeeze when the leveling frame 108 reaches the descending end, the frame set cylinders 102 and 102 are moved while the prime cylinders 117 and 117 are contracted. Further squeeze is performed by operating the contraction.
[0024]
Next, when the squeeze pressure reaches the set pressure of the secondary squeeze, the squeeze stabilization timer is activated to hold the squeeze for a predetermined time. At this time, in order to cope with the case where the leveling frame 108 has not reached the lowering end, the filling frame cylinders 117 and 117 are extended to lower the filling frame 116 and the leveling frame 108 reaches the lowering end. The casting frame 120 is pushed down. Thereby, the lower surface of the casting frame 120 and the lower surface of the mold can be made almost the same surface every time.
[0025]
The process of die-molding the mold-molded casting frame 120 formed in this way will be described below. When the secondary squeeze is completed as the second compression process to the foundry sand, the frame set cylinders 102 and 102 are at the contracted end. The withdrawal cylinder is also at the retracted end. Here, the frame setting cylinders 102 and 102 are raised at a low speed, and the extraction cylinders 107 and 107A are raised at a speed that is not slower than the frame setting cylinders 102 and 102. The speeds of the extraction cylinders 107 and 107A can be adjusted by applying hydraulic pressure to the hydraulic circuit.
[0026]
Here, the pull-out cylinders 107 and 107A have an output to lift and mold the leveling frame 108 and the casting frame 120 containing the mold, but there is no output to raise the frame setting cylinders 102 and 102. The border frame cylinders 117 and 117 are restrained by hydraulic pressure.
[0027]
For this reason, the squeeze feet 113 and 113 and the fill frame 116 are integrally raised as the frame set cylinders 102 and 102 are raised, and at the same time, the extraction cylinders 107 and 107A are moved at a speed that is not slower than the frame set cylinders 102 and 102. Since it is going to be raised, the casting frame 120 is separated from the model plate 105 by pressing the casting frame 120 to the fill frame 116 and raising it integrally through the leveling frame 108 by the extension operation of the extraction cylinders 107 and 107A. To do.
[0028]
At this time, the output of the frame setting cylinders 102 and 102 is large, the cylinder diameter is large, and the piston rods 102A and 102A of the frame setting cylinders 102 and 102 are pulled out in the most contracted state, so that the cutting accuracy is high. It has become. Further, the molded mold is slightly lifted from the stopped state together with the casting frame 120 and is removed.
[0029]
Thereafter, the fill frame 116 and the segment type squeeze feet 113 and 113 are raised together, and the mold-formed cast frame 120 is scooped up by the carry-in / out conveyor 119 and completely separated from the model plate 105. At the same time, the foundry sand S is replenished into the sand hopper 112 and the state shown in FIG. 6 is obtained.
[0030]
Next, the cast mold 120 is carried out via the carry-in / conveyor 119, the empty cast frame 120 is carried in, and the pattern changer 104 is rotated 180 degrees so that the model plate 105 and the model plate 105A are moved. The state is changed as shown in FIG. 7 and the above operation is repeated.
[0031]
Details of the operation of the leveling frame 108 during compression of the foundry sand are shown in FIG. FIG. 8 shows the operation of the leveling frame 108 in the compression process after casting sand is introduced into the mold making space. The molding sand is compressed by a first compression step in which the molding sand in the mold molding space is compressed by compression means from above under a state in which the leveling frame 108 cannot be lowered, a leveling frame, and a filling frame. And a second compression step of further compressing the foundry sand in the mold making space by the compression means under a state in which the frame member can be lowered.
[0032]
The first compression step has a hydraulic pressure that maintains the rising pressure of the leveling frame 108 against the downward pressure of the compression means from above, and the leveling frame is switched to the second compression step. -The hydraulic pressure of the frame 108 is released, and the hydraulic pressure for driving the leveling frame 108 is substantially eliminated at the end of compression. Accordingly, when the compressed mold is separated from the model plate, the mold is started in a state where the pressure of the leveling frame is substantially absent.
[0033]
Furthermore, the downward squeeze pressure from above by the compression means is further increased after switching to the second compression step. This determines the final compaction density of the foundry sand.
The switching pressure is variable.
[0034]
On the other hand, after the pressure for holding the fill frame downward reaches the maximum set pressure of the squeeze pressure in the first compression step, the pressure is held for a short time. This is to stabilize the second compression step.
[0035]
After releasing the pressure that holds the fill frame 116 downward, the squeeze pressure in the second compression step is held near the maximum set pressure . The squeeze pressure during this period stabilizes the squeeze. This time is preferably 1 to 2 seconds. This is because if the length is too long, the molding time increases.
[0036]
Before separating the mold after compression from the model plates 105 and 105A, a pressure is applied to hold the fill frame 116 downward. Thus, in order to cope with the case where the leveling frame 108 has not reached the lowering end, the filling frame cylinders 117 and 117 are extended to lower the filling frame 116 and the leveling frame 108 reaches the lowering end. The casting frame 120 is pushed down. As a result, the lower surface of the cast frame 120 after the mold release and the lower surface of the mold can be made substantially the same every time.
[0037]
Next, a control flow used for compression of the foundry sand is shown in FIG. In FIG. 9, first, in order to adjust the volume of the mold making space, the mold height after the second compression step for the previous mold making is measured, the difference from the target mold height is detected, and based on the difference. The value is calculated as a correction value. This correction is, for example, a value obtained by dividing the sand compression ratio by the difference between the mold height target value and the mold height. Then, the correction value is fed back to the target value of the volume of the mold space, more specifically to the frame set position. In the first molding, an initial value set in advance is used instead of the measured value.
[0038]
FIG. 10 shows an example of the result of the mold height feedback when the target mold height is 270 mm plus or minus 5 mm. In FIG. 10, since the initial frame setting position of the first time is 400 mm and the mold height is 280.2 mm, +10.2 mm with respect to the target value is subtracted from 400 mm, and the next frame setting target value is 389.8 mm. And By repeating this, the mold height converges to the target value. This mold height feedback control has made it possible to obtain a target mold height by molding several frames for changing sand properties and changing patterns.
[0039]
According to the present invention, there is a large effect on mold making and thus casting, such as drastically reducing the draft of conventional products and greatly reducing the amount of sand used.
[0040]
【The invention's effect】
As is apparent from the above description, the present invention includes a model plate that is horizontally fixed when the molding sand is compressed, and a leveling frame that is mounted on the model plate so as to be slidable in the vertical direction and is movable up and down. A casting in a mold forming space defined by a frame, a frame member disposed above and below the leveling frame, and a fill frame disposed above and below the frame member. A method of compressing sand, the step of throwing casting sand into the mold molding space, and compressing the molding sand of the mold molding space from above at least in a state where the leveling frame cannot be lowered. A first compression step of compressing by means, and a second compression step of further compressing the foundry sand in the mold making space by the compression means in a state in which the leveling frame, the filling frame and the frame member can descend. Because it has Without the need for a large hydraulic cylinder for lifting the model plate that requires a slab, the molding sand in the mold making space defined by the model plate and the casting frame is reliably compressed to the required hardness almost entirely. Excellent effects such as being possible. In addition, the draft can be made as small as possible, and even if the properties of the foundry sand change, excellent effects such as uniform mold height under optimum compression conditions can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing an embodiment of a mold making machine to which the present invention is applied.
FIG. 2 is a longitudinal sectional view showing a state before starting of an apparatus using the present invention.
FIG. 3 is a longitudinal sectional view showing a state where a molding space is defined.
FIG. 4 is a longitudinal sectional view showing an air filling state of foundry sand.
FIG. 5 is a longitudinal sectional view showing a squeezed state of foundry sand.
FIG. 6 is a longitudinal sectional view showing a state where a molding die is removed and casting sand is replenished.
FIG. 7 is a longitudinal sectional view showing a pattern change state.
FIG. 8 is a diagram showing details of the operation of the leveling frame during compression of the foundry sand according to the present invention.
FIG. 9 is a control flow used for compression of foundry sand according to the present invention.
FIG. 10 is an example of a result of mold height feedback used in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Model board 2 Leveling frame 3 Cast frame 5 Compression means 19 Turntable

