FR2878241A1 - AUTOMATIC MACHINE FOR THE FORMATION OF A NODE USING A TWINE AT THE END OF A TUBULAR SHEATH IN ORDER TO SHUT IT OFF BY CONSTRICTION UNDER THE CLAMPING OF THE NODE - Google Patents

Abstract

The machine for forming a knot using a string on a tubular sheath comprises in particular a mechanism (4) for forming two loops on the string and for juxtaposing the two loops formed. This mechanism is constituted by: - a rotary drive shaft (40) driven in rotation according to one turn and during the completion of the turn, in translation according to an upward and downward movement, - and two flaps (42) articulated to a support (43) fixed to the drive shaft (40), said flaps being provided with pins (46) for gripping the twine and being arranged in a horizontal position with a view to forming the two loops by rotation and translation of the together. The two flaps are then brought opposite one another in order to superimpose the two loops formed. The sheath to be closed is then engaged in these two loops and the knotting is operated by traction on the string.

Description

2878241 1

  AUTOMATIC MACHINE FOR THE FORMATION OF A NODE USING A TWINE AT THE END OF A TUBULAR SHEATH IN ORDER TO SHUT IT OFF BY CONSTRICTION UNDER THE CLAMPING OF THE NODE.

  The present invention relates to an automatic machine for the formation of a knot using a string at the end of a tubular sheath to be closed by constriction of its wall under the effect of tightening the knot, this tubular sheath may be pre-filled with a meat food product for example or be intended to receive a food product. The food product may be sausage meat or the like.

  Known state of the art machines for forming with one string a knot at each end of a tubular sheath. Such a machine is in particular known from patent application EP 80 422. This machine for forming the knot uses a mechanism which forms two loops on the yarn by vertical linear displacement of two gripping hooks and which ensures the superposition of the two loops formed by horizontal movement of two other gripping hooks, these two hooks moving away from each other. In these two loops is engaged by linear advance movement a gripper which snap the end of the sheath to ligate and which by recoil motion brings the end of the sheath in the two superposed loops and the maintenance in these two loops during the knotting that is done by pulling on both ends of the thread.

  It has been found that the knot formed in this way does not provide under certain conditions a good ligaturing of the end of the sheath, the knot 25 being able to be undone.

  The object of the present invention is to solve the above-mentioned disadvantage by using a machine capable of producing a more solid knot incapable of being discarded.

  For this purpose the automatic machine according to the invention, for the formation of a knot using a string 1 at the end of a flexible tubular sheath in order to close it by constriction of its wall under the effect the tightening of the knot which tightening is performed by pulling on the string, said machine comprising a means for keeping the part 1 of the string on which the knot is to be formed in a horizontal position, said part 1c of string being maintained horizontally by clamp members opposite a mechanism for forming two loops on said twine portion and juxtaposition of the two loops formed and said machine further comprising means for introducing the end of the sheath in the two loops by relative movement of the end of the sheath relative to the two said loops, is essentially characterized in that the mechanism of formation of the two loops on the part (la) of twine and juxtaposition of the two b orcles formed comprises: - a vertical drive shaft rotatable about its longitudinal axis, engaged in a bearing of the machine frame and coupled to a rotational drive assembly in one turn, and during the completion of the turn, in translation according to an upward and downward movement, and two movable flaps each articulated along a horizontal axis to a support rigidly fixed to the lower end of the drive shaft, said flaps being associated with a positioning means, which ensures the holding in position of the latter is horizontally coplanar and diametrically opposite, or vertically facing each other, each of said flaps, opposite its axis of articulation the support having a notch passing therethrough from one side to the other according to its thickness, which notch is open on that of the banks of the flap opposite to the axis of articulation and each of said flaps in per Iheri of its notch being provided with several gripping pins of the portion of twine held horizontal, said pins projecting from that of the faces of the flap facing the portion (la) of string, said flaps for the purpose of forming the knot being positioned horizontally above the string portion (1a) and symmetrically with respect to a geometrical plane P containing the longitudinal axis of the string portion (1a) and parallel to the hinge axis of each flap on the support and then the drive shaft being rotated and driven downwards so that the pawns of the flaps are successively apprehend the portion (la) of string, and before said pions come apprehend a second the string portion (the), the drive shaft, being moved upwards to bring the said spacing pieces of the portion (la) of string not yet apprehended, the continuation of the rotation it tree on the remaining fraction of tower allowing the formation of two opposing loops held by the pins around the notches, the flaps then being brought back in vertical position by the positioning means in order to place the two loops formed in juxtaposition relation and thus to form a knot to affix to the end of the sheath.

