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(11) | EP 1 440 897 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
Fabrication process for crimpable metallic crossbar terminals for flexible handles Herstellungsverfahren von Crimpbaren metallischen Querstänge für Trageschnüre Procédé de fabrication de barettes métalliques sertissables pour poignées flexibles |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] This invention generally concerns paper trade and bookbinding materials and articles and more specifically reinforced paper or plastic bags provided with flexible fabric or plastic handles, commonly of flexible cord, constituted for instance of sections of cord or plastic tubing whose extremities are provided with a crimpable crossbar terminal and respectively insertable through a pair of holes near the hem of the bag, by rotating the crossbar terminal in line with the cord and then releasing it to spread out from the cord once passing the hole, as needed to prevent it from slipping out.
[0002] For these uses, the crossbar terminals are commonly made of die-punched sheet metal, the sheet metal being suitable for readily and permanently crimping the handle cord or tubing.
[0003] The shape of the crossbar terminal thus obtained by die-punching is that of an elongated flat body with two lateral wings that are eventually bent perpendicular to the flat body of an elongated form. The joining or crimping of the crossbar terminal on the cord or other fabric suitable for handles occurs by folding the two wings over the handle's fabric material placed over the elongated body.
[0004] Normally, even this operation of applying crossbar terminals to the cord or fabric or equivalent plastic material is carried out by automatic machines, fed with the fabric strip or cord and with a continuous article of manufacture of die-punched crossbar terminals with wings bent at right angles to the elongated body, joined by severable metal bridging portions defmed by the die-punching tools, in order to keep together the crossbar terminals sequentially die-punched along a continuous strip of sheet metal incrementally fed to the punching machine.
[0005] While functionally effective, the crossbar terminals of this type have particularly undesirable drawbacks owing to their use in carrying bags to be filled with purchased articles, often items of apparel, footwear or the like.
[0006] The crossbar terminals of die-punched sheet metal retain relatively sharp cut edges, that may accidentally damage objects being inserted or extracted from the carrying bag, or scratch the hands.
[0007] "Hiding" the crossbar terminals in purposely created pockets or applying adhesives to cover them are expensive and/or time taking operations at any rate poorly effective solutions.
[0008] Moreover, malfunctionings are not infrequent due to a slipping out of the extremity of the handle cord or fabric strip from the crossbar terminal if subjected to just a slightly higher traction than normal.
[0009] EP-1 166 672-A1 discloses an end ferrule in the form of a semi-cylindrical body with rounded edges in the form of a 1/4 of a hollow sphere and two flaps that may be folded to crimp the end of the cord inside the semi-cylindrical body. The convexity of the ferrule effectively prevents accidental contacts with the sharp edges of the ferrule.
[0010] It has been found that though fabricating the crimpable sheet metal crossbar terminals for flexible fabric or plastic handles by die-punching a sheet metal, the drawbacks of the known process for fixing crossbar terminals are completely eliminated by forming the elongated or oblong shaped crossbar terminal body in the form of a tub by deep drawing the elongated body portion as obtained by die-stamping a strip of sheet metal. The drawing action is performed in a tub shaped mold using a corresponding pressing countermold and simultaneously also causes the bending of the two wings defined along the opposite sides of the flat die-stamped elongated body, thus preparing them to be eventually folded to crimp the fabric or plastic strip or cord, which is eventually pressed into the concavity of the tub formed elongated body.
[0011] The deflection of the fabric or plastic cord or strip inside the concavity of the drawn crossbar terminal and the interference that is thus created between the fabric or plastic handle and the hem at at least one extremity of the tub, considerably enhances the resistance to the slipping-out of the extremity of the fabric handle, crimped by the folded wings inside the concavity.
[0012] In use, the crimped crossbar terminal is pulled back in abutment with the inner surface of the hem of the bag by the weight of the bag suspended from the two flexible handles, as is disposes itself substantially cross-wire to the insertion hole of the bag hem.
