EP0543617A1

EP0543617A1 - A stapling machine

Info

Publication number: EP0543617A1
Application number: EP92310478A
Authority: EP
Inventors: Edward Mark Harris; Anthony White; Michael Burlington
Original assignee: Acco Rexel Group Services Ltd; Ofrex Group Holdings PLC
Current assignee: Acco Rexel Group Services Ltd
Priority date: 1991-11-19
Filing date: 1992-11-17
Publication date: 1993-05-26
Anticipated expiration: 2012-11-17
Also published as: DE69204967T2; DE69204967D1; EP0543617B1

Abstract

A stapling machine incorporates a spring to apply force to a staple pusher (20,47), which pushes staples in a staple magazine (44) towards a staple ejection slot (5,46). The spring comprises a spring strip (21,49) having one end thereof wound into a spiral coil (22,50), the spiral coil (22,50) being received within a cavity (3,52) which retains the coil (22,50) in a predetermined position, a portion of the spring extending from the spiral coil (22,50) to the staple pusher (20,47). The spring (21,49) applies a constant force to the staple pusher (20,47), facilitating ejection of the last few staples. The design facilitates easy assembly of the stapling machine.

Description

THE PRESENT INVENTION relates to a stapling machine and more particularly to a stapling machine adapted to staple together a plurality of sheets of paper.
A conventional stapling machine incorporates a magazine which holds a "strip" of staples. The staples are biassed, by a staple pusher, towards an ejection slot provided at one end of the magazine. An ejection blade is adapted to move through the ejection slot to dispense staples from the magazine. The two legs of the staple then pass, in use of the device, through a plurality of sheets of paper and are then clinched together by means of an anvil.
The strip of staples provided for a stapling machine of this type comprises a plurality of wire staples which are secured together by means of an adhesive. The staples are mounted within the staple magazine and are guided smoothly towards the ejection slot. Difficulties can, however, arise when only a few staples of the strip of staples remain. There is a tendency for the staples to then tilt as the end staple is ejected from the magazine. To overcome this problem it is often necessary to provide a "staple steady" which lies over the strip of staples.
This problem is actually increased in most stapling machines due to the fact that the element which pushes the staples along the staple magazine towards the ejection slot is spring biassed and, when the supply of staples is nearly exhausted, the staple pusher has almost reached its terminal position. Using a conventional spring, if the strength of the spring is selected so that the spring is exerting a significant force when the staple pusher has almost reached its terminal position (which force is sufficient to hold the staples as the last few staples are ejected from the magazine) when the pusher has been pulled back to allow a fresh strip of staples to be inserted into the magazine, the force exerted by the pusher is far too large.
Thus, the person designing the stapling machine is presented with a dilemma when selecting the strength of the spring associated with the staple pusher since if the spring is strong enough to provide the desired effect when the supply of staples is nearly exhausted, it is too strong when a fresh supply of staples is inserted into the magazine, but if the spring is of a sufficient strength to enable a new supply of staples to be inserted in the magazine it is too weak when the supply of staples is nearly exhausted.
The present invention seeks to overcome or obviate the disadvantages of the prior art.
According to this invention there is provided a stapling machine incorporating a magazine for a strip of staples, means adjacent one end of the magazine defining a staple ejection slot, an ejection blade adapted to eject a staple through the ejection slot, means to actuate the ejection blade, a staple pusher adapted to push staples along the magazine towards the ejection slot and spring means engaging the staple pusher to apply a force to the staple pusher, wherein the spring means comprise a spring strip having one end thereof wound into a spiral coil, there being a cavity to receive and retain said spiral coil in a predetermined position, a part of the spring extending from the spiral coil to the staple pusher.
Preferably the stapling machine incorporates a further element which engages the staple magazine, the cavity retaining said one spiral coil in a predetermined position being defined on the element which engages the staple magazine.
Conveniently the stapling machine incorporates a staple steadY which lies over the magazine, and the cavity is formed on a guide element that is mounted on the staple steady.
Advantageously a magazine carrier is provided and the staple magazine is slidably mounted on the said magazine carrier so that the staple magazine may move from an operative position to a protracted position.
Preferably a catch is provided to retain the magazine in the operative position, the arrangement being such that if the catch is released the spring means will cause the staple magazine to move to the protracted position.
The stapling machine of the invention may be in the form of a pliers-type stapling machine.
Preferably means are provided to indicate when the supply of staples within the magazine is about to be exhausted.
Conveniently said means comprise one or more indicia present on the spring strip and a window to permit the spring strip to be viewed, the said one or more indicia being so located that they become visible when the supply of staples is about to be exhausted.
In one embodiment of the invention the spring strip has two ends each wound into a respective spiral coil, each coil being maintained in a predetermined position, a respective portion of the spring extending from each respective coil to the staple pusher, the part of the spring strip engaging the pusher inter-connecting the ends of said two respective portions of the spring.
Preferably each spiral coil is received in a recess defined in a guide element, the guide element being received in a cavity formed on a guide element which guides the staple pusher.
In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which

