US3797279A - Thread-feeding, tension-regulating device for straight knitting machines - Google Patents

Abstract

Thread-feeding, tension-regulating device for straight knitting machines, comprising a tensioning arm having a threading member at its free end, supplementing those of the associated machine, with resilient means tending to lift the free end of the supplemental arm, and a device for multiplying the displacements, interposed between a movable application point of the resilient means and that of the pressure exerted on the body of the supplemental arm. The latter performs a substantial angular displacement despite of a very small displacement of the movable application point, the pressure of the resilient means thus remaining virtually uniform along the path of the angular displacement. The inventive device can take various constructional forms.

Description

United States Patent Kline et al.

THREAD-FEEDING,

TENSION-REGULATING DEVICE FOR STRAIGHT KNITTING MACHINES [76] Inventors: Luis Kline, Estados Unidos 1666;

Fernando J. Silberman, Chacabuco 145, both of Buenos Aires, Argentina [22] Filed: May 25, 1972 [21] Appl. No.: 256,691

[30] Foreign Application Priority Data May 26, 1971 Argentina 235806 [52] U.S.- C1. 66/126 R, 66/146 [51] Int. CL. D04b 15/52, D04b 15/56, D04b 15/64 [58] Field of Search 66/70, 76, 126, 146

[56] References Cited UNITED STATES PATENTS 94,135 8/1869 Roper 66/76 109.793 12/1870 Allen. 66/126 R X Piltz 66/146 Schurich 66/146 X Primary ExaminerRobert R. Mackey Attorney, Agent, or FirmTab T. Thein [57] ABSTRACT Thread-feeding, tension-regulating device for straight knitting machines, comprising a tensioning arm having a threading member at its free end, supplementing those of the associated machine, with resilient means tending to lift the free end of the supplemental arm, and a device for multiplying the displacements, interposed between a movable application point of the resilient means and that of the pressure exerted on the body of the supplemental arm. The latter performs a substantial angular displacement despite of a very small displacement of the movable application point, the pressure of the resilient means thus remaining virtually uniform along the path of the angular displace ment. The inventive device can take various constructional forms.

11 Claims, 1 1 Drawing Figures Pmmmmlsmm 3.797.279

' sum 1 or 3 FIG.

THREAD-FEEDING, TENSION-REGULATING DEVICE FOR STRAIGHT KNITTING MACHINES The invention relates to a thread-feeding, tensionregulating device that may be applied to generally all knitting machines, for taking up unnecessary slack in the dispensed thread and maintaining the required uniform thread tension.

Tensioning devices which have been used so far with industrial as well as home-use knitting machines-are only able to take up a very small excess of thread in comparison to the distance traveled by the carriage, as related to the edge of the produced fabric. The excess of thread taken up by the known devices amounts to but a few centimeters; therefore, a special device becomes necessary for industrial power-driven knitting machines, designed to limit the travel either of the carriage or, if applicable, of the thread holders to a few centimeters in excess of the edge of the fabric.

Each time the width of the fabric is to be substantially increased or reduced, the special device has to be ad-.

justed to the new width. The desired result is thus attained, that is: the carriage or the thread holders travel but a few centimeters in excess of the fabric edge; however the fabric may not be located on the knitting machine at ones free choice since it has been preset by the special device which limits said travel, and such location depends moreover on whether knitting is performed with a single-thread or multi-thread machine and with an appropriate type of thread holder.

As for home-use knitting machines, which gained world-wide popularity in recent years, the carriages are manually driven. Stoppage of the carriage in such a machine, after having traveled beyond the fabric edge, will present no trouble under such circumstances. However if owing to whatever reason the carriage travels in excess of the due distance, the person handling the machine is forced to pick up the excess thread manually in order to enable the tensioning device to operate properly.

This happens because the thread-feeding tension represents a critical point with regard to the operation of industrial as well as home-type knitting machines. Excess thread tension will result in bad performance of the machines: the carriage travels will drag, the needles will bend, and the threads will tear. On the other hand, lack of thread-feeding tension will result in a slack fabric, stitches will slip from the needles, and the pattern will become faulty; the yarn or thread will get entangled around and between the needles, thus forcing the attendant to interrupt the knitting.

