KR20080080455A - Method and apparatus for removing a fugitive pattern from a mold - Google Patents

Abstract

A method and an apparatus for removing fugitive patterns from a mold are provided to reduce cracks of the mold during removing the fugitive patterns and to prevent steam from approaching the outer side of the wall of the mold as if the mold is supported by a particle support medium. A method for removing fugitive patterns(10) from the inside of a refractory mold(20) comprises the steps of: injecting condensable steam and a surfactant(SF) into the mold so that the condensable steam and a surfactant are melted by coming into contact with pattern materials; condensing the condensable steam which is placed in the mold and melted by coming into contact with the pattern material; and discharging the pattern material melted in the mold and the condensed steam. A surfactant promotes the exhaust of the steam.

Description

METHOD AND APPARATUS FOR REMOVING A FUGITIVE PATTERN FROM A MOLD}

The present invention relates to a method and apparatus for removing a fugitive pattern from a metal mold.

In general, the well-known "lost wax" investment casting uses fire resistant molds. The fire resistant mold is typically made by building a continuous layer of ceramic particles bonded with an inorganic binder on a consumable (disposable) model material such as wax, plastics and the like. The finished fire resistant mold is generally formed as a shell mold surrounding the consumable model.

The refractory cell mold on the consumable model is typically subjected to model removal, where the model melts out of the cell mold. This operation leaves an empty “green” (unheated) refractory cell mold. Consumable model materials typically have significantly higher coefficients of thermal expansion than materials of refractory cell molds. If the consumable and refractory molds are uniformly heated, the consumable model material will thermally expand more than the refractory mold. This will put pressure on the refractory cell mold and eventually crack the cell mold. To date, the removal of consumable model material has typically been performed by methods such as high pressure steam autoclaving or flash firing to avoid cracking such cell molds. The removal of the consumable model material by high pressure steam autoclaving or flash firing exposes the exterior of the refractory cell mold to high temperatures. This high temperature causes faster heat conduction through the refractory cell mold to melt the surface of the model before the interior of the model thermally expands. The surface layer of this molten model material expands until the model is exposed to the open portion of the mold, pushing out a portion of the liquid surface model material from the mold opening to receive the expanded model material inside the mold. Such a method can cause the fire resistant cell mold to continuously crack unless heat is continuously applied along the surface of the consumable model inside the mold. The connection between the refractory cell mold and the adjacent model together is one of the main reasons for the nonuniform heating of the model. That is, thick areas of the refractory cell mold will prevent heating of the model material, and will locally delay melting of the surface of the model, thereby preventing continuous heating. This fact hinders the movement of the surface liquid model material from the thin mold region further away from the mold opening than the thick mold region. Such interference with the movement of the surface liquid model material causes the build up of model pressure in the distant thinner mold due to thermal expansion of the model material, resulting in cracking of the mold. This problem requires the use of a mold that is strong enough (eg thick enough) to resist the expansion pressure of the model material and often additional vents or vents through the mold to relieve pressure in unconnected expansion models. Requires the use of Stronger or thicker molds and aeration methods are undesirable because they increase the cost of the process.

The plurality of green fire resistant cell molds (without the model) are then loaded into a batch or continuous oven heated by combustion of gas or oil and heated to a temperature of 1600 ° F. to 2000 ° F. Alternatively, the mold may be heated by the method of co-assignee US Pat. No. 6,889,745, which describes heating the mold in the presence or absence of support sand surrounding the mold. The heated refractory mold is removed from the oven and the molten metal or alloy enters the mold and is cast.

The trend in precision casting is to make the refractory cell mold as thin as possible to reduce the cost of the mold as described above. The use of thin cell molds requires the use of a mold support medium to prevent the failure of the mold, as described in US Pat. No. 5,069,271 to Chandley et al. The '271 patent discloses the use of bonded ceramic cell molds made as thin as possible, for example as thin as 0.12 inches thick. The non-bonded support particulate medium fills around the hot fire resistant cell mold after the fire resistant cell mold is removed from the preheated oven. The non-bonded support medium acts to resist the force applied to the cell mold during casting to prevent mold failure.

However, thin cell molds are more likely to crack during model removal operations, such as the above mentioned high pressure steam autoclave or flashfire model removal operations in which the model is melted and removed from the cell mold.

U.S. Patent Application No. 10 / 899,381, filed on July 26, 2004, discloses that the exterior of a mold is placed under a non-condensable gas atmosphere such as ambient air outside the mold, allowing condensable vapors such as steam to enter the interior of the mold. A method of removing a consumable model from a joined refractory mold by contacting and melting the model is disclosed. Condensed vapor and molten model material are discharged out of the mold by reducing the cracking of the mold in the mold.

One aspect of the invention is that in certain embodiments, the mold is contained in contact with the model to melt the model while the exterior of the mold is in a non-condensable gas atmosphere, such as ambient air outside the mold. The present invention provides a method and apparatus for introducing condensable steam such as steam to remove consumable models such as wax or other meltable model materials remaining in the refractory mold. The condensable vapor and the molten model material are discharged out of the mold. The surfactant is newly exposed by lowering the surface tension of the condensable vapor in contact with the consumable model inside the mold and improving the evacuation of the molten model material in the mold so that little model material remains on the inner mold surface. This makes it easier to run out of the mold inner surface.

The pressure difference between the condensable vapor inside the mold and the non-condensable gas atmosphere outside the mold is sufficient to prevent condensable gas from flowing out of the mold outside and non-condensable gas from entering the mold cavity. Small enough The condensable vapor inside the mold and the gaseous atmosphere outside the mold are preferably at substantially the same pressure for this purpose. In this way, when steam is used as the preferred condensable vapor, the steam is condensed inside the mold in contact with the mold while the exterior of the mold remains dry. Condensable vapor containing the surfactant may be introduced into the mold at atmospheric pressure, pressure above atmospheric pressure or pressure below atmospheric pressure, depending on the melting point of the model material.

