US3478983A

US3478983A - Thread tensioning apparatus

Info

Publication number: US3478983A
Application number: US534729A
Authority: US
Inventors: Pierre Charles Eppendahl; Pierre Maurin
Original assignee: THERMIGUIDES SA
Current assignee: THERMIGUIDES SA
Priority date: 1965-05-14
Filing date: 1966-03-16
Publication date: 1969-11-18
Anticipated expiration: 1986-11-18
Also published as: GB1098215A; FR1444141A

Description

' Nov.,18, l96 9 P. C.EPPEN'DAHL ET AL 3,478,983

THREAD TENSIONING APPARATUS Filed March 16, 1966 2 Shets-Sheet 1 INVENTORS PEEREE C. EPPENDAHL Loan-Jpn, 23M w W541 A'rrorme NOV- 18, 1969 p, c, EPPENDAHL ET AL 3,478,983

THREAD TENSIONING APPARATUS Fild March 16, 1966 v 2 Sheets-Sheet z INVENTORS PIERRE C. EPPENDAHL Q a/M BY MJ, 8M wax ATTORNEY} United States Patent 3,478,983 THREAD TENSIONING APPARATUS Pierre Charles Eppendahl, Lyon, and Pierre Maurin, Caluire, France, assignors to Thermiguides S.A., Lyon, France, a company of France Filed Mar. 16, 1966, Ser. No. 534,729 Claims priority, application France, May 14, 1965,

45,988 Int. 01. B6511 59/12 US. (:1. 242 -1s4 8 Claims ABSTRACT OF THE DISCLOSURE Thread tension control mechanism in which a tension applying device is actuated by tension'sensitive means on which the thread acts in opposition to pressure in a pneumatic system and wherein the pressure in the pneumatic system is maintained by a movable part subject to such pressure and having applied to it a determined but adjustable force to maintain such pressure.

Thisinvention relates to thread tension control mechanism for textile machinery and has for an object to provide a simple form of apparatus which will allow for the effective control of one or more thread tensioning mechanisms from a control station so that, where there are two or more tension control mechanisms controlled from the control station, the tension maintained by the control mechanisms can be simultaneously and similarly controlled and maintained.

(l) A tension-sensitive device, usually in the form of aflever with a thread guiding eyelet at one end and secured at its other end to a pivoted spindle to which is applied a predetermined torque in a direction opposite to that applied to it by the tension in the'thread so that the lever at any moment takes up a position determined jointly by the torque applied to the spindle and the tension of the thread at that moment.

(2) A tensioning device comprising one of the well known types of thread brake, e.g. a pair of discs pressed towards one another by a variable force so as to compress the thread between their flat faces, or a cylindrical body around which the thread passes having associated with it means by which the are over which the. thread is held in contact with it can be varied, or a comb type tensioning device comprising tooth-like prongs giving to a part of the thread a zigzag path and movable so as to vary'the degree to which the prongs intermesh and therefore the form of the zigzag path.

(3) A mechanical connection between the tension-sensitive device and the tensioningdevice whereby the tension-sensitive device, which is disposed so as to be sensitive to the tension maintained in the thread by the tensioning device, operates on the tensioning device to increase the tension if the tension-sensitive device moves in a direction indicating a reduction in tension and to decrease the tension if the tension-sensitive device moves in a direction indicating an increase in tension.

It is important that the tension-sensitive device, which in most cases is a lever as mentioned above, should be as light as possible so that it will react with substantially no delay to any change in the tension in the thread,and

3,478,983 Patented Nov. 18, 1969 not lag appreciably behind its theoretically correct position at any instant due to inertia effects.

In the employment of such thread tensioning apparatus it would be of considerable advantage in types of winding or spinning machine embodying large numbers of spinning twisting or winding units (often as many as 200 such units) all driven together, if the output tension of all the tension control devices could be controlled from a single control station, thus reducing very greatly the time needed to set the whole machine to operate at the required ten- SlOIl.

Where simple tensioning apparatus is used which only applies a fixed amount of frictional drag to the running strand of thread irrespective of the tension at which the thread enters the tensioning device, various systems have been proposed, including electrical, mechanical, pneumatic and hydraulic systems, which vary the force applied to the movable disc of a tensioning device comprising movable and fixed discs between which the thread is gripped. For example, in some cases the tension may be set by applying a predetermined electro-magnetic force to the movable disc of such a device while in other cases the thread passes between the surface of a rigid member and the surface of a flexible metal sheet acted upon by a column of air so as to press the sheet towards the rigid member, and it will be seen that with such devices by varying the electromagnetic force or the pressure of the column of air in a number of similar devices the frictional drag applied by a number of devices to the threads on which they act can be controlled simultaneously.

