GB2191468A - Pneumatic valve mechanism for removing sheets from a stack - Google Patents

Abstract

A pneumatic valve mechanism, especially for removing sheets of paper from a stack, comprises a first manifold (12) having suction mouthpieces (16) arranged jointly and simultaneously to contact a sheet to be grasped, a second manifold (14) connected to a source of suction (28) and a plurality of bellows (10) which are biased to their extended condition and connect the manifolds. Each bellows (10) contains a valve body (22) with a seal (24) which can contact a spigot (18) on the first manifold. The seals are effective when the bellows are fully retracted, following closure of the mouthpieces (16), to seal the first manifold (12) from the source of suction. The first manifold (12) is vented to atmosphere through apertures (17) in the retracted position of the bellows, to release the sheet, but without breaking the seals, whereby the bellows are maintained in the retracted position. It is only when the seals are broken by a positive actuation that the bellows (10), first manifold (12) and mouthpiece (16) are permitted again to move towards their extended position. <IMAGE>

Description

SPECIFICATION Valve mechanism This invention relates to valve mechanisms, and is particularly concerned with a pneumatic valve mechanism which incorporates a bellows or like mechanism and which can be used for example for the controlled movement of sheets of paper, card or like material.

Various types of suction mechanism are known for use in moving sheets of paper or like material. More particularly, valved suction mechanisms are known, but these generally tend to be complex either in their construction, their manner of operation or their control.

Our co-pending British patent application 8521942 (publication number GB 2164019A) describes a pneumatic valve mechanism which is extremely simple in its construction and manner of operation, yet by means of which one can achieve various desirable results in terms of the way in which items, such as sheets of material, e.g. paper, are controllably moved.

The present invention is concerned with a multiple valve unit where the valves act in concert and function together to initiate movement of items to be displaced.

In accordance with the present invention there is with the invention will now be described by way of example, and with reference to the accompanying drawings.

In the drawings: Fig. 1 is a schematic illustration, partly in section, showing a number of pneumatic valve mechanisms coupled to form a multiple unit; Fig. 2 shows the composite unit of Fig. 1, but with the bellows retracted; Figs. 3a, 3b, 3c and 3d show the operational sequence of a bellows unit taking a sheet of material, such as paper, from a stack.

As shown in Figs. 1 and 2, the pneumatic valve mechanism, here applied to paper handling, of the present invention comprises a plurality of bellows 10 (here three bellows are shown) extending between and connected to a first manifold 12 and a second manifold 14.

The bellows 10 are shown equally spaced in this embodiment. The bellows have a natural or added bias to cause them normally to adopt an extended position. The first manifold 12 is fitted with a number of suction cups 16, each of which constitutes a mouthpiece and each of which has a hollow centre in alignment with a corresponding hole through the wall of the manifold 12. In the illustrated embodiment, five suction cups 16 are shown, spaced at intervals along the length of the suction cup manifold 12. These suction cups are arranged jointly and simultaneously to contact the edge zone of a sheet of paper or like material for the controlled movement thereof.

The number and relative positioning of the suction cups 16 may be varied, depending upon the particular machine, the type of paper, and the controlled movement of the sheet whichis required. The suction cup manifold 12 is also provided with one or more holes 17 which serve as venting holes to atmosphere, for a purpose to be described hereinafter.

As shown most clearly in Figs. 3a to 3d, the individual suction cups 16 are "angled" so that they make contact progressively with the stack of paper and so that the peeling action initiated by the valve mechanism operates smoothly and efficiently.

The end of each bellows 10 adjacent to the suction cup manifold 12 is fixed to an annular spigot 18 which is fixed to or is integral with the suction cup manifold 12. A hole 20 is provided in the suction cup manifold 12 centrally of each spigot 18 to provide an air passage from the manifold towards the interior of the bellows.

Fixed to or integral with the second manifold 14, for each bellows 10, there is provided a valve body 22 which extends coaxially within the bellows. A hole 23 is provided in the second manifold 14 in association with each valve body 22 to create a passageway between the interior of the manifold 14 and the interior of the valve body 22. Each valve body 22 comprises a hollow tubular member which is closed at its end within the bellows and which carries a seal member 24 of suitable material on its outer axial end face. The side wall of the valve body 22 is provided with circumferentially spaced holes 26 which provide a passageway between the interior of the valve body and the interior of the bellows outside the valve body.

The manifold 14 is provided with a connecting pipe 28 to a pump or other source of vacuum. The vacuum source referred to herein, preferably a pump or like device, creates a reduced air pressure or suction air flow, not of course a true vacuum.