In an embodiment in accordance with the present invention, steam or other condensable vapor is located inside the mold and / or model spout to release steam or condensable vapor at approximately atmospheric pressure, subatmospheric pressure or higher than atmospheric pressure. Can be supplied to a discharge tube. The surfactant may be delivered to the condensable vapor outside or in the discharge tube after the condensable vapor is released.

Another aspect of the present invention provides a method of removing a consumable model such as wax or other meltable model material remaining in a refractory mold in such a way that the mold is subjected to a combined action of rotation and tilting operations during the model removal process. By providing a method and apparatus, the process of ejecting molten model material from the mold is improved. The mold is inclined at an appropriate angle arbitrarily using a drive motor that tilts the mold and the mold is rotated about an axis using a mold rotation drive motor. The mold tilt angle and the mold rotation speed can be adjusted according to the extent to which the molten wax is expelled from the mold cavity. As the mold is inclined at a fixed angle of inclination with respect to gravity, the mold is rotated. Alternatively, as the mold rotates at each inclination angle or continuously, the mold can be inclined incrementally to the selected inclination angle. In addition, the mold can be continuously tilted while rotating continuously or intermittently. While this aspect of the present invention may be practiced using an arbitrary model removal technique that melts or melts the model, steam or other condensability may be used to heat and melt the consumable model inside the mold while the mold is rotated and inclined. It is also possible to introduce steam.

This embodiment of the present invention can be practiced to remove consumable models, such as wax or other melt model materials, from unsupported casting molds. The present invention can also be used to remove consumable models in casting molds supported by particulate media in a container. For example, the outside of the mold is in contact with the particulate medium and is placed in a non-condensable gas (eg, steam free) atmosphere, introducing steam or other condensable vapor into the mold to contact the model to melt the model, and the outside of the mold And the particulate medium surrounding it condenses the vapor inside the mold where the steam contacts the mold while leaving it in a non-condensable gas atmosphere and discharges the molten master material and the condensed vapor out of the mold.

The pressure difference between the condensable vapor inside the mold and the non-condensable gas atmosphere outside the mold is sufficient to prevent condensable gas from flowing out of the mold outside and non-condensable gas from entering the mold cavity. Small enough The condensable vapor inside the mold and the gas atmosphere outside the mold are preferably at substantially the same pressure for this purpose. In this way, when steam is used as the preferred condensable vapor, the steam is condensed inside the mold in contact with the mold while the exterior of the mold remains dry. The condensable vapor containing the surfactant may be introduced into the mold at atmospheric pressure, pressure below atmospheric pressure or pressure above atmospheric pressure, depending on the melting point of the model material.

In an embodiment in accordance with the present invention, steam or other condensable vapor may be applied to the inside of the mold and / or model spout to release steam or condensable vapor at approximately atmospheric pressure, subatmospheric pressure or higher than atmospheric pressure. It is supplied to a discharge tube which can be located. The surfactant may be introduced into the condensable vapor outside or in the discharge tube after the condensable vapor has been released.

This embodiment of the present invention can be practiced to remove consumable models, such as wax or other melt model materials, from unsupported casting molds. The present invention can also be used to remove consumable models in casting molds supported by particulate media in a container. For example, while the outside of the mold is in contact with the particulate medium and placed under a non-condensable gas (eg, steam-free) atmosphere, steam or other condensable vapor is introduced into the mold to contact the model to melt the model, and the outside of the mold And the particulate medium surrounding it condenses the vapor inside the mold where the steam contacts the mold while leaving it in a non-condensable gas atmosphere and discharges the molten master material and the condensed vapor out of the mold.

The present invention is effective in removing one or more consumable models present in a metal casting fire resistant mold, wherein the metal casting fire resistant mold may have any mold wall thickness and may not be supported by an external particulate medium surrounding the mold or It may be supported. The present invention is additionally effective at removing one or more consumable models while avoiding saturation of the walls of the mold with steam or other condensate, where the steam or condensate may adversely affect the binder used to process the mold. have. The invention can be practiced to reduce cracking of the mold in the process of removing the model and to remove the model material from the mold where steam is difficult to access outside of the mold wall, such as when the mold is supported by particulate support media.

The above and other advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.

The present invention provides an improved method and apparatus for removing one or more consumable models present within the fire resistant mold described in U.S. Patent Application No. 10 / 899,381, filed July 26, 2004, which is incorporated herein by reference. will be. In particular, embodiments of the present invention include a method and apparatus for introducing one or more consumable models present inside a fire resistant mold by introducing a condensable vapor containing a surfactant inside the mold. Condensation vapor and molten model material are discharged out of the mold. The surfactant lowers the surface tension of the condensation vapor in contact with the consumable model within the mold, and the molten model material flows out of the mold onto the newly exposed mold inner surface to facilitate the ejection of the molten model material. This makes it easier to discharge the model material on the surface.

The present invention has one or more consumable models therein, may have any mold wall thickness, and is other of a refractory metal casting mold that may or may not be supported by an external particulate medium surrounding the mold. Although not limited to practice to remove one or more consumable models from the form, the method is particularly useful for removing one or more consumable models from the interior of a gas permeable "lost wax" precision cast ceramic cell mold. When steam is used as the preferred condensable vapor, the present invention contains conventional waxy models or other model materials that melt at temperatures below the boiling point of water (eg, about 212 ° F.) under certain ambient atmospheric conditions imparted during the model removal operation. Can be implemented to remove one or more consumable models that may be.

In accordance with another embodiment of the present invention described below, a conventional wax figure or other that melts at temperatures above the boiling point of water using superatmospheric pressure steam for this purpose during the model removal operation. Another embodiment of the invention may also be practiced to remove one or more consumable models that may contain model materials. Moreover, other embodiments of the present invention may be practiced using subatmospheric pressure steam to remove one or more consumable models that may require lower temperatures to melt the consumable models.

