Loom dobbies

Abstract

Claims

United States Patent 72] Inventor Thomas l-llndle Blackburn, England [21 Appl. No. 759,653 [22] Filed Sept. 13, 1968 [45] Patented Dec. 8, 1970 [73] Assignee llindle, Son 8: Company Limited Blackburn, England I 32 Priority Oct. 3, 1961 [33] Great Britain [54] LOOM DOBBIES 9 Claims, 5 Drawing Figs. [52] US. Cl. 139/77 [51] lnt.Cl. D03c H12 [50] Field ofSearch 139/77, 76. 180. 66, 67. 55 [56] References Cited UNITED STATES PATENTS 1,886,133 11/1932 Staubli 139/77 2,049,090 7/ 1936 Staubli 139/77 2,377.8,00 6/1945 Mascarenhas 139/55X 2,687,751 8/1954 Moir 139/77 3,144,883 8/1964 Short 139/55 FOREIGN PATENTS 12,662 0/1890 Great Britain 139/77 1,069,915, 5/ 1967 Great Britain 139/66 Primary Examiner-James Kee Chi Attorney-Roberts, Cushman and Grover ABSTRACT: In a loom head-motion or dobby of the Knowles-type, an electrohydraulic or electropneumatic relay is provided whereby the vibrator lever is caused to pivot to engage the vibrator wheel caused thereby with one or other of the driving cylinders according to pattern requirements. A toggle lock is created at each extreme position of the vibrator lever to maintain a positive drive engagement between the vibrator wheel and the selected driving cylinder, and a timing switch ensures that the relay is inoperative in pivoting the vibrator lever whilst the vibrator wheel and a driving cylinder are drivingly engaged. LOOM DOBBIES This invention relates to gear dobbies, also known as headmotions, of the Knowles-type," of which the principle of operation and customary construction are as follows, Corresponding in number to the heald shafts to be actuated, the jack levers, usually of bell crank form, swing on a common fulcrum bar supported by the framework, and are connected to the heald shafts by a series: of streamers, pulleys and tieups. Each jack lever is linked by a connector (or connecting rod) to a crankpin on'a vibrator wheel (or crank gear) which is adapted to rotate 180, between stops, first in one direction and subsequently in the other, thereby lifting or lowering the heald shaft connected to it. Each vibrator wheel rotates on an axle pin fixed in a horizontally disposed vibrator lever, corresponding number of which levers also swing on a common fulcrum bar supported by the framework. The vibrator wheels are displaceably located between two partly toothed driving cylinders, which rotate continuously in opposite directions at loom crankshaft speed. The vibrator wheels, through the medium of the vibratorlevers, are independently lifted or lowered to bring them into meshing distance with either the top or the bottom cylinder. The rim of each vibrator wheel has two equal series of teeth with two diametricallyopposite gaps between them. The , larger gap is equal to four-or five teeth, and when turned cylinder to rotate freely without further engagement with the vibrator wheel. The smaller gap, which is equal to only one tooth, enables theleading tooth on the engaging cylinder to enter into mesh after the vibrator wheel has been set in meshing distance. The jack lever is retained in its extreme positions by a toggle lock formed by the crank radius and the connector as the vibrator wheel completes its half-turn first in one direction and subsequently in the other. i In the known constructions, the vibrator lever and its vibrator wheel are lifted by a bowl on the pattern chain, whereas tube allows them to descend by gravity; Thus thevibrator wheel is lifted by a bowl so as to mesh with the top cylinder, with the.effect that the vibrator wheel is rotated through a half-turn, during which its crankpin and connector swing over the jack-lever and lift the healdshaftThis is then retained in that position by the aforesaid toggle lock as long asthe pattern chain presents a succession of bowls to maintain the vibrator lever and its wheel in such raised position. Conversely, a tube on the pattern chain allows the vibrator lever and its wheel to descend so as to gear with the bottom cylinder, with the effect that the vibrator wheel is rotated through a half-turn inthe opposite direction during whichthe jack lever swings back and lowers the heald shaft. This is then similarly retained in that position by the toggle lock as long as the pattern chain presents a succession of tubes. A characteristic feature of all conventional Knowles-type head-motions is the provision of a cam and spring actuated lock knife, which after their selection by the pattern chain, en gages the outer ends of all the vibrator levers and locks them more or less rigidly in their respective up or down positions, so as to hold the gears correctly in mesh while the cylinders are turning the vibrator wheels through 180. During each cycle, the lock knife is first withdrawn from all the vibrator levers, thereby freeingthem'to enable the pattern barrel to be turned to make a new selection in the above described manner, after which the lock knife goes in again to lock the lever ends, all of which operations must be completed down movements of the vibrator levers characteristic of such purely mechanical devices, and, furthermore, because of the relatively. short time available for their operation, that is to say, the time in each cycle when the movement of the vibrator levers is not restrained by the lock knife. i ly mechanical means, it becomes necessary also to divide the pattern