In packaging equipment it is common and necessary to adjust a carton transport conveyor for changes in carton sizes. These carton size changes relate to carton length (machine direction), carton depth (cross machine direction) and carton width (elevation off of transport conveyor). Changes to the carton length dimension generally affect the phase relationship between adjacent drive members (sprockets) on a common drive shaft. Whereas, changes to the carton depth dimension affect the axial or transverse location of adjacent drive members on a common drive shaft. Carton width changes do not generally affect the drive system.
More particularly, it will be appreciated that in a carton transport conveyor, for example, product is transported along a rail or rails by chain-driven lugs. For example, a pair of leading lugs is respectively mounted abreast on two respective parallel leading lug chains that are driven in unison. A pair of trailing lugs is respectively mounted abreast on two other respective parallel trailing lug chains, providing a sufficient distance between the leading and trailing lugs to receive cartons therebetween for transport. Cartons are situated between the leading lugs and the trailing lugs and are transported in a machine direction such as along a rail. The leading lug chains are typically mounted on and driven by axially spaced leading lug chain drive sprockets and the trailing lug chains on axially spaced trailing lug chain drive sprockets.
To accommodate a change to handle cartons of varied length, the distance between the leading and trailing lugs must be adjusted. And to accommodate a change to handle cartons of varied depth, the axial distance between each leading lug and between each trailing lug must also be adjusted.
Several methods of phase adjustment have been used in the past. One method uses long keyways cut into the drive shaft and sprockets with radial slots mounted to keyed hubs. This method requires that each individual member be manually adjusted and calibration is crude and often not repeatable. Additionally, access for a user is awkward requiring that the user reach across the machine or walk to the backside of the machine. A slight variation would be to replace the key and hub with a spline and splined hubs.
Another method has a system where each drive member, of which there are four, is driven separately by four individual servo motors. While this method solves the access and calibration requirements it is generally cost prohibitive in many applications.
Axial adjustment has required a separate system ranging from lead screws to racks and pinion gears. Typically, two adjustment points of the conveyor are connected with a shaft to insure that both ends of the conveyor move equally. Lead screws have also been used for multiple point adjustment, usually requiring a chain or belt to connect two or more screws in order to synchronize the movement.
There is a need, therefore, in the area of carton transport conveyors for apparatus to facilitate the phase and axial adjustment of a transport drive system. Preferably, such apparatus would allow adjustments to be made from a single point at the front side of a carton transport conveyor.