A stapler for driving metal staples

Abstract: A stapler for driving metal staples which are fed through a guide channel to an ejecting channel under the action of a pusher member moved by resilient means on a pair of walls located inside the stapler frame, on said walls there being positioned a strip of metal staples. The inner walls (40) and one side wall (36) of the stapler are shorter than bottom wall (66) of guide channel (34), so that it is possible to make pusher member (30) to back up until it disengages from inner walls (40) and may be rotated substantially 90° allowing the insertion of a new staples strip once the previous one has been used up.

Description: This invention concerns a stapler for driving metal staples. Staplers of the above type are already known and it is known as well that these tools are loaded with "strips" of metal staples which are inserted into a suitable feeding channel ending with an ejecting channel. The staple strip is forwarded towards the ejecting channel under the action of a suitable pusher, whereby the metal staples get positioned within the ejecting channel, one at a time, and they are pushed out therefrom by the action of an ejecting blade. The member which forwards the metal staple strip towards the ejecting channel, i.e. the pusher member mentioned above, is substantially comprised of a slider which is slidably mounted within the metal staples feed channel, and is subjected to the action of an operating spring which is coiled around a small rod having a portion of the slider slidably mounted thereon , said spring being engaged at one end with said portion of the slider, while at the opposite end it abuts against a stapler rear stationary wall. In staplers of the subject type it is known how highly uncomfortable it is to introduce a new staple strip in the feeding channel once the previous one has been used up. The above operation requires the slider to be taken out of the stapler completely, together with the members associated therewith enabling the slider to slide within the feed channel and controlling said sliding operation. The requirement to take the pusher member and the members associated therewith completely out of the stapler may cause several problems and, among these, some damages to the slider, for instance when it is accidentally dropped or because of a wrong operation by the user. Also the operation of reassembling the pusher member on the stapler may prove to be extremely discomfortable once the staple strip has been introduced into the feed channel, and this operation as well may involve wrong moves by the user, which in turn may cause the stapler to jam thereafter. GB-A-652119 discloses a stapler for driving metal staples according to the preamble of the present claim 1, which however has a pusher member engaging the staple strip in only one restricted zone, i.e. a strip contacting member which is laterally offset from the strip axis. As a consequence when the staple strip is almost at end and adjacent staples are unstuck to each other, as usually happens, the staple legs may tilt backwards with consequent jamming thereof in the ejection zone which becomes clogged. Although this prior patent provides for preventing a possible jamming by causing some staples at the end of a strip not to be ejected, but to remain in the magazine, when the pusher is moved backwards for loading the magazine these remaining staples may assume a transverse position with additional inconveniences. Furthermore the guides of the staple strip according to GB-A-652119 are places outside of the stapler, and are different from the guides of the pusher member. Therefore in GB-A-652119 only a given height of the tacks or staples can be adopted and the ends of the staples are rubbing against the slot bottom with a friction that may cause the legs of loose staples to rotate thus possibly giving rise to the above-mentioned jamming. It is an object of the present invention to provide a stapler for driving metal staples which overcomes the above drawbacks and difficulties and not only does not require either the pusher member or the members associated therewith to be taken out of the stapler by providing a pusher member handling arrangement whereby a new staple strip may be inserted while the pusher member and the handling members associated therewith remain assembled on the stapler, but also obviates the inconveniences shown by GB-A-652119. The stapler according to the features of the characterizing portion of claim 1 is in fact provided with a pusher member acting onto the whole profile of the staple strip, along its longitudinal axis and parallel to the guides. These guides, which are the same for the staple strip and the pusher member are formed between the inner walls of the stapler which, as well as one of the side walls, are shorter than the bottom wall of the guide channel, thus allowing the stapler to be loaded from the side and to be used with staples of different height size. There is a reduced danger of jamming and the staple strip is always driven and located beyond the zone of possible interference with the pusher. The features as well as the advantages of the stapler according to this invention will become apparent from the following detailed description of a non limiting embodiment thereof, given with reference to the attached drawings wherein: Figure 1 is a side elevational view of a stapler according to this invention; Figure 2 is a side longitudinal sectional view of the stapler according to this invention; Figure 3 is a partially cutaway perspective view, which shows the pusher member in the operating position; Figure 4 is a partial perspective view of the stapler according to this invention, which shows the pusher member in the position wherein it enables a new metal staple strip to be loaded; Figure 5 is a perspective view of the stapler which shows the step of loading a new staple strip. The embodiment considered herein is a manually operated one, but the same innovative concept remains applicable for staplers in general, electrically operated, pneumatically operated, and the like. Referring now to the above figures, the inventive stapler includes, in a known way, a suitably shaped frame 10, so that the same may be properly gripped and operated, and carrying in the top portion thereof a pivotally mounted control lever 12 whose end located inside frame 10, and shown at 14, engages within a slot 16 of a metal blade 18 comprising the metal staple ejecting member and being, for that purpose, slidably mounted within an ejecting channel. In a second slot 20 of blade 18 there is also engaged the end of a leaf spring 22, having the opposite end thereof connected to a stationary pivot pin 24. Leaf spring 22 engages, at an intermediate portion thereof, with an inner projection 26 of frame 10, which enables spring 22 to get loaded once control lever 12 is rotated according to arrow F, causing simultaneously ejecting blade 18 to be raised. Reference number 28 indicates a return spring for returning control lever 12 to the starting position, once a staple has been driven. The above description is known per se, and no further details will be given herein. The inventive stapler further includes a pusher member for a metal staple strip 32, shown in general at 30, which is slidably mounted within a feeding channel, shown in general at 34 in Figure 4. Channel 34 includes, in a way already known, a pair of outer side walls 36, 38 for guiding strip 32, and a pair of inner walls 40 extending longitudinally of channel 34 and comprising simultaneously a support and a guide for strip 32 towards the ejecting channel. Pusher member 30, which is described in detail in the following, is slidably supported by a small longitudinal rod 42 having a spring 44 wrapped therearound for providing the forwarding motion of pusher member 30 towards the staple ejecting channel, one end of said spring being engaged with pusher member 30, while the opposite end is in engagement with a stationary rear projection 46 of stapler frame 10. Pusher 30, provided for instance as a unitary body, comprises essentially a lower substantially U-shaped portion 48 which is applied across inner walls 40 and which comes into engagement, at the front end thereof, with the rear end of strip 32. Portion 48 of pusher member 30 tapers towards the rear portion of the stapler, as it is apparent in particular in Figures 2 to 4. Pusher member 30 further includes an upper portion 50 comprising a sleeve 52 slidingly mounted on stationary rod 42, and a projection 54 to be described in the follow ing. Spring 44 has one end thereof engaged with the rear portion of sleeve 52. Projection 54, which is longer than sleeve 50, has a substantially prism-like shape, with a substantially triangular cross-section having a sloping side, whereby it has a decreasing cross-section starting from sleeve 52. At one end of projection 54 there is provided a substantially rectangularly shaped extension 56 radially positioned relative to projection 54. On extension 56 there is provided an opening 58 which, in the embodiment described herein, has a rectangular cross-section. Side wall 38 extends above guide channel 34, with a cover wall 60 which extends partially over said channel 34 reaching a position substantially above small rod 42, in order to prevent undesired hand contacts with sleeve 50 and spring 44. According to this invention, cover wall 60 is interrupted at the rear portion of the stapler, and the rear end 62 thereof is folded upwards, for reasons to be explained in the following. Furthermore, folded end 62 has a projection or tooth 64 whose function will become apparent in the following as well. According to a further feature of the inventive stapler, both inner walls 40 of guide channel 34 and outer side wall 36 are shorter than bottom wall 66 and more particularly they have such a length as to stop before the position where upper cover wall 60 is interrupted. From the above it should be apparent that, thanks to the stapler of this invention, loading a new staple strip is made extremely fast and easy, as it will be explained in the following. Once a staple strip 32 has been used up, as it is shown in Figure 2, it is enough, by operating on extension 56 of pusher 30 located substantially outside stapler frame 10, to move pusher 30 back until portion 48 thereof comes out of engagement with inner walls 40, in which condition pusher 30 may be controlled to rotate around small rod 42 until it reaches the position shown in Figure 4. Rotation is made possible owing both to the reduced length of inner walls 40 and of side wall 36, and to the slope of the rear end of cover wall 60. Concerning the above it should be noted that the slope of the front face of projection 54 substantially matches that of said end 62 of wall 60, whereby an abutment is provided which makes it easier and guides the insertion of tooth 64 within opening 58. It should also be noted that, when pusher 30 is in the position rotated substantially 90°, as it is shown in Figures 4 and 5, the side which is now located downwards remains located higher than the height of inner walls 40, whereby the rear loading of a new staple 32 is made possible. Once the strip has been introduced in guide channel 34 projection 56 is operated again causing the latter to disengage from tooth 64 and pusher 30 to be subsequently rotated all the way to the starting position, wherein it can be positioned again on inner walls 40 and it can perform again its pushing action on strip 32. It should eventually be apparent that variations and/or modifications may be made to the stapler according to this invention, without exceeding the scope of protection of said invention.

