Patent Publication Number: US-3876129-A

Title: Staple stitchers

Description:
United States Patent [1 1 nn Bulka {45} Apr. s, 1975 {5 STAPLE STITCHERS 1.983.384 0/1934 McClure 227/90 x 1.531985 ll 95() N1 h .127&#39;90 [75] Inventor: Raymond l. Bulka, Oak Lawn. Ill. H I  
 [73] Assignee: McCain Manufacturing Corp&#34; Primary ExuminerGranvilie Y. Custer Jr.  
  Chicago. Ill Attorney. Agent, or FirmKinzer Plyer. Dorn. 22 Filed: Jan. 24, 1974 McEmhm 2| A .N ,1 436.210 1 pp 0 57 ABSTRACT A stitcher head having a swivel staple support mem&#39; 52 l. S 3;??? ber. driver and driver bur IS so constructed that the 5 V I V 1 V I. 5&#39; support member rather than the driver shifts the 8] Field of Seal-(h 90 swivel while the driver bur rather than the driver shifts {56] References Cited the support member. thereby unioading the driver to a considerable extent. UNITED STATES PATENTS 1.301402 4/191; Maynard 227M 4 Claims 9 Drawing Figures STAPLE STITCHERS This invention relates to a stitcher head of the kind which feeds. cuts and shapes wire to the form of a staple and then clinches the staple to the work.  
  Stitcher heads of the foregoing kind are customarily used to join signatures to form a book. A signature is a folded sheet. In forming books from signatures. the signatures may be gathered one atop another on a socalled saddle conveyor. The signatures so collected are delivered to the stitcher head where the backs of the signatures are joined by staples as disclosed in McCain US. Pat. Nos. 3.275.2l0 and 3.542.271.  
  Known stitcher heads are employed in stitching signatures. The stitcher head is of the kind disclosed in U.S. Pat. No. l.302.-&#39;l()2. The length of wire from which the staple is formed is cut and positioned vertically in a groove of a swivel which is then turned to dispose the wire length in a horizontal position. Afterwards the bender bar shapes the wire to U-form while the wire is held by the swivel. Next. a driver bar carries a related driver downwardly. The free end of the driver engages the swivel and causes it to be retracted. As the swivel is retracted. it releases the bent wire to a pivotal support member; the legs of the bent wire are guided by grooves in the bender bar. The driver and support member cooperate to square off the crown of the staple. Further descent ofthe driver and driver bar is characterized by the end of the driver engaging the support member to move the latter to a retracted position and at the same time the driver forces the wire into the work to which the staple is clinched.  
  The free end of the driver does a great deal of work in the known stitcher head: in addition to driving the staple into the work it is responsible to move both the swivel and the support member to retracted positions and to cooperate with the support member in squaring off the staple.  
  It was mentioned above that the bender bar in the known device has grooves for guiding the legs of the shaped wire. These same grooves serve as guides for vertical ribs on the sides of the driver and in fact the ribs on the driver are heavily loaded during descent as will now be explained.  
  During high speed operation (e.g.. 250 cycles per minute) using thin wire. frequent unexplained failures of the driver have been encountered. Specifically, the guide ribs shear off. This failure can be traced to small but significant forces tending to twist the driver out of a vertical plane. Thus. the ribs on the driver are only as thick as the wire being fed. because both the ribs and wire are guided by the grooves in the bender bar. With this in mind, and bearing in mind that the driver is bound to experience horizontal components of force in opposite directions as its free end displaces the swivel in one direction and the support member in the opposite direction, the reason for failure becomes apparent. namely. for thin wire and at high speeds the thin driver ribs ultimately undergo fatigue failure because of the rapid, repeated twisting in successive machine cycles. The object of the invention is to avoid this failure and thereby impart prolonged life to the driver. More specifically. it is an object of the present invention to remove from the driver the work load of displacing the swivel and the support member and to transfer part of this work to the heavier driver bar so that the only work of the driver is to cooperate with the support to straighten the crown of the wire staple and to drive the staple into the work. Yet more specifically it is an object of the present invention to use the staple support member to displace the swivel and to extend the free end of the driver bar beyond the free end of the driver so that the driver bar. rather than the driver. will displace the support member.  
  Other and further objects of the present imention will be apparent from the following description and claims and are illustrated in the accompanying drawing which. by way of illustration. shows a preferred embodiment of the present invention and the principles thereofand what is now considered to be the best mode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be made as desired by those skilled in the art without departing from the present invention.  
 In the drawing:  
  FIG. I is a sectional view of a stitcher head constructed in accordance with the present invention.  
  FIG. 2 is a detail sectional view of an enlarged scale compared to FIG. I:  
 FIG. 3 is an end view of the swivel and related parts;  
 FIG. 4 is an elevation of the staple support member;  
  FIG. 5 is a view at the underside of the driver and driver bar;  
 FIGS. 6 and 7 are elevations of a slide; and  
 FIGS. 8 and 9 are elevations of the driver bar.  
