US3861428A - Weft-injection system for shuttleless loom - Google Patents

Abstract

Two counteroscillating lances on opposite sides of a set of warp threads serve for the unidirectional transportation of a succession of weft carriers across the shedded warp, one lance pushing each weft carrier from the insertion side to about the middle of the shed where the carrier is transferred to the other lane pulling it through the remainder of the shed to the extraction side. The retrieved carriers are returned, in the order of their arrival at the extraction side, to the insertion side by a conveyor mechanism synchronized with the lance drive. The reciprocating strokes of the two lances are relatively dephased so that the inserting lance moves briefly in the same direction as the extracting lance at the instant of transfer.

Description

United States Patent Conte et al.

WEFT-INJECTION SYSTEM FOR SHUTTLELESS LOOM Inventors: Georges Conte,

Villeurbanne-Rhone; Pierre Royer, Vaulx-en-Velin-Rhone; Edmond Narboux, Bron-Rhone, all of France Mecoutil Societe a Responsibilite Limitee, Anatole, France Filed: May 30, 1973 Appl. No: 365,077

Assignee:

US. Cl. 139/126, 139/141 Int. Cl D03d 47/12 Field of Search 139/122, 123, 125, 126,

References Cited UNITED STATES PATENTS 3,603,352 9/1971 Golobart 139/127 Primary ExaminerHenry S. Jaudon Attorney, Agent, or Firm1(arl E. Ross; Herbert Dubno [57] ABSTRACT Two counteroscillating lances on opposite sides of a set of warp threads serve for the unidirectional transportation of a succession of weft carriers across the shedded warp, one lance pushing each weft carrier from the insertion side to about the middle of the shed where the carrier is transferred to the other lane pulling it through the remainder of the shed to the extraction side. The retrieved carriers are returned, in the order of their arrival at the extraction side, to the insertion side by a conveyor mechanism synchronized with the lance drive. The reciprocating strokes of the two lances are relatively dephased so that the inserting lance moves briefly in the same direction as the extracting lance at the instant of transfer.

10 Claims, 19 Drawing Figures PATENTED JANZI I975 SHEET 2 OF 3 i 3 mw m v WiQ L: mm mm AAA/A WEFT-INJECTION SYSTEM FOR SHUTTLELESS LOOM FIELD OF THE INVENTION Our present invention relates to a loom of the shuttleless type in which a weft carrier is transported through a shedded set of warp threads with the aid of two Iances entering the shed from opposite sides.

BACKGROUND OF THE INVENTION In conventional looms of this type the two counteroscillating Iances move halfway into the shed toward each other, one lance pushing the carrier ahead until it encounters the other lance to which it is then transferred for extraction from the shed. The carrier, dragging its weft thread behind it, moves back and forth through the changing shed into which it is alternately inserted from the left and from the right, each lance acting alternately as a pusher and as a puller.

Although such systems operate satisfactorily in principle, they are relatively complex in their construction. In particular, the mechanism for alternately transferring the weft carrier from the left lance to the right lance and then from the right lance to the left lance is somewhat involved.

OBJECTS OF THE INVENTION The general object of our present invention is to provide a simplified weft-injection system for a loom of the character referred to.

A more specific object is to provide a smoothly operating mechanism for transferring a weft carrier from one lance to another in a system of this character.

SUMMARY OF THE INVENTION These objects are realized, in accordance with the present invention, by providing each weft carrier with first coupling means engageable by a first lance, hereinafter referred to as the inserting lance, and with second coupling means engageable by the second lance, hereinafter referred to as the extracting lance, the second coupling means overriding the first coupling means in a position of momentary simultaneous engagement of a weft carrier by both Iances whereby, upon subsequent separation of the Iances, the carrier remains engaged with the extracting lance after having been introduced into the shed by the inserting lance. Thus, the carrier motion is invariably from the first lance to the second one, i.e., from an insertion side to an extraction side, the carriers being conveyed back from the extraction side to the insertion side by transport means synchro nized with the lance drive but bypassing the warp threads. Upon returning to the insertion side, each carrier passes a loading device which attaches a fresh weft thread to it for entrainment across the shed.