When, however, it is desired to control a number of tension-control devices each constructed to provide compensation for variations in the tension of the thread entering the device, the problem is more complicated since it is not a case merely of controlling the pressure applied to a length of thread passing between the surfaces of two plates, which pressure, once set, is not varied, but is a question of varying the braking effect applied to the thread in accordance with movement of a tension-sensi tive lever or like tension-sensitive device on which the thread acts in one direction and a predetermined force acts in opposition to the force applied to it by the thread, the braking effect thus being varied automatically in accordance with the tension in the thread entering the control device so as to maintain a constant tension in the thread leaving the control device. What is needed, therefore, is a system in which the predetermined force opposing that of the thread can be applied to any desired number of tension sensitive levers or like tension-sensitive devices simultaneously, and can be precisely varied at any time from a single control position.

For this purpose the use of a stream of air acting on a vane type motor has been proposed, as has the use of a diaphragm on which a column of compressed air derived from a source of compressed air acts in conjunction with gearing arranged to convert the displacement of the centre of the diaphragm into torque applied to the spindle on which the tension-sensitive lever and eye are mounted. These systems are subject to the various disadvantages of systems which demand complicated and often ineffective filtration equipment in order to avoid the accumulation of liquid within the column of air which reduces sensitivity or even renders the apparatus inoperative. Moreover in such systems employing a column of air under pressure, while means 'are provided which automatically admit additional air to restore the said pres sure following a drop in pressure there are no means permitting escape of air to prevent a rise in pressure above the said pressure. The systems in question do not, therefore, take into account the effect of simultaneous similar movements of the tension-sensitive levers of a number of the devices which will reduce the total volume of air in the system and thus cause a rise in the pressure in the column and hence mal-operation of neighbouring devices. Pressures substantially above the set pressure may therefore be created and exist in the system for long periods. Such systems also require the use of a compressed air supply involving the cost of installing and maintaining such supply, even disregarding the power needed for this purpose.

It is an object of the present invention to provide a form of thread tension control apparatus which will not be subject to the disadvantages indicated above as present in existing systems, which will be simple and will, when required, enable a large number of tension control devices to be simultaneously and similarly controlled from a single control point and will not involve the expenditure of power.

Thread tension control mechanism according to the present invention comprises a movable tension-sensitive member arranged to be acted upon by the thread so that increases in the tension of the latter cause movement of such tension-sensitive member against the action of a controlling force and vice versa, and a tension applying device actuated by such movement of the tension-sensitive member in a manner tending to maintain a constant tension in the thread for any given value of the controlling force, 'wherein the means for applying the controlling force comprises a pneumatic system the pressure in which is at any moment the same throughout the system and can be adjusted by an adjustable pressure controlling device which includes at least one movable part which is subject to the pressure in the system and is arranged to have a determined but adjustable force applied to it to determine the pressure maintained in the system.

Since the movable part therefor has a constant force applied to it, it maintains automatically a constant pressure in the system and therefore a constant precise force acting on the tension-sensitive levers or other tension-sensitive devices, any movement of one or more of the tension-sensitive levers or like-tension-sensitive devices in no way affecting the pressure in the system since any change in the volume of air in the system will merely result in a movement of the movable wall without a change in the force applied to it. It will be understood that there may be momentary increases or reductions in the pressure in the system which causes movements of the movable wall but such changes will be both momentary and slight, assuming, as will be the case, that the movable wall has small or negligible inertia.

Conveniently the pressure controlling device is in the form of a chamber one wall at least of which is movable to vary the capacity of the chamber, and means for applying to that wall the determined but adjustable force whereby any one of a number of corresponding determined pressures within a predetermined pressure range can be maintained within the whole system, independently of limited changes which may occur in the volumetric capacity of the system as a whole. For example, the force applied to the movable wall may be applied by means of a weight or weights so that, by selection of the appropriate weight or weights any desired pressure within the predetermined pressure range can be maintained throughout the system.

