EP0454410A2

EP0454410A2 - Bag forming machine

Info

Publication number: EP0454410A2
Application number: EP91303619A
Authority: EP
Inventors: John Dalton Griffith
Original assignee: Griffith Textile Machines Ltd
Current assignee: Griffith Textile Machines Ltd
Priority date: 1990-04-24
Filing date: 1991-04-23
Publication date: 1991-10-30
Also published as: GB9009143D0; EP0454410A3

Abstract

A bag forming machine including folding means (10,11) for folding a web of fabric (66) to form two superimposed layers of fabric joined along one side by a fold, holding means (20,21) for holding the folded fabric along the side edge opposite the fold, severing means for severing the folded fabric from the web of fabric material, and sewing means (40,41) for seaming the folded fabric along the edge opposite said fold and along one end edge extending between the fold and said side edge.

Description

The present invention relates to a bag forming machine and in particular to a machine for forming bags from a leno weave fabric.
Such bags are commonly used to store agricultural products for example vegetables. These bags are usually formed by folding fabric to form two superimposed layers which are then seamed along one side edge and one end edge.
Machines for folding the fabric are known but the folded fabric is then manually seamed on a conventional sewing machine.
It is an object of this invention to automate the sewing operation and incorporate the automatic folding and cutting operations in the same machine.
According to one aspect of the present invention there is provided a bag forming machine including folding means for folding a web of fabric to form two superimposed layers of fabric joined along one side by a fold, holding means for holding the folded fabric along the side edge opposite the fold, severing means for severing the folded fabric from the web of fabric material, and sewing means for seaming the folded fabric along the edge opposite said fold and along one end edge extending between fold and said side edge.
Preferably the folding means comprises at least one folding arm extending transversely of the path of feed of said web material, the folding arm being mounted on a shaft and being arranged parallel thereto, the shaft including gripping means, preferaby comprising at least one row of pins, for gripping an end edge of the web fabric such that rotation of the shaft causes the folding arm to move about a circular path to engage the web fabric and then on continued movement along the circular path of travel to simultaneously fold and draw the web fabric to form two superimposed layers of fabric and also bring a transverse portion of the fabric into contact with the shaft for severance.
Preferably at least one pair of diametrically opposed folding arms are provided.
The holding means preferably comprises a support arm located parallel to the shaft axis and arranged to move from a remote location whereat it lies outside said circular path of travel to a fabric engaging position adjacent to said shaft, the support arm including fabric gripping means, preferably in the form of pins, for gripping the fabric during severance and preferably seaming.
Preferably the severance means comprises an electric heater such as a heater wire which extends along the shaft to engage said transverse fabric portion, the holding means preferably being arranged so that during its movement from the fabric engaging position to the seaming position, it moves the fabric into contact with the heater wire and also the gripping means on the shaft.
Preferably the seaming means comprises two sewing machines, one sewing machine being arranged to travel in the same direction and the other sewing machine being arranged to travel in a transverse direction to said shaft for seaming the end edge.
Various aspects of the present invention are hereinafter described with reference to the accompanying drawings, in which -

Figure 1 illustrates the cut and folded fabric prior to seaming;
Figure 2 illustrates a completed bag
Figure 3 (a) to (d) are schematic elevation views of a machine according to the present invention showing different stages in the cycle of operations;
Figure 4 (a) to (d) are schematic plan views of the machine shown in Figure 3 showing different stages in the cycle of operation;
Figure 5 is a more detailed part elevation view of the fabric holding means.