Therefore the tensioning appliance must make sure that thread feeding occurs at the very moment the machine operation requires the thread to be fed; however the carriage should not cause an excess output of knit ting thread during its return travel with regard to the fabric edge, namely in excess of the output which the tensioning device is able to pick up, in order to prevent tension reduction and thread slackening during the subsequent carriage travel.

Shortly after the modern home-use, hand-actuated knitting machines were popularized, interest arose in achieving a higher mechanical performance, such as by means of a power drive. Such interest resulted initially in greater comfort for the housewife who-knits fabrics for her own family use, since the manual operation of the machine carriage becomes very tiresome after a few hours for average persons, and is sometimes impossible for the aged or disabled.

Such interest however was still increased when, shortly after said machines came into use, a small craftsman-like industry was set up. By virtue of their low cost, easy handling, simple maintenance and versatility, small workshops with a varying number of machines were setup shortly after the appearance of these home-use knitting machines, which were until then hand-actuated by the craftsmen, sometimes for more than one shift. I

Initial attempts to power drive these home-use knitting machines were quite unsuccessful. The problem was easily solved when it was a matter of driving a home knitting machine designed to knit a piece of fabric of a fixed and uniform width. This could be achieved by means of an endless chain causing the carriage to perform its travel, which drive is well known for industrial machines. In very few cases was it however a matter of knitting pieces of fabric of fixed and uniform width when working with the home-use machines, even when using them in small craftsman-like workshops.

On the other hand, not one of the several industrial device types, designed to adjust the travel of the loom carriage or of the thread holders to the width of the fabric,. is adaptable to home-use knitting machines and their field of application. Actually such devices are not only complicated and expensive but their handling and maintenance require skilled craft which is of course neither available for home use nor, generally, for the mentioned small industrial workshops.

'So far it proved impossible to achieve a practical way in order to adapt the traditional tensioning devices to power-driven home-use knitting machines, either by increasing the size of such appliances or by any other means. This is due to the substantial tension difference resulting from the various operating positions of such tensioning appliances; therefore the problem remained unsolved for a long time.

Some power-driving systems for home-use knitting machines have recently been created which consist basically in an endless chain or belt designed to drive the carriage, the belt being driven by a reversible motor. In this case the carriage travel is regulated by means of adjustable reversing stops acted upon by the carriage, thus producing at each travel end a reversal of the motor drive.

This power drive for home knitting machines however has in practice proved to be an unsatisfactory solution. To begin with, the required drive is more complicated, more expensive and more sensitive to wear and tear than a common continuous power drive. Furthermore, constant reversing operations, performedby the motor as well as by the entire driving device, subject all these parts to vibrations and to wear and tear, preventing the carriage in the long run from travelling uniformlyrAlso permanent adjustment of the carriage- 'travel limiting stops is requiredin order to adjust the travel to the possibly modified fabric width.

Virtual failure of all attempts to solve the problem,

could be dispensed with, leaving the carriage to travel in each run over the whole length of the machine, regardless of the fabric width to be knit, and even regardless of the location of the fabric on the machine.

Consequently, the inventive thread-feeding, tensionregulating device was created which is able to take up the thread dispensed in excess when the carriage travels in an idle run over the whole length of the machine, but supplying a virtually uniform feeding tension.

This solution is one of the major features of the present invention. Experiments performed with various embodiments have proved satisfactory. I

The new thread-feeding, tension-regulating device, applicable to generally all knitting-machine types, is essentially constituted by a supplemental tensioning arm mounted in an articulated manner by one of its ends, whereas the opposite, free end includes a supplemental threading member. The tensioning arm consists normally of a light and relatively elastic bar which is submitted to the action of resilient means which tend to lift the free end of the tensioning arm.

The invention is mainly characterized in that a device, designed to multiply the respective displacements,

is interposed between the movable application point of the above-mentioned resilient means and the application point of the pressure exerted against the body of the supplemental tensioning arm.

In accordance with various experiments this new thread-feeding, tension-regulating device may be built in several ways. It is adapted however in all cases to the essential characteristics of the invention as defined above.

Thus, one of the preferred exemplary embodiments of the invention consists in that the articulated end of the supplemental tensioning arm is united with the shaft of a small gear connected to a toothed rack or segment, formed as a circular bow of a substantially longer radius than that of the small gear, the shaft of the gear being mounted rotatably on the end of at least one guide rod, the opposite end of which is mounted in an articulated manner, coinciding with the geometrical center of the circular bow. The guide rod or rods are submitted to the action of biasing means which tend to cause the guide rod or rods to rotate about the articulated mounting.

