Improvements relating to sheet feeding apparatus

Abstract

 Apparatus for feeding sheet material, e.g. in the form of plastics film to an operating machine in the form of a bag making machine, comprises a support device (6) comprising a support (8) on which a bulk supply (10) of sheet plastics film, conveniently in the form of a drum, may be mounted. Sheet material (12) is drawn from the drum over a sensing roller (14) through a securing device (16) thence around a pair of drive rollers (22) of a feeding means, to a take-up device (24). Simultaneously a sheet 42 from a stationary roller (38) extends in the securing device in face-to-face contact with the sheet (12)
   As the trailing edge of the sheet (12) comes off the drum (10), it passes the sensing roller (14) which thereby detects emptying of the drum (10), and causes rotation of the drive roller (22) momentarily to be terminated, whilst a welding device (16) secures the trailing end portion of the sheet (12) to the leading end of the second sheet. Feeding is then re-commenced, and if desired the support device (6) may be rotated through 180^o, to positionally interchange the drums (10 and 38), to enable the empty drum (10) to be replaced by a fresh drum, and sheet drawn therebetween and located in the securing device (16), to be secured to the sheets (42) when the sheet (42) empties.

Description

[0001] This invention is concerned with improvements relating to the feeding of sheet material, particularly from bulk supplies of sheet material, to an operating machine to carry out an operating (e.g. manufacturing) process on the sheet material.

[0002] Difficulty is encountered in this field, particularly where the operating machinery is designed to operate at high feed speed. For example, in the manufacture of plastic bags, the operating machine, adapted to produce bags from a supply of sheet plastics material, may operate at speed of 80 metres per minute or more. Whilst a storage or take-up device may be interposed between the supply of sheet material and the operating machine, it is usually necessary to terminate operations of the machine whilst the supply, conveniently in the form of drums of the sheet material, is changed.

[0003] According to this invention there is provided apparatus for feeding sheet material to an operating machine, the apparatus comprising a support for a bulk supply of the material, and means to feed sheet material from the bulk supply towards the operating machine, wherein the apparatus comprises a second support for a bulk supply of the material, and a securing device adapted to secure sheet material from the bulk supply on the second support to sheet material from the bulk supply on the first said support.

[0004] In this manner as the sheet material on the bulk supply on the first support ends, by securing the sheet material on the bulk supply of the second support thereto, a continuance of feeding of sheet material through the apparatus, and through the operating machine may be obtained.

[0005] Preferably the apparatus comprises means to constrain the material for movement along a pathway between the bulk supply and the feeding means, the securing device being located adjacent to the pathway.

[0006] If necessary operation of the feeding means may be briefly interupted whilst the two sheets are secured together but obviating the need to interrupt operation of the feeding means whilst a fresh bulk supply is mounted on the apparatus, the interuption to sheet feeding may be sufficiently short as to allow the operating machine to continue production without interuption.

[0007] Most conveniently the supports are adapted to support bulk supplies in the form of drums or reels of the sheet material.

[0008] Conveniently the sheet material is constrained for movement along said pathway by rollers, over which the material passes, conveniently being located between the bulk supply and the feeding means.

[0009] The securing device may be adapted to secure the material, conveniently in face-to-face relationship, such as by a welding process (e.g. heat or ultrasonic welding), particularly where the sheet material is plastics filmed.

[0010] Alternatively, and particularly where the sheet material is paper, alternative forms of securement may be utilised, such as by the use of a quick cure adhesive, or alternatively a mechanical securement may be utilised.

[0011] Preferably the supports are provided by a support device on which two bulk supplies may be mounted. Conveniently the support device is movable, conveniently by rotating to 180^o to enable the two supports to be positionally changed.

[0012] Advantageously means is provided to detect termination of a of one bulk supply (such as by the sensing of the passage of a trailing edge of the sheet material from the bulk supply) and which may be operative initially momentarily to interupt operation of the feeding means whilst the securing device is activated, and advantageously subsequently to move the support device so that the two bulk supplies are positionally interchanged, enabling the empty bulk supply conveniently to to be replaced by a fresh bulk supply, whilst sheet material continues to be drawn from the second bulk supply.

[0013] The invention is particularly useful where the apparatus comprises a take-up device, to provide between the feeding means and the machine a store of sheet material.

[0014] There will now be given a detailed description, to be read with reference to the accompanying drawing, of an apparatus which has been selected for the purposes of illustrating the invention by way of example.

[0015] The accompanying drawing is a schematic side elevation of the preferred embodiment.