Claims (13)

At least a model plate that is fixed horizontally when the molding sand is compressed, a leveling frame that is mounted on the model plate so as to be vertically slidable and can be moved up and down by a cylinder, and the leveling frame. A method of compressing the molding sand of a mold making space defined by a frame member disposed so as to be movable up and down above
Introducing casting sand into the mold making space;
A first compression step of compressing the beam of which a molding sand of the molding space under impossible lowered position upwardly or al compression means, - at least the leveling frame
A second compression step of further compressing the molding sand in the mold making space under the state in which the leveling frame and the frame member can be lowered;
Have a,
The rising pressure of the leveling frame that opposes the downward pressure of the compression means from above in the first compression step is held by the hydraulic pressure of the cylinder, and the hydraulic pressure of the cylinder is changed when switching to the second compression step. open leveling during compression exit frame - beam compression method casting sand upward pressure characterized by substantial without a Rukoto of. 2. The method for compressing foundry sand according to claim 1, wherein the downward squeeze pressure from above by the compression means is further increased after switching to the second compression step. 3. The method for compressing foundry sand according to claim 1, wherein the pressure for holding the frame member downward is maintained after reaching the maximum set pressure of the squeeze pressure in the first compression step . 4. After releasing the pressure for holding the frame member downward, compressing the molding sand according to claims 1 to 3, squeeze pressure in the second compression step, characterized in that it is held close to the maximum set pressure Method. In separating the mold after it is compressed pattern plate, the leveling frame - compression methods casting sand according to claims 1 to 4, the pressure of the beam is characterized in that it is initiated at substantially eliminated state. 6. The method for compressing foundry sand according to claim 5 , wherein, when the compressed mold is separated from the model plate, a pressure for holding the frame member downward is applied. The method for compressing foundry sand according to claim 6 , wherein switching from the first compression step to the second compression step is changed by a downward squeeze pressure from above by the compression means.   2. The method for compressing foundry sand according to claim 1, further comprising a step of adjusting a volume of the mold molding space before the step of introducing the foundry sand into the mold molding space. The step of adjusting the volume of the mold making space measures the mold height after the second compression process for the previous mold making, detects a difference from the target mold height, and uses a value based on the difference as a correction value. 9. The method for compressing foundry sand according to claim 8 , comprising a step of feeding back to a target value of the volume of the mold space. 10. The method for compressing foundry sand according to claim 9 , wherein the correction value is a value obtained by dividing a sand compression ratio by a difference between a mold height target value and a mold height. The method for compressing foundry sand according to any one of claims 1 to 10 , wherein the step of throwing the foundry sand into the mold making space is performed by air pressure. The method for compressing foundry sand according to any one of claims 1 to 10 , wherein the step of introducing the foundry sand into the mold making space is performed by gravity. An elevating frame constructed on a hydraulic cylinder standing on a surface plate, and a compression means disposed on the elevating frame,
In claims 1 to compression method foundry sand 12 wherein, after the second compression step, wherein the leveling frame - characterized in that it comprises a step of raising the arm at a rate above not later than the rising speed of the hydraulic cylinder Casting sand molding method.

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