chain into two parts, each such part of the pattern chain being built-in with that part of the head-motion it controls. This arrangement raises the practical problem of maintaining the two pattern barrelsfand their respective chains in exact synchronism in all circumstances. For example, it is occa sionally necessary to rotate the loom crankshaft, a revolution at a time, when unweaving and removing weft from the cloth in order to correct a weavingfault. The gear mechanism of the Knowles head-motion cannot be continuously rotated in the reverse direction,-e.g., by reversing the entire loom, including head-motion and pattern barrel, as: is possible with certain alternative dobby mechanisms. ltis therefore necessary, in the above described circumstances, to drive the loom and Knowles head-motion in the normal direction of rotation, while reversing the pattern barrel (or each barrel), so that it turns backwards. Such temporary reversal involves declutching and clutching operations, during which the two pattern barrels are liable to get out of step, and thereby disorganise, not only the shedding, but also the shuttle boxes and the picking. The object of the present invention is to provide improvements in relay mechanism for the actuation of the vibrator levers in a Knowles-type head motion, whereby the said vibrator levers make no redundant movements but are positively displaced in either direction and are then effectively retained in such selected operative positions during the meshing of the gears, therebydispensing with the customary lock knife and affording a relatively longer period for the setting movements of the vibrator levers and wheels, and whereby, furthermore, the two parts of a Knowles-type headmotion, located at opposite ends of a wide loom, are effectively controlled by a single pattern barrel and chain located at one end of the loom thereby ensuring exact synchronism of the two parts of the head-motion in all circumstances. Thus, according to the present invention the vibrator levers and their wheels are set, i.e. positively raised and lowered, and then retained iri such selected positions, by means of a series of electrohydraulic or electropneumatic relays. According to a further featureof the invention, a timing switch driven by a cam rotating at crankshaft-speed is provided, whereby any manipulation of the pattern switches, whether intentional or not, while the gears are turning in mesh has no effect on the selection already made, or on the mechanism itself, until that selection has been fully implemented. According to a still further feature we'provide a manual shaft-levelling control functioning incombination with the above-mentioned timing switch, whereby after a further revolution of the loom crankshaft all the heald shafts my may be simultaneously brought to their top positions, such manual control being operable at any point in the cycle without derangement of the mechanism, and becoming effective only as and when the said timing switch closes shortly after the engaged gearshave run out of mesh. The invention will now be described further, by way of example only, by reference to the accompanying drawings in which: FIG. 1 shows the mechanism of the conventional Knowles head-motion with certain omissions and additions to adapt the mechanism in accordance with one form of the invention, in which the vibrator levers are set into one or the other of their operational positions and locked or retained therein by means of electrohydraulic or electropneumatic relays, the slave cylinders of which directly actuate the said levers; FIGS. 2 and 2A show a modification in which the said electropneumatic relays actuate the vibrator levers through intermediate linkageswhich provide a toggle lock at both ends of i the piston stroke;,and ' shaftstnot shown) throughtop and bottom streamers connections such as Tand B .,At hinge pin 3, each jack lever is linked by connector Qtocrarikpinfia fixed at a common radius in vibrator wheel 5, .whichwheel rotates on axle pin 5a fixed in the horizontal ,vibratorlever-6, arranged to swing on the common fulcrum; bar 7. These fulcrum bars 2 and 7, also the through bar 12, aresupported by the frames (not shown). The ivibratorwheels5,are rotated in the usual manner, a half turn at a time in one direction and subsequently in the other, by their meshing altemately with the partly toothed driving cylinders 8 and19, which rotate continuously in opposite directions. The vibrator lever 6 is adapted to be raised orlowered'suflicientlyto set its vibrator wheel 5 in meshing distance with either the top cylinder 8 or the bottom cylinder 9,. and as alrea dy explained, this setting operation is usually performed by the direct'but negative action of the pattern chain,- followed up by the engagement of a lock knife, the purpose of whichis to hold the vibrator wheels in correct mesh with their selected driving cylinders, while the heald shafts are being lifted or lowered. f In the arrangement illustrated however, the customary lock knifeand its cam, together with the timing restrictions these impose on the setting operations, are discarded, and the vibrator levers and'their wheels are set, i.e., positively raised and lowered, and then retained in such selected positions, by means of a series of electrohydraulic or electropneumatic reIaysTheusuaI .lock knife,jthus superseded, does