[0013] The crossbar terminal thus offers its convex face to contact with the hands or the objects being introduced or extracted from the bag, preventing in practice any possibility of contact with the cut edges of the die-stamped sheet metal and of the severed sacrificial metal bridging portions, all laying in the plane of the face that is pulled against the inner surface of the (commonly reinforced) hem of the bag.
[0014] According to this invention, despite the drawing step that is contemplated in the new fabrication process of the crossbar terminals of this invention, they may be fabricated in the form of a continuous article of manufacture constituted by a chain of crossbar terminals defined by die-stamping and subsequently drawn in a mold, by retaining intact, even during the drawing step, the severable connecting metal bridges between juxtaposed extremities of the crossbar terminals adjacently formed along the sheet metal strip. As such, the continuous chain of formed crossbar terminals may be incrementally fed by normal automation techniques to the automatic machine that performs the crimping of the crossbar terminals on fabric or plastic handles, by folding the side wings to crimp the handle material pressed inside the oblong cavity of the tub formed crossbar terminal.
[0015] The various aspects and advantages of this invention will become even more evident through the following description of a few embodiments and by referring to the attached drawings, wherein:
Figures 1 and 2 show manufactured articles being produced in accordance with two different embodiments of this invention;
Figure 3 is an enlarged view of a tub formed crossbar terminal before fastening a flexible handle cord thereto by crimping;
Figure 4 shows a continuous article of manufacture consisting of a chain of tub formed crossbar terminals wound on a feed reel of a machine;
Figure 5 shows a handle made with sheet metal crossbar terminals made in the process of this invention;
Figures 6 and 7 show the manner in which flexible transport handles using the crossbar terminals made in the process of this invention are applied to a bag.
[0016] The Figure 1 shows crossbar terminals being fabricated according to this invention in the form of a continuous chain of crossbar terminals 1, joined by severable bridges 2, from a strip 3 of sheet metal.
[0017] The strip 3 is generally made of a thin sheet of mild steel, tinned or otherwise treated or coated to resist oxidation, although other relatively ductile alloys may also be used. The thickness and width of the strip 3 are commensurate with the dimensions and mechanical properties desired for the crossbar terminals to be produced. The thickness may generally be comprised between 0.2 and 0.5 mm, and the width between 7 and 16 mm.
[0018] In a first station of an automatic machine, flat bodies 1p of an elongated or oblong shape and having two lateral wings 4 and 5 are formed by die-punching. The flat bodies are stamped in sequence by incrementally advancing the feed strip 3 through the die-punching station, and remain attached to each other by narrow severable bridges 2, defined by the cutting perimeter of the die to connect the juxtaposed ends of two consecutively stamped bodies along he strip.
[0019] In a following station of the machine, the flat bodies 1p defined by die-punching are drawn in a tub shaped mold by pressing the sheet metal with a countermold or dolly. While drawing the crossbar terminal oblong body 1, the two lateral wings 4 and 5 orient themselves perpendicularly to the oblong or elongated body being drawn inside the mold.
[0020] The Figure 2 is a simplified view of an alternative embodiment of the two step process of fabrication of a chain of a crossbar terminals.
[0021] As can be observed by comparing Figures 1 and 2, the position of the two lateral wings 4 and 5 with respect to the length of the tub shaped elongated die-stamped and drawn body of the crossbar terminal 1 may be always the same (Figure 2) or alternately exchanged (Figure 1), depending on the feed requirements of the automatic crimping machine that fabricates the handles.
[0022] Moreover, while there may be only one, the drawing station after the die-stamping station thus contemplating the drawing of each flat body 1p that incrementally reach it, by pressing each flat body between a tub shaped mold and its dolly, causing a plastic deformation of the ductile sheet metal according to a sequential forming of each die-stamped body that reach the station as depicted in Figure 1, the machine may alternatively be provided with two or even more drawing stations, identically equipped, after the first die-punching station.