  The knot thus formed between the fingers of the flaps is then transferred onto the end of the sheath. This action is performed by means of introducing the end of the sheath into the two loops, this introduction being effected by relative movement of the end of the sheath relative to the two said loops. According to an additional feature of the invention, said means comprises: a horizontal tubular pre-mandrel mandrel, able to move horizontally in translation along its horizontal axis, said mandrel being associated at its rear end with a motor means which positions it in a position d erasure in which it is moved away from the movable flaps is in a waiting position of the node in which it is engaged in the notches of the movable flaps and in the loops of the node, said flaps being in a vertical position, a pair of jaws mounted in the mandrel and associated with a motor member which arranges it in a first position in which it is fully retracted into the mandrel and a second position in which it is extended from the mandrel, the two jaws being in the open position while waiting for the end of the sheath, and a transfer sleeve slidably mounted on the pre-mandrel tying, and associated with a drive member driving in translation along the mandrel, which drive member is activated after the clip with the end of the sheath taken between the jaws has been retracted into the mandrel and after the movable flaps have been returned to the horizontal position so that the node formed in the flaps is transferred to the precoupling mandrel, the activation of the motor causing the sliding of the transfer sleeve on the mandrel and the driving of the knot, by sliding on the mandrel, to the sheath to be closed.

  The knot is then tightened by pulling on the corresponding part (s) of twine.

  According to another characteristic of the invention, one of the gripper members for holding the horizontal string part (1a) is fixed and occupies an upstream position with respect to the loop formation mechanism of the knot and the other is rotatable about the longitudinal vertical axis of the drive shaft of the formation mechanism of the two loops of the node, and this between an upstream gripping position of the free end of the string, which position is located close to said first gripper member and a downstream position angularly offset from the previous one, and vice versa, the movable gripper member, during its movement from the upstream position to the downstream position partially winding the string around a first return roller then around a second return roller, the axes of rotation of said rollers being vertical and the movable clamp member being moved from one to the other position and vice versa by a motor assembly.

  Other advantages, objects, and features of the invention will become apparent on reading the description of a preferred embodiment, given by way of non-limiting example, with reference to the appended drawings in which: FIG. 1 is a front view of a machine according to the invention; FIG. 2 is an exploded view of a machine according to the invention; FIG. 3 is a view of the front face of the machine with the FIGS. wire guide members, not shown in FIGS. 1 and 2; FIG. 4 is a perspective view of the front face; FIG. 5 is a front view of the mechanism for forming the two loops on the string and juxtaposition of the two loops, - Figure 6 is a right view of Figure 5, - Figure 7 is a top view of said mechanism, - Figure 8 is a schematic bottom view of said mechanism, the flaps being in a horizontal position. and two loops being formed; FIG. 9 is a sectional view of the means of transfer of the two loops formed towards the end of the sheath, the mandrel of this means not being shown, FIG. 10 is a sectional view of the mandrel of the loop transfer means, FIG. a perspective view of the mandrel of the transfer means, - Figure 12 is a front view of a movable clamp member, - Figure 13 is a perspective view of a movable clamp member, - Figure 14 is a sectional view showing the motor assemblies associated with the loop formation mechanism of the node and the movable abutment member; FIG. 15 is a perspective view of a transfer clip member, as shown, the machine automatic according to the invention, is intended for the formation of a knot using a string on the end of a flexible tubular sheath to close it by constriction of its wall, this sheath being designed to receive a food product for example meat.

  The machine according to the invention comprises on a frame B a horizontal holding means of the part 1a of the string on which the knot must be formed, said part 1c of string being held horizontally by clamp 2, 3 opposite a mechanism 4 for forming two loops on said part of string and juxtaposition of the two loops formed. The machine further comprises a means 5 for introducing the end of the sheath into the two loops by relative movement of the end of the sheath with respect to said two loops. The machine also has on its front face, shown in Figure 3, 6 members for guiding the string and tensioning the latter, the clamp member 2 being carried by this front face.