Thus a very small displacement of the movable support point of the biasing means on the guide rod or rods is matched by an equivalent angular displacement of said guide rod around its mounting, which corresponds to an equal angular displacement of the small-gear shaft with regard to the center of the circular rack.

However, due to the differences between the radii of the rack and of the small gear as well as the epicycloidal travel of the latter, the angular displacement of the small-gear shaft about itself becomes much larger, on account of so much larger an angular displacement being performed by the articulated arm of the tensionregulating device.

In another form of the invention the supplemental tensioning arm is united with a rotatably mounted small gear, and a multiplication gear train is interposed bearm is designed to consist of a firstor second-degree lever the power arm of which has to be substantially shorter than the other arm.

The multiplication of the device may evenbe increased by means of two serially connected levers in such a way that the multiplication effect of the first lever will in turn be further multiplied by the second lever.

Summarizing, the invention consists in interposing a device designed to multiply displacements between the movable application point of the resilient means and the application point of the pressure exerted on the body of the supplemental tensioning arm, in such a way that the latter performs a noticeable angular displacement, resulting from a very small displacement performed by the movable application point of the resilient means, designed to cause the pressure exerted by the latter along the angular displacement of the supplemental tensioning arm to remain virtually uniform.

A possibility has also been provided within the scope of the invention to regulate the pressure exerted by the resilient means in such a way that the thread-feeding tension may be adapted to various types of threads and fabrics.

Other objects and many of the attendant advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered with the accompanying drawings, wherein FIG. 1 is a side view of one of the preferred, exemplary forms of the inventive thread-feeding, tensionregulating device, with a supplemental tensioning arm in the upper end position;

FIG. 2 is likewise a side view of the same device but with its arm in the lower end position;

FIG. 3 is an elevation of the device of FIGS. 1 and 2;

FIG. 4 shows a front perspective of the same device;

FIG. 5 shows an overall perspective view of the inventive exemplary device of FIGS. 1 to 4 when applied to a home-use knitting machine which is mounted on a support bench and equipped with a power drive;

FIG. 6 isa partial side view of the arrangement in FIG. 5, with different operational phases being illustrated;

FIG. 6a shows an enlarged portion of FIG. 6, partly in section;

' FIG. 7 shows a portion of the machine-carriage driving device of FIG. 5; I

FIG. 8 is a wiring diagram of a preferred electrical circuit designed to drive the electric motor of the machine;

FIG. 9 shows a partial side view of another exemplary form of the inventive tension-regulating device, with a multiplication gear train; and

FIG. 10 shows a partial side view of yet another embodiment of the tension-regulating device, this time based on a first-degree lever designed to multiply the displacement.

The revolutionary principle underlying the present invention will be illustrated in three practical exemplary embodiments, namely in FIGS. 1 through 4, and also shown in FIGS. 5 and 6 on a home-type knitting machine, generally identified by numeral 15; then in a modified or second. form, denoted generally by numeral 15A, in FIG. 9; and finally in yet another structural example, identified by numeral 15B and illustrated in FIG. 10. The three examples clearly show that the inventive concept has a wide area of applicability and is suitable for practically all knitting machines of the general type described hereinabove. I

The thread-feeding, tension-regulating device 15, as shown in FIGS. 1 through 7, basically consists of a vertical support structure 1 united with a carriage 2 (see FIGS. 5, 6, 7) of a knitting machine 3, such as any one fixed which latter engages rack 6.

As will be described later in more detail, machine 3 FIGS. 5 and 6) has a conventional tensioning arm 46 with a threading member 46a formed at the free end of the former. So far as the inventive tension-regulating device is concerned, on one end 12' of shaft 12 the end 14 of a bar 16 is fixed, made of a light and elastic material, which constitutes a supplemental threadtensioning arm, with its free end formed as a supplemental threading member 16a, cooperating with the respective parts 46, 46a of the machines As will be explained later, parts 6 through 13, 16, 16a and the correlated structural elements constitute, in the described exemplary embodiment 15 of the inventive device, a multiplying device or means which is the essential part of the invention.

