A ROTARY STAPLING MACHINE

Abstract: The invention relates to a rotary stapling machine that comprises a first rotatable roller (2), means (6) co-acting with said roller (2) for holding a U-shaped staple (7) in a predetermined position of orientation, a second rotatable roller (3), and a so-called pad unit (8') for co-action with said second roller (3). The rotatable rollers (2, 3) are adapted to rotate at a peripheral speed which will allow material (1') to be stapled to pass therebetween. Pressing of the staple legs through the material (1') and bending of the staple legs takes place as the material (1) moves between the rotatable rollers. The material (1') passes the first roller (2) so that the staple legs (7a, 7b) will be able to penetrate the material or be pressed therethrough. The pad unit (8') is adapted to receive the legs (7a, 7b), and leg-bending devices (31, 32) function to press the legs together through the medium of mutually opposite forces that act in a plane corresponding to a plane of the staple (7, 7a, 7b, 7c).

Description: TITLE OF INVENTION; A ROTARY STAPLING MACHINE FIELD OF INVENTION The present invention relates generally to a so-called rotary stapling machine, and then more particularly to a stapling machine that comprises a first rotatable roller, a so-called stapling cylinder and a holding device which co-acts with said roller and functions to hold a U-shaped staple in a predetermined position of orientation, said device being re- ferred to as a stapling fork, a second rotatable roller, a so-called counterpressure cylinder, and a pad, which co-acts with said counterpressure cylinder, wherewith the pad and the holding device are mutually so related to the outer cylindrical surface of respective rollers as to be brought to a mutu- ally facing and/or mutually co-acting position in response to rotation of said rollers, said position being one in which the pad is able to bend the legs of the U-shaped staple towards said holding device, and wherewith the rotatable rollers are adapted to allow material that is to be stapled to pass therebetween. The present invention is a further development of the known fact that the pad shall comprise a pad unit which is positioned in or in the immediate proximity of an outer cylindri- cal surface of said second rotatable roller, and which includes moveable leg-bending devices that are able to co-act with and bend respective legs of a staple. 2 DESCRIPTION OF THE BACKGROUND ART A rotary stapling machine of the aforedescribed kind is known to the art. A machine of this kind is adapted to apply sta- pies to a web of material at a predetermined distance along its length and comprises a stapling cylinder, a counterpressure cylinder, a forming drum and a horn which extends between the forming drum and the counterpressure cylinder along the peripheral surface of the stapling cylinder, wherewith the stapling fork co-acts with the stapling cylinder and functions to cut in the region between the stapling cylinder and the forming drum a piece of staple-forming wire material and to form therefrom a U-shaped staple, wherewith the staple is transported by the stapling fork and the stapling cylinder to the region between the stapling cylinder and the counter- pressure cylinder and there fastened to a material web that passes continuously between the stapling cylinder and the counterpressure cylinder, with the aid of a so-called pad carried by the counterpressure cylinder. A stapling machine of this kind is used to staple together the spine parts of a multi-page newspaper, a magazine or like article, and constitutes one of a number of processing stations that process printed articles delivered by a printing machine. The printed paper material or printed article is folded in different ways to form a newspaper, a magazine or the like, and the individual pages of the newspaper, etc., are joined together by spine-related staples. Swedish Patent Specification 506 107 (corresponds to publication US-A 5,474,221) discloses a rotary stapling machine which is comprised of a first rotatable roller ( 2 ) , which co- acts with means ( 6 ) to retain a U-bent staple ( 7 ) in a predetermined position of orientation, and a second rotatable roller (3), which co-acts with a die (8). The die and the means ( 6 ) are mutually so related to the cylindrical surfaces of respective rollers as to enable them, upon rotation, to be brought to a mutually co-acting position in which the legs (7a, 7b) of the U-shaped staple can be bent in a direction towards said means ( 6 ) . The die consists of a die unit ( 8 ' ) , which is located in or in the immediate vicinity of a cylindrical surface (3b) of the second roller ( 3 ) . It includes leg-bending means (22) arranged for a circular movement around an axle beneath said cylindrical surface and capable of co-acting with respective legs (7a, 7b) of the staple ( 7 ) . These are intended to rotate towards said first rotatable roller (2) for the purpose of bending said legs, and then within a region (2b) of a cylindrical surface of said first roller located adjacent said means (6) hold a staple (7). This earlier publication also describes in more detail how the free ends of the legs of a staple can be bent or curved back against a leg-interconnecting part so as to firmly clamp the material or paper sheets, preferably