Referring now to Figs. 3a to 3d, in conjunction with Figs. 1 and 2, the manner of operation of the unit will now be described. Fig.

3a shows a stack 30 of sheets of paper or like material from which the top sheet of the stack is to be removed. In the position shown in Fig. 3a, the vacuum source is operative and there is an air flow, as shown by the arrows, in through the suction cups, through the suction cup manifold, through the respective bellows, and through the vacuum manifold. In this state the bellows 10 are in their normal extended state and the suction cups are in their "seeking" position. One can use the valve mechanism in two alternative ways.

Firstly, if the top sheet of the stack is within the range of extension of the bellows, then the suction cups will strike this sheet without moving either the stack or the whole bellows housing. Alternatively, one can either move the stack 30 of sheets towards the bellows unit or move the bellows unit towards the stack of sheets or move both towards each other. Whichever alternative is chosen, a stage will be reached, as shown in Fig. 3b, where the suction cups 16 make contact with the top sheet of the stack 30. When this happens the openness of the suction cups to atmosphere is stopped and reduced pressure is created within the individual bellows 10.

The vent holes 17 are sized so as not to prevent retraction of the bellows when the suction cups are closed off by the paper sheet. By virtue of the angled suction cups 16, as shown in Fig. 3c, the top sheet of the stack 30 is peeled away, rather than simply pulled away. This peeling action continues as the vacuum source continues to function and as the respective bellows 10 retract towards the position shown in Fig. 3d and Fig. 2. In this position the spigots 18 attached to the suction cup manifold 12 make a sealing contact with the seal member 24 on the valve body 22, thereby breaking the communication path to the vacuum source. In this position the sheet of paper is released from the suction cups 16, the suction manifold being vented to atmosphere by the hole or holes 17.However, the suction manifold 12 is held back in the retracted position, by the suction effect, even after release of the paper, until the seals are broken. In order to break the seal between the spigots 18 and valve bodies 22 it is simply necessary to exert a pressure against the suction cup manifold 12 in a direction to push it away from the vacuum manifold 14, as indicated by the arrow 32 in Fig.

2. This can be accomplished by any suitable means, mechanical, electromechanical, or electromagnetic for example.

Although the valve mechanism of the present invention is particularly appropriate for the handling and movement of sheets of paper, card and like material, it also finds application in the handling of other items, essentially in any situation where one wishes to pick up and move an item. The food industry is one example, where carton lids for example could be moved in this way. Non-paper items can also be handled, for example plastics or metal lids for paint cans. Robotics too is an area in which the handling capabiiities of the valve mechanism of the present invention fulfil a need.

Claims (9)

1. A pneumatic valve mechanism comprising a first manifold provided with a plurality of suction mouthpieces which are spaced along its length and which are arranged jointly and simultaneously to contact an item to be grasped; a second manifold arranged to be connected to a source of suction; a plurality of extensible and retractable sleeves connected between said first and second manifolds; passage means to connect the interior of each sleeve to said second manifold such that when the sleeves are not fully retracted suction is created in said first manifold and at the mouthpieces; a valve body within each sleeve; means to create seals between the first manifold, or extensions thereof, and the respective valve bodies, which seals are effective when the sleeves are fully retracted, following closure of the suction mouthpieces, to seal the first manifold from the source of suction; venting means permitting air to enter the first manifold in the retracted position of the sleeves but without breaking the seals, whereby the sleeves and first manifold are maintained in the retracted position; and actuating means arranged upon operation to break the seals and thereby permit the sleeves and first manifold to return towards their extended position.

2. A valve mechanism as claimed in claim 1, in which each sleeve is a bellows.

3. A valve mechanism as claimed in claim 1 or 2, in which said first and second manifolds comprise generally parallel, elongate, hollow tubes.

4. A valve mechanism as claimed in any preceding claim, in which the sleeves are spaced at regular intervals along the manifolds and the suction mouthpieces are spaced at irregular intervals along said first manifold.

5. A valve mechanism as claimed in any preceding claim, in which the first manifold is provided with a plurality of spigots around respective holes in the manifold, each spigot being arranged to make sealing contact with a respective valve body as the sleeves are retracted.

6. A valve mechanism as claimed in any preceding claim, in which the venting means comprises one or more holes in the first manifold.

7. A valve mechanism as claimed in any preceding claim, in which the actuating means is arranged to exert a force against the first manifold, the second manifold remaining stationary.

8. A valve mechanism as claimed in any preceding claim, in which each suction mouthpiece is set at an angle to the item which it is seeking to grasp whereby the mouthpiece makes gradual contact with said item.

9. A valve mechanism substantially as hereinbefore described with reference to the accompanying drawings.