US3789631A

US3789631A - Yarn tension control device

Info

Publication number: US3789631A
Application number: US00224424A
Authority: US
Inventors: J Deniega
Original assignee: Stop Motion Devices Corp
Current assignee: DURKIN WILLIAM N; Stop Motion Devices Corp; IRO Inc
Priority date: 1972-02-08
Filing date: 1972-02-08
Publication date: 1974-02-05
Anticipated expiration: 1991-02-05
Also published as: JPS4887148A; FR2171720A5; DE2256375B2; ES407953A1; DE2256375A1; JPS5131863B2; IT967882B; GB1409322A

Abstract

A yarn tension control device having yarn tension sensing means adapted to support the travelling yarn, which sensing means is secured to a shaft which terminates in a crank portion. Spring means connected at one end thereof to the crank portion urge the yarn tension sensing means into a normal yarn supporting position against the resistance of the yarn tension. The other end of the spring is secured to the free end of a tension control lever whose opposite end is mounted for pivotal movement. The lever is straddled by a channeled block and has a bottom curved surface which defines a cam follower and cam combination with the block, whereby longitudinal movement of the block causes pivotal movement of the lever for varying the tension on the spring.

Description

United States Patent [191 Deniega [45] Feb. 5, 1974 YARN TENSION CONTROL DEVICE [75] Inventor: Jose Castillo Deniega, Elmhurst,

22 Filed: Feb. 8, 1972 21 Appl. No.: 224,424

FOREIGN PATENTS OR APPLICATIONS 811,704 4/1959 Great Britain ZOO/61.13

716,549 10/1954 Great Britain 66/163 Primary Examiner-W. C. Reynolds Assistant Examiner--A. M. Falik Attorney, Agent, or Firml-lenry R. Lerner [57] ABSTRACT A yarn tension control device having yarn tension sensing means adapted to support the travelling yarn, which sensing means is secured to a shaft which terminates in a crank portion. Spring means connected at one end thereof to the crank portion urge the yarn tension sensing means into a normal yarn supporting position against the resistance of the yarn tension. The other end of the spring is secured to the free end of a tension control lever whose opposite end is mounted for pivotal movement. The lever is straddled by a channeled block and has a bottom curved surface which defines a cam follower and cam combination with the block, whereby longitudinal movement of the block causes pivotal movement of the lever for varying the tension on the spring.

9 Claims, 8 Drawing Figures PATENIEDFEB 51974 SHEET 1 IF 2 PAIENIE FEB 5 m4 SHEET 2 (IF 2 BACKGROUND OF THE INVENTION This invention relates to a yarn tension control device for use in association with a knitting machine of the type wherein an increase in yarn tension beyond a permissible range is operative to automatically and instantaneously interrupt the knitting machine drive. An example of a yarn tension control device of the type involved herein is shown in U. S. Pat. No. 3,257,518 issued to the assignee hereofv In accordance with the device shown in US. Patent No. 3,257,518, the yarn tension is selectively adjusted by means of a relatively complex mechanism. Furthermore, such mechanism does not lend itself to a yarn tension control device wherein the yarn tension sensing means are subjected to a snap type action wherein such sensing means are spring urged into either a normal yarn supporting position or, in response to increased yarn tension, into a down position in which the yarn is discharged, and in which rethreading is more easily accomplished. The present invention, constitutes an improvement over said US. Pat. No. 3,257,518, particularly in providing improved means for adjusting the permissible yarn tension.

SUMMARY OF THE INVENTION In accordance with the present invention, the yarn tension sensing means is secured, for rotation, to a shaft which terminates in a crank portion with such crank portion having secured thereto one end of a spring, thereby defining an over the center arrangement which creates asnap action. The other end of the spring is secured to a notch at the free end of a tension control lever which is mounted for pivotal movement at its other end. The tension control lever is straddled by a channeled indicator block, and the bottom surface of the tension control lever is curved so that the indicator block and the lever define a cam and cam follower combination. In accordance with such arrangement, longitudinal movement of the indicator block, by turning a conventional screw shaft threaded through the indicator block, causes pivotal movement of the tension control lever which in turn varies the tension on the spring. Such mechanism is extremely simple in construction and yet is most effective in enabling the precise presetting of the tension on the spring which, in turn, precisely preselects the permissible range of tension for the yarn which, if exceeded, will activate the stop motion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front perspective view of the yarn tension control device, viewed from the left;

FIG. 2 is a front perspective view thereof, viewed from the right, with portions removed for purposes of illustration;

FIG. 3 is an exploded view, in perspective, of the various components, forming part ofthe tension adjustment mechanism in accordance with the invention;

FIG. 4 is a front elevational view of the device, showing the yarn tension sensing means in the down position and with parts broken away for purposes of illustration;

FIG. 5 is a top plan view of the device as shown in FIG. 4;

FIG. 6 is a view similar to FIG. 4, on an enlarged scale, with the housing cover removed for purposes of illustration;

FIG. 7 is a left side view of the device as shown in FIG. 4; and I FIG. 8 is a sectional view taken along line 8-8 of FIG. 4, shown in an enlarged scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, reference numeral 10 identifies the yarn tension control device in accordance with the invention and comprises a generally rectangular housing 12 having a removable cover plate 14 which includes a calibrated sight window 16 for reasons to be more fully described hereafter.

Extending laterally from left side wall 18 of housing 12 is a bracket 20 provided with a removable bracket cover 22. As best shown in FIG. 4, wherein bracket 20 is shown with cover 22 removed, a shaft 24 is journalled in wall 18 and depending end portion or strip 26 of bracket 20. Shaft 24 has secured thereto yarn tension sensing member 28 best shown in perspective in FIG. 3. Member 28 comprises laterally spaced

tension sensing arms

30, 32 and 34 held in spaced relation by

transverse members

36 and 38, the latter being fixedly secured to shaft 24. External sensing

arms

30 and 34 are partly encased, along their free ends, .with porcelain sheath shaped to provide smooth seats for engagement with the travelling yarn.

Shaft 24 terminates inwardly of housing 12 in a crank portion 40, to the end of which is secured one end of spring 42, the other end being secured in notch 44 of tension control lever 46. Under such arrangement spring 42 biases shaft 24 in a clockwise direction (viewing FIG. 2) corresponding to the urging of yarn tension sensing member 28 and its

sensing arms

30, 32 and 34 in an upward direction until transverse member 36 engages a stop 68 projecting inwardly of depending strip 26. Upon application of downward force to

tension sensing arms

30, 32 and 34 (in response to increased yarn tension as described hereafter) crank portion 40 will reach dead center position, after which the spring will bias shaft 24 into further counterclockwise rotation until tension sensing arm 34 engages a stop projecting outwardly of depending strip 26, defining the bottom position of sensing member 28 which is shown in FIG. 4.

Another shaft 48 is journalled in wall 18 and depending strip 26 of bracket 20, said shaft having secured thereto a generally elongated rectangular feeler member 50 provided atits rear end with a light counterweight 52. Feeler member 50 comprises

parallel arms

54 and 56 joined at their forward ends by transverse portion 58. As best seen in FIGS. 1 and 2,

arms

54 and 56 are movable between thetension sensing arms of tension sensing member 28. The dimensions of the forwardly extending portions of feeler member 50 are such that in spite of the counterweight 52, the feeler member is urged into clockwise movement viewing FