Method and tool head for machining optically active surfaces, particularly surfaces of progressive spectacle lenses, which are symmetrical in pairs

Abstract

A method and a tool head are provided for the chip-removingly machining of pairwise symmetrical, optically effective surfaces, in particular of surfaces of progressive power spectacle lenses. The spectacle lenses are rotated about a first axis and are displaced along the axis. Further, a chip-removing tool is provided being positioned and being adapted to be fed-in, such that a cutting edge of the tool is guided over the surface along a spiralled path and along an elevation function given by the shape of the spectacle lens, when the latter is rotated about the first axis. For machining right side spectacle lenses and left side spectacle lenses, the right side spectacle lenses are rotated about the first axis in a first rotational direction, and the left side spectacle lenses are rotated about the first axis in a second rotational direction opposite the first rotational direction. The tool head comprises chucking means defining an axis of the tool head, and a tool carrier section having at least two lathing tools arranged at a periphery thereof. The one lathing tool of the pair is oriented in the one circumferential direction of the periphery, and the other lathing tool of the pair is oriented in the opposite circumferential direction of the periphery. At least one, preferably all of the lathing tools are provided with adjustment means allowing an adjustment of a point of engagement of the lathing cutting edge.

1 . A method for machining pairwise symmetrical, optically effective surfaces by chip-removing, wherein said surfaces are rotated about a first axis and are displaced along said axis, a chip-removing tool being provided, said tool being positioned and being adapted to be fed in, such that a cutting edge of said tool is guided over said surface along a spiralled path and along an elevation function given by said shape of said spectacle lens, when said spectacle lens is rotated about said first axis, wherein for machining right side spectacle lenses and left side spectacle lenses, said right side spectacle lenses are rotated about said first axis in a first rotational direction, and said left side spectacle lenses are rotated about said first axis in a second rotational direction opposite said first rotational direction.  
   
   
       2 . The method of  claim 1 , wherein said optically effective surfaces are surfaces of progressive power spectacle lenses.  
   
   
       3 . The method of  claim 2 , wherein for machining right side spectacle lenses and left side spectacle lenses of same optical power, said spectacle lenses are displaced along said first axis in a same manner.  
   
   
       4 . The method of  claim 2 , wherein said chip-removing is executed by lathing.  
   
   
       5 . The method of  claim 4 , wherein prior to said lathing said spectacle lenses are pre-machined by milling.  
   
   
       6 . The method of claims  4 , wherein a first lathing tool is used during said lathing of said right side spectacle lens and a second lathing tool is used during said lathing of said left side spectacle lens, said lathing tools being oppositely oriented with respect to said direction of said spiralled path.  
   
   
       7 . The method of  claim 6 , wherein said lathing tools have a lathing cutting edge and are adjusted with respect to a position of said lathing cutting edge.  
   
   
       8 . A tool head for machining pairwise symmetrical, optically effective surfaces by chip-removing, comprising chucking means defining an axis of said tool head, and a tool carrier section having at least two lathing tools arranged at a periphery thereof, said lathing tools being each provided with a lathing cutting edge, wherein at least one of said lathing tools is provided with adjustment means allowing an adjustment of a point of engagement of said lathing cutting edge with said surface.  
   
   
       9 . The tool head of  claim 8 , being adapted to machine surfaces of progressive power spectacle lenses.  
   
   
       10 . The tool head of  claim 8 , wherein preferably all of said lathing tools are provided with said adjustment means.  
   
   
       11 . The tool head of  claim 8 , wherein said adjustment means allow an adjustment of said point of engagement in a direction to said axis.  
   
   
       12 . The tool head of  claim 8 , wherein said adjustment means allow an adjustment of said point of engagement in a direction perpendicular to said axis.  
   
   
       13 . The tool head of  claim 8 , wherein, further, milling tools are arranged at said periphery of said tool carrier section.  
   
   
       14 . The tool head of  claim 9 , wherein said milling tools have milling cutting edges with a point of engagement with said surface located on a cutting circle extending about said axis, said points of engagement of said lathing cutting edges being located within said cutting circle at a predetermined distance thereto.  
   
   
       15 . A tool head for machining pairwise symmetrical, optically effective surfaces by chip-removing, comprising chucking means defining an axis of said tool head, and a tool carrier section having at least two lathing tools arranged at a periphery thereof, wherein at least one pair of lathing tools is provided, one lathing tool of said pair being oriented in one circumferential direction of said periphery, and another lathing tool of said pair being oriented in an opposite circumferential direction of said periphery.  
   
   
       16 . The tool head of  claim 15  being adapted to machine surfaces of progressive power spectacle lenses.  
   
   
       17 . The tool head of  claim 15 , wherein two pairs of lathing tools are provided.  
   
   
       18 . The tool head of  claim 15 , wherein, further, milling tools are arranged at said periphery of said tool carrier section.  
   
   
       19 . The tool head of  claim 18 , wherein said milling tools have milling cutting edges with a point of engagement with said surface located on a cutting circle extending about said axis, said points of engagement of said lathing cutting edges being located within said cutting circle at a predetermined distance thereto.