Abrading tool clip with automatic take-up

Claim 1

An automatic take-up clip for holding a sheet of abrading material on an abrading tool, comprising: a first structure having a backing surface adjacent which an end portion of said abrading sheet is to be received; a clamping element made of sheet form spring material and having a clamping portion adapted to be received opposite said backing surface and to clamp the abrading sheet thereagainst; a link structure for movably mounting said clamping element; first pivotal connection means attaching said link structure to said first structure for swinging movement relative thereto about a first axis located behind said backing surface; second pivotal connection means attaching said clamping element to said link structure for relative pivotal movement about a second axis which upon pivotal movement of said link structure about said first axis swings between a released position freeing said abrading sheet from clamped retention by said element and an active clamping position in which said second axis is behind said first axis and slightly overcenter with respect to said first axis and said clamping portion of said element, and in which active position said clamping portion is yieldingly urged tightly against said abrading sheet by the reslience of the clamping element; said backing surface having a camming portion which, at each of a series of different locations along a predetermined path of take-up movement, is disposed at a slight camming angle of not more than about 20° with respect to a plane perpendicular to a straight line extending between said active position of said second axis and the part of said camming portion of the backing surface which is nearest to said active position of the second axis, so that as said camming portion advances in a predetermined abrading sheet take-up direction it also advances slightly closer to said active position of the second axis; said clamping portion of said clamping element being adapted, upon initial actuation of the clamping element to active position, to be received opposite, and clamp said sheet against, a part of said camming portion of the backing surface which is relatively far from said second axis, and to then be cammed with the sheet, by the yielding force of said clamping element, along said camming portion of the surface in said take-up direction and to positions opposite regions of said camming portion which are progressively closer to the second axis, to thereby automatically take up slack in the sheet; said clamping portion being constructed to grip the sheet in a manner tending to cause the sheet by such gripped engagement to hold said clamping portion of the clamping element against movement in take-up direction except in conjunction with corresponding movement of the sheet to thereby attain said automatic take-up action.