Patent Application
20180111186
The present disclosure is related to methods and systems for casting metal, and more particularly to methods and systems for casting metal using a riser sleeve with an integral mold cavity vent.
Foundries produce metal castings using a casting process. The casting process is characterized by using mold material. A frame or mold box known as a flask contains the molding material. A foundryman creates mold cavities by compacting molding material around mold patterns within the flask. The metal casting is formed by filling the mold cavities with molten metal. Molten metal may shrink when cooling to form solid metal. Shrinkage may create voids in a metal casting. Voids may cause the solidified metal to become less structurally sound. Voids may further alter the solidified metal's shape to an unintended shape. To prevent the shrinkage, a reservoir known as a riser is built into the mold. Risers provide molten metal to the casting as it solidifies so that any voids form in the riser and not in the casting. As molten metal fills the mold cavity, gases may become trapped in the mold cavity. Gases in the mold cavity may create voids in the solidified metal.
The teachings of the present disclosure relate to a system and a method for casting metal using a vented riser sleeve. In accordance with one embodiment, a metal casting system includes a mold cavity and a vented riser sleeve. The vented riser sleeve includes a riser reservoir and a vent passage. The riser reservoir is fluidly connected to the mold cavity and configured to allow molten alloy to flow from the mold cavity to the vented riser sleeve. The vent passage extends through a length of the riser sleeve portion to allow airflow from the mold cavity through the vent passage.
According to another embodiment, a metal casting system includes a molding flask and a vented riser sleeve. The molding flask includes a drag mold portion comprising external and internal drag mold walls. The molding flask includes a cope mold portion comprising external and internal cope mold walls. The internal drag mold walls and internal cope mold walls form, at least in part, a mold pattern cavity representative of a mold pattern. The vented riser sleeve comprises a riser reservoir fluidly connected to the mold pattern cavity and configured to allow molten alloy to flow from the mold cavity to the vented riser sleeve. The vented riser sleeve comprises a vent passage that extends through a length of the vented riser sleeve to allow airflow from isolated spots in the mold cavity through the vent passage.
According to another embodiment, a method is provided for casting metal includes positioning a vented riser sleeve system within in a flask comprising a mold cavity, the vented riser sleeve extending at least from the flask to the mold cavity. The vented riser sleeve includes a riser reservoir fluidly connected to the mold pattern cavity and configured to allow molten alloy to flow from the mold cavity to the vented riser sleeve to create a casting portion. The vented riser sleeve includes a vent passage that extends through a length of the vented riser sleeve to allow airflow from the mold cavity through the vent passage. The method further includes removing the vented riser sleeve from the casting portion.
Certain embodiments may provide one or more technical advantages. In some embodiments, the vented portion of the riser sleeve allows evacuation of hot gasses that build up in isolated sections of a mold. A traditional method requires foundrymen to create a hole to evacuate the gas. For example, foundrymen may drill a hole through a mold cavity. The traditional method may be time and labor intensive. Further, the traditional method is subject to human error as foundrymen may forget to drill the hole. Another technical advantage of particular embodiments is ensuring a clean metal casting. In the traditional method, foundrymen may introduce debris in the mold when drilling the hole. Yet another technical advantage of particular embodiments is ensuring that the coordinates of a vent are consistently located across casting molds. This improves the consistency, quality, and reliability of metal castings created using the casting molds. The current disclosure contemplates a clean, pre-formed vent passage that allows gasses to escape the mold cavity.
Other technical advantages will be readily apparent to one of ordinary skill in the art from the following figures, descriptions, and claims. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some, or none of the enumerated advantages.
A more complete understanding of particular embodiments will be apparent from the detailed description taken in conjunction with the accompanying drawings in which:
Foundries produce metal castings using a casting process. The casting process is characterized by using mold material. A frame or mold box known as a flask contains the molding material. A foundryman creates mold cavities by compacting molding material around mold patterns within the flask. The metal casting is formed by filling the mold cavities with molten metal. Most metals shrink upon cooling. To prevent the shrinkage from creating voids in the metal casting, a reservoir known as a riser is built into the mold. Risers provide molten metal to the casting as it solidifies so that any voids form in the riser and not the casting.
As molten metal solidifies, gases may become trapped in the mold cavity. Gases in the mold cavity may create voids in the solidified metal. Voids may cause the solidified metal to become less structurally sound. Voids may further alter the solidified metal's shape to an unintended shape. Thus, gases are generally removed from the mold cavity during the casting process. In the traditional process, a foundryman creates a hole directly in the mold cavity. For example, a foundryman may drill a hole through the mold cavity. This process may be time and labor intensive. Further, this process is subject to human error. For example, a foundryman may forget to drill a hole or drill an incorrect hole. Additionally, drilling a hole may create debris of impurities in the metal casting. This disclosure contemplates utilizing a vented riser sleeve to efficiently allow gas to escape the molding cavity while creating a clean metal casting.
Metal casting system 10 also includes a sprue 20 and a vented riser sleeve 100. Sprue 20 is a passageway through which a foundryman introduces molten alloy into mold cavity 16. One end of sprue 20 forms an opening in an external wall of flask 22, and another end connects to mold cavity 16. The cope and drag mold portions support sprue 20. Vented riser sleeve 100 insulates a riser reservoir 105. Riser reservoir 105 receives molten alloy after it flows through sprue 20 and mold cavity 16. A top end of riser reservoir 105 forms an opening in an external wall of flask 22. A bottom end of riser reservoir 105 connects to mold cavity 16. Vented riser sleeve 100 comprises a vent passage 110. Vent passage 110 generally allows air to from mold cavity 16 out of flask 22. Vent passage 110 may run throughout riser sleeve 100, from cavity to 16 to the outside of mold casting system 10.
