FR2558491A1 - TWO-WIRE SEWING MACHINE WITH PERFECTED BANDING ASSEMBLY, AND TWO-WIRE BONDING METHOD FOR CLOSING BAGS - Google Patents

Abstract

THE INVENTION RELATES TO A TWO-THREAD SEWING MACHINE 41, 102 AND A PERFECTED LOOP ASSEMBLY 52, 54, AS WELL AS A TWO-THREAD LOOPING PROCESS FOR CLOSING BAGS. THE LOOP ASSEMBLY INCLUDES A LOOP UNIT 54 INCLUDING A LOOP BLADE 88 WHICH TOGGLES IN AN ALTERNATIVE MOVEMENT ON A SINGLE ARC CONTAINED IN A SINGLE PLAN, ON A SINGLE SIDE OF A NEEDLE 40 ANIMATED BY AN ALTERNATIVE MOTION, THE PLAN CONTAINING THE TRAJECTORY OF A THREADED EYELET AT THE END OF THE LOOP BLADE 88 BEING PARALLEL WITH THE AXIS OF THE NEEDLE 40 AND CUTTING THE LINE OF MOVEMENT OF THE BAGS ACCORDING TO AN ANGLE LESS THAN 45, IN ORDER TO REDUCE WIRE WEAR AND BREAKAGE. APPLICATION TO THE EQUIPMENT OF INDUSTRIAL SEWING MACHINES, FIXED OR PORTABLE, FOR CLOSING BAGS BY TWO LINES OF SEWING.

Description

The present invention relates to the technical field of

  sew with two threads for closing bags,

  and the invention relates to a set of looping

  designed for two-thread type A sewing machines and a two-threaded fastening process. Sewing machines of the two-wire type carry a primary wire coil and a secondary wire coil,

  who respectively provide food for the eye of the

  guille with the primary wire and a claw chamber, located under the needle plate, with the secondary wire. This secondary wire is secured to the primary wire during the piqare to form the son of the chain by an interaction between a needle driven by a movement back and forth and a set of looping. In two-wire sewing machines, for closure of bags, which are known, the looping assembly uses a wire-carrying component of complex structure which generally follows several different and distinct mechanical movements. Typically, the component is difficult and expensive to manufacture, and it follows a complex trajectory comprising both tilting and thrusting motions in two or more than two intersecting planes, on two or more of two sides of the needle. Since such complex structural components and mechanical motions increase cost, require greater operating volume, and increase the probability of failure as well as the frequency of repairs, it is highly desirable to provide a two-wire loopback assembly that is configuration

  simple, easy to manufacture and uses a mechanical movement

  minimal and simple content contained in a single plane. None of the two-wire sewing machines for closure of previously known bags uses a looper that moves

  along a single arc contained in a single plane.

  Another disadvantage also of known two-wire sewing machines is that some of them use a looper that pushes through the needle path at an angle of approximately 90 to the direction of movement of the bags. This orientation of the looper may result in greater wear of the wire and more frequent breakage of the latter because the wire is first pulled normally in the direction of movement of the bags, and then it is brutally intercepted and pulled in a direction at right angles by

  relationship to the direction of the flow of bags.

  While it is desirable to provide a simplified and improved two-wire loopback device that can be used in both fixed and large, lightweight and portable sewing machines, it is particularly important to have structure and a simple and contoured movement for the looper of a portable two-wire machine, for which the weight and

  volume are still essential parameters. The inventors

  The invention is particularly well suited for use on portable sewing machines for closing bags of the general type shown in U.S. Patents Nos. 3,094,955 and 4,348,970.

  a portable, single-thread sewing machine for

  bags, having a looping blade which moves in a single plane, but which can be used to realize

  conventional seams, single thread.

  In recent years, the need for two-thread sewing machines to close sacks has increased due to the growing need to close sacks with double stitching and, in some cases, because of specific government regulations imposing such double seams. The present invention provides an improved loopback assembly, which is of simple structure and moves along a simple arc entirely contained in

  only one plane, on one side of the needle, in order to eliminate

  the complex structure and motion associated with two-wire loopback devices in the state of

technical.

  The invention relates to an improved looping assembly

  for a two-thread sewing machine, which is more economical, more reliable, and easier to manufacture than

  two-wire loopback devices currently available

  Nibles. the improved loopback assembly according to the invention uses a looping blade which tilts in an arc contained in a single plane and passes only on one side of the needle, using only the single reciprocating tilt movement described and avoiding complex trajectories, contained in several plans,

  I0 two-wire pusher of the state of the art.

  The improved looper cooperates with a needle plate which has a wire retainer notch in communication with an opening through the plate for receiving the needle. Primary and secondary wire loops are formed by the interaction between the looping blade, the notch and a spacer bar on the underside of the needle plate, to orient the wire loops of such so that they cut the trajectory of the needle, forming

  thus a chain of consistent and well knotted son.

  The looping blade comprises a vertical upright, an elongate arm extending cantilevered, and an eyelet at the free end of the arm. The intersection of the upright and the arm defines a hook that catches and holds the

  loop of primary wire during the sting.

  Unlike the modes of action of the prior art looper, according to the present invention, the looping blade moves in a plane which intersects the direction of movement of the bags with an angle less than 45, an angle between 10 and 20 being preferred. By avoiding the right angle orientation of the prior art slinkers, it is possible to reduce the wear of the wire and its

  breaks, and one can increase the reliability of the looper.

  By causing the looper arm to swing in a direction opposite to the direction of movement of the bags during insertion of a loop of secondary wire into the loop

  of primary thread carried by the needle, the amount of movement

  stitched bag can be used to tighten

different points.

