JPH0438500B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a mold making device.

Recent mold making equipment, especially for mass-produced castings, improves manufacturing dimensional accuracy, improves productivity (increases molding speed), and improves the working environment (noise countermeasures).
These requirements are becoming stricter.

The pressurizing mechanism of a conventional mold making machine is shown in FIG. In addition, each symbol in the figure is as follows.

01... Upper pressure cylinder, 02... Upper pressure head, 03... Upper pressure segment, 04...
...Model, 05...Lower frame, 06...Cast flask,
07...Model mounting stand, 08...Jolt mechanism section,
09... Upper frame, 10... Foundry sand, 11...
...Oil supply and drainage hole, 12...Oil supply and drainage hole.

In the molding machine shown in FIG. 1, a mold 06 is placed on a model mount 07 on which a model 04 is placed, and after casting sand 10 is poured into it, the upper pressure head 02 is lowered by an upper pressure cylinder 01. Then, the molding sand 10 is pressurized by the upper pressurizing segment 03, and the model mount 07, the model 04, the flask 06, and the molding sand 10 are vibrated by the attached joint mechanism 08, and the molding sand 10 is filled. Furthermore, the upper pressurizing segment 03 is lowered by a cylinder attached to the upper pressurizing head 02 to perform filling according to the shape of the model.

As described above, the molding machine shown in FIG. 1 has a structure in which pressure is applied only from the upper part of the mold (the side opposite to the model surface), and the upper pressurizing segment has a small number of divisions, and each segment is large. Therefore, there were the following drawbacks.

(1) In order to densely fill the model surface and parting surface B (surface plate surface), increase the pressure in anticipation of pressure transmission loss (due to friction between sand grains, friction with the frame wall, etc.) . This results in an increase in the size of the hydraulic system and loss of energy.

(2) Filling of the frame wall surface, parting surface, and island portion (pocket) will be inadequate (see frame wall surface A, parting surface B, and island portion C in Figure 1).

(3) The upper part of the mold, which does not require much filling, is overfilled. This results in casting defects due to poor air permeability and poor sand collapsibility during mold disassembly.

To prevent these drawbacks, a bolt mechanism is usually attached to apply vibrations during molding. However, this also causes the following drawbacks.

(1) The addition of a bolt mechanism necessitates an increase in the size of the equipment foundation as a vibration-proofing measure.

(2) The bolt accelerates wear of the frame positioning pins and bushes. This results in a decrease in product dimensional accuracy.

(3) The noise generated during twisting causes deterioration of the working environment.

In order to improve the above drawbacks, the present inventors applied pressure also from the bottom surface of the mold (model surface and parting surface).
The double-sided pressure molding method and device as shown in Figure 2 were previously applied for (Japanese Patent Application No. 53-97012, 53-97013).
No. 53-130860. As a result, the filling of the frame wall surface and parting surface (including the model surface) was improved, and vibration noise was significantly reduced. Each symbol in FIG. 2 is as follows.

01... Upper pressure cylinder, 02... Upper pressure head, 03... Upper pressure segment, 04...
...Model, 05...Lower frame, 06...Cast flask,
07...Model mounting stand, 09...Upper frame, 1
0... Foundry sand, 11... Oil supply/drain hole, 12... Oil supply/drain hole, 13... Upper additional frame, 14... Lower additional frame, 15... Casting flask and additional frame fixing device, 16...
Lower pressure head, 17...lower pressure cylinder.

In the double-sided pressure molding apparatus shown in Fig. 2, model 04
The model mounting base 07 on which the
Set it at 6. The model mount 07 and the lower pressure head 16 are pushed into the lower extension frame 14 by a lower pressure cylinder 17. Next, the lower additional frame 14, the casting flask 06, and the upper additional frame 13 are installed in this order on the lower frame 05, and molding sand 10 is poured inside.

The mold is formed by compressing the foundry sand 10 (mechanically compacting it to reduce its volume) to generate strength. Therefore, when pressurizing from above, the upper additional frame 13 requires an extra amount of molding sand corresponding to the compression of the molding sand 10, and is a space for this purpose. Further, the lower additional frame 14 is a space into which excess molding sand 10 necessary for compression is similarly introduced from the lower part.

