US3665975A

US3665975A - Weft thread inserting mechanism for looms

Info

Publication number: US3665975A
Application number: US3902A
Authority: US
Inventors: Nikolaus Kokkinis
Original assignee: Lindauer Dornier GmbH
Current assignee: Lindauer Dornier GmbH
Priority date: 1970-01-19
Filing date: 1970-01-19
Publication date: 1972-05-30
Anticipated expiration: 1989-05-30

Abstract

This invention relates to a weft thread inserting device for a shuttleless loom comprising a pair of gripper rods having gripper heads mounted on the ends thereof, the gripper rods being mounted for reciprocating movement and being adapted to extend into the shed whereby a weft thread is transferred from one gripper head to the other, and clamping means on the gripper heads for the weft thread adapted to be positively actuated from the exterior of the shed.

Description

United States Patent Kokkinis [451 May 30, 1972 s41 WEFT THREAD INSERTING 3,390,707 7/1968 Scherillo ..139/122 MECHANISM FORLOOMS 3,438,402 4/1969 Kokkinis 139/127 [72] Inventor: Nikolaus Kokkinls, Eriskirch, Gen'nany FOREIGN PATENTS QR APPLICATIONS 1 1 Assisneer Lindauer Dornler Gesellschaft 190,266 12/ 1922 Great Britain ..139/127 R Lindau/Bodensee, Germany 22 Filed: Jan. 19 1970 Primary Examiner-Henry S. Jaudon Attorney-James E. Bryan [21] App1.No.: 3,902 g I v [57] 1 ABSTRACT [52] "139/!27 39,122 N This invention relates to a weft thread inserting device for a r [51] Int. Cl. "D0311 47/18 shuttleless loom comprising a i of gripper rods having 0 r heads mounted on he ends h the g ipp rods being mounted for reciprocating movement and being [56] Rderences Cited adapted to extend into the shed whereby a weft thread is trans- UNITED STATES PATENTS ferred from one gripper head to the other, and clamping means on the gripper heads for the weft thread adapted to be 3,6] Ravella N positively actuated from the exterior ofthe shed. 3,384,126 5/1968 Golobort ..139/123 3,386,477 6/1968 Durand 139/123 10 Claims, 13 Drawing Figures Patented May 30, 1972 3,665,975

9 Sheets-Sheet 1 INVENTOR NIKOLAUS KOKKINIS m Zw ATTORNEY 9 Sheets-Sheet 2 EN I'INTOR NIKQLAUS KOKKINIS nmN Patented May 30, 1972 BY (}M @M nmmm Patented May 30, 1972 3,665,975

9 Sheets-Sheet 5 INVENTOR NIKOLAUS KOKKINIS ATTORN EV Patented May 30, 1972 3,665,975

9 Sheets-Sheet 4 F 6 I mvmmn NIK'OLAU'S KOKKINIS av fm ATTORNEY Patented May 30, 1972 9 Sheets-Sheet 5 v wt 1 mv ENTOR NI KQLAUS KOKKINI 8 ATTORNEY Patented May 30, 1972 9 Sheets-Sheet 6 BY M; fi

INVEN'IUR N'IKOLAUS KOKKINIS ATTORNEY INVENTOR NIKOLAUS KOKKINIS BY 2M ATTOR N IEY Patented May 30, 1972 9 Sheets-Sheet 7 Patented May 30, 1972 9 Sheets-Sheet 8 FIG. 11a

ATTORNEY Patented May 30, 1972 3,665,975

9 Sheets-Sheet 9 INVEN'IOR NIKOLAUS KOKKINIS ATTORNEY WEFT THREAD INSERTING MECHANISM FOR LOOMS The present invention relates to a weft thread inserting device or mechanism for shuttleless looms comprising a pair of gripper rods which are moved in reciprocating fashion and engage in the shed at the same distance.

In a weft thread inserting mechanism of this type, one gripper rod is mounted on each side of the loom and is inserted into the shed from the side and retracted again. Mounted at the front ends of the gripper rods are gripper heads which seize the weft thread to be inserted into the shed and guide it during the inserting operation or procedure. At that time the weft thread is drawn off of a large supply spool mounted outside of the shed.