  The invention also relates to a method of sewing a bag having the characteristic of the flat movement of the looper. Other features and advantages of the invention

  will be better understood by reading the description that

  FIG. 1 is a perspective view, partially exploded and partly in section, of a two-wire sewing machine for closing bags, FIG. FIG. 2 is a perspective view from below of the claw chamber of the machine shown in FIG. 1, and also showing the machine components in initial positions, FIG. Bottom view of the needle plate used in the machine of Figures 1 and 2, Figure 4 is a bottom elevational view of a portion of the needle plate of Figure 3, the view being taken in the direction of the sectional plane 4-4 of FIG. 3,

  Figure 5 is shown below.

  both the interaction of the needle and the looping blade of the machine of FIG. 1, during the stitching of a bag, FIG. 6 is a sectional view of a portion of the needle plate of FIG. taken in the direction of the sectional plane 6-6 of FIG. 3, FIG. 7 is another sectional view of a portion

  of the needle plate of Figure 3 taken in the direction

  7 is a perspective view from below of the claw chamber of the machine of FIG. 1, and represents the components of the machine in another functional state; FIG. Figure 9 is a perspective view from below of the claw chamber of the machine of Figure 1, and shows the machine components in another functional state, Figure 10 is a perspective view of the underside of the claw chamber. of the machine of FIG. 1, and still represents another functional state of the components of the machine, FIG. 11 is a perspective view from below of the claw chamber and also represents another functional state of the components of the machine, the Fig. 12 is a bottom view, on a larger scale, of some of the components of Fig. 11, and shows the interaction between the loop blade, the primary and secondary wires, and the needle plate, Fig. 13 is a Perspective view From below the claw chamber of the machine of Figure 1, and represents another functional state of the machine components, Figures 14 and 15 are enlarged bottom views of some of the components in the chamber. claw, and it represents the interaction of

  components during the puncture, during two successive states

  Fig. 16 is a side sectional view of the needle and the loop block, the cut taken in the direction of the section plane 1616 of Fig. 5, Fig. 17 is a side view of the loop block. ,

  the view being taken in the direction of the section plane 17-

  17 of FIG. 16, FIG. 18 is a partial top view of the end of the looping blade, the view being taken in the direction of the sectional plane 18-18 of FIG. 17; FIG. in section from the top of

  the looping blade and the clawblock, the cut represented

  both the trajectory of the secondary wire and the positions

  extremes of all the positions taken by the blade of

  during operation, this view being taken in the direction of the section plane 19-19 of Fig. 18, Fig. 20 is a side sectional view taken through the arm of the looping blade in the direction of the section plane. 20-20 of Figure 18, and Figure 21 shows an alternative embodiment of a coupling blade usable in the context of the invention. Referring now to FIG. 1, a portable two-wire sewing machine 10 for closing bags made in accordance with the invention has a rigid and protective housing 20 and carries supports 12 and 14 of the coils, which are fixed to the machine by screws 15 screwed into the housing, these supports

  retaining coils 16 and 18 which respectively constitute

  sources of primary and secondary wires.

  The bag closure machine 10 comprises a carrying handle 22 and a motor 24 fixed to the casing 20, the

  engine being powered by a power cord in power-

  26, and this machine also includes an

  hand-operated (not shown), arranged on the

handle.

  The electric motor 24 has a pulley 25 attached to the upper end of its shaft, and a V-shaped belt 28 surrounds the motor pulley 25 and extends to a second pulley 30, which is attached to the upper end. of the main drive shaft 32 of the sewing machine. The main drive shaft 32 is rotatably mounted in the housing 20, with a generally vertical orientation. The motor 24, the pulleys 25 and 30, the belt 28 and the rotatably mounted drive shaft 32 are suitably mounted relative to one another and relative to the housing to form, together, a control device. A drive for use within the scope of the invention for operating the components of the machine 10. Although the specific training device described herein is preferred, it must be well

  that other types of engines and train

  may be substituted for it, if desired,

  and such variations are within the scope of the invention.

  The shaft 32 carries an eccentric 34 drive

  needle which is connected to the drive lever 36 of

  guille, the lever 36 being connected to other known parts which extend downwards into the housing and drive the shaft 38 driving the needle reciprocating back and forth. The eccentric 34, the lever 36, the needle shaft 38 and the needle 40, as well as other known intermediate portions together constitute a needle drive assembly for moving the needle 40 along the length of the needle. a trajectory 42, in order to pierce a bag during the puncture. Since the structure of the needle drive assembly shown is well known in this technical field and fully described in US Pat. No. 4,348,970, it will not be further described. However, it should be understood that the specific needle drive assembly, described herein, is intended merely to illustrate a type of needle drive assembly that can be used in the context of the present invention, and that other mechanical arrangements suitable for driving the needle reciprocally along the trajectory 42 may be substituted for it and fall within the scope

of the present invention.

  A primary wire 41, coming from the coil 16, passes through the guides 43 and 45, and finally reaches the eye.

  47 (Figure 2) of the needle 40, in which it passes.

  The lower end of the drive shaft 32 includes an eccentric and offset claw cam 56, which is rotatably mounted in a claw block 76 (FIG.

  8, and 10), so that the rotation of the drive shaft

  32 in the direction 31 moves the claw 78 on a trajectory

  substantially circular groove centered on the shaft 32, to advance the bag downstream 80 as will be described more

precisely below.

  At the drive shaft 32 is fixed a looping cam 44 in the lower surface of which is

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  formed an eccentric channel 46, which houses a cam follower 48 extending into and following the channel 46 during the rotation of the cam 44. The follower 48 extends upwardly from a follower arm 50 which is attached to a looper drive shaft 52, rotatably mounted, and having

a central and longitudinal axis 53.

  The looper shaft 52 extends downwardly at an angle of approximately 14.50 to the vertical, and passes into bearings which are not shown in the drawings for simplification purposes, and at its lower end. he is wearing a loopback unit 54

  which will be described in more detail below.

  When the main drive shaft 32 rotates about its central axis in the direction 31, the loop cam 44 rotates with it and drives the follower arm 50 in a reciprocating tilt movement over an arc of about 28 to make rotate the looper shaft 52 and

  to operate the loopback unit 54.