A bag or container 100 produced by a machine according to the present invention is illustrated schematically in Figure 2. The bag 100 is formed from a length of material preferably a woven fabric such as leno weave, which is folded to form two superimposed layers 101,102 joined by a fold 103. The layers 101,102 are seamed together along one side edge 104 opposite the fold 103 and along one end edge 105 to form the bag.
The material of the bag is folded and cut from a web of material and then sewn along the two edges by the machine according to the present invention. The machine according to the present invention is schematically shown in Figures 3 and 4.
The machine includes folding means 60 which comprise a pair of folding arms or paddles 10 and 11 which are attached to a central shaft 13 by radial arms 14 and are radially adjustable along the arms 14 to allow different widths of bag to be folded. The shaft 13 is rotatable about an axis 12 and the paddles 10,11 are arranged to be generally parallel to the axis 12. On rotation of the shaft 13 the paddles travel along a circular path. The web of fabric 66 is fed to the folding means in a direction perpendicular to axis 12 so that on rotation of shaft 13 the paddles serve to fold the material 15. The shaft 13 includes gripping means, preferably in the form of a row of pins 16 which serve to hold an end edge of the web 66 during the folding operation. Severing means 70 preferably in the form of heater wires 17 which extend along the length of the shaft 13 and are secured at each end thereto. Electricity is supplied to the wire 17 supplied via slip rings (not shown).
Fabric holding means 80 are provided which serve to hold the side edges 104 in a suitable condition for seaming after severance of the folded fabric from the web 66. The holding means 80 comprises fabric gripping means preferably in the form of a row of pins 20 attached to a support arm or plate 21 which is pivoted about axis 22 via arms 23 and bar 24. A fabric release plate 25 (figure 5) is hinged about axis 26 on bar 24 so that it can be moved to position 25(a) to eject the material from pins 20 after the seaming operation.
A bag ejection means 90 is preferably provided for ejecting a completed bag from the machine. The ejection means preferably comprises a continuously rotating wheel 30 which is rotated about axis 31, and made resiliant typically by making it up as a circular brush with stiff radial bristles. The brush 30 is located adjacent to the circular path of movement travelled by the paddles 10,11 so that when a paddles moves adjacent the brush the folded edge 103 comes into contact with the bristles and they eject the completed bag from the paddle.
Seaming along the side edge 104 and the end edge 105 is done by sewing machines 40 and 41 respectively. The machines are moved along rails 42, 43, typically supported and guided by grooved rollers 44. The sewing machines preferably incorporate conventional folding attachments (not shown) to form a folded over hem while sewing. As seen in Figure 3c, the holding means 80 moves to a seaming position whereby it has removed the edges 104 from shaft 13 and presented them to a position adjacent to the path of travel of the sewing machines.
The geometry between the pivot axis 22, distance of holding bar 24 from axis 22, distance between axis 22 and that of shaft 13, and the distance between folding arms 10,11 and shaft 13 is chosen so that for the maximum width of bag to be produced, the folded material is held in a tight manner between a folding arm and the holding bar 24 during the seaming operation. This is particularly advantageous for achieving satisfactory seaming along the end edge 105 by sewing machine 41.
If the arms 10, 11 are moved toward the shaft 13 for producing narrower bags, the geometry referred to above is changed resulting in a possible slackening of the folded material between a folding arm and holding bar 24. In order to accommodate for this change of geometry and thereby maintain a tightness in the folded material during seaming along edge 105 it is preferred to provide each arm 10,11 with an outwardly biased pivoted finger 10a (shown only in Figure 4a in broken lines) which is located adjacent to the terminal end of the arm 10,11 for internal engagement with the folded edge 103.
The operation of the machine is as follows:-
The end of the web of fabric 66 is held by pins 16 on shaft 13 and the shaft is rotated thereby causing paddle 10 (Figure 3d) to engage the web 66 and initiate the folding operation. The folding operation is shown as completed in Figure 3b, an intermediate position being shown in Figure 3a. After the paddle folding the fabric passes by the support arm 21, which is located outside the circular path of travel of the paddle, the arm 21 begins to move radially inwardly toward a fabric engaging position. This is illustrated in Figure 3a. After paddle 10 has moved to bring the lower fabric portion 67 into contact or close proximity of the shaft 13, the pins 20 on the arm 21 initially engages the lower fabric 67 and causes a tranverse portion to contact and be engaged by a second row of pins 16 and also cause the fabric to be cut by contact with the hot wire 17. At this stage both side edges 104 have been formed and the end of the web of fabric 66 is secured on pins 16 for the next folding operation by paddle 11. Continued upward movement of the support arm 21 causes the pins 20 to engage the upper fabric 68 and remove it from pins 16 and both fabric side edges 104 are then moved upward in a held condition to a seaming position. This is shown in Figure 3c.
Sewing machines 40 and 41 are then traversed along their rails to seam edges 104 and 105 together (Figure 4c). The arm 21 is then raised further to cause a lever (not shown) to hit a stop and cause the plate 25(a) to pivot and thereby eject the fabric from the pins 20 (Figures 3 and 4d). At the same time paddle 10 moves along its circular path to put the folded edge 103 of the bag into the path of the ejector wheel 30 which throws the finished bag from the paddle and onto a heap at the side of the machine. The sewing machines are then returned to their original positions (Figure 4a). The cycle of operations is then repeated, this time with paddle 11 folding the next piece of material.
The shaft 13 is intermittently rotated typically by a servomotor. The bar 23 is oscillated typically by a cam deriving motion from the shaft 13. The sewing machines are traversed typically by servomotors, acting through racks and pinions, and the sewing machines driven by separate motors or via clutches from the traverse motors.