In any case it will be seen that the fluid in the pneumatic system acts merely as a transmission element between the means for applying the required force to the tension-sensitive members and the movable wall to which a constant but adjustable force is applied by a weight or other means.

The chamber may be in the form of a cylinder and piston assembly of which the piston constitutes the movable wall or for example in the form of a bellows device one end of which constitutes the movable wall. In any case the force applied to the movable wall, whether by weights or otherwise, may be applied in a direction such as either to maintain a pressure in the system above atmospheric pressure or to maintain a pressure in the system below atmospheric pressure, preferably the latter.

Preferably the tension-sensitive device will be in the form of an arm which is connected at one end to a spindle mounted to rock in bearings and carries at its other end an eye through which the thread passes in its travel between two fixed guides disposed so that the tension in the thread tends to rock the arm and its spindle about its pivotal axis in one direction, while the spindle is urged in the other direction by a pneumatic device, e.g. in the form of a diaphragm, which is subject to the air pressure in the pneumatic system and thus applies to the spindle a force dependent upon the pressure in the pneumatic system. The movement of the arm then serving to vary the braking force applied to the thread by a braking device in advance of the tension-sensitive device. In one such arrangement employing a pneumatic diaphragm subject to sub-atmospheric pressure in the system the centre of the diaphragm may be connected to one end of a short length of high tensile synthetic yarn the other end portion of which is wound around the spindle, or a pulley on the spindle, two or three times so that when a subatmospheric pressure is applied to the face of the diaphragm remote from the high tensile synthetic yarn, the diaphragm exerts a tension on the length of yarn tending to rotate the spindle. Such a device will thus be sensitive with very little inertia and be substantially frictionfree as compared with arrangements embodying, for example, rack and pinion gearing. Moreover the use of subatmospheric pressure in the pneumatic system reduces the specific mass of air present in the system, thus reducing inertia effects, the sensitivity of the system being in fact inversely proportional to the inertia of the various parts and masses which have to move to control the tension.

In addition the employment of sub-atmospheric pressure avoids any need for scavenging or filtering units or bleed units for removing moisture. In machines embodying a tension control mechanism according to the invention employing a number of tension control devices the column of air the pressure of which determines the tension to be maintained can be led to the various units by way of the hollow tube which in many cases runs the length of the machine and has the tension regulating devices supported upon it.

One form of apparatus according to the invention and a modification thereof are shown in the accompanying drawings, in which:

FIGURE 1 is a diagrammatic view of a complete control system as installed,

FIGURE 2 is a front elevation of one of the tension controlling units,

FIGURE 3 is a cross sectional side elevation on the line 3-3 of FIGURE 2,

FIGURE 4 is a cross section on the line 4--4 of FIG- URE 3,

FIGURE 5 is a front elevation on a somewhat larger scale than FIGURES 2 and 3 of the frictional device by which the tension is controlled,

FIGURE 6 is a plan view of the device shown in FIGURE 5,

FIGURE 7 is a sectional side elevation of a modification of the arrangement shown in FIGURE 1, and

FIGURE 8 is a side elevation showing a modification of the arrangement shown in FIGURE 4.

In the arrangement shown in FIGURE 1 the control system comprises a unit A for providing a controlled subatmospheric pressure in a pneumatic system comprising a passage B representing a pneumatic column, which passage is connected by branch passages C to the individual tension regulating units p p pg, 17 17, which may be any convenient number as indicated, and by a further passage to a sub-atmospheric pressure reservoir D. As shown in FIGURES 2, 3 and 4 each of the tension regulating units 17 p etc. comprises two half shells 1a and 1b between flanges on which is gripped in a fluid tight manner the edge of a diaphragm 2, constituting a pressure Sensitive member, which thus provides an air tight partition between a chamber subject to sub-atmospheric pressure due to its connection with the passage C and a chamber which is subject to atmospheric pressure. The half shell 1a supports a casting 4 constituting a supporting member in which is pivotally mounted, preferably upon ball bearings 5, a spindle 6 which has rigidly attached to it a pulley 7 and one end of a lever 8, constituting the movable tension sensitive means, the lever being provided at its other end with a thread guide 9. A small friction pad 10 may be provided around the spindle 6, if needed, to prevent the thread cutting into the spindle 6.

Some small amount of frictional damping may be applied to the spindle 6 in some cases.

