Direct casting utilizing stack filtration

Abstract

A casting system includes a filtration assembly including a filter vessel housing spaced filters pre-heated to a temperature approximating a pouring temperature of molten material to be filtered to prevent breakage of the filter due to thermal shock from contact with the molten material. Preferably, an induction coil is used to inductively heat a susceptor adjacent the filter vessel or inductively heat filters which themselves serve as susceptors. Typically, the filter vessel is disposed below a pouring vessel and above a mold, pour cup and any sprue system used and is heated independently from the same. The filters are heated during pouring to facilitate flow of the molten material therethrough whereby very fine filters may be used. Spacing of the filters enhances flow control and allows a head of molten material to form whereby dross floats to the top of the head to prevent its entry into the mold.

1 . A method comprising the steps of: 
 pre-heating at least one filter to a filter temperature which will prevent breakage of the filter due to thermal shock from contact with molten material; and    passing molten material through the at least one filter.    
     
     
         2 . The method of  claim 1  wherein the step of pre-heating includes the step of pre-heating the at least one filter to a temperature which is within 75 degrees Fahrenheit of a pouring temperature of the molten material.  
     
     
         3 . The method of  claim 2  further including the steps of melting a metal or metal alloy to form the molten material; and heating the molten material to the pouring temperature.  
     
     
         4 . The method of  claim 1  further including the steps of heating a mold; and transferring a portion of the filtered molten material into the heated mold; and wherein the step of pre-heating includes pre-heating the at least one filter independently of heating the mold.  
     
     
         5 . The method of  claim 1  wherein the step of passing includes the step of passing molten material through the at least one filter which is disposed within a filter vessel and further including the step of transferring molten material from the filter vessel into at least one mold.  
     
     
         6 . The method of  claim 5  wherein the step of transferring includes the step of transferring molten material from the filter vessel into the at least one mold via a transferring assembly which is free of a filter.  
     
     
         7 . The method of  claim 1  further including the steps of covering a filter vessel which houses the at least one filter with a cover to facilitate the pre-heating of the at least one filter; moving at least a portion of the cover to create access to an entrance opening into the filter vessel; and pouring molten material through the entrance opening into the filter vessel.  
     
     
         8 . The method of  claim 1  wherein the step of pre-heating includes the step of heating a susceptor inductively and transferring heat from the susceptor to the at least one filter.  
     
     
         9 . The method of  claim 1  wherein the step of pre-heating includes the step of coupling an induction coil electromagnetically to the at least one filter to inductively heat the at least one filter directly.  
     
     
         10 . The method of  claim 1  wherein the step of pre-heating includes the step of pre-heating the at least one filter within a filter vessel to the filter temperature while the filter vessel is disposed in a pouring position for receiving the molten material from a pouring vessel.  
     
     
         11 . The method of  claim 1  further including the step of heating the at least one filter with a heat source other than the molten material during the step of passing to facilitate flow of the molten material through the at least one filter.  
     
     
         12 . A method comprising the steps of: 
 passing molten material through at least one filter disposed within a filter vessel;    heating the at least one filter with a heat source other than the molten material during the step of passing to facilitate flow of the molten material through the at least one filter; and    transferring filtered molten material from the filter vessel into a containing vessel.    
     
     
         13 . The method of  claim 12  further including the steps of melting a metal or metal alloy to form the molten material.  
     
     
         14 . The method of  claim 12  wherein the step of transferring includes the step of transferring molten material from the filter vessel into at least one mold via a transferring assembly which is free of a filter.  
     
     
         15 . The method of  claim 12  wherein the step of passing includes the step of passing molten material through two filters which are spaced from one another.  
     
     
         16 . The method of  claim 15  wherein the step of passing includes the step of passing molten material through two filters which are spaced from one another by a spacer disposed within the filter vessel between the two filters.  
     
     
         17 . The method of  claim 12  wherein the step of passing includes the step of passing molten material through at least one filter in such a manner to allow a head of molten material to form whereby dross floats to the top of the head of molten material.  
     
     
         18 . The method of  claim 17  wherein the step of transferring includes the step of transferring molten material and the dross out of the filter vessel so that molten material enters a mold and the dross remains in a structure intermediate the filter vessel and the mold.  
     
     
         19 . The method of  claim 12  wherein the step of passing includes the step of passing molten material through at least one preheated filter having at least twenty pores per inch.  
     
     
         20 . The method of  claim 12  further including the step of pre-heating the at least one filter to a filter temperature which will prevent breakage of the filter due to thermal shock from contact with the molten material.