A helicoidal spring 17 mounted on one end of shaft 8 has an angular bend 19 on one end 18, bearing against an area 10 of one of the guide rods 10, while the opposite end 20 of spring 17 bears against an adjusting screw 21 which can be inserted and turned into any one of threaded boreholes 22 provided in part5 (in the area of toothed rack 6), allowing to adjust the tension of spring 17.

The newthread-feeding, tension-regulating device 15 of FIGS. 1 through 4 is arranged in the following way for its application to a common home-use knitting machine, as will be explained with reference to FIGS. 5 through 7.

Knitting machine 3 is fixedon a support bench 23 having a power drive. The bench incorporates an electric motor 24; by means of an interposed doublereduction pulley 27, 28 the motor transmits'by way of belts 25, 26 a rotary movement to a pulley 29 fixed on a shaft 30 which is journaled on one end of bench 23. A fixed pinion 31 mounted on shaft 30 engages another pinion 32, rotatably mounted on a shaft 33, fixed on the other end of bench 23. The pinions actuate, as bearing and driving elements, an endless chain 34.

One of the articulation bolts of chain 34 is formed as a side projection 35 (see FIG. 7) adapted to catch in a slot 36 of a depending part 37. The latter is fixed to a channel iron 38 sliding along a guiding bar 39 fixed to bench 23. This channel iron 38 is connected by means of a fishplate 40 with carriage 2 of machine 3; the lower end 1' of vertical support structure 1 is fixed on chan-' nel iron 38, as previously described.

A clew holder 41 is mounted on carriage 2 and it holds a clew or ball of thread 42 in a conventional manner. In the present case, showing an already known atrangement, a thread 43 runs from clew 42,passing through a brake formed by a spring 44 which latter presses thread 43 against a fixed surface 45.

The machine includes in the present case the earliermentioned regular tensioning arm 46 with the conventional threading element 46a on its outer or free end. The body of arm 46 is continued as a helicoidal spring 48 (see FIG. 6a) serving as an articulated mounting for the arm and having an appendix 49 on its opposite or inner end, which bears against spring 44.

This already known arrangement of arm 46 and the brake of the machine cause appendix 49 to counteract spring 44 only after arm 46 has reached its lower end position (solid-line showing in FIG. 6), thus allowing thread 43 to wind off holder 41. Beyond said position of arm 46 springs 44 prevents thread 43 from winding off clew 42.

The need for more thread will consequently entail the lowering of regular tensioning arm 46 until it reaches the opening position of spring 44. Thread 43 when winding off clew 42 passes through the brake formed by spring 44 and over surface 45, passing subsequently through threading member 46a of arm 46 of the machine, and thereafter through supplemental threading member 16a of the inventive tensioning arm 16; then, after having passed through a thread holder 46b of carriage 2, the thread passes towards the needles of the knitting machine 3.

In accordance with the above description, the new regulating device operates in the following manner when applied to the common knitting machine as shown in FIGS. 5 through 7. When motor 24 runs, chain 34 starts its continuous displacement (later we shall see that the displacement may also be partial) in such a way that side projection 35, while travelling along the upper track ofendless chain 34, will displace parts 37, 38 and the other elements connected therewith, such as carriage 2, support structure 1, etc., towards one of the ends of the machine, whereas a displacement in the reverse direction will take place when side projection 35 travels along the lower track of chain 34. At the ends, side projection 35 slides either up or down within slot 36, as it passes about one of the pinions 31, 32, and thus from one lengthwise track to the other.

We shall analyze now the function of the new threadfeeding, tension-regulating device, according to its application as shown in FIGS. S through 7, in two extreme cases and one intermediate case of operation.

EXTREME CASE I Fabric covers the whole length of the machine. The 7 machine will knit along the whole travel of carriage 2. The original tensioning arm 46 of the machine therefore remains permanently in its lower position, being the releasing position of brake spring 44 with regard to thread 43 unwinding from clew 42. The original tensioning arm 46 thus performs but a very slight rising and lowering movement within the short travel of car-' riage 2 beyond either edge of the fabric.

The supplemental tensioning arm 16 of the new thread-feeding, tension-regulating device which in the present exemplary case does not perform any function at all correspondingly remainsall the time prac tically in its lower angular displacement position (solid line in FIG. 6), coinciding with the releasing position of the brake of original arm 46 of the machine. The supplern'ental arm 16 thus rises, together with arm 46, but

only slightly, coinciding with the end position of the carriage.

