US3853040A

US3853040A - Process and apparatus for making crossed-end bags from weldable material

Info

Publication number: US3853040A
Application number: US00353973A
Authority: US
Inventors: F Achelpohl
Original assignee: Windmoeller and Hoelscher KG
Current assignee: Windmoeller and Hoelscher KG
Priority date: 1972-05-02
Filing date: 1973-04-24
Publication date: 1974-12-10
Anticipated expiration: 1991-12-10
Also published as: FR2183497A5; JPS4942472A; DE2221376B2; IT982832B; NL7305914A; ES414214A1; DE2221376A1

Abstract

The process and apparatus serve to make bags which have an end consisting of open crossed-end folds and an end patch welded to the edges of the crossed-end folds. A tubing section is advanced in its longitudinal direction and at its leading end is pulled open and flattened to form open crossed-end folds. The end patch is moved in synchronism with the tubing section and during this movement is applied to the open crossed-end folds. The end patch is joined by seam welds to those edges of the infolded corner portions which are covered by the patch. The tubing section is then moved transversely to its longitudinal direction. The side edges of the end patch are joined by seam welds to the longitudinal edges of the open crossed-end folds.

Description

United States Patent 1 Achelpohl PROCESS AND APPARATUS FOR MAKING CROSSED-END BAGS FROM WELDABLE -MATERIAL [75] Inventor: Fritz Achelpohl, Lengerich of Westphalia, Germany [73] Assignee: Windmoller & Holscher, Lengerich of Westphalia, Germany [22] Filed: Apr. 24, 1973 [21] Appl. No.: 353,973

[30] Foreign Application Priority Data Finke et al. 93/35 SB X 1 Dec. 10, 1974 Primary Examiner-Roy Lake Assistant Examiner-James F. Coan Attorney, Agent, or Firm-Fleit & Jacobson [5 7 ABSTRACT The process and apparatus serve to make bags which have an end consisting of open crossed-end folds and an end patch welded to the edges of the crossed-end folds. A tubing section is advanced in its longitudinal direction and at its leading end is pulled open and flattened to form open crossed-end folds. The end patch is moved in synchronism with the tubing section and during this movement is applied to the open crossedend folds The end patch is joined by seam welds to those edges of the infolded corner portions which are covered by the patch. The tubing section is then moved transversely to its longitudinal direction. The side edges of the end patch are joined by seam welds to the longitudinal edges of the open crossed-end folds.

7 Claims, 14 Drawing Figures Pmmw wmw 3.853.040

SHEET ?.0F 6

PATENIED DEC] 01974 SHEET Q 0F 6 PATENTEU DEC 1 01974 SHEET 5 BF 6 PROCESS AND APPARATUS FOR MAKING CROSSED-END BAGS FROM WELDABLE MATERIAL This invention relates to a process and 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.

According to the Opened German Application 1,41 1,863, it is known in the manufacture of such bags intermittently to advance tubing sections made of synthetic thermoplastic sheeting transversely to their longitudinal direction and to subject said tubing sections, when they are at a standstill in stationary processing stations, to the required processing, by which the tubing is pulled open at one or both ends and is flattened so as to form infolded corner portions so that open crossed-end folds are formed there, whereafter an 'end patch is applied to said fold and is first welded to those edge portions of the infolded corner portions which are overlapped by the patch and is subsequently welded to the side edges of the crossed-end folds, which side edges are also covered by the patch.

Because the relatively large tubing sections are intermittently advanced and the tools in the several processing stations are reciprocated with necessarily large strokes, the bag-making machine cannot operate at a high rate so that this known machine is not sufficiently economical.

