JPH0671640B2 - Sand mold making method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION “Object of the Invention” The present invention relates to a method for molding a sand mold, and there is a variation in the sand mold for obtaining a desired product by using an iron-based or aluminum-based molten metal or a synthetic resin solution. It is an object of the present invention to provide a method capable of accurately obtaining a molded article that is few and excellent in strength.

(Industrial application field) Sand molding technology.

(Prior Art) In obtaining a sand mold, it is necessary to closely and evenly fill a molding material formed mainly of sand into a molding area formed in a mold, and thus various conventional molding materials are required. The method has been adopted.

That is, although it is common to use a pressure method for filling the above-described shaping area, this pressure causes only concentrated compaction to be obtained at the surface portion to be pressed, and compression is performed. The acting force is squared with respect to the distance from the pressing surface due to the resistance of the charged molding material, and the pressing force hardly reaches the inside or the opposite surface of the filling molding material, and it remains just charged. Maintain a state close to. Therefore, it is required to apply the pressure (squeeze) together with a filling effect such as an impact vibration action in addition to the pressure application. As such impact vibration, an anvil jolt (a jolt table on which a mold is mounted is used). Combined use of shock vibration when it is raised and then lowered by its own weight to collide with the support) and ram jolt (which uses shock vibration caused by ram colliding a ram operated by fluid pressure against the jolt table) However, the inventors of the present invention have been able to obtain the effects of both the anvil jolt, which has a large tendency to make the filling state uniform even if the impact is the same, and the strong effect of lamb jolt, which has a strong tendency to make the filling state dense. -17984 has been developed and is gaining popularity in the industry for its advantages.

(Problems to be Solved by the Invention) Although the technology developed by the inventors of the present invention as described above is quite effective, as a result of conducting many years of practical studies on such technology, the workability thereof is improved. Needless to say, it is preferable to further increase the degree of compression or densification.

[Structure of the Invention] (Means for Solving Problems) A master plate having a pattern is interposed between an upper mold and a lower mold, and a molding material mainly composed of sand is provided in the upper and lower molds. When the molding material is clamped between the squeeze head and the jolt table, and the pressing force by the squeeze head and the impact force by the jolt table are simultaneously applied for compaction, the upper and lower molds are gripped by the clamping means. Then, the clamp means is retracted after being set on the jolt table, and further, the squeeze head provided on the squeeze table is lowered together with the squeeze table, and the upper and lower molds and the squeeze head are combined by the die leveling means provided on the squeeze table. A sand-molding method, characterized in that the above-mentioned compaction is performed after adjusting the level between them.

(Operation) After the upper and lower molds are set on the jolt table by the clamp means, the clamp means is retracted, and the squeeze head provided on the squeeze table is lowered and pressed down to form the mold between the jolt table and the squeeze head. The inner molding material is clamped under conditions avoiding the constraint of the clamping means.

When the squeeze head is pressed down, the leveling and parallelism between the mold and the squeeze head (squeeze table) are accurately adjusted by the mold leveling means provided on the squeeze table.

The pressing means by the squeeze head and the impact force by the jolt table are retracted from the clamp means as described above,
Under the condition that the mold part is completely separated from the frame, they are allowed to work together to perform efficient compaction with less vibration and noise.

In the compaction, a preferable compaction action can be obtained by initially applying a reduction for a relatively short time only by the squeeze head, and then also applying an impact force by the jolt table under the pressurizing condition of the squeeze head.

The initial reduction by only the squeeze head is preferably a relatively short time corresponding to about 10 to 30% of the total compaction processing time. That is, if it is less than 10%, the effect due to the reduction of the squeeze head is poor, and if the reduction of the squeeze head is more than 30%, the portion joined to the squeeze head is preferentially compacted, and the subsequent compaction is generally performed. There is still a tendency that it cannot be obtained evenly.

As described above, in the initial stage, the rolling operation is performed only by the squeeze head for a relatively short time, and the subsequent simultaneous operation of the squeeze of the squeeze head and the impact action by the jolt table adopts a hydraulic or hydraulic mechanism for the squeeze head. Regarding the operation of the table, it is preferable to adopt an air pressure operation mechanism.

That is, even if the operations are started at the same time by adopting the hydraulic pressure or the hydraulic pressure and the pneumatic pressure in this way, the squeeze head is immediately activated by the hydraulic pressure or the hydraulic pressure. It is possible to realize the operation relationship due to the time difference as described above without causing a particularly complicated start operation because of a time delay for increasing the pressure.

