Split sleeve cold expansion

In a puller tool of a type which is used for pulling a mandrel axially through a one-piece prestressing sleeve located within a fastener hole in a workpiece, said mandrel having an small diameter rear portion and forwardly thereof having an increasing diameter portion and an adjacent maximum diameter portion, so that the increasing diameter portion and the adjacent maximum diameter portion of the mandrel can exert expansion forces on the sleeve, to cause the sleeve to be expanded in the radial direction and prestress the workpiece around the hole, and in that manner improve fatigue properties of the workpiece, the improvement comprising:

• a tubular sleeve stop surrounding the mandrel and through which the mandrel is pulled, said sleeve stop having a forward end which makes abutting contact with an end of a sleeve;
• a tubular sleeve holder surrounding said sleeve stop, said sleeve holder including axial fingers separated by axial slots, with forward end portions of the fingers defining a sleeve and mandrel receiving end opening and sleeve engaging jaws radially outwardly bounding said opening;
• a tubular nose portion surrounding said sleeve holder;
• wherein said sleeve holder is movable axially between retracted and extended positions, with the jaws of the sleeve holder opening radially when the sleeve holder is extended and closing radially when the sleeve holder is retracted, and
• wherein in use the mandrel is extended, the sleeve holder is extended to radially open said jaws, a sleeve is positioned on the small diameter portion of the mandrel, the rearward end of the sleeve is positioned against the front end of the sleeve stop, and then the sleeve holder is retracted to close the jaws, bringing them into gripping engagement with the sleeve.

Apparatus for radially expanding a sleeve, comprising:

• a puller tool including an elongated tubular nose portion having an forward end;
• an elongated tubular sleeve holder within said nose portion;
• an elongated tubular sleeve stop within said sleeve holder, said sleeve stop having a forward end;
• an elongated mandrel extending through said sleeve stop and including in order a rear end portion, a small diameter portion, an increasing diameter portion, and a maximum diameter portion;
• said sleeve holder including a plurality of axial fingers separated by slots, said fingers having forward end portions which define a front end opening and sleeve gripping jaws radially outwardly bounding said end opening , said jaws being positioned axially forwardly of the front end of the sleeve stop;
• said sleeve holder being movable axially between a retracted position, wherein said jaws are located at least partially within the nose portion and are radially contracted and an extended position wherein said jaws are positioned axially forwardly of the nose portion and are radially expanded;
• a piston within the puller tool connected to the rear end of said mandrel, said piston being extendable and retractable for extending and retracting the mandrel;
• said mandrel having an extended position in which a part of the small diameter portion of the mandrel and the increasing diameter and maximum diameter portions of the mandrel are positioned endwise forwardly of the tubular nose portion;
• wherein in use the mandrel is extended and a sleeve to be expanded is positioned onto the small diameter portion of the mandrel outwardly of the front end of the sleeve stop;
• and
• wherein said piston is retractable to pull the mandrel through the sleeve while the sleeve holder is retracted and a rear end of the sleeve is against the front end of the sleeve stop.

A puller tool for extending and retracting a mandrel, comprising:

• a housing including a forward portion in which a mandrel is guided for axial movement between retracted and extended positions;
• a first piston-cylinder unit within said housing including a first piston and first front and rear working chambers on opposite sides of the piston, and a mandrel mount connected to the piston, said mandrel mount including a front end portion that is connectable to a rear end portion of a mandrel;
• a passageway leading into the first front working chamber, through which pressure is introduced for retracting the piston and in turn retracting a mandrel connected to the piston;
• said first rear working chamber being defined in part by a radial wall, said radial wall including an axial opening;
• a second piston-cylinder unit positioned substantially rearwardly of said radial wall, and including a second piston and a second front working chamber and a second rear working chamber on opposite sides of the second piston, and a piston rod connected to the second piston and extending forwardly through the front forward working chamber and through the opening in the radial wall, said piston rod including a front end within the rear working chamber of the first piston-cylinder unit;
• wherein fluid pressure can be introduced into the second rear working chamber, against the second piston, to extend the second piston and its piston rod, and move the piston rod into contact with the first piston;
• and
• wherein said second piston has a predetermined stroke length and extension of said second piston will extend the first piston, the mandrel holder and the mandrel a predetermined distance, causing a predetermined length of the mandrel to be extended out from the forward portion of the housing.