  Referring next to FIG. 2, the housing 20 comprises a claw chamber 58 in which the looper drive shaft 52 and the main drive shaft 32 extend, and in which the looping action of the sewing machine. Open bottom

  chamber 58 is clipped during operation.

  by a detachable cover plate 60, which is fixed by screws 62 screwed into holes 63 in the wall of the chamber. The claw chamber has an opening 64 in its side wall and is covered by a needle plate 66, generally flat, slightly

  folded, interacting and cooperating

  aunt with the loopback unit 54, as will be described below. A third cover plate 35 is fixed

  to the housing under the needle shaft 38 by screws 37.

  A well-known conventional press foot assembly is mounted in the housing and includes a shaft 68 which is biased toward the needle plate 66 by a spring 70, and which carries a presser foot 72 (FIG. a bag passing and cooperates with the claw 78 to tighten the bag between the latter and the foot

pressing 72 during sewing.

  Referring now to Figures 1 and 2, a claw assembly 74, usable in the context of the invention, is rotatably mounted in the claw chamber 58 to be rotated on a small circular centered path. on the longitudinal and central axis of the shaft 32, such rotation being effected in response to rotation of the eccentric claw cam 56 which is rotatably mounted in a bearing aperture in the claw block 76. claw 78 has teeth 79 (Fig. 9) extending outwardly from the claw chamber and passing through slots 82 and 84 in the needle plate 66. Although several sliding bars are used with the block with claw to guide it during its circular movement, such guide bars are known in this technical field but omitted from the drawings to simplify the views and to allow better visibility of the whole looper decribed t below. The claw assembly 74 includes the block 76, the claw 78 attached thereto, and which cooperates with the presser foot 72, and the associated sliding bars which carry the claw and support it within

  room 58. A more detailed description of the ensemble

  The claw assembly shown is preferred for use in the present invention, other suitable claw assemblies may be substituted therefor in accordance with US Pat. No. 4,348,970. variant and are part of the

present invention.

  Referring now to Figures 1, 2 and 12, the lower end of the looper drive shaft 52 carries a loopback unit 54 which includes a loopback block 86 and a removable and replaceable loopback blade 88. The block 86 is forked and forms a sleeve 87 which houses the looper shaft 52. A screw 89 with hexagon socket tightens the parts of the fork on the shaft 52 to

  to firmly lock the block on the shaft in a direction

predetermined angular

  As is clearly shown in FIGS. 5, 12 and 18 to 20, the looping blade 88 comprises a rigid upright 92, rectilinear and vertical, having a central axis 94, and an elongated and thin arm 96, extending as a door at right angles and outwardly, relative to the amount 92. The axis 94 of the upright and the end arm 96 which cut it define a plane which is oriented substantially perpendicularly to the shaft 52. A looping eyelet

  , which carries a loop of secondary wire 102, is adjacent to

  100 at the free end 98 of the arm. The end faces 104 and opposite 106 of the arm 96 of the blade are substantially flat with a beveled edge 97 at the end 98 to facilitate the best passage of the arm 96 of the blade in position immediately adjacent to the needle 40, when

  the blade moves along its trajectory 107. We have

  that the length of the arm 96, measured from its intersection with the amount 92, is the most effective if it is approximately equal to four times the diameter of the needle 40. The arm can be slightly longer, however, while remaining effective. The arm 96 and the amount 92 define, at their intersection, a hook 182 intended to come into contact with the loop 172 of the primary wire, during the looping operation. When the shaft 52 pivots on the arc A, the amount 92 and the looping blade

  88 swing over the arc A from an approximate center angle

  28, between positions 192 and 194 (figures

  12 and 19), during their displacement the lông of the trajec-

  107 of the blade. The trajectory 107 that follows the blade 88 is an arc that immediately passes close to the trajectory 150 of the needle. It should be noted that the looping blade moves in a plane 200 (FIG. 17) which is delimited by the envelope of the positions of the loop eyelet 100 along the path 107, as shown in FIG. This plane is immediately adjacent to the trajectory 105 of the needle, and it is fixed with respect to the trajectory of the needle and parallel to the trajectory 150. The lower end of the post 92 has a flat surface 101 and is received in a sleeve 108 of the upper end of the loop block 86, the amount being retained and fixed in the sleeve 108 - by a screw 110 with hexagon socket resting against the surface 101. As shown in Figure 5a, the planar surface 101 is oriented at 5 from the angle at which the arm 96 extends from the upright 92 so as to facilitate the positioning of the upright in the socket 108, so that the arm 96 is in the immediate vicinity of the needle 40. The arm 96 feel a passage 210 of the wire slot, which extends from the eyelet 100 to the end 212 of the arm, to accommodate the secondary wire 102, as will be described in more detail below. The slot 210

  of the blade 88 is inclined at 5 with respect to the lower edge

  arm 214, to align the wire more easily

  102 with a tunnel 120 formed in the claw block.

  The secondary yarn 102, which is carried by the loop eyelet 100, comes from the spool 18 of secondary yarn, and its free end 103 extends outwardly from the claw chamber through the opening 112 to the claw chamber 58, the secondary wire extends from the spool 18 through the housing 20 along a guide passage 114 (FIG. 1). The wire 102 leaves the guide passage 114 to then surround the wire guide 116, after which it extends into the channel 118 to the claw chamber 58. As shown in FIGS. 2 and 19, the wire secondary 102, after entering the claw chamber 58, passes through a tunnel formed in the claw block, and leaves the latter to then extend into the slot 210 for passage of the wire and in the loop eyelet 100 of the blade 88. The

  tunnel 120 is drilled and oriented in a portion 216 extends

  forward direction of the claw block so that the axis of the tunnel is substantially aligned with the direction of the elongated and cantilever arm 96 to thereby minimize friction and drag between the block claw and the arm 96, during a relative movement between the claw and the arm, but the tunnel 120 is positioned towards the front of the arm 96, as shown in FIG. 19, so that the drag imposed on the wire 102 by the guide 116 recalls the wire 102 in the slot 210 for passage of the wire and holds it in this slot during the puncture. It follows from the use of the slot 210 that the wire 102, which extends along the arm 96, is forced to remain in

  the plane 200, in which the looper moves. The extremes

  mites 218 and 220 of the slot 210 are rounded to

  reduce the friction between the slot and the wire.

