Apparatus (101) for supporting a workpiece (201), comprising a frame structure (102) for holding a workpiece (201), a base element (103) for supporting the frame structure (102), and a tool support element (110) for holding a tool. The frame structure (102) comprises lower and upper frame elements (107, 108) between which a workpiece (201) is receivable, and the upper frame element (108) is movable with respect to the lower frame element (107) in a Z-axis direction (106), for clamping a workpiece (102) therebetween. The tool support element (110) is movable with respect to the upper frame element (108) in an X-axis direction (104). The frame structure (102) is movable with respect to the base element (103), and with respect to a workpiece held between the lower and upper frame elements (107, 108), in a Y-axis direction (105). A CNC machine comprising the apparatus (101).

Method for controlling a sheet feeding device (1) comprising an elevator (2) for a stack of sheets, and an air supply system (3) configured to supply and direct one of more air streams towards an upper region (4) of the sheet feeding device for floating a plurality of upper sheets of the stack of sheets, wherein the elevator comprises a vertically movable support (5) for supporting the stack of sheets from below, wherein the sheet feeding device comprises an optical sensor (6) positioned adjacent the floated sheets for measuring light reflected from the floated sheets at a plurality of different heights, wherein the method comprises the steps of: continuously deriving from the optical sensor a density reading (DR) indicating the density of sheets floated, continuously deriving an average density (AD) based on a plurality of density readings, continuously deriving an upper density limit (UDL) based on the average density multiplied by a predetermined upper density limit factor (UDLF), continuously deriving a lower density limit (LDL) based on the average density multiplied by a predetermined lower density limit factor (LDLF), adjusting a first operating parameter (OP) of the sheet feeding device should the density reading exceed the upper density limit, wherein the adjustment of the first operating parameter is such as to decrease the density of floated sheets, and adjusting the first operating parameter of the sheet feeding device should the density reading subceed the lower density limit, wherein the adjustment of the first operating parameter is such as to increase the density of floated sheets. Also, a sheet feeding device connected to a controller configured to operate according to this method.

Method for controlling a sheet feeding device (1) comprising an elevator (2) for a stack of sheets, and an air supply system (3) configured to supply and direct one of more air streams towards an upper region (4) of the sheet feeding device for floating a plurality of upper sheets of the stack of sheets, wherein the elevator comprises a vertically movable support (5) for supporting the stack of sheets from below, wherein the sheet feeding device comprises an optical sensor (6) positioned adjacent the floated sheets for measuring light reflected from the floated sheets at a plurality of different heights, wherein the method comprises the steps of: continuously deriving from the optical sensor a density reading (DR) indicating the density of sheets floated, continuously deriving an average density (AD) based on a plurality of density readings, continuously deriving an upper density limit (UDL) based on the average density multiplied by a predetermined upper density limit factor (UDLF), continuously deriving a lower density limit (LDL) based on the average density multiplied by a predetermined lower density limit factor (LDLF), adjusting a first operating parameter (OP) of the sheet feeding device should the density reading exceed the upper density limit, wherein the adjustment of the first operating parameter is such as to decrease the density of floated sheets, and adjusting the first operating parameter of the sheet feeding device should the density reading subceed the lower density limit, wherein the adjustment of the first operating parameter is such as to increase the density of floated sheets. Also, a sheet feeding device connected to a controller configured to operate according to this method.