In this extreme case I, in accordance with the hypothetical operation described, the new thread-feeding device would be superfluous since carriage 2 does at no time travel beyond the edge of the fabric, namely over a distance longer than that which machine arm 46 is able to take up.

EXTREME CASE II The machine shall knit a fabric of but 5 centimeters in width, performing the knitting at one end of the machine. Let us assume that the carriage starts traveling from the end of the machine where the fabric has been arranged and that both the original and the new tensioning arms 46, 16 start from their upper, angular positions.

The carriage, starting from the end of the machine where the fabric has been arranged, travels towards the opposite end, and thus the need of thread will cause free end 16a of inventive tensioning arm 16 to perform an initial donward movement, until a point where said supplemental arm reaches such a low position that the original arm 46 is also caused to perform a downward movement to its lowest position, thereby causing thread 43 to be wound off clew 42.

When the carriage has reached the opposite end of the machine and starts the reverse travel, thread will be found to have been wound off in excess. Therefore original tensioning arm 46 will rise beyond the position where it releases brake spring 44, such rise resulting from the upward movement of new tensioning arm 16, the latter thus taking up the excess thread, as contemplated by the invention.

From FIGS. 1 through 7 it will be easily understood that if the supplemental tensioning arm 16 has'a length substantially equal to half the length of machine 3, there will be no difficulty in taking up thread produced in excess over the entire length of the machine along which the carriage traveled idly, due to the absence of fabric, and therefore said arm 16 will move from the lower (solid-line) position in FIG. 6 to a position near its upper end position (shown in broken line).

In such event, however, the movable application point at the angled portion 19 of spring 17 will have made a very small angular displacement with respect to that performed by said application point, spring 17 exerting pressure through guide rod 10 on gear 13 and therefore on supplemental arm 16. The pressure difference produced by spring 17 between the end points of displacement of the point 19 will therefore be practically negligible. Add to this that arm 16 will in practice have in its upper position (of maximum excess thread take-up, coinciding with the position of minimum tension of spring 17) a nearly vertical position (see in broken lines in FIG. 6) where the diminished tensionof spring 17 will be increased by the component resulting from the resolution of forces of the respective parallelogram.

In the lower working position, where no take-up of excess thread is performed by arm 16 and which position is substantially quite near the horizontal position of the arm (taking particularly into account the elasticity of the bar which forms the arm), the increased .tesion of spring 17 will correspondingly be diminished by the direct influence of thread tension exerted in a practically transverse direction to supplemental arm 16.

INTERMEDIATE CASE Let us assume 1.2 meters of useful machine length and a fabric being knit on its central portion over a length of 20 centimeters. Let us start from a point where carriage 2 stands at one end of the machine, in which position both arms 16 and 46 (new and old) will be at their lowest positions. At the time when carriage 2 starts its reverse travel, both arms will be caused to start an upward movement until they have taken up the 50 centimeters of thread in excess (half of the difference between 1.2 meters and 20 centimeters).

When thread holder 46b of carriage 2 arrives again at the fabric edge, new tensioning arm 16, having reached an intermediate point in its upward movement, will restart a downward movement because the carriage demands more thread. Arm 16 will continue downward movement, followed by old arm 46, to their lowest positions where arm 46 will release again the engagement between brake 44 and surface 45, allowing more thread 43 to be wound off clew 42. In this lower position the arms will arrive at the opposite end of the machine. I

This operation will be repeated when carriage 2 per forms another reverse travel. The thread-feeding tension will be the same at any given moment as in both preceding cases.

These three exemplary operational cases of the new thread-feeding, tension-regulating device demonstrate that the user need not worry about either the width or the location of the fabric on themachine, resulting in simplicity and comfort. This means that a knit fabric can be attained having a uniform feeding tension, and without the need of previous adjustments of the carriage travel.

The inventive device shown in FIGS. 5 through 7 may be applied to knitting machines without the need of any changes thereof. Particularly clew holder 41, original tensioning arm 46 and braking device 44, 45 remain unchanged on the machine.

This way of applying the new regulating device offers severalpractical advantages. Firstly, no change need be made on a factory-made knitting machine; secondly, advantage and economy may be derived from using the original clew holder and braking device. And finally, whenever the knitting machine is to be used with manual operation, disconnection of fishplate 40, which connects channel iron 38 with carriage 2, will suffice in order to use the machine in its original hand-actuated manner, dispensing this time with supplemental tensioning arm 16 and the other elements which do not form part of the original knitting machine. However, arm 16 may be used when actuating the machine by hand, and in such an event this arm need merely be mounted directly onto carriage 2.