A puller tool for pulling a mandrel, comprising:

• an elongated tubular housing including a forward portion having a base portion and a nose portion, said base portion including a piston cavity having a forward end and a rearward end, said forward end including a central opening surrounded by an annular radial end wall;
• said nose portion including a central passageway extending forwardly from said central opening, said central passageway including a forward end;
• a tubular sleeve holder including a piston within said piston cavity and a tubular front portion extending forwardly from the piston through the central passageway, said piston including an annular front surface confronting the forward end wall of the cavity, and a rear surface;
• said tubular front portion of the sleeve holder including a plurality of axial fingers separated by axial slots, said fingers having front end portions which define a front end opening and sleeve gripping jaws radially outwardly bounding said end opening;
• passages for delivering fluid pressure to the rear of the piston while the front of the piston is at low pressure, to extend the sleeve holder, and to deliver fluid to pressure to the front of the piston to retract the sleeve holder;
• wherein the fingers of the sleeve holder diverge apart when the sleeve holder is in its extended position, and
• wherein the nose portion of the puller tool contacts the fingers and forces them radially inwardly, and the jaws radially together when the sleeve holder is retracted.

A puller tool for pulling a mandrel, comprising:

• an elongated tubular housing including a forward portion comprising a body portion and a nose portion, said body portion including a piston cavity having a forward end and a rearward end, said forward end including a central opening surrounded by an annular radial end wall;
• said nose portion including a central passageway extending forwardly from said central opening, said central passageway including a forward end;
• a tubular sleeve holder within said forward portion of said housing, including a piston within said piston cavity and a tubular front portion extending forwardly from the piston through the central passageway, said piston including an annular front surface confronting the forward end wall of the cavity, and a rear surface;
• said tubular front portion of the sleeve a plurality of axial fingers separated by axial slots, said fingers having outer end portions which define an outer end opening and sleeve gripping jaws radially outwardly bounding said outer end opening;
• passages for delivering fluid pressure to the rear of the piston while the front of the piston is at low pressure, to extend the sleeve holder, and to deliver fluid pressure to the front of the piston while the rear of the piston is at low pressure, to retract the sleeve holder;
• wherein the fingers of the sleeve holder diverge apart when the sleeve holder is in its extended position, and
• wherein the nose portion of the puller tool contracts the fingers and forces them radially inwardly, and the jaws radially together, when the sleeve holder is retracted.

A method of cold expanding a hole in a workpiece, comprising:

