Process and apparatus for making crossed-end bags from weldable material

Claim 2

A process of making crossed-end bags from weldable material, which bags have an end consisting of open crossed-end folds and an end patch welded to the edges of the open crossed-end foLds, characterized by the following process steps: a. advancing a tubing section in its longitudinal direction, and at its leading end pulling the same open and flattening the same to form open crossed-end folds; b. moving the end patch in synchronism with the tubing section and during this movement applying the same to the open crossedend folds, and joining the end patch by seam welds to those edges of the infolded corner portions which are covered by the patch; c. rotating the tubing section through 90* to its longitudinal direction; and further advancing the tubing section in its rotated orientation, in its original conveying direction; and d. joining the side edges of the end patch by seam welds to the longitudinal edges of the open crossed-end folds.

Claim 3

A process according to claim 1, characterized in that the crossed-end folds and the end patch are erected before the welding on the side edges of the end patches.

Claim 4

A process according to claim 1, characterized in that for making bags having two crossed ends, the tubing section is rotated through 180* when the first end has been closed and the second end is then pulled open and closed like the first end.

Claim 5

A process according to claim 3, characterized in that to make valved bags, the end patch of one end is shorter than the end opening and together with a valve patch partly overlapped by the end patch is applied to the open crossed-end folds in such a manner that one end of the end patch covers the edge of one infolded corner portion and one end of the valve patch covers the edge of the other infolded corner portion whereafter the seam welds are provided which join the end patch and the valve patch to the associated infolded corner portion.

Claim 6

Apparatus for making crossed-end bags from weldable material, which bags have an end consisting of open crossed-end folds and an end patch welded to the edges of the open crossed-end folds, characterized by the following features: a. a continuously revolving drum (26) provided with means for pulling open and reversely folding the leading end of the tubing section to form open crossed-end folds; b. two insulating fingers (32, 33) for each pulling-open station, which fingers are mounted on the drum and as the end of the tubing section is pulled open are moved under the free edges of the infolded corner portions (8, 9 and 8'', 9'') whereas the fingers are retracted in the peripheral direction of the drum when the end seam welds (6, 7 and 6'', 7'') have been formed; c. a gripper cylinder (18) which rotates in synchronism with the drum on a stationary axis and serves to apply the end patch or patches (3 and 4, 5) to the open crossed-end folds; d. grippers (34) which are mounted on the drum and receive the end patches from the gripper cylinder and which grip and retain the end patches and the crossed-end folds at their leading edges; e. two welding jaws (35, 36) which are associated with each pulling-open station and are mounted on the drum for axial and radial movements and are controlled to lie on the end patch or patches over the insulating fingers during the welding operation; f. a device (14'') which succeeds the drum and serves to initiate the movement of the tubing sections transversely to their longitudinal direction; and g. a welding device (15) for forming longitudinal seam welds (10, 11, 10'', 11'') on the longitudinal edges of the bag workpieces which are being handled by endless conveyors.

Claim 7

Apparatus for making crossed-end bags from weldable material, which bags have an end consisting of open crossed-end folds and an end patch welded to the edges of the open crossed-end folds, characterized by the following features: a. a continuously revolving drum (26) provided with means for pulling open and reversely folding the leading end of the tubing section to form open crossed-end folds; b. two insulating fingers (32, 33) for each pulling-open station, which fingers are mounted on the drum and as the end of the tubing section is pulled open are moved under the free edges of the infolded corner portions (8, 9 and 8'', 9'') whereas the fingers are retracted in the peripheral direction of the drum when the end seam welds (6, 7 and 6'', 7'') have been formed; c. a gripper cylinder (18) which rotates in synchronism with the drum on a stationary axis and serves to apply the end patch or patches (3 and 4, 5) to the open crossed-end folds; d. grippers (34) which are mounted on the drum and receive the end patches from the gripper cylinder and which grip and retain the end patches and the crossed-end folds at their leading edges; e. two welding jaws (35, 36) which are associated with each pulling-open station and are mounted on the drum for axial and radial movements and are controlled to lie on the end patch or patches over the insulating fingers during the welding operation; f. a device (14'') which succeeds the drum and serves to initiate the movement of the tubing sections transversely to their longitudinal direction; and g. a welding device (15) for forming longitudinal seam welds (10, 11, 10'', 11'') on the longitudinal edges of the bag workpieces which are being handled by endless conveyors.

Claim 8

Apparatus according to claim 5, characterized by a pressure fluid cylinder (52), which is secured in the drum (26) and extends parallel to the drum axis and comprises two oppositely moving pistons (50, 51), whereas the welding jaws (35, 36) are mounted on the ends of the piston rods connected to such pistons and are radially movable with respect to the drum, in conjunction with a control rail (60), which is reciprocable parallel to itself in the radial direction of The drum and is engaged by rollers (58, 59) mounted on the carriers for the welding jaws.

Claim 9

Apparatus according to claim 5, characterized in that stationary guide plates (69 to 71; 69'' to 71'') are provided, which serve to guide on both sides the erected end halves adjacent to the welding device (15) for forming the longitudinal end seam welds, which welding device is suitably provided with radiant heaters (24a, 25a, 24a'', 25a''), and double belt conveyors (72, 73; 72'', 73'') are provided, which engage the side walls of the bag close to the folded end edges.