Already known in the art are looms which place a weft thread that has been drawn off of a supply spool onto the thread holder of the gripper head in looped form, advance the weft thread to the center of the shed and there transfer it to the counter gripper, which latter will then stretch out the weft thread loop to the end of the shed. This weaving method incorporating the double insertion of weft thread has, however, the specific disadvantage that the thread which is brought up has twice the speed as compared to the gripper rod and that, as a result, it is stressed to an unnecessarily large extent at the thread reversing point of the gripper head. This may easily lead to the weft thread being torn ofi'. In accordance with a different prior method, the weft thread is no longer inserted in a complete loop over the entire width of the shed, but instead is introduced in looped form only up to approximately the center of the shed. Thereafter, the loop on the inlet side of the shed is opened and, after the thread transfer, the single now free loop end is completely drawn through the second half of the shed. The thread is thereby extended or stretched until ultimately the free end of the thread will project or hang over at the edge of the fabric. It is true that according to this method of inserting the weft thread only a single thread need be introduced, but this method does involve the same disadvantages and drawbacks which have been outlined hereinabove with respect to the insertion of a complete loop.

Also known are looms which avoid the disadvantage of the loop insertion by placing the weft threads individually into the shed. According to this method, a weft thread portion is brought to a clamping or gripping device, for example leaftype springs, being secured to the gripper head. This thread is advanced up to the center of the shed and then transferred to the counter gripper. The transfer of the weft thread from the transmitting means to the receiving means takes place automatically by virtue of a specific construction of the thread holder at the gripper head. For purposes of transferring the 'thread in the shed center, clamping hooks or clasps, for example,are used. The gripper which receives the clamped-in weft thread must, in tum,so hold or retain the weft thread after receiving in that, during the return movement of the grippers, the clamping effect and, respectively, the friction of the weft thread at the transferring gripper, i.e., at the transmitting means, is effectively overcome and so that the weft thread is drawn out of the clamping device of the transmitting means. This important requirement, however, is not satisfactorily met during the above-described automatic thread transfer with clamping springs. As a result thereof, weaving flaws recur time and again. Whether the reason be that the weft thread is not taken over or received at all in the center of the shed, or whether it is only incompletely drawn through the shed and lost by the receiving means too early in any event, the weft thread ends at the fabric edge become unevenly long.

A further significant disadvantage of such clamping springs resides in that, during the thread transfer, as mentioned, the weft thread is drawn off of the clamping device of the transmitting means under tension. This will result in an abrasion or wear and tear on the weft thread which not only has the effect of damaging the weft thread but in which case the wom'olf particles become unpleasantly noticeable by soiling the the spring clips. Due to the soiling, the clamping effect is considerably reduced, and under certain circumstances to such a degree that the entire clamping device breaks down. Additionally, these spring clamps further do not operate faultlessly at different thicknesses of the weft thread. Accordingly, it is not possible to process with this prior art method combinations of the weft threads of alternately coarse and fine threads with certainty.

It is therefore sought that this drawback be obviated by means of longer individual weft threads andby subsequently cutting off the thread ends being uniformly too long. This, however, increases the waste of weit material very considerably.

The present invention is based on the concept of constructing a weft thread inserting mechanism for shuttleless looms which are equipped with stationary supply spools for the weft thread and with a pair of gripper rods being moved in reciprocating fashion and engaging in the shed from both sides to approximately the same distance, wherein in the advanced or extended position of the gripper rods, for example in the center of the shed the weft thread is transferred or transmitted as individualthread from the gripper head of one gripper rod to the gripper head of the other gripper rod. In the present invention, the gripper heads are provided with clamping levers for the weft thread, which levers for the purpose of seizing and, respectively, releasing the weft thread are adapted to be positively actuated from the outside by means of operating levers coupled to the main drive of the loom.

' In order to allow for a gentle opening and closing of the clamping levers at the gripper rod heads, it is further proposed, according to another embodiment of the present invention, that the clamping levers be constructed in the shape of tongs and that a lever which is mounted oppositely with respect to the clamping part be equipped with a contact or bearing surface and, respectively, a running-up surface for the operating levers. The clamping part may be provided, for example, with a prismatic clamping surface and come to be positioned within a corresponding prismatic bed as a counterpart or seat.

Asa result of this measure of the forced control of the weft thread transfer it is now possible to accurately adjust or set the length of the weft thread so that, despite a rapid thread transfer, only a very short piece will remain as waste. Moreover, with this weaving method, a loop formation of the weft thread may be dispensed with entirely. By reason of this construction of the clamping mechanism, it is effectively assured also that very short thread portions are faultlessly held at the gripper head. It is further apparent from the present invention that threads having different thicknesses may be equally employed. Any possibly arising soiling within the clamping mechanism or device has substantially no influence upon the thread transfer and the weaving operation as such.