Claims

A bag forming machine including folding means for folding a web of fabric to form two superimposed layers of fabric joined along one side by a fold, holding means for holding the folded fabric along the side edge opposite the fold, severing means for severing the folded fabric from the web of fabric material, and sewing means for seaming the folded fabric along the edge opposite said fold and along one end edge extending between the fold and said side edge.
A machine according to claim 1, wherein the folding means comprises at least one folding arm extending transversely of the path of feed of said web material, the folding arm being mounted on a shaft and being arranged parallel thereto, the shaft including gripping means for gripping an end edge of the web fabric such that rotation of the shaft causes the folding arm to move about a circular path to engage the web fabric and then on continued movement along the circular path of travel to simultaneously fold and draw the web fabric to form two superimposed layers of fabric and also bring a transverse portion of the fabric into contact with the gripping means on the shaft in preparation for severance.
A machine according to claim 2, wherein at least one pair of diammetrically opposed folding arms are provided.
A machine according to claim 2 or 3, wherein each folding arm is arranged to move the folded edge into engagement with ejection means for ejecting the completed bag from the machine.
A machine according to claim 2, 3 or 4, wherein the gripping means comprises at least one row of pins.
A machine according to any of claims 2 to 5, wherein the holding means comprises a support arm located parallel to the shaft axis and arranged to move from a remote location whereat it lies outside said circular path of travel to a fabric engaging position adjacent to said shaft, the support arm including fabric gripping means, preferably in the form of pins, for gripping the fabric during severance and preferably seaming.
A machine according to any of claims 2 to 6, wherein the severance means comprises an electric heater which extends along the shaft to engage said transverse fabric portion.
A machine according to claim 7, wherein the electric heater comprises a heater wire.
A machine according to claim 7 or 8, wherein the holding means is arranged so that during its movement from the fabric engaging position to the seaming position, it moves the fabric into contact with the heater wire and also the gripping means on the shaft.
A machine according to any of claims 2 to 9, wherein the seaming means comprises two sewing machines, one sewing machine being arranged to travel in the same direction and the other sewing machine being arranged to travel in a transverse direction to said shaft for seaming the end edge.
A process for forming a bag from a continuous web of material, the process including the steps of folding the web of fabric along a fold extending transversely relative to the longitudinal direction of the web, so as to form two superimposed layers of fabric joined along one side by said fold, holding the folded fabric along the side opposite to the fold, severing the folded fabric from the web and seaming the folded fabric along the edge opposite said fold and along the edge opposite said fold and along one end edge extending between the fold and said side edge.