FIGURE 1 is a vertical sectional view of a stapling machine in accordance with the invention,
FIGURE 2 is a view of the magazine-holder,
FIGURE 3 is a view of the constant tension spring,
FIGURE 4 is a top plan view illustrating the constant tension spring in position,
FIGURE 5 is an exploded view of a modified embodiment of the invention, and
FIGURE 6 is an exploded view, corresponding to Figure 5 of another modified embodiment of the invention.

Referring initially to Figure 1, a stapling machine comprises an integrally moulded magazine-carrier 1 (which is shown most clearly in Figure 2), comprising an elongate magazine holding arm 2 which defines, in its under-surface, a recess 3 adjacent the free end of the arm and an axially extending channel 4, which communicates with the recess 3. Adjacent the free end of the magazine holding arm 2 a slot 5 is defined which can receive a staple ejection blade and a toggle catch 6 is also defined on the free end of the arm 2. This catch comprises a forwardly extending flexible arm with a protrusion on its lower surface.
A flexible driver arm 7 is formed integrally with the staple magazine holding arm 2 and is joined thereto at a position remote from the recess 3. The driver arm 7 overlies the arm 2. An upwardly open recess 8 is provided adjacent the junction of the two arms adapted to receive a hollow peg 9 provided on a removable cover 10. The removable cover 10 has a further protrusion 11 provided at the front of the cover, on the inner surface of the cover, adapted to be received within a recess 12 formed at the free end of the staple magazine holding arm 2. This enables the cover 10 to be easily placed and retained in position during manufacture of the stapling machine, simply by engaging the peg 9 in the recess 8 as a friction fit, and then moving the cover so that the protrusion 11 snaps into the recess 12.
The integrally formed magazine carrier 1 also comprises a lug 13 which extends towards the rear of the stapling machine (i.e. towards the right as shown in Figures 1 and 2), this lug defining an aperture 14 which forms a pivot point for a further component, and also carrying a stop 15.
A staple magazine 16 is provided which is slidably mounted on the under-side of the staple magazine holding arm 2. The front part of the staple magazine 16 defines an enlarged head 17, which is engaged by the toggle catch 6 to retain the staple magazine in the operative position. If the toggle catch 6 is released by lifting the forward end of the flexible arm until the projection on the under-surface of the arm is disengaged from the head 17, the staple magazine may slide to a protracted position in which it extends from the stapler. This enables fresh staples to be introduced into the magazine.
The staple magazine defines a slot 18 adjacent its forward end which is co-aligned with a staple ejection blade 19, which is received within the guide slot 5. The upper end of the staple ejector blade 19 is engaged by the free end of the driver arm 7. A staple pusher element 20 is provided adapted to push staples along the magazine towards the ejection slot. The staple pusher is connected to one end of a strip 21 of spring steel, the other end of which is coiled into a spiral. The spring strip 21 and the spiral 22 are shown most clearly in Figure 3. The spiral portion of the spring is retained within the recess 3 which, as can be seen most clearly from Figure 4, is slightly off-set from the centre of the arm 2. The main part of the strip 21 passes along the axial channel 4 defined on the underside of the arm 2 and is then connected to the staple pusher 20.
It has been found that a spring of this type exerts a constant tension regardless of the length of spring strip 21 which is withdrawn from the spiral coil. The spiral coil is retained within the recess 3 and a constant biassing force is applied to the staple pusher 20 regardless of whether the staple pusher 20 is retained at a significant distance from the recess 3 by a large number of staples present in the magazine or whether the staple pusher 20 is located relatively close to the recess 3 when nearly all the staples in the magazine have been exhausted.
During assembly of the stapling machine the coiled part of the spring is slipped into the recess 23 formed in the under-surface of the arm 2. There is no need to mount the coiled part on a spindle or shaft which facilitates both manufacture and assembly.
As is illustrated schematically in Figure 1 numbers are printed or painted on part of the strip, these numbers being visible through a window 23 provided for the purpose in the side of the cover 10. These numbers, which are visible in use of the stapling machine, provide an indication as to the number of staples remaining in the magazine and are printed on that part of the strip which is exposed when the staples in the magazine are almost exhausted.
A pivot pin 24 passes through the aperture 14 provided in the lug 13 and engages a further component 25 which is of elongate form and which carries, at its forward end, an anvil 26 adapted to clinch inwardly the legs of a staple ejected from the staple ejection slot 18 by the staple ejection blade 19. Part of the component 25 engages the stop 15. A leaf spring 27 is provided having one end engaging the pivot pin 24 and the other end slidably mounted on the upper part of the component 25 adjacent the anvil 26. The leaf spring is arched upwardly and engages the undersurface of the staple magazine 16.
A further actuating lever 28 is provided which is pivotally connected by means of a pivot 29 to the component 25 carrying the anvil 26. The lever 28, however, has a portion 30 which engages the upper surface of the actuating arm 7.
In operation of the stapling machine as thus far described a person will grasp the stapling machine in one hand, with the palm of the hand embracing the top of the cover 10 in the region above the pivot pin 24, and with the fingers of the hand curled around the exposed part of the actuating element 28. When pressure is applied initially the component 25 carrying the anvil 26 pivots upwardly about the pivot point 24, compressing the leaf spring 27, and subsequently the component 28 pivots about the pivot point 29, causing the portion 30 thereof to move towards the left and downwardly as shown in Figure 1. Thus the actuator arm 7 becomes deflected downwardly, driving the staple ejector blade 19 downwardly to eject a staple through the staple ejection slot 18. The arms of the staple pass through sheets of paper which care to be stapled together, which are located between the staple ejection slot 18 and the anvil 26. The arms of the staple are then clinched by the anvil to hold the sheets of paper together.
When a staple has been ejected the staple pusher 20 will move towards the left (as illustrated) under the constant tension applied by the constant tension spring 22. When all the staples have been exhausted (or at some earlier moment) a toggle catch 6 may be released and the effect of the spring 21 is to cause the magazine to slide to a position in which it protrudes from the cover 10. The staple magazine may then be slid manually to a fully forward position, and a fresh supply of staples may be inserted into the magazine. The magazine may then be pushed back into the stapling machine, causing the pusher 20 to be moved to a right-hand position as illustrated in Figure 1. The toggle catch 6 will again engage the head 17 provided at the forward end of the magazine to retain the magazine in position.
Thus the present invention provides the advantage that a constant tension spring is used to bias the staples towards the ejection slot, so that the biassing effect remains substantially constant regardless of the number of staples present in the magazine. Also the described apparatus provides an indication as to when the supply of staples within the magazine is about to be exhausted. Additionally the coiled part of the constant tension spring is easily mounted in position, minimising assembly costs.
Figure 5 is an exploded view of an alternative form of stapling machine in accordance with the invention. Again, this stapling machine is of the "pliers" type. The stapling machine includes an upper cover 30 containing an assembly to which is pivotally connected an anvil carrier 31, by means of trunnions 32 provided at the end of the anvil carrier. The anvil carrier carries, at its forward end, an anvil 33 which is retained in position by means of an anvil retaining spring 34 which defines an aperture 35 which engages a spigot 36 provided on the anvil carrier 31. The anvil retaining spring 34 also includes an upwardly arched portion 37 which engages the under-surface of a staple magazine carrier 38 which is of channel-form, and which has side walls carrying depending lugs 39 defining arcuate recesses 40 adapted to engage the trunnions 32. The side walls of the channel of the magazine holder 39 end with inwardly turned flanges 41 and also each side wall has an arcuate slot 42 formed therein. Also, one side wall, as is visible in Figure 5, has an aperture 43 formed therein which constitutes a "window". Mounted within the magazine holder 38 is a magazine 34 in the form of an elongate channel, the side walls of the channel being in-turned to form flanges 45 at the forward end, thus defining a staple ejection slot 46.
A staple ejector or pusher 47 is provided adapted to slide along the magazine to bias staples towards the ejection slot.
A staple steady 48 which may be formed of an integrally moulded plastics body is provided adapted to lie over the magazine 44 and to steady the staples within the magazine as they move forwardly. A recess is formed in the under-surface of the staple steady 48 to receive the staple pusher 47. The recess is in the form of a channel which defines a path of movement for the staple pusher 47.
A constant tension spring 49 is provided which has two ends each having a spiral portion 50 and a portion 51 inter-connecting the two ends with the spiral portions. The end 51 is adapted to engage an abutment 47', provided for that purpose on the staple pusher.
A guide 52 is provided which defines two circular-sectioned recesses dimensioned to accommodate the spiral portions 50 of the spring 49. The guide 52 is adapted to be received in a recess provided for that purpose, within the staple steady 48. The recess to receive the guide 52 is associated with the recess for the staple pusher. The guide 52 defines a slot 52'. An aperture 53 is formed in the side of the staple steady 48, also to form a window, the apertures 43 and 53 and the slot 52' being adapted to be co-aligned.
In assembling the stapling machine the spiral portions 50 of the spring 49 are inserted in the recesses in the guide 52, and the guide 52 is then mounted in the appropriate recess in the under-side of the staple steady 48. The end 51 of the spring 49 extends across the recess which receives the staple pusher.
