ROTARY DOBBY

Abstract

 A rotary dobby comprises a common driving shaft (1) kinematically associated with a main shaft (3) of a loom (4) to transmit rotation at a uniform angular speed for which purpose the common driving shaft (1) is provided with cams (25, 26) for imparting a rocking motion to swivel locking means (10, 11) of crown gears (9) and pinion carriers (8) of planetary engaging clutches (6) relatively to the center line of the common driving shaft (1), the swivel locking means (10, 11) being associated with a programmable device (12) through the medium of link gears (27, 28).

Description

[0001] The present invention relates to the art of textile machine building and is particularly concerned with the construction of a loom dobby.

Background of the Invention

[0002] The most favorable dynamics of movement of healds and respectively the most high-speed operating modes of a loom shedding motion are attained when uniformly rotating cranks are used as drives of heald frames. However, in this case, the assortment of produced fabrics is limited by a plain weave.

[0003] Known in the prior art is a drive for the healds of a loom (SU, A3, 398049, 1974), the cranks of which are rotating at an angular speed changing in a pulsing cycle in which for converting a uniform rotational speed of a loom main shaft into a variable speed a differential drive speed modulator is built in the input of a dobby (CH, A5, 531073, 1974). As a result, the rotational speed of the cranks changes within the limits from an instantaneous stoppage and to an excess of the speed by 1.5 times. The instantaneous stoppage of the cranks causes an increase in the dwelling period of the healds in the open shed (up to 120 deg of the loom main shaft angle) and respectively causes a decrease in movement of the healds and leads to their inertial overloading. In practice, the speed of known dobbies provided with a speed modulator is limited by a number of weft threads laid in a minute and amounts to 500 min⁻¹. In this connection the pneumatic looms operating at a rotational speed of the main shaft of up to 1000 min⁻¹ are provided with hook-type dobbies which need no speed modulation at the input.

[0004] Other disadvantages of the known rotary dobbies reside in high speeds of movement of the shed on the loom resulting in an intensive loom wear of warp threads and a deep modulation of the speed turns out to be a kinematic exciter of vibrations and noise on the loom.

[0005] Also known in the prior art is a rotary dobby comprising a common driving shaft associated with a loom main shaft through a kinematic transmission and provided with planetary engaging clutches the number of which corresponds to the number of heald frames, and which cooperate with a programmable device and cranks of lever motions of the heald frames by means of sun gears, pinion carriers, crown gears and locking means installed on pivots (SU, AF, 1647049, 1991).

[0006] Known in the prior art is a loom rotary dobby provided with a control mechanism comprising a program carrier (SU, A1, 1602893, 1990).

[0007] Also known in the prior art is a loom rotary dobby provided with a differential common drive for modulation of the speed at the dobby input (SU, A1, 787500, 1980).

[0008] Known in the prior art is a device for controlling the movement of a heald frame (US, A, 3568724, 1971) by means of a lever the upper portion of which controls the movement of the heald frames by way of lifting, lowering and keeping them at rest in compliance with the work cycle.

[0009] The main disadvantage of the known rotary dobbies resides in the use of a deep modulation of the speed at the input which limits the operating speed of the dobby on the loom to 500 cycles of laying weft threads per minute.

[0010] For comparison, it should by noted that the kinematic and dynamic characteristics of such dobbies give way to the respective characteristics of a shedding motion with the heald frames driven by uniformly rotating cranks: with respect to design maximum operating speeds of the heald frames - by 1.5 times, with respect to accelerations - by 1.7 times and with respect to loads on the crank - by 2.4 times. As to the dynamic characteristics, they will be even much higher as it has been proved by experiments.

Summary of the Invention

[0011] The basis of the present invention is the task of stepping up the operating speed of a rotary dobby on a loom by improving the kinematic and dynamic characteristics of the movement of heald frames.

[0012] The above task is solved by the fact that, in a rotary dobby comprising a common driving shaft kinematically associated with a loom main shaft, a planetary engaging clutch for each heald frame cooperating by means of a sun gear, a pinion carrier, a crown gear and swivel locking means installed on pivots with a programmable device and with a crank of a lever motion of the heald frame, according to the invention, the common driving shaft of the rotary dobby is provided with cams operating by means of rollers, correspondingly associated via rockers and links with rockers freely installed on the common driving shaft, to which are attached the pivots with rotating locking means cooperating with the programmable device through the medium of a link gear.