The present invention will be further explained hereinafter by reference to the accompanying drawings, wherein FIG. 1 is a simplified view of a loom;

FIG. 2 illustrates gripper heads with a clamping device or mechanism ofthe present invention;

FIG. 3 is another illustration of the clamping mechanism at an enlarged scale;

FIG. 4 is a cross-sectional view through FIG. 3;

FIG. 5 is a view of the gripper heads and control therefor at an enlarged scale;

FIG. 6 is a top plan view of the gripper heads with internal releasing levers;

FIG. 7 is a side view of the internal releasing lever control;

FIG. 8 is a side view of the external releasing lever control;

FIG. 9 is a sectional view of the loom according to FIG. 1 in a modified form thereof;

FIG. 10 is a difierent illustration of the construction according to FIG. 9 at an enlarged scale;

FIG. 1 1 illustrates schematically the operation of a loom according to FIG. 9,

FIG. 11a illustrates schematically the operation of a loom according to FIG. 1, and

FIG. 12 illustrates schematically the operation of the internal releasing mechanism.

FIG. 1 is a schematic view of a loom. Reference numeral 1 designates therein the frame of the machine. Mounted at the side thereof is the drive motor 2 and all the movements are derived from his central drive. The drive shaft 10, on which the eccentric 11 is mounted, is driven by the common gear 12 via the main drive shaft 13, and the

gripper rods

17, 18 are moved to and fro by means of the gripper rod gear 19. The gripper rod 17 is provided at the front end or end face thereof with the gripper head 21 and the gripper rod 18 carried the gripper head 20. The two gripper rods with the gripper heads thereof have been shown in full lines in the retracted position thereof when they are outside of the shed and in phantom in the extended position thereof approximately in the center of the shed. The supply spool container 3 receives the weft thread supply spools 4. Positioned in the center of the machine is the comb or reed 5 which is driven by the arms 6 of the reed shaft 7 and oscillated back and forth. Secured to this reed shaft 7 are also the drive elements for the control of the gripper heads, such as the roller lever 8 and the supporting arm 9, respectively.

The clamping devices or means at the gripper heads 20 and 21 which have not been further illustrated herein are controlled in the center of the shed by means of the control mechanism and outside of the shed by means of a corresponding releasing mechanism 16. The drive elements for the control mechanism 15 are positioned on the reed shaft 7, as has already been mentioned hereinabove, and include the roller lever 8 and the supporting arm 9. The drive thereof is effected by means of the eccentric disc 11, as will be more fully described hereinafter. The releasing mechanism 16 may be driven in a similar manner. In this case it has been assumed that it is actuated by a shaft-sliding gear 14.

In the case of the loom which has been shown here as one embodiment, it has been assumed that the weft thread is inserted at all times only from the left side as an individual thread. Accordingly, the left gripper head 21 may be designated as transmitting means and the right gripper head 20 may be designated as receiving means." The construction of the gripper heads has been shown in further detail in FIGS. 2 to 5. During the weaving operation, the weft thread is offered to the left gripper head, the transmitting means 21. For this purpose, the releasing mechanism 16 on the left side of the machine will be actuated and controls the clamping device at the transmitting means 21. The clamping device is opened for a short period of time and then closed again after it has seized the weft thread which had been offered thereto. Once the weft thread has been conveyed by the transmitting means 21 up to approximately the center of the shed, the control mechanism 15 will actuate the clamping devices of the transmitting means 21 and the receiving means 20, and the weft thread will be transferred from the transmitting to the receiving means. During the return of the gripper rods, the receiving means 20 will pull the weft thread completely through the shed. When the receiving means 20 has arrived outside of the shed, the clamping device at the receiving means 20 will be opened on the right hand side of the machine by the releasing mechanism 16, and the weft thread end is released.

It is apparent from FIGS. 2 and 3 how the gripper heads 20 and 21 together with the clamping devices or means thereof are constructed. The clamping devices consist of the doublearmed clamping levers 22 and 23, respectively, which are adapted to be pivoted in each case about the bearing 24 in a scissor-like manner. The arm of these clamping levers facing away from the gripper tip is provided with a contact or bearing surface and, respectively, a running-up

surface

22a and 23a, respectively. A control lever will come to rest against this running-up surface, as will be described in further detail hereinbelow, and pivots the arms downwardly, and hence the arm pointing toward the gripper tip pivots the clamping

portion

22b and 23b respectively of the clamping levers upwardly. As a result thereof the clamping device will be opened at the two gripper heads 20 and 21, respectively. The position of the clamping

parts

22b and 23b shown in phantom illustrates the position thereof in the opened condition. In this position, the

weft thread is either inserted or taken out of the clamping device. It is also apparent from this showing how the clamping spring 25 is positioned and engages at the projection 26 in order to retain the clamping levers 22 and 23 in the closed position thereof due to spring pressure. This spring 25 is constructed as a simple leaf-type spring and has the effect that, during the insertion of a thicker weft thread, a stronger pressure is correspondingly exerted upon the clamping point. This becomes significant in view of the fact that a thicker thread has a considerably greater mass and might therefore be lost under certain circumstances during the rapid drawing of the weft thread through the shed if the same pressure for all thread thicknesses were exerted upon the clamping device.