  According to the invention, the mechanism 4 for forming the two loops on the twine portion and juxtaposition of the two loops formed comprises: - a drive shaft 40, vertical, rotating, about its longitudinal axis, engaged in a bearing of the frame B of the machine and coupled to a motor assembly 41 rotational drive according to a lathe, and during the completion of the lathe, in translation in an upward and downward movement, - and two movable flaps 42 each articulated along an axis horizontal to a support 43 rigidly fixed to the lower end of the drive shaft 40, said flaps 42 being associated with a positioning means 44, which 2878241 6 ensures the maintenance in position of the latter is horizontal of coplanar manner and diametrically opposite, or vertically opposite each other, each of said flaps, opposite its axis of articulation to the support having a notch 45 across integrally according to its thickness, which notch is open on that of the banks of the flap opposite to the axis of articulation and each of said flaps 42 on the periphery of its notch being provided with several pins 46 for gripping the part of the of string kept horizontal, said pins 46 projecting from that of the flap faces facing the portion (1 a) string.

  Preferably, as can be seen in FIG. 8, each flap 42 is associated with two pins 46, these pins being arranged facing respectively the two ends of the notch 45, correspondingly. A third piece may be provided on the periphery of the notch and arranged, considering the perimeter of the notch midway between the first two pieces. These third pieces are represented in strong dotted line in FIG.

  According to the preferred embodiment, the drive shaft 40 is splined and is slidably mounted in a spline ring mounted in the guide bearing. This ring is equipped with an external toothing, engaged with a rack actuated by a motor member of the pneumatic cylinder type. This drive member, the rack and the pinion of the fluted ring constitute the motor assembly 41.

  Advantageously, the drive shaft 40 of the mechanism 4 is equipped in the upper part with a radial arm 47 carrying a rolling roller 48 and on the machine frame B is mounted a fixed cam 49 provided with a raceway without end on which bears and rolls the roller 48, the profile of said path determining the height position of the shaft 40 and flaps 42 and in relation to their angular position about their vertical axis of rotation and said path having a portion horizontal plane, lower, an ascending part, an upper horizontal flat part and a descending part.

  The cam 49, of tubular form is mounted around the upper part of the drive shaft 40.

  Preferably the positioning means 44 of the two flaps 42 is constituted by two drive members respectively associated with the two flaps, these drive members being advantageously constituted by pneumatic cylinders. Each of these cylinders is articulated respectively to a structure carried by the support 43 and the flap 42 corresponding.

  This support 43 is preferably in the form of a profile of U-shaped cross-section, the U-shape being turned downwards. As can be seen in Figure 5 this support 43 forms a housing 43a between the flaps, open downwards, and limited by a horizontal upper face, said upper face being disposed at a higher height level relative to the flaps.

  Each gripping pin 46 will be of frustoconical shape. Through the small base of the truncated cone, each peg is applied against the corresponding face of the shutter. This arrangement ensures the maintenance of the string in the flaps of the mechanism 4 during the node forming operation.

  The flaps 42, with a view to the formation of the knot, are positioned horizontally above the portion (la) of string, as well as symmetrically with respect to a geometrical plane P containing the longitudinal axis of the part (la) string on the one hand and parallel to the axis of articulation of each flap 42 to the support 43 on the other.

  Then the drive shaft 40 is rotated and driven down so that the pins 46 of the flaps 42 are successively apprehend the part of the string. Before the pins 46 come to apprehend a second time the part of string, the drive shaft 40, is moved upwards to bring said pins 46 spaced from the part 1 to a string so that the latter do not get caught by these pieces. The continued rotation of the drive shaft 40 on the remaining tower fraction allows the formation of two opposite loops maintained by the pins 46 around the notches 45. Subsequently, the flaps 42 are returned to the vertical position by the positioning means 44 for placing the two loops formed in juxtaposition relation and thus forming a node to be affixed to the end of the sheath.