(Examples) To further explain the present invention, the inventors of the present invention conducted a field study on many concrete molding equipments and molding methods according to the prior art by the inventors of the present invention as described above, and as a result, The casting (pattern) to be finally obtained by using a sand mold etc. at the time of molding is prepared by attaching the pattern to a supporting plate (master plate), and inserting it between the upper and lower molds. I often do
Further, in order to apply both the squeeze and the jolt treatment as described above under effective treatment conditions, these treatment means should be arranged vertically, and therefore the above-mentioned upper and lower molds should be arranged vertically. If the upper and lower molds are supported by a machine frame or the like, the Jolt effect will be very poor. That is, the formwork should be in a floating state with no support structure,
Moreover, such unsupported molds have a marked tendency to deviate and incline under the condition of processing by impact force, and the deviation of the molds also deviates the tightness of the granular molding material, resulting in an inferior molded product. A uniform tightened state is achieved.

In the present invention, as described above, many studies and speculations have been made on overcoming any of the difficult technical conditions,
Moreover, it succeeded in obtaining an effective sand mold precisely by adopting a special method that efficiently exerts the mold clamping effect under the combined condition of the squishy action and the jolt action. That is, first, one example of equipment manufactured to be suitable for specifically carrying out the method of the present invention will be described with reference to the embodiment shown in the accompanying drawings. The general structural relationship is as shown in FIGS. And the columns 21,2 on both sides of the machine base 20.
1, 22, 22 are provided, an upper arm 23 composed of arm portions 23a and 23b protruding in the front-rear direction is attached to the upper ends of the columns 21, 21, and a rear arm portion 23b is attached to the columns 22, 22. There is. Further, the pressing cylinder 2 is provided on the side surface of the front protruding arm portion 23a.
The support arm 25 of 4 is pivotally attached to the vertical axis 26, and the operation arm 17 fixed to the vertical axis 26 is connected to a piston rod 59 of a swing cylinder 58 whose base end is pivotally supported outside the arm portion 23b. ing. Further, squeeze table guide rails 35 are provided inside the respective arm portions 23a and 23b, and a squeeze table 40 is mounted on the squeeze table guide rails 35 and 35 by a trouser 32. A moving operation cylinder 33 is provided at the rear portion of the table 40, and the squeeze table 34 is operated to move in the front-back direction (left-right direction in FIG. 1). On the front side of the machine base 20, there is provided a jolt cylinder 6 which performs an impact operation as shown in FIGS. 1 and 2, and the jolt table 2 is mounted on the jolt cylinder 6. . The internal structure of the jolt cylinder 6 and the operation of the jolt table 2 by the jolt cylinder 6 are as described in detail in the above Japanese Patent Publication No. 56-17984, and in short, the anvil jolt described above. Alternatively, either one or both of the Ramjolts can be obtained in combination, and the impact operation can be performed on the upper and lower molds 11 and 12 placed on the jolt table 2 and the molding material charged in the molds 11 and 12. To give.

A shuttle guide 81 is provided on a receiving seat 82 at the rear of the machine base 20 and engages with an engaging portion 84 of the shuttle frame 8.
The shuttle operation motor 83 moves and operates the shuttle frame 8 in the front-rear direction (left-right direction in FIG. 1), and the master plate receiving pins 85 are arranged on the front and rear of the shuttle frame 8, respectively. The master plate 9 which is interposed between the mold 12 and the mold 12 is received and moved.

The upper mold frame 11, the lower mold frame 12, and the master plate 9 described above are set on the jolt table 2 as shown in FIGS. 1 and 2, and the upper mold frame 11 and the lower mold frame 12 are made of aluminum. As shown in FIGS. 3 to 5, separately, the projecting seats 52 on both sides of the lower mold 12 are provided with guide pins 15 for frame matching so that the upper mold 11 can be engaged with the upper mold 11. It is designed to be inserted into and removed from the dowel, and both of these formwork 11, 12
A protrusion 51 is appropriately formed on the
a, 11b and 12a are provided.

A lift arm 5 which is the main part of the die-cutting mechanism is provided in the middle of the machine base 20, and the machine base 20 is provided in the center of the lift arm 5.
The lift cylinder 41 provided at the upper end of the lift arm 5 acts on the lift arm 5 and the clamp bases 3 are oppositely provided on both ends of the lift arm 5. These clamp bases 3 are for gripping the upper mold 11 and the lower mold 12 as described above and performing an inversion operation together with an inversion mechanism described later.