To fill the molding sand 10 under pressure, first, the upper pressurizing cylinder 01 is lowered and the upper pressurizing segment 0
3. Slightly pressurize the molding sand 10. At the same time, or a little later, the lower pressurizing cylinder 17 pushes up the lower pressurizing head 16, the model mount 07, and the model 04, and pressurizes the molding sand 10. Subsequently, the upper pressurizing segment 03 is lowered using a cylinder disposed in the upper pressurizing head 02, and the molding sand 10 is pressurized to complete the molding. in this case,
The upper and lower additional flasks 13 and 14 and the flask 06 are attached to the fixing device 1.
It is fixed by 5.

However, even with the above-mentioned double-sided pressurization molding device, filling of the island portion (pocket) may not always be carried out sufficiently.

Further, as shown in FIG. 1, the upper pressurizing segment is often of a multi-head type so that the pressurizing depth changes depending on the shape of the model, but this also has the following drawbacks.

(1) The segment hydraulic system is usually only divided into two or three blocks, and the movement (pressure force, time, amount of descent) of each segment is not completely free.

(2) As shown in Figure 3, in the conventional pressurization from above, the pressurization pattern is simultaneous pressurization → partial pressurization, so the shearing force in the sand-filled area caused by simultaneous pressurization The effective pressurizing force of partial pressurization becomes smaller by the amount (〓H).For this reason, the pressurization according to the model shape becomes insufficient.

(3) Furthermore, as shown in Fig. 4, since the conventional upper pressurizing segment 03 has a large shape, when molding with a model 04 with large irregularities, the pressurizing force is supported by the high part P of the model (katsugi phenomenon ), if the island Q is low, the pressing force will not be transmitted and the filling will be insufficient.

The present invention eliminates the drawbacks of the conventional mold making mechanism described above and provides a mold making apparatus that can uniformly fill molding sand.

That is, the present invention provides for the upper pressurizing head, the plurality of columnar pressurizing segments provided in the upper pressurizing head, the lower pressurizing head, and their pressurizing force, pressurizing order, and raising/lowering amounts in advance. In a mold making apparatus equipped with an automatic control means that operates according to a predetermined program, the rear end of the rod inserted into each of the columnar pressure segments is fixed in the upper pressure head, and the columnar pressure segments is attached to the rod so that it can be raised and lowered, and at least a part of the outer wall of the columnar pressure segment slides with the outer wall of another adjacent columnar pressure segment to support each other. This is a mold making device.

In addition, as a specific mode of sliding of the adjacent columnar pressurizing segments, the cross-sectional shape of the columnar pressurizing segment is polygonal, and the columnar pressurizing segments are made to slide on the entire outer wall of another adjacent columnar pressurizing segment, or the above-mentioned method is used. A structure can be adopted in which the columnar pressure segment is slid against the outer wall by the fins or keys of other adjacent columnar pressure segments.

FIG. 5 is a diagram showing the structure of the mold making apparatus of the present invention. Each symbol in the figure is as follows.

01... Upper pressure cylinder, 02... Upper pressure head, 03... Column pressure segment, 04...
...Model, 05...Lower frame, 06...Cast flask,
07...Model mounting stand, 09...Upper frame, 1
0... Foundry sand, 11... Oil supply and drainage hole, 13... Upper additional frame, 14... Lower additional frame, 15... Casting flask and additional frame fixing device, 16... Lower pressure head, 17
...Lower pressure cylinder.

FIG. 6 is a diagram showing an example of the structure of a columnar pressure segment portion. Figure 6 A shows the hydraulic cylinder.
FIG. 6B shows an example of raising and lowering by a motor.
Each symbol in the figure is as follows.

02... Column pressure head, 03... Upper pressure segment, 18... Rod, 19... Piston,
20...Cylinder, 21...Oil supply and drain hole, 22...
...Rod (with screw), 23...Thrust bearing, 2
4...screw, 25...motor.

FIG. 7 is a diagram showing an example of the cross-sectional shape of a columnar pressurizing segment. FIG. 7A shows an example in which the segments slide together, and FIG. 7B shows an example in which they slide by means of fins or keys. Each symbol in the figure is as follows.

03... Column pressure segment, 18 or 22...
...rod (with piston or screw), 26...fin or key.

FIG. 10 shows a system diagram of the hydraulic system and control system. Each symbol in the figure is as follows.

