Can Seaming Machine

Overview

A can seaming machine, also called a seamer or a can closer, attaches the lid to a filled can by folding the lid and the can body together into an airtight double seam. It does not weld or glue anything. It rolls metal over metal twice so that the curl of the lid and the flange of the body interlock into five layers of tin plate compressed around a ring of sealing compound. That double seam is what keeps food sterile for years, so the geometry it forms is held to hundredths of a millimetre. The machine takes a filled can with a loose lid resting on top, lifts the can up against a chuck, and rolls the seam closed while the can spins, all in a fraction of a second per can.

The machine is built on the Machine Frame, which carries the Seaming Head over the Lifter System. On a rotary machine the Seaming Turret carries several heads in a circle, the Lid Feed System drops one lid onto each can, and the Can Handling times cans in and out while the Main Drive System keeps every motion in step under the Control System.

The double seam and the seaming head

The seam is formed by the Seaming Head in two distinct operations. The can is held against the Seaming Chuck, which fits inside the lid and gives the rolls something solid to press against. Then the First Operation Roll moves in. Its profile has a deep, round groove that curls the edge of the lid under the body flange and tucks the two together without flattening them. A moment later the Second Operation Roll, which has a shallower and flatter groove, presses that loose hook tight into the finished seam. Using two rolls with two profiles is what lets the machine fold metal sharply without splitting it. Each roll rides on a Seaming Roll Body turning on a Seaming Roll Bearing, and each is carried by a Roll Lever Arm that the Seaming Cam swings in and out at exactly the right point in the can's rotation. The Chuck Spindle spins the chuck and the can together so the rolls work the full circumference.

Lifting and clamping the can

A can cannot be seamed unless it is pressed firmly up into the chuck with the right force, so the Lifter System does that for every can. Each station has a Lifter Base Plate that the can sits on, pushed up by a Lifter Push Rod that rides over the Lifter Cam Track. The cam profile raises the plate as the can reaches the seaming position and lowers it after the seam is done. A Lifter Spring sets the clamping load, which matters because too little force lets the can slip and skid the seam while too much can crush a light gauge can. The lift force, the chuck fit, and the roll positions all have to agree, and a seamer is set up by a technician who measures finished seams and adjusts these together.

The turret and how cans flow through

On a high-speed machine the Seaming Turret turns continuously and carries the seaming heads around with it, so a can is seamed while it travels rather than at a stop. The Turret Table rides on the Turret Center Shaft through a Turret Main Bearing, and a Turret Index Gear keeps the turret in phase with the rest of the drive. Cans reach the turret through the Can Handling section. A Infeed Timing Screw spaces the incoming cans to the station pitch, the Infeed Star Wheel hands each one to a lifter plate, and after seaming the Discharge Star Wheel pulls the closed can out onto the Discharge Conveyor. A Can Guide Rail keeps the cans upright through every transfer.

Feeding the lids

Each can needs one lid placed squarely on its flange just before it reaches the chuck, and the Lid Feed System does this. Lids are stacked in the Lid Magazine, and the Lid Separator uses a Separator Knife to peel exactly one lid off the bottom of the stack so two never feed at once. That single lid slides down the Lid Transfer Chute and is set on the can, sometimes with help from a Vacuum Pickup Cup that holds it flat and centred. The Lid Feed Cam times the whole motion to the turret. A lid that lands off-centre makes a cocked seam that leaks, so the feed is one of the most carefully timed parts of the machine.

Drive, lubrication, and control

Every cam, roll, and star wheel runs off one Main Drive System so the motions never drift apart. A Main Drive Motor drives the Main Cam Shaft through a Gearbox Housing and a Helical Gear Pair, and a Clutch-Brake Unit lets the machine stop within one revolution if a jam is sensed. Because the seaming heads work hard and fast, the Lubrication System system runs constantly: a Lubrication Oil Pump draws from the Oil Reservoir through a Oil Filter Element and feeds oil to the cams and bearings through a Oil Distributor Block and many a Oil Supply Line. The Control System runs the sequence from the Control Cabinet, lets the operator work through the Operator Panel, sets speed with the Variable Frequency Drive, and watches a Proximity Sensor at each station so a missing lid or a double feed stops the line before a bad can is made. A correctly set seamer makes hundreds of identical airtight seams a minute, which is why it sits at the end of nearly every food and beverage canning line.