JPS6384756A - Anti-gravity mold - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to anti-gravity casting of molten metal;
- Layer In particular, it relates to a self-supporting gas-permeable resin-bonded sand thin-walled mold used therefor.

The anti-gravity casting method involves sealing a gas-permeable mold inside the mouth of a vacuum chamber, immersing the lower side of the mold in the melt, and pulling the air from the vacuum chamber to place the mold at the bottom of the mold. One such method, which refers to siphoning the melt into a mold through one or more weirs, is described in U.S. Pat.
No. 108, in which the melt is formed in a resin-bonded sand shell mold, which consists of upper and lower parts hermetically bonded to each other along a horizontal parting line outside the vacuum chamber. Such molds, which contain the mold section (ie, the vacuum chamber engages the upper mold), are susceptible to air intrusion at the parting line.

Furthermore, the outer surface of the upper mold, as formed, is rough and cannot be practically sealed against the mouth of the vacuum chamber. Therefore, the upper mold must be further processed after molding to ensure that its upper surface is flattened for sealing engagement with the vacuum chamber.

It is an object of the present invention to form the flat sealing surface of the mold adjacent to the vacuum chamber simultaneously with the remaining mold parts (i.e., there are no additional processing steps), and to further improve the mold parting line where the parting line of the mold is within the vacuum chamber. An object of the present invention is to provide a resin bonded sand shell mold for anti-gravity casting.

Another object of the invention is to provide an improved mold as described above which has a ubiquitous seal at the parting line to prevent melt from escaping into the vacuum chamber.

These and other objects and advantages of the present invention will become more readily apparent from the following description taken in conjunction with the drawings.

Moon W type base J - The present invention has a gas-permeable upper mold that is sealed against the lower mold, and the lower mold has a sealing surface that is not only aligned with the upper mold but also directly connected with the vacuum chamber. A self-supporting resin-bonded sand anti-gravity casting shell mold configured to include an upper and lower mold parting line seal within a vacuum chamber is contemplated. The term "shell type" refers to molding that is made to almost match the molding model, and only the resin that is in close contact with the model is cured (for example, by heat 1, a catalyst, a chemical reaction, etc.) It is used in the general sense of a thin-walled resin-bonded sand mold that forms Applies to all types of resin-bonded sand molds, regardless of mechanism, and therefore made by either hot (i.e., thermosetting resin) box method or cold (i.e., catalytic resin) box method. According to the present invention, which also includes a mold, the lower mold is molded larger than the upper mold and includes a flange extending outwardly from the periphery of the upper mold at a parting line between the upper and lower mold parts. The top surface of the bottom mold flange is molded to match the molding surface of the bottom molding model and the remaining bottom mold part is molded at the same time, thus consistently and reliably without the need for separate operations. It can have almost any shape or contour. During casting, the flange is secured directly to the vacuum chamber of the casting equipment, forming a seal between the top surface of the flange and the mouth of the vacuum chamber. As a result, the seal at the parting line between the upper and lower mold parts is surrounded by a vacuum chamber, and no air can enter the mold through this parting line. The sealing surfaces of the upper and lower mold parts are glued together to form a single mold. Preferably, the mold has at least two adhesive-filled grip-in groove joints that form a labyrinth seal surrounding the mold cavity and prevent escape of melt from the mold cavity into the vacuum chamber.

In order to explain the traditional shell mold casting method, Figures 1a to 1d and 2a to 2d show how to manufacture shell mold parts with sand mixture and thermosetting resin. The well-known dump box method is illustrative. Figures 1a to 1d relate to molding of the lower mold part, and Figures 2a to 2d relate to molding of the lower mold part.
The figure relates to the upper mold part. Lower mold molding model 2
The upper molding model 14 is installed in the box 4 (see Figures 1a and 2a). Next, it is heated to a predetermined temperature by an appropriate means (not shown), and any Partially cure the resin. After heating model 2.14 in this manner, sand resin mixture 8,18 was added to model 2.
, 14 and left in place for a sufficient period of time for the resin in the sand layer 12, 20 adjacent to the models 2, 14 to partially cure the resin and bind the sand;
Ensure that the sand layer 12,20 remains attached to the model 2,14 when it is turned upside down during the next working step.Typically, the thickness of the sand layer 12,20 ranges from about 1/4 inch to about 1/4 inch. 37
4 inches (about 6.35 mm to about 19.05 mm) or thicker depending on the temperature of the model, the time it remains on the model, and the composition of the resin in the sand mixture. Following partial curing of the resin in the sand layer 12.20, box 1
4 upside down and loose sand or uncured resin 8', 18'
are dropped from the models 2 and 14 (Figures 1a and 2a).

