Rivet Heading Machine

Overview

A rivet heading machine forms the head of a rivet by upsetting wire cold, the same basic process used for bolts but tuned for the short, simple shape of a rivet. The machine cuts a blank from wire to the rivet length, grips its shank in a die, and strikes the protruding end with a punch so the metal swells into a round, pan, flat, or countersunk head. The shank stays the wire diameter and becomes the part that is later driven through the joint and clinched. Cold heading makes rivets fast and cheap, hundreds a minute from a coil, with almost no scrap, and the formed head has a smooth flowed grain that resists cracking when the rivet is set.

The machine cuts a blank and heads it in one place. The Press Frame takes the blow, the Wire Feed meters wire, the Cutoff and Transfer shears and transfers the blank, the Heading Die grips the shank while the Header Ram upsets the head, the Drive Train supplies the energy, the Lubrication System cools the tools, and the Control System runs and guards the cycle.

Frame and forming load

Heading a rivet means stopping a fed length of wire and squashing its end into a head, a brief high force the Press Frame absorbs without flexing. The Bed Casting carries the die and the ram ways, the Die Breast backs the die against the blow, and Tie Rod pre-load keeps the frame rigid through long production runs. A Forming Guard encloses the heading zone. Frame stiffness keeps the head height consistent, since any spring in the frame varies how far the punch closes.

Wire feed and cutoff

Wire comes off a Decoiler coil through a Straightener that removes the coil curve, because a bent shank heads off-center and will not drive straight. Feed Roll pairs then advance the length needed for the shank plus the head metal, set by the Feed Cam or a feed servo. The Cutoff and Transfer shears the blank with a carbide Cutoff Knife, and the Cutoff Quill delivers it square to the die. On machines that need it, Transfer Finger grippers timed by the Transfer Cam and returned by Coil Spring move the blank into the heading die.

Die and header ram

Heading happens between the fixed Heading Die and the moving Header Ram. The die is a Die Case holding a Grip Die that clamps the shank so only the protruding end deforms, with a carbide Head Cavity insert that gives the head its profile and a Kickout Pin that ejects the finished rivet. Facing it the Ram Body carries a Head Punch in a Punch Holder, and the ram runs square on Ram Gib strips so the punch lands true on the wire end. Changing the head cavity and punch sets the head style, round, pan, flat, or countersunk, from the same machine.

Drive

The blow draws a large force for a few milliseconds, so the Drive Train stores energy in a Flywheel kept spinning by the Main Motor through Drive Belt pairs. A Clutch and Brake couples the flywheel to the Crankshaft for each stroke, and the Pitman Arm converts the crank rotation into the straight ram stroke, all on Ball Bearing supports. This is the same flywheel principle that drives the Bolt Heading Machine and the Nut Forming Machine, letting a small motor deliver a large blow several times a second.

Lubrication and control

The die and ram run hot and heavily loaded, so the Lubrication System system feeds oil continuously. An Oil Pump lubricates the ram and crank bearings through an Oil Cooler, while Die Spray Nozzle nozzles cool and lubricate the tools each cycle, confirmed by a Pressure Sensor. The Control System cabinet sets stroke rate with an Microcontroller on a Bare PCB, a Power Supply feeds the logic, and Relay safety chains tie in the guard and clutch. A Misfeed Sensor stops the press if a blank fails to seat, which would otherwise let the punch strike an empty die. The operator works from the Operator Panel.

Materials, types, and use

Rivet headers run any metal ductile enough to flow cold: low-carbon steel, stainless, aluminium, copper, and brass for electrical and decorative rivets. The wire is sized to the shank diameter, since the shank keeps that size while only the head metal is displaced, and the cut length sets the rivet length. The output is a solid rivet with a formed head and a plain shank, ready to be driven and clinched in a joint. Head strength comes from the flowed grain: because the metal wraps continuously from shank into head rather than being cut across, the head resists splitting when the rivet is set hard. Variants of the same machine head semi-tubular and tubular rivets by adding a piercing pin in the punch, and larger or two-blow versions handle bigger or shaped heads such as truss and brazier profiles. Within the fastener family the rivet header sits alongside the cold formers that work from wire, sharing their feed, cutoff, and flywheel-driven heading, while threaded fasteners go on to a Flat-Die Thread Roller or a Roll Tapping Machine for threads that rivets never need.