Apparatus for adjusting the lip opening of an extrusion die

Abstract

Method of adjusting the lip opening of an extrusion die for stratiform material, with the characteristic that it consists in the combination of, on the one side, the control of the heating of bar shaped elements ( 9 ) which act upon at least one of the lips ( 6-7 ) of the lip opening ( 5 ), in function of the thickness of the formed material, and on the other hand, the common cooling of several bar shaped elements ( 9 ) by forcing a cooling medium along these elements ( 9 ).

I claim:  
     
       1. An apparatus for adjustment of a lip opening of an extrusion die, comprising: 
       at least two lip elements each having a longitudinal axis, said two lip elements  defining a lip opening therebetween, said lip opening having a width, 
       a plurality of control units positioned at an angle to said longitudinal axes  width of said lip elements  opening, each of said control units including 
       a bar shaped element, 
       a heat expanding arrangement including a heating element for said bar shaped element for increasing  decreasing a thickness of said lip opening by means of thermal expansion of said  
       bar shaped element of a said control units connectedupon heating to engage one of said lip elements,  
       a contracting arrangement comprising a pair of opposing cooling blocks fastened against each other enclosing said bar shaped elements of said plurality of control units  for decreasing of  increasing the thickness of said lip opening by means of cooling of  said plurality of control units by forcing a cooling medium to flow in at least one cooling channel of a said cooling block transversely to said plurality of control units.  
     
     
       2. An apparatus according to  claim 1  wherein each said control unit is a bar shaped element movably attached to one of said lip elements. 
     
     
       3. An apparatus according to claim  2   1 wherein said bar shaped element is attached toengages an outside free end of said one lip element. 
     
     
       4. An apparatus according to claim  2   1 wherein at least one heating element of said heat expanding arrangement  is attached along each of the bar shaped elements and controlled by the individual  corresponding control unit and at least one cooling channel of said contracting arrangement extends transversely to said bar shaped elements . 
     
     
       5. An apparatus according to  claim 4  wherein said contracting arrangement comprises  at least one cooling block having  has at least one recess adapted to accommodate said bar shaped element, at least one opening positioned transversely to said recess is positioned within said cooling block, said opening receiving a said cooling channel. 
     
     
       6. An apparatus according to claim  4   5 wherein a plurality of said recesses and openings are situated within said at least one cooling block. 
     
     
       7. An apparatus according to  claim 6  wherein said two cooling blocks are employed by said contracting arrangement, said cooling blocks are fastened against each other enclosing said bar shaped elements. 
     
     
       8. An apparatus according to claim  7   1 wherein said cooling medium in the  cooling channels of said two cooling blocks flows in the same direction. 
     
     
       9. An apparatus according to claim  8   1 wherein said cooling medium in the  cooling channels of one of said cooling block flows in the direction opposite to the direction of the flow of said cooling medium in the  cooling channels of the other block. 
     
     
       10. An apparatus according to  claim 9  wherein said cooling channels exists  in at least one internal and one external cooling block. 
     
     
       11. An apparatus according to  claim 9  wherein a plurality of cooling channels are situated outside a die block along the bar shaped elements. 
     
     
       12. An apparatus according to claim  7   1 wherein means providing a supply of the flow of the cooling medium consists of at least one collector to which the inlets of the cooling channels are connected and at least one collector to which the outlets of the cooling channels are connected, whereby the cooling medium is fed in the first collector. 
     
     
       13. An apparatus according to claim  9   11 wherein the direction of flow of the cooling medium in the  cooling channels, positioned along an outside portion of the die block along the bar shaped element, is opposite to the direction of the flow in the  cooling channels applied between the die block and the bar shaped elements. 
     
     
       14. An apparatus according to claim  7   1 wherein all cooling channels are situated within at least one cooling block having a plurality of transverse bore holes receiving said bar shaped elements. 
     
     
       15. An apparatus according to claim  7   1 wherein the cooling channels are provided with cooling fins covered by means of a sheet, whereby a forced air stream is guided along the fins. 
     
     
       16. An apparatus according to claim  7   1 wherein the cooling channels are formed by cooling fins on the cooling blocks and which are covered by means of sheets. 
     
     
       17. An apparatus according to claim  7   1 wherein at least between the cooling blocks and a die block an insulating layer is provided. 
     
     
       18. An apparatus according to claim  7   1 wherein the bar shaped element cooperates at one end with a support and at another end cooperatsecooperates with thesaid one lip element. 
     
     
       19. An apparatus according to  claim 14  wherein at least one said lip element consists of a flexible elastic lip adapted to receive a pressure from one end of said bar shaped element while the other end of said bar shaped element pushes against fasteners positioned within the support. 
     
     
       20. An apparatus according to claim  19   11 where in the die block concentric recesses are made around the bar shaped elements. 
     
     
       21. An apparatus according to claim  7   1 wherein the heating elements are put internally in the bar shaped elements. 
     
     
       22. An apparatus according to  claim 21  wherein the heating elements consist of electric heating elements. 
     
     
       23. An apparatus according to  claim 22  wherein each control unit means  is provided to control an electric power supply to the heating elements and thus the bar shaped elements. 
     
     
       24. An apparatus according to  claim 23  wherein the means to control the supply of the electric energy consists of a voltage level control. 
     
     
       25. An apparatus according to  claim 24  wherein the means to control the supply of the electric energy consist of an adjustable pulse generator. 
     
     
       26. An apparatus according to  claim 24  wherein the means to control the supply of the electric energy consist of a frequency generator. 
     
     
       27. An apparatus according to claim  7   1 wherein the control of the heating elements is performed automatically by means of a measuring device controlling the local thickness across the complete width of a fabricated layer.