Finally, return the box 4 to the upright position Figure 1d, Figure 2.
d), the sand layer 12.20 is sufficiently hardened to form a hard shell 12', 20'. These shells approximately correspond to the shapes of the respective models 2 and 14. In connection with this, inner surfaces 38c and 38d (upper mold and lower mold, respectively)
almost corresponds to the molding surfaces 10, 6 of the corresponding model, and the outer surface 4
0c and 40d (upper and lower molds, respectively) are very rough;
As best shown in FIG. 4, the shape is almost similar to that of the model.

A fully assembled mold 22 (see FIG. 3) is obtained by gluing the upper mold 20' and the lower mold 12' together at the cutoff point s24. It is applied to the sealing surface 21 of the mold 12' and clamped to the sealing surface 16 of the upper mold 20' until the adhesive hardens.

For this purpose, Georgia Pacific Co.
Thermosetting adhesives, such as 5SGIO, have proven effective. The adhesive is applied while the sealing surface 21 of the lower mold is still hot, and the upper and lower mold parts are directly connected so that the adhesive is cured by the heat from there. A weir 2 is provided at the bottom of the lower mold 12' to allow the melt to enter from the mold cavity 26.
8 is a provision. This weir 28 can be easily formed during lower mold molding by setting a plurality of pins 30 on the lower mold molding model 2 and surrounding them with sand. The top 32 of the sand mound 34 formed around the pin 30 is cut away to open the end of the weir 28 to allow access to the melt.

Alternatively, weir 28 may be formed with a drill.

FIG. 5 illustrates the anti-gravity casting method of U.S. Pat. The vacuum chamber 44 is filled with melt by drawing air through the appropriate outlet 48. As formed, the rough outer surface of upper mold 20' made it virtually impossible to obtain an adequate seal between vacuum chamber 44 and upper surface 40c. Therefore, it was necessary to flatten the upper surface of the upper mold 20' to form a sufficiently smooth surface 50 and seal it against the mouth 42 of the vacuum chamber 44. To form this flat sealing surface 50, while still in the plastic state, the outer edge of the upper mold 20'' is compressed to form a ridge 58, forming a flat upper surface 50 as well as an undercut 54. The undercut 54 is used to attach the mold 22 to the vacuum chamber 44 by means of clips 60 or the like.

A ribbon 56 of compressible insulating material is placed between the top surface 50 and the vacuum chamber 44 to prevent leakage therethrough in the event of irregularities in the surface 50 and/or lip 58 of the vacuum chamber 44.
It may also be provided between the flange-like lips 58 of the. One such ribbon material is commercially available from Carborundum Co. under the tradename Fiberfrax. Fiberfrax ribbon 56 is approximately 1/8 inch (3,175 mm) thick when received from the manufacturer and compressed to approximately 1/16 inch (1,175 mm) when tightened between mold 22 and lip 58. 588 mm) becomes 0
As shown, the clip 60 engages the lower surface of the compressed ridge 52 at the undercut 54 and also engages the flange lip 58 to compress the ribbon 56 and move the upper mold 20 to the mouth of the vacuum chamber 44. effectively sealing against section 42.

