JPS636305B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold making method suitable for molding a main mold using a split mold using molding sand containing a gas-curing binder.

Generally, in gas-curing mold making methods such as the cold box method and the SO ₂ method, which use harmful gases to create molds, gas leaks are a problem because the harmful gases harm the human body and emit bad odors. It is necessary to have an airtight structure to prevent However, this has various problems, such as a large-scale and complicated structure, and in addition, it is difficult to handle. and,
It was difficult to mold the main mold using a split model using this type of method.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a mold making method that does not cause gas leakage and can easily make a main mold using a split model. The configuration and operation of the present invention will be explained below based on the embodiments shown in FIGS. 1 and 2. Reference numeral 1 denotes a model stand that is equipped with a decompression chamber 2 inside and a plurality of ventilation holes 3 at appropriate locations on the top surface communicating with the decompression chamber 2. On the top surface of the model table 1, a lower frame 4 is shown. The lower model part 5 of the split model provided with a pin hole 5a is placed approximately in the center of the model stand 1. In the space defined by the model stand 1, the lower model part 5, and the lower frame 4, molding sand 6 containing a gas-curing binder is placed on approximately the same level as the upper surface of the lower frame 4. It has been filled. In addition,
A vent plug 7 is embedded in the vent hole 3 to prevent the foundry sand 6 from being discharged. Reference numeral 8 denotes a cover member having a recess 9 on the lower surface and a gas supply hole 10 formed in the center thereof, and the cover member 8 is placed on the upper surface of the lower frame 4. An inverted U-shaped cap 13 is placed in communication with the gas supply hole 10 and is connected to the gas generator 11 via a flexible conduit 12 . In the state shown in FIG. is sucked into the lower frame 4 through the flexible conduit 12, the cap 13, and the gas supply hole 10 by creating a negative pressure in the lower frame 4, passes through the molding sand 6, and is discharged from the ventilation hole 3. At this time, the molding sand 6 in the lower frame 4 is hardened by contact with the hardening gas. On the other hand, the curing gas discharged from the vent 3 is collected and removed via the decompression chamber 2 and the conduit 14 to a deodorizing device (not shown). In this way, after the molding sand 6 in the lower frame 4 is hardened by passing the hardening gas for a predetermined period of time and the molding is completed, the cap 13
is removed, and the curing gas remaining in the lower frame 4 is removed by operating a vacuum pump (not shown). Thereafter, the cover member 8 as shown in FIG.
is removed, the lower frame 4 containing the molded lower mold is turned over onto the upper surface of the model stand 1, and the remaining upper mold part 15 of the split model with the pin 15a attached is placed on the upper surface of the lower mold part 5. Next, the pins 15a are fitted into the pin holes 5a and set, and the upper frame 16 is superposed on the lower frame 4, and then a release agent is applied to the sand surface of the lower mold and the surface of the upper mold part 15. After filling the upper frame 16 with gas-curable molding sand 17 on the same level as the upper surface of the upper frame 16, the cover member 8 is placed on the upper surface of the upper frame 16, and the upper surface of the cover member 8 is ,
A cap 13 is placed in communication with the gas supply hole 10 (FIG. 2), and then a vacuum pump (not shown) is connected to the conduit 14 in the same manner as in the molding operation of the lower mold in FIG. ), the curing gas stored in the gas generator 11 is sucked into the upper frame 16, passed through the molding sand 17, 6 in the upper and lower frames 16, 4, and then The molding sand 17 inside is hardened. In this way, after the molding sand 17 in the upper frame 16 is hardened and molded by aeration of hardening gas for a predetermined period of time, the cap 13 is removed and the vacuum pump (not shown) is operated to remove the frames 4 and 16. The hardening gas remaining in the upper frame 16 is collected and removed via a conduit 14 to a deodorizing device (not shown), and the molding sand in the upper frame 16 is hardened and molded. After that, the cover member 8 is removed, the lower frame 4 and the upper frame 16 are disengaged, and the upper frame 4 and the upper frame 16 are disengaged.
Upper and lower model parts 5 and 15 from the lower mold, respectively.
After cutting out the upper and lower molds, the upper and lower frames 4 and 16 are brought together again, and the cut out upper and lower molds are brought together to form a completed mold.

