JPH01113152A - Molding method for mold - Google Patents

Abstract

PURPOSE:To make a good mold at high speed by sucking and compressing casting sand to pattern plate side after floating and fluidizing sand by injecting compressed air from air vent, descending a head and compressing back face of the casting sand. CONSTITUTION:The casting sand 21 in a sand supplying hopper 18 is naturally dropped. In this time, the compressed air is injected upward from the air vent 30 arranged in the pattern plate 3. By this method, the sand is made to floated fluidizing state. Successively, the back face of the pattern plate 3 is communicated with the vacuum tank 14 to make negative pressure and the casting sand 21 is sucked and compressed into the pattern plate 3 side. Further, a squeeze head 16 and head cover 16a are descended and the back face of the casting sand 21 is pushed downward and compressed. By this method, good mold can be made under no vibration and no noize at high speed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention involves filling a casting flask placed on a perforated model plate with molding sand, and supplying compressed air from above the molding sand. The compressed air is passed through the molding sand and discharged from the hole in the model plate,
This invention relates to an improvement in the so-called static pressure molding method in which molding sand is hardened to form a mold.

[Prior Art] The above-mentioned molding method is disclosed in, for example, Japanese Patent Laid-Open No. 56-38382. In this method, a casting flask is placed on the top surface of a model plate with many small holes that communicate with the outside air, and sand particles are uniformly loosened in the space formed by the model plate and the casting flask. The method is characterized in that, at the same time, compressed air is supplied from above the molding sand to pass through the molding sand, and then the molding sand in the flask is pressed using a compression plate. This is a mold making method.

Another sand mold manufacturing method is disclosed in Japanese Patent Application Laid-Open No. 56-1405.
According to Publication No. 2, a model plate with base holes attached and a casting flask are placed on a flat surface with a plurality of pores formed on the side of a cast iron having a hollow portion formed inside, and the casting flask is A method for manufacturing a sand mold is disclosed, in which the inside of the flask is filled with molding sand, and at the same time, the internal hollow part of the suction box is set to negative pressure to airtightly fill the molding sand into the flask.

[Problems to be Solved by the Invention] The foundry sand used in this type of molding method is a normal green sand mold, contains moisture, bentonite, etc., and has caking properties. For this reason, when the foundry sand is poured into the flask, it aggregates and causes a shelf-hanging phenomenon, and the sand cannot fully penetrate into the recesses of the model plate and cavities. Granulation may occur. Therefore, in the former case, there is a problem that even if compressed air is supplied from above the molding sand, the compressed air does not flow uniformly.

In addition, in the latter molding method, as in the former, even if the molding sand in the flask is sucked in uneven conditions such as cavities and agglomerated areas, the air will not flow uniformly, so the molding sand will not be sucked uniformly. There is no problem.

For this reason, generally, when sand is introduced into a molding flask, the sand is dispersed and allowed to fall through a sieve, but it takes several seconds to fill the foundry sand in order to pass through the sieve. Another technique disclosed in Japanese Patent Application Laid-open No. 57-6445 discloses that after casting sand is put into a molding flask, a vibration generator provided on a model plate is driven to give vibration to the casting sand. Although a method for uniformly filling the material has been proposed, the advantage of vibration-free and noise-free molding, which is the most important feature of this type of static pressure molding, is lost, causing pollution and environmental problems.

In addition, the former method requires a step to compress the foundry sand by applying compressed air to the upper surface of the foundry sand, but in this step, the sand supply device that supplies the foundry sand into the molding flask is discharged from above the molding flask. After that, it is necessary to move a pressurized chamber into which compressed air is applied onto the flask, and then tightly clamp the model plate, flask, and pressurized chamber to prevent the compressed air from escaping to the outside. Compressed air is added. For this reason, there is a problem that the above steps require a considerable amount of time and effort, and the molding time is considerably long.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a mold making method that uniformly compresses and hardens foundry sand at high speed without causing vibration.

[Means for Solving the Problems] The gist of the present invention is to provide a step of filling molding sand into a molding flask combined with a model plate having a plurality of vent holes, and a step of filling the molding sand into a molding flask that is combined with a model plate having a plurality of vent holes. blowing out compressed air from the vent hole of the molding sand to make the filled molding sand into a fluid state; and applying negative pressure to the back of the model plate to suction the air in the molding sand from the vent hole of the model plate. This mold making method is characterized by comprising the steps of squeezing the molding sand onto a model plate from the upper surface of the molding sand using a sand pressing device.

[Function] As described above, in the present invention, compressed air is blown out from the vent hole of the model plate when filling the molding sand, so the molding sand becomes suspended in the flask, and the aggregated molding sand is fragmented and disintegrated into the flask. The sand grains are evenly distributed to every corner of the mold, and the height of the molding sand in the flask is evenly filled.