not appear in FIG. 1, in which also the location of the pattern chain barrel is not conditioned by its usual direct actuation of the vibrator levers. i As shown in FIG. 1, each vibrator lever 6 is positively and precisely displaced from one operational position to the other, and then retained in such, set position for as long as required, by the direct action of a doubleacting slave cylinder 11, any number of wh'ichlare flexibly anchored to the through-bar 12, while each pistonrod 11a is connected by pin 6a to its coacting vibrator lever 6, preferably at its extreme end, or maximum radius, as'shown in FIG. 1. External stops may be provided or, altematively, the movement of each vibrator lever may belimited by the slave cylinder piston abutting against the cylindercover at each end of the stroke. The vibrator levers are thus rendered independent of gravity for their operation, and, if preferred, they may be vertically disposed with equal effectiveness, as mentioned later herein. The slave cylinders 11 are powered by any suitable pressure medium, such as hydraulic fluid or compressed air. The action of each cylinder 11 is governed by a two-position piston-valve 13, which itself is controlled by electric solenoids l4 and 15, in such manner that when solenoid is momentarily energized, the piston valve shoots fully'over to its lifting side, and remains there until solenoid 14 is next momentarily energized, whereupon the piston valve shoots back to its lowering position, and similarly remains there until solenoid 15 is again energized, and'so on. L The said two solenoids 14 and 15 of each 'valve 13 are selected for energization by the pattern switch 16, which is one of the single-pole changeover type, and is operated by the patternchain 18, driven by the barrel 19, which is rotated in unison with the driving cylinders 8 and 9 in the usual manner, but in the present case may be located in any convenient position on the loom, As will be apparent, the loads imposed on the pattern chain and its driving mechanism when merely required to actuate a series of microswitches are insignificant in comparison with those, involved in lifting, usually at a mechanical disadvantage, thevibrator levers and wheels. A bowl on the pattern chain lifts sensing lever 17 and closes contacts U in the circuit of solenoid l5,whereby, when this is momentarily energized, the piston valve 13 shoots over so as to cause the slave cylinder 11 to raise the vibrator wheel 5 into meshing distance with the top cylinder 8, with the effect that in due course the heald shaft is lifted. 5 Conversely, a tube on the pattern chain lowers sensing levers 17 (under the action of its own weight aided by a spring) and closes contacts D in the circuit of solenoid 14, whereby, when this is momentarily energized; the piston valve 13 shoots back so as to cause the slave cylinder to lower the vibrator wheel 5 into meshing distance with the bottom cylinder 9, with the effect that in due course the heald shaft is lowered. The parallel circuit of all the pattern switches such as 16 (of which there is one for each shaft to be actuated) are controlled by a master timing switch 20, the contacts of which are opened by a spring and closed by the cam 21, which rotates in unison with the driving cylinders 8 and 9. This timing switch is preferably arranged to close shortly after the vibrator wheels have completed their half turns, and to remain closed while the cam rotates through an angle of about 10 to 20. The pattern barrel is preferably timed so that the pattern switches 16 have been set for the next shedding sequence shortly before the timing switch 20 closes. Such momentary closure of the timing switch suffices to energize the selected solenoids 14 or 15, and thereby to shoot the piston valve 13 into the selected positions, in which, as already. explained, they remain until the next selection is made. Meanwhile, the slave cylinders respond to the newly-disposed valves,'-with the effect that the selected heald shafts are duly lifted or lowered. After the cam 21 has opened the master timing switchand thereby interrupted all the solenoid circuits for the remainder of the cycle, and manipulation of the pattern switches 16 (whether intentional or not) has no effectvwhatever on the selection already made and initiated, because in such circumstances, the piston valves 13 have already been shot over in accordance with the selection and the solenoids having thus done their work remain disconnected until the timing switch closes again in the next cycle. A manually-operated shaft-levelling control 22 is adapted, when rotated in a clockwise direction as seen in FIG. 1, to lift all the sensing levers 17 which are not already held up by the bowls on the pattern chain 18. The effect, upon rotating the loom crankshaft, is to bring all the heald shafts up to their top positions, which, in the usual manner, facilitates the operations of drawing in a new warp, or examining and when necessary repairing the warp yarns. This shaft-levelling control 22 differs from those hitherto known in that it may be operated at any time in the cycle, even without first stopping the loom, because such intentional manipulation of the pattern switches 16 become effective only upon closure of the master timing switch 20. The purpose of the narrow angle lobe on the cam 21, and the consequent short period