  An alternative embodiment 230 of a looping blade that can be used in the context of the invention is shown in FIG. 21. The blade 230 is identical to the blade 88 of the preceding figures except that the angle between the upright 92 and the edge lower 214 of the arm 96 is-850, and that

  the slot 210 for the passage of the wire is inclined by 5 to

  214. According to an advantageous characteristic, looping blades having angles of between 80.degree.

  and 1000 between the amount 92 and the edge 214 of the function arm

  in the machine 10, but the best

  their results are obtained when the angle is between 85 and 90. The operation of the blades 88 and 230 is

  substantially identical and will be described below.

  Referring now to Figures 3 to 5, the needle plate 66 has inner and outer surfaces 126, 126 screw holes 126 passing through the needle plate to receive screws (not shown) for securing it. to the casing. The plate 66 has a

  pair of slits 82 and 84, elongated and substantially parallel

  the, which receive the teeth 79 of the claw 78 and allow the teeth to extend outwardly through the slots in order to engage against a bag and cooperate with the presser foot 72 so as to tighten the bag and move it past the needle. An elongated segment 128, integral with the plate 66, is positioned between the slots 82 and 84 and extends towards the avald'une a sail 130 to a web 132, the gxet 128 has an opening 112 for passage of the needle, which opens on surfaces 122 and 124,

  and wherein the needle 40 moves during the puncture.

  On the downstream side of the opening 112 is a thread retention notch 134, which is formed in a cross-bar

  136 extending transversely across the segment 128.

  As will be described in more detail below, the wire retention notch 134 engages with the blade 88 to position the secondary wire and provide it with a predetermined orientation suitable for piqfire and loopback. The lower surface 124 of the needle plate

  66 has a plurality of reinforcing ribs 141 extending

  transversely and stiffen the plate.

  A ramp-like spreader bar 138 is positioned on the lower surface 124 of the segment 128, upstream of the needle opening 112, and this bar extends outwardly from the surface 124, cooperating with the looping blade 88 to orient the secondary wire loop 178 to facilitate the insertion of the needle 40 moving downwardly in the loop 178 of the secondary wire, as this

will be described below.

  In operation, the user of the machine

  sewing starts by threading the primary 41 and second

  102 along the appropriate thread guides to the eye 47 of the needle and up to the loop eyelet 100, respectively, passing the threads through the eye and into the eyelet. With the needle occupying the raised position 140, shown in FIG. 2, a bag is introduced into the gap between the needle plate 66 and the entry guide 142 raised by the presser foot 72.

  simplify the following description of how

  the machine, the primary wire 41 associated with the needle 40 is

  represented as being completely blackened, and the secondary wire

  102 associated with the loopback unit 54 is shown

without shadow.

  In the configuration of the beginning of operation, shown in Figure 2, the claw 78 is substantially in its outermost position, in which its teeth 79 protrude beyond the needle plate 66, the teeth passing through the slots 82 and 84 so as to contact a bag and apply it against the presser foot 72. In the outermost position of the claw teeth, shown in FIG. 2, the teeth of the claw disengage the presser foot 72 of the needle plate 66 over a distance of approximately 1.5 mm or more. In response to the rotation of the main drive shaft 32, the claw 78 moves according to

  a substantially circular trajectory in an anti-

  when viewed from below the machine looking upwardly along the axis of the drive shaft 32. During the movement of the claw along its path, it advances the bag on the machine in the direction of travel 80 and then tilts down in the direction of travel 144 in the claw chamber 58, after which it moves upwards in the direction of movement 146 to advance the bag for the

next point.

  When the needle 40 is in its raised position (FIG. 2), before the entrance of the bag, the looping unit 54 is in the position 148 in which the looping blade 88 is oriented so that its free end or end 98 be positioned completely to the right when

we look at Figure 2.

  To put the machine into operation, the operator pushes a push-button switch mounted on the handle 22 (FIG. 1) and the motor 24 begins rotating the pulley 26 to transmit rotational movement through the belt 28 to the main drive shaft 32. The rotation of the shaft 32 in

  the direction of rotation 31 actuates the different sub-

  sets of the machine, including the trainer set 36

  of the needle, which causes the needle 40 to move downward from position 140 (FIGS. 2 and 5) along a straight line path 150 clearly defined along the axis of the needle. When the main drive shaft 32 is rotated, it drives the buckling cam 44 (FIG. 1) which is fixed to it, by driving the follower arm 50 reciprocating about an arc of approximately 28, when the arm follows the channel 46. This movement repeatedly switches the loopback unit 54 in a motion

  equivalent which will be described in more detail below.

  below. The rotation of the main drive shaft 32 also rotates the claw cam 56 which is

  secured, by actuating the claw block and entering it:

  on its circular trajectory to advance a bag

on the machine 10.

  In the following description of the operation, made

  with reference to Figures 2 to 16, the movement of the various machine components will be described as up, down, left and right. These

  terms are used in relation to the orientation of the

  which is shown in the figures. However, it should be understood that when the machine 10 is in commercial use, it is particularly intended to be implemented having the orientation shown in Figure 1. Accordingly, in most figures,

  the agreements relating to the directions described correspond to

  lay to the directions as viewed by an observer looking substantially upward in the

  chamber 58 to claw of Figure 1.