Moreover, since the upper surface of the sand is in a floating state, the excess molding sand thrown into the flask can be quickly discharged. By suctioning this suspended molding sand from the back of the model plate, the entire inside of the flask can be uniformly sucked, and the molding sand moves uniformly to the surface of the model plate, and the molding sand on the surface side of the model plate is removed. Densely compressed and hardened. Furthermore, by adding a squeeze to the top of the molding sand, the entire inside of the flask is evenly compressed, and a good mold that does not lose its shape is formed.

[Examples] Examples of the present invention will be described below. As shown in FIGS. 1 to 4, in the mold making machine of the present invention, a flask 1 is held on a frame feed roller 2 in FIG. It is held in the baton carrier receiver 22. Batan carrier 5
A slam lifting table 6 and a slam lifting cylinder 7 for lifting and lowering the table are arranged below. A plurality of air vents 3c are arranged on the surface of the slam plate 3, and communicate with the model 3a and the back of the slam plate 3.
Plate bins 3b provided at both ends of the slam plate 3 can be fitted with flask bushes 1a provided below the flask 1 and facing each other.

The interior 5a of the baton carrier 5 has a rib structure to properly support the baton plate 3, and is integrally hollow, with a batten carrier opening 5c and a batten carrier bush 5b provided at appropriate positions on the bottom.

On the upper surface of the slam lifting table 6 at positions facing these, a slam lifting table opening 8a and a slam lifting table pin 6b are provided, respectively. is in close contact with the slam carrier bushing lever 5b and the slam lifting table bin 8b through fitting, and the slam carrier opening 5c and the slam lifting table opening 6a communicate with each other.

On the other hand, the inside of the slam lifting table 6 is hollow, and a part of the bottom is connected to a three-way valve 9 via a hose 8. One of the other two directions of the three-way valve 9 is connected to another three-way valve 11 through a communication pipe 10, and the other side is connected to a vacuum tank 14 and a vacuum blower 15 through a communication pipe 13.

The other two directions of the three-way valve 11 are one connected to a compressed air source 12;
The other one is connected to the atmosphere opening 11a.

As a result, by selecting the positions of the three-way valve 9 and the three-way valve 11, the back surface of the slam plate 3 can be operated at either normal pressure connected to the atmosphere port tta, positive pressure connected to the compressed air source 12, or negative pressure connected to the vacuum blower 15. It can also be made into a state.

On the other hand, above the casting flask 1, a filling frame 4 is arranged so as to be vertically slidable, and above the casting flask, a sand pressing device (squeezing head) 1B is mounted on a lateral moving cart 17. The sand press provided on one side is a cylinder (skies cylinder) 16b
Furthermore, a squeeze head cover lea having an inner periphery in contact with the outer periphery of the squeezed head IB is provided on the squeezed head 1B so as to be movable up and down. The skies head cover lea is raised and lowered by a guide rod with a spring or a lifting cylinder (not shown).

A sand supply hopper 18 is fixed to the other side of the lateral moving cart, and a plurality of sand supply dampers 18b are installed at the lower part of the interior thereof.
The sand supply damper 18b is provided to be openable and closable, and the sand supply damper 18b is closed to hold the molding sand 21 in the sand supply hopper 18.
8b is opened to allow the foundry sand 21 in the sand supply hopper 18 to fall downward. A sand supply hopper cover 18a having an inner periphery in contact with the outer periphery of the sand supply hopper 18 is provided below the outside of the sand supply hopper 18 so as to be slidable up and down. The sand supply hopper force /<-18a is raised and lowered by a lifting cylinder (not shown).

The foundry sand 21 is supplied from the foundry sand supply conveyor 20 to the sand supply hopper 18 via the vibrating sieve 19.

FIG. 1 shows that when the slam cylinder 7 reaches its lowest point,
The state in which the baton carrier 5 is supported on the batten carrier receiver 22 is shown, which is normally the state at the time of model change. In a normal molding cycle, the lowering position of the drum lift cylinder 7 is controlled so that the height of the drum carrier 5 is such that it does not come into contact with the drum carrier receiver 22.

In FIG. 2, the slam lifting cylinder 7 is raised, the slam lifting table 6 is connected to the bottom surface of the drum carrier 5, and the slam plate 3 attached to the top surface of the drum carrier 5 is connected to the bottom surface of the flask 1, and the top surface of the flask 1. is in close contact with the bottom surface of the filling frame 4.

In this state, when the lateral moving cart 17 moves to the right in the figure and the sand supply hopper 18 comes to a position facing the filling frame 4, the sand supply hopper cover tga is lowered, and the sand supply damper 18b is further lowered. Open the foundry sand 2 in the sand supply hopper 18.
1 to fill the frame 4. It is allowed to naturally fall downward within the flask 1.