6a and 6b show a lower mold 64 and an upper mold 62 according to the present invention. The upper mold 62 is smaller than the lower mold 64, and when these upper and lower mold parts are glued together, the lower mold 64 and the upper mold 62 are shown. An outer portion 66 of 64 projects beyond the periphery 68 of the upper mold 62 to provide a flange 70 extending outwardly of the periphery 68 of the upper mold 62 . The surface 72 of the flange 70 is the lower die 6
At the same time when forming the other parts of 4, they are molded to match the upper surface 74 of the lower model 75. One side 72 can therefore be precisely shaped into any configuration desired to seal against the mouth of the vacuum chamber. The lower molds thus produced will all have the same shape and dimensions without the need for any additional processing or molding machining operations. In the particular embodiment shown, surface 72 is made flat and smooth to provide a butt seal against the mouth of vacuum chamber 44. It is thus possible to seal the vacuum chamber 44 directly to the lower mold 64, with the adhesive bond between the sealing surfaces 76, 78 of the upper mold 62 and the lower mold 64 being located within the vacuum chamber, and the air in the vacuum chamber 44 When , it is impossible for air to enter the mold cavity through the parting line between the upper and lower mold parts.

Mold cavity 26 is preferably surrounded by a labyrinth seal to prevent escape of melt from the mold cavity into vacuum chamber 44 .

In this case, the sealing surface 76 of the upper mold 62 has two surfaces surrounding the mold cavity.
One or more continuous flat-topped beads 80 will be included.

At the same time, the sealing surface 78 of the lower mold 64 includes a continuous groove 82 that generally corresponds to the bead 80, into which the bead will enter. The bead 80 is slightly smaller than the groove 82 (for example, about 0.005 inch = about 0.127 mm smaller).
, when putting the adhesive into the groove, it will flow between the bead surface and the groove surface 0 During assembly, the thermoplastic adhesive (
For example, 5SGIO) is applied to the surface of the thick lower die 64 to fill the groove 82.

There is often a break in the adhesive bonded to the surface 78 that adheres to the sealing surface 78, through which melt may sometimes escape. When the groove 82 is filled with adhesive,
Such leakage will no longer occur. In this regard, during assembly, the flat-topped bead 80 evenly redistributes adhesive to the bottom of the groove, providing a generally continuous band of sealant surrounding the mold cavity. In the unlikely event that a belt breaks, it is highly unlikely that an interruption in one belt will coincide with an interruption in another belt, creating a tortuous escape route and a very effective seal. can get.

In addition to the sealing surface 78, the flange 70 of the lower mold serves as a means for attaching the lower mold 64 directly to the vacuum chamber 44. A bracket 84 welded to the top of the vacuum chamber 44 serves as a tension spring 86.
The bolt 88 connects the flange 70 to the spring 8.
6, the sealing ribbon 56 is compressed, and the vacuum chamber 4 is
The mold is sealed inside the mouth of 4.

Although the invention has been described with reference to particular embodiments thereof, it is to be understood that the invention is not intended to be so limited, but rather is limited only to the extent set forth in the claims.

[Brief explanation of the drawing]

Figures 1a to 1d and 2a to 2d are
1 is a diagram illustrating a conventional dump box method for making a shell-shaped part from a thermoset resin bond. FIG. FIG. 3 is a side sectional view of a conventional anti-gravity casting shell mold assembled with mold sections formed by the methods of FIGS. 1a-1d and 2a-2d. FIG. 4 is a view in the 4-4 direction of FIG. 3. FIG. 5 is a side sectional view of a conventional shell mold (FIG. 3) sealed to and connected to a vacuum chamber and immersed in the melt. Figures 6a and 6b are views similar to Figures 1d and 2d, showing shell-shaped parts formed in accordance with the present invention. Figure 7 shows how the mold part shown in Figure 6 is assembled and connected to the vacuum chamber.
1 is a sectional side view of a mold according to the invention immersed in a melt; FIG. [Explanation of symbols of main parts Lower mold molding model ・・・・・・・・・・・・・・・・・・
・・・・・・2 boxes ・・・－・・・・・・・・・・・・
・・・・・・・・・・・・・・・4 sand layers ・・・・
・・・・・・・・・・・・・・・・・・ 12. 2
0 upper mold molding model ・・・・・・・・・・・・・・・・・・
・・・・・・14 Sand/resin mixture ・・・・・・・・・
・・・・・・8,18 shells・・・・・・・・・・
......12', 20' sealing surface...
・・・・・・・・・・・・・・・・・・・・・・・・21
Mold・・・・・・・・・・・・・・・・・・・・・
・・・・・・22 Parting line・・・・・・・・・・・・・・・
・・・・・・・・・・・・24 Weir・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・28
Pin ・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・ 30 Vacuum chamber・・・・・・・・・
・・・・・・・・・・・・・・・・・・44 Lips...
・・・・・・・・・・・・・・・・・・・・・・・・
58 Clips ・・・・・・・・・・・・・・・・・・
・・・・・・・・・60 lower type ・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・ 64 top
Type ・・・・・・・・・・・・・・・・・・
・・・・・・ 62 flange ・・・・・・・・・・・・
・・・・・・・・・・・・・・・70 lower model ・・
・・・・・・・・・・・・・・・・・・・・・・・・
75 Sealing surface・・・・・・・・・・・・・・・・・・
・・・76, 78 bead ・・・・・・・・・
・・・・・・・・・・・・・・・・・・ 80 grooves...
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・82 Procedural amendment October 31, 1986