  Referring now to FIG. 8, when a bag 152 moves downstream 80 to enter the machine 10, the bag is taken by the claw 78 which advances the bag a predetermined distance in the direction 80, downstream, beyond the needle 40. Having reached the leftmost position 154, * the claw, as shown in FIG. 8, swings downwards in the direction 39, piercing the bag 152 and passing through the aperture 112 provided for the needle in the needle plate, in order to enter the chamber & claw 58, and carrying with it the primary thread 41. During the downward descent of the needle 40 from the raised starting position 140 (FIG. 2), the looping unit 54 switches to the left in the direction 158 to the position shown in FIG. 8, when the stenter moves from the position 2, to that of FIG. 8, the secondary wire 102 comprises a segment of wire 160, (well shown in Figure 12) which constitutes a part of the loop 166 of secondary wire and which extends between the loop eyelet

  10Q and the thread retention notch 134, the upper end

  upper wire 102 being pinched between the presser foot 72 and the needle plate 66. When the unit

  loop 54 toggles left from the position

  2 to the position shown in Fig. 8, the small portion of the secondary wire segment between the retaining notch 134 and the loop eyelet 100 is slightly relaxed, so that be solicited to the outside. towards the

  reader when he considers figures 8 and 12.

  This outward movement causes the wire segment 160 to be just clear of the path 150 of the needle, as shown in FIG. 8, to allow the tip 164 of the needle 40 to begin to pass into the segment. 160, when the needle moves downward in the direction 39. During the downward movement of the needle through the bag 152, the claw 78 is

  clear of the bag and do not move it.

  Referring now to FIG. 9, the needle continues its descent so that its tip 164 engages more in the secondary loop 166. When the needle

  moves downward in loop 166 to its position

  At the lowest level 170, the loopback unit 54 continues to swing to the left in the direction 158, about the axis of the looper shaft 52. When the loopback blade 88 moves to the left, as shown in Figure 9, the secondary wire 102 slides along the slot 210 for receiving the wire and passes through the loop eyelet, being fed from the tunnel 120 which passes through the portion 216 of the claw. When the needle 40 is in its lowest position 170, the claw 78 has its teeth 79 in a position 174 well below the upper surface of the needle plate 66, and it moves to the right and to the right. the top, in the direction 159, to a position in which the teeth 79 can finally come into contact with the bag 152 and move it in the direction 80 for the next point of the needle. In Figure 9, the looper is shown in its leftmost position 168 and then it switches to the right towards

the needle 40.

  During the operation of the machine 10, the secondary wire is fed to the looping blade 88 from the tunnel 120 formed in the part 216 of the claw. As shown in Fig. 19, the secondary wire 102 forms an acute angle as it leaves the tunnel 120 and advances toward the blade 88. This particular change of direction recalls the wire 102 in the wire passage slot 210 so as to tightly confine the secondary wire and direct it towards the looping eyelet, keeping the wire substantially in the plane 200. The tilting movement of the buckler between the positions 192 and 194, as well as the claw block 76 movable exert a tensile force on the secondary wire 102 in order to overcome the drag developed by the intermediate guide means 43 and 116. It results from this combination a close cooperation between the guides, which develop a sufficient drag to keep the wire 102 biased against the wall of the slot 210 for the passage of the wire, and the

  own movements of the blade 88 and the block 76, which overcomes

  smoothly drag and facilitate movement

  from thread 102 to loop eyelet 100. Such cooperation

  This arrangement reduces the likelihood of breakage and abrasive wear of the yarn, since yarn 102 is drawn into the machine by a primary interaction between dies 79 of the claw and bag 152. Referring now to the figures 5 and 10, the loopback unit has tilted further to the right, in the direction 171, moving towards the needle 40 and passing therethrough. As the tip 98 of the blade moves toward the needle, the needle moves upward, thereby causing the primary thread loop 172 to extend laterally and rearwardly from the needle. and allowing the end 98 of the looping blade 88 to easily penetrate into the extended primary loop 172 as the blade passes the back of the loop.

  the needle and moves further to the right of the needle.

  guille, as shown in FIGS. 10. When the loopback unit 54 tilts in the primary thread loop 172, the claw 78 has moved from the position 174 to its rightmost position 176, and it moves upward toward the needle plate 66. Referring now to FIGS. 11 and 12, the loopback unit 54 is shown to have swung to the right in the direction 171 to its fully rightward initial position 148. During such a movement, the end 98 of the looping blade 88 has moved entirely into the primary loop 172 and has introduced the secondary loop 166 into the primary loop 172. During the movement of the looping blade 88 to its extreme right position 148 , the primary loop 172 has been pulled to the left in the direction 80, in the hook 182. The loop of primary wire 172 is pulled in its position in the hook 182 by the movement of the claw 78 which comes into contact with the bag 152 and moves the latter, on the equel the primary wire 41 is attached, in the direction 80. During the time interval during which the primary loop 172 and secondary 166

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  are in the orientation shown in Fig. 12, the primary loop 172 closely encloses the wire segment

  in point 184 and retains segment 160 where that

  nio eat Rappela against the side of the spreader bar 138. The game created between the looping blade 88 and. the wire segment 160, due to the interaction between the loopback eyelet 100 of the arm 96, the spacer bar 138 and the tightening effect of the tight primary loop, considered collectively, form a suitable game for the passage of the needle 40 between the secondary segment and the arm 96, when the looping blade begins to swing to the left, as will be described below

  with reference to Figures 13 and 14.

  Referring again to FIG. 12, the wire retention notch 134 receives the secondary wire 102 and the primary wire loop 172 in the notch 134 when the claw moves the bag in the direction 80, thus ensuring that the primary loop 172 is kept clear of the trajectory 150 of the needle during the downward movement thereof, and the secondary thread 102 remains in the configuration shown in FIG.

  the needle 40 moves downward in the loop 166.