02... Column pressure head, 03... Upper pressure segment, 04... Model, 05... Lower frame, 06... Casting flask, 07... Model mount, 16...
...Lower pressure head, 17...Lower pressure cylinder, 18...Rod, 19...Piston, 20...
...Cylinder, 30...Hydraulic pump, 31,3
1'...Directional switching valve, 32, 32'...Hydraulic pressure adjustment valve, 33...Pressure adjustment valve, 34...Check valve, 35
... Throttle valve (with check valve), 36 ... Pressure switch,
37... Relief valve, 38... Oil tank, 39...
...Pressure detector, 40...Solenoid valve, 41...Control program.

The operation of the molding apparatus according to the present invention is illustrated in FIGS.
This will be explained according to Figure 0.

(1) Attach the model mount 07 on which the model 04 is placed to the upper surface of the lower pressure head 16, and operate the lower pressure cylinder 17 so that the upper surface of the model mount 07 is approximately the same as the upper surface of the lower frame 05. Adjust so that

(2) Next, the lower additional frame 14, the casting flask 06, and the upper additional frame 13 are placed on the upper surface of the lower frame 05 in this order. In this case, the model mount 07 should be smoothly inserted into the lower extension frame 14. Furthermore, the lower additional frame 14 is unnecessary if the model mount 07 is designed to be able to fit into any position within the lower frame 05 as shown in FIG. Not a mandatory requirement.

(3) Next, from the sand charging device (not shown),
6 (upper/lower additional frames 13, 14), model mounting stand 0
Casting sand is poured into the space formed in step 7.

(4) After the sand feeding device has retreated, operate the upper pressurizing cylinder 01 to lower the upper pressurizing head 02 until the tip of the columnar pressurizing segment 03 touches the upper surface of the molding sand 10, and at the same time fix it. Device 1
At step 5, the casting flask 06 and upper and lower additional flasks 13 and 14 are fixed. The operation of the model fixing device 15 is as follows.
It may be performed before the operation of the columnar pressurizing segment 03.

(5) Next, the molding sand 10 is pressurized and molded, but this is done according to a predetermined program. First, the columnar pressurizing segment 03 is lowered by the cylinder built into the upper pressurizing head 02, and the solenoid valve 40 in the hydraulic system opens with a slight time difference starting from the thickest part of the sand, and the molding sand 10 is released. Apply pressure. At this time, the directional control valve 31 in the hydraulic system of the segment cylinder 20
energizes the "extension" coil, and the oil pressure regulating valve 32 is adjusted to a predetermined pressure.

(6) When the columnar pressurizing segment 03 descends and the oil pressure in the cylinder 20 rises, the pressure in the hydraulic system of a specific upper segment is detected by the pressure detector 39. The position of the columnar pressurizing segment that detects the oil pressure varies depending on the shape of the model, the molding steps, etc., and cannot be specified. That is, it differs depending on the nature of the mold to be manufactured, such as in the case of a columnar pressure segment disposed around the mold, or in the case of a columnar pressure segment that started operating last. Thus, when a predetermined pressure is reached, the lower pressurizing cylinder 17 is activated and the lower pressurizing head 1 is activated.
6 rises, and as shown in Figure 9, model 04
until the top surface of the model mount 07 on which the mold is placed is approximately the same as the top surface of the lower additional frame 14 (it is not possible to enter the casting flask 06). Pressure is applied to the molding sand 10 from the bottom until it becomes substantially the same as ( ). At this time, the columnar pressurizing segment 03 continues to pressurize to the adjusted pressure. In addition, model mounting stand 0
The reason why the upper surface of the mold 7 was not allowed to enter the flask 06 is that when casting is performed using a formed mold, molten steel leaks from the part b, as shown in FIG. 11A. In addition, if the upper surface of the model mount 07 does not reach the lower surface of the casting flask 06 (that is, the upper surface of the lower additional frame 14), as shown in FIG. When molten steel is injected, it may leak from part a.

(7) Pressure within the columnar pressure segment cylinder 20 and pressure within the lower pressure cylinder 17 (or
When the position of the model mount 07) reaches a predetermined pressure, the pressure regulating valve 33 closes its path, and as a result, the flow of oil is stopped and the pressure on the discharge side of the hydraulic pump 30 is adjusted to the setting of the relief valve 37. This is detected by the pressure switch 36, and assuming that the pressurization operation has been completed, the "retraction" side of the directional control valves 31, 31' is energized, all cylinders are retracted, and the model 04 is The mold is removed and the molding is completed.