FIG. 3 is a view at an enlarged scale of the clamping device at the gripper head 21. Also distinctly apparent from this figure is the construction of the thread fork 28 at the gripper head 21. Since the left gripper head 21, i.e., the transmitting means, is involved in this case, the thread fork 28 needs to be effective only in one direction. The positioning or support of the thread at the counter gripper head 20, i.e., the receiving means, with the thread hook 29 is shown in FIG. 2.

FIG. 4 is a cross-sectional view through FIG. 3 at the point indicated by the arrow. The clamping device has the shape of a prismatic bed, as is clearly visible in the cross section. The clamping part or portion, for example 23b, has a prismatic configuration at the lower end 31 thereof. A corresponding prismatic bed 27 in the gripper head 21 serves in this case as a counterpart and a support or seat. The prismatic bed is constructed as a plate and is secured to the gripper head 21. It also comprises the recess already mentioned above of the thread fork 28 at the transmitting means 21 and, respectively, the thread hook 29 at the receiving means 20. This particular type of construction of the clamping device is important because in this case the clamping length for the thread is considerably increased and the arrangement is practically equal to a looping or winding or a thread about a cylinder. It is thereby effectively possible that even a very short thread portion can be perfectly retained. The clamping device at the counter gripper head, i.e., at the receiving means 20, is correspondingly constructed. This provision and construction of the clamping devices assures the secure clamping and unimpeded release of the weft thread. The disadvantages and drawbacks outlined hereinabove in connection with the prior art spring clamps and the fiat tong-like clamping devices will thus no longer arise.

FIG. 5 shows a cut-out portion or section of FIG. 1, namely the control mechanism 15 for the clamping devices at the gripper heads. This mechanism includes the supporting arms 9 and the roller levers 8. The construction and operation of the control mechanism will be explained in further detail hereunder in connection with FIGS. 5 and 6.

FIG. 6 is a side view of the control mechanism 15. The supporting arms 9 are clamped onto the comb or reed shaft 7 and concomitantly execute or carry out the pendulum or oscillating movement of the reed. They are provided at the ends thereof with a connecting rod 32 which is rotatably mounted in the supporting arms within the bearing 9a. Clamped onto the connecting rod 32 are the control levers 34, or they are otherwise secured thereto in a manner preventing relative rotation. During the control operation for the weft thread transfer, these control levers 34 will come to be positioned from above onto the supporting or

contact surface

22a and 23a, respectively, of the clamping levers 22 and 23, respectively.

As a further significant structural element, the control mechanism 15 also includes the roller lever 8. It is rotatably mounted on the reed shaft 7 and carries a roller 8a which, under the action of a return spring 36, will come to be placed against the constantly rotating eccentric disc 11. By reason of the relative rotating movement of the roller lever 8 on the reed shaft 7, which arises during the rotation of the eccentric disc 11, the movement is transferred by way of an intermediate lever 8b to one of the control levers 34. The other control lever 34 is equally concomitantly moved by the simultaneously rotating rod 32. It is understood that the intermediate lever 81; need not be directly connected to the control lever 34, as has been illustrated herein for the sake of simplicity, but may instead effect a rotating movement of the connecting rod 32 also in any other fashion, and hence an up-and-down movement of the control levers 34. It is readily apparent that with the aid of the particular construction of the eccentric disc 11 and the control mechanism 15, the desired control times or periods for opening and closing the clamping devices during the weft thread transfer may be precisely maintained, or also may be modified as desired, if such is necessary.

The mechanical coupling of the roller levers 8 with the reed shaft 7, on the one hand, and the arrangement of the supporting arms 9 on the other hand has the result that the control mechanism causes the control levers 34 to be in the shed precisely at the predetermined period of time or moment for purposes of actuating the clamping devices at the gripper heads. A stop member 40 with a setscrew 41 allows for a precise settingof the rotary movements and, respectively, of the spring deflection or travel stroke for the roller lever 8.

FIG. 7 is a top plan view of the gripper heads and 21 with the internal control mechanism 15. This figure shows the position of the gripper heads 20, 21 immediately prior to the transfer and acceptance or reception of the weft thread 30. The left gripper head 21 moreover comprises an additional guide bar 33 which holds the weft thread at the reversing point in such a manner that an approximate loop will be formed and the counter gripper head 20 is adapted to accept and clamp in the thread 30. Only after the weft thread has been accepted by the receiving means 20 will the clamping device also open at the left gripper head, i.e., the transmitting means 21, and the thread 30 will be inserted or placed in the shed due to the retraction of the right gripper rod 18.