In another process, which is known from the Opened German Application 1,924,109, the transversely extending tubing sections are continuously advanced and the processing tools are carried by carriages, which are reciprocated along paths extending in the direction of advance of the tubing sections and advance in synchronism with the tubing sections. The tubing sections are processed during the synchronized advance of the tool carriage. This processing is substantially similar to the processing which hasbeen described with reference to the Open German Application 1,411,863. In view of the welding times required and of the control of the large mass acceleration forces involved in the reciprocation of the heavy tool carriages, this process can be performed at a satisfactorily high rate only if the tool carriages carry a plurality of complete tool sets 4 the Opened German Application 1,924,109 discloses six to eight of such sets which have the same pitch as the tubing sections so that six to eight tubing sections can be processed at the same time during the synchronized advance of the tool carriage. Such apparatus involves not only a very considerable expenditure of expensive tools but also. a large space.

It is an object of the invention to provide a process and apparatus for manufacturing the crossed-end bags to the open crossed-end folds, and the end patch is joined by seam welds to those edges of the infolded corner portions which are covered by the patch;

c. the tubing section is then moved transversely to its longitudinal direction; and

d. the side edges of the end patch are joined by seam welds to the longitudinal edges of the open crossedend folds. v

In the process, there is no need for an intermittent movement of the tubing sections nor for heavy tool carriages which are advanced with the tubing sections and are retracted after a processing step, nor for an expensive provision of similar tool sets operating in synchronism. In the process according to the invention, the bags can be processed with high accuracy and at a high rate and while they are moved continuously.

To move the tubing sections transversely to their longitudinal direction, each tubing section is preferably rotated through whereas the direction of movement remains unchanged. It will also be desirable to erect the crossed-end folds and the end patch for the welding of the side edges of the end patch so that the formation of the longitudinal seam welds on that half of the end portion which previously engaged the remainder of the bag workpiece.

When it is desired to use the process accordingto the invention to make bags having two crossed ends, the tubing section is desirably rotated through when the first end has been closed and the second end is then pulled open and closed like the first end. When valved bags are to be made in this case, the end patch of one end may be shorter than the end opening and together with a valve patch partly overlapped by the end patch may be 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 with join the end patch and the valve patch to the associated infolded corner portion.

In a preferred embodiment of the invention, the tubing sections are provided at theopening-defining edges with short slitsbeforethe tubing sections are pulled open so that inwardly extending, free, rectangular end portions are formed at the infolded corner portions as the latter are pulled open. Such tubing sections can be processed in a much simpler manner by the process according to the invention; this will be referred to more in detail hereinafter.

The apparatus proposed according to the invention for carrying out the process according to the invention is characterized by the following features, which are partly known per se:

a. A continuously revolving drum provided with means for pulling open and reversely folding the leading end of the tubing section to form open crossed-end folds;

b. the provision of two insulating fingers 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 whereas the fingers are retracted in the peripheral direction of the drum when the end seam welds have been formed;

c. a gripper cylinder which rotates in synchromism with the drum on-a stationary axis and serves to apply the end patch or patches to the open crossedend folds;

cl. grippers 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 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 which succeeds the drum and serves to initiate the movement of the tubing sections trans versely to their longitudinal direction; and

g. a welding device for forming longitudinal seam welds on the longitudinal edges of the bag workpieces which are being handled by endless conveyors.

Stationary cams disposed laterally of the drum may be used to control the welding jaws of feature e) but such means for driving the welding jaws would involve certain difficulties in the arrangement of the required control linkages and in their change when other bag sizes are to be made. For this reason it is another feature of the invention to provide welding jaw drive means which are much more favorable as regards space requirement and simplicity of adjustment and which comprise a pressure fluid cylinder, preferably a pneumatic cylinder, which is secured in the drum and extends parallel to the drum axis and comprises two oppositely moving pistons, whereas the welding jaws 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, which is reciprocable parallel to itself in the radial direction of the drum and is engaged by rollers mounted on the carriers for the welding jaws.

Where narrow crossed ends are to be made, it may be desirable in accordance with the invention to provide stationary guide plates for guiding on both sides the erected end halves adjacent to the welding device for forming the longitudinal end seam welds, which welding device is suitably provided with radiant heaters, and to provide double belt conveyors, which engage the side walls of the bag close to the folded end edges.