Optionally, in the practice of the present invention, steam may be provided by any other suitable material, such as condensable vapor of mineral spirit having a boiling point of about 300 ° F., for example, but not limited to the content thereof. It can be replaced, where the steam can be condensed and provide heat to the consumable model when it comes in contact with the model for the purpose of melt melting the model.

For the purpose of illustration and not of limitation, embodiments of the present invention are described in terms of the respective gates for the central hollow slugging holes 30 of the master assembly 40 in the interior of the "lost wax" precision casting cell mold 20. The removal of the some wax figure 10 joined by 35 is demonstrated below with reference to FIGS. In Fig. 1, the hollow molten iron 30 has an inner chamber 30a extending along an axis and bonded to the outer surface 30s by wax welding or fastening techniques. And preformed wax sprues that hold. For the purpose of illustration, the wax spouts 30 may be preformed so as to have an internal chamber 30a, in which the wax sputters are heated by melting, extruding, and heating the mandrel. This allows the solid wax tang to be drilled, or any other suitable technique, by initially forming a tang in a cylindrical or other shaped mandrel that will be sequentially removed by heating adjacent wax that physically evicts the mandrel. Can be preformed.

Although two models 10 are shown in FIG. 1, one skilled in the art will appreciate that additional models 10 are generally joined around the sprue 30 at the same location as the model 10, but are shown in cross section. You will understand that Esau is not visible. In addition, an additional model 10 may be joined via a gate to another axis region (eg, on top of model 10 shown in FIG. 1) along the length of its axis around the sprue 30, which is known in the art. Method and its teachings are shown in US Pat. No. 5,069,271, incorporated herein by reference.

Referring to Figure 1, the "lost wax" precision casting cell mold 20 is a central wax in a conventional "lost wax" method for producing a cell mold, for example as described in US Pat. No. 5,069,271. Appears attached to a plurality of wax masters 10 joined by gates 35 around the sprues 30, including a master 10 bonded to the hollow tuyeres 30 by gates 35. The master assembly 40 is repeatedly dipped into a refractory slurry with a binder, plastered with coarse refractory plaster particles, and dried to build a cell mold on the master assembly. The patent describes a gas permeable thin wall cell mold with a mold wall thickness of about 1/8 inch or less. The mold 20 with such a thin mold wall as described in the above patent is applied to the casting vessel 60 by the particulate support medium 50 (e.g., ceramic particulate) as shown in FIG. Can be supported at The invention is not limited to being implemented with such thin walled cell molds supported by particulate media surrounding the cell mold, but instead, as shown in FIG. 1, whether the outside is supported by particulate support media Regardless, it can be implemented with fire resistant molds with any mold wall thickness.

The cell mold 20 is shown inverted (eg, turned upside down) such that the model material and condensed steam melted by gravity are discharged from the lower end of the spout 30. The mold 20 is one in which the discharge of the molten master material and the condensation steam from the mold can be easily positioned in different orientations. In addition, the mold 20 may be moved during a model removal operation that facilitates the discharge of the molten model material and condensation steam out of the mold.

Referring to FIG. 1, the steam discharge tube 100 is located in the elongated chamber 30a of the hollow tuyeres 30 of the model assembly 40, and thus inside the hollow tuyeres 30 of the model assembly 40. At a substantial atmospheric pressure to release a stream of steam (indicated by arrow “SF”) therein (indicated by arrow “A”) to contact and melt the wax master assembly, while the outside of mold 20 The surface 20s is substantially under air pressure (represented as "ambient pressure") of the ambient atmosphere. In FIG. 1, the non-condensable gas atmosphere forming ambient air around the mold 20 may be at ambient temperature or cooled relative to ambient temperature. A typical wax material that is the raw material for model assembly 40 melts at about 180 [deg.] F. (non-limiting example described for illustrative purposes) and becomes a virtual fluid.

Steam at substantial atmospheric pressure occurs at steam source 110, which includes a conventional steam generator sold as Model LB240 by Electro Steam Generator Corp. The steam flows from the steam generator or source 110 through the supply pipe 120 to the steam discharge pipe 100. Steam flow from the source or generator 110 may be assisted by adjusting the pressure in the steam generator such that adequate steam flows through the mold to replace the amount of condensed steam.

Surfactant SF is introduced into steam discharge tube 100 through surfactant supply conduit 101 connected to surfactant supply pump 111. The pump 111 pumps out the surfactant from the supply tank T and sends it out. Typically the surfactant in tank T is in diluted form. The surfactant is diluted to a concentration selected, for example, in the liquid carrier medium. The flow of surfactant (SF) in conduit 101 is controlled using surfactant metering pump 111 or valve equipment to control the flow rate of surfactant from the appropriate surfactant feed pump. For example, alternative apparatuses and methods for introducing surfactant (SF) into tube 100 may be provided to the tube 100 using a regulating valve and supplying a liquid surfactant to the control valve at a constant pressure. Adjusting the flow of the thin surfactant.

Although surfactant (SF) has been described as being introduced to the internal steam of the discharge tube 100, the present invention is not limited to this fact. For example, the surfactant may be introduced to the outside of the steam discharge tube 100 using the second surfactant discharge tube 100 ′ as shown in FIG. 1A. Surfactant discharge tube 100 ′ extends into the mold to allow surfactant SF to flow downstream of the end of steam discharge tube 100 to allow discharge tube 100 within the mold as shown in FIG. 1A. In the steam stream after it has been discharged at the end.

By way of example, and not by way of limitation in the context of the description, the exemplary surfactants used to practice this aspect of the invention include Tomadol Grade 1-5 nonionic alcohol ethoxylate liquid surfactants, Such liquid surfactants, available from Tomah Products, Inc., Milton, WI, are diluted in a 0.5% by weight solution in water (carrier medium) and 60 ml in a steam stream in the discharge tube 100 through conduit 101. It is added at the rate of / min. The surfactant is added to the discharge tube 100 so that the refractory mold walls will melt and expose while the wax model is subjected to a model removal operation and will be given steam inside the mold.