This figure illustrates once more the arrangement of the supporting arms 9 with the connecting rod 32 thereof and the control levers'34 being securely clamped thereto. Also shown therein is the connection of the intermediate lever 8b to the control lever 34. The ends of the control levers 34 will come to be placed from above onto the contact or bearing surfaces and the running-up

surfaces

22a and 23a, respectively, thus opening the clamping devices at the gripper heads 20 and 21, respectively. During this movement, the control levers 34 extend for a brief period of time and from the outside through the warp threads into the shed.

The positive control of the clamping devices in the center of the shed proceeds in the following manner. In the present example, it has been assumed that the control mechanism 15 is actuated only by means of a single eccentric disc 11. For this reason the two control levers 34 are moved simultaneously in the manner described above. The control of the

clamping devices

22, 23 at the gripper heads 20, 21, however, takes place asymmetrically so that the actual times for the opening and closing of the clamping devices at the transmitting gripper head 21 and at the receiving gripper head 20 are chronologically shifted. When the opening or closing operation of one clamping means takes place while the corresponding gripper head stands still, the control levers 34, while being lowered,

. press down upon the contact or bearing

surface

22a and 23a,

respectively, and thus open the clamping device, and respectively they will close the latter when the control levers 34 are being lifted up once again. The surfaces 22a and 230 may be effective, however, also as running-up surfaces when one gripper head slides under an already previously pressed-down control lever 34 and, respectively, is pulled out from under the control lever. The receiving means 20 leads the transmitting means 21 with regard to time and achieves the most advanced or farthest extending position thereof within the shed ahead of the transmitting means 21. The. clamping device 22 at the receiving means 20 is opened by means of the control levers 34. Only thereafter will the transmitting means 21 which carries the weft thread arrive at, or reach, the corresponding point in the shed and guide the weft thread into the clamping device 22 of the receiving means 20. Thereupon a brief parallel run of both gripper heads takes place at which time the receiving means 20 already runs backwards again and recloses the clamping device 22 thereof. The transmitting means 21 will still continue in the forward movement thereof for a short path. During this parallel run or travel, the running surface 23a of the transmitting means 21, coming from the left under the already pressed-down left control lever 34 is traveling so that also for the transmitting means the clamping device 23 is opened and the weft thread can be transferred. At the end of the parallel traveling path, the two gripper heads become separated and also the transmitting means begins it return movement. The control levers 34 are now back in the position of rest thereof so that the clamping devices both at the receiving means 20 and at the transmitting means 21 are closed. The weft thread has been transmitted from the transmitting means 21 to the receiving means 20 and has been securely clamped in at the latter. The shifting or operating times for the clamping devices and the movements of the gripper rods and, respectively, gripper heads are accordingly displaced in phase to a certain extent. The phase displacement, i.e., the lead of the gripper rod 18 with the receiving means 20 as compared to the gripper rod 17 with the transmitting means 21 takes place in a simple manner, for example by correspondingly designing the gripper rod gear 19 on both sides of the loom. The phase displacement for opening and closing the clamping devices is effected by a chronologically shifted or displaced arrival of the gripper heads, as has been described above, under the simultaneously actuated control levers 34.

FIG. 8 is a side view of the external releasing mechanism 16. As has already been described, the external releasing mechanism 16 is driven separately and mounted on both sides outside of the shed. The operation thereof is the same in principle as that of the internal control mechanism 15. Here again, a sequence of movements is transferred via an eccentric 11a to a control lever 35 which acts upon the clamping lever 22 and, respectively, 23 by virtue of spring tension. A bolt or tension spring 36a presses the control lever 35 downwardly onto the running-up

surfaces

22a and 23a, respectively, of the clamping levers 22 and 23 as soon as the eccentric 11a renders it possible. The releasing mechanism 16 on the left-hand side of the machine controls the opening of the clamping device 23 at the transmitting means 21 for the period of time during which the weft thread being drawn OR the supply spool is offered to the transmitting gripper head 21 by means of a thread feeding device (not shown). In an analogous manner, the releasing mechanism 16 on the right-hand side of the machine will become operative only after the weft thread has been pulled completely through the shed by the gripper head 20 and must be released. As far as the transfer'and acceptance of the weft thread approximately in the center of the shed are concerned, the releasing mechanisms 16 have no significance. The releasing mechanisms 16 outside of the shed may be constructed in the most diversified manner. Essential is here again particularly the fact that the control levers are moved by gear elements, for example eccentric discs, only when the clamping devices at the gripper heads are intended to be actuated.

