JPH04157043A - Method and apparatus for molding mold - Google Patents

Abstract

PURPOSE:To obtain a precise mold without any deformation by fitting low friction member to inner wall face, shifting into a flask after packing molding sand in an auxiliary flask having size of interval between walls smaller than size of interval between walls of the flask and fixing the molding sand to the flask with an upper peripheral segment. CONSTITUTION:On a lower pressurizing segment 24', a molding board 27 and a side mold 22 are mounted. The upper segment 24 which can receive/pressurize the molding sand 21 independently and arbitrarily according to the shape of the side mold 22 is arranged. Then, the low friction member 11 is fitted on the inner wall face of auxiliary flask 20. The size of interval between the walls of auxiliary flask 20 is a little smaller than the size of interval between the walls of flask, and after packing the molding sand 21 in the auxiliary flask 20, this is shifted in the flask 23 and the molding sand 21 is fixed to the flask 23 with the upper peripheral segment 24. By this method, internal stress to be cause of deformation of the mold can be relieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a molding method and apparatus capable of molding a highly accurate mold with a uniform filling degree and little deformation.

[Conventional technology]

Normally, sand molds are molded into molds during molding for transportation, mold matching, etc. in the post-molding process. At this time, the inner wall surface of the formwork is made into a rough surface similar to the skin of a casting, or tapered upward and downward in order to improve the integrity of the mold with the sand mold and prevent the sand mold from falling or shifting during handling in the subsequent process. Measures are being taken to:

Conventionally, the molding method is as shown in Figure 6.
The molding was performed by pressurizing the molding sand 1 with the upper segment 4 from the upper part of the mold (on the opposite side of the model 20). For this reason, due to the transfer loss of the pressurizing force in the molding sand 1, the upper pressurizing force was not entirely transmitted to the surface of the model 2, and the degree of filling of the molding sand 1 was lowered. is formwork 3
The pressing force was reduced due to friction between the inner wall surface and the molding sand 1, and the degree of filling was lower than in the center of the mold.

Furthermore, as a method for efficiently pressurizing the filling of the molding sand 1, a method is disclosed in Japanese Patent Publication No. 59-27266 in which the mold is pressurized from both the upper and lower sides by the upper segment 4A and the lower segment 4B, as shown in FIG. ing. With this method, some improvement was seen in making the filling degree inside the mold uniform and improving the filling degree on the two sides of the model compared to the method shown in Figure 6, but the mold 3A
The decrease in the degree of filling caused by friction between the inner wall surface and the foundry sand IA could not be improved. Currently, in order to compensate for this drawback, there is a method of increasing the overall pressing force and further increasing the pressing force of the peripheral part by dividing the pressing force of the upper segment 4 as shown in Figs. As shown in the figure, a method of applying vibration to the jort mechanism 6 has been adopted, but there is a problem with noise.In recent years, as shown in Figure 8, the degree of filling has decreased due to friction between the molding sand and the inner wall surface of the mold. Inner wall surface of formwork 3B and molding sand IB
A small air blowing hole F is provided in the inner wall surface of the formwork 3B for the purpose of flowing air to form a thin air layer 8 between the model surface plate 7', and air is sucked through the small hole F' in the periphery of the model surface plate 7'. JP-A-58-125331 discloses a method of molding a mold by pressurizing foundry sand IB with upper and lower segments 4C and 4D. As mentioned above, the inner wall surface of the mold is roughened or squared to increase friction in order to strengthen the integration with the molding sand, and even if the molding sand IB itself is filled to a large extent, it does not allow ventilation. Therefore, it was difficult to selectively form an air layer throughout the filling process over the entire contact surface, and as a result, the effect of reducing frictional force was small.

In any of the methods shown in Figures 6 to 8, the pressure applied during filling remains in the molding sand as a compressive force, and when the upper and lower pressure segments are removed, the residual stress is removed from the support. released in the vertical direction. At this time, the molding sand in the vicinity of the mold is restrained by friction with the frame wall, and the unrestrained central part of the mold is greatly deformed, resulting in a so-called springback, in which the mold surface becomes convex. In addition, 6th to 8th
In the figure, 5 is a table, 7 and 7' are surface plates, 13 and 13' are air supply and exhaust lines, and 10 is an auxiliary frame.