According to a more specific feature of our invention, the weft carrier has a pair of oppositely facing sockets for matingly receiving respective tips of the two Iances; each tip has a resilient or spring-loaded tongue carrying a lug which fits into a peripheral recess of the corresponding socket to hold the lance engaged. However, the lug of the inserting lance has a sloping edge enabling it to be cammed out of its recess whereas the lug of the extracting lance has a straight edge holding it positively engaged in its recess. To disengage the extracting lance from the weft carrier, a release mechanism at the extraction side acts upon a camming formation on the tongue of that lance to withdraw the lug. The camming mechanism also operates to unclamp the entrained weft thread from the carrier.

In accordance with a further feature of our invention, the weft clamp of the carrier is normally closed and has a movable jaw rigid with a swingable guard plate which extends parallel to the direction of carrier motion; this jaw is urged toward an associated fixed jaw by spring means, such as a stack of leaf springs, which also cause a tilting of the guard plate into such a position that the weight of this plate supplements the spring force to hold the clamp closed.

Advantageously, pursuant to yet another feature of our invention, the two Iances are driven by respective cranks which are relatively dephased to an extent letting the two lances move codirectionally and at approximately the same speed at the instant of simultaneous engagement of a weft carrier midway in the shed. This codirectional lance movement ensures a smooth transfer of the weft carrier from the inserting lance to the extracting lance. It thus becomes possible to drive the Iances at an accelerated rate within the shed and to slow them down in the region of the shed edges, i.e. at the points of detachment of a previously entrained weft thread and attachment of a new weft thread.

BRIEF DESCRIPTION OF THE DRAWING The above and other features of our invention will now be described in detail with reference to the accompanying drawing in which:

FIG. 1 is a side-elevational view of a weft carrier according to our invention;

FIG. 2 is a top plan view of the carrier shown in FIG.

FIG. 3 is a longitudinal sectional view of the carrier taken on the line III III of FIG. 2;

FIG. 4 is a front view of a fixed clamp jaw forming part of the carrier of FIGS. 1 3;

FIG. 5 is a bottom view of the clamp jaw shown in FIG. 4;

FIG. 6 is a cross-sectional view taken on the line VI VI of FIG. 1, showing the weft clamp of the carrier in its open position;

FIG. 7 is a view similar to FIG. 6, showing the clamp in closed position and illustrating a guide element for the carrier;

FIG. 8 is a plan view similar to FIG. 2 but showing only the base of the weft carrier with its superstructure removed;

FIG. 9 is a longitudinal sectional elevation of an extracting lance engageable with the carrier of FIGS. 1 8, taken on the line 9 9 of FIG. 10;

FIG. 10 is a top view of the lance shown in FIG. 9;

FIG. 11 is a view analogous to FIG. 9, taken on the line 11 ll of FIG. 12 and showing an inserting lance;

FIG. 12 is a top view of the lance shown in FIG. ll;

FIG. 13 is a view analogous to FIGS. 9 and 11, taken on the line 13 13 of FIG. 14 and showing the assembly of the two Iances and the weft carrier;

FIG. 14 is a top view of the assembly of FIG. 13;

FIG. 15 is an end view of a loom embodying the components of FIGS. 1 14;

FIG. I6 is a partial top view of the loom shown in FIG. 15;

FIG. 17 is a sectional detail view of part of the driving mechanism for one of the Iances;

FIG. 18 is a top view of the assembly shown in FIG. 17; and

FIG. 19 is a face view thereof.