In the device according to the invention, in principle each cylinder 20 is provided with a separate hydraulic path. However, the cylinder that pressurizes the peripheral part of the flask can also be used as a shared path. In addition, as shown in FIG. 6B, when using the motor 25, all the columnar pressure segments 03 are operated by ON-OFF switches, and the columnar pressure segments 03 are operated instead of oil pressure detection.
3 is detected and controlled by a program. Therefore, the hydraulic system for the columnar pressurizing segment in FIG. 10 is completely abolished, and only the switch and the electric system for position detection are used. In addition to the above methods, there are various known methods for detecting the position, and these can also be used.

In this way, the upper pressurizing segment 0 of the conventional device
3 has a mechanism in which a cylinder is fixed to the upper pressure head 02, a segment is attached to the tip of the rod, and the molding sand is pressurized by raising and lowering the rod, but due to the installation of the cylinder, piping, etc. However, in the present invention, the rod 18 is fixed, the cylinder 20 is made to slide between adjacent cylinders, and the tip of the cylinder 20 can be used as a segment to pressurize the molding sand. (See Figure 6).

Further, the cross-sectional shape of the columnar pressurizing segments 03 is polygonal, and they are made to slide against each other. Furthermore, it is also possible to make the sliding movement using fins or keys 26 (see FIG. 7).

The effects of the casting mold apparatus of the present invention will be explained below.

(1) Since pressure is applied directly to the area that requires filling from both the top and bottom, there is less pressure loss due to friction, and the required pressure can be reduced. Further, a bolt mechanism is not required, and the drawbacks associated therewith are also eliminated.
This makes it possible to downsize the device and reduce noise.

(2) Since the columnar pressure segments slide with each other and support each other, the cross-sectional area can be reduced, which allows the island portions (pockets) of the model to be sufficiently filled, and the filling to be performed faithfully to the model shape. It will be done.
This makes it possible to uniformly fill the mold, improve the dimensional accuracy of the product, and reduce the weight of the product.

(3) Parts with large thickness of casting sand and islands (pockets)
Since the part is pressurized before other parts, the part concerned can be filled uniformly, and since the part is pressurized in advance with a time difference, there is no loss of pressurizing force due to the shear force of the foundry sand. This makes it possible to uniformly fill the mold, improve the dimensional accuracy of the product, and reduce the weight of the product.

(4) When pressurizing both sides of the mold, the timing of applying pressure from the top and bottom is important, and molds of uniform quality can be automatically created using program control.

[Brief explanation of drawings]

FIG. 1 shows a pressurizing mechanism of a conventional mold making machine, and FIG. 2 shows the structure of a conventional double-sided press molding apparatus. FIGS. 3 and 4 are explanatory diagrams showing pressure patterns of the conventional device. FIG. 5 shows the structure of the mold making apparatus of the present invention, FIG. 6 shows an example of the structure of the columnar pressure segment part of the present invention, and FIG.
The figure shows an example of the cross-sectional shape of the columnar pressure segment of the present invention. FIG. 8 is a diagram showing another embodiment of the device of the present invention. FIG. 9 is a diagram showing a state in which the lower pressurizing cylinder according to the present invention is in operation. FIG. 10 shows a system diagram of the hydraulic system and control system used in the present invention. FIG. 11 is a diagram for explaining the disadvantages of casting using a mold formed in an undesirable manner.

Claims (1)

[Claims] 1 Regarding the upper pressurizing head, the plurality of columnar pressurizing segments provided in the upper pressurizing head, the lower pressurizing head, and their pressurizing force, pressurizing order, and amount of elevation and descent. In a mold making apparatus equipped with an automatic control means operated according to a predetermined program, the rear end of the rod inserted into each of the columnar pressure segments is fixed in the upper pressure head, and the columnar pressure The segment is attached to the rod so as to be freely raised and lowered, and at least a part of the outer wall of the columnar pressure segment slides with the outer wall of another adjacent columnar pressure segment to support each other. Mold making equipment. 2. The mold making apparatus according to claim 1, wherein the columnar pressure segment has a polygonal cross-sectional shape and is configured to slide on the entire outer wall of another adjacent columnar pressure segment. 3. The mold making apparatus according to claim 1, characterized in that a structure is adopted in which the columnar pressure segment slides on the outer wall of the columnar pressure segment by means of fins or keys of other adjacent columnar pressure segments.