[0023] If for example two drawing stations are used, the drawing may not be performed on each die-punched body reaching the drawing station immediately following the die-punching station in the direction of advancement of the feed metal strip, but alternatively on either the odd or even numbered bodies, while in the following drawing station the drawing is performed on the even or odd numbered flat bodies that were not drawn upon passing through the first station. As depicted in Figure 2, at the outlet of the machine the manufactured article that is produced according to the sequential drawing scheme of Figure 2, will turn out to be essentially equivalent to the manufactured article produced according to the sequential drawing scheme of Figure 1.
[0024] An advantage of employing two or more drawing stations consists in providing for an enhanced freedom of plastic flowing of the sheet metal (induced by the drawing action), by permitting to a longer segment of the metal chain to contribute to the plastic flow of the metal in a longitudinal direction, thus limiting the concentration of strain in the bridging portions 2 that could lead to premature raptures.
[0025] The enlarged detail of Figure 3 shows a crossbar terminal according to this invention fully formed and ready to receive the cord or flexible textile or plastic strip to be crimped thereupon, by folding the two lateral wings inside the concavity in the form of an oblong tub of the drawn body I of the crossbar terminal.
[0026] Figure 4 shows an article of manufacture consisting of a chain of crossbar terminals made in the process of the invention wound on a feed reel of a handle-fabricating machine.
[0027] Figure 5 shows a textile handle, with metallic crossbar terminals 1 made according to this invention, crimped thereto, at the two extremities of a textile cord 6.
[0028] Figure 6 shows the way in which the handle is applied to the bag by passing each end of the cord 6, provided with the relative crossbar terminal 1, through a hole 7 present near the hem.
feeding a sheet metal ribbon to an automatic machine having a number of work stations;
defining by die-punching in a first station of the machine an uninterrupted sequence of flat oblong bodies having at least two coplanar lateral wings and severable sheet metal bridges joining the opposing ends of adjacently defined flat bodies, incrementally advancing said ribbon after every die-punching step;
deep drawing each of said die-punched flat oblong bodies in at least a second station of the machine equipped with a tub-shaped mold and cooperating pressing dolly, forming an oblong tub while simultaneously orienting said lateral wings extending from the respective straight side of the hem of the formed oblong tub, without severing said connecting sheet metal bridges.
Zuführen eines Blechbandes zu einem Automaten mit einer Anzahl von Arbeitsstationen;
Bilden in einer ersten Station des Automaten durchprägestanzen eine ununterbrochene Folge von flachen länglichen Körpern mit zumindest zwei koplanaren seitlichen Flügeln undmehreren Blechbrücken, die entgegengesetzte Enden von benachbarten flachen Körpern miteinander verbinden, und inkrementelles Fortschalten des Bandes nach jedem Prägestanzschritt;
Tiefziehen eines jeden prägegestanzten flachen länglichen Körpers in zumindest einer zweiten Station des Automaten, die mit einer trogförmigen Form und einem damit zusammenarbeitenden Pressstempel ausgerüstet ist und in der ein länglicher Trog geformt wird, während gleichzeitig die seitlichen, sich jeweils von einer entsprechenden graden Seite des Saumes des geformten länglichen Troges erstreckenden Flügel ausgerichtet werden, ohne die verbindenden Blechbrücken zu beschädigen.
fournir un ruban de feuille métallique à une machine automatique ayant plusieurs postes de travail ;
définir par poinçonnage au niveau d'un premier poste de la machine une séquence ininterrompue de corps oblongs et plats ayant au moins deux ailes latérales dans un même plan et des ponts en feuille métallique cassables reliant les extrémités opposées des corps plats définis de façon adjacente, en faisant avancer par incréments le ruban après chaque étape de poinçonnage ;
étirer profondément chacun des corps plats et oblongs poinçonnés au niveau d'au moins un second poste de la machine équipé d'un moule en forme de tube et presser de façon correspondante au vol, pour former un tube oblong tandis que l'on oriente simultanément les ailes latérales s'étendant à partir des côtés droits respectifs du bord du tube oblong formé sans casser les ponts de liaison en feuille métallique.