[0013] Another alternative embodiment of the present invention may also be in the form of a dobby wherein the rocking axis of the rockers may be displaced relatively to the centre line of the driving shaft. In this case the link gear may be in another form.

Brief Description of the Drawings

[0014] The invention will now be described with reference to the construction of a rotary dobby of a loom taken in conjunction with the accompanying drawings, wherein:

Fig.1 illustrates a kinematic diagram of a proposed rotary dobby;

Fig.2 illustrates a cross-sectional view of a planetary engaging clutch taken along the line A-A of Fig.1;

Fig.3 illustrates a cam mechanism of pivots of swivel locking means of planetary engaging clutches.

Description of the Preferred Embodiment

[0015] A rotary dobby comprises a common driving shaft 1 associated by a kinematic transmission 2 with a main shaft 3 of a loom 4. The common driving shaft 1 is provided with planetary engaging clutches 6 the number of which corresponds to the number of heald frames 5 of the loom 4, and each of which cooperates with a programmable device 12 and with a crank 13 of a lever motion of the heald frame 5 by means of a sun gear 7 secured on the common driving shaft 1, a pinion carrier 8, a crown gear 9 and locking means 10 and 11 intended respectively for locking the pinion carrier 8 and the crown gear 9. The locking means 10, 11 are hingedly installed on pivots 15, 16. The latter are secured on rockers 17 and 18 (Fig.3) freely mounted on the common driving shaft 1 and associated through the medium of connecting rods 19 and 20 with rocking bars 21 and 22 whose rollers 23, 24 are intended for locking cams 25 and 26 secured on the common driving shaft 1. Fig.3 illustrates the position of the cam mechanism at a moment when the heald frame 5 is dwelling in the open shed and the planetary engaging clutches 6 are being changed over.

[0016] Through the medium of links 27 and 28 the locking means 10 and 11 are connected with rocking bars 29 and 30 of the programmable device 12, associated with each other by means of a connecting rod 31 and preloaded by springs 32 and 33 disposed on rods 34 and 35. The rod 35 is hingedly associated with a signaling means 36 which cooperates with a program carrier (not shown in the drawing) of the heald frame and also cooperates by its projection 37 with a knife blade 38 of a rocking bar 39 connected to the lever motion 14 and kept in constant contact with a knife 40.

[0017] The rotary dobby operates in the following manner.

[0018] The position of the signaling means 36 preset by the signal received from the program carrier in the preceding work cycle of the loom is reproduced by the heald frame in the subsequent cycle.

[0019] Fig.1 illustrates the heald frame 5 in the downward position and the signaling means 36 in a position corresponding to the downward position of the heald frame 5 in a subsequent work cycle of the loom.

[0020] When the knife 40 moves forward the projection 37 of the signaling means 36 gets under the knife blade 38 of the rocking bar 39. As a result, the rod 35 moves to the left and the spring 32 holds the rocking bars 29, 30 in the starting position, the pinion carrier 8 remains locked by the locking means 10 and the crown gear 9 remains not locked by the locking means 11. The crank 13 associated by a toothed ring thereof with the pinion carrier 8 holds the heald frame 5 in the downward position during the entire work cycle of the loom taking place after the work cycle being under consideration.

[0021] When the position of the signaling means 36 is changed to the opposite (shown in the drawing by a dash-and-dot line) the projection 37 does not get under the knife edge 38, the rod 35 remains in the position shown in Fig.1 and on approach of a successive tooth space of the crown gear 9 the spring 33 overcoming the resistance of the spring 32 locks the crown gear 9 through the medium of the locking means 11. As a result, the rocking bars 29, 30 will be turned clockwise and the locking means 10 will release the pinion carrier 8 which will transmit rotation of the main shaft 3 of the loom 4 to the crank 13, and the heald frame 5 will be moved from the downward position into the upward position in the subsequent work cycle through the medium of the lever motion 14.