the timing switch remains closed in each cycle, is to ensure that in all circumstances the slave cylinders have ample time in which to displace their vibrator levers before the selected gears run into' mesh. If the angle of the cam lobe is unnecessarily extended, it is possible for the levelling control to be operated and take effect late in the cycle, leaving the slave cylinders insufficient time in which to complete their preferably deliberate setting operations before the gears run into mesh. When the said slave cylinders are powered by hydraulic fluid under pressure, that pressure may conveniently be sufficiently high to ensure that the vibrator wheels are rigidly retained in their meshing positions, even underthe heaviest loads, by the arrangement shown in FIG. 1, in which the slave cylinders directly actuate the vibrator levers. Similarly, under light and medium loads, the arrangement shown in FIG. 1 is satisfactory when the slave cylinders are powered by compressed air. In such a case, however, a much lower unit-pressure is usually available, and consequently, althoughthe vibrator levers and their wheels are readily and precisely displaced from one to the other of their operational positions, the retaining force so available may not provide the desirable safety margin to cope with the maximum disengaging force developed by the meshing gears, which coincides with the heald shaft being about midway in its upward movement. The use of larger bore cylinders, which would provide a greater retainingforce with the same unit-air-pressure, is not generally practicable dueto lack of space. In such cases, therefore, each slave cylinder is arranged to displace its coacting vibrator lever through an intermediate linkage, one form of which is shown by FIGS. 2 and 2A wherein 12, 24 and 25 are through bars supported by the frames (not shown). The slave cylinder 11 is flexibly anchored to bar 12, and the piston rod 11a is hinged to arm 26 of a twoarmed lever arranged to swing on bar 24, the other arm 260 being connected bylink 27 to arm 28a of a second lever, arranged to swing on bar 25, with the other arm 28 connected by link 29 to the vibrator lever by pin 6a. As shown in FIG. 2, the piston rod isextended, and holds arm 28 and link 29 in a straight line, thus forming a toggle lock at the outerend of the pistons stroke, corresponding to the vibrator wheel 5 being inrneshing distance with the top cylinder 8. As shown in FIG. 2A the piston rod is retracted, and holds arm 26a and link 27 in a straight line, thus forming a toggle lock at the inner end of the pistons stroke, when link 29 has displaced pin 6a to the position 6b, corresponding to the vibratorwheel 5 being'in meshing distance with the bottom cylinder 9. v . The intermediate linkage shown in FIGS. 2 and 2A thus providesa toggle lock at both ends of the pistons stroke, fully capable of withstandingthe disengaging tendency of the meshing gears under the heaviest loads, and enables the relay mechanism to function satisfactorily in such circumstances when powered by compressed air of moderate unit pressure. A modified and simpler form of intermediate linkage is shown by FIGS. 3 and 3A, wherein 12 and 25 are through bars. The slave cylinder, as before, is flexibly anchored to through bar 12, and the piston rod 11a is hinged to arm 28a of a lever arranged to swing on bar 25, while the other arm 28 of the said lever is connected by link 29 to the vibrator lever 6 by pin 6a. As. shown in FIG..3, the piston rod is retracted and holds arm 28 and link 29 in a straightline, forming a toggle lock which rigidly, retains the vibrator wheel 5 in meshing distance with the top cylinder 8. In FIG. 3A the piston rod is extended, and lever arm 28 has swung about its fulcrum 25 causing link 29 to displace the outer end of the vibrator lever 6 from position 60 to 6b. In this latter case, the vibrator wheel is retained in meshing distance with the bottom cylinder 9, by the slave cylinder, without an intermediate toggle lock, but with the air pressure acting on the full area of the piston. It will be apparent that the selective electrically controlled relay means, hereindescribed, fully complies with the failsafe" principle. To provide against temporary failure of the compressed air supply, a local reserve in the form of a small air receiver is adequate, as therate of compressed air consumption is relatively small. The fluid or airflow to, or preferably from, each slave cylinder is adjustably restricted so as to provide a deliberate movement of the vibrator levers, thereby ensuring quiet operation. Upon completion of the stroke, the forward pressure builds up in the cylinder so as to hold the gears rigidly in mesh, or to hold the toggles fully locked with that same object. While the invention has been described and illustrated in the accompanying drawings in respect to the conventional construction of the Knowles head-motion in which the vibrator levers and connectors are horizontally disposed it is particularly applicable to similar head-motions, or dobbies, in which the vibrator levers and connectors are vertically disposed, and therefore better adapted for actuating horizontal jack levers, in the manner described in our copending application No. 44855/67 filed concurrently herewith. While the pattern switches areherein shown as being actuated by a conventional pattern chain