In FIGS. 3 to 5, which will be described below, the same components as those in FIGS. 1 and 2 are designated by the same numbers, and the explanation thereof will be omitted. Instead of the cap 13, a flexible conduit 1 is attached at one end, as shown in FIG.
The nozzle 18 , which is connected to the gas generator 11 through the gas supply hole 2 , is penetrated and inserted into the gas supply hole 10 to form the recess 9 .
You can also make it look inward. 19 is a sealing member. In addition, the model stand 1, the lower frame 4, and the upper
If there is air leakage at the mating surfaces of the lower frames 4, 16 and the upper frame 16 and the cover member 8, and the suction effect is poor, cover them with a flexible film sheet 20 as shown in FIG. Also good. Reference numeral 21 denotes a hole provided in the film sheet 20 so as to communicate with the gas supply hole 10. The film sheet 20 is brought into close contact with the periphery of the frame from the state shown by the dashed line to the state shown by the solid line due to the suction action from the frame mating surfaces and the like. In addition, if the model is complex and it is difficult for the curing gas to reach every corner of the model,
As shown in FIG. 5, a plurality of gas supply holes 23 are provided in the cover member 22, and one end is connected to the gas supply hole 23 on the upper surface of the cover member 22, and one end is connected to the gas generator 11 through a flexible conduit 12 and a branch pipe 24. Caps 25 connected to each other may be placed respectively. Of course, models of runners, sprues, etc. are also included in the category of split models. In short, the present invention includes a lower frame and a lower model section placed on the upper surface of a model table which has a decompression chamber inside and a plurality of ventilation holes communicating with the decompression chamber on the upper surface, and the model table. The space defined by the lower mold part and the lower frame is filled with molding sand containing a gas-hardening binder, and the upper surface of the lower frame is covered with a cover member provided with a gas supply hole. Then, a gas generator is connected to the gas supply hole, a suction device connected to the decompression chamber is operated to create a negative pressure in the lower frame, and the hardening gas in the gas generator is transferred to the gas supply hole. The molding sand in the lower frame is sucked into the lower frame through the molding sand, etc., and is passed through the molding sand to harden the molding sand in the lower frame.Then, the cover member on the upper surface of the lower frame is removed, and the lower frame containing the formed lower mold is removed. Above
The bottom is reversed and replaced with the top surface of the model stand, and then the upper model section is molded onto the back (top surface) of the lower model section, and the upper frame is superimposed on the inverted lower frame. , the space defined by the lower mold, the upper mold part, and the upper frame is filled with molding sand containing a gas-hardening binder, and the upper surface of the upper frame is provided with gas supply holes. After covering with a cover member, a gas generator is connected to the gas supply hole, and a suction device connected to the decompression chamber is operated to create a negative pressure in the upper frame through the lower frame etc., thereby discharging the gas. The hardening gas in the generator is sucked into the upper frame through the gas supply hole, etc., and passed through the molding sand in the upper frame and the lower frame to harden the molding sand in the upper frame, and in the same way. Since we adopted a method of hardening the entire molding sand inside the upper and lower frames,
It is a simple device with no gas leakage, allows the main mold to be formed using a split model, and has excellent effects such as a secure working environment, and the effects it brings to this type of industry are significant.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing an embodiment of the present invention, and FIGS. 3 to 5 are cross-sectional views showing other embodiments of the present invention. 1...Model stand, 2...Decompression chamber, 3...Vent hole,
4... Lower frame, 5... Lower model part, 8, 22... Cover member, 10, 23... Gas supply hole, 11...
Gas generator, 15...Upper model section, 16...Upper frame.

Claims (1)

[Claims] 1. A step of placing a lower frame and a lower model part on the upper surface of a model table which is equipped with a decompression chamber inside and has a plurality of ventilation holes communicating with the decompression chamber on the upper surface; Filling the space defined by the mold part and the lower frame with molding sand containing a gas-hardening binder, and then covering the upper surface of the lower frame with a cover member having a gas supply hole. , a gas generator is connected in communication with the gas supply hole, a suction device connected in communication with the decompression chamber is operated to create a negative pressure in the lower frame, and the hardening gas in the gas generation device is transferred to the gas supply hole, etc. A process of sucking into the lower frame through the molding sand and hardening the molding sand in the lower frame by passing it through the molding sand, and removing the cover member on the upper surface of the lower frame to remove the molding agent from the lower frame containing the lower mold. The process of reversing the top and bottom and replacing it with the top surface of the model stand, and the back (top surface) of the lower model part
A step of mold matching the upper mold part and superimposing the upper mold part on the inverted lower mold part, and injecting gas into the space defined by the lower mold part, the upper mold part, and the upper mold part. a step of filling molding sand containing a curable binder and covering the upper surface of the upper frame with a cover member having a gas supply hole; and connecting a gas generator to the gas supply hole, which communicates with the decompression chamber. The connected suction device is operated to create a negative pressure in the upper frame through the lower frame, etc., and the curing gas in the gas generator is sucked into the upper frame through the gas supply hole, etc. A mold making method comprising the step of hardening the molding sand in the upper frame by passing it through the molding sand in the frame and the lower frame.