by pressing the ends of the legs against the centre-part of the leg-interconnecting part or web of the U-shaped staple. The rotary stapling machine described in the aforesaid earlier publication is constructed so as to enable so-called "flatly lying staples" to be obtained, wherewith the staple legs are folded to a flat state and bent within a limited region so as to be more or less parallel with the interconnect- ing part of said staple. The present invention comprises a further development of the rotary-stapling machine illustrated and described in the aforesaid earlier publication. In the case of the stapling machine taught by this earlier publication, the staple legs are bent in the close proximity of the paper web with the aid of leg-bending devices that ex- 4 ert obliquely directed forces on the tips or ends of the staple legs. Publication SE-B-7812188-6 (corresponds to publication US-A 4,204,627) is also part of prior art. This publication disclosed a staple closing mechanism for use in a longitudinal stapling apparatus for inserting and closing staples in a product conveyed at a uniform speed. Its object is to provide a staple closing mechanism for a high speed longitudinal sta- pling apparatus. This is achieved by having a rotating cylinder ( 1 ) to carry a first rigid staple shank bending insert (16) and a second, rotatable around its own axis of rotation ( 19 ) , staple shank bending device ( 5 ) . The direction of rotation for the rotatable staple shank bending device ( 5 ) is the same as the direction of rotation for the cylinder (1) carrying the same. The shanks of the staple pass through the product with one shank ( 29 ) coming into contact with the fixed staple shank bending insert (16) whereafter the second shank (31) contacts the rotating shank bending device ( 5 ) . The two shank bending elements co-operate to bend both shanks of the staple ( 20 ) into engagement with the product. SUMMARY OF THE INVENTION TECHNICAL PROBLEMS When taking into consideration the technical deliberations that a person skilled in this particular art must make in order to provide a solution to one or more technical problems that he/she encounters, it will be seen that on the one hand it is necessary initially to realise the measures and/or the sequence of measures that must be undertaken to this end, and on the other hand to realise which means is/are required in solving one or more of said problems. On this basis, it will be evident that the technical problems listed below are highly relevant to the development of the present invention. When considering the present state of the art as described above, it will be evident that a technical problem resides in enabling the so-called pad unit to be given a simpler design and yet still enable the staples to be bent to said so-called flat state. Another technical problem is one of realising the significance of and the advantages afforded by allowing the material to be guided and passed in a stretched state past said first roller (the stapling cylinder) such that the two legs of the staple will penetrate more or less completely through said material . Another technical problem is one of realising the significance of allowing the orientation of respective staples to be guided solely by the material, and to create conditions that will enable the staples to be pressed through the material so that the web part or leg-interconnecting part of said staples will lie in abutment with said material prior to bending the legs of the staple. Still another technical problem is one of realising the significance of adapting the pad unit to receive the tips or ends of said legs, and to provide necessary leg-bending devices that press said legs together through the medium of counter-directional movements and forces that act against central regions of the legs and in a plane corresponding to a plane of the staple. Still another technical problem is one of realising the significance of allowing the engagement points of the counter- directional forces exerted by the leg-bending devices to act within the region of 25 to 75% of those parts of the legs that have penetrated through the material. Another technical problem is one of realising the significance of and the advantages afforded by constructing said leg-bending devices in the form of two plates which can be moved towards and away from each other and which are spaced at a given distance apart. It will also be seen that a technical problem resides in re- alising the significance of and the advantages afforded by allowing the maximum distance between edge surfaces on said plates to only just exceed the distance between the mutually distal surfaces of the legs, and to allow the minimum distance between said plates to be slightly smaller than the distance between mutually facing or mutually proximal leg surfaces . Another technical problem is one of realising the significance of the relative distance of the plates and their direc- tion of movement with respect to the bending sequence of said legs, where a greater distance (greater than the minimum distance) results in a higher terminal angular speed with respect to bending of the legs and a longer frictional distance along the legs than when the plates are spaced at said mini- mum distance. Another technical problem is one of realising the significance