[Problem that the invention seeks to solve]

The present invention has a uniform filling degree by eliminating the reduction in the filling degree due to the large frictional force generated between the mold and the molding sand, and the springback deformation due to the stress remaining in the molding sand during processing, An object of the present invention is to provide a molding method and apparatus that can obtain a precise mold without deformation.

Means for Solving Problem C] In the present invention, inside an auxiliary frame having a low-friction wall surface for holding molding sand, pressure is applied by the lower segment on the model surface side to fill the molding sand. Thereafter, the pressure on the lower segment is increased relative to the pressure on the upper segment, or the pressure on the upper segment is decreased, and the filled molding sand (hereinafter referred to as "sand mold") is transferred from the auxiliary frame to the mold. do. At this time, by making the wall-to-wall dimension of the auxiliary frame slightly smaller than the wall-to-wall dimension of the mold, the stress remaining inside the sand mold is released toward the periphery, and the sand mold is deformed in the layer direction. After that, when the transfer progresses until the top surface of the surface plate is at the same height as the top surface of the auxiliary frame, the lifting of the F segment is stopped and the peripheral segments of the top segment are pressurized. This pressurization progresses filling of the periphery of the sand mold and also fixes the sand mold and the mold frame. Thereafter, the upper and lower segments are raised and lowered, respectively, to complete molding of the mold.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1-5. 1 to 5 show the order of the molding work in this embodiment.

The structure of this embodiment will be explained with reference to FIG. 1. Reference numeral 621 indicates molding sand, and the space formed by the model 22 mounted on the surface plate 27, the auxiliary frame 20, and the formwork 23 mounted thereon. Foundry sand 21 is thrown into the molding area. The surface plate 27 is the table 25
is fixed on top of the auxiliary frame 2 by means of the lower segment 24'.
The molding sand 21 is configured to be able to slide inside the molding sand 21 and pressurize the molding sand 21. The upper segment 24, which is divided into a plurality of parts so as to be able to pressurize or receive pressure on the molding sand 21 at an arbitrary height according to the shape of the model 22, is a mold peripheral segment 4a as shown in FIG. and a mold central segment 4b (control device and actuator not shown) are installed above the mold frame 23. Here, a low friction member 11 is attached to the inner wall of the auxiliary frame 20.

In such a configuration, the dimensional relationship of the auxiliary frame 20, etc. is set as follows: (1) The depth of the auxiliary frame 20 is set to a depth that can accommodate the entire amount of molding sand 21 before pressurized filling at the most. It is desirable to set the depth so that the upper surface of the model 22 does not protrude from the auxiliary frame 20 when the pressurization is completed, even if it is small.

■ The wall-to-wall dimension of the auxiliary frame 20 is set to be slightly smaller than the wall-to-wall dimension of the formwork 23.

In the above configuration, the order and effects of the molding work will be explained.

FIG. 1 shows a state in which foundry sand 21 is surrounded by an auxiliary frame 20 and a mold 23 and placed on a surface plate 27 and a model 22. (The device for charging the molding sand 21 is not shown.) FIG. 2 shows a state in which the upper segment 24 has descended inside the mold 23 and is in contact with the molding sand 21. At this time, the receiving pressure of the upper segment 24 is set to zero (thereby, even if the upper surface of the cast molding sand 21 is uneven, the height of the upper segment 24 follows the shape of the molding sand 21).

Next, as shown in FIG. 3, when the upper segment 24 is brought into a pressure receiving state and the lower segment 24' is brought into a pressurized state, the molding sand 21 is filled.

At this time, since the molding sand 21 is filled by the surface plate 27 and the model 22 via the table 25 placed on the lower segment 24', the side of the model 22 where filling is most needed during casting is made up of. Further, the lateral component force generated during filling is efficiently received by the upper segment 24 by the low friction member 11 attached to the inner wall of the auxiliary frame 20 without generating a large frictional force.