The invention will be explained more fully hereinafter with reference to the drawing, in which FIG. 1 is an illustrative embodiment of a bag mad according to the invention,

FIG. 2 is a sectional view taken on line Il--Il in FIG. 1,

FIG. 3 is a sectional view taken on line IIIIII in FIG.

FIG. 4 is a sectional view taken on line IV-IV in FIG. 1,

FIGS. 5a and 5b are a diagrammatic elevation showing the bag-making machine used to make the bag according to FIGS. 1 to 4.

FIGS. 6a and 6b illustrate the processing steps carried out by the bag-making machine shown in FIGS. 5a and 5b;

FIG. 7 is an enlarged side elevation showing the endlaying device of the bag-making machine of FIG. 5a;

FIG. 8 is a sectional view taken on line VIII-VIII in FIG. 7.

FIGS. 9 to 11 show three typical processing steps of the end-laying device of FIGS. 7 and 8;

FIG. 12 is a' diagrammatic transverse sectional view showing a welding device for joining the end patches and the valve patch to the longitudinal edges of the crossed-end folds.

The bag 1 shown in FIG. 1 has a closed lower end and an upper end provided with a filling valve 2. Each end comprises open crossed-end folds, which are closed by an end patch 3 (lower end) and by an end patch 4 and a valve patch 5 overlapped by the end patch 4 (top end). The ends of the

patches

3, 4, 5 are joined by seam welds 6, 7; 6, 7' (FIGS. 2 and 3) to the inner edges of the infolded corner portions 8,9 and 8', 9, respectively. The sides of the

patches

3, 4, 5 are joined by seam welds l0, l1 and 10', 11', respectively, to those longitudinal edges of the crossed-end folds which extend between the infolded corner portions. As a result, the bag is airtightly sealed at its ends. The filling valve 2 is readily formed by the overlap between the end patch 4 and the valve patch 5; this is particularly distinctly apparent from FIG. 2.

The bag-making machine shown in FIGS. 5a and 5b and described hereinafter serves for the mass production of the bag shown in FIGS. 1 to 4.

A cross cutter 12 of known type serves to cut tubing sections from a tubing A of synthetic thermoplastic sheeting. An end-laying device 13 comprises a continuously revolving drum 26 and forms open crossed-end folds at the leading end of each tubing section. The drum 26 is provided with means for applying the end patch 3 (FIG. 1) to the open crossed-end folds and with means for joining the ends of the end patch to the inside edges of the infolded corner portions of the crossed-end folds by seam welds 6', 7' (FIG. I). The end-laying device 13 is succeeded by a turning device 14, preferably according to the German Pat. No. 1,586,347, which has been assigned to the same assignees as the present invention, turns the bag workpieces through l (twice through in a horizontal plane. A second end-laying device 13 is similar to the endlaying device 13 but is provided with means for the simultaneous application of an end patch 4 and of a valve patch 5 (FIG. 1), which is overlapped by the end patch 4, to the open crossed-end folds formed by the endlaying device 13, and joins one end of each of these

patches

4, 5 to the infolded corner portions of the crossed-end folds by the seam welds 6, 7. A turning device 14 succeeds the end-laying device 13' and serves to turn the bag workpiece through 90 in a horizontal plane. The turning device 14' is succeeded by a welding device 15 for joining the end patches 3, 4 and the valve patch 5 to the longitudinal edges of the crossed-end folds by the longitudinal seam welds 10, 11; l0, 11 (FIG. 1).

