WO2008136726A1

WO2008136726A1 - Stapler

Info

Publication number: WO2008136726A1
Application number: PCT/SE2008/000294
Authority: WO
Inventors: Martin Elonsson; Peter Johansson; Bengt Ivarsson
Original assignee: Isaberg Rapid Ab
Priority date: 2007-05-03
Filing date: 2008-04-29
Publication date: 2008-11-13
Also published as: SE530057C2; SE0701055L

Abstract

Stapler (1) for using a U-shaped staple (8) which comprises a first leg (10) and a second leg (11) with an intermediate staple crown (12), to staple a workpiece (6) such as a sheaf of papers, which stapler comprises a base part (2) against which the workpiece is placed, and a stapling head (3) which is connected pivotably to the base part and in which a staple magazine (7) is situated. The staple magazine (7) accommodates staples, a driver (13) by which the staple is driven into the workpiece, and a flexible ramp surface (16) which supports the staple crown when the staple is driven into the workpiece and which is moved away by the staple crown when the staple is driven into the workpiece wherein the ramp surface (16) moves in parallel rearwards when acted upon by the driver.

Description

STAPLER

Technical field

The present invention relates to a stapler for using a U-shaped staple which comprises a first and a second leg and an intermediate staple crown, to staple a workpiece such as a sheaf of papers, which stapler comprises a base part against which the workpiece is placed, and a stapling head which is connected pivotably to the base part and in which a staple magazine is situated; which staple magazine accommodates U-shaped staples, a driver by which the staple is driven into the workpiece, and a flexible ramp surface which supports the staple crown and which is moved away by the staple crown when the staple is driven into the workpiece.

State of the art

Staplers of the kind indicated above are previously known and the arrangement of a ramp surface which supports the staple crown serves the purpose of ensuring that the staple crown does not collapse before the crown reaches the workpiece, which can easily happen when stapling into thick sheaves of papers or into paper for colour copying, these being situations in which great force is required for driving the staple into the workpiece. The disadvantage of such staplers, however, is that since the ramp surface is associated with a leaf spring arrangement, the slope of the ramp surface relative to the driving direction of the driver decreases depending on how far the driver has driven the staple into the workpiece, which means that the support for the staple crown decreases depending on how far the driver has driven the staple into the workpiece. The leaf spring arrangement also causes the force required for moving the ramp surface away to decrease the further the driver drives the staple into the workpiece, which likewise means that the supporting effect decreases depending on how far the driver has driven the staple into the workpiece. Moreover, it is not possible, in cases where it is desired to vary the supporting force, to organise the arrangement in such a way that the supporting force increases during part of the staple driving operation. Finally, manufacturing and assembling the leaf spring arrangement in such a way that different arrangements result in substantially the same supporting effect is very complicated and readily leads to the manufactured products varying in quality, which is considered very unsatisfactory.

Problems There is therefore a need to propose a stapler of the kind indicated in the introduction which has a ramp surface with a slope which during the staple driving operation does not decrease relative to the driving direction of the driver, and in which the force required for moving the ramp surface away does not decrease during the driving operation and the ramp surface can be so disposed that the support of the surface increases during part of the driving movement, which stapler is easy to manufacture and assemble in such a way that no great variation between different staplers occurs.

Solution The present invention provides a solution to the above problems with a stapler of the kind indicated in the introduction which is characterised in that the ramp surface moves in parallel rearwards when acted upon by the driver.

The invention is also characterised in that the ramp surface moves rearwards against the force exerted by an elastic means.

The invention is further characterised in that the elastic means exerts substantially the same force against the ramp surface throughout the movement of the ramp surface.

The invention is yet further characterised in that the force exerted by the elastic means on the ramp surface increases the further the ramp surface moves rearwards.

The invention is still further characterised in that the elastic means takes the form of a coil spring.

The invention is also further characterised in that the ramp surface has a concave curvature. Finally, the present invention is characterised in that the ramp surface is situated on a slide block which is supported for sliding in the magazine and which is acted upon by an elastic means which endeavours to move the block forwards.

Brief description of the drawings

A preferred embodiment example is depicted in the attached drawings, in which:

Fig. 1 is a schematic view depicting a stapler provided with the present invention;

Fig. 2 is a view depicting in detail in an initial position the parts which are essential to the invention;

Fig. 3 is a view corresponding to Fig. 2 in which the parts are in an intermediate position;

Fig. 4 is a view corresponding to Figs. 2 and 3 in which the parts are in a final position;

Fig. 5 is a view in which the items essential to the invention are depicted from in front in a position corresponding to Fig. 2;

Fig. 6 is a view corresponding to Fig. 5 in a state corresponding to Fig. 3;

Fig. 7 is a view corresponding to Fig. 5 in a state corresponding to Fig. 4;

Fig. 8 is a view illustrating the angular relationship between two parts which are essential to the invention;

Fig. 9 is a view depicting an alternative embodiment of a part which is essential to the invention.