[0022] Cooperation of the planetary engaging clutch 6 with the locking means 10 and 11 is effected in the process of the change-over in the following manner.

[0023] An angular speed ω_i of the sun gear 7 is equal in magnitude and coincident in direction with an angular speed ω_m.s of the main shaft 3 of the loom 4 (Fig.1).

[0024] When the crown gear 9 is stationary (ω_c.g. = 0) an angular speed ω_p.c. of the pinion carrier 8 coincides in direction with the angular speed ω_i of the sun gear 7 and is equal to:

[0025] When the pinion carrier 8 is stationary (ω_p.c. = 0) the value of the angular speed ω_c.g of the crown gear 9 is determined by a simple transmission comprising the gears 7 and 9:


and in direction the ω_c.g. is opposite to the ω_i.

[0026] In the process of the change-over of the planetary engaging clutch 6 the rocker 17 turns in the direction of rotation of the pinion carrier 8, and the rocker 18 turns in the direction of rotation of the crown gear 9.

[0027] Speeds of the rockers are taken to be equal to:

[0028] Through the medium of the locking means 10, 11 installed on the pivots 15, 16 the rockers 17 and 18 transmit their speeds of turning to the locked pinion carriers 8 and the crown gears 9 of the planetary engaging clutches. The pinion carriers 8 or the crown gears 9 locked by the locking means 10, 11 impart the additional speeds through the planetary mechanisms to the crown gears 9 or the pinion carriers 8 which are not locked by the locking means 10, 11. The additional speeds of the pinion carrier 8 and the crown gear 9 (when the sun gear 7 is stationary by convention) of the planetary engaging clutch 6 are associated by the relation:
   with

[0029] These speeds coincide in direction.

[0030] Absolute speeds of the free (not locked by the locking means) pinion carrier 8 or crown gear 9 are formed by algebraic addition of components of speeds from two sources of motion: firstly, from the sun gear 7 and secondly, from the rocker 17 of 18 engaged by its locking means 10 or 11 with the planetary engaging clutch 6.

[0031] Hence, the absolute angular speed of the pinion carrier 8 will be:

or

[0032] Rotation of the pinion carrier 8 at a speed of


is accompanied in the process of the change-over of the planetary engaging clutch 6 by turning of the rocker 17 at the same speed

[0033] Condition for shockless locking of crown gear 9 is obtained in the way similar to that described hereinbefore:

   or

[0034] Movement of the rockers 17, 18 is smoothly retarded after the planetary engaging clutch is completely locked by the respective locking means which provides for a smooth acceleration of the unlocked crown wheel 9 or the pinion carrier 8 up to a constant speed maintained in the mainphase interval of the heald movement.

[0035] Low absolute angular speeds of the lockable pinion carrier 8 (

) and crown gear 9 (

) define small angles of rocking of the rockers 17, 18, provide the possibility for changing over the planetary engaging clutches 6 in the zone of extreme positions of the crank 13 and simplify the geometry of profiles of the cams 25, 26. In the zone of active movement of the healds 5 the crank 13 rotates at a constant speed equal to a sum of the half of the angular speed of the common driving shaft 1 and a small addition of the constant speed of the smooth return rocking of the rockers 17, 18 into the starting position.

[0036] By way of changing the size of arms of the rocking bars 21 and 22 (Fig.3), the relative speeds of sliding of the locking means 10, 11 and the planetary engaging clutches 6 differing from zero values are easily preset.

[0037] Let us take as an embodiment the turns of the rockers 17 and 18 in the form of a standard law:


   upon differentiation of which the angular speed ω_i of turns of the rocker is expressed by the formula:


where:
   T is the phase angle of turn of the common driving shaft 1 when the rocker turns from one extreme position into the opposite one.
   Θ_i is the current value of angles of turn of the common driving shaft 1.

[0038] If

[0039] The speeds of the rocker 17 and the crown gear 9 are equalized, if

[0040] The required angle of rocking of the rockers is equal to:


- for the rocker 18 of the locking means 11 of the crown gears 9,


- for the rocker 17 of the locking means 10 of the pinion carrier 8.