The upper part of the staple steady 48 is formed to accommodate snugly a spring 54. The spring 54 has a portion 55 at the forward end thereof which engages an aperture 56 provided in a staple ejector blade 57. The spring 54 comprises a linear part extending from the portion 55. The linear part terminates with an upwardly and forwardly curled region, so that the spring 54 has two substantially parallel portions joined by a "U" bend. The "U" bend abuts a curved recess provided for that purpose on the top of the staple steady 48.
An actuating lever 58 is provided having a bearing 59 defined at substantially its mid-point, the bearing engaging a recess 60 provided for that purpose substantially at the mid-point of the anvil carrier 31. The forward end of the actuating lever 58 carries a roller 60 which passes through the arcuate slots 42 provided in the magazine carrier and which also engages the top surface of the forwardly extending lower portion of the spring 54.
A front plate 61 is provided for the magazine 44 in the form of a plastic moulding that is snap-fitted to the front of the magazine 44, covering the flanges 45. A release catch 62 is provided which is mounted on the front of the housing 30 with the aid of a release catch clip 63. An aperture or window 64 is defined in the side of the main housing 30 adapted to be aligned with the apertures 43 and 53.
It is to be appreciated that by releasing the catch 62 the magazine may slide, under a bias provided by the spring 49, to a position in which the magazine 44 protrudes from the housing 30. The magazine 44 may be grasped so that the magazine may be drawn forwardly out of the housing to replenish the supply of staples. When the magazine is pushed back into the housing, the staple pusher 47 is engaged by the staples within the magazine, and the staple pusher 47 is thus moved towards the right against the bias from the constant tension spring 49. The portion 51 of the constant tension spring inter-connecting the two ends which each terminate in the spiral portions 50 engages the abutment 47' on the staple pusher 47. The spiral portions thus effectively unwind, and the constant tension spring applies a substantially constant tension to the staple pusher 47. The two spiral portions 51 of the spring 49 apply equal forces, and thus the total force applied to the staple pusher 47 is aligned with its axis of movement. There is thus no tendency for the staple pusher 47 to twist and jam.
When the stapling machine has been supplied with staples and the actuating lever 58 is grasped, simultaneously with the housing 30, the actuating lever will move pivotally about the axis defined by the bearing 59 and the recess 60. This will also tend to move the anvil carrier about the axis defined by the trunnions 32 and the recesses 40. The arched portion 37 of the anvil retaining spring 34 would initially be flattened and any paper located between the anvil and the base of the magazine carrier 38 will be effectively gripped by the "pliers" action. Subsequent movement of the actuating anvil 58 will cause the roller 60 to move the lower part of the spring 54 downwardly, thus driving the staple ejector blade 57 downwardly through the staple ejection slot 46, driving a staple from the staple magazine 44 so that the ends of the arms of the staple penetrate the paper and are then clinched by a recess provided on the anvil.
It is to be appreciated that part of the exterior of one of the spiral portions 50 of the constant tension spring 49 can be viewed through the aligned slot 52' and the apertures and windows 64, 43 and 53. This part of the constant tension spring may provide some marking which, when it becomes visible through the aligned windows and apertures, provides an indication that the supply of staples within the stapling machine is about to be exhausted.
Figure 6 illustrates another embodiment of the invention very similar to that illustrated in Figure 5. Like references are used for like parts in Figure 5 and Figure 6 to obviate unnecessary re-description.
The staple ejector blade 57 in the embodiment of Figure 6 has a rearwardly directed spring portion 70, which co-operates with a rigid beam 71 of channel form that is mounted within the main housing 30. Part of the beam is received in a slot formed on the projection on the upper part of the staple steady. The projection defines a recess that accommodates a curved end part of the spring portion 70. The combination of the channel 71 and the spring 70 performs the function of the spring 54 as described with reference to the Figure 5 embodiment.
In the described embodiments of the invention a window to show the number of staples remaining has been described as being provided on one side of the stapling machine. Of course, in alternative embodiments of the invention windows may be provided on both sides of the stapling machine to enable the status of the supply of staples to be observed regardless of from which side the stapling machine is being viewed.
Whilst the invention has been described with reference to a "pliers" type machine it is to be appreciated that features of the invention may be incorporated into a conventional or "desk-top" machine.
The features disclosed in the foregoing description, in the following Claims and/or in the accompanying drawings may, both separately and in any combination thereof be material for realising the invention in diverse forms thereof.