FIGS. 6a and 6b illustrate the mode of operation of the bag-making machine shown in FIGS. 5a and 5b. In the cross cutter l2, tubing sections S in the length re-. quired for the manufacture of respective bags are cut from a tubing A, which is continuously advanced by a feed roller pair 16. By means of the feed rollers 17, the tubing sections S are advanced further and fed to the end-laying device 13, the design of which is apparent from FIGS. 7 and 8. In the end-laying device 13, the leading end of the tubing section is pulled open and is flattened to form open crossed-end folds. By means of the gripper cylinder 18, the end patch 3 is then applied to the open crossed-end folds and by means of

lateral welding jaws

35, 36, shown in FIGS. 7 and 8, is subsequently joined by seam welds 6', 7 to the infolded corner portions 8', 9' of the crossed-end folds. (See also FIGS. 1 and 3). The end patches 3 are cut from a sheeting web B, which is advanced from the supply roll 19.

The bag workpiece now enters the turning device 14 and is fed by the latter to the second end-laying device 13'. By the turning device 14, the bag workpiece is turned in a horizontal plane through 180 in the direction of arrow so that the other, still open end of the tubing section is now the leading end. In the end-laying device 13', the tubing section end is pulled open and is flattened to form open crossed-end folds. By means of the gripper cylinder 18', the end patch 4 and the valve patch overlapped by the end patch 4 are then applied to the open crossed-end fold. The

patches

4, 5 are subsequently joined by seam welds 6, 7 to the infolded corner portions 8, 9 of the crossed-end folds. The end patches 4 and the valve patches 5 are cut from the sheeting webs B and V, which are advanced from the supply rolls 19 and 26. The latter are laterally offset from each other so that the sheeting webs move to the cutting device and the gripper cylinder 18 so as to provide for the desired overlap x of the

patches

4, 5.

From the end-laying device 13', the bag workpiece enters the turning device 14, which turns the bag workpiece through 90 so that it is advanced transversely to its longitudinal direction. During this continuous advance, the two folded ends are erected by the deflecting plates 21, 21 from a flattened position to an upright position and are transferred to the pairs of double belt conveyors 22, 23; 22', 23', which move the bag workpiece having folded ends through the welding device 15, which comprises pairs of

radiant heaters

24, 25; 24', 25' and in which the end patches 3, 4 and the valve patch 5 are joined to the longitudinal edges of the crossed-end folds by the longitudinal seam welds 10, l1; 11'. These longitudinal seam welds produced by radiant heaters are flush with the longitudinal edges of the bag end. This is different from the showings of FIGS. 1 and 4, where longitudinal seam welds are shown which have been made with the aid of hot rolls or hot tape.

. When it is desired to make narrow crossed ends, the space requirement may be reduced if the bag workpieces are advanced to the welding device in the manner shown in FIG. 12. Each of the two halves of the crossed-end folds at each end are angled through 45 upwardly and downwardly, respectively, from the plane in which the bag workpieces are advanced so that these two halves at each end include an angle of 90. In this orientation, the crossed-end halves are guided by

stationary guide plates

69, 70, '71 and 69, 70', 71. respectively, as they move past the radiant heaters 24a, a or 24a, 25a'.. Only one pair of

conveyor belts

72, 73 and 72', 73' is required on each side for advancing the bag conveyors and this pair of conveyor belts engages the side walls of the bag workpiece closely beside the

guide plates

69, 70 or 69', 70', i.e., closely beside the folded edges of the crossed ends.

The turning device 14, the end-laying device 13, and the welding device22-25 may be omitted if the bags are to be closed only at one end.

The end-laying

device

13 or 13 is shown on a larger scale in FIGS. 7 and 8. The device comprises a continusection at its leading open end. The diameter of the gripper cylinder and its angular position relative to the drum 26 are selected so that the vacuum strip 29 of the cylinder always rolls on one of the vacuum strips 27, 27', 27" of the drum. Associated with the vacuum strip 27 are a lateral pair of

grippers

30, 31, a pair of insulating

fingers

32, 33, a number of grippers 34 on the leading edge of the vacuum strip, and a pair of

welding jaws

35, 36. The pair of

lateral grippers

30, 31 are arranged to engage the tubing section S at its side edges and to retain it on the drum 26 at the point where the folding of the end is to be initiated (see FIGS. 9 and 10).