The invention is not limited to the practice of the surfactants of the examples described above, as different nonionic surfactants can be used in different concentrations in steam or condensable vapor. In general, the surfactant and its concentration in the condensable vapor are selected to lower the surface tension of the condensate vapor in contact with the consumable model inside the mold, so that the molten model material flows more easily over the inner surface of the newly exposed mold, Emissions of the molten model material are improved off leaving little residual model material on the mold surface.

In addition, if the condensable vapor contains steam, water has been described as described above as a carrier medium for the surfactant, but the present invention is not limited to this fact. Such surfactants are those that can be delivered in diluted form using any liquid mediator that can coexist with the particular non-aqueous condensable vapor used. For example, if the condensable vapor contains mineral spirits, the carrier medium may contain mineral spirits.

At substantial atmospheric pressure steam containing surfactant (SF) is released into chamber 30a at a sufficiently high flow rate to retire air in chamber 30a, and gradually the model material of wax tug 30 and subsequent gate 35 ) And the model 10 to melt it. The flow rate of steam discharged into the chamber 30a may vary during removal of the spouts and the model according to the condensation rate of the steam in the mold. This rate will depend on the size of the mold and the surface area of the wax at the point of exposure to steam during de-waxing. When a model consisting of a composite row and a gate are joined to the sprue along its length, steam proceeds towards the gate and the model in sequence to uniformly and gradually melt the model material of each model.

In the practice of the present invention, the wax spouts 30 may be present or may be removed in other ways prior to the removal of the model 10 in contact with steam. That is, if only the model 10 is present in the cell mold 2 with an empty central spherical passageway, the steam discharge tube 100 discharges steam inside the mold to connect the model 10 and any gate 35 connected to the model. ) To contact and melt it.

2 and 4 show the process of removing the model after the central hollow tuyeres 30 are melted and removed and while the gate 35 and the model 10 are melted and removed. The steam containing the surfactant condenses where the wax-like material is melted, so it can be seen that the steam is directed to the gate 35 and the model 10 associated with the gate. Specifically, as steam condenses on the surface of the gate and model, a relatively low pressure is generated in the region V closest to where the gate and / or model material melts and flows towards the region of the molten gate and model. Causes new downstream steam. The molten liquid wax material is partially absorbed by the inner mold wall surface as indicated by the surface area S and acts as a barrier to prevent steam condensate from being absorbed through the thickness of the mold wall W. Moreover, the presence of ambient air pressure on the outer surface 20s of the mold 20 does not provide the driving force to cause steam condensation through the mold wall, thereby preventing the mold wall from saturating with the steam condensate and It prevents adverse effects when a binder is present in the wall. During the work of removing the model, the outer surface 20s of the mold exposed to ambient air (as a non-condensable gas atmosphere) is consequently kept dry (no liquid water). The pressure difference between the condensable vapor inside the mold 20 and the non-condensable gas atmosphere outside of the mold 20 is such that the condensable gas exits the outside surface of the mold through the gas permeable mold wall W; It is small enough to prevent the non-condensable gas from entering the mold cavity filled by the consumable model assembly being removed through the wall W. The condensable vapor inside the mold and the non-condensable gas atmosphere outside the mold are present at substantially the same pressure for this purpose.

In FIG. 4, the contents of the surfactant with condensable vapor (eg, atmospheric steam) are condensate along the surface of the wax absorbing refractory mold and the wax absorbing refractory wall, in the state of wet steam condensate. Resulting in a surface layer formation. Thus, because the molten wax model material exiting the molten model zone has low viscosity, the molten wax flows on the steam condensate layer where it is easier to flow out of the mold cavity along the mold wall. This fact allows for faster removal of the model material from the mold cavity and little wax model material remaining in the mold cavity.

In addition to the description of FIG. 4, the steam condensate and the molten wax model material are discharged out of the mold 20 by gravity through the passage P created when the hot water space or the hollow wax water spout 30 is removed. The molten wax model material is collected on or in a collection tray or vessel (not shown) located under the mold 20 of FIG. The axis of the mold 20 of FIG. 2, including the consumable model, such as the longitudinal axis L of the mold 20, may be inclined with respect to the direction of gravity while the consumable model is melted or after the consumable model is melted. have.

Steam at substantial atmospheric pressure is believed to produce only a small thermally affected zone (Z) in the wax model such that the remaining non-melted portion of the solid wax model 10 is relatively unaffected by steam. In this regard, Applicants do not intend to adhere to any theory. These small zones that receive heat but do not melt the model material are free from thermal expansion with respect to the molten surface, thus resulting in little or no pressure on the enclosing fire resistant mold. Thermal expansion of the wax inside the mold causes the mold to crack during standard autoclave de-waxing operations.

The release of steam and surfactant (SF) from the steam discharge tube 100 into the mold is performed by melting the entire model assembly 40 (including the hollow spout 30 and the model 10) and removing it from the mold 20. It continues until it leaves, and leaves the empty cell mold 20 including the plurality of mold cavities MC connected to the tap opening passage P as shown in FIG. The mold is then prepared for heating at an appropriate heating temperature to prepare the mold for containing the molten metal or alloy to be cast in the mold, a procedure well known and not within the scope of the present invention.

Although the chamber 30a of the hollow tuyeres 30 has been described above in relation to FIGS. 1 to 4, the present invention is not limited thereto. As shown in FIG. 5, in FIG. 5, steam exiting the tube 100 and released under atmospheric pressure containing a surfactant from the tube 101 is exposed at the exposed end 30e 'of the solid bath 30'. By moving the discharge tube 100 in a relatively axial direction to impinge and gradually melt the chamber 30a 'as it is in the solid precursor spout 30'. It may be formed in the precursor sputter 30 'as it is. After the chamber 30a 'is formed, the removal of the current hollow spout 30' and the model 10 can be performed as described above in connection with Figures 1-4. In Fig. 5, like features of Figs. 1 to 4 are denoted by like reference numerals.