In the embodiment of FIGS. 1 and 5, respectively, a common eccentric disc is provided for the control mechanism 15 mounted in the center of the shed. The time difference for the control of the two control levers 34 is attained by an asymmetrical sequence of movements of the gripper rods and a thread transfer during a brief parallel travel of both grippe heads and gripper rods, respectively.

FIG. 9 shows a modified embodiment relative to this construction according to which two

separate control mechanisms

15 and 15a are present for the control of the clamping devices at the gripper heads 20 and 21. Each control mechanism is controlled by a separate eccentric disc 11 and 11b, respectively. The position of the two gripper heads 20 and 21 as shown in phantom is merely intended as an approximate indication and does not correspond to the precise position at the time of the thread transfer. The connecting rod 32 on which the two control levers 34 were positioned in accordance with FIG. 1 is now divided into two parts both of which have been designated with reference numeral 32a.

The construction of FIG. 9 is again shown in FIG. 10 at a slightly enlarged scale. Visible to the right is the control mechanism for the receiving gripper head and at the left the control mechanism 15a for the transmitting gripper head 21. Each control mechanism consists of two supporting arms 9 and rotatably positioned at the end thereof within the bearing 9a is the connecting rod 32a. The control lever 34 is again securely clamped in on the connecting rod 32a. Shown between the two supporting arms 9 is the roller lever 8 with the roller 8a. By means of the latter, the oscillating movement which has been initiated by the eccentric discs 11 and 11b, respectively, is further transferred via the intermediate lever 8b to the connecting rods 32a, as has been described hereinabove. Illustrated next to the main drive shaft 10 to the left and right are side views of the two eccentric discs 11 and 11b, by way of example, in order to indicate that the eccentric discs may have a phase displacement and may be constructed in different fashion, if desired. The curved form of the eccentric disc as shown in the drawing is merely intended to supply an impression of the possibly existing conditions; it does not correspond to the requirements as they arise during actual operation. It is readily apparent that due to the choice of the curve shape of the eccentric and the rotation; or in other words, the phase displacement of the two eccentric discs with respect to each other, any desired control time may be set and varied. The two gripper heads, the transmitting means 21 and the receiving means 20, also are shown in this figure. By the position of these two gripper heads, the leading characteristic of the receiving gripper head 20 is indicated.

The thread transfer takes place in the following manner. As soon as the receiving gripper head 20 has arrived in the foremost position thereof, the control lever 34 is pressed upon the running-up surface 220 of the clamping device by means of the control mechanism 15, and the clamping device is thereby opened. The receiving means 20 is thus ready to receive and accept the weft thread. Slightly later, the transmitting means 21 reaches its foremost position and guides the weft thread into the opened clamping device of the receiving means 20 since in the foremost position thereof the two gripper heads will slightly overlap each other. Thereupon the control mechanism 15 closes the clamping device 22 at the receiving means 20 once again and the weft thread is securely clamped in. Only at this time will the opening of the clamping device 23 at the transmitting means 21 take place by means of the control mechanism 15a. The receiving means 20 is then retracted and carries along the clamped-in weft thread. Once the weft thread is pulled out of the transmitting means 21, also the clamping device 23 of the latter is once again forcibly closed and the transmitting means 21 is retracted. The thread transfer thus takes place while the two gripper heads 20 and 21 are stationary in a manner such that at no time are the two

clamping devices

22 and 23 opened simultaneously. The two control levers are actuated at that time individually and separately. The thread is thereby firmly held at all times and can never be lost during the transfer thereof. The thread transfer works perfectly also if different thicknesses of weft threads, i.e., very thick and very thin weft threads, are intended to be inserted alternately. Even in case the weft threads project or overlap only by a short distance, these short ends are securely grasped and held by the clamping device. It is therefore possible to accurately measure the length of the various weft threads and thus attain a considerable reduction of the waste relative to the weft thread material.

Another advantage of this construction resides in the fact that the lead of the one gripper head as compared to the other may be shorter than in the embodiment of FIG. 1, which means that the mutual gear displacement can be considerably reduced. The unbalance of the entire machine thus becomes smaller and the operation thereof smoother. Additionally, the

times needed for the transfer of the thread are considerably shortened, particularly because no parallel operation of the two gripper heads is required any longer. Due to the omission of the parallel travel, which represents a type of relay race for the two grippers, there is achieved an increase of the usable weaving width about the length of the path of the parallel travel, provided the stroke of the gripper rods remains the same.