As is apparent from FIGS. 8, 9, and 10, the pair of insulating

fingers

32, 33 are arranged on the drum 26 and controlled to move over the vacuum strip 27 (arrow 44) opposite to the direction of rotation of the drum and to engage the vacuum strip 27 adjacent to the corner portions 8, 9, and 8', 9', respectively, as the same are infolded. The pair of insulating fingers are secured to levers 37, 38 and, as is apparent from FIG. 7, are curved like arcs of a circle in accordance with the periphery of the drum 26. the levers 37, 38 have a common pivot 66, which is mounted at one end in bellcrank levers 39 and at the other end in links 40, which are pivoted on aligned

pivots

41, 42 mounted on the drum. A stationary pusher cam 43 imparts to the levers 37, 38 a pivotal movement in the peripheral direction of the drum (arrow 44) as the latter rotates. At the same time, the stationary pusher cam 45 imparts to said levers an additional radial movement (arrow 46) by means of the bell-crank lever 39. The

pusher cams

43, 45 are shaped so that the

fingers

32, 33 move from the end position shown on the left in FIG. 7 to the end position shown at the top in FIG. 7 as the end of the tubing section is pulled open. This movement of the

fingers

32, 33 is indicated in FIG. 9.

The

welding jaws

35, 36 are provided with pairs of guide rods 46, 47, which are mounted in carriers 48, 49 to be radially displaceable relative to the drum 26. The carriers 48, 49 are mounted on the end of the piston rods associated with two oppositely moving pistons 50, 51, which slide in the common pneumatic cylinder 52, which is parallel to the axis of the drum 26. Compressed air is admitted at 53 between the pistons 50, 51 through a bore, not shown, in the drum shaft and a control valve, not shown, which is mounted on said shaft. By this

pneumatic actuator

50, 51, 52, and the retracting springs 34, 55, the

welding jaws

35, 36, are moved from their outer position, shown in solid lines, to the inner position, shown in dash-dot lines, in a direction which is parallel to the axis of the drum; this is indicated in FIG. 8. In said inner position, the

welding jaws

35, 36 are exactly over the insulating

fingers

32, 33. The pairs of radial guide rods 46, 47 carry

rollers

58, 59, which by springs 56, 57 are urged against a control bar 60, which is parallel to the axis of the drum 26. This control bar is movable in parallel to itself and is linked to the drum, e.g., by parallel-

motion links

61, 62. By means of an actuator 64, which is pivoted at 63 to the control bar 60, the latter is radially reciprocated to impart to the welding jaws 35, 36 a radial movement with respect to the drum in that the bar-60 moves the pairs of

welding jaws

35, 36 from their inner position, shown in dash-dot lines in FIG. 8, radially against the shell of the drum so that they engage the pairs of insulating

fingers

32, 33 and lift from the latter after an interval of time, which is independent of the machine cycle and controlled by a timer. Thereafter, the

fingers

32, 33 re turn to their outer position, shown in solid lines.

As has already been indicated with reference to FIG. 5, a gripper cylinder 18 is associated with the drum 26 and feeds the end patch 3, 4 and, if desired, the valve patch to the bag workpiece which is disposed on the drum. Finally, another gripper cylinder 65 for removing the bag workpiece and for forwarding it to the turning device 14 is associated with the drum 26.

Entering the end-laying device 13, the tubing section S is gripped at its leading open end by the vacuum strip 29 of the gripper cylinder 28, and as the tubing section S rolls on the drum 26 the tubing section S is engaged on the other side face by the vacuum strip 27 of the drum 26. As a result, the leading end is pulled open. The point where the end folds begin is controlled by the

lateral grippers

30, 31, which engage the tubing section at both'side edges and retain it on the drum. During this operation, the insulating