In another embodiment of the invention shown in FIG. 6, a thin wall mold or other fire resistant mold 20 supported or surrounded by a particulate support medium 50 in a casting vessel 60 as described in US Pat. No. 5,069,271. At the consumable model assembly 40 is removed. The particulate medium 50 may contain ceramic particles or grog as described in the patent. Removal of the model releases steam from the steam discharge tube 100 inside the hollow spout 30 of the model assembly 40 under substantial atmospheric pressure as described in connection with FIGS. 1-4 and exits the tube 101. It is carried out by contacting and melting the hollow tuyeres 30 containing the surfactant and then contacting and dissolving them in the model. The outer surface 20s of the mold 20 is substantially surrounded by a vent-to-atmosphere 61 in contact with the particulate medium 50 and directed to the atmosphere on the casting vessel 60 during model removal. It is placed under atmospheric pressure. The outer surface 20s of the mold and the particulate medium 50 have the molten wax partially absorbed into the mold wall W and the steam condensate to reduce the thickness of the mold wall as described above with reference to FIGS. As a result, they are kept dry (no liquid water).

An embodiment of another method of the present invention shown in FIG. 7 described for the purpose of further describing the present invention, without limiting the technical content, is described below. Here, a plurality of waxes, which are released above the atmospheric pressure or below the atmospheric pressure, are released into the mold and bonded to the central hollow spout 230 by each gate 235 inside the " lost wax " precision casting cell mold 220. Remove the model assembly 240 with the model 210. While the outer surface of the mold is placed in non-condensable gas at pressures substantially higher than the same atmospheric pressure, using steam at pressures above atmospheric pressure not only allows melting at higher melting points of the model material but also unit volume of steam. It also increases the heat capacity of sugar. Using steam at sub-atmospheric pressure allows melting and removal of model materials requiring lower temperatures, for example, while the outside of the mold is placed under a non-condensable gas atmosphere at pressures substantially below the atmospheric pressure. The method embodiment according to this fact is that the method embodiment can alternatively be used in place of steam at a pressure lower than atmospheric pressure, but the following method embodiment shows that steam at a pressure higher than atmospheric pressure containing surfactant (SF) Will be described.

The mold 220 is placed inside the pressure vessel 250 and above the collecting vessel 252 for collecting and containing molten wax and steam condensate leaving the mold during the model removal operation. The pressure vessel 250 may comprise a casting vessel in the form of a particulate support medium around the mold 220 as shown in FIG. Optionally, the pressure vessel 250 may be free of particulate support media, for example only the cell mold may be present and empty. The pressure vessel 250 may be formed of a suitable pressure resistant material, such as steel, and may consist of a typical conventional pressure vessel. As shown in FIG. 6, the casting chamber 60 and the mold contained therein may also be located inside a separate pressure vessel 250 for a de-waxing step of pressure above atmospheric pressure.

A seal 254 is provided between the mold 220 and the wall 250a of the pressure vessel to substantially prevent gas mixing from the interior region of the seal 254 to the exterior of the seal 254. do. Seal 254 may include a steel tubular member with rubber or other form of seal 254a to seal mold 220.

At pressures above atmospheric pressure, the steam containing surfactant from tube 101 is released into mold 220 in discharge tube 300. The pipe 300 is connected to a source S of steam at a pressure higher than atmospheric pressure, such as the steam generator described above, extending through a hole in the wall 250a and forming a surfactant as shown in FIG. Also connected to input conduit 101. Simultaneously with the release of steam above atmospheric pressure inside the mold 220, air pressure at a pressure substantially equal to the steam pressure is provided to the pressure vessel 250 through the inlet 255. Inlet 255 is connected to a source of compressed air, such as an air compressor (eg, Kaeser model SP25 compressor), for air pressure above atmospheric pressure. Thus, an embodiment of the present method involves steam containing surfactant in the tube 101 inside the mold 220 while the outside of the mold 220 is placed under a steam-free gas atmosphere outside the mold. Releasing and contacting the model material and thereby melting the model material, where the steam inside the mold and the no-steam atmosphere outside the mold are at substantially the same pressure. The pressure of steam and the corresponding air (or other gas) may be adjusted to any pressure (and thus temperature) suitable for rapid melting of the model material.

Pressures higher than atmospheric pressure inside the pressure vessel may be provided by gases other than air, such as nitrogen, inert gases or gases at a pressure higher than the desired atmospheric pressure, which is substantially the same as the steam pressure inside the mold.

An air discharge valve 256 is provided in the wall of the pressure vessel to discharge air that originally existed inside the mold 220 and remain in the interior region of the seal 254 originating from the region inside the seal 254. 250).

The model removal operation according to the embodiment of FIG. 7 proceeds as described above in connection with the release atmospheric pressure steam with surfactant inside the mold 20, where steam above atmospheric pressure is a solid wax material of the model assembly. In condensation. Since steam at a pressure above atmospheric pressure is at a higher temperature upon compression, more heat is transferred to the wax surface in embodiments of the present invention. When the steam condenses, a slightly reduced pressure is formed, which induces more steam in contact with the wax surface to facilitate the model removal operation. Molten wax and steam condensate from the wax surface flows from the mold cavity into the wax and condensate collection dish 252. The de-wax operation only occurs internally within the mold 220 in an orderly fashion from the spout 230 to the gate 235, and then in the wax model 210. The pressure vessel seal 254 for the mold results in no steam being applied to the outer surface of the mold 220 in the pressure vessel 250. Thereby, the steam-free circumference is given to the pressure vessel 250.