of adapting the width of the plates and providing said plates with centrally positioned recesses that function to centre the staple legs in the pad in the final part of the leg-bending sequence. Still another technical problem is one of realising the significance of enabling the material to pass said first roller such that respective staples will fully penetrate the material prior to co-action with the leg-bending devices on said pad, such as to create conditions for developing leg-bending in the bottom plane of the paper web. SOLUTION With the intention of solving one or more of the aforesaid technical problems, the present invention takes as its starting point a rotary stapling machine of the kind defined in 7 the introduction and proposes a structural modification in relation to earlier known techniques which will enable the material to pass a first roller ( the stapling cylinder ) such that the staple legs are able to penetrate the material or be pressed therethrough, and whereby a so-called pad unit is adapted to receive said legs and the leg-bending device will functions to press said legs towards each other through the medium of counter-directional forces that act on centre regions of the legs and in a plane corresponding to a plane of the staple. According to preferred embodiments that lie within the scope of the inventive concept, the engagement points of the oppositely directed forces lie at least within the range of 25 to 75% of those parts of the legs that have penetrated through the material. According to one embodiment of the invention, the leg-bending devices have the form of two plates, which are movable to- wards and away from each other in an axial direction relative to the counterpressure cylinder. The maximum distance between said plates will preferably only slightly exceed the distance between the mutually distal sur- faces of the legs, and the minimum distance between said plates will be only slightly less than the distance between the mutually facing surfaces of said legs. The plates will also conveniently include recesses that func- tion to centre the legs of a staple in the pad unit. ADVANTAGES Those advantages primarily afforded by an inventive rotary stapling machine reside in the provision of conditions which enable a novel pad unit to provide a so-called flattened staple which holds the sheets or pages of a printed article together, with the aid of simple leg-bending devices that act 8 along central regions of said legs during the leg-bending sequence. The primary characteristic features of an inventive stapling machine are set forth in the characterising clause of the accompanying Claim 1. BRIEF DESCRIPTION OF THE DRAWINGS A known rotational stapling machine and an inventive rotational stapling machine having features characteristic of the invention will now be described with reference to the accompanying drawings, in which Figure 1 is a side view of a known rotational stapling machine; Figure 2 is a side view of part of the stapling machine shown in Figure 1, this Figure clarifying those modifications that need to be made to the known machine in order for the known machine to include properties significant of the present invention; Figure 3 is a schematic illustration of a time sequence for obtaining a so-called flattened staple in accordance with the invention; Figure 4 is a perspective view of a recessed plate belonging to said leg-bending devices and functioning to centre the legs of a staple in a pad unit; and Figure 5 illustrates from above that part of the outer cylindrical surface of the counterpressure cylinder in which the pad unit is placed. DESCRIPTION OF PRIOR ART TECHNIQUES Figure 1 is a side view of a known rotational stapling ma- chine. The stapling machine is described in more detail in the aforesaid Swedish Patent Specification 506 107 (corresponds to publication US-A 5,474,221), and reference is made to this publication for a clearer understanding of the basic construction principles of the stapling machine and its Cmodus operand!. Thus, Figure 1 is a greatly simplified side view of a rotary stapling machine that comprises a first rotatable roller 2, or so-called stapling cylinder, means 6 in the form of a stapling fork which co-acts with said first roller 2 and functions to hold a U-shaped staple 7 in a predetermined position of orientation, a second rotatable roller 3 in the form of a counterpressure cylinder or anvil cylinder, and a so-called pad 8 which co-acts with said counterpressure cylinder, wherewith the pad 8 and the holding means 6 are each so related to the outer cylindrical surfaces of their respective rollers as to be brought to a mutually co-acting position upon rotation of said rollers and therewith be able to bend the legs of the U-shaped staple in a direction towards said holding means 6, and wherewith the rotatable rollers are each adapted so as to enable material 1 to be stapled to pass therebetween at a chosen incoming and an outgoing angle of about 5° to the second roller or cylinder 3 or to the counterpressure cylinder. It will be seen from Figure 1 that in order for the stapling machine 1 to function, the machine requires a stapling cylin- der 2 which is mounted for rotation in the direction of arrow "P" about a centre axis 2a, a counterpressure cylinder 3 which is mounted for rotation about a centre