The diaphragm 2 is connected at its centre by a connecting piece 11 to one end of a thin and flexible length of yarn or cable 12 constituting a tension member the opposite end portion of which is wound round the circumferential surface of a pulley 7 on the spindle 6 and is anchored to a predetermined point on the rim of the pulley.

Also carried by the supporting piece 4 is a plate 13 provided with two fixed thread guides, as indicated generally at 14 and 15, which serve to guide the thread respectively on its way to and from the tension regulating unit. In some cases the guide 15 may be unnecessary, that is to say where the disposition of the parts is appropriate.

Also rigidly secured to the plate 13 is the stationary part 16 of a tension applying device, this part being of arcuate form and U-shape cross section as shown in FIGURES 2 and 3 and having in its upturned lateral edges notches 17 which serve to guide the thread in its passage across the part 16, while the other part of the thread tensioning device comprises an arcuate shaped rib 18 secured to a plate 8a rigid with the arm 8 and lying and moving between the upturned sides of the part 16, the rib 18 varying in depth throughout its length so that the degree of deflection imposed by its on the part of the thread extending across the part 16 between the notches 17 depends upon the angular position of the arm 8.

The sub-atmospheric pressure which exists in column B, C causes the diaphragm 2 to be forced by atmospheric pressure to the right in FIGURE 4 and this in turn applies tension to the thread 12 which imparts to the spindle 6 and lever 8 a torque tending to deflect the lever 8 in the direction shown by the arrow x in FIGURE 2 thus causing the guide 9 to bear against the part of the strand of thread 19 between the

frictional device

16, 18 and the guide 15 as shown. If, therefore, the tension in the thread approaching the guide 14 should decrease so that the tension in the part of the thread between the

device

16, 18 and the guide 15 similarly decreases the lever 8 will move to the left in FIGURE 2 so that the rib 18 moves arcuately within the U-shaped member 16 to depress the part of the thread extending across the U- shaped member 16 more deeply into the space between the notches 17, thus increasing the tension of the thread by the application of increased friction thereto to a degree depending upon the tension of the thread approaching the guide 14. Thus each tension controlled device acts in a manner tending to maintain substantially constant tension in the part of the thread leaving its guide 15.

The adjustable pressure controlling device shown in FIGURE 1 for applying and maintaining the desired subatmospheric pressure in the column B, C comprises a cylinder 21 the upper end of which is in direct communication with the passages B, C, the cylinder 21 containing a movable part constituted by a piston 22 provided with a piston rod 23 extending below the lower end of the cylinder 21 and provided at its lower end with a supporting platform 24 on which weights 25 can be placed. A

valve'26 is provided which when opened allows the piston 22 to be raised to the top of its cylinder 21 while it can also allow the system to be momentarily connected to a reduced pressure source during operation if desired. In any event the valve 25 is closed during normal operation of the system with the piston 22 in an appropriate position near the top of the cylinder 21 and a suitable load applied by the weights 25 to the piston.

It will thus be seen that by the selection of suitable weights for application to the platform 24 any desired sub-atmospheric pressure within an appropriate range can be applied to and maintained in the system comprising the passages B, C and that this selected subatmospheric pressure will be maintained independently of movements of the diaphragms 2 and of changes in temperature.

If desired, instead of the piston and cylinder arrangement shown at 21, 22, 23 in FIGURE 1, a bellows arrangement as shown in FIGURE 7 may be employed comprising a bellows 27 the interior of which is in continuous communication with the passage C and has associated with it a valve 26 corresponding to the valve 26 in FIGURE 1, the lower end of the bellows having secured to it the upper end of a rod 23' the lower end of which carries a supporting platform 24 on which weights 25 can be placed so that the device as a whole maintains a sub-atmospheric pressure in the passages B, C in a similar manner to the

device

21, 22, 23, 24, 25 in FIGURE 1. In the construction shown in FIGURE 7 the bellows has incorporated in it a hydraulic damping device of the dashpot type indicated at 28 to prevent vertical vibratory movements of the lower end of the bellows.

In the modification shown in FIGURE 8, which may be regarded as incorporated in the part of the apparatus shown in FIGURE 4, instead of the corresponding parts shown in FIGURE 4, the spindle 6 has rigidly mounted on it two

adjacent pulleys

29 and 30 of different effective diameter while the diaphragm 2 has a pulley 31 mounted in bearings 32 for example ball bearings, in a bracket attached to the centre of the diaphragm, the tension thread 12 passing around the pulley 31 and being secured at its ends respectively to the circumferential parts of the

pulleys

29 and 30 at diametrically opposite points. This arrangement provides differential apparatus by which measurable differences in the sub-atmospheric pressure acting on the diaphragm 2 will produce very small differences in torque on the spindle 6 and lever 5.

