Method and device for producing a foamable, strip-like pressed powder metal sheet blank by means of cold rolling, and pressed powder metal sheet blank

Abstract

A method and a device for producing a foamable, strip-like pressed powder metal sheet blank, and to such a pressed powder metal sheet blank. Foamable pressed powder metal sheet blanks are commonly produced by means of hot pressing. However, this costs energy and can adversely affect the quality of the metal foam produced from the pressed powder metal sheet blank due to the gasification of the foaming agent. Therefore, the pressed powder metal sheet blank is produced from a powder mixture containing at least one metal powder and a foaming agent powder by means of cold rolling. In this way, a wider range of foaming agents can be used and the amount of energy required to produce the pressed powder metal sheet blank is reduced.

1 . A method for producing a foamable, strip-like pressed powder metal sheet blank ( 2 ) from a powder mixture ( 4 ) containing at least one metal powder ( 8 ) and a foaming agent powder ( 10 ), wherein the metal powder ( 8 ) contains a metal from the group comprising aluminum, copper, zinc, lead and iron, wherein the foaming agent powder ( 10 ) contains a foaming agent for foaming the pressed powder metal sheet blank, and wherein the powder mixture ( 4 ) is cold-rolled between two rotating rollers ( 18 ) to form the pressed powder metal sheet blank ( 2 ). 
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . The method according to  claim 1 , wherein the powder mixture ( 4 ) is conveyed exclusively by gravity ( 20 ) and the rotating rollers ( 18 ) between the rotating rollers ( 18 ). 
     
     
         5 . The method according to  claim 1 , wherein a level ( 24 ) of the powder mixture ( 4 ) above the rollers ( 18 ) is automatically kept constant. 
     
     
         6 . The method according to  claim 1 , wherein the metal powder ( 4 ) is heat-treated before being brought together with the foaming agent powder ( 10 ). 
     
     
         7 . The method according to  claim 1 , wherein the powder mixture ( 4 ) is cold-rolled at room temperature. 
     
     
         8 . The method according to  claim 1 , wherein the pressed powder metal sheet blank ( 2 ) is cooled after leaving a gap ( 22 ) between the rollers ( 18 ). 
     
     
         9 . The method according to  claim 1 , wherein the pressed powder metal sheet blank ( 2 ) is moved through a heat insulated area ( 57 ) immediately downstream of the rollers ( 18 ). 
     
     
         10 . The method according to  claim 1 , wherein heat dissipation from the pressed powder metal sheet blank ( 2 ) after leaving the rollers ( 18 ) is greater in a center area ( 59 ) located centrally between edges ( 60 ) than at the edges ( 60 ). 
     
     
         11 . The method according to  claim 1 , wherein a rolling direction ( 56 ) coincides with the direction of gravity ( 20 ). 
     
     
         12 . The method according to  claim 1 , wherein the rollers exert a contact pressure of at least 200 MPa and/or at most 500 MPa. 
     
     
         13 . The method according to  claim 1 , wherein above the rollers ( 18 ) there is at most 400 mm of powder mixture ( 4 ). 
     
     
         14 . The method according to  claim 1 , wherein a feed angle ( 64 ) measured from a center ( 68 ) of a roller ( 18 ), via which the powder mixture ( 4 ) is in contact with a surface ( 66 ) of the roller ( 18 ), is at most 350 and/or at least 15°. 
     
     
         15 . The method according to  claim 1 , wherein the metal powder ( 8 ) comprises a wrought aluminum alloy and/or a cast aluminum alloy, or consists of a wrought aluminum alloy and/or a cast aluminum alloy. 
     
     
         16 . The method according to  claim 1 , wherein the foaming agent powder comprises titanium hydride. 
     
     
         17 . The method according to  claim 1 , wherein at least one of the rollers ( 18 ) is cooled during the cold rolling. 
     
     
         18 . The method according to  claim 17 , wherein a surface ( 66 ) of the at least one roller ( 18 ) is cooled by a cooling air flow ( 55 ). 
     
     
         19 . The method according to  claim 18 , wherein the cooling air flow ( 55 ) is sucked off. 
     
     
         20 . A foamable pressed powder metal sheet blank produced by the method according to  claim 1 . 
     
     
         21 . A method of using a cold rolling machine ( 51 ) with two rotating rollers ( 18 ) for producing a foamable pressed powder metal sheet blank ( 2 ) from a powder mixture ( 4 ) containing a metal powder ( 8 ) and a foaming agent powder ( 10 ) by means of cold rolling ( 6 ), wherein the metal powder contains a metal from the group comprising aluminum, copper, zinc, lead and iron and wherein the foaming agent powder contains a foaming agent for foaming the pressed powder metal sheet blank ( 2 ) or consists of a foaming agent for foaming the pressed powder metal sheet blank ( 2 ). 
     
     
         22 . A device ( 1 ) for carrying out the method according to  claim 1 .