Method for controlling a sheet feeding device (1) comprising an elevator (2) for a stack of sheets, and an air supply system (3) configured to supply and direct one of more air streams towards an upper region (4) of the sheet feeding device for floating a plurality of upper sheets of the stack of sheets, wherein the elevator comprises a vertically movable support (5) for supporting the stack of sheets from below, wherein the sheet feeding device comprises an optical sensor (6) positioned adjacent the floated sheets pot for measuring light reflected from the floated sheets at a plurality of different heights, wherein the method comprises the steps of: continuously deriving from the optical sensor a density reading (DR) indicating the density of sheets floated, continuously deriving an average density (AD) based on a plurality of density readings, continuously deriving an upper density limit (UDL) based on the average density multiplied by a predetermined upper density limit factor (UDLF), continuously deriving a lower density limit (LDL) based on the average density multiplied by a predetermined lower density limit factor (LDLF), adjusting a first operating parameter (OP) of the sheet feeding device should the density reading exceed the upper density limit, wherein the adjustment of the first operating parameter is such as to decrease the density of floated sheets, and adjusting the first operating parameter of the sheet feeding device should the density reading subceed the lower density limit, wherein the adjustment of the first operating parameter is such as to increase the density of floated sheets. Also, a sheet feeding device connected to a controller configured to operate according to this method.

Method for controlling a sheet feeding device (1) comprising an elevator (2) for a stack of sheets, and an air supply system (3) configured to supply and direct one of more air streams towards an upper region (4) of the sheet feeding device for floating a plurality of upper sheets of the stack of sheets, wherein the elevator comprises a vertically movable support (5) for supporting the stack of sheets from below, wherein the sheet feeding device comprises an optical sensor (6) positioned adjacent the floated sheets pot for measuring light reflected from the floated sheets at a plurality of different heights, wherein the method comprises the steps of: continuously deriving from the optical sensor a density reading (DR) indicating the density of sheets floated, continuously deriving an average density (AD) based on a plurality of density readings, continuously deriving an upper density limit (UDL) based on the average density multiplied by a predetermined upper density limit factor (UDLF), continuously deriving a lower density limit (LDL) based on the average density multiplied by a predetermined lower density limit factor (LDLF), adjusting a first operating parameter (OP) of the sheet feeding device should the density reading exceed the upper density limit, wherein the adjustment of the first operating parameter is such as to decrease the density of floated sheets, and adjusting the first operating parameter of the sheet feeding device should the density reading subceed the lower density limit, wherein the adjustment of the first operating parameter is such as to increase the density of floated sheets. Also, a sheet feeding device connected to a controller configured to operate according to this method.

Apparatus (101) for supporting a workpiece (201), comprising a frame structure (102) for holding a workpiece (201), a base element (103) for supporting the frame structure (102), and a tool support element (110) for holding a tool. The frame structure (102) comprises lower and upper frame elements (107, 108) between which a workpiece (201) is receivable, and the upper frame element (108) is movable with respect to the lower frame element (107) in a Z-axis direction (106), for clamping a workpiece (102) therebetween. The tool support element (110) is movable with respect to the upper frame element (108) in an X-axis direction (104). The frame structure (102) is movable with respect to the base element (103), and with respect to a workpiece held between the lower and upper frame elements (107, 108), in a Y-axis direction (105). A CNC machine comprising the apparatus (101).

A sheet feeding apparatus includes: a front edge air part that blows front edge air, along a conveying direction of a sheet stacked, to a front edge side of the sheet; side edge air parts that are provided to face each other along an orthogonal direction to the conveying direction of the sheet and blow side edge air, along the orthogonal direction, to respective side edge sides of the sheet; a suction part that suctions, by a negative pressure, the sheet to which the front edge air and the side edge air are blown; and a conveyer that suctions and conveys the sheet suctioned by the suction part, wherein the front edge air and the side edge air are blown to the sheet to float the sheet in a posture in which a portion protruding from the conveyer of the sheet is lower than a conveying surface of the conveyer.

A sheet feeding apparatus includes: a front edge air part that blows front edge air, along a conveying direction of a sheet stacked, to a front edge side of the sheet; side edge air parts that are provided to face each other along an orthogonal direction to the conveying direction of the sheet and blow side edge air, along the orthogonal direction, to respective side edge sides of the sheet; a suction part that suctions, by a negative pressure, the sheet to which the front edge air and the side edge air are blown; and a conveyer that suctions and conveys the sheet suctioned by the suction part, wherein the front edge air and the side edge air are blown to the sheet to float the sheet in a posture in which a portion protruding from the conveyer of the sheet is lower than a conveying surface of the conveyer.