Method and device for feeder head-poor or feeder head-free casting of hypoeutectic cast iron alloys

Abstract

A method and device for feeder head head-poor or feeder head-free casting of a component by means of a hypoeutectic cast iron melted mass includes providing a mold with a sprue, at least one gating and an overflow having a thermal module. The thermal module of the gating and overflow is below that of a region of the component having the largest thermal module. The gating and overflow are solidified before the region of the component having the largest thermal module. The mold is formed, such that it exerts pressure on the cast iron melted mass after solidifying of the gating and the overflow by means of a volume change in the direction of the enclosed cast iron melted mass, in such a way that reduction of the volume of the cast iron melted mass is compensated during solidifying.

1 . A method for feeder head-poor or feeder head-free casting of a component by means of a hypoeutectic cast iron melted mass, comprising the following steps: 
 providing a mold with at least one sprue, at least one gating and at least one overflow having a thermal module;    providing the thermal module of the gating and the overflow to be below that of a region of the component having the largest thermal module;    solidifying the gating and overflow before the region of the component having the largest thermal module; and    exerting a pressure on the cast iron melted mass with the mold after solidifying of the gating and the overflow by means of a volume change in the direction of the enclosed cast iron melted mass, in such a way that reduction of the volume of the cast iron melted mass is equalized during solidifying.    
   
   
       2 . The method of  claim 1 , wherein the volume change is effected, such that the mold has an inner mold, which expands under the heat effect of the enclosed cast iron melted mass, such that the volume of the inner mold increases on all sides, the inner mold can be compressed substantially less than it can expand under the heat effect, wherein the inner mold is surrounded by an outer mold, which allows an outward expansion of the inner mold only as far as necessary for compensation of a volume increase of the inner mold via the contraction of the cast iron melted mass.  
   
   
       3 . The method of  claim 2 , wherein the inner mold comprises a mold material containing at least one element that expands under the effect of heat.  
   
   
       4 . The method of  claim 3 , wherein the at least one element is the element with the largest volume share of the mold material.  
   
   
       5 . The method of  claim 2 , wherein the inner mold is a bonded sand mold.  
   
   
       6 . The method of  claim 1 , wherein the mold comprises an inner mold which reacts to the heating action from the cast iron melted mass in a volume neutral manner or with a minimal expansion or with a minimal contraction, wherein the inner mold is surrounded by a solid outer mold, wherein from the time point of the solidifying of the gating and overflow, a force is applied externally on the outer mold, wherein said force effects the volume change of the mold and compresses the entire contents of the outer mold; and wherein the force is applied until solidifying of the component.  
   
   
       7 . The method of  claim 6 , wherein the force applied on the outer mold is a static or dynamically increasing force.  
   
   
       8 . The method of  claim 1 , wherein the thermal module of the gating and the overflow is at least 30% below the largest thermal module of the component.  
   
   
       9 . The method of  claim 1 , wherein a cast iron melted mass is used, which solidifies hypoeutectically to cast iron with scaled graphite.  
   
   
       10 . The method of  claim 1 , wherein a cast iron melted mass is used, which solidifies hypoeutectically to cast iron with nodular graphite.  
   
   
       11 . The method of  claim 1 , wherein a cast iron melted mass is used, which solidifies hypoeutectically to cast iron with vermicular graphite.  
   
   
       12 . A device for feeding-poor or feeder headless casting of hypoeutectic cast iron melted mass, comprising: 
 a bonded sand mold having a gating and overflow, wherein the gating and overflow have a thermal module that is so far below the largest thermal module of the component that the gating and overflow solidify first, wherein the sand mold comprises a mold material that expands under a heat effect of the cast iron melted mass, and wherein the mold material itself is slightly less compressible under the heat effect of the cast iron melted mass than it is expanded under the heat effect;    an outer mold surrounding the sand mold, wherein the outer mold encompasses the sand mold on all sides and has free spaces for a sprue and overflow, wherein the outer mold is formed, such that it allows an outward expansion of the inner mold only as far as necessary for compensation of a volume increase of the inner mold via the contraction of the cast iron melted mass.    
   
   
       13 . The device of  claim 12 , wherein the mold material is a material mixture, wherein at least one of the materials contained in the mixture increases its volume under an effect of heat of the cast iron melted mass.  
   
   
       14 . The device of  claim 13 , wherein the at least one material that increases its volume comprises the largest portion of the mold material.  
   
   
       15 . The device of  claim 14 , wherein the at least one material that increases its volume is quartz sand.  
   
   
       16 . The device of  claim 12 , wherein the outer mold is a steel mold.  
   
   
       17 . The device of  claim 16 , wherein the wall thickness of the outer mold is at least 8 mm.  
   
   
       18 . The device of  claim 18 , wherein the outer mold comprises at least two mold parts, wherein the mold parts are connected releasably to one another.