SPECIFIC DESCRIPTION Reference will first be made to FIGS. 15 and 16 which show the principal parts, to the extent here material, of a loom embodying our invention. The loom comprises a frame with two lateral halves 100 and 100" interconnected by braces 101 (only one shown), hall I extending along the insertion side of a set of warp threads 31 (see FIGS. 6 and 7) which pass through a reed 118 on a batten 116. A supply of weft threads is diagrammatically represented by a spool 123 disposed on the insertion side of the loom, a thread 25 from this spool being fed to a loading station 122; The latter, in a manner known per se, lifts the free end of the thread into the path of a weft carrier 1, shown in FIGS. 1 8, l3 and 14, which seizes the thread and transports it through the shed of the warp. Upon the completion of a traverse, loader 122 clamps the thread 25 in place, cuts off the inserted part thereof and presents a new length of thread to the next weft carrier programmed to insert an identical filling into the warp.

The loom frame further comprises mountings 102', 102" for the drive mechanisms of two counteroscillating lances, namely an inserting lance 36 on the left and an extracting lance 55 on the right. Details of these drive mechanisms will be described later. Their source of power is a cam shaft 106, continuously rotated by a nonillustrated motor, which controls the swing of the batten 116 in conventional manner through a rocker shaft 125 and a set of arms 117 supporting the batten on that shaft. A weft carrier aligned with lance 36 on the insertion side of the warp, i.e., above frame half 100', is pushed by that lance into the shed after having been loaded with a thread 25. Substantially midway within the shed, the carrier is transferred to the lance 55 which thereupon pulls it through the remainder of the shed.

An ancillary shaft 119, also driven from shaft 106, operates a pair of bucket chains 121 and 121" on opposite sides of the warp. Chain 121", on the extraction side, picks up each oncoming weft carrier as it is disengaged from lance 55 and detached from the entrained weft, feeding it to an endless compartmented belt 120 which conveys it to chain 121 for delivery to the loading station 122. The conveyor system 120, 121, 121" is so synchronized with the lance drives and the batten swing that a fresh weft carrier always appears in line with the withdrawn inserting lance 36 upon the formation of each new shed. Thus, the weft carriers pass unidirectionally through the shed and are continuously returned to the insertion side via the conveyor belt 120 bypassing the warp.

We shall now describe, with reference to FIGS. 1 8, the construction of a weft carrier 1 designed to cooperate with the two lances 36 and 55 in the manner broadly discussed above.

The weft carrier 1, whose body may consist of plastic material, has a forwardly open front socket 2 and a rearwardly open back socket 4 of rectangular crosssection. A central well 3 accommodates a hinge plate 5 (FIGS. 2, 3 and 6-8) with pintles l3 and 14, centered on a longitudinal swing axis, received in respective recesses l2 and 11. Hinge plate 5 is fastened to a guard plate 6 and is integral with a spur 7 forming a movable clamp jaw for a weft thread 25. Jaw 7 carries an elastic top layer 32 which confronts a serrated surface portion 26 on the underside of a plate 20 constituting a coacting fixed clamp jaw. Plate 20, which forms the upper boundary of socket 4 and is held in position by screws 20', is provided with a cutout 22 acting as a recess in the socket wall; a similar cutout 19 is formed in a plate 18 which constitutes the upper boundary of socket 2. It should be noted, however, that the transverse edges of cutout 22 are beveled whereas those of cutout 19, particularly its leading edge 72, are straight. Plates 18 and 20 advantageously consist of stainless steel.

A large cutout 8 in the bottom of well 3 serves for the discharge of lint and other matter that may accumulate in operation.