Claims: A stapler for driving metal staples which are fed through a guide channel (34) to an ejecting channel under the action of a pusher member (30) controlled by resilient means (44), said pusher member being moved by said resilient means on a pair of walls (40) located inside the stapler frame (10), on said walls there being positioned at least a strip (32) of metal staples, said pusher member (30) having an extension (56) projecting outside stapler frame (10), by means of which it is possible to make pusher member (30) to back up all the way until it disengages from inner walls (40) and may be rotated substantially 90° so that said extension (56) comes into engagement with stapler (10) locking means adapted to temporarily retain pusher member (30) in the rotated position, characterized in that said pusher member (30) acts on the whole profile of the staple strip (32) along its longitudinal axis and parallel to the inner walls (40), said stapler inner walls (40) and one (36) of the stapler side walls having a length shorter than bottom wall (66) of guide channel (34), thus forming an opening for loading a staple strip on to the inner walls (40) and allowing for rotation of the pusher member (30), and said rotation of pusher member (30) additionally being permitted by the upward sloping rear end (62) of an upper cover wall (60) of guide channel (34). The stapler of Claim 1, characterized in that pusher member (30) includes an upper portion (50) which substantially comprises a sleeve (52) slidably mounted on a small stationary rod (42) carrying said resilient means (44) engaged with sleeve (52), and a projection (54) longer than sleeve(52) and provided, at one end thereof, with an extension (56) projecting outside stapler frame (10). The stapler of Claim 2, characterized in that extension(56)has an opening(58), and a tooth(64) provided on the folded up end portion (62) of cover wall (60) may engage therein, when pusher member (30) has been brought to the rotated position. The stapler of Claim 2, characterized in that the face of projection (54) which can be seen has a decreasing cross-section starting from sleeve (50). The stapler according to Claim 4, characterized in that the slope of the face of projection (54) which can be seen is substantially the same as that of end (62) of cover wall(60)of guide channel (34). The stapler of Claim 1, characterized in that, when pusher member (30) is in the rotated position, the side thereof located downards is higher than the height of inner walls(40)whereon the metal staples are fed.

Inventors: MAESTRI ELIO, MAESTRI, ELIO
Applicants: MAESTRI FIGLI SPA ROMEO, ROMEO MAESTRI & FIGLI S.P.A.
Application year: 1990
Main classification: B25C5
IPC codes: B25C5