fingers

32, 33, as shown in FIG. 9, move into the pulled-open end of the tubing section, which is folded to form the open crossed-end folds, including the infolded corner portions 8', 9', and is flattened on the shell of the drum and retained by the insulating fingers. The vacuum action of the vacuum strip 29 is interrupted in time while the vacuum strip 27 continues to retain the tubing section on the shell of the drum. The flattening of the crossed-end folds by the insulating

fingers

32, 33 may be assisted by a stationary folding plate 67 (FIGS. 7 and 9), which extends between said fingers. In the processing of tubing sections which at their open ends are provided with short slits, the

fingers

32, 33 as they advance in direction 44 readily move under the inner ends of the infolded corner portions, as is shown in FIG. 9. These inner ends are defined by the slits. As the folding operation continues, the inner ends of the infolded corner portions come to rest on the insulating

fingers

32, 33, as is shown in FIG. 10. If tubing sections lacking said short slits were to be processed, the insulating fingers would have to perform a transverse outward movement in addition to the movement in direction 44 so that the fingers move under the infolded corner portions when the end has been folded. Besides, the insulating fingers would require outwardly directed, lateral extensions, which move under the infolded corner portions during the transverse movement. The control of such additional transverse movement of the insulating fingers involves a high expenditure.

The described folding to form open crossed-end folds is performed during the rotation of the drum 26 from the gripper cylinder 28 to the gripper cylinder 18. The gripper cylinder 18 rotating in synchronism with the drum 26 now lays the end patch 2 or, if the end is to be provided with a filling valve 2, the end patch 4 and the valve patch 5 overlapped by the end patch 4, on the open crossed-end folds. At their leading edge, these edges and the leading edge of the crossed-end folds are gripped and exactly held in position by the grippers 34,

which are mounted on the drum. As the rotation of the drum is continued, the

welding jaws

35, 36 move from their outer position shown in solid lines in FIG. 8 over 5 and beyond the infolded corner portions of the end folds into their inner position, shown in dotted lines, and in said inner position engage the inner ends of the infolded corner portions, which inner ends rest on the insulating

fingers

32, 33, and the jaws also engage the ends of the end patches 3, 4 and of the valve patches 5, which ends overlap said infolded corner portions. Said patches are thus joined to the infolded corner portions by the seam welds 6, 7 and 6, 7' (FIG. 11). The insulating

fingers

32, 33 prevent a welding of the infolded corner portions to the sides of the bag ends. This welding operation is performed as the drum rotates from the gripper cylinder 18 to the gripper cylinder 65. Shortly before the end folds arrive at the gripper cylinder 65, the welding jaws 35, 36'are returned to their outer position and the insulating

fingers

32, 33 are returned to their initial position, shown on the left in FIG. 7, and the

lateral grippers

30, 31 are opened. The workpiece which is now retained on the drum only by the grippers 34 is then received by the gripper cylinder 65 moving in synchronism and is transferred by the latter to succeeding conveyors 68, which feed the workpiece to the

turning device

14 or 14, which is shown in FIGS. 5a and 5b. when the end has been finished to that extent and erected upright by the deflecting plates 21, 21, the end is squared along the lines 74, 75, shown in dotted lines in FIG. 11, by a squaring device 76, 77 shown in FIG. 5 before the end moves into the welding device 15, in which the longitudinal seams 10, ll, 11' are formed. As a result, the crossed end leaving the welding device 15 has the configuration shown on the right in FIG. 5b and in FIG. 1.

What is claimed is:

1. 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 tub ing section and during this movement applying the same to the open crossed-end 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

I d. joining the side edges of the end patch by seam end folds.

welds to the longitudinal edges of the open crossedhas been closed and the second end is then pulled open and closed like the first end.

4. A process according to claim 3, characterized in that to make valved bags, the end patchof 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.

5. 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; I

b. two insulating fingers (32, 33) for each pullingopen 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;

0. 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, 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, ll, l0, 11) on the longitudinal edges of the bag workpieces which are being handled by endless conveyors.

6. 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.

7. 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.

Claims

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

7. 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.