Plate 20, which carries a depending weft-guiding pin 27 entering a blind bore 28 in the body of carrier 1, terminates in a sloping lug 21 serving to guide the weft thread into the clamp constituted by jaws 7 and 20. As best seen in FIG. 2, the thread 25 picked up by the lug 21 comes to rest against a rounded corner 33 at an edge of the lug and passes around the pin 27. Jaw 7 is urged upwardly by a stack of leaf springs 10, partly seated in a groove 9, and by the weight of the guard plate 6 in its normal position (FIG. 7) in which this plate is tilted slightly outwardly; the longitudinally extending serra tions 26 serve to hold the thread firmly against the yieldable contact surface 32. Guard plate 6 and a similar, slightly lower plate 29 at the opposite carrier edge serve to prevent any entanglement between the lug 21 and the warp threads 31 (FIGS. 6 and 7) at the upper boundary of a shed traversed by the carrier 1. Plates 6 and 29 advantageously also consist of stainless steel; plate 29 has a hump 30 in the region of lug 21. FIG. 6 illustrates an off-normal erect position of the guard plate into which it is cammed by a ramp 34 (see also FIG. 15) that is adjustably mounted on the extraction side of the frame to unclamp the entrained weft thread 25 upon the completion of the traverse.

The bottom of carrier 1 is formed with lateral ribs 15, 16 which fit into undercuts of a series of brackets 17 (see also FIG. 14) mounted on the batten 116 adjacent its reed 117. The brackets 17, which are aligned with respective reed bars so as not to interfere with the movement of the warp, are spaced apart in the direction of carrier motion by less than the length of ribs 15, 16 so as to form a track for the continuous guidance of the carrier. The same track guides the lances 36 and 55 which are provided for this purpose with respective ribs 53 and 82; see FIGS. 9 14.

We shall now describe, with reference to FIGS. 9 14, the co-operation of lances 36 and 55 with weft carrier 1.

FIGS. 9 and 10 illustrate the extracting lance 55. The body of this lance, like that of lance 36 described hereinafter with reference to FIGS. 11 and 12, is a tube of square cross-section provided at its driven end with a projecting bolt fixed in position by screws 79. Bolt 80 is partly screwed into a threaded sleeve 57 terminating in an eye 58" which accommodates a crank pin as seen in FIGS. 15 and 16; the effective length of the lance 55 can be adjusted by varying the extent of penetration of bolt 80 into sleeve 57. The adjusted position is maintained by a nut 81 bearing upon the sleeve 57.

Fixedly seated in the free end of lance 55 is an elon gated coupling member 56 bracketed by lateral flanges 77, 78 of the lance body and held in position thereon by screws 59. The cross-section of a reduced projecting extremity 60 of member 56 corresponds to that of socket 2 of weft carrier 1 which is open toward this member. A longitudinal channel 73 of member 56 provides room for a tongue 61 which is riveted at 64 to the uppermost leaf spring 65 of a stack of such springs held in place, beyond member 56, by screws 69. The left hand end of tongue 61 carries a hook-shaped lug 62 with a vertically disposed right-hand flank 70 and a sloping left-hand flank 71, the latter flank being cammingly engageable by the front plate 18 of carrier 1 to depress the tongue 61 substantially to the bottom of socket 2 as the carrier approaches the lance for engagement therewith. Upon full insertion of the tip 68 of member 56 into socket 2, hook 62 rises into the recess 19 of plate 18 for positive interlocking therewith as its steep flank 70 comes to rest against the edge 72 of the recess. It should be noted that the end 66 of tongue 61 is overlain by a ledge 67 of the tip 68 and normally engages this ledge from below, thereby limiting the rise of hook 62 under the stress of springs 65.

The right-hand end of tongue 61 is integral with a boss 63 of generally trapezoidal profile, defined by sloping flanks 74, 75 and a substantially level crest 76, which rises above the body of lance 55 for co-operation with a stud 124 (FIG. fixedly positioned on frame half 100" above the path of lance 55. Thus, a withdrawal of this lance to its extreme right-hand position causes the stud 124 to depress the tongue 61 against the force of springs 65 whereby hook 62 is disengaged from recess 19 and the lance is decoupled from the carrier 1. This occurs substantially at the same time that ramp 34 coacts with guard plate 6 to swing the same into its upright position of FIG. 6 with consequent release of thread by clamp 7, 20.