8 to 12, an additional aspect of the present invention will be described. Unsupported cell mold 500 (FIG. 10), with or without surfactants contained in steam or other condensable vapor, removes the model using steam or other condensable vapor in the manner described above. During the process there is a combination of rotation and tilting against gravity. This embodiment is not limited to the operation of removing the model using steam or other condensable steam. This embodiment may contemplate using different model removal techniques while the mold is under a combination of rotation and tilting motions. For example, a hot air or gas stream can be introduced into the mold by heating and melting the mold while under the rotating and tilting motions in which the mold is coupled. The mold may also be placed in a furnace to freshly heat the model while under the combined rotational and tilting motion. In addition, a chemical dissolution medium may be introduced into the mold to dissolve in contact with the model while undergoing combined rotation and tilting of the mold.

Similarly, this additional aspect of the present invention is directed to one or more consumable models from a mold that is externally supported by a particulate medium enclosed in a casting vessel described above in connection with FIG. 6 and also described in US Pat. No. 5,069,271. It is to remove the action.

In FIG. 10, the non-supported cell mold 500 is shown with a number of consumable (eg wax) models 510 located along the length of the consumable (eg wax) ball 530. Each model is represented by a gate 535 connected to the sprue. According to this aspect of the invention, as shown in FIG. 10, the rotational movement about the longitudinal axis L of the mold during the tilting motion with respect to gravity is carried out at the center when removing the model and the ball material. The uniformly molten model material is discharged from all the mold cavities MC arranged around the tuyeres passage P.

Figure 8 illustrates an apparatus for implementing this aspect of the invention before the mold 500 is installed in the apparatus. 9 shows the apparatus before the mold 500 is installed in the apparatus and before the mold tilts against gravity. Figure 10 shows the device after the mold has been in place and the longitudinal axis L has been tilted against gravity such that the longitudinal axis L is inclined at a certain inclination angle.

In one embodiment of this aspect, the mold 500 with consumable model and spout is installed between the upper mold clamp and rotation mechanism 510 and the lower mold support mechanism 512. The cell mold 500 has an upper annular collar 500c that receives the end 510e of the upper mold clamp mechanism 510 as best shown in FIG. The end 510e closes the mold pouring hole P. As shown in FIG. The mold has a lower annular collar 500d housed in a rotatable nest 512n located on a support plate 512p of the mold support base 512b as best seen in FIGS. 10 and 11. do. The mold support base 512b is secured to the frame F side arm A of the device. A cross brace plate P3 is installed between the arms A. The mold collars 500c and 500d may be integrally formed with the mold 500 or may be separately formed and attached to the mold 500.

An end of the steam supply tube 600 extends upwardly through a hole in the mold support base 512b and the support plate 512p to help introduce steam or other condensable vapor into the mold 500. In communication with the open lower end of the mold 500 shown in FIG. The tube 600 is in a fixed position on the mold support base 512b using the clamp 513 as shown in FIG. The tube 600 is connected using a flexible or rigid conduit suitable for a steam generator, such as the steam generator 110 described above with reference to FIGS.

The mold support plate 512p has a rotary wheel 512f spaced apart from the circumference of the first set (three shown) for rotatably supporting the outer circumference of the rotary nest 512n. In addition, the mold support plate 512p also has a rotary wheel 512g in which the circumference of the second set (three cities) in which the closed plate 512s of the rotary nest 512n is supported to rotate thereon is also separated. Have Thus, the rotary nest 512n is supported laterally by the wheel 512f and is supported from below by the wheel 512g which rotates about the lower mold support base 512.

Each wheel 512f is supported by a bearing (not shown) on the upright stud S1 mounted on the flat plate 512p. Each wheel 512g is supported by bearings (not shown) on the side studs S2 mounted on the support plate 512p.

As shown in Fig. 10, the rotary nest 512n has a substantially cylindrical concave portion R facing upward, which has a structure for accommodating the collar 500d of the mold 500.

The mold clamp and rotation mechanism 510 have a shaft 510s having an end 510e that frictionally engages the collar 500c of the mold 500. For the purpose of frictional engagement, the end 510e is made of rubber or other material to achieve a frictional engagement with the mold collar 500c in which a rotational motion is transmitted to the mold by the rotation of the shaft 510s.

The shaft 510s is rotated with the upper sprocket 510f which is drive-coupled with the drive chain 510c. The chain is driven by an output sprocket 513s of a conventional gear reducer GR1 driven by a conventional electric or hydraulic motor M1, which motor is arranged on the horizontal fixed plate P1 of the frame F. The shaft 510s is rotatably supported by a bearing block 510b attached to a vertically fixed frame plate P2 fixed to the frame plate P1. In this structure, the mold 500 fixed between the mold clamp and the rotation mechanism 510 and the mold support mechanism 512 is rotated by the shaft 510s.

The mold clamp and rotation mechanism 510 is formed by a sliding support shaft 700s guided by a pair of bearings 700b at the lower end to the fixed housing H1 and at the upper end to the fixed housing H2. 512 may be moved upward and downward. An air cylinder (not shown) may cause the mechanism 510 (e.g., shafts) to lower the mechanism 510 to hold the mold in place and to raise the mechanism 510 so that the mold can be placed on the device. 700 s)) and the frame 512 (eg, plate P3). When the air cylinder is in the raised position, the non-rotating shaft 800s exits the non-rotating guide tube 800t to cause the mechanism 510 to rotate sideways on the way to easily load a new mold into the device.

The main shaft 550 is rotatably mounted on the frame F by the bearing block 552, so that it is rotatable or pivotal about its longitudinal axis, the axis being the length of the mold 500. Perpendicular to the direction axis. A rectangular cross section support sleeve 553 is fixed in the same manner as welding on the sleeve and the rotating shaft 550. The frame arm A with the mold support mechanism 512 is fixed to the sleeve 553 in the same manner as welding, so as to rotate or pivot with the shaft 550. The mold clamp and rotation mechanism 510 are secured to the sleeve 553 by the shaft 550, the non-rotating shaft 800s, and the air cylinder. Thus, the mold clamp and rotation mechanism 510 and the mold support mechanism 512 are mounted on the sleeve 553 so that they rotate or pivot with the shaft 550.