At this time, the three-way valve 1 is opened before, at the same time, or after a certain time when the sand supply damper 18b is opened.
1 to communicate between the compressed air source 12 and the communication pipe 10, and by causing the three-way valve 9 to communicate between the communication pipe 10 and the hose 8, compressed air pressure is introduced to the back surface of the slam plate 3, Air vent 3C installed on the slam plate 3
The compressed air is spouted upward. Thereby, the sand in the filling flask 4 and the casting flask 1 can be brought into a floating and fluid state.

Thereafter, the sand supply hopper cover 18a is raised, the sand supply damper 18b is closed, and the lateral moving cart is moved to the left.

During this time, the three-way valve 11 is operated to connect the communication pipe 10 and the atmosphere port 11a, and the back surface of the slam plate 3 is brought to normal pressure.The three-way valve 9 is then operated to connect the hose 8 to the communication pipe 13. The back side of the pattern plate 3 is connected to the vacuum tank 14 to create a negative pressure, and the filling flask 4 and the casting flask 1 are connected to each other.
The foundry sand 21 inside is suctioned and compressed toward the slam plate 3 side.

As a result, the molding sand on the slam plate 3 side is compressed more densely.

In FIG. 3, at a position where the squeezing head 16 faces the filling frame 4, the squeezing head 1B and the squeezing head cover lea are lowered to press and compress the back surface of the molding sand 21 downward.

As a result, the back side of the molding sand is compressed more densely, and the mold is formed with uniform density as a whole.

After the mold 23 is molded in the flask 1 in this way, as shown in FIG. The slam plate 3 is supported and separated from the flask 1 to be released from the mold. At this time, the three-way valve 9.11 is operated to connect the hose 8 to the compressed air source 12, and the back side of the slam plate 3 is By creating a positive pressure, compressed air is introduced between the slam plate 3 and the mold 23 via the air vent 3c, thereby preventing negative pressure during mold release and allowing smooth mold release between the mold 23 and the slam plate. be able to.

According to the molding method of this implementation, (2) When pouring the foundry sand in free fall, compressed air is ejected from the surface of the slam plate via the air vent;
The sand becomes suspended and fluid within the flask, preventing the foundry sand from agglomerating, dispersing the sand grains, and making the height of the molding sand uniform within the flask. (Uniform sand filling) (3) By setting the pressure of compressed air appropriately, 11S: ' Even in the floating and flowing state of sand, the upper part of the foundry sand is in a state of slight movement, so the sand supply device can adjust the sand feeding backward speed. It can be discharged from the top of the flask. (Reduction of molding time) (4) The sand pressing device (squeezing device) enters at the same time as the sand supply device is discharged, but by making the back of the slam plate negative pressure from normal pressure during this period, the back of the casting sand (5) After that, the sand is pressed from the back side of the molding sand by a device that moves the molding sand toward the surface of the slam plate along with gravity, improving compressibility and eliminating vibration and noise. The side far from the mold can be compressed more densely, and in combination with the above-mentioned effect (4), the mold can be compressed uniformly. (Uniform compression of the entire mold) (6) In addition, the hardening of the molding sand by suction means that there is no back surface of the molding sand, less gas is generated during pouring, and it is expected that a fume exhaust hood for pouring can be omitted. This also reduces air bubble defects such as pinholes.

(Environmental improvement, improvement in casting quality) As described above, high-speed molding of uniformly compressed molds can be achieved without vibration, and improvement in casting quality can also be expected.

[Effects of the Invention] As explained above, the mold making method of the present invention can uniformly and evenly compress the molding sand in the metal body in the flask, and can mold a good mold at high speed without vibration or noise. This is an excellent mold making method.

[Brief explanation of the drawing]

Figures 1 to 4 show examples of this explanation, Figure 1 shows the state immediately after the naepatan is handled, Figure 2 shows the state when the casting flask is filled with molding sand, and Figure 3 shows the state when the molding sand is filled in the flask. It shows the compression of molding sand by negative pressure and the compression state by squeezing, and the fourth
The figure is a sectional view showing a molded state of the released mold. l...Casting flask, 3...Bang plate. 4...Mori frame, 5...Bang carrier. 6...Bang lift table. 7...Bang lifting cylinder. 9.11... Three-way valve, 12... Compressed air source. 14... Vacuum tank, 15... Vacuum blower-916
...Skees Head, 18...Sand supply hopper. 19... Vibrating sieve, 20... Foundry sand supply conveyor. Figure 2 Figure 3

Claims (1)

[Claims] A step of filling molding sand into a molding flask combined with a model plate having a plurality of vent holes, and when filling the molding sand, blowing out compressed air from the vent hole of the model plate to displace the filled molding sand. a step of bringing the molding sand into a fluid state, a step of applying negative pressure to the back of the model plate to suck air in the molding sand from a vent hole of the model plate, and pressing the molding sand from the upper surface of the molding sand onto the model plate using a sand pressing device. A mold making method characterized by comprising a step of squeezing the top.