Inserting lance 36, as seen in FIGS. 11 and 12, has a construction similar to but not identical with that of lance 55. Its driven end is also provided with a bolt 51, held in position by screws 50, which is screwed into a threaded sleeve 38 to enable adjustment of the effective length of this lance; a nut 52 holds the sleeve in the selected position. Sleeve 38 has an eye 58 accommo dating a crank pin 105', shown in FIG. 16.

Fixedly seated in the free end of lance 36 is an elongated coupling member 37 bracketed by lateral flanges 48, 49 of the lance body, the cross-section of a reduced projecting extremity 54 of this member corresponding to that of the confronting socket 4 of weft carrier 1. Member 37, held in position by screws 49, forms a longitudinal channel, similar to channel 73 of member 56, accommodating an elastic tongue 41 which has a fixed end clamped between blocks 23, 24 with the aid of screws 43. The mobile end of tongue 41 has a rightward extension 41a provided with a lug 42 having sloping right and left flanks 46 and 47; the end 44 of tongue extension 4la is overlain by a ledge 45 formed by the tip 40 of member 37, this ledge being normally engaged by the end 44 and limiting the rise of lug 42 under the inherent spring force of tongue 41. The sloping flanks of lug 42 enable the introduction of tip 40 into socket 4 with downward depression of this lug until it aligns itself with recess 22, the lug entering this recess for operative but not positive coupling of lance 36 with carrier 1. Thus, upon the subsequent positive engagement of the carrier with lance 55, the divergent motion of the two lances leaves the carrier connected with lance 55 while detaching it from lance 36 as the lug is cammed downwardly so as to depress the tongue extension 41a substantially to the bottom of the socket 4. With the configuration described and illustrated, therefore, the positive coupling 19, 62 of the extracting lance overrides the yieldable coupling 22, 42 of the inserting lance 36.

Lateral flanges 77, 78 and 48, 49 have sloping edges serving to deflect any warp threads encountered by the advancing lance. Flanges 48, 49 also act to elevate the thread holder of station 122 above the lance body at the commencement of an insertion stroke.

FIGS. 13 and 14 illustrate a brief instant during which the carrier 1 is engaged by both lances, this being the moment of transfer from the inserting lance to the extracting lance and occurring approximately midway in the shed. It will be noted that guard plate 6 has a curved extremity 35 overlapping the flange 77 of lance 55 to form therewith a substantially continuous ridge so as to ward off any overlying warp threads that might otherwise become entangled with projecting formations of the carrier traversing the shed.

Advantageously, in the position shown in FIGS. 13 and 14, the two lances 36 and 55 move codirectionally and at nearly the same speed in order to bring about a smooth transfer. This is accomplished, in accordance with a feature of our invention, by driving the two lances 36 and 55 not exactly in phase but with a slight angular offset as illustrated in FIG. 16. Thus lance 36 is reciprocated, through a pitman 103, by a crank 104 lagging by a few degrees (with reference to the fully withdrawn position) behind a similar crank 104" driving the lance 55 through a pitman 103". As a result, the lance 55 introduced into the shed will have begun its rightward return stroke when the lance 36 reaches the end of its insertion stroke; hook 62 snaps into engagement with recess 19 just as the lance 55 leaves dead center and accelerates even as lance 36 slows down to zero speed.

