Package strapping device with pallet sensing means

Abstract

A package strapping machine for strapping a package to a pallet, which pallet is usually constructed from lumber and is of standard shape or configuration. The pallet comprises generally a supporting platform for the package with longitudinally parallel extending stringers secured to the underside of the supporting platform. The strapping machine is provided with a strapping station where the package is tied to the pallet and is so constructed that a strap is carried beneath the stringers and through a strap ring including an arch around the package if the pallet is facing in one direction, because a pallet position sensing means, such as a ray of light which is provided at one side of the pallet, cannot pass through the solid stringers to a photo-sensitive device located at the other side of the pallet. However, if the pallet is turned 90.degree. so that the voids between the stringers which extend completely through the pallet structure are positioned 90.degree. from aforementioned position, the ray of light at one end then passes through the void and impinges upon a light-sensitive device at the other end of the pallet. The strap then will not be carried underneath the stringers, but instead a lower track portion of the strap ring will be removed so that a strap conveying sword and a cooperating sword strap corner are moved to extended positions to pass the strap directly beneath the platform and carry the strap around the pallet and the package with the strap contacting the underside of the platform and the package thereon rather than the underside of the stringers. After the strapping operation is completed, the sword and sword corner are retracted and the U-shaped lower track portion is moved into the position to carry the strap beneath the stringers when the next strapping operation is manually started assuming that the light sensitive means cannot be activated. The lower track portion consists of two lower track corners with a horizontal portion connected therebetween, forming a U-shape, the entire lower track assembly being mounted so as to be movable at a 90.degree. angle to the plane of the strap travel. The lower track is preferably moved by a reciprocable compressed air cylinder, as is the sword corner. The sword is preferably moved by a reversable air motor. The electrical circuitry is such that the strapping mode established at the time the pallet is passing the strapping stations, i.e., the "sword" mode or the "lower track" mode, is the mode which will be locked in for that particular cycle. However, if a pallet is passing through the strapping station with the stringers facing in a direction to intercept the light ray to the light sensitive means, which is usually an electric eye, and the strapping operation is manually initiated, the sword mode operation cannot take place. The operation of the horizontal lower track is controlled by an electric circuit including switches and relays. The sword and the cooperating sword corner are positioned to carry the strap between the stringers beneath the pallet-supporting surface and are also controlled by switches and relays which are energized in response to manual initiation but, as stated, are dependent for operation upon energization of a pallet position sensing means such as a light energized electric eye.

Dependencies are inferred from the claim text.