As shown in FIG. 2, sliding cylinders 50 are provided on both sides of the lift arm 5.
Is provided, and the lift arm 5 is guided up and down by the sliding cylinder 50 by engaging the above-mentioned supporting column 22 in the sliding cylinder 50, that is, by extending and contracting the lift cylinder 41 using the supporting column 22 as a guide. The above-mentioned upper mold 11 is attached to the clamp base 3 as described above.
There are provided four upper frame removing pins 31 and four plate removing pins 39 for removing the master plate 9 (two for each of the clamp bases 3 on both sides), and each clamp base 3 is respectively A slide seat 30 is provided via two slide cylinders 34, 34, that is, the slide seat 30 is a clamp base 3
It is provided so as to move in the left-right direction in FIG. 2 along a guide 44 as shown in FIG. 1 above by the action of one or both of the cylinders 34, 34. Further, such a slide seat 30 is provided with the reversing head 4 as shown in FIG. 2, and the reversing head 4 is rotatably supported by the clamp head 37. Clamp cylinder 3 to operate the removal pins 31, 39 like
8 and 38 are vertically opposed, and the slide seat 30 has the first
A reversing motor 42 is provided as shown in the figure
The interlocking system 43 by 42 rotates the clamp head 37 supported by the reversing head 4.

The squeeze cylinder 40 is provided on the squeeze table 40 described above, and the squeeze head 13 is attached to the rod 19 which acts downward. The guide bars are provided on both sides of the squeeze head 13 as shown in FIG. 27 are arranged opposite to each other, and these guide bars 27 are guide tubes provided on the squeeze table 40.
It is inserted in 29 to guide the pressing action of the squeeze head 13. Further, two frame leveling pins 28 are arranged on both sides of the squeeze table 40, and the frame 11 or the frame 11 is raised by the operation of the lift arm 5 as described above.
Joined on both sides of 12 to obtain proper frame leveling, orthogonal to the pressing direction of the squeeze head 13, and the jolt table 2
It is configured to have a parallel relationship with.

The master plate 9 already described has a pattern in its central portion.
It is well known that the 60 is mounted, and the pattern 60 is held in the inner cavities of both molds 11 and 12 by being interposed between the upper mold 11 and the lower mold 12, as shown in FIG. To be done. Both formwork
As shown in FIG. 4, the reference numerals 11 and 12 form the above-mentioned cavity with the molding surfaces 111 and 121 that have an appropriate taper for die cutting. The surface plate 45 is accommodated and set in the frame 12 as shown in FIG.
A squeeze or jolt action is given via. That is, as described above, a granular molding material containing a mixture of a condensing material such as sand and bentonite is charged under the condition that both molds 11 and 12 are properly leveled by the frame leveling pins 28, 28, 28, 28. The tightening operation is performed under the leveling holding condition.

The squeeze cylinder 18, the jolt operation mechanism in the jolt cylinder 6, the slide cylinder 14, the clamp cylinder 16, the swing cylinder 19, the operation cylinder 2
It is obvious that an appropriate gas or liquid can be adopted as the operating fluid for the moving operation cylinder 33, the slide cylinder 34, the clamp cylinder 38, and the lift cylinder 41. However, according to the results of the concrete examination conducted by the present inventors, regarding the compaction according to the present invention as described above, a relatively slight reduction is applied for a short time at the start, and then a full-scale compaction operation is performed. It is possible to obtain preferable results by carrying out. For such compaction in the initial short time, it is sufficient to use only a squeeze head, and in order to realize compaction operation with such a time difference, the squeeze cylinder 18 is provided with a liquid such as a hydraulic pressure. It is advantageous to adopt pressure and to adopt air as the working fluid for obtaining the impact operation in the jolt cylinder 6. That is, the air as the working fluid in the jolt cylinder 6 has a certain time delay in order to obtain a predetermined working pressure, but in the case of hydraulic pressure such as hydraulic pressure, there is no such time delay, so start at the same time. Also, the impact operation in the jolt table is delayed, and the preferable compaction operation relationship with the above-mentioned time difference can be automatically realized.

It is practically preferable that the lift cylinder 41 is also a hydraulic cylinder.