Furthermore, the drive mechanisms for cranks 104' and 104" are designed to rotate these cranks at nonuniform speeds to accelerate the lance motion (as compared with ordinary crank drives) within the shed and to retard them at the opposite ends of their strokes, i.e., in the positions in which weft carriers are picked up by the lance 36 or are released by the lance 55. FIG. 15 shows the drive mechanism 109 for crank 104", within mounting 102", which is identical with the nonillustrated drive mechanism for crank 104 within mounting 102'. Mechanism 109 includes a shaft 110 driving the crank 104" through a pair of bevel gears 108, shaft 110 being in turn driven by main shaft 106 via an eccentric coupling best illustrated in FIGS. l719. The coupling includes a disk 107, rigid with shaft 106, carrying a roller 112 which engages in a groove 113 of a radially extending arm 114 fixed to shaft 110; the axes of shafts 106 and 110 are relatively offset so that roller 112 has a large moment arm in the withdrawn position of the lance (as illustrated in FIGS. 15 to 19) but a small moment arm in the opposite position. Disk 107 also serves as a sheave for driving the shaft 106, by way of conventional V-belts, from its nonillustrated motor.

Gear trains interconnecting shafts 106, 119 and are disposed in a transmission housing 115. FIG. 15 also shows guides 111 for lance 55 which are similar to brackets 17 (FIGS. 7 and 13) and which are duplicated on the other side of the loom for the guidance of lance 36.

The relative acceleration of the lance motion over a major part of a traverse provides a longer period for the operation of the batten, as well as of the associated heddles, whose control cams may therefore be designed to drive these components in a manner minimizing the generated shocks.

We claim:

1. In a loom having shed-forming means for a set of warp threads on a frame and a supply of weft threads on one side of the set, the combination therewith of:

a first lance reciprocably mounted on said frame for introduction into the shedded warp threads from said one side to substantially the middle of the shed;

a second lance reciprocably mounted on said frame for introduction into the shedded warp threads from the opposite side to substantially the middle of the shed;

a plurality of weft carriers each provided with weftgripping means, each weft carrier having first coupling means engageable by said first lance for insertion thereby from said one side into the shed and second coupling means engageable by said second lance for extraction thereby from the shed at said opposite side;

drive means for simultaneously reciprocating said lance in opposite directions and in aligned relationship with momentary simultaneous engagement of a weft carrier by both lances substantially midway of the shed, said second coupling means overriding said first coupling means whereby the weft carrier remains engaged with said second lance upon subsequent separation of said lances;

release means at said opposite side for detaching an oncoming weft carrier from its weft and from said second lance;

transport means on said frame for conveying the detached weft carrier from said opposite side around said set of warp threads to said one side; and

loading means at said one side for attaching a fresh weft thread to an arriving weft carrier prior to in sertion thereof into the shed by said first lance.

2. The combination defined in claim 1 wherein said weft-gripping means comprises a normally closed clamp with a fixed jaw and a movable jaw, said release means including a trip member on said frame at said opposite side engageable with said movable jaw.

3. The combination defined in claim-2 wherein said weft carrier is provided with a swingable guard plate extending parallel to its direction of movement across the shed, said movable jaw being rigid with said guard plate.

4. The combination defined in claim 3 wherein said movable jaw is provided with spring means urging same toward said fixed jaw While holding said guard plate in a tilted position in which the weight of said guard plate supplements the force of said spring means.

5. The combination defined in claim 1 wherein said first coupling means comprises a rearwardly open socket of the weft carrier provided with a first peripheral recess and wherein said second coupling means comprises a forwardly open socket of the weft carrier provided with a second peripheral recess. said first lance having a tip matingly receivable in said rearwardly open socket and provided with a first tongue carrying a first lug fitting into said first recess, said second lance having a tip matingly receivable in said forwardly open socket and provided with a second tongue carrying a second lug fitting into said second recess.

6. The combination defined in claim 5 wherein said first lug has a sloping edge enabling same to be cammed out of said first recess, said second lug having a straight edge holding same positively engaged in said second recess, said second tongue being provided with camming means co-operating with said release means to withdraw said second lug from said second recess upon the arrival of the weft carrier at said opposite side.

7. The combination defined in claim 1 wherein said shed-forming means includes a batten provided with a reed traversed by said warp threads, further comprising spaced-apart guides forming a track for said lances and said weft carriers mounted on said batten at the level of said reed.