  Preferably, there is provided a gripping finger, not shown, of the part 1a of string. This gripping finger is disposed upstream of the mechanism 4 for forming the two loops and juxtaposing them, and is associated with a motor member which brings it to the upper position so as to bring the mechanism 4 upwards to the upper position. unshielded upstream strand 2878241 8 of the part la of twine when the two loops are formed and the flaps 42 are still in horizontal position. Advantageously, this strand is introduced into the housing 43a of the support 43.

  The means 5 for introducing the end of the sheath into the two loops by relative movement of the end of the sheath with respect to the said two loops, receives the knot and ensures the transfer of the knot towards the end of the sheath. to tie. This means 5 comprises: - a mandrel 50 of preenouing, tubular, horizontal, horizontally movable in translation along its horizontal axis, said mandrel being associated by its rear end with a motor means 51 which positions it is in an erasing position according to which it is moved away from the movable flaps 42, or in a waiting position of the node in which it is engaged in the notches 46 of the movable flaps 42 and in the loops of the node, said flaps 42 being in a vertical position, - a gripper 52 to two jaws, mounted in the mandrel 50 and associated with a drive member 520 which has a first position in which it is fully retracted into the mandrel 50 and a second position in which it is deployed from the mandrel 50, the two jaws having arranged in the open position waiting for the end of the sheath, and a transfer sleeve 53 slidably mounted on the prenouing mandrel 50, and associated with a drive member 54 driving in translation along the mandrel 50, which drive member 54 is activated after the clamp 52 with the end of the sheath taken between the jaws has been retracted into the mandrel 50 and after the movable flaps 42 have been returned to the horizontal position so that the node formed in the flaps is transferred to the precoupling mandrel 50, the activation of the motor 54 causing the sliding of the transfer sleeve 53 on the mandrel 50 and the driving of the node, by sliding on the mandrel, towards the sheath to be closed.

  According to the preferred embodiment, the means 5 comprises a vertical fixed wall 55 provided with a through bore in which is engaged in fixing, a horizontal tubular sheath 56 in which is slidably mounted the mandrel 50 and on which is mounted sliding the transfer sleeve 53.

  The motor means 51 is for example constituted by a pneumatic cylinder 511 hinged on the one hand to the vertical wall 55 and on the other hand to a lever structure 512 articulated to a yoke 513 fixed to the wall 55. This lever structure comprises at a distance from its hinge axis at the yoke 513, two rollers 514 which are respectively engaged in two grooves 515 formed in a block 516 integral with the mandrel 50.

  The clamp 52 has two jaws of unequal length, the longest jaw occupying a lower position. This arrangement facilitates the engagement of the end of the sheath between the jaws.

  The drive member 520 associated with the clamp 52 is for example constituted by a pneumatic cylinder. This cylinder is fixed by its body to the block 516. Each of the two jaws of the clamp 52 is provided with a shoulder, which when the clamp is moved in the direction of its deployment relative to the mandrel, abuts against a mounted cross pin fixedly in the mandrel. This arrangement ensures automatic opening of the jaws of the clamp. During retraction of the clamp in the mandrel, the jaws are disengaged from their abutment pins and bearing against the inner face of the mandrel, are returned to the closed position and thus clamping the corresponding end of the sheath.

  Advantageously, the clamp 52 is associated with a fixed cutting member 57 mounted in the mandrel 50 for cutting, during retraction of the sheath into the mandrel, the free end of the sheath overflow relative to the clamp. This cutting member is lateral to the clamp and is in the form of an inclined cutting blade.

  The transfer sleeve 53 is advantageously provided with a wiper seal to prevent the node from engaging in the internal bore of the latter. The sleeve 53 is provided with a radial tab to which is fixed the motor member 54.

  Preferably, this driving member is constituted by a pneumatic cylinder fixed by its rod to said tab and by its body to the fixed wall 55.

  After transfer of the node on the end of the sheath, said node is tightened on said end by pulling on the corresponding part (s) 2878241 of twine. For this purpose, there is provided a traction means of the portion 1a of the string to tighten the node around the sheath, the traction means being constituted by a movable finger 60 actuated by a motor member advantageously constituted by a pneumatic cylinder. Then the section of the string is severed by a cutting member 8 mounted movably from bottom to top and from top to bottom and carried by an actuating motor member for example a pneumatic cylinder. Then the motor of the clamp 520 is activated for the purpose of loosening the clamp and disengaging the sheath.