However the new thread-feeding, tension-regulating device may of course be built with its own clew holder and brake, whichlatter may be of the type as shown and described before or of any other known type, and in such an event the original clew holder, brake and tensioning arm of the knitting machine are to be dispensed with.

The wiring diagram of FIG. 8 has been included merely to show that the power drive of a home-use knitting machine can be provided in accordance with means already known, and for the purpose of the present invention, either by way of a continuous drive, such as would be desirable when a fabric of an unchanged width and pattern are knit, or by way of a discontinuous. drive, such as would be required when changes are to be made between carriage travels, e.g., for increasing or reducing the fabric width, for open-work fabrics, ornamental designs, etc.

In the wiring diagram of FIG. 8 is shown a mains supply 51 for alternating current, where a master switch 52 regulates the supply for an electric motor 53 fitted with a brake 54. Numeral 55 denotes a series-connected pedal switch, 56 a hand-actuated switch; 57 is a relay with an armature 58; 59a, 59b are limit switches actuated for example by the machine carriage at the endof each travel marked by respective arrows 2a,.2b.

A person skilled in the art will readily understand that upon closing of main switch 52, the closing of the circuit by means of pedal switch 55 while handactuated switch 56 remains open will suffice in order to cause motor 53 to operate continuously,and the carriage to travel correspondingly, until pedal switch 55 is released.

However when actuating hand switch 56 and subsequently pedal switch 55 for a short time motor 53 is caused to start operating and at the same time relay 57 is excited and its armature 58 allows current to be supplied. Carriage 2 starts traveling as shown by the arrows, and upon arriving at the end of the travel, it will actuate one of the limit switches 59a or 59b. As pedal, switch 55 had already been released, this will cause.

delay 57 to drop and motor 53 to stop, and with it carriage 2 at one of the travel ends, thus allowing the attendant to perform changes, such as reductions, etc. on the machine before having the carriage start the following travel. I

The foregoing explanations, regarding the preferred embodiment '15 of the inventive device as shown in similar structural parts. I

FIG. 9 shows thatin the modified device A supplemental tensioning arm 16 has one end 14 fixed to small gear 13 rotatably mounted on shaft 12 which is mounted. on a base plate 4". Helicoidal spring 17 is mounted on a pin 8' fixed onto base plate 4" and has its end 18 form the'bend 19, moving within a slot 63 of a disk 64 provided with a toothed segment 65 and rotatably mounted on a fixed shaft 66. Opposite end 20 of spring 17 bears against adjusting screw 21 adapted to be partially screwed into any one of bores 22 on base plate 4".

An intermediate and multiplying double gear 67, 68, rotatably mounted on a fixed shaft 69, transmits the angular displacement of disk 64 with segment 65 to gear 13, thereby multiplying the relative magnitude of such angular displacements. As we have seen in FIGS. 1 to 7, in the modified form of the invention shown in FIG. 9 a small displacement of movable support 19 of spring 17 will also be matched, as shown'by the solid and the dashed lines in that figure, by a highly multiplied or enlarged displacement of supplemental tensioning arm 16, with results equivalent to those of the basic embodiment of FIGS. 1 to 7.

The same happens in yet another exemplary embodiment of the inventive device, shown in FIG. 10 under the general designation 15B, where bent end 19 of arm 18 of spring 17, mounted on pin 8, exerts a pressure against the end of a first-degree lever 71 articulated on a shaft 72 which is rotatably mounted on base plate 4". The end 73 of an opposite arm 74 of lever 71 slid ingly passes through a borehole of an appendix 75 which is rotatably mounted on a projection 76 of arm 16, itself rotatably mounted on shaft 12 which is here again fixed on base plate 4'', audit will also multiply the angular displacement of arm 18 of spring 17, transforming it into an angular displacement of supplemental tensioning arm 16 about its mounting articulation (shaft) 12. Elements 70 to 76 of the machine constitute multiplying means wherein first-degree lever 71 has respective power" and resistance arms at the ends 70 and 74, the former being preferably substantially shorter than the latter, for the reasons explained hereinabove. Y

It will be easily understood that in accordance with the above description and the accompanying illustrations of the new thread-feeding, tension-regulating device, applicable to home-use knitting machines, the new device may also be used with industrial knitting machines in which case the special travel-limiting device for the carriage on the thread holder, designed to be adapted to the width of the fabric, may be completely dispensed with. This entails not only a signifi cant economy but also an important simplification in the handling and maintenance of the knitting machines.

