GB2141685A

GB2141685A - Bag-forming machine

Info

Publication number: GB2141685A
Application number: GB08309934A
Authority: GB
Inventors: Frank John Rowell
Original assignee: ROPACK Ltd
Current assignee: ROPACK Ltd
Priority date: 1983-04-13
Filing date: 1983-04-13
Publication date: 1985-01-03
Also published as: GB8309934D0

Abstract

In a bag-forming machine, a flexible tube (12) is advanced and transversely sealed by bars (11). Spreaders (4) are used to engage opposite inner surfaces of the tube (12) and spread and flatten the tube (12) prior to sealing, thus avoiding puckers. The bag can be filled while the spreaders (4) are still within the bag. In order to avoid difficulties caused by friction between the tube (12) and the spreaders (4), and also to allow the bag to assume a more roundish shape for filling, the spreaders (4) are retractable and openable pneumatically, the stroke of the pneumatic ram being limited so that when open, the spreaders (4) assume a fixed, predetermined position. The retraction and opening of the spreaders (4) is cyclical, the spreaders (4) being retracted while the tube (12) is advanced and being open while the tube (12) is stationary. <IMAGE>

Description

SPECIFICATION Bag-forming machine In GB 2065599A, there is described an automatic or part-automatic bag-forming machine, which has spreaders for avoiding puckers or wrinkles in the tube prior to forming a transverse seam. There are also grippers which grip the sides of the tube and move aprart transversely. In this way, a liquid-tight container can be provided.

It has now been found better to use spreaders which can be retracted cyclically, and/or spreaders which have a fixed position when they are operative. The spreaders can be used with or without'the grippers.

The spreaders can open automatically to a fixed, pre-determined position, and can be retained in this position until the transverse seam has been formed, being retracted as soon as practicable after forming the transverse seam. By having a fixed position, the width is precisely determined in such a way that the tube will be perfectly flat. By retracting the spreaders, there is less friction when advancing the film to form the next bag or container, and also the bag or container can assume a more roundish shape for filling.

The fixed position of the spreaders can be adjustable, according to the container width or possibly factors such as the elasticity of the film.

Preferably, the spreaders are close above the means for forming the transverse seam and the grippers, if present, are close below such means.

The spreaders are preferably pressure-fluid actuated, pneumatic action being most preferred.

An embodiment of the invention is illustrated in the accompanying drawing. The machine can be a known bag-forming machine, for instance as in GB 2065599A. So as to be within the tube of film, there is a circularsection forming tube 1 which carries two slotted brackets 2 and a slide bracket 3.

Diametrically opposed spreaders 4 are pivoted to the brackets 2 and are connected by pivoted links 5 to a head 6. The head 6 is mounted on the end of a rod 7, guided by a guide sleeve 8 held by the bracket 3 and connected to a double-acting, adjustablestroke pneumatic ram 9. The ram 9 is mounted on the top-most plate 10 of the machine. It will be seen that retraction of the rod 7 retracts the spreaders 4, and extension of the rod 7 extends the spreaders 4 to a predetermined fixed position.

A standard arrangement can be used for forming a transverse seam, including a clamp bar 11. The top of the clamp bar 11 will be just below the retracted position of the spreaders 4. The side of the spread tube is indicated at 12.

1. A bag-making machine, comprising: means for feeding a flexible tube which will provide the wall of a bag; spreaders which will be positioned within the tube, for engaging opposite inner surfaces of the tube and spreading and flattening the tube, the spreaders assuming a fixed, predetermined position when operative, but being retractable; means for actuating the spreaders so that they are retracted as the feed means feeds the tube, and are then opened into said fixed position; and means adjacent the spreaders for forming a transverse seam across the tube, to close the tube.

2. A bag-making machine, for making containers out of flexible material, comprising: diametricaily-opposed spreaders; feed means for feeding a tube of flexible material over the spreaders so that the spreaders form the tube into a pucker-free shape of elongate cross-section; means for actuating the spreaders so that they are retracted as the feed means feeds the tube, and are then opened up into a fixed, predetermined position in which they spread and flatten the tu be; and sealing means downstream of the spreaders, for sealing the sides of the tube to each other along a transverse zone.

3. The machine of Claim 1 or Claim 2, wherein grippers are provided downstream of the seal-forming or ceiling means for gripping the outer surfaces of the edges of the flat tube and tensioning the tube transversely by relative transverse movement between the grippers.

4. The machine of any of the preceding Claims, wherein the spreaders are pneumatically actuated.

5. A bag-making machine, wherein the spreaders are substantially as herein described with reference to, and as shown in, the accompanying drawings.

6. A method of making a flexible liquid tight container in a bag-making machine, the method comprising: making a tube of flexible material; passing the tube over diametrically-opposite spreaders while the spreaders are retracted; when the tube is stationary, actuating the spreaders to open them into a fixed, predetermined position in which they engage opposite inner surfaces of the tube and spread and flatten the tube to form a pucker-free shape of elongate cross-section; and sealing the sides of the tube to each other along a transverse zone.

7. The method of Claim 6, wherein the spreaders are close upstream of the means for sealing the sides of the tube to each other, and grippers are provided downstream of the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Bag-forming machine In GB 2065599A, there is described an automatic or part-automatic bag-forming machine, which has spreaders for avoiding puckers or wrinkles in the tube prior to forming a transverse seam. There are also grippers which grip the sides of the tube and move aprart transversely. In this way, a liquid-tight container can be provided. It has now been found better to use spreaders which can be retracted cyclically, and/or spreaders which have a fixed position when they are operative. The spreaders can be used with or without'the grippers. The spreaders can open automatically to a fixed, pre-determined position, and can be retained in this position until the transverse seam has been formed, being retracted as soon as practicable after forming the transverse seam. By having a fixed position, the width is precisely determined in such a way that the tube will be perfectly flat. By retracting the spreaders, there is less friction when advancing the film to form the next bag or container, and also the bag or container can assume a more roundish shape for filling. The fixed position of the spreaders can be adjustable, according to the container width or possibly factors such as the elasticity of the film. Preferably, the spreaders are close above the means for forming the transverse seam and the grippers, if present, are close below such means. The spreaders are preferably pressure-fluid actuated, pneumatic action being most preferred. An embodiment of the invention is illustrated in the accompanying drawing. The machine can be a known bag-forming machine, for instance as in GB 2065599A. So as to be within the tube of film, there is a circularsection forming tube 1 which carries two slotted brackets 2 and a slide bracket 3. Diametrically opposed spreaders 4 are pivoted to the brackets 2 and are connected by pivoted links 5 to a head 6. The head 6 is mounted on the end of a rod 7, guided by a guide sleeve 8 held by the bracket 3 and connected to a double-acting, adjustablestroke pneumatic ram 9. The ram 9 is mounted on the top-most plate 10 of the machine. It will be seen that retraction of the rod 7 retracts the spreaders 4, and extension of the rod 7 extends the spreaders 4 to a predetermined fixed position. A standard arrangement can be used for forming a transverse seam, including a clamp bar 11. The top of the clamp bar 11 will be just below the retracted position of the spreaders 4. The side of the spread tube is indicated at 12. CLAIMS

7. The method of Claim 6, wherein the spreaders are close upstream of the means for sealing the sides of the tube to each other, and grippers are provided downstream of the sealing means, gripping the outer surfaces of the edges of the flat tube and tensioning the tube transversely by relative transverse movement between the grippers.

8. A method of making a flexible liquidtight container in a bag-making machine, substantially as herein described with reference to the accompanying drawings.