8. The combination defined in claim 7 wherein said drive means comprises a continuously rotating cam shaft for the control of said batten, first crank means coupled with said cam shaft for oscillating said first lance, and second crank means coupled with said cam shaft for oscillating said second lance.

9. The combination defined in claim 8 wherein said first and second crank means are relatively dephased for moving said lances codirectionally and at approximately the same speed upon simultaneous engagement of a weft carrier.

10. The combination defined in claim 8 wherein said drive means further includes a cam coupling between said cam shaft and each of said crank means for accelerating said lances within the shed and retarding same in the vicinity of said sides.

Claims (10)

1. In a loom having shed-forming means for a set of warp threads on a frame and a supply of weft threads on one side of the set, the combination therewith of: a first lance reciprocably mounted on said frame for introduction into the shedded warp threads from said one side to substantially the middle of the shed; a second lance reciprocably mounted on said frame for introduction into the shedded warp threads from the opposite side to substantially the middle of the shed; a plurality of weft carriers each provided with weft-gripping means, each weft carrier having first coupling means engageable by said first lance for insertion thereby from said one side into the shed and second coupling means engageable by said second lance for extraction thereby from the shed at said opposite side; drive means for simultaneously reciprocating said lance in opposite directions and in aligned relationship with momentary simultaneous engagement of a weft carrier by both lances substantially midway of the shed, said second coupling means overriding said first coupling means whereby the weft carrier remains engaged with said second lance upon subsequent separation of said lances; release means at said opposite side for detaching an oncoming weft carrier from its weft and from said second lance; transport means on said frame for conveying the detached weft carrier from said opposite side around said set of warp threads to said one side; and loading means at said one side for attaching a fresh weft thread to an arriving weft carrier prior to insertion thereof into the shed by said first lance.

2. The combination defined in claim 1 wherein said weft-gripping means comprises a normally closed clamp with a fixed jaw and a movable jaw, said release means including a trip member on said Frame at said opposite side engageable with said movable jaw.

3. The combination defined in claim 2 wherein said weft carrier is provided with a swingable guard plate extending parallel to its direction of movement across the shed, said movable jaw being rigid with said guard plate.

4. The combination defined in claim 3 wherein said movable jaw is provided with spring means urging same toward said fixed jaw while holding said guard plate in a tilted position in which the weight of said guard plate supplements the force of said spring means.

5. The combination defined in claim 1 wherein said first coupling means comprises a rearwardly open socket of the weft carrier provided with a first peripheral recess and wherein said second coupling means comprises a forwardly open socket of the weft carrier provided with a second peripheral recess, said first lance having a tip matingly receivable in said rearwardly open socket and provided with a first tongue carrying a first lug fitting into said first recess, said second lance having a tip matingly receivable in said forwardly open socket and provided with a second tongue carrying a second lug fitting into said second recess.

6. The combination defined in claim 5 wherein said first lug has a sloping edge enabling same to be cammed out of said first recess, said second lug having a straight edge holding same positively engaged in said second recess, said second tongue being provided with camming means co-operating with said release means to withdraw said second lug from said second recess upon the arrival of the weft carrier at said opposite side.

7. The combination defined in claim 1 wherein said shed-forming means includes a batten provided with a reed traversed by said warp threads, further comprising spaced-apart guides forming a track for said lances and said weft carriers mounted on said batten at the level of said reed.

8. The combination defined in claim 7 wherein said drive means comprises a continuously rotating cam shaft for the control of said batten, first crank means coupled with said cam shaft for oscillating said first lance, and second crank means coupled with said cam shaft for oscillating said second lance.

9. The combination defined in claim 8 wherein said first and second crank means are relatively dephased for moving said lances codirectionally and at approximately the same speed upon simultaneous engagement of a weft carrier.

10. The combination defined in claim 8 wherein said drive means further includes a cam coupling between said cam shaft and each of said crank means for accelerating said lances within the shed and retarding same in the vicinity of said sides.

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