FIG. 11 schematically illustrates, with reference to the embodiment of FIGS. 9 and 10, the course of the thread transfer as described above in 10 different positions. In the position one, the external releasing mechanism 16 at the transmitting means 21 opens the clamping device, and the weft thread is inserted into the transmitting means 21 by means of a thread feeding device. In positions two and three the weft thread is clamped into the transmitting means and the advance movement of the gripper heads has begun. Here the lead of the receiving means 20 has been indicated. The thread transfer proper at the stationary position of the advanced gripper heads is illustrated in positions four to eight. It is evident that at no time will the clamping devices of both gripper heads be open simultaneously. Position 9 shows the pulling-through of the weft thread during the return movement of the gripper heads. In position l0, both gripper heads have left the shed and the receiving means 20, forcibly controlled by the external releasing mechanism 16, releases the weft thread. Position 1 I already shows once more the beginning of the new cycle.

FIG. 11 also illustrates that the left control lever 34 is actuated independently of the right control lever. At that time, the receiving gripper head has the positions four to seven, while the transmitting gripper head 21 has the positions five to eight, in the position of rest thereof.

FIG. 11a schematically illustrates, with reference to the embodiment of FIG. 1, the course of the thread transfer as described above in 10 different positions. From this figure, it is evident that in the positions five to seven, both grippers, i.e., the receiving means 20 and the transmitting means 21, extend in a parallel manner for a portion of the travel thereof and transmit the thread during this parallel course or path. In this case, the control levers 34 are so coupled to each other that they execute their movements simultaneously. They are pressed down for the entire duration of the positions five to seven. The opening and closing of the clamping means is effected partially by depressing the control levers onto the contact or bearing surface and partially also by virtue of the fact that the grippers, with the running-up surfaces thereof, are slid under the pressed-down control levers 34 and then retracted.

The sequence of operations of the control levers is shown schematically in FIG. 12. Apparent therefrom is the position of the supporting arms 9, of the intermediate lever 8b and of the control lever 34 for different periods of the weaving operation. The showing of the various positions corresponds approximately to positions one through 10 in FIG. 11. Also shown therein are the positions of the eccentric disc 11 and of the roller 8a as well as the positions of the reed 5 and of the gripper head 20, corresponding to the various positions. It is apparent that the control lever 34 is initially situated outside of the shed (positions one through three). Only shortly before the gripper head 20 attains the advanced position thereof in the center of the shed will the control lever 34 be introduced from the outside through the warp threads of the lower shed into the shed (position four). The guide member 20 is mounted on the gripper head and slides along the reed 5. As soon as the control lever 34 actuates the clamping means, the gripper head will be securely pressed with its guide member 20 against the reed 5. Vibrations during the transfer of the thread are thereby effectively supressed and the position of the gripper head is fixed and centered. Guide members of this type are present both on the receiving gripper head 20 and on the transmitting gripper head 21. For purposes of the thread transfer, the control lever 34 presses the contact surface of the clamping device downwardly for a short period of time and is again lifted up thereafter into the previous position (positions tive and six). After the gripper head 20 has started its return movement, the control lever 34 is again pulled out of the shed (positions seven to 10). For the purpose of fixing the wefi thread, the reed 5 and together therewith the supporting arms 9, the intermediate lever 8b and the control lever 34 are pivoted. At that time the roller 8a lifts off the eccentric disc 11. This sequence of movements is valid generally for the two above-described embodiments of the weft thread inserting device.

ln FIGS. 1 and 9, the thread feeding device between the supply spool 4 and the gripper head 21, which is actually necessary, has not been shown. In'order to render it possible that the weft thread and several, for example differently colored weft threads, be selectively offered or supplied to the gripper head 21, a specific interstice is needed between the edge of the fabric and the gripper in the retracted position thereof, which interstice is not required on the counterside, i.e., on the receiving side of the machine. As a result thereof, the center of the fabric sheet or width is positioned slightly offset in the direction toward the other side of the loom as compared to the symmetrical stroke of the

gripper rods

17 and 18 and the gripper heads 20 and 21. It is possible in this manner that, despite the lead of the gripper head 20, both gripper heads 20 as well as 21 are retracted substantially simultaneously out of the shed. This constitutes a marked advantage. Without this particular measure it would be necessary to wait until the trailing gripper head left the shed in order to close the latter and cast on the weft thread, which would, however, result in a loss of time. If, on the other hand, the closing of the shed were initiated before the trailing gripper 21 had completely left the shed, damage to the warp threads would be produced. All of these disadvantages are avoided by means of the aforementioned displacement of the entire width of fabric.

The release of the drawn-through weft thread by the receiving gripper head 20 takes place advantageously by means of the releasing mechanism 16 being mounted laterally with respect to the shed and at a time when the binding-off of the fabric edge clearly prevents any jumping back of the weft thread. In case of weft thread material which is not delicate in this respect, the release obviously can take place at an earlier time.

