Web registration method and apparatus

Claim 2

In a packaging process comprising intermittently feeding a web of thermoplastic film having spaced, repeat indicia formed thereon, whereby said film web is formed in a container forming stage, the container is filled in a container filling stage and the container is closed in a container closing stage, an improved method of compensating for predetermined deviations of said indicia, said method comprising the steps of: a. detecting said predetermined deviation with probe means; b. clamping said film web on either side of a container forming station between two horizontally spaced apart clamping members when the web is stopped; and c. longitudinally displacing one of said clamping members with respect to the other, thereby stretching the film web by a predetermined amount to compensate for the predetermined deviation detected by said probe means.

Claim 3

The method of claim 1 including the further step of heating a narrow transverse band of said film web prior to longitudinally displacing said clamping member whereby stretching of the film occurs only across the heated band.

Claim 4

In a packaging apparatus comprising a container forming station, a container filling station and a container closing station, having feed means for intermittently advancing on a timed basis a web of thermoplastic film through said stations, said film having spaced repeat indicia printed thereon, probe means for detecting a predetermined amount of deviation of said indicia, and improved means for centering said indicia when the indicia has deviated by said predetermined amount, said improvement comprising: a first clamping means and associated support element, said first clamping means being mounted for longitudinal displacement along said support element, a second clamping means and associated support element, said second clamping means being fixably mounted to its support element, one of said clamping means being located upstream of said container forming station and the other of said clamping means being located downstream of said container forming station, and including means controlled by said probe means for simultaneously actuating both of said clamping means to clamp said thermoplastic film therebetween and means controlled by said probe for displacing said first clamping means longitudinally of said second clamping means when the film is stopped, thereby stretching the film by a predetermined distance to compensate for the predetermined deviation detected by said probe means thereby centering the indicia.

Claim 5

In a packaging apparatus comprising a container forming station, a container filling station and a container closing station, having feed means for intermittently advancing on a timed basis a web of thermoplastic film through said stations, said film having spaced repeat indicia printed thereon, probe means for detecting a predetermined amount of deviation of said indicia, and improved means for centering said indicia when the indicia has deviated by said predetermined amount, said improvement comprising: a first clamping means and associated support element, said first clamping means being mounted for longitudinal displacement along said support element, a second clamping means and associated support element, said second clamping means being fixably mounted to its support element, one of said clamping means being located upstream of said container forming station and the other of said clamping means being located downstream of said container forming station, and including means controlled by said probe means for simultaneously actuating both of said clamping means to clamp said thermoplastic film therebetween and means controlled by said probe for displacing said first clamping means longitudinally of said second clamping means when the film is stopped, thereby stretching the film by a predetermined distance to compensate for the predetermined deviation detected by said probe means thereby centering the indicia.

Claim 6

The improvement of claim 3 wherein each of said clamping means comprises a horizontally disposed U-shaped component, the upper limb of said component extending transversely of and above the film web, the lower limb of said component extending transversely of and below the film web, a pneumatically or hydraulically operable piston and associated plunger vertically disposed in said lower limb and a thrust rod interconnecting the clamping means whereby upon detection by said probe means of said predetermined amount of deviation said plungers are simultaneously displaced vertically upward thereby clamping the film between the plunger and the upper limb of the U-shaped component.

Claim 7

The improvement of claim 4 further including a pressure plate disposed between the plunger and the film web.

Claim 8

The improvement of claim 3 wherein said probe means is a photo-electric cell.

Claim 9

The improvement of claim 3 wherein the means for longitudinally displacing the first clamping means comprises a horizontally disposed piston and cylinder means located on each end of the support element, one of said piston and cylinder means displacing the clamping means to effect stretching of the film upon detection by said probe means of said predetermined amount of deviation and the other of said piston and cylinder means returning the clamping means to its rest position when the film has been stretched by the predetermined amount.

Claim 10

The improvement of claim 3 further including heating means located between the forming means and the first clamping means and disposed transversely of the film web, whereby a narrow transverse band of the film web is heated, stretching of the film occurring only across said heated band.