Method for automated installation of semi-tubular fastener rivets

A method for automated installation of a semi-tubular fastener rivet, the method comprising:

• controlling, using a controller, a numerical control drilling and riveting machine having an upper head and a lower head, to control movement of a lower pressure bushing on the lower head, to apply a clamping force to hold a composite workpiece against an upper pressure bushing on the upper head;
• controlling, using the controller, an upper drill spindle on the upper head, to drill a rivet-receiving hole from an upper side of the composite workpiece and to countersink the rivet-receiving hole, to obtain an upper countersink of the rivet-receiving hole;
• controlling, using the controller, a lower drill spindle on the lower head, to countersink the rivet-receiving hole from a lower side of the composite workpiece, to obtain a lower countersink of the rivet-receiving hole;
• controlling, using the controller, movement of an upper anvil on the upper head from a retracted position to an installation position, in which the upper anvil is aligned to insert the semi-tubular fastener rivet in the rivet-receiving hole;
• obtaining a measurement of a distance between the upper pressure bushing and the lower pressure bushing, representing a workpiece thickness, and determining, via the controller, the workpiece thickness within which a zone constraint is defined by the controller for limiting travel of the lower anvil, to avoid collision with the composite workpiece;
• and
• controlling, using the controller, movement of a lower anvil, to apply an upset force to a tail portion of the semi-tubular fastener rivet installed in the rivet-receiving hole, the controller monitoring a load cell for providing a signal indicative of a level of the upset force applied by the lower anvil,
• wherein the controller is configured to control movement of the lower anvil to apply the upset force to the tail portion of the semi-tubular fastener rivet installed in the rivet-receiving hole, without exceeding a predetermined upset force, and
• wherein the controller is configured to direct movement of a nose of the lower anvil within the lower countersink of the rivet-receiving hole to a nominal distance beyond a lower surface plane of a lower surface on the lower side of the composite workpiece, such that the nose of the lower anvil applies the upset force to the tail portion of the semi-tubular fastener rivet and forms a predetermined flare contour in the tail portion within the lower countersink, and such that the predetermined flare contour is beneath the lower surface of the composite workpiece, and wherein the controller is configured to direct movement beyond the zone constraint of the nose of the lower anvil into the lower countersink of the rivet-receiving hole, to apply the upset force to the tail portion of the semi-tubular fastener rivet, such that the lower anvil causes flaring of the tail portion within the lower countersink of the rivet-receiving hole.

A method for automated installation of a semi-tubular fastener rivet, the method comprising:

• positioning a composite workpiece in a numerical control drilling and riveting machine, the numerical control drilling and riveting machine having an upper head with an upper pressure bushing, an upper drill spindle, and an upper anvil, and the numerical control drilling and riveting machine having a lower head with a lower pressure bushing, a lower drill spindle, and a lower anvil, and the numerical control drilling and riveting machine coupled to a control system controlled with a controller, to control movement of the lower pressure bushing on the lower head;
• clamping the composite workpiece against the upper pressure bushing, using the lower pressure bushing, to apply a clamping force to hold the composite workpiece against the upper pressure bushing on the upper head;
• drilling and countersinking, with the upper drill spindle, a rivet-receiving hole in an upper side of the composite workpiece, to obtain an upper countersink of the rivet-receiving hole;
• countersinking, with the lower drill spindle, the rivet-receiving hole from a lower side of the composite workpiece, to obtain a lower countersink of the rivet-receiving hole;
• moving the upper anvil from a retracted position to an installation position, in which the upper anvil is aligned to insert the semi-tubular fastener rivet in the rivet-receiving hole;
• obtaining a measurement of a distance between the upper pressure bushing and the lower pressure bushing, representing a workpiece thickness, and determining the workpiece thickness within which a zone constraint is defined by the controller for limiting travel of the lower anvil, to avoid collision with the composite workpiece;
• and
• moving the lower anvil, to apply an upset force to a tail portion of the semi-tubular fastener rivet installed in the rivet-receiving hole, without exceeding a predetermined upset force, and monitoring a load cell coupled to the lower anvil for providing a signal indicative of a level of the upset force applied by the lower anvil,
• wherein a nose of the lower anvil is moved within the lower countersink of the rivet-receiving hole to a nominal distance beyond a lower surface plane of a lower surface on the lower side of the composite workpiece, such that the nose of the lower anvil applies the upset force to the tail portion of the semi-tubular fastener rivet and forms a predetermined flare contour in the tail portion within the lower countersink, and such that the predetermined flare contour is beneath the lower surface of the composite workpiece, and wherein the controller is configured to direct movement beyond the zone constraint of the nose of the lower anvil into the lower countersink of the rivet-receiving hole, to apply the upset force to the tail portion of the semi-tubular fastener rivet, such that the lower anvil causes flaring of the tail portion within the lower countersink of the rivet-receiving hole.