  The description to follow in many instances repeats parts of the disclosure in US. Pat. No. 1.301.402. and in fact. some of the same reference characters are employed. sufficient to identify parts ofthe known stitcher head with which the present invention is concerned.  
  FIG. I shows a section of the bonnet B of a stitcher head conforming generally to US. Pat. No. 1.302.402. On the forward end ofa drive shaft S. FIG. I. is a crank 8 carrying a wrist pin 9 through which motion is transmitted to the reciprocating elements in the stitcher head or bonnet B. The reciprocating elements consist essentially of a driving bar D. a driver bar D&#39; connected to be reciprocated therewith. a staple driver D carried on the lower end of the driver bar D. and a staple former or bender bar F arranged to reciprocate independently of the other sliding parts. The bender bar F is of rectangular. plate-like construction with splines or ribs f. FIG. 5, on its opposed vertical edges fitted to slide in corresponding grooves 13, FIG. 1, in the sides of the bonnet B. In FIG. 1 a portion of one side of the bender bar is cut away to reveal the driver and driver bar.  
  The driver bar D is mounted to slide in the slotted front face of the bender bar F. FIG. 5, noting that FIG. 5 is a view looking upwardly from the bottom of the structure in FIG. 1. The driver bar D&#39; is coupled to the driving bar D at its upper end. FIG. 1, by a tongue-andgroove connection shown at 14.  
  The driver D is fitted to the front of the driver bar D at its lower end as by a spring clip 10, FIG. 9, fas tened to the forward face of the driver bar D. the spring clip free end fitting in a pocket (not shown) in the rear face of the driver D The driver D is merely a flat plate of hardened metal, loosely supported but guided in the manner to be described. The opposite. vertical sides of the driver D are provided with thin ribs or splines 15, FIG. 2, which slide in corresponding grooves formed in the sides of a slot in the bender bar F. Partly in this manner the driver bar D and its connected driver D are held in place on the front of the bender bar F while being adapted to slide in relation thereto. Unlike the known construction. however. the guide ribs on the driver do not take any load but ser\e merely as guide as will be explained.  
  As described in the aforesaid patent. the bender bar F is cut away (bifurcated) at the bottom. forming two parallel. depending legs or extensions 16. FIG. 5. adapted to straddle a cylindrical swivel 17, which is held in a swivel holder I8 on the front of the bonnet B. The swivel serves as an anvil for shaping the staple when the bender bar is reciprocated downwardly in the guiding grooves 13. The swivel or anvil I7 is arranged to rotate as well as to slide axially in its bearing holder 18 to cooperate with the bender bar F to form the staples in the known manner.  
  As described in US. Pat. No. 1.302.402. the swivel at the inner end has a slot 19 for holding the wire to be bent into the staple. The wire feeds down through the slot 19 from above. when the swivel is rotated to orient the slot 19 vertically. and a length is severed from the main length of wire.  
  After the wire has been cut off in a length appropriate to the size of staple required. the swivel 17 is rotated to bring the severed wire W. FIG. 1. into horizontal position beneath the bender bar F as shown in FIG. 1. As the bender bar descends the ends of its legs 16 will strike the extended free end portions of the length of wire projecting beyond the sides of the swivel 17, causing the wire to be bent downwardly to form the opposite parallel legs of the staple ST as shown in FIG. 2.  
  As the bender bar F continues to descend. after completing the formation of the staple ST. the swivel 17 is forced from its extended or operative position to a retracted position as hereinafter described As the swivel or anvil I7 is thus retracted it releases the staple from its cross slot 19 (as described in US. Pat. No. 1.302.402) but the legs of the staple are held in the grooves 15 ofthe bender bar F. FIG. 5. The formed staple is maintained in this position by a pivotal support member 20 hinged on the back ofthe bender bar F and having an inclined upper surface 21 terminating in a toe 22. FIG. 2. adapted to enter between the legs 16 of the bender bar F.  
  As shown in FIG. 1. the staple support member 20 is provided at its heel with a pin 23 adapted to ride on the cam face 24C at the underside of a cam block 24 when the driver bar has descended to a point where the pin 23 is aligned with the cam face 24C. The staple support member is biased to swing counterclockwise, FIG. 1, by a plunger 25 slidably mounted in a bore 26 at the upper end of the support 20 under the influence of a spring 27. The plunger pin 25 bears against the lower end of another plunger 28 slidably mounted in a block 29 which operates the bender bar as described in US. Pat. No. l.302.402.  