  All the secondary wire 102 required and required by the looping blade 88, is obtained from the wire spool 18 by the movement of the looper, pulling the wire 102 into different guides and out of the tunnel 120 into the block claw. By causing the looping blade 88 to move in a direction substantially aligned with the tunnel axis 120, and causing the path of the loopback blade to be substantially aligned with the direction of travel 80 of the bags, the thread 102 can be pulled smoothly by the looper and with minimal frictional wear or with minimal breaks in the secondary thread. Such a movement of the looper along a path 107 (FIG. 12) such that the plane 200, defined by the trajectory, intersects the direction of movement of the bags at an angle which does not exceed 45, reduced

  to a large extent the wear and tear of the secondary wire.

  say by comparison with loops that move at right angles to the direction of movement of the aAcs. But again, when the angle does not exceed 204, the operation is improved, and the best results

  are obtained when the angle is between 10 and 20.

  The arrangement shown, in which the free end of the arm 96 swings upstream, in a substantially

  opposite to the direction 80 during the insertion of the sec-

  120, also improves the operation through the use of

  lisation of the momentum of the bags to tighten

the points that are formed.

  Referring again to FIGS. 11 and 12, when the loopback unit 54 reaches the position 180, the needle 40 is substantially in its upper position 140, the loopback unit 54 reaches its rightmost limit, and the claw 78 has contacted the bag 152 and is moving in the direction 80 to slide the bag a distance equal to the spacing between points

add on the bag. -

  Referring next to FIGS. 13 and 14, in the course of the subsequent operation, the needle 40 moves downward towards the needle plate 66 while the claw 78 swings to the left and down in the sense 186 in order to clear the teeth of the claw

  of the bag 152 before the entry of the needle 40 into the bag.

  The needle 40 continues to descend, passing through the bag and the needle plate-66, down to

  a position 196 in the claw chamber 58, as shown in FIG.

  13. When the tip 164 of the needle approaches the wrap arm 96, the loopback unit swings left in the direction 188, thereby causing the secondary wire segment 166 to expand. slightly laterally and outwards, towards the reader when the latter considers FIGS. 12 and 13, in order to form an additional clearance from the trajectory of the needle, while the needle 40 moves downwards and passes between the segment 166 and the looping arm 96, to obtain that the secondary loop 166 encircles

  the needle, as shown in Figures 13 and 14.

  When the looping blade moves in the direction 188 to the position 190 (FIG. 13), the primary loop 172 slides towards the end 98 of the looping blade and

  disengages from the blade by coming on the loop of wire-secon-

  166, as shown in FIG.

  When the loopback unit 54 continues to swing to the left, in the direction 188, it pulls the secondary wire loop 166 and begins to tighten it, as shown

  in FIG. 15. Simultaneously with such a tightening, the movement

  Downward movement of the needle 40 in the direction 39 pulls the primary wire 41, which extends to the primary loop 172, in order to shorten and thus tighten the primary loop 172 around the secondary loop 102 and help to form the sting point. After the formation of the dot, as shown in Fig. 15, the needle 40 moves upward while the loopback unit 54 returns from its leftmost position 168 and tilts in the primary thread loop 172 by against it, as shown in Figs. 5 and 10. The loopback unit 54 then continues to swing to the right in the direction 171, as shown in Fig. 12, while the needle 40 moves to the top and comes off the bag, and that the

  primary wire loop 172 is pushed back into hook 182.

  When the needle is released from the bag, the claw 78 has

  positioned itself in order to come into contact with the bag and move it to the left for the next stitching point. When the bag is moved in the direction 80 by the

  cooperation of the claw 78 and the presser foot 72, the movement

  the bag further draws the point 172 being tightened and shown in FIG. 15, so that

  point tightly against the bottom of the bag 152.

  The method of forming stitches then continues as described in connection with the figures,

  by continuing and repeating the steps described in

FIGS. 13 to 15.

  The embodiment variant 230 of the looping loop

  shown in Figure 21 can be directly substituted

  in the embodiment 88 shown in FIGS. 1 to 20. The operation of the two embodiments

is identical.

  Of course, various modifications can be made by those skilled in the art to the devices and methods which have just been described as examples only.

  non-limiting without departing from the scope of the invention.

Claims (24)