It should be understood, of course, that the foregoing disclosure relates only to preferred, exemplary embodiments of the invention, and that it is intended to cover all changes and modifications of the examples described which do not constitute departures from the spirit and scope of the invention.

What we claim is: g

1. A thread-feeding, tension regulating device for straight knitting machines (3) which latter include a reciprocable carriage (2), a thread-tensioning arm (46) and a threading member (46a) at the free end of the latter, the tension-regulating device comprising a supplemental thread-tensioning arm (16) having a body andbeing articulated by one end (14) while the other, free end has a supplemental threading member (16a) thereon, resilient means (17) for biasing said supplemental tensioning arm, said resilient means tending to lift said free end of the supplemental tensioning arm and having a movable application point (10', 19), and means (6 to 13; 63 to 69; 70 to 76) interposed between said movable application point of the resilient means and an application point (13; 63; 75) of its pressure on said body of the supplemental tensioning arm, for mul plemental tensioning arm performs a noticeable angular displacement as a result of a very small displacement performed by said movable application point, in order that said pressure exerted by the resilient means remains virtually uniform along the path of said angular displacement.

2. The tension-regulating device as defined in claim 1, wherein said supplemental tensioning arm (16) has a length substantially equal to half the operative length of the knitting machine (3).

3. The tension-regulating device as defined in claim 1, further comprising means (20 to 22) for regulating said pressure exerted by said resilient means (17) on said supplemental tensioning arm (16).

4. The tension-regulating device as defined in claim 3, wherein said regulating means (20 to 22) includes a member (21) associated with one end (20) of said resilient means (17), adapted to be engaged in one of a plurality of holes (22) provided in a stationary member (5).

5. The tension-regulating device as defined in claim 1, wherein the knitting machine (3) further includes a clew holder (41), a braking device (44, 45)'and another threading member (46b) on said carriage (2), for the thread (43) to be knit, the tension-regulating device further comprising means for guiding the thread along a path from said clew holder to said other threading member by way of said braking device and said supplemental threading member (16a).

6. The tension-regulating device as defined in claim 5, wherein said guiding means further includes in said path of the thread (43) said first-named threading member (46a) of the knitting machine (3) between said braking device (44, 45) and said supplemental threading member (16a).

7. The tension-regulating device as defined in claim 1, further comprising a supplemental clew holder and a supplemental braking device structurally associated therewith, through which the thread (43) passes before reaching said supplemental threading member (16a).

8. The tension-regulating device as defined in claim 1, wherein said one end (14) of the supplemental tensioning arm (16) is solid with a small gear (13) forming part of said multiplying means (6 to 13) and being connected to an arcuate toothed segment (6) of a substantially longer radius than that of said small gear, a shaft (12) of the latter being rotatably mounted on the end ll) of at least one guide rod (10) also part of said multiplying means, the opposite end (9) of said guide rod being articulated to and coinciding with the geometrical center of said segment, said at least one guide rod being submitted to the action of said resilient means (17) which tends to rotate said guide rod about its articulated mounting (8).

9. The tension-regulating device as defined in claim 8, wherein said shaft (12) of the small gear (13) is rotatably mounted on the ends (11) of two of said guide rods (10), said opposite ends (9) of the latter being articulated to a shaft (8) coinciding with the geometrical axis of said segment (6) while said resilient means (17) is constituted by a helicoidal spring connected to said articulated mounting (8), one end of said spring forming an arm (18) with an angular portion (19) which, acting as said movable application point (10', 19), bears against the lower edge of one of said guide rods, while the opposite arm (20) of said spring bears against an adjustable stop (21) mounted on a stationary part (5) on which is formed said segment.

10. The tension-regulating device as defined in claim 1, wherein said supplemental tensioning arm (16) is solid with a rotatably mounted small gear (13) forming part of said multiplying means (63 to 69), the latter further including a multiplication gear train (65, 67, 68) interposed between said movable application point (19) and said small gear.