Preferred embodiment

Fig. 1 depicts a schematic view of a stapler 1 equipped with the present invention. The stapler comprises a base part 2 to which a stapling head 3 is connected pivotably by a pivot pin 4 in such a way that the stapling head can be moved towards and away from the base part in the direction indicated by the double arrow P. An anvil 5 on which the workpiece 6 is placed for stapling is disposed on the base part. The figure also depicts schematically a magazine 7 which accommodates staples 8 in the form of a staple stack 9, which staples each have a first leg 10 and a second leg 1 1 with an intermediate crown 12 (see Fig. 7). Fig. 1 also depicts a driver 13 which is connected to the stapling head and by which a staple 8 is driven into the workpiece 6 in the direction indicated by the arrow D. A block 14 supported slidably in the magazine can slide on the magazine bottom 15 in a to and fro direction, represented by the double arrow L, which coincides with the longitudinal direction of the stapler. The block 14 has at its front edge a ramp surface 16 which is moved forwards by an elastic means 17 in the form of a coil spring and extends into the region in which the driver drives the staple 8 when the latter is driven into the workpiece. The block 14 is halted in its forward movement by walls 18, 19 disposed relative to the magazine which do not appear in Fig. 1 but are depicted in Figs. 5-7.

Figs. 2-4 illustrate the functioning of the ramp surface 16. In Fig. 2 the driver is at a position in which in the movement P it has driven the staple to a position in which the staple crown 12 has come into contact with the ramp surface 16. As may be seen in Fig. 8, the ramp surface 16 has an angle of inclination ά relative to the direction D.

In Fig. 3, the driver is at an intermediate position and the staple crown is supported by the ramp surface 16 which has moved rearwards against the force exerted by the coil spring, and in Fig. 4 the driver is at a bottom position in which it has driven the staple out of the magazine 8 and into the workpiece 6, which is not depicted in these diagrams. At this stage, the ramp surface has moved further rearwards and the fact that the ramp surface is disposed to the block 14 which moves rearwards in the longitudinal direction L of the magazine results in a parallel movement rearwards of the ramp surface, with the result that the angle ά does not change and the support from the ramp surface against the staple crown therefore remains substantially unchanged during the whole driving movement, assuming that the elastic means acts with substantially the same force throughout the rearward movement of the block 14.

As will be readily appreciated by one skilled in the art, the force exerted by the ramp surface against the staple crown can be varied by arranging the characteristics of the elastic means in such a way that it exerts a force which varies depending on how far the block 14 has moved rearwards. It is for example possible to vary the pitch of the coil spring along its length. It is also possible to vary the supporting force by varying the slope of the ramp surface relative to the driving direction, as illustrated in Fig. 9, which depicts an alternative form of the ramp surface. In the form depicted in Fig. 9, the ramp surface has a concave shape 20 which causes the supporting force to vary during the driving movement, and adapting the shape according to how thick the workpiece for stapling may be it is possible to obtain a force adapted to the thickness of the workpiece. Making the upper portion of the surface concave results in the supporting force at the lower concave portion being greater than at the upper concave portion and also relative to the region situated below the concave shape. Since the need for supporting force is greatest and increases until the tips of the staple legs penetrate through the workpiece, it has been found that such an effect is achieved specifically by a concave shape of the upper portion of the ramp surface. As one skilled in the art will readily appreciate, it is also possible to accomplish this effect by adjusting the opposing force of the elastic means by, for example, varying the pitch of the coil spring.

Claims

L A stapler (1) for using a U-shaped staple (8) which comprises a first (10) and a second leg (11) with an intermediate staple crown (12), to staple a workpiece (6) such as a sheaf of papers, which stapler comprises a base part (2) against which the workpiece is placed, and a stapling head (3) which is connected pivotably to the base part and in which a staple magazine (7) is situated; which staple magazine (7) accommodates staples, a driver (13) by which the staple is driven into the workpiece, and a flexible ramp surface (16) which supports the staple crown when the staple is driven into the workpiece and which is moved away by the staple crown when the staple is driven into the workpiece, CHARACTERISED in that the ramp surface (16) moves in parallel rearwards when acted upon by the driver.

2. A stapler (1) according to the above claim, CHARACTERISED in that the ramp surface (16) moves rearwards against the force exerted by an elastic means (17).

3. A stapler (1) according to claim 2, CHARACTERISED in that the elastic means exerts substantially the same force against the ramp surface throughout the movement of the ramp surface.

4. A stapler according to claim 2, CHARACTERISED in that the force exerted by the elastic means against the ramp surface increases the further the ramp surface moves rearwards.

5. A stapler according to claim 3 or 4, CHARACTERISED in that the elastic means takes the form of a coil spring (17).

6. A stapler according to any one of the above claims, CHARACTERISED in that the ramp surface has a concave shape (20).

7. A stapler according to any one of the above claims, CHARACTERISED in that the ramp surface (16) is situated on a slide block (14) which is supported slidably in the magazine (7) and acted upon by an elastic means which endeavours to move the block forwards.