  A sewing machine, of two-wire type, for closing bags, for sewing a bag (152) closed when the bag moves downstream (80) in the machine (10), said machine comprising: a rigid housing (20) comprising a claw chamber (58), driving means (24, 25, 28, 30, 32) carried by said housing (20), -   primary and secondary sources of wire (16, 18) adjacent to said housing (20) for feeding primary wire (41) and secondary wire, respectively (102)   a training set (34,36,38) of a needle   (40), movably mounted relative to said housing (20),   connected to said drive means (24, 25,.   28, 30, 32), and comprising a needle (40) animated by a   reciprocating and movable movement along a path   needle (150) for entering and exiting said claw chamber (58), said needle (40) having an eye (47), said eye (47) carrying a loop (172) of said primary wire (41), a presser foot assembly (68,70,72), adjacent to the needle (40) and carried by said housing (20) to engage the bag (152), a claw assembly (74) carried by said housing (20), operatively connected to said drive means (24,, 28, 30, 32), and having a movable claw (78), reciprocated, and facing the bag (152), said claw cooperating with said presser foot assembly   (72) to advance the bag (152) downstream (80) to   beyond the reciprocating needle (40), during the puncture of the bag (152), a needle plate (66), adjacent said claw (78), said plate (66) having an opening (112) ) passing the needle (40) in communication with said claw chamber (58) and positioned along said path (150) of the needle (40) to receive said needle (40) during the puncture, characterized in that it further comprises a loopback assembly comprising: a looper drive shaft (52), having a central axis (53), movably mounted relative to said housing (20) and operatively connected (44, 46, 48, 50) to said means   (24,25,26,28,30,32) in order to alternate between   pivoting said shaft (52) about an arc about said central axis (53) of the shaft (52), and   a buckling unit (54) attached to said buckler shaft   (52) and comprising a looping blade (88) presenting   an eyelet (100) carrying a loop (166) of said secondary wire (102), said tilting looping blade (88)   in a position immediately adjacent to the said trajec-   the needle (40) in response to pivoting of said looper shaft (52), so that the envelope of the positions of said looping eyelet (100) defines a plane (200) which is fixed relative to said path (150) of the needle (40), whereby said blade (88) hooks said primary wire loop (172) (41) and inserts said secondary wire loop (102) into said loop (172) of primary wire (41).   2. Sewing machine according to claim 1, characterized   characterized in that said plane (200) defined by said arc is parallel to said path (150) of said needle (40).   3. Sewing machine according to claim 1, characterized   characterized in that said needle plate (66) further has a wire-retaining notch (134) communicating with said needle-passage opening (112) and extending toward the downstream from said opening (112), said notch (134.) cooperating with said looping blade (88) to receive and stretch between them a segment (160) of said secondary wire (102), in order to retain said loop (166) of secondary yarn (102) across the path (150) of said needle (40) during downward movement thereof, and for confining said segment (160) in said notch (134) while said needle (40) moves said primary wire (41) in said secondary wire loop (166) during the downward movement of said needle (40).   4. Sewing machine according to claim 3,   characterized in that said needle plate (66) further comprises a spacer bar (138) upstream of said needle (40), and adapted to cooperate with said looping blade (88) to form said loop (166) secondary   contacting said second wire segment (160)   (102) and away from said path (150) of the needle (40) to provide clearance sufficient to allow said needle (40) to enter said loop. secondary (166).   The sewing machine according to claim 1, characterized in that said looping blade (88) comprises a hook (182) intended to come into contact with said primary wire loop (41) and such. said hook (182) is positioned downstream of said path (150) of the needle (40) when said needle (40) passes at said looping unit (54) during the descent of the needle (40).   Sewing machine according to claim 5, characterized   characterized in that said loop eyelet (100) is positioned upstream of said path (150) of the needle (40) when said needle (40) passes at said loopback unit (54) during descent of the 'needle.   Sewing machine according to claim 1, characterized   characterized in that said buckling unit (54) comprises a buckling block (86) attached to said looper shaft (52) for rotationally integral therewith, and said blade (88) comprises a post rigid (92) retained on said block (86), said blade (88) further comprising an elongated arm (96) extending outwardly and cantilevered from said post (92), said blade having said looping eyelet (100) at the free end (98) of said arm (96), said post (92) and said   arm (96) forming said hook (182) at their intersection.   Sewing machine according to claim 7, characterized   characterized in that said post (92) is substantially flat and has a central axis (94) of the post, and said arm (96) is substantially straight and thin,   said axis (94) of the upright and said thin arm (96) extends   substantially in said plane (200).   9. Sewing machine according to claim 7,   characterized in that said arm (96) and said axis (94) of the   both (92) cuts substantially at right angles.   10. Sewing machine according to claim 7,   characterized in that said arm (96) extends from said post (92) a distance of at least four times   the diameter of said needle (40).   11. Sewing machine according to claim 7,   characterized in that said arm (96) extends from said post (92) a distance substantially equal to four   the diameter of said needle (40).   Sewing machine according to claim 7, characterized   characterized in that said arm (96) and said axis (94) of the upright (92) intersect at an angle of between 80 and 100.   13. Sewing machine according to claim 7,   characterized in that said arm (96) and said axis (94) of the upright (92) intersect at a substantially equal angle at 85.   Sewing machine according to claim 7,   characterized in that said arm (96) has an end   mite (212) adjacent to said post (92), and in that said arm (96) further has a wire passage slot (210) extending from said eyelet (100) to said adjacent end (212) audit amount (92), to house and guide   said secondary wire (102) to said eyelet (100).   The sewing machine according to claim 14, characterized in that: said claw assembly (74) comprises a claw block (76) having a portion extending forwardly relative to   said looping blade (88), said portion being traversed by   S4é by a tunnel (120), said secondary wire (102) passes into said tunnel (120) and extends from said tunnel (120) rearwardly to said slot (210) for passage of the wire formed in said looping blade (88), and it circulates along said slot (210) until said looping eyelet (100) in which the secondary wire (102) passes, guide means (114,116,118) of the wire are mounted on said housing (20) between said source (18) of secondary wire (102) and said claw block (76) for dragging said secondary wire (102) to maintain said secondary wire extending between said   tunnel (120) and said wire guide slot (210),   against said slot (210), so as to retain said secondary wire (102) in said slot (210) and substantially in said plane (200), during operation, and the reciprocating movement of said claw (78), during advance of the bag (152) causes relative movement of said tunnel (120) relative to said guide means (114, 116, 118) to assist in overcoming said drag and thereby assisting said looping blade (88) in its pulling action on the secondary wire (102) from said source (18) of secondary wire.   16. A two-thread loop method for sewing downstream bags (152) in a sewing machine (10) of two-thread type and for closing bags, said machine having a foot presser (72), a claw (78), primary (41) and secondary (102) wires, and a pivoting loop (54) having a blade (88), a loop eyelet (100) adjacent to one end (98)   of the blade (88) and carrying a loop (166) of