Concentric pneumatic/hydraulic power feed apparatus

A power feed apparatus for feeding an output shaft of a power tool in a linear motion relative to a workpiece without impeding rotational movement of said output shaft, and in a manner which distributes thrust forces imparted to said output shaft evenly concentrically about said output shaft while said output shaft is moved linearly between a retracted position and an extended position, said apparatus comprising:

• a first tubular member including an outer sleeve and an inner tube defining an annular area therebetween, said first tubular member adapted to be fixedly secured to a substructure associated with said workpiece;
• a second tubular member including a second outer tubular sleeve and a second inner tubular sleeve disposed concentrically within said second outer sleeve, said output shaft being supported from said second tubular member and extending concentrically through said second inner tubular sleeve and said inner tube;
• said outer sleeve and said inner tube defining a first annular area therebetween in which a portion of said second inner tubular sleeve travels during movement of said second tubular member;
• and
• a first annular fluid chamber formed between said second inner tubular sleeve and said outer sleeve such that a pressurized fluid admitted into said first fluid chamber causes linear movement of said output shaft from said retracted position to said extended position.

A method for feeding an output shaft of a power tool in a linear motion relative to a workpiece without impeding rotational movement of said output shaft, and in a manner which distributes thrust forces imparted to said output shaft evenly concentrically about said output shaft while said output shaft is moved linearly between a retracted position and an extended position, relative to a workpiece, the method comprising:

• providing a first tubular member which is adapted to be fixedly attached to a substructure associated with said workpiece, and which includes a bore for permitting said output shaft to extend therethrough into said workpiece;
• providing a second tubular member having a diameter sufficiently large to permit sliding movement over said first tubular member, said second tubular member including a portion arranged to extend within an interior area of said first tubular member, said second tubular member supporting a motor thereon for driving said output shaft, and said working element being aligned concentrically with said bore in said first tubular member;
• forming a first annular fluid chamber within said first tubular member for causing said second tubular member to be urged linearly toward said first tubular member when a pressurized fluid is injected into said first annular fluid chamber, thereby causing said output shaft to be extended from said first tubular member toward said workpiece;
• and
• forming a second annular fluid chamber within said second tubular member for causing said second tubular member to be retracted away from said workpiece when a pressurized fluid is injected into said second annular fluid chamber.

A method for feeding a output shaft of a power tool in a linear motion relative to a workpiece without impeding rotational movement of said output shaft, and in a manner which distributes thrust forces imparted to said output shaft evenly concentrically about said output shaft while said output shaft is moved linearly between a retracted position and an extended position relative to a workpiece, the method comprising:

• providing a first tubular member which is adapted to be fixedly attached to a substructure associated with said workpiece, and which includes a bore for permitting said output shaft to extend therethrough into said workpiece;
• providing a second tubular member having a diameter sufficiently large to permit sliding movement over said first tubular member, said second tubular member including a portion arranged to extend within an interior area of said first tubular member, said second tubular member supporting a motor thereon for driving said output shaft, and said output shaft being aligned concentrically with said bore in said first tubular member;
• forming a first annular fluid chamber within said first tubular member for causing said second tubular member to be urged linearly toward said first tubular member when a pressurized fluid is injected into said first annular fluid chamber, thereby causing said output shaft to be extended from said first tubular member toward said workpiece;
• and
• using a biasing element disposed within one of said first and second tubular members to retract said output shaft.