FEED MEANS IN A STAPLE CASSETTE INTENDED FOR A STAPLER

Technical field The present invention relates to a feed means forming part of a staple cassette, which staple cassette is intended to be fitted in a stapler and houses elongate staple blanks which are connected together, long side to long side, to form an elongate staple strip which is fed forwards by engagement means which are disposed on the feed means and which in a feed movement engage with the staple strip on one flat side of the staple strip, said feed movement being effected by feed-forwards means forming part of the stapler.

State of the art There are previously known feed means of the kind indicated above. One such is referred to in the applicant's own patent SE 523 848. However, those previously known feed means have the disadvantage of only extending along one of the flat sides of the staple strip, with the result that the opposite flat side either completely lacks support or bears laterally on constituent parts of the staple cassette. Irrespective of whether the opposite flat side lacks support or bears against the cassette, it has been found that such arrangements have the disadvantage that when the staple blanks are fed by the engagement means in the feed movement they can spring away from the engagement means, with the result that the engagement means lose engagement, thereby causing the feeding forwards of the staple blanks to cease. This leads to the stapler effecting a so-called idle stroke, i.e. executing a stapling movement without any staple being driven into the sheaf of papers being stapled, or, in the worst case, to the stapler completely ceasing to operate when no feeding forwards of the staple blanks takes place.

Problem

There is thus a need for a feed means which forms part of a staple cassette and is so arranged that its engagement means do not lose engagement when feeding forwards of the staple blanks takes place.

Solution

The present invention overcomes the disadvantages indicated above by using a feed means of the kind indicated in the introduction which is characterised in that it comprises elements which prevent the staple blanks from springing away from the engagement means.

The present invention is further characterised in that the elements take the form of parts which are integrated with the feed means and abut closely against the second flat side of the staple strip.

The present invention is yet further characterised in that the elements abut against said second flat side in the region opposite to the region of engagement of the engagement means.

In addition, the present invention is further characterised in that said parts have in the longitudinal direction of the path of the staple strip a longitudinal extent which is at least twice the width of the staple blanks.

Brief description of the drawings The invention is described below with reference to the attached drawings, which depict a preferred embodiment and in which:

Fig. 1 is a schematic view of a stapler which accommodates a staple cassette with a feed means according to the invention; Fig. 2 is a perspective view of a staple cassette;

Fig. 3 is a staple cassette as seen from in front;

Fig. 4 is a view of a staple cassette in which parts essential to the invention have been exploded;

Fig. 5 is a staple roll provided with a feed means according to the invention; Fig. 6 is a detail view of the feed means and an essential detail of the invention;

Fig. 7 depicts the feed means and parts of a staple strip path as seen from in front;

Fig. 8 is a view corresponding to Figure 7 as seen from below; Fig. 9 is a view corresponding to Figure 7 as seen from above;

Fig. 10 is a view corresponding to Figure 6 in which the engagement means have a different location.

Preferred embodiment Fig. 1 depicts schematically a stapler 1 comprising a base part 2 and a stapling head 3 which is connected to the base part 2 by a pivot pin 4. The stapling head 3 accommodates a staple cassette 5 which comprises a container 6 and a drive arrangement 7. The container accommodates a staple roll 8. The drive arrangement and the staple head are driven in a reciprocating movement, represented by the double arrow P, by drive arms 9 which are driven by a drive link 10 connected to a drive motor 11. An anvil 12 on which the workpiece 13 is placed for stapling is disposed on the base part 2. The diagram also indicates schematically a feed-forwards means 14 which in a feed movement feeds the staple roll forwards.

Figs. 2-6 depict the container 6 which accommodates the staple roll 8 comprising elongate staple blanks 15 which are connected together, long side to long side, by an adhesive tape 16 to form a staple strip which in the application here concerned is wound to the shape of a roll. These drawings also depict the feed means 17 extending transversely relative to the staple strip's longitudinal direction L along the whole width B of the staple strip and along the first flat side 18 of the staple strip. The feed means comprises a base part 19 extending along the staple strip's whole width and a first bent-over flange 20 and a second bent-over flange 21. The feed means further comprises first and second protrusions 22 and 23 respectively which each have a guide surface 24 and 25 respectively. These drawings also depict a forming plate 26 comprising a forming block 27 across which the staple blanks are bent to staple shape. However, as this bending is of no significance for the invention here concerned, no further description of it is given herein. The forming plate comprises a central plateau 28 which has a first side edge 29 and a second side edge 30. The forming plate further comprises snap means 31 and 32 respectively. The feed means is applied to the forming plate in such a way that the guide surfaces 24 and 25 respectively come into sliding contact with the side edges 29 and 30 respectively, followed by the forming plate being fitted to the container 6 by the snap means 31 and 32 respectively being snapped to fillets 33,34

disposed on the container 6. When these parts are applied to the container as depicted in Figs. 2 and 3, the feed means can with the feed-forwards means 14 in a conventional manner be moved to and from in the longitudinal direction of the staple strip, a movement which is not depicted in the drawings but will be obvious to one skilled in the art. As may be seen clearly in Figs. 2 and 5, the base part 19 of the feed means extends on the first flat side 18 of the staple strip, and the bent-over flanges 20,21 on the opposite second flat side 35 of the staple strip which therefore extend through the aperture O between the base part and the flanges, as may most clearly be seen in Fig. 7.

Figs. 6-9 show the feed means in the base part 19 comprising engagement means 36 and 37 respectively which engage with the staple strip's first flat side 18, and elements 38 and 39 respectively which are integrated with the flanges, abut closely against the staple strip's other flat side 35 and prevent the possibility of the staple strip rising in the direction K away from engagement with the engagement means. As illustrated, the respective elements each take the form of a platform-like tab with a width b which in the longitudinal direction of the staple strip is at least the width of two staple blanks. The location of the elements 38,39 relative to the engagement means 36,37 may be seen clearly in Fig. 8, which shows them situated in regions which are opposite one another. This positioning is nevertheless not necessary for the invention to function, as it is also possible for them to be located in such a way as to be displaced relative to one another. Fig. 10 shows how the engagement means can be integrated with the flanges 20,21.

When feeding forwards of the staple strip takes place, the engagement means 36,37 therefore engage in the staple strip and the feed means is moved forwards by the feed-forwards means, thereby feeding the staple strip forwards. The elements 38,39 abutting closely against the staple strip's second flat side 35 prevent the engagement means from losing their engagement. When the feed-forwards means moves the feed means in the opposite direction, the engagement means, as a result of their slope most clearly visible in Figs. 6-8, will easily, in a manner known to one skilled in

the art, move along the staple strip without the latter being simultaneously fed in a rearward direction.