secondary wire   (102), an angular hook (182) formed on said blade (88) and spaced from said eyelet (100), and a needle (40) reciprocating and having a needle eye (47) in which a loop (172) of primary wire (41) is carried, the needle (40) moving along a path (150) and passing through the foot pxea * 1 (72), said method being characterized by it comprises the steps of: moving the needle (40) and the primary wire (41) carried by the eye (47) of the needle through said bag (52) and a needle plate ( 66) to introduce the primary wire loop (172) under the throat plate (66), tilt the elongate blade (88) of the loopback unit (54) in a first direction along the an arc extending substantially in a plane (200) and adjacent to the needle path (150) from a first position clear of the needle path to a second position in wherein the blade (88) passes through the loop (172) of the primary wire (41) carried by the needle (40) to form and introduce the secondary wire loop (166) into the loop (172). ) of primary wire (41) and to cause the primary wire loop (172) to slide in a direction opposite to the first direction and against the hook (182) to move the needle (40) upwards, along the path (150) of the needle to remove it from the needle plate (66) and bag (152),   move the claw (78) downstream, beyond   the needle (40) to cooperate with the presser foot (72) to advance the bag (152) downstream (80) for the next stitch point, move the needle (40) down through the bag (152) and along the path (150) of the needle, into the loop (166) of secondary wire (102) to retain the secondary loop (166) while the looping blade (88) tilts the second position to the first position while the claw (78) continues to move the bag (152) downstream (80) to thereby pull the loop (172) of primary wire (41) and tighten it around the secondary loop (166), and   move the needle (40) upwards in a position   open the bag (152) and bring back the looping blade (88) in its first position.   17. A sewing machine of two-wire type for closing bags, for sewing a bag (152) closed while the bag is moving downstream (80) in said machine (10), said machine comprising : a rigid housing (20) having a claw chamber (58)   drive means (24,25,28,30,32) carried by said housing (20), primary and secondary sources (16,18) of wire, adjacent to said housing (20) to provide power   primary yarn (41) and secondary yarn (102), respectively   an assembly (34,36,38) for driving a needle (40), said assembly being movably mounted relative to said housing (20), operably connected to said drive means (24,25,28,30 , 32), and comprising a reciprocating needle (40) movable along a path (150) to enter and exit said claw chamber (58), said needle (40) having an eye (47) in which a loop (172) of said primary wire (41) is carried, a presser foot assembly (68,70,72) adjacent said needle (40) and carried by said housing (20) to resting against the bag (152), a claw assembly (74) movably mounted relative to said housing (20), operatively connected to said drive means (24,25,28,30,32), and having a claw (78) movable and reciprocated, facing the bag (152), and cooperating with said presser foot assembly (72) to advance the bag (152) downstream (80), at the beyond the treble the needle (40) reciprocates while sewing the bag (152), a needle plate (66) adjacent said claw (78) and having an opening (112) for passage of the needle, in communication with said claw chamber (58) and positioned along said path (150) of the needle (40) to accommodate said needle (40) during sewing, characterized in that it further comprises a looping assembly improved, functionally connected (44,46,48,50) to said drive means (24,25,28,30,32) and having a looping blade (88) having an eyelet (100) carrying a loop (166) said secondary wire   (102), said looping blade (88) being mounted in motion   within said claw chamber (58) to move said blade (88) along a path (107) immediately adjacent to said needle path (150) (40) and fully located on a c8te said trajectory (150) of the needle, in order to come into contact with said loop (172) of the primary wire (41) carried by said needle (40), and to introduce said loop (166) of secondary wire (102) in said loop (172) of   primary thread (41) during sewing.   18. Sewing machine according to claim 17, characterized   characterized in that said looping blade (88) comprises a rigid upright (92) and an elongated arm (96) extending outwardly and cantilevered from said upright (92), said eyelet (100) being adjacent to the free end (98) of said arm (96).   Sewing machine according to claim 18, characterized in that said arm (96) extends from said upright (92) a distance substantially equal to   at least four times the diameter of said needle (40).   20. Sewing machine according to claim 19, characterized in that said eyelet (100) of said looping blade (88) moves along said path (107) of the blade and that the envelope positions occupied by said locking eyelet (100) defines a plane (200) which is fixed with respect to said path (150) of the needle (40).   21. Sewing machine of the two-wire type, for closing bags, for sewing a bag (52) when the bag moves downstream (80) in said machine (10), said machine comprising: a housing rigid member (20) having a claw chamber (58), driving means (24,25,28,30,32) carried by said housing (20), primary and secondary sources (16,18) of wires, adjacent to said housing (20), and intended to supply primary wire (41) and secondary wire (102), respectively, a set (34,36,38) for driving a needle   (40), movably mounted relative to said housing (20),   connected to said drive means (24,25,28,30,32), and having a needle (40) reciprocated along a path (150) of the needle to enter and exit said claw chamber (58), said needle (40) having an eye (47) into which a loop (172) of said primary wire (41) is carried, a claw assembly (74) carried by said housing (20) , operatively connected to said drive means (24,25, 28,30,32), and having a claw (78) movable reciprocatingly and facing the bag (152), and cooperating with a presser foot assembly ( 72) to advance the bag (152) downstream (81) beyond the reciprocating needle (40), while sewing the bag (152), a needle plate (66) ) adjacent said claw (78) and having an opening (112) for passage of the needle, communicating with said claw chamber (58) and positioned along said path (150) of the needle (40) for accommodating said needle (40) during sewing, characterized in that it further comprises an improved loop assembly comprising: a skewer drive shaft (52) having a central axis (53); ) and movably mounted relative to said housing (20), and operably connected (44, 46, 48, 50) to said drive means (24, 25, 28, 30, 32) so as to reciprocate said shaft ( 52) on an arc, about said central axis (53) of the shaft, and a looping unit (54) attached to said looper shaft (52) and having a looping blade (88) having a bearing eyelet (100) a loop (166) of said secondary wire (102), said looping blade (88) swinging in position immediately adjacent to said path (150) of the needle (40) and across said arc, in response to a pivoting of said shaft looper (52), so that the envelope of the positions of said loop eyelet (100) defines a plane (200) intersecting the downstream travel direction (80) of the bag (152) at an angle not greater than 45 to reduce wear and breakage of the wire (102) during engagement of said primary wire loop (172) (41) and inserting said secondary wire loop (166) into said primary wire loop (41) while sewing.   22. Sewing machine according to claim 21, characterized   characterized in that said angle does not exceed 20.   Sewing machine according to claim 22, characterized in that said angle is between 10 and 20.   Sewing machine according to claim 23, characterized   characterized in that said looping blade (88) comprises an arm (96) having. a free end (98), said loop eyelet (100) being adjacent said free end (98), and said free end (98) of said arm (96) swings upstream in a substantially direction opposing the downstream travel direction (80) of the bag (152) during insertion of said secondary wire loop (102) into said loop   (172) of primary wire (41) to take advantage of the quantity   movement of the bag (152) to tighten the points in training in the bag (152).