Claims

A stapling machine incorporating a magazine for a strip of staples, means adjacent one end of the magazine defining a staple ejection slot, an ejection blade adapted to eject a staple through the ejection slot, means to actuate the ejection blade, a staple pusher adapted to push staples along the magazine towards the ejection slot and spring means engaging the staple pusher to apply a force to the staple pusher, wherein the spring means comprise a spring strip having one end thereof wound into a spiral coil, there being a cavity to receive and retain said spiral coil in a predetermined position, a part of the spring extending from the spiral coil to the staple pusher.
A stapling machine according to Claim 1 wherein the stapling machine incorporates a further element which engages the staple magazine, the cavity retaining said one spiral coil in a predetermined position being defined on the element which engages the staple magazine.
A stapling machine according to Claim 1 wherein the stapling machine incorporates a staple steady which lies over the magazine, and the cavity is formed on a guide element that is mounted on the staple steady.
A stapling machine according to any one of the preceding Claims wherein a magazine carrier is provided and the staple magazine is slidably mounted on the said magazine carrier so that the staple magazine may move from an operative position to a protracted position.
A stapling machine according to Claim 4 wherein a catch is provided to retain the magazine in the operative position, the arrangement being such that if the catch is released the spring means will cause the staple magazine to move to the protracted position.
A stapling machine according to any one of the preceding Claims in the form of a pliers-type stapling machine.
A stapling machine according to any one of the preceidng Claims wherein means are provided to indicate when the supply of staples within the magazine is about to be exhausted.
A stapling machine according to Claim 7 wherein said means comprise one or more indicia present on the spring strip and a window to permit the spring strip to be viewed, the said one or more indicia being so located that they become visible when the supply of staples is about to be exhausted.
A stapling machine according to any one of the preceding Claims wherein the spring strip has two ends each wound into a respective spiral coil, each coil being maintained in a predetermined position, a respective portion of the spring extending from each respective coil to the staple pusher, the part of the spring strip engaging the pusher inter-connecting the ends of said two respective portions of the spring.
A stapling machine according to Claim 9 wherein each spiral coil is received in a recess defined in a guide element, the guide element being received in a cavity formed on a guide element which guides the staple pusher.