  After the staple is formed. and while it is being held in the bender bar F. with the bottom of the latter pressed against the work. assumed to be a group of signatures SG. FIG. 2, the driver bar D&#39; descends and the driver D forces the staple down through the work SG in the usual manner. FIG. 2. In accordance with the present invention, the lower free end 30 of the driver bar. FIG. 2, is extended beyond the free end of the driver. Therefore, as the lower end 30 of the driver bar D&#39; comes into contact with the inclined upper face 21 of the staple support member 20 in its operative or advanced position. the driver bar free end 30 forces the support 20 back to a retracted position to allow the staple to slide off the support 20. Thus. the driver bar and not the driver is responsible for moving the support 20. to its restored or retracted. inoperative position.  
  After the staple has been driven through the work and set in place for clinching over its ends as described in the aforesaid patent. the bender bar. and shortly thereafter the driver bar. start to ascend. and as the former moves upwardly the staple supporter 20. in retracted position. travels with it.  
  It has already been noted that the free end of the driver bar D is extended, compared to the known stitcher. so that the driver bar and not the driver is re sponsible for camming the support member 20 from its operative or advanced. staple supporting position to its released or retracted position. The driver is unloaded to that extent and is further unloaded as will now be described The swivel 17, as noted. is arranged for axial as well as rotary movement in a swivel holder 18, FIGS. 1 and 2. The swivel is biased by a spring means schematically shown at 35, FIG. 1. so as normally to be disposed in an operative position to present the cut piece of wire W to the descending bender bar. the legs 16 of which. FIG. 5. generally shape the wire to U-form. In the known device. the free or lower end of the driver D was responsible for engaging the tapered inner end 36 of the swivel. forcing it to a retracted position at the time the support member 20 shifts to the operative position shown in FIG. 2 to receive the bent wire from the swivel. This action of the driver, as explained above, contributes to driver failure and is avoided under the present invention by relying on movement of the support 20 into operative position. toward the swivel. to displace the swivel to its retracted position. In accomplishing this. a slide 38, FIGS. 1 and 2, is supported in the swivel support 18.  
  The slide 38 has a horizontal leg 39 provided with guide flanges 41, FIG. 7, which fit in corresponding grooves 42G formed within the swivel support. The slide has an inner. dependent element in the form of a leg 42 in position to be struck by the toe 21 of the staple support member 20 and additionally includes an outer. vertically extending leg 43 which is disposed between the outer end 44 of the swivel support and a cap 45 on the outer end of the swivel. Inward movement of the slide is limited by a stop surface 46 within the swivel support.  
  When the driver has descended sufficiently to present the pin 23 on the staple support member to the cam surface 24C, FIG. I, the support member swings to the right. FIG. 1, and the toe 21 thereof is of sufficient extent to strike the leg 42 of slide 38, shifting the swivel to its retracted position, FIG. 2, allowing the driver D to clear and freely pass the innermost end of the swivel without striking the swivel. At the same time. the jaw 19 of the swivel is displaced from the partly shaped staple ST which drops onto the upper sloped surface of the staple support member.  
  Thus, further loading of the driver D heretofore entailed in shifting the swivel. is eliminated, but nonetheless the dimensions are such that as the driver bar and driver further descend. FIG. 2, the crown of the staple supported by member 20, is squared off by cooperation between the free end of the driver D and the staple support 20 concurrently as the free end 30 of the driver bar engages the support member to shift the latter clockwise to its retracted position.  
  When the driver D has cleared the swivel on the return stroke. after emplacement of the staple in the work 56. the spring means (present in the known stitcher head) restores the swivel l7 and slide 38.  
  The brunt of the work of displacing the staple support member. having been transferred to the driver bar D. the latter is provided with side flanges 47. FlGi 9. which fit in guide grooves 48. P16. 5. formed in the bender bar. As further assurance to relieving the driver D from as much work as possible. the ribs 15 on the driver D are so located. to fit grooves in the bender bar as shown in FIG. 5, that a slight gap is established between the opposed surfaces of the driver bar and driver I claim:  
  1. ln 2! wire stitcher head having a swivel for supporting a length of wire from which a staple is to be shaped by a bender bar reciprocal along a path normal to the axis of the swivel, and a driver carried on a driver bar for driving the shaped staple into the work. wherein the swivel is to be shifted laterally to clear the path of the driver while at the same time releasing the shaped wire to a support member pivotally mounted on the bender bar, said support member being moveable toward the swivel to an operative position to receive the shaped wire and being moveable away from the swivel to a retracted position. the improvement comprising: a slide engaging the swivel to shift the swivel laterally free of the path of the driver. and said slide having an element in the path of the support as it moves toward the swivel whereby the support is effective to laterally shift the swivel when the support engages said element,  
  2. A stitcher head according to claim I further improved in that the driver bar has an end extended beyond the end of the driver thereby to engage the support in its operative position and shift the support to its retracted position.  
  3. A stitcher head according to claim 1 further improved in that the sides ofthe driver bar have guide elements fitting grooves in the bender bar.  
  4. A stitcher head according to claim 3 further improved in that a gap is established between the opposed faces of the driver bar and driver.