axis 3a, and a forming drum 4 which is rotatable about a centre axis 4a. 10 As illustrated, the known stapling machine also includes a plate-like horn 5 which extends between the forming drum 4 and the counterpressure cylinder 3 along the upper peripheral surface of the stapling cylinder 2. The width of the horn 5 is adapted to correspond to the free distance between two legs of a U-shaped staple and co-acts with a stapling fork 6 which is attached to the stapling cylinder 2 and accompanies said cylinder as it rotates. The stapling fork 6 functions to press the two legs 7a and 7b of staple 7 through the paper web 1 in the region "A", in a direction towards the anvil- acting pad 8 fixed in the counterpressure cylinder 3. However, the stapling fork 6 can take a position 6a in the region "B" between the stapling cylinder 2 and the forming drum 4 and there cut a length of staple-forming wire-like material 10 and simultaneously form a U-shaped staple which is carried by the stapling cylinder to the region "A" between the stapling cylinder and the counterpressure cylinder and there fastened to a material web 1 passing between the stapling cylinder and the counterpressure cylinder. The stapling fork is arranged for movement along a path 11, at least in the region "B" between the stapling cylinder and the forming drum, therewith to cut said wire-like material 10 and form a staple 7. The stapling fork 6 moves in this respect along a path 13 within the regions "A" and "C" . DESCRIPTION OF EMBODIMENTS AT PRESENT PREFERRED Figure 2 is an enlarged view of the regions "A" and "C" according to Figure 1 and shows features associated with an inventive stapling machine in more detail. A feature significant to the present invention is that the web of material to be stapled must follow a different path to that followed in Figure 1, hence is the material web referenced 1 ' in figure 2 and the path in which the paper web 11 moves is governed through the medium of a deflecting roller 20 (not shown in detail in Figure 2 ) , and that the horn 5 is slightly shortened. According to the invention, the staple 7 is able to commence penetration of a stretched web 1 ' , at or roughly at the line 21, and to effect a successive penetration sequence within an angular range referenced 22. Figure 2 illustrates more precisely a position in which the major parts of the legs of the staple 7 have penetrated the web 1 ' and in which the ends of the staples have passed slightly into the pad unit 8 ' . The leg-bending sequence and the leg-bending function takes place within an angular region referenced 23. It will be evident from Figure 2 that the web of material 1 ' shall be able to pass the first roller 2 and lie against said roller in a manner which will allow the ends or tips 7a' and 7b 1 of respective legs 7a, 7b to penetrate the web 1' or be pressed therethrough and to displace the staple 7 so that the leg interconnecting part 7c of said staple abuts, or at least almost abuts, the web 1' prior to commencement of the leg- bending sequence. It is necessary to this end to stretch the web 1 ' to a given extent so that said web is able to form a support for the staple 7, and to deflect the web l 1 around the stapling cylinder 2 at an angle of 5°, for instance. Figure 3 illustrates different time sections of the leg-bending sequence or function. The illustrated position between the staple legs 7a, 7b and the abutment of the leg-interconnecting part 7c with the web 1 ' and the orientation of the ends or tips 7a ' , 7b ' of respective legs between the leg-bending plate-like devices 31, 32 at time "tl" can be considered to essentially correspond 12 to the setting shown in Figure 2, where a pad unit 8' is adapted in accordance with the invention to initially receive said legs 7a, 7b obliquely. This obliqueness of the legs 7a and 7b in relation to the pad is "straightened out" during continued rotation of the rollers and the legs become straight in relation to said pad at the tangential point of the rollers 2 and 3. In the illustrated case, the leg-bending devices have the form of two mutually identical plates 31, 32, the nature of which will be described in more detail hereinafter with reference to Figure 4. It will be evident that at time point "tl", the two plates 31 and 32 are spaced apart at a distance (a) which is only slightly greater than the distance between the mutually distal surfaces of the legs 7a, 7b. This position is designated the "maximum" distance (a) between said plates 31, 32. This distance may beneficially be a fixed distance. It is assumed that the pad unit 8 ' is in line with the outer cylindrical surface 3b of the roller 3, and that the distance "c" between the outer surfaces of the rollers 2 and 3 is relatively large in this case. At time point "t2", the distance (a) at time point "tl" will have decreased to the distance "b" between said plates 31, 32, this latter distance "b" being slightly shorter than the distance between the mutually facing surfaces of the legs 7a, 7b. This distance "b" is referred to as the "minimum" distance and may conveniently be adjustable, as made more apparent hereinafter. The distance "c ,M between the rollers 2 and 3 at time point "t2" has now decreased. It can be assumed that at time point "t2", the plates 31 and 32 will have the illustrated position during the