Sand core, coating apparatus and method for producing a sand core, in each case for the production of ventilated brake discs

Abstract

A method for producing a sand core for the production of ventilated brake discs provides a sand body which has a circular and disc-shaped basic form and which has apertures. The apertures are arranged in circumferentially distributed fashion in the region of a ring of the circular and disc-shaped basic form. Subsequently, the sand body is partially coated with a liquid facing material, wherein the sand body is, in the region of a coating ring, washed around with the liquid facing material by way of a flooding process, wherein the coating ring covers the ring with the apertures, and wherein the apertures serve as flow ducts for the liquid facing material. Subsequently, the liquid facing material adhering to the sand body is dried. Also disclosed is a sand core and a coating apparatus for carrying out the partial coating of a sand body.

1 . Method for producing a sand core ( 1 ) for the production of ventilated brake discs ( 100 ), comprising the steps:
 providing a sand body ( 10 ) which has a circular and disc-shaped basic form ( 11 ) and which has apertures ( 12 ), wherein the apertures ( 12 ) are arranged in circumferentially distributed fashion in the region of a ring ( 13 ) of the circular and disc-shaped basic form ( 11 );   partially coating the sand body ( 10 ) with a liquid facing material ( 30 ), wherein the sand body ( 10 ) is, in the region of a coating ring ( 31 ), washed around with the liquid facing material ( 30 ) by way of a flooding process, wherein the coating ring ( 31 ) covers the ring ( 13 ) with the apertures ( 12 ), and wherein the apertures ( 12 ) serve as flow ducts for the liquid facing material ( 30 );   drying the liquid facing material ( 30 ) adhering to the sand body ( 10 ).   
     
     
         2 . Method according to  claim 1 , characterized in that, owing to targeted guidance of the liquid facing material ( 30 ), a core mark ( 14 ) which surrounds the ring ( 13 ) with the apertures ( 12 ) is not washed around during the partial coating of the sand body ( 10 ). 
     
     
         3 . Method according to  claim 1 , characterized in that, owing to targeted guidance of the liquid facing material ( 30 ), a centre region ( 15 ) which is situated within the ring ( 13 ) with the apertures ( 12 ) is not washed around during the partial coating of the sand body ( 10 ). 
     
     
         4 . Method according to  claim 1 , characterized in that the apertures ( 12 ) are of slot-shaped form and are closed at the end sides, and each extend from the inside outward with respect to the circular and disc-shaped basic form ( 11 ). 
     
     
         5 . Method according to  claim 1 , characterized in that the sand body ( 10 ) is oriented horizontally during the partial coating with facing material ( 30 ), and a liquid flow of the facing material ( 30 ) falls onto the sand body ( 10 ) from above. 
     
     
         6 . Method according to  claim 1 , characterized in that the sand body ( 10 ) is oriented horizontally during the partial coating with facing material ( 30 ), and a liquid flow of the facing material ( 30 ) impinges on the sand body ( 10 ) from below. 
     
     
         7 . Method according to  claim 4 , characterized in that the liquid flow of the facing material ( 30 ) is dispensed from an outlet apparatus ( 205 ,  210 ) which has individual holes ( 206 ,  211 ) distributed over an area. 
     
     
         8 . Method according to  claim 1 , characterized in that a liquid circuit is formed during the flooding process, wherein the liquid facing material ( 30 ) not adhering to the sand body ( 10 ) is collected downstream of the sand body ( 10 ) as viewed in the flow direction. 
     
     
         9 . Method according to  claim 1 , characterized in that the liquid facing material ( 30 ) flows to the sand body ( 10 ) from an elevated tank ( 203 ). 
     
     
         10 . Method according to  claim 1 , characterized in that at least 95% of the liquid facing material ( 30 ) not adhering to the sand body ( 10 ) flows through the apertures ( 12 ) during the flooding process. 
     
     
         11 . Method according to  claim 1 , characterized in that the sand body ( 10 ) is rotated horizontally while being washed around with liquid facing material ( 30 ). 
     
     
         12 . Method according to  claim 1 , characterized in that the sand body ( 10 ) is rotated and/or pivoted during the drying of the liquid facing material ( 30 ). 
     
     
         13 . Method according to  claim 1 , characterized in that the sand body ( 10 ) is, during the partial coating, mounted by way of a workpiece mount ( 201 ), which workpiece mount moves the sand body ( 10 ) into a vertically falling liquid flow of liquid facing material ( 30 ), subsequently rotates the sand body in the liquid flow for a defined time period, and, after the flooding process, rotates and/or pivots the sand body ( 10 ) for the purposes of drying the liquid facing material ( 30 ). 
     
     
         14 . Method according to  claim 1 , characterized in that the sand body ( 10 ) has a ring-shaped first bevel ( 16 ), wherein the first bevel ( 16 ) is formed on the top side (S 1 ) and/or on the bottom side (S 2 ) of the circular and disc-shaped basic form ( 11 ), and wherein the first bevel ( 16 ) radially surrounds the ring ( 13 ) with the apertures ( 12 ). 
     
     
         15 . Method according to  claim 1 , characterized in that the sand body ( 10 ) has a ring-shaped second bevel ( 17 ), wherein the second bevel ( 17 ) is formed on the top side (S 1 ) and/or on the bottom side (S 2 ) of the circular and disc-shaped basic form ( 11 ), and wherein the ring ( 13 ) with the apertures ( 12 ) radially surrounds the second bevel ( 17 ). 
     
     
         16 . Method according to  claim 1 , characterized in that the sand body ( 10 ) has feet ( 18 ) on the outer circumference of the circular and disc-shaped basic form ( 11 ). 
     
     
         17 . Sand core ( 1 ) for the production of ventilated brake discs ( 100 ), having a sand body ( 10 ) with a circular and disc-shaped basic form ( 11 ) and with apertures ( 12 ), wherein the apertures ( 12 ) are arranged in circumferentially distributed fashion in the region of a ring ( 13 ) of the circular and disc-shaped basic form ( 11 ), and wherein the sand body ( 10 ) has a core mark ( 14 ) which surrounds the ring ( 13 ) with the apertures ( 12 ), characterized in that a coating is applied in the region of a coating ring ( 31 ) of the sand body ( 10 ), wherein the coating is composed of a dried facing material ( 30 ), wherein the coating ring ( 31 ) covers the ring ( 13 ) with the apertures ( 12 ), and wherein at least 50% of the surface of the core mark ( 14 ) of the sand body ( 10 ) is free from the coating. 
     
     
         18 . Coating apparatus ( 200 ) for carrying out the partial coating of a sand body ( 10 ) as per a method according to  claim 1 , having:
 a workpiece mount ( 201 ) with a holding means ( 202 ) for holding the sand body ( 10 ), a holding arm ( 209 ) for moving the sand body ( 10 ) in space, and a rotary drive for rotating the sand body ( 10 );   an elevated tank ( 203 ) for storing liquid facing material ( 30 );   an outlet apparatus ( 205 ,  210 ) which is arranged below the elevated tank ( 203 ) and is connected in terms of flow to the latter;   a collecting tank ( 204 ) below the outlet apparatus ( 205 ,  210 ); and   a return delivery line ( 207 ) with pump ( 208 ) between the collecting tank ( 204 ) and the elevated tank ( 203 ).