[0041] Let us take a phase angle T⁽¹⁾ of acceleration of the rocker 18 to the speed of rotation of the crown gear 9 to be equal to 30 deg. The angle of rocking of the rocker in the period T⁽¹⁾ of its acceleration amounts to:

[0042] Further, let us take a phase angle T⁽²⁾ through which the locking means 10 accompanies the crown gear 9 to be also equal to 30 deg. In this case the angle of rocking of the rocker on a section of movement at a constant speed: ω_m.s /6 - for the locking means 11 of the crown gears 9 and at a speed of ω_m.s /8 - for the pinion carriers 8 is equal to:


- for the rocker 18 of the locking means 11 of the crown gears 9,


- for the rocker 17 of the locking means 10 of the pinion carriers 8.

[0043] The planetary engaging clutch 6 will be locked in the phase

of turning of the common driving shaft 1 and turning of the rockers 17, 18 through an angle

   respectively for the locking means 11 of the crown gears 9:

and for the locking means 10 of the pinion carriers 8:

[0044] Let us take the overtravel of the rockers 17, 18 in a phase T⁽³⁾ to be equal to 30 deg which corresponds to the angles of turn of the rockers 17, 18 in the process of their acceleration. At this section of the cycle the locking means 10, 11 are blocked by external surfaces of the planetary engaging clutches 6.

[0045] The complete phase period T of the turn of the rockers 17, 18 is equal to 90 deg and complete angles of rocking S are respectively equal to: 10 deg - for the rocker 18 of the locking means 11 of the crown gears 9 and 7.55 deg - for the rocker 17 of the locking means 10 of the pinion carriers 8. The change-over and blocking of the locking means 10 of the pinion carrier 8 is accomplished at an angle of turn of the crank 13 equal to the doubled angle of turn of the rocker of the locking means of the pinion carriers 8 (15.1 deg) - within the limits of the heald frame dwelling in the open shed.

[0046] An advantage of the proposed invention resides in that in the period of the shed main movement the heald frame is actuated by means of the crank rotating at a uniform speed and for obtaining a shockless change-over effected in a short period of the open shed dwelling the pivots of the locking means are accompanying the rotary motion of the pinion carriers and crown gears of the planetary engaging clutch. The shockless change-over of the pinion carriers and the crown gears of the planetary engaging clutches by the locking means is insured by the combined action of four factors: (1) accompaniment of the rotating lockable tooth spaces of the crown gear or the pinion carrier by the free locking means, (2) reduction of the speed of the lockable tooth spaces at the expense of turning the lockable tooth spaces by the locking means, (3) reduction of the angular speed of the common driving shaft effected on the pinion carriers and the crown gears, (4) installation of the cams for driving the pivots of the locking means on the high-speed common driving shaft. The use of technical capabilities laid down in the four factors described hereinbefore makes it possible to dispense with a speed modulator at the input of the dobby and thus to substantially improve the mechanical characteristics thereof by way of increasing the speed characteristic of the dobby by 2 times, decreasing the kinematic inertia loads by 1.7 times and by reducing the level of noise and vibrations of the loom.

Industrial Applicability

[0047] A rotary dobby with a planetary principle of the change-over and without a speed modulator at the input is designed for use on all main types of shuttleless looms for production of fabrics of wide assortment from all kinds of fibres.

Claims

1. A rotary dobby comprising a common driving shaft (1), kinematically associated (2) with the main shaft (3) of a loom (4), a planetary engaging clutch (6) for each heald frame (5), cooperating through the medium of a sun gear (7), a pinion carrier (8), a crown gear (9) and swivel locking means (10,11) installed on pivots (15,16), with a programmable device (12) and with a crank (13) of a lever motion (14) of the heald frame (5), characterized in that the common driving shaft (1) of the dobby is provided with cams (25,26) cooperating by means of rollers (23,24) correspondingly associated via rockers (21,22) and links (19,20) with rockers (17,18) freely installed on the common driving shaft (1), to which are attached the pivots (15,16) with the swivel locking means (10,11) cooperating with the programmable device (12) through the medium of link gears (27,28).

Drawing