Next, in FIG. 4, when the pressure applied to the upper segment 24 is decreased or the pressure applied to the lower segment 24' is increased, the difference between the applied pressure and the received pressure causes the upper segment 24, the molding sand 21, the model 22, and the The board 27, table 25 and lower segment 24' are raised. During the rising process, the filled molding sand 21 moves from the auxiliary frame 20 into the form frame 23.

During the movement, the molding sand 21 moves from the auxiliary frame 20, which has a smaller wall-to-wall dimension, to the mold frame 23, which has a slightly larger wall-to-wall dimension, thereby creating a gap around the molding sand 21. Due to this gap, the internal stress remaining in the foundry sand 21 is released.

The lifting progresses until the upper surface of the surface plate 27 coincides with the upper surface of the auxiliary frame 20. When the upper surface of the fixed fi 27 and the upper surface of the auxiliary frame 20 coincide, the lower segment 24' is stopped from rising and the peripheral segment 4a of the upper segment 24 is changed from receiving pressure to applying pressure. The molding sand 21 filled with the internal stress removed is pressurized only at the periphery by the peripheral segment 4a, and as a result, the molding sand 21 is fixed to the mold 23.

In FIG. 5, when the pressure on the peripheral segment 4a is stopped and the upper and lower segments 24 and 24' are raised and lowered, the molding sand 21 filled in the mold 23 is left behind and the molding is completed. do.

〔Effect of the invention〕

According to the present invention, when filling with foundry sand, it is not filled in the mold with high wall friction, but is carried out in an auxiliary frame fitted with a low-friction material, so it is efficiently filled, and the surrounding areas, which were difficult to fill in the past, are also filled. Furthermore, in the process of transferring the molding sand from the auxiliary frame to the mold, the internal stress that causes deformation can be released, making it possible to obtain a precise mold without deformation.

[Brief explanation of the drawing]

FIG. 1 shows a state in which foundry sand 21 is introduced. FIG. 2 shows the state in which the upper segment 24 has been lowered and is in contact with the foundry sand 21. FIG. 3 shows a state in which the upper segment 24 receives pressure, the lower segment 24' is pressurized, and the molding sand 21 is filled. FIG. 4 shows a state in which the upper end of the surface plate 27 rises to the upper end of the auxiliary frame 20 as the lower pressure segment 24' rises, and then the mold peripheral segment 4a is pressurized. Figure 5 shows the upper and lower segments) 24 and 24' retracted and separated from the mold. 6 to 8 show cross-sectional views of a conventional molding apparatus. 21 is foundry sand, 22 is a model, 23 is a mold, and 24 is an upper pressurizing segment, which is composed of a mold peripheral segment 4a and a mold central segment 4b. 24' is a lower pressure segment, 25 is a table, 27 is a surface plate, 2
0 indicates an auxiliary frame, and 11 indicates a low friction member attached to the inner wall of the auxiliary frame 20. Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1) A molding method in which a surface plate and a model are placed on a lower pressurizing segment, and a plurality of upper segments are capable of independently and arbitrarily receiving and pressurizing foundry sand depending on the shape of the model. In this method, a low-friction member is attached to the inner wall surface, and after filling molding sand in an auxiliary frame having a wall-to-wall dimension slightly smaller than the wall-to-wall dimension of the formwork, the molding sand is transferred into the formwork, and the molding sand is transferred to the formwork by the upper peripheral segment. A molding method characterized by fixing. 2) In a molding device that has a surface plate and a model placed on the lower pressurizing segment and has multiple upper segments that can receive and pressurize foundry sand independently depending on the shape of the model, there is a It is characterized by an auxiliary frame to which a friction member is attached, a wall-to-wall dimension slightly smaller than that between the walls of the formwork, and a height for storing molding sand before filling, and the formwork is placed on the auxiliary frame. Mold making equipment.