The shaft 550 rotates or pivots with a conventional electric drive motor M2 connected to the end of the shaft 550 via the gear reducer GR2. The gear reducer GR2 is connected to the machine frame 512 by an interaction linkage L ', which causes the gear reducer to maintain rotational motion with the shaft. The drive motor may be of a stepping motor type. Thus, the drive motor M2 can rotate or pivotally move the shaft 550 incrementally or continuously about the longitudinal axis. In this manner, the mold 500 fixed between the mold clamp and rotation mechanism 510 and the mold support mechanism 512 can be tilted against gravity as shown in FIG. 10 while the mold is being rotated.

In operation of the apparatus, the mold 500 with the consumable model and the spout is placed on the rotary nest 512n with the lower collar 500d received in the recess R of the rotary nest 512n. Next, the end clamp 510e of the shaft 510s of the mold clamp and the rotation mechanism 510 is lowered to engage the end 510e with the upper collar 500c of the mold 500 so that the rotation of the shaft 510s is performed. Pass the rotation on.

Initiate steam flow to conduit 600. The steam flow is introduced into the mold through the tube (600). The steam may contain the surfactant (FS) described above with respect to FIGS. 1-4 or the surfactant may be omitted depending on the optional model removal situation. The main shaft 550 pivots and inclines the mold clamp and rotation mechanism 510 and the mold support mechanism 512 to the desired desired angle of inclination with respect to gravity as shown in FIG. 10 and thus the mold 500. It tilts. The mold tilt angle and the mold rotation speed can be adjusted to the extent that it takes to discharge the molten wax from the mold cavity MC. In this way the wax can be evenly discharged in all mold cavities MC arranged around the central spout P. Thus, this aspect of the invention allows the wax to be evenly discharged from the mold cavity and the approximate volume of the mold cavity is below the gate G level when the mold is in the vertical position. Molten wax is discharged from the bottom of the mold and trapped in a pan (not shown).

The mold 500 may be rotated while the mold is inclined at a fixed angle with respect to gravity and kept inclined. Optionally, the mold may be tilted in such a way that the tilt increases at a selected tilt angle while the mold is rotated at each tilt angle, or may be tilted continuously. In addition, the mold can be continuously tilted while rotating continuously or intermittently. The implementation of the method depends on the form of the de-waxing model. Typically, a vertical non-rotating mold de-waxing operation is started and then changed to an inclined mold rotary de-waxing operation as a de-waxing treatment towards the mold portion draped under the gate hole. The mold tilt angle, rotation speed and time duration depend on the form of the de-waxed model.

Although this aspect of the present invention uses the steam or other condensable steam to heat and melt the model and the sprue, steam or other condensable steam may not It is introduced into the mold 500 through the tube 600 to heat and melt the consumable model and the spout. For example, a hot air or gas stream is introduced into the mold by heating and melting the mold while the mold is subjected to a combined action of rotation and inclination. The mold may also be placed in a furnace for freshly heating the model while the mold is undergoing a combination of rotation and tilting motions. In addition, a chemical dissolution medium may be introduced into the mold to dissolve in contact with the model while the mold undergoes a combined rotation and tilting operation.

The present invention is advantageous for removing one or more consumable models from a metal casting fire resistant mold, wherein the mold may have a wall thickness of any mold and may or may not be supported by the outer particulate medium surrounding the mold. It may be. The present invention is additionally beneficial for removing one or more consumable models while preventing saturation of the walls of the mold with steam condensate. The present invention can be practiced to reduce the cracking of the mold while removing the model and to make the thin-walled mold available without the cracking of the mold.

It is to be understood that the present invention is not limited to the above-described embodiments, but may be modified and modified without departing from the spirit of the appended claims.

1 is a drawing of a consumable model to be removed in accordance with an embodiment for explaining the present invention by releasing atmospheric pressure steam containing a surfactant from a discharge tube shown and positioned in a hollow spout of a model assembly present inside a mold. Is a schematic illustration of a fire resistant casting mold.

FIG. 1A is a drawing of a consumable model to be removed in accordance with another illustrative embodiment of the present invention by releasing surfactant and atmospheric pressure from a split discharge tube positioned within a hollow spout of a model assembly present inside the mold. Is a schematic illustration of a fire resistant casting mold.

FIG. 2 is a schematic representation of the refractory casting mold of FIG. 1 with a hollow spout of a consumable model assembly already removed by melting, and respective gates and models to be melted and removed.

FIG. 3 is a view similar to FIG. 2 showing the state after the model has been completely removed from the cell mold.

4 is an enlarged view of each model of FIG.

FIG. 5 is a view similar to that of FIG. 1, but showing a model assembly having a solid taphole where the steam discharge tube moves to a solid taphole and forms a hollow taphole as it is.

Figure 6 is a schematic illustration of a refractory cast mold having a consumable model to be removed, in accordance with another illustrative embodiment of the present invention, wherein the mold is supported on its outer surface by a particulate support medium surrounding its surroundings.

FIG. 7 is similar to FIG. 1 and is removed in accordance with another embodiment of the present invention by discharging steam from a steam discharge tube, which is shown as located within the hollow spout of the model assembly present in the mold at pressures above or below atmospheric pressure. A diagram of a fire resistant casting mold having a consumable model to be used.

8 is a perspective view of an apparatus for receiving a mold from rotation and tilting during a model removal process according to another embodiment of the present invention.

9 is an elevational view of a partial section of the device of FIG.

FIG. 10 is a view similar to FIG. 9 showing a mold tilted against gravity;

11 is an enlarged perspective view of an upper portion of a mold support for rotatably supporting a lower end of a mold.