A further advantage of the construction proposed in FIG. 9 as compared to FIG. 1 resides in that the transmitting gripper head 21 cannot by mistake automatically be opened. In case of flaws in the shed, for example so-called nests, it is possible that the gripper rod is lifted during the advance thereof so that in the raised position thereof the running-up surface 23a of the clamping device erroneously strikes too early upon the control lever 34 and that therefore the weft thread will no longer be clamped in but is possibly lost. In other words, the thread slips out of the transmitting means before the thread transfer has actually been effected approximately in the center of the shed.

Due to the positive control of the loom, it is now possible to shorten the working cycles or strokes at the machine, whereby an increased weaving velocity is achieved. In addition thereto, it is possible in a simple manner, with the aid of the special clamping device proposed by the present invention to also alternately utilize weft threads having different thicknesses, i.e., irrespective of whether a single thread or weft thread combinations having different thicknesses are intended to be processed. Furthermore, any possible soiling of the clamping device cannot prevent the weft thread from being securely held. Also, the control lever affords the advantage of representing an additional safeguard of the gripper rods against breaking-out and of effectively suppressing any possibly arising vibrations. The entire weaving process may be carried out at an increased speed by virtue of the automatic control, i.e., higher weaving speeds are attainable. By reason of the perfect thread transfer between the two gripper heads and the secure positioning and holding of the thread until it is completely drawn through the shed, weft thread ends having a uniform length are obtained at all times at the fabric edge. The projecting thread ends may a priori be dimensioned short so that the waste relative to the weft thread material is reduced to a minimum.

In connection with the present invention it is of particular advantage that the wefl thread, during the transfer thereof, is not pulled out of the clamping device of the transmitting means under tension, but that the thread is transmitted or transferred without tension. Any damage to the wefi thread or a troublesome abrasion are thereby effectively eliminated. The control levers for actuating the clamping devices are either positioned laterally with respect to the shed, or extend into the shed, approximately to the center thereof, only for a brief period of time. Accordingly, they do not adversely affect the remainder of the operations.

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is 1. A weft thread inserting device for a shuttleless loom in which successive sheds are formed comprising a pair of gripper rods having gripper heads mounted on the ends thereof with each gripper head including a clamping means, the gripper rods being mounted for reciprocating movement into a shed, one of said clamping means being adapted to clamp a weft thread at one side of the shed and draw it into the shed center to be transferred from said one clamping means to the other and drawn through the other shed half, and each of said clamping means on the gripper heads being adapted to be positively actuated by pivotal means which penetrate the shed from he exterior thereof about at the shed center.

2. A weft thread inserting device according to claim 1 in which the clamping means comprises clamping levers actuated by control means including levers coupled to the main drive of the loom.

3. A weft thread inserting device according to claim 2 in which the clamping levers are tong-like double-armed levers and the lever arm opposite to the clamping portion includes a bearing surface and a running-up surface for the control levers.

4. A weft thread inserting device according to claim 2 including roller levers connecting the control levers with the reed shaft of the loom and cam means on the loom drive shaft for effecting the movement of the control levers.

5. A weft thread inserting device according to claim 2 including additional control lever means mounted on each side of the loom laterally outside of the shed for purposes of positive control of receiving the weft thread offered to one clamping means and, respectively, for the purpose of releasing the weft thread pulled through the shed by the other clamping means.

6. A weft thread inserting device according to claim 5 including separate control and releasing means with separate cam disc drive for each of the control levers and additional control lever means positioned approximately in the center of the shed and laterally outside of the shed, respectively.

7. A weft thread inserting device according to claim 2 including spring means biasing the clamping portions into engagement.

8. A weft thread inserting device according to claim 2 including common cam means coordinated to the control levers, the release of the weft thread by one clamping means and the seizing thereof by the other claiming means being effected by an asymmetrical advance of the gripper rods.

9. A weft thread inserting device according to claim 2 including separate control means each being separately and independently controlled by separate cam means and being coordinated to the control levers.

10. A weft thread inserting device according to claim 2 in which the clamping portions of the clamping means are prismatically shaped elements forming the upper portions of the clamping means, the upper portions in the closed position thereof engaging prismatic bed counterparts rigidly mounted on the gripper heads.

Claims

1. A weft thread inserting device for a shuttleless loom in which successive sheds are formed comprising a pair of gripper rods having gripper heads mounted on the ends thereof with each gripper head including a clamping means, the gripper rods being mounted for reciprocating movement into a shed, one of said clamping means being adapted to clamp a weft thread at one side of the shed and draw it into the shed center to be transferred from said one clamping means to the other and drawn through the other shed half, and each of said clamping means on the gripper heads being adapted to be positively actuated by pivotal means which penetrate the shed from he exterior thereof about at the shed center.