  According to the preferred embodiment, one of the holding clip members of the portion of the string is horizontally fixed and occupies an upstream position with respect to the mechanism 4 forming loops of the node and the other 3 is rotatable about the longitudinal vertical axis of the drive shaft 40 of the mechanism 4 for forming the two loops of the node, and this between an upstream gripping position of the free end of the string, which position is located near said first gripper member 2 and a downstream position, angularly offset from the previous one, the movable gripper member 3, during its movement from the upstream position to the downstream position partially winding the string around a first return roller 61 and then around a second return roller, the axes of rotation of said rollers being vertical and the movable clamp member 3 being moved from one to the other position and vice versa by a motor assembly 30 .

  The first return roller 61 in combination with the gripper member 2 and the gripper member 3 ensures that the string portion 1a is held horizontally and in the geometric plane P. The second return roller in combination with the gripper member 3 held apart laterally from the mechanism 4, the string portion, downstream from the first roller 61.

  Advantageously, the first return roller 61 is mounted on a mount 62 movable horizontally between a first position of partial winding of the string and a second recoil position corresponding to a pull on the string, said frame 62 being moved from one side to the other. in the other position and vice versa by a motor member 63 advantageously constituted by a pneumatic cylinder. Thus this first return roller 61 can participate with the movable finger 60, the tightening of the node on the end of the sheath.

  The gripper member 3 comprises a radial horizontal arm 31 end of which is fixed a ring gear 32 engaged on a hollow guide bearing traversed from one side by the drive shaft 40. With this ring gear 32 cooperates a drive rack actuated by a drive member of the pneumatic cylinder type. This drive member, the drive rack and ring gear 32 constitute the motor assembly 30.

  The movable clamp member 3 comprises a fixed lower jaw 33 and an upper jaw 34 movable vertically and actuated by a motor member 35 of the pneumatic jack type. The movable upper jaw 34 is for example constituted by a cylindrical finger fixed to the end of the cylinder rod. This jaw 34 is guided in translation in the bore of a tubular body member body 36 fixed to the cylinder body. In the lower part of the clamp member body is formed the lower fixed jaw 33. The radial arm 31 is fixed to the cylinder body, in the upper part thereof.

  In combination with this movable gripper member 3, the machine is provided with a transfer gripper member 7 movable between a rear position and a front position and vice versa, under the action of a motor member ( 70), said transfer clip member 7, in its rear position being disposed behind the downstream position of the movable clamp member (3), and said transfer clip member (7) during its movement. from its rear position to its forward position, catching the end of the string carried by the movable clamp member (3) and bring said end substantially in the plane P. In combination with these features, the second return roller on which is partially wound the twine is mounted on a frame movable between an initial position of partial winding of the string and a low position in which the roller is released from the string, said frame being moved from one to the other position and conversely by a motor unit. The free end of the string is transferred to the plane P after formation of the two loops of the node and before juxtaposition of the two loops by pivoting the flaps 42 to their vertical position. Always before the flaps are pivoted to their vertical position, the second return roller is brought into the erasing position and the twine strands snagged by the fixed clamp member and the transfer clamp member and occupying an upstream position by relative to the mechanism 4 are introduced into the housing 43a under the ascending effect of the movement of the gripping finger. Subsequently the flaps 42 are rotated to their vertical position. This arrangement makes it possible to associate the formed node with a suspension loop.

  After forming this loop, the upstream strand of the string portion 1a is cut by the cutting member 8 and the motor 520 of the clamp is activated in the direction of opening of the jaws in order to disengage the sheath of the sheath. the influence of the latter.