As the casting sand for obtaining the sand mold, silica sand, zircon sand, olivine sand, sillimanite, sheamot, etc. are adopted as refractory particles, and organic or clay as a binder, or an inorganic substance such as water glass is mixed, Furthermore, it is well known that wood powder, coke powder, coal powder, etc. and water are used as auxiliary additives, but in the case of the present invention, the water content required in such a molding raw material is 4% or less. It is preferable that it is relatively small.

To explain the operation of the present invention as described above, as shown in FIGS. 1 and 2, the lower mold 12 is set upward and both molds 11 and 12 are set in the equipment of the present invention. The lower mold is a granular molding material such as a feeder that contains appropriate moisture and contains a coagulating material such as bentonite.
As shown in Fig. 6 (a), a jolt operation is performed by operating the jolt cylinder 6 for a predetermined time as shown in Fig. 6 (a). At this time, the granular molding material is additionally charged depending on the filling condition and the surface is flattened. Place the surface plate 45 as. Once prepared in this way, the clamp base 3 is fully advanced by both slide cylinders 34, 34 as shown in FIG.
The surface plate 45 and the upper frame 11 are clamped at a part, and then the reversing motor 42 is also operated while raising the lift arm 5.
Clamping head with inversion heads 4 and 4 for both molds 11 and 12
Rotate 180 ° at 37 shaft support. In this case, after the above clamping, the lift arm 5 is stopped at the intermediate position as shown in FIG.
Rotation of the clamp head 37
Then, the clamp base 3 is moved back to the outermost position as shown in FIG. 6 (c), and both the molds 11 and 12 are placed on the jolt table 2 with the surface plate 45 still attached, and brought into an unclamped state. .

In the state of FIG. 6 (c), the molding material such as sand is charged on the master plate 9 in the upper mold 11, and the surface is made flat as in the case of the lower mold 12, and then the squeeze cylinder 18
And press inside the upper frame 11 with the squeeze head 13,
In the state of FIG. 6 (d), the jolt table 2 is raised, both molds 11 and 12 are held at the intermediate position of the frame, and the proper leveling positions are taken by the frame leveling pins 28 and 28 for molding. A molding process by pressure and shock vibration is applied. In this pressurization and impact vibration, from the results of many practical studies by the present inventors, in the present invention, the pressurization by the squeeze cylinder 18 is 50 to 70% of the target pressurizing force in the preceding stage of the molding process. The molding process is performed under the restricted pressurizing condition for a predetermined time, and then the molding process is performed by applying a target pressure of 100%.

After performing the molding process (pressurization and impact vibration) for a predetermined time in the state of FIG. 6 (d), the molding process is stopped and the squeeze head 13 is raised, and the clamp base 3 and the clamp head 37 are used. Is moved to an intermediate position by operating only one cylinder 34, and the master plate 9 is received by the pin 31 portion and the lift arm 5 is fully extended to the lift cylinder 41 as shown in FIG. 7 (a). Then, the projecting portion 51 of the upper mold 11 is received by the pin 39, and the lift arm 5 is raised to perform the die cutting while imparting shock vibration, and the upper mold 11 is raised and the lower mold 12 is lowered. Then, the shuttle frame 8 is advanced to the molding position, and together with this, the clamp base 3 and the clamp head 37 are retracted to the unclamped state, whereby the master plate 9 is moved to the shuttle frame. When the shuttle frame 8 is moved backward, the master plate 9
And the pattern 60 is withdrawn from the molding position. It is apparent that the master plate 9 and the pattern 60 can be easily separated from the molding sand molds of both molds 11 and 12 by the impact vibration.

After the master plate 9 is removed as shown in FIG. 7 (a), the swing cylinder 19 acts on the operation cylinder 24 provided on the front side of the arm 23 as shown in FIG. 7 (b). Position them above both molds 11 and 12, then lower the piston rod of the operating cylinder 24 as shown in FIG. 7 (c), and lift arm 5 as shown in FIG. 7 (d). The sand mold 55 that has been raised and molded together with the molds 11 and 12 is left on the jolt table 2 together with the surface plate 45, and the molds 11 and 12 are demolded.
When the state of FIG. 7 (d) is reached, it is clear that the sand mold 55 can be taken out from the jolt table 2 by an appropriate means, that is, the manual work together with the surface plate 45 is generally sufficient.