• providing a cold expansion mandrel which includes a rear end, a small diameter portion axially forwardly of said rear end, an increasing diameter portion axially outwardly of said small diameter portion and a maximum diameter portion axially outwardly of said in creasing diameter portion;
• providing a puller tool which is adapted to extend and retract the cold expansion mandrel, and connecting the rear end of the mandrel to the puller tool;
• providing the puller tool with a tubular sleeve stop in a surrounding relationship to the mandrel, said sleeve stop including a forward end;
• providing the puller tool with a sleeve holder in a surrounding relationship to the sleeve stop, said sleeve holder being extendable and retractable independently of the mandrel and including a forward end portion divided by axial slots into axial fingers, with the front end portions of the fingers defining a sleeve and mandrel receiving end opening and sleeve retaining jaws radially outwardly bounding the end opening;
• providing the puller tool with a tubular nose portion in a surrounding relationship to said sleeve holder, said nose portion being adapted to engage and radially contract the jaws of the sleeve holder in response to a retraction of the sleeve holder;
• extending the sleeve holder axially out from said nose portion to radially expand said jaws;
• extending the mandrel to position a part of the small diameter portion of the mandrel endwise forwardly of the end opening and the sleeve engaging jaws;
• providing a prelubricated cold expansion, one-piece sleeve and positioning such sleeve in a stationary and supported position;
• moving the puller tool to the sleeve to put the mandrel into axial alignment with the sleeve and then moving the puller tool axially to move the mandrel through the sleeve until the sleeve is on the small diameter portion of the mandrel and a rear end of the sleeve is against the front end of the sleeve stop;
• retracting the sleeve holder to contract the jaws sleeve holder into gripping contact with the inner end portion of the sleeve;
• moving the puller tool to a workpiece and aligning the mandrel and sleeve with a hole in the workpiece and moving the puller tool axially to place the mandrel and sleeve into the hole in the workpiece and place outer end surfaces of the jaws of the sleeve holder into contact with the workpiece where it surrounds the hole in the workpiece;
• holding the end surfaces of the jaws against the workpiece while retracting the mandrel to move the mandrel through the sleeve, so that as the mandrel is retracted the increasing and maximum diameter portions of the mandrel will expand the sleeve radially to cold expand the workpiece material surrounding the hole in the workpiece;
• following retraction of the mandrel, moving the puller tool away from the workpiece while maintaining the sleeve holder in a retracted position, so that the jaws of the sleeve holder will hold onto the sleeve and pull it out from the hole in the workpiece as the puller tool is moving away from the workpiece;
• extending the sleeve holder to move the jaws axially outwardly from the nose portion, and expanding the jaws to remove their grip from the sleeve;
• and
• extending the mandrel while the jaws are expanded, to move the mandrel against the sleeve, so that the mandrel will push the sleeve out from the end opening and free of the sleeve holder.

A method of radially expanding a tubular sleeve, comprising:

• providing a mandrel which includes a rear end portion, a small diameter portion axially outwardly of said rear end portion, an in creasing diameter portion axially outwardly of said small diameter and a maximum diameter portion axially outwardly of said in creasing diameter portion;
• providing a puller tool which is adapted to extend and retract the mandrel, and connecting the rear end portion of the mandrel to the puller tool;
• providing the puller tool with a tubular sleeve stop in a surrounding relationship to the mandrel, said sleeve stop including a front end;
• providing the puller tool with a sleeve holder in a surrounding relationship to the sleeve stop, said sleeve holder being extendible and retractable independently of the mandrel and including a front end portion divided by axial slots into axial fingers, with the front end portions of the fingers defining a sleeve and mandrel receiving end opening and sleeve retaining jaws radially outwardly bounding the end opening;
• providing the puller tool with a tubular nose portion in a surrounding relationship to said sleeve holder, said nose portion being adapted to engage and radially contract the jaws of the sleeve holder in response to a retraction of the sleeve holder;
• extending the sleeve holder axially out from said nose portion to radially expand said jaws;
• extending the mandrel to position a part of the small diameter portion of the mandrel endwise outwardly of the end opening and the sleeve engaging jaws;
• providing a sleeve on the small diameter portion of the mandrel, outwardly of the end opening and the sleeve engaging jaws and moving the sleeve relatively along the mandrel until a rear end of the sleeve is against the front end of the sleeve stop;
• retracting the sleeve holder to contract the jaws of the sleeve holder into gripping contact with the inner end portion of the sleeve;
• moving the puller tool to a member which includes an opening and inserting the mandrel and sleeve into such opening;
• and
• retracting the mandrel through the sleeve so that as the mandrel is retracted the increasing and maximum diameter portions of the mandrel will expand the sleeve radially.

Apparatus for delivering cold expansion sleeves to a holding station, into a position to be picked up by a puller gun, each said sleeve having a front end and a rear end, said apparatus comprising:

• a housing defining a longitudinal passageway into which a series of cold expansion sleeves are moved, sideways to the sleeve holding station;
• said passageway including a longitudinal cam surface confronting the front ends of the sleeves;
• said cam surface being configured to contact the front end of each sleeve as the sleeve approaches the holding station, and push such sleeve axially rearwardly;
• and
• said housing including a window through which a rear portion of each sleeve extends when it is at the holding station.