11. The tension-regulating device as defined in claim 1, wherein said multiplying means (70 to 76) further includes an articulated (72) lever (71) having respective power (70) and resistance arms (74), said power arm being substantially shorter than said resistance arm, the latter acting on said supplemental tensioning arm (16).

Claims (11)

1. A thread-feeding, tension-regulating device for straight knitting machines (3) which latter include a reciprocable carriage (2), a thread-tensioning arm (46) and a threading member (46a) at the free end of the latter, the tension-regulating device comprising a supplemental thread-tensioning arm (16) having a body and being articulated by one end (14) while the other, free end has a supplemental threading member (16a) thereon, resilient means (17) for biasing said supplemental tensioning arm, said resilient means tending to lift said free end of the supplemental tensioning arm and having a movable application point (10'', 19), and means (6 to 13; 63 to 69; 70 to 76) interposed between said movable application point of the resilient means and an application point (13; 63; 75) of its pressure on said body of the supplemental tensioning arm, for multiplying the respective displacements so that said supplemental tensioning arm performs a noticeable angular displacement as a result of a very small displacement performed by said movable application point, in order that said pressure exerted by the resilient means remains virtually uniform along the path of said angular displacement.

2. The tension-regulating device as defined in claim 1, wherein said supplemental tensioning arm (16) has a length substantially equal to half the operative length of the knitting machine (3).

3. The tension-regulating device as defined in claim 1, further comprising means (20 to 22) for regulating said pressure exerted by said resilient means (17) on said supplemental tensioning arm (16).

4. The tension-regulating device as defined in claim 3, wherein said regulating means (20 to 22) includes a member (21) associated with one end (20) of said resilient means (17), adapted to be engaged in one of a plurality of Holes (22) provided in a stationary member (5).

5. The tension-regulating device as defined in claim 1, wherein the knitting machine (3) further includes a clew holder (41), a braking device (44, 45) and another threading member (46b) on said carriage (2), for the thread (43) to be knit, the tension-regulating device further comprising means for guiding the thread along a path from said clew holder to said other threading member by way of said braking device and said supplemental threading member (16a).

6. The tension-regulating device as defined in claim 5, wherein said guiding means further includes in said path of the thread (43) said first-named threading member (46a) of the knitting machine (3) between said braking device (44, 45) and said supplemental threading member (16a).

7. The tension-regulating device as defined in claim 1, further comprising a supplemental clew holder and a supplemental braking device structurally associated therewith, through which the thread (43) passes before reaching said supplemental threading member (16a).

8. The tension-regulating device as defined in claim 1, wherein said one end (14) of the supplemental tensioning arm (16) is solid with a small gear (13) forming part of said multiplying means (6 to 13) and being connected to an arcuate toothed segment (6) of a substantially longer radius than that of said small gear, a shaft (12) of the latter being rotatably mounted on the end (11) of at least one guide rod (10) also part of said multiplying means, the opposite end (9) of said guide rod being articulated to and coinciding with the geometrical center of said segment, said at least one guide rod being submitted to the action of said resilient means (17) which tends to rotate said guide rod about its articulated mounting (8).

9. The tension-regulating device as defined in claim 8, wherein said shaft (12) of the small gear (13) is rotatably mounted on the ends (11) of two of said guide rods (10), said opposite ends (9) of the latter being articulated to a shaft (8) coinciding with the geometrical axis of said segment (6) while said resilient means (17) is constituted by a helicoidal spring connected to said articulated mounting (8), one end of said spring forming an arm (18) with an angular portion (19) which, acting as said movable application point (10'', 19), bears against the lower edge of one of said guide rods, while the opposite arm (20) of said spring bears against an adjustable stop (21) mounted on a stationary part (5) on which is formed said segment.

10. The tension-regulating device as defined in claim 1, wherein said supplemental tensioning arm (16) is solid with a rotatably mounted small gear (13) forming part of said multiplying means (63 to 69), the latter further including a multiplication gear train (65, 67, 68) interposed between said movable application point (19) and said small gear.

11. The tension-regulating device as defined in claim 1, wherein said multiplying means (70 to 76) further includes an articulated (72) lever (71) having respective power (70) and resistance arms (74), said power arm being substantially shorter than said resistance arm, the latter acting on said supplemental tensioning arm (16).

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