In the state shown in FIG. 7 (d), the slide cylinder 3
Only one of the pistons 4 and 34 is extended, but when both cylinders 34 and 34 are retracted from the state of Fig. 7 (d) to the state of Fig. 8 (a), Only the locking of the pin 31 to the mold 12 is released, and the upper mold by the pin 39
The support points of 11 are moved to the outside, and the lower mold 12 is placed on the jolt table 2, and only the upper mold 11 is sufficiently lifted by the lift arm 5 being lifted. That is, since the space between the two molds 11 and 12 is greatly opened, the shuttle 8 enters between the molds 11 and 12 while supporting the master plate 9 and the pattern 60, and both sides of the master plate 9 are pin 39. The shuttle 8 moves backward in the half clamped state supported by the.

As described above, the master plate 9 is positioned between the molds 11 and 12, and the lift arm 5 is lowered, so that the master plate 9 is positioned on the jolt table 2 as shown in FIG. 8 (b). The upper frame 11 is set on the lower mold 12 and the upper frame 11 is also positioned on the master plate 9. Further, in this state, the slide cylinder 34 pushes the slide seat 30 inward, so that the molds 11 and 12 having the master plate interposed therebetween are clamped by the pins 31 and 39.

If the two molds 11 and 12 are not clamped in a protruding state as described above, the lift arm 5 is lifted and the molds 11 and 12 are separated from the jolt table 2 as shown in FIG. 8 (c). In the disengaged state, the reversing head is operated to reverse both molds 11 and 12, and then the unclamped state, and then the lift arm 5
Is lowered to place the upper and lower molds 11 and 12 on the jolt table 2, then the lift arm 5 is raised to the middle and lower stages, and the slide seat 30 is moved to the outer side, whereby the state shown in FIG. After returning to the state of FIG. 6 (a), the next molding operation can be repeated in the same manner as described above.

Explaining an operation example using the above-mentioned equipment,
It is as follows.

The third to fifth vertical formwork pattern 60 of about 5000 cm ² between like view is formed as a molded area of about 50000 cm ² should accommodate molding material is set by the platen 45, Fuchaku the upper and lower mold within A molding material prepared by mixing about 3 wt% of bentonite with silica sand as a casting sand having a water content of 3.5% was charged.
Molding was performed according to the steps shown in FIG. That is, the lower mold and the upper mold are respectively filled with the molding material and flattened, and then the jolt table 2 which is operated by air pressure and the squeeze head 13 which is operated by hydraulic pressure are used to press and hold the upper and lower molds and the molding material from above and below to clamp. The heads 37, 37 are sufficiently retracted together by the operation of the slide cylinder 34, and the molds 11, 12 or the platen 45 are completely separated from the frame, and molding is performed under the condition of being supported only by the table 2 and the head 13. When clamping the mold, a pressure is applied by applying only the pressing force by the hydraulic pressure of the squeeze head 13 for about 1 second. Following this initial reduction, a hydraulic pressure reduction force of about 5 tons is applied, and the amplitude is about 30 mm. A target sand mold was obtained by a compaction treatment for about 5 seconds by applying a ramjolt of 12 hertz. The hardness of each part of the obtained sand mold was measured by a sand hardness meter, and the result was 92 ° (91 to 94 °) on average, and it was confirmed that the sand mold was excellent.

On the other hand, as a comparative example, using the equipment described in Japanese Patent Publication No. 56-17984, the same molding sand and bentonite as those described above are also charged, and molding and mold clamping are performed. The hardness of the obtained sand mold was considerably lower than that described above, that is, it was 80 ° or less on the sand mold hardness meter, and the variation in each part remained to some extent.

"Effects of the Invention" The following effects can be obtained by the present invention as described above.

I. A sand mold with high hardness and less variation can be obtained.

According to the present invention as described above, the pressing or impact force of the squeeze head and the jolt table is simultaneously acted on the filling material in the mold, and particularly, the initial squeezing force is applied only after the initial process of the pressing by only the squeeze force. It is possible to perform compaction, and it is possible to obtain a sand mold having a sufficiently high hardness and a hardness distribution with little variation.

II. Vibration noise is small due to the jolt action force for compaction.

According to the present invention, when the mold or master plate is completely separated from the frame, the jolt force acts on the molding material in the mold together with the squeeze force. Since it is rarely propagated to a support deck or the like, it is possible to perform an operation in which vibration noise is relatively small.