whole of the 13 continued leg-bending process and at time point "t3" when the pad unit 8 ' and the staple 7 have passed to the tangential point of the rollers 2, 3, the ends 7a', 7b' of the staples will face towards each other and a so-called flat staple will have been formed. At time point "t3", the distance between the rollers 2 and 3 will have decreased so as to correspond to the thickness of the web 1 ' , or slightly less than said thickness . At time point "t4", the plates 31, 32 will have been moved apart by means of a spring 33, or some like means, so as to again be positioned with the maximum spacing (a) therebetween. Since the pad unit 8' and the roller 2 have passed the aforesaid tangential point, the distance "c" between the rolls 2 and 3 will have increased and the paper web 1 ' now leaves the rollers 2 and 3. As will be understood, the selected distance "b" can be var- ied according to requirements, and the type of material and the thickness of the legs 7a, 7b. It will also be understood that movement of the plates 31 and 32 towards each other and axially in relation to the roller 3 can cease between the time sections "tl" and "t2", in other words earlier than at the time point "t2", such that the plates will take their final position at a greater distance "b" . On the other hand, said movement may continue within the time sections "t2" to "t3" and may even be extended to stop at the time section "t3". A small difference "a"-"b" provides a long slide path for the edge surfaces 31a, 32a of the plates 31, 32 along the mutually distal outer surfaces of the legs 7a, 7b with a high angular speed for folding of the legs in the final stage of the process. 14 A large difference "a"-"b" provides a shorter slide path for the edge surfaces 31a, 32a of said plates 31, 32 along the mutually distance outer surfaces of the legs 7a, 7b with a lower angular speed for folding of the staple legs in the fi- nal stage of the stapling process. According to the invention, the leg-bending devices or plates 31 and 32 shall be capable of acting as pressure surfaces that press the legs 7a, 7b towards each other through the me- dium of counter-directional forces acting with normal forces on the staple part 7c that interconnects the legs 7a, 7b, and in a plane corresponding to a plane of the staple (7), 7a, 7b, 7c. Thus, it can be assumed that the counter-directional forces will be applied in regions corresponding to 25 to 75% of those parts of the legs that have penetrated the material, and that the leg-bending devices will be comprised of two plates 31, 32 that can move towards and away from each other axially in relation to the roller 3, in a way that in itself is previously known. Figure 4 shows one plate 32 in perspective. The illustrated plate 32 is identical with the plate 31 and includes in one edge 32a a central recess 32a' which functions to centre the leg of the staple in the pad unit 8 ' , at least during the time sections "t2" to "t3". Thus, a significant feature of the invention is that the ma- terial 1 ' shall be pressed against the roller 2 as it passes said roller, and that respective staples 7 shall fully penetrate the material 1 ' prior to co-action of the staple legs with the leg-bending devices 31, 32 of the pad unit 8'. Referring again to Figure 3, it will be understood that the plates 31, 32 will preferably move smoothly and gently towards each other, preferably with the aid of a cam guide. 15 If movement of the plates is commenced at time point "tl", said movement can be controlled to reach a final stage within the time section "tl"-"t2" or within the time section "tl"- "t3". The final position may be a small difference "a"-"b", in accordance with Figure 3, or a large difference, for instance "b" equals zero. Movement of the plates 31, 32 within the region "g" may either be constant or may vary, such as in the case of a high initial speed and a low terminating speed, or vice versa. Alternatively, plate movement may be constant within a region "g" / depending on the cam guide that is chosen. The plates may also be returned through the medium of a camming action. In the Figure 3 illustration, the region "g" is 25-75% of those parts of the legs that have passed through the material, which is a suitable range although a range beginning at a value beneath 25% is also conceivable. The measure 25% relates to the distance from the tip or end 7b' of the leg 7b to the region "g", while the measure 75% relates to the distance from the tip or end 7b' and the region "g". Figure 5 illustrates schematically the outer cylindrical surface 3b of the counterpressure cylinder 3 within the region of the pad unit 8 ' . It will be seen that the plates 31 and 32 are inserted in a channel or groove 51 having a width "e" which exceeds the wire diameter "f" of the staple legs 7a, 7b, by a factor of 2-5, preferably a factor of 3-5. The factor will preferably be about 4. 16 The recess 32a' in the edge 32a of the plate 32 shall be capable of guiding the staple legs 7a to a centred position, at least during the latter part of the leg-bending process. It will be understood that the invention is not restricted to the aforedescribed and illustrated exemplifying embodiment thereof, and that modifications can be made within the scope of the inventive concept as defined in the accompanying Claims.

