Abstract: A heat sealing apparatus for sealing together two layers of heat softenable plastics material, for example two sides of the top of a bag or sack, comprising a pair of rollers arranged to nip said layers together to form a seal after they have been softened, means loading one roller towards the other roller and permitting said one roller to be urged away from said other roller against the load exerted by said loading means on passage of layers of plastics material between the rollers, and stop means arranged such that said loading means exerts a reduced loading on the rollers in the absence of layers of plastics material to be sealed.

Abstract: A hot air heat sealing apparatus for sealing together two layers of heat softenable plastics material comprising a fan, ducting arranged to divide the air stream from the fan into at least two flows, a heater disposed in the path of one of said flows, means by which air heated by the heater is directed in use onto the layers of plastics material thereby to soften said layers at a region thereof where they are to be sealed together, a pair of rollers arranged to nip the softened layers together to produce a seal, one of said pairs of rollers being mounted for pivotal movement radially relative to the other roller of said pair, means for pivotally moving said one roller whereby the nipping pressure exerted by the rollers can be varied and plastics material layers of different thickness can be accommodated and means for varying the inclination of the axes of the rollers relative to one another, whereby said axes can be brought into parallelism, and guide means disposed in the path of the other of said flows for