Claims (1)

[Claims] 1. Inside the shell mold, a porous, consumable shell mold with a bottom sprue is immersed in molten metal, and air is drawn to draw the metal into the shell mold using a vacuum pulling anti-gravity casting method. an apparatus for forming a metal article into a metal article, wherein the upper mold portion of the shell mold includes a gas permeable resin-bonded sand shell formed by casting into an upper molding die; The lower mold part of the shell mold has a peripheral edge that constitutes a mold cavity for molding and forms a first sealing surface on the lower side of the upper mold part between the mold cavity and the mold cavity, and the lower mold part of the shell mold is connected to the lower mold. including a resin-bonded sand shell formed by casting into a molding pattern, the lower mold portion further defining a mold cavity and having a second upwardly directed sealing surface surrounding the mold cavity; , there is an adhesive bonding and sealing the first and second sealing surfaces together at a parting line between the first and second sealing surfaces, and the lower mold part has a flange, the flange extending beyond the periphery. the flange extending outwardly of the second sealing surface and having a generally flat upper surface formed to match the lower molding pattern when the lower mold section is cast; a vacuum chamber is formed above and surrounded by the upper mold, the vacuum chamber having a lip on its underside that sealingly engages the upper surface of the flange, and the shell mold is immersed in molten metal. The apparatus is sometimes provided with means for sucking air from the vacuum chamber into the shell mold sufficiently to suck up the molten metal. 2. The apparatus of claim 1, wherein a substantially continuous, integral, flat-topped bead of resin-bonded sand is integrally molded with at least one of the sealing surfaces and surrounds the mold cavity. A substantially continuous groove is molded into the other sealing surface and surrounds the mold cavity, and the bead and groove are aligned like an inner groove knob, and the flat top of the bead and the groove are aligned. A narrow space is formed between the mold and the bottom of the mold, and the adhesive almost fills the space and prevents molten metal from escaping from the mold cavity to the vacuum chamber through the parting line during casting. A device characterized by: 3. The apparatus of claim 2, wherein the sealing surface includes at least two beads and grooves surrounding the mold cavity. 4. A porous, consumable shell mold with a bottom sprue is immersed in molten metal, and a metal article is formed in the shell mold by a vacuum anti-gravity casting method in which air is drawn to suck up the metal into the shell mold. an apparatus, wherein the upper mold portion of the shell mold includes a gas permeable resin-bonded sand shell formed by casting into an upper molding die, the upper mold portion defining a mold cavity for molding the article; and has a periphery forming a first sealing surface on the lower side of the upper mold part between the mold cavity and the lower mold part of the shell mold to be cast into the lower molding model. the lower mold portion further defining a mold cavity and having a second upwardly facing sealing surface surrounding the mold cavity; Means are provided for bringing the two sealing surfaces into sealing engagement with each other at the parting line between the two sealing surfaces, said lower mold portion having a flange extending beyond said periphery to said second sealing surface. the flange has a generally flat upper surface formed to match the lower molding pattern when the lower mold part is cast, and the upper a vacuum chamber is formed surrounded by the mold, the vacuum chamber having a lip on its underside in sealing engagement with the upper surface of the flange, the shell mold being immersed in molten metal; Apparatus characterized in that it is provided with means for suctioning sufficient air from said vacuum chamber to draw up molten metal into said vacuum chamber.