Claims: 17 CLAIMS 1. A rotary stapling machine comprising a first rotatable roller, means co-acting with said roller to hold a U-bent staple in a predetermined position of orientation, a second rotatable roller, and a so-called pad that co-acts with said second roller, wherewith said pad and said means are so related to the outer cylindrical surfaces of respective rollers as to be brought by rotation of said rollers into mutually co-acting positions in which the legs of the U-shaped staple can be bent in a direction towards said means, and wherewith the rollers are adapted to rotate at a peripheral speed such as to enable material which is to be stapled to pass therebetween, and wherewith penetration of the staple legs through said material and bending of said legs takes place during movement of said material between said rotatable rollers, and wherewith said pad is comprised of a pad unit positioned in or in the immediate vicinity of an outer cylindrical surface of the second rotatable roller and includes movable leg-bend- ing devices that co-act with respective staple legs, where the arrangement is such that said material is caused to pass said first roller such as to enable the staple legs to penetrate said material or be pressed therethrough, c h a r a c t e r i s e d in that the pad unit is adapted to receive said penetrating legs; and that the leg-bending devices function to press said legs towards one another through the medium of mutually opposite movements and forces that initially act against the centre regions of respective legs and in a plane corresponding to a plane of the staple. 2. A machine according to Claim 1, c h a r a c t e r i s e d in that the oppositely acting forces are applied in a region corresponding to 25-75% of those parts of the legs that have penetrated through the material. 3. A machine according to Claim 1, c h a r a c t e r i s e d in that said leg-bending devices have the form of two plates which are movable towards and away from each other. 18 4. A machine according to Claim 1 or Claim 3, c h a r a c t e r i s e d in that the maximum distance between said leg-bending devices only slightly exceeds the distance between the mutually distal surfaces of the legs; and in that the minimum distance between said leg-bending devices is less than the distance between the mutually facing surfaces of said legs. 5. A machine according to Claim 1, c h a r a c t e r i - s e d in that said leg-bending devices include recesses for centring the staple legs in the pad unit. 6. A machine according to Claim 1, c h a r a c t e r i s e d in that the material is arranged to pass and lie against said first roller such that the legs of respective staples will fully penetrate said material prior to co-action of the staple legs with the leg-bending devices in said pad unit. 7. A machine according to Claim 4, c h a r a c t e r i s e d in that the maximum distance is a fixed distance. 8. A machine according to Claim 4, c h a r a c t e r i s e d in that the minimum distance is variable. 9. A machine according to Claim 1, c h a r a c t e r i s e d in that movement of the leg-bending devices is controlled by a cam guide or like means.

Inventors: MEDIN CALLE MIKAEL, MEDIN, CALLE, MIKAEL
Applicants: MEDIN CALLE MIKAEL, TOLERANS INGOL HOLDING AB, MEDIN, CALLE, MIKAEL
Application year: 1999
Main classification: B27F7
IPC codes: B27F7, B42B4