assembled from bowls and tubes, any other form of pattern sensing means capable of the necessary up-down distinction may be employed with corresponding effect. Iclaim: m 1. In a loom head-motion of the kind in which a vibratory lever carrying a vibratory wheel is supported for movement between extreme positions alternately to engage the vibratory wheel with opposed drive wheels to effect rotation of the vibratory wheel first in one direction and then in the other; a reciprocal motor and a mechanical coupling connecting the motor to the vibratory lever, operable in response to signals of opposite sense to effect positive movement of the vibratory lever to one or the other of the extreme positions according to the sense of the signal and hold it at each position until said motor receives a signal of opposite sense and a pattern chain operating in timed relation with the drive wheels operable to produce successive and at predetermined intervals signals of opposite sense. i 2. In a loom head-motion of the kind in which a vibratory lever carrying a vibratory wheel is supported for movement between extreme positions alternately to engage the vibratory wheel with opposed drive wheels to effect rotation of the vibratory wheel first in one direction and then in the other, the provision of means comprising a pivotally mounted cylinder, a piston in the cylinder, a rod rigidly connected at one end to the piston "andpivotally connected at its other end to the vibratory lever, means for supplying fluid pressure to one end of the cylinder, to move the piston therein to the opposite end and to hold it at said opposite end until fluid pressure is supplied to the other end and vented from the one end and a pat tern moving in timed relation to the drive which is operable to successively and at predetermined intervals supply fluid pressure to the opposite ends ofthe cylinder. 3. Apparatus according to claim 2, wherein a two-position valve is operable in one position to supply a fluid pressure to one end of the cylinder and vent it from the other and in the other position to supply it to the other end and vent it from the one end and said pattern is operable to effect shifting of said two-position valve. 5 4. Apparatus according, to claim 3, wherein solenoids are provided to effect movement of the two-position valve and said pattern effects operation of the solenoids. 5. Apparatus according to claim 2, wherein a toggle linkage is interposed between the distal end of the piston rod and the vibratory lever, comprising a fixed pivot, a crank pivotally mountedon the fixed pivot, said crank having two arms, a link pivotally connected at its opposite ends respectively to the vibratory lever and to one arm of the crank, and means pivotally connecting the other arm of the crank to the distal end of the piston rod, said link and said means being so arranged that in one extreme position the pivots connecting the link to the vibratory lever and to the one arm of thecrank lie in a straight line passing through thecenter of the fixed pivot and. inthe other extreme position the means connecting the other arm to the piston rod lies on a line passing through the pivot connecting the one end of the link to the vibratory lever and the axis of the fixed pivot. 6.Apparatus according to claim 2, wherein a toggle linkage is interposed between the piston rod and the vibratory lever, comprising a fixed pivot, a crank pivotally mounted on the fixed pivot, said crank having two arms, a link pivotally connected at its opposite ends respectively to the vibratory lever and to one arm of the crank, a pin pivotally connecting the other arm of the crank to the piston rod, said link and said pin being so arranged that in one extreme position, the pivots connecting the link to the vibratory lever and the one arm of the crank lie on a line passing through the fixed pivot and in the other extreme position the pivot connecting the one end of the link to the vibratory leverand the pin connecting the other arm of the crank to the piston rod lie on a line passing through the fixed pivot. crank, a second link connecting the other arm of the second link to the vibratory lever, said links and cranks being so arranged that in one extreme position the pivots connecting the first link to the first and second cranks lie on a line perpendicular to a, line passing through the pivots connecting the .second link to the vibratory lever and the fixed pivot of the second crank, and in the, other extreme position the pivots connecting the second link to the vibratory lever and to the second crank, lying on a line passing through the axis of the second fixed pivot. 8. Apparatus according to claim 1, wherein there is means operable independently of the pattern chain to prevent transmission of signals to said motor during an interval corresponding to the interval the chain is designed to produce signals. 9. Apparatus according to claim 1, wherein there are pattern switches one for each motor, a sensing lever operable by the pattern to effect operation of each'pattern switch, and means for effecting operation of all of the sensing levers, not previously actuated, independently of the pattern to effect movement of all of the vibratory levers, not previously raised, to a common level with the previously raised vibratory levers.

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