12 is an enlarged perspective view of the lower part of the mold support for rotatably supporting the mold end;

Claims (37)

In a method of removing a fugitive pattern inside a fire resistant mold, the method comprises: Introducing condensable vapor and surfactant into the mold to melt in contact with the model material; Condensing the condensable vapor in the interior of the mold, which is in contact with the mold and melted; Evacuating the molten master material and the condensed vapor in the mold; A method for removing a consumable model in a fire resistant mold, characterized by using the surfactant to promote the discharge operation. A method of removing a consumable model inside a fire resistant mold, the method comprising: Introducing the condensable vapor and the surfactant into the mold such that the model material is in contact and melted, while leaving the outside of the mold under a non-condensable gas atmosphere outside the mold; Condensing the condensable vapor inside a mold where condensable vapor contacts the mold and melts the mold while maintaining the exterior of the mold free of condensed vapor; Evacuating the molten master material and the condensed vapor out of the mold; A method for removing a consumable model in a fire resistant mold, characterized by using the surfactant to promote the discharge operation. The method of claim 2, wherein the type and amount of surfactant is selected to reduce surface tension between the condensable vapor and the model material. 3. The method of claim 2, wherein the condensable vapor is steam. 3. The method of claim 2, wherein the model material is wax with or without a non-wax filler. 3. The method of claim 2, wherein the surfactant is added to the condensable vapor before the condensable vapor exits the discharge tube and enters the mold. 3. The method of claim 2, wherein the surfactant is added to the condensable vapor after the condensable vapor exits the discharge tube and enters the mold. 8. The method of claim 7, wherein the surfactant is added to the condensable vapor stream in dilute form using a medium that can coexist with the condensable vapor used. The mold of claim 2 wherein the pressure difference between the condensable vapor inside the mold and the non-condensable gas atmosphere outside the mold prevents condensable gas from escaping outside the mold and the non-condensable gas is in the mold. A method of removing a consumable model within a fire resistant mold, characterized by small enough to prevent entry into the cavity. 3. The method of claim 2, wherein the condensable gas and the non-condensable gas atmosphere are at substantially the same pressure. 4. 3. The method of claim 2, wherein the condensable vapor comprises steam. 3. The method of claim 2, wherein the non-condensable gas is air. 3. The method of claim 2, wherein the condensable vapor is supplied from a source to a discharge tube and condensable vapor is discharged from the discharge tube into a mold. 3. The method of claim 2, wherein the condensable vapor is released inside the mold at atmospheric pressure. 3. The method of claim 2, wherein the condensable vapor is released into the mold at a superatmospheric or subatmospheric pressure, and the non-condensable gas is at a pressure that is substantially above or below atmospheric pressure. A method for removing a consumable model within a fire resistant mold, characterized in that it is provided outside of the mold in a container provided with the mold. 16. The method of claim 15, comprising using a seal between the mold and the container to prevent condensable vapor from entering the outside of the container of the mold. . The method of claim 2 wherein the consumable model contains wax. 3. The axis of a mold having a consumable model is inclined with respect to the direction of gravity while the consumable model is melted or after the consumable model is melted and the mold is rotated about a second axis. How to remove consumable models from fire resistant molds. 3. The method of claim 2 including the step of initially releasing condensable vapor inside a hollow sprue of the model. 20. The method of claim 19, wherein the hollow tuyeres are preformed in the consumable model prior to the release of condensable vapor. 21. The method of claim 20, wherein the hollow tuyeres are formed by condensable vapor released against the exposed end of the solid tuyeres. 3. The method of claim 2 wherein the exterior of the mold is surrounded by a support particulate medium in the container. 3. The method of claim 2 wherein the exterior of the mold is not surrounded by a support particulate medium. An apparatus for removing a consumable model inside a fire resistant mold, the apparatus comprising: Means for introducing an atmospheric pressure, a pressure above atmospheric pressure, or a pressure below atmospheric pressure into the mold to melt in contact with the model material; And a means for providing a surfactant to the condensable vapor. 25. The apparatus of claim 24, wherein the means for introducing the condensable vapor includes a discharge tube in communication with the interior of the mold. 25. The apparatus of claim 24, comprising a surfactant supply conduit for supplying the surfactant to the discharge tube. 25. An apparatus according to claim 24, comprising a surfactant discharge tube which introduces a surfactant with condensable vapor after it is released from the discharge tube. In a method of removing a consumable model inside a fire resistant mold, the method comprises: Melting or melting the consumable model; Subjecting the mold to rotation and tilting to facilitate the ejection of the model material from the mold. 29. The method of claim 28, wherein the mold rotates about the longitudinal axis while the longitudinal axis is tilted with respect to gravity. 29. The method of claim 28, wherein the fire resistant mold comprises a cell mold. 31. The method of claim 30, wherein the cell mold is not surrounded by particulate support media. 31. The method of claim 30, wherein the cell mold is surrounded by a particulate medium. 29. The method of claim 28, wherein the consumable model is melted by introducing steam or condensable vapor into the mold. An apparatus for removing a consumable model inside a fire resistant mold, the apparatus comprising: A mold clamp and rotation mechanism and a mold support mechanism, wherein the mold is disposed therebetween; A pivotable shaft on which the mold clamp and rotation mechanism and the mold support mechanism are disposed; Means for pivoting the shaft against the gravity by tilting the mold clamp and rotation mechanism and the mold support mechanism; And a means for removing the consumable model. 35. The consumable mold of claim 34 wherein the mold clamp and rotation mechanism includes a rotary shaft having an end frictionally coupled with the end of the mold to transmit rotation to the shaft. Device. 35. The apparatus of claim 34, wherein the mold clamp and rotation mechanism are movable up and down relative to the mold such that the end engages with the mold. 36. The apparatus of claim 35, wherein the mold support mechanism includes a rotatable nest that receives the opposite end of the mold.

Images