  According to the preferred embodiment, the transfer clip member 7 has a body 72 to which is attached a splined support arm 71 engaged in a grooved guide bearing mounted in the wall 55. To this body is fixed the driving member 70 which is advantageously constituted by a pneumatic cylinder. The rod of this jack will be fixed to the body 72, the body of the jack will be fixed to the wall 55. The body 72 carries a drive member 73 for actuating a movable jaw 74, this movable jaw being carried by the body 72. the top part. The fixed jaw is constituted by the body itself. The movable jaw 74 has an upper clearance 75, in the path of which, is located the lower part of the movable clamp member 3 when the latter is in the downstream position. In the open position the movable jaw by its clamping face is located at a level of height greater than that of the clamping face of the fixed jaw of the movable clamp member 3, the clamping face of the fixed jaw of said transfer clip member located at a lower height level. This arrangement allows to catch the string.

  With the machine according to the invention it is possible to bind by a single string several tubular sleeves. To limit the distance between the nodes is provided a retractable stop which is positioned on the path of the movable clamp member to limit the angular movement. The length of the path of the movable gripper member, however, will be sufficient to partially wind up the stop on the first return roller 61. In combination with this characteristic, the machine may be equipped with a second cutting member to cut, after realization of the first node and transfer and tightening of the latter on the first sheath, the downstream strand of the portion of the string to limit its length.

  Finally, the machine as described will advantageously be equipped with a movable member for releasing the string from the right-of-way of the first return roller.

  The machine is mainly intended to form knots on sausage casings intended for example for the manufacture of sausages, sausages and other sausages.

  It goes without saying that the present invention is not limited to the previously described embodiment but on the contrary it embraces the various embodiments.

2878241 14

Claims (3)