[0016] The apparatus which is the preferred of this invention is particularly for use in the feeding of sheet material in the form of plastics film to an operating machine in the form of a bag-making machine. The apparatus comprises a support device 6 comprising a support 8 on which a bulk supply 10 of sheet plastics film, conveniently in the form of a drum or roll, may be mounted. Sheet material 12 is drawn from the drum 10 over a sensing roller 14 through a welding device 16, the material being constrained to follow a pathway through the welding device 16 by a pair of spaced rollers 18, 20. From the roller 20 the sheet is fed around a pair of drive rollers 22 of a feeding means, and around further rollers to a storage or take-up device 24. The storage device 24 comprises a fixed upper frame 26, supporting in spaced relationship a plurality fixed horizontal rollers 28, and a hanging bar 30 supporting a plurality of hanging rollers 32. The sheet material is threaded around the rollers 28 and 32, and exits from the device 24 at the position X, from which it is fed to the operating machine. As the machine draws sheet material from the device 24 at a rate greater than that at which it is fed by the feeding means 22, the hanging bar 30 rises: where the operation of the feeding means 22 exceeds the rate of which the operating machine utilises sheet material, the hanging bar 32 falls, until at a lower most position it activates a microswitch (not shown) temporarily to terminate operation of the rollers 22.

[0017] The support device 6 comprises a second support 36 for a second drawn of sheet plastics film, from which the sheet material 42 is drawn over a sensing roller 14, over the roller 18 and through the welding apparatus 16.

[0018] During utilisation of the sheet material from the roll 10, frictional forces with the sheet 42 retain the material from the drum 38 in tension, means if desired being provided to constrain the drum 38 against rotation. As the trailing edge of the sheet 12 come off the drum 10, it passes the sensing means conventionally in the form of a sensing roller 14 which thereby detects emptying of the drum 10, and causes rotation of the drive rollers 22 momentarily to be terminated, whilst the welding device 16 secures the trailing end portion of the sheet 12 to the leading end portion of the sheet 42. Typically, this operation takes about 5 seconds, during which time the requirement of the operating machine for sheet plastics material is obtained from the storage device 24. On completion of the welding operation rotation of the drive rollers 22 is commenced, drawing sheet material from the drum 38.

[0019] At this stage, or if desired immediately prior to this stage, the support device 6 as a whole is rotated in the direction of the arrow Y through 180^o, to enable the drums 10 and 38 to be positionally interchanged. This enables the empty drum 10 readily to be removed from the support 8, and be replaced by a fresh drum, and the leading end portion of the sheet material thereon to be fed over the roller 18 and into the welding apparatus 16, in which position the drum and sheet material thereof remain until emptying of the drum 38, detected by a sensing roller 40 similar to the sensing roller 14.

[0020] By the use of the apparatus above described, it has been found that the rate at which the operated machine is interupted may be greatly reduced, allowing for the more efficient operation of the machine.

[0021] It is to be appreciated that whilst the apparatus above described has been designed primarily for use in the production of articles (such as bags) from sheet plastics material, the invention may be utilised in other fields where similarly or analogous problems arise.

[0022] The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. Apparatus for feeding sheet material to an operating machine, the apparatus comprising a support (8) for a bulk supply (10) of the material, and means (22) to feed sheet material from the bulk supply towards the operating machine, wherein the apparatus comprises a second support (36) for a bulk supply (38) of the material, and a securing device (16) adapted to secure sheet material from the bulk supply on the second support to sheet material from the bulk supply on the first support.

2. Apparatus according to Claim 1 comprising means (18, 20) to constrain the material for movement along a pathway between the bulk supply and the feeding means, the securing device (16) being located adjacent to the pathway.

3. Apparatus according to one of Claims 1 and 2 wherein the securing device (16) is adapted to secure the material in face-to-face relationship.

4. Apparatus according to any one of the preceding claims wherein the securing device is adapted to secure the material by a welding process, adhesive or by mechnical securement.

5. Apparatus according to any one of the preceding claims wherein the supports (8, 36) are provided by a support device (6) on which two bulk supplies (19, 38) may be mounted, the support device (6) being rotatable through 180^o to enable the two bulk supplies to be positionally interchanged.

6. Apparatus according to any one of the preceding claims comprising means (14, 40) to detect termination of a bulk supply, said means being operative to sense the passage of a trailing edge of the sheet material from the bulk supply.

7. Apparatus according to Claim 6 wherein the sensing means is operative momentarily to interupt operation of the feeding means.

8. Apparatus according to Claim 6 and 7 wherein operation of the sensing means is operative to cause the two bulk supplies to be positionally interchanged.

9. Apparatus according to any one of the preceding claims wherein, in use, material from one bulk store is drawn therefrom through the securing device, and a leading edge portion of sheet material from the second bulk supply is located in the securing device, the two sheets being in face to face contract, frictional contract therebetween retaining the sheet material in the second bulk supply tension.

10. Apparatus according to Claim 9 wherein sheet material from the first said bulk store (10) is drawn through the securing device (16) beneath the sheet material from the second bulk store (38).

11. Apparatus according to any one of the preceding claims comprising a take-up device (24) between the feeding means (22)and the operating machine (X).

Drawing