III. Accurate molding or demolding.

In the present invention, the mold is operated in a suspended state in which it is completely separated from the frame, etc., but during the molding, the mold always forms an appropriate level by the frame leveling means arranged on the squeeze table. Since it can be maintained, both the squeeze force and the jolt force properly act on the molding material in the mold, and the mold clamping is not biased and variations are less likely to occur. Further, in this way, the molded product that is properly compacted with respect to the mold and has no unevenness or variation can be smoothly and accurately released from the mold.

IV. The working energy for molding is small.

Since the present invention as described above enables efficient molding, a small amount of energy for molding is sufficient. Especially, it is very advantageous because the energy that is propagated and lost to the foundation through the frame becomes extremely small.For example, the squeeze pressure used in the present invention is simpler than the conventional one that is simply formed by pressing force. In general, a very small one-third or less is sufficient.

It should be noted that the fact that such a small amount of energy is sufficient is energy consuming and also causes a reduction in the above-mentioned noise generation.

[Brief description of drawings]

The drawings show the technical contents of the present invention. FIG. 1 is a side view of an example of equipment for carrying out the method of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a mold thereof. In a plan view of one example of the frame, one half shows an upper mold part and the other half shows a lower mold part. FIG. 4 is a sectional view thereof, FIG. 5 is a side view thereof, and FIGS. FIG. 6 is a step-by-step view of the molding operation relationship of the present invention. FIG. 6 is a sand pour to squeeze and compaction process by jolt on the mold, and FIG. 7 is a process of taking out the sand mold after the master plate is removed. FIG. 8 is a step-by-step diagram showing the process of connecting the master plate from the subsequent charging of the master plate, reversing it, and proceeding to the next molding operation. However, in these drawings, 1 is a squeeze plate,
2 is a jolt table, 3 is a clamp base, 4 is a reversing head, 5 is a lift arm, 6 is a jolt cylinder, 7 is a clamp head, 8 is a shuttle frame, 9 is a master plate, 10 is a shuttle frame, and 11 is an upper formwork. , 11a and 11b are the dowel holes, 12 is the lower formwork, 12a is the dowel hole, 13 is a squeeze head, 14 is a slide cylinder, 15 is a guide pin,
16 is a clamp cylinder, 17 is an operating arm, 18 is a squeeze cylinder, 19 is a swing cylinder, 20 is a machine base, 21, 22
Is a pillar, 23 is an upper arm, 24 is an operating cylinder, 25 is a support arm, 26 is a slide rail, 27 is a guide bar, 28 is a frame leveling pin, 29 is a guide tube, 30 is a slide seat, and 31 is an upper frame die-cut. Pin, 32 is trochanter, 33 is a moving operation cylinder, 34
Is a slide cylinder, 35 is a squeeze table guide rail,
37 is a clamp head, 38 is a clamp cylinder, 39 is a master plate removing pin, 40 is a squeeze table, 41 is a lift cylinder, 42 is a reversing motor, 43 is its interlocking system, 44 is a guide, 45 is a surface plate, and 50 is a slide. Moving cylinder, 51 is a protruding portion, 52 is a protruding seat portion, 55 is a molded sand mold, 81 is a shuttle guide, 82 is a seat, 83 is a shuttle operation motor, 84 is an engaging portion, and 85 is a master plate receiving pin. It is shown.

Claims (4)

[Claims] 1. A master plate having a pattern is interposed between an upper mold and a lower mold, and a molding material mainly composed of sand is charged into the upper and lower molds and a squeeze head and a jolt table are provided. When the molding material is held between the two, and the pressing force by the squeeze head and the impact force by the jolt table are simultaneously applied for compaction, the upper and lower molds are gripped by the clamp means and set on the jolt table, The clamping means is retracted, the squeeze head provided on the squeeze table is lowered together with the squeeze table, and the level between the upper and lower molds and the squeeze head is adjusted by the die leveling means provided on the squeeze table, and then the above-mentioned tightening is performed. A sand-molding method characterized by hardening. 2. The mold leveling means adjusts the level between the mold and the squeeze head, and then the rolling is performed only by the squeeze head, and then the impact force by the jolt table is also applied under the action of the rolling down force of the squeeze head. The method of molding a sand mold according to claim 1, wherein the sand molds are made to act simultaneously. 3. The method for molding a sand mold according to claim 2, wherein the reduction by only the squeeze head after the level adjustment is performed for a short time of about 0.5 to 2 seconds. 4. The method for molding a sand mold according to claim 1, wherein the reduction applied to the squeeze head is performed by hydraulic pressure, and the impact operation on the jolt table is performed by pneumatic pressure.