When implementing particular embodiments of metal casting system 10, a foundryman packs molding material 18 around various patterns to form mold cavity 16 and sprue 20. The foundryman inserts riser sleeve 100 between mold cavity 16 and an external wall of flask 22. One of skill in the art would recognize that both the positioning and the number of passageways, such as sprues and riser reservoirs, may vary depending on various factors such as the mold pattern and the metal alloy used in a particular metal casting. The foundryman assembles flask 22 by coupling drag mold portion 14 to cope mold portion 12. The foundryman then pours molten alloy into sprue 20. The molten alloy flows through sprue 20 where it fills mold cavity 16 and riser reservoir 105. In some embodiments, the foundryman may pour molten alloy directly into riser reservoir 105. As the molten alloy solidifies and shrinks in mold cavity 16, molten alloy flows from riser reservoir 105 back into mold cavity 16 to compensate for shrinkage.
Particular embodiments may provide for more efficient solutions, for example, when evacuating air from mold cavity 16. Vented riser sleeve 100 comprises vent passage 110, which allows air to pass from mold cavity 16 out of flask 22. Because the foundryman is not drilling a hole near the riser sleeve 100, system 10 is less susceptible to human error. As another example, the preformed vent passage 110 reduces labor costs of manually drilling a hole in the flask 22. As yet another example, mold cavity 16 does not receive impurities caused by drilling.
A vented riser sleeve system may further comprise lip portion 115 which is part of vented riser sleeve 100. As illustrated, lip portion 115 of vented riser sleeve 100 extends to a portion of casting 120 that is higher relative to other portions of casting 120. Lip portion 115 may comprise vent passage 110. In some embodiments, vent passage 110 may not be in lip portion 115. Vent passage 110 may be located in any suitable location of vented riser sleeve 100. Generally, vent passage 110 allows air to escape from isolated areas of mold cavity 16. For example, as molten alloy solidifies, it may create air in mold cavity 16. For example, air pockets may form in mold cavity 16. Air pockets may create voids in casting 120, thus reducing the structural integrity of casting 120. Vent passage 110 may allow air to be released from mold cavity 16. In some embodiments, vent passage 110 is a preformed hole that extends throughout vented riser sleeve 100. Vent passage 110 may be any suitable shape. For example, vent passage 110 may be cylindrically shaped. As another example, vent passage 100 may be a rectangular shape.
As illustrated, vented riser sleeve 100 is connected to breaker 125. In some embodiments, breaker 125 reduces the section of metal that connects casting 120 to vented riser sleeve 100. Breaker 125 facilitates removal of vented riser sleeve 100 from casting 120. For example, breaker 125 may allow vented riser sleeve 100 to be removed from casting 120 by impacting vented riser sleeve 100 and/or casting 120. In some embodiments, breaker 125 is a Washburn core. In certain embodiments, system 100 may not comprise breaker 125. In these embodiments vented riser sleeve 100 may still be removed from casting 120. For example, vented riser sleeve 100 may be cut from casting 120, such as through a thermal cut from casting 120 with an oxy-acetylene torch.
Particular embodiments may provide for more efficient solutions, for example, when evacuating air from mold cavity 16. Vented riser sleeve comprises vent passage 110, which allows air to pass from mold cavity 16 out of flask 22. Because the foundryman is not drilling a hole near the riser sleeve 100, system 10 is not susceptible to human error. As another example, the preformed vent passage 110 reduces labor costs of manually drilling a hole in the flask 22. As yet another example, particular embodiments reduce manufacturing costs by reducing or eliminating expenses associated with replacing drill bits used to create holes high abrasion media. As yet another example, mold cavity 16 does not receive impurities caused by drilling.
Particular embodiments may provide for more efficient solutions, for example, when evacuating air from mold cavity 16. Vented riser sleeve comprises vent passage 110, which allows air to pass from mold cavity 16 out of flask 22. Because the foundryman is not drilling a hole near the riser sleeve 100, system 10 is not susceptible to human error. As another example, the preformed vent passage 110 reduces labor costs of manually drilling a hole in the flask 22. As yet another example, mold cavity 16 does not receive impurities caused by drilling.
At step 1210, the foundryman pours molten alloy into sprue 120 and/or riser reservoir 105. The molten alloy flows into mold cavity 16. As the molten alloy solidifies and shrinks in mold cavity 116, molten alloy flows from riser reservoir 105 back into mold cavity 16 to compensate for the shrinkage. As the molten alloy solidifies, air pockets may be formed in mold cavity 16. Vent passage 110 allows the air to escape mold cavity 16. The method is complete when the molten alloy has solidified to form casting 120. The foundryman removes vented riser sleeve 100 from casting 120 before the method ends.
Modifications, additions, or omissions may be made to the method described herein without departing from the scope of the present disclosure. For example, the steps may be combined, modified, or deleted where appropriate, and additional steps may be added. Additionally, the steps may be performed in any suitable order.
Although embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various other changes, substitutions, and alterations may be made hereto without departing from the spirit and scope of the invention as defined by the claims below. As another example, although particular steps have been described as being performed by a foundryman (e.g., pouring molten alloy, etc.) many of those steps may also be machine automated.