CLAIMS.   11 Automatic machine for forming a knot using a string at the end of a flexible tubular sheath in order to close it by constricting its wall under the effect of tightening the knot, which clamping is done by pulling on the string, said sheath containing or being intended to contain a food product and said machine comprising means for keeping the part (1a) of the string on which the knot must be formed, said part of twine being held horizontally by gripping members (2, 3) facing a mechanism (4) for forming two loops on said string portion and juxtaposing the two loops formed and said machine further comprising a means for introducing (5) the end of the sheath into the two loops by relative movement of the end of the sheath with respect to said two loops, characterized in that the mechanism (4) for forming the two loops on the part (1a) of twine and juxtaposition of the two formed loops comprises: a vertical drive shaft (40) rotatable about its longitudinal axis, engaged in a bearing of the machine frame (B) and coupled to a drive motor assembly (41); ) in rotation according to a turn, and during the completion of the turn, in translation in an upward and downward movement, - and two movable flaps (42) articulated each along a horizontal axis to a support (43) rigidly fixed to the end lower part of the drive shaft (40), said flaps being associated with a positioning means (44), which ensures the holding in position of the latter is horizontally coplanar and diametrically opposite, or vertically facing each other, each of said flaps, opposite its axis of articulation to the support (43) having an indentation (45) passing therethrough from one side to the other according to its thickness, which indentation (45) is open on this the edges of the flap opposite to the axis of articulation and each of said flaps (42) at the periphery of its notch being provided with several pins (46) for gripping the portion of string kept horizontal, said pins protruding on that flap faces facing the string portion (1a), said flaps (42) for forming the knot being positioned horizontally, above the string portion (1a), and symmetrical with respect to a geometrical plane (P) containing the longitudinal axis of the string part (1a) and parallel to the axis of articulation of each flap (42) to the support (43) and then the shaft of the drive (40) being rotated and driven downwards so that the pawls (46) of the flaps successively capture the portion (la) of string, and before said pieces (46) come to apprehend a second time the part (la) of string, the drive shaft (40), being mature worm s upwards to bring said pieces (46) spaced from the portion (la) of string not yet apprehended, the further rotation of said shaft (40) on the remaining fraction of tower allowing the formation of two opposite loops, maintained by the pins (46), around the indentations, the flaps (42) being then returned to the vertical position by the positioning means so as to place the two loops formed in juxtaposition relation and thus form a knot to be affixed to the end of sheath.   2 / Machine according to claim 1, characterized by a gripping finger of the portion (1a) string, arranged upstream of the mechanism (4) for forming the two loops and juxtaposition thereof, said finger being associated with an organ motor which brings it in the up position so as to bring the upstream loop of the string part (la) to the mechanism (4) upwards when the two loops are formed and the flaps (42) are still in position horizontal.   3 / Machine according to claim 1 or claim 2, characterized in that the means (5) for introducing the end of the sheath into the two loops by relative movement of the end of the sheath relative to the two said loops, comprises: a horizontal tubular prenouging mandrel (50) movable horizontally in translation along its horizontal axis, said mandrel being associated at its rear end with a motor means (51) which positions it in an erasure position according to it is removed from the movable flaps (42), or in a waiting position of the node in which it is engaged in the indentations (45) of the movable flaps and in the loops of the node, said flaps (42) being in the vertical position , A gripper (52) with two jaws, mounted in the mandrel and associated with a motor member (520) which disposes it in a first position in which it is fully retracted into the mandrel (50) and a second position in which it is extended from the mandrel (50), the two jaws being in the open position waiting for the end of the sleeve, and a transfer sleeve (53) slidably mounted on the mandrel mandrel ( 50), and associated with a drive member (54) driving in translation along the mandrel, which drive member (54) is activated after the clamp (52) with the end of the sheath taken between the jaws has been retracted into the mandrel (50) and after the movable flaps (42) have been returned to the horizontal position so that the node formed in the flaps (42) is transferred to the precoupling mandrel, the activation of the member (54) causing the transfer sleeve to slide on the mandrel and to drive the knot, by sliding on the mandrel, towards the sheath to be closed.   4 / Machine according to claim 3, characterized in that the clamp (52) is associated with a cutting member (57), fixed mounted in the mandrel for cutting, during the retraction of the sheath in the mandrel (50) , the free end of the sheath overflow relative to the clamp (52).   5 / Machine according to claim 2 or claim 3, characterized in that it is equipped with a pulling means of the portion (1a) of the string to tighten the node around the sheath.   61 Machine according to any one of the preceding claims, characterized in that the drive shaft (40) of the mechanism (4) for forming the two loops is equipped in the upper part with a radial arm (47) carrying a roller rolling surface (48) and that on a frame (B) of said machine is mounted a fixed cam (49) provided with an endless race on which the roller (48) bears and rolls, the profile of said path determining the position in height of the shaft (40) and the flaps (42) in relation to their angular position about their vertical axis of rotation and said path having a horizontal flat part, a lower part, an ascending part, an upper horizontal flat part and a descending part.   A machine according to any one of the preceding claims, characterized in that one (2) of the holding clip members of the horizontal string portion (1a) is fixed and occupies an upstream position by relative to the loop formation mechanism (4) of the node and that the other (3) gripper member is rotatable about the longitudinal vertical axis of the drive shaft (40) of the mechanism (4) of forming the two loops of the node, and this between an upstream gripping position of the free end of the string, which position is located near said first gripper member (2) and a downstream position, angularly offset from the previous one , the movable gripper member (3), during its movement from the upstream position to the downstream position partially winding the string around a first return roller (61) and then around a second return roller, the axes of rotation of said rollers being vertical and the body (3 ) mobile clamp being moved from one to the other position and vice versa by a motor assembly (30).   8 / Machine according to claim 7, characterized in that the first return roller (61) is mounted on a mount (62) movable horizontally between a first position of partial winding of the string and a second recoil position corresponding to a traction on the string, said mount (62) being moved from one to the other position and vice versa by a motor member (63).   9 / Machine according to claim 7 or claim 8, characterized in that it is provided with a transfer clip member (7) movable between a rear position and a front position and vice versa, under the effect of action of a motor member (70), said member in its rear position being disposed behind the downstream position of the movable clamp member (3), and said transfer clip member during its movement of its rear position to its forward position, catching the end of the string carried by the movable clamp member (3) and bring said end substantially in the plane P, and the second return roller on which is partially wound the string is mounted on a frame movable between an initial position of partial winding of the string and a low position in which the roller is released from the string, said frame being moved from one to the other position and vice versa by a motor member , the libr e of the string being transferred to the plane P after formation of the two loops of the node and before juxtaposition of the two loops 2878241 18 by pivoting the flaps to their vertical position, the second return roller being brought into the erasing position always before pivoting flaps (42) to their vertical position, which ensures the formation of a suspension loop associated with the realized node.   10 / Machine according to any one of claims 7 to 9 characterized by a retractable stop positioned on the path of the movable clamp member (3) to limit the angular movement.