It is to be understood that the invention also includes within its scope systems similar to those described as employing sub-atmospheric pressures but in which, instead of a piston and cylinder device or a bellows and weights producing a sub-atmospheric pressure, a piston and cylinder or bellows assembly and weights are arranged to provide a super-atmospheric pressure in the pneumatic system, it being understood that in this case the mechanism connecting the diaphragms or the like to the tension control members would be correspondingly modified so that the torque applied to the spindle 6 or its equivalent due to the super-atmospheric pressure would be in the correct direction.

What we claim as our invention and desire to secure by Letters Patent is:

1. Thread tension control mechanism comprising:

movable tension-sensitive means arranged to be acted upon by a thread so that increases in the tension of the latter cause movement of said at least one tension-sensitive means against the action of a controlling force and vice versa;

a tension-applying device actuated by such movement of said at least one tension-sensitive means in a manner tending to maintain a constant tension in the thread for any given value of the controlling force;

means for applying the controlling force comprising a pneumatic system containing fluid the pressure of which is at any moment the same throughout the system, a pressure sensitive member subject to the pressure of the fluid in the pneumatic system, and an adjustable pressure-controlling device for adjusting the pressure in the system, said adjustable pressure controlling device including at least one movable part which is subject to the pressure in the system; and

means for applying a determined but adjustable force to said movable part to maintain a corresponding determined but adjustable pressure in the system.

2. Thread tension control mechanism as claimed in claim 1 in which the pressure controlling device is in the form of a chamber forming part of the pneumatic system and one wall at least of which is movable to vary the capacity of the chamber and constitutes the movable part on which the means for applying the adjustable force acts.

3. Thread tension control mechanism as claimed in claim 2 in which said tension-sensitive means comprises a pivoted spindle having a circumferential surface thereon, an arm one end of which is rigidly connected to said spindle, a thread guide at the other end of said arm, said pressured sensitive member comprising a diaphragm, and a tension thread having one end portion wound at least partially around the said circumferential surface on the spindle and connected at its other end to said diaphragm.

4. Thread tension control mechanism as claimed in claim 3 in which the means for applying said adjustable force to said movable wall comprises a support attached to said movable wall and arranged to have weights of various mass applied to it.

5. Thread tension control mechanism as claimed in claim 2 in which the means for applying said adjustable force to movable wall comprises a support attached to said movable wall and arranged to have weights of various mass applied to it, and wherein the means for applying the adjustable force to the movable wall applies such forces in a direction to increase the volumetric capacity of the chamber so as to provide therein and in the pneumatic system a sub-atmospheric pressure.

6. Thread tension control mechanism as claimed in claim 1 in which said tension-sensitive means comprises a pivoted spindle, an arm one end of which is rigidly connected to said spindle, having a circumferential surface thereon a thread guide at the other end of said arm, said pressure sensitive member comprising a diaphragm, and a tension thread having one end portion wound at least partially around the said circumferential surface on said spindle and connected at its other end to said diaphragm. 7. Thread tension control mechanism as claimed in claim 1 including a plurality of tension-sensitive means and associated tension-applying devices each actuated by movement of its associated tension-sensitive means, wherein the pneumatic system comprises a tube serving not only to' transmit the adjustable pneumatic pressure to each pressure sensitive means but also as a support for each tension-sensitive means and their associated tensionapplying devices.

8. Thread tension control mechanism as claimed in claim 1 in which said at least one movable tension-sensitive means comprises a pivoted spindle, an arm one end of which is rigidly connected to the spindle, a thread guide at the other end of said arm, in which said pressure sensitive member comprising a diaphragm, two pulleys of different diameter secured to said spindle, a third pulley rotatably connected to said diaphragm and a flexible tension thread the ends of which are connected respectively to circumferential points on said two pulleys while an intermediate part thereof passes round said third pulley.

References Cited UNITED STATES PATENTS 2,610,813 9/1952 Campbell 242- 2,888,216 5/1959 Simons, et al. 242149 X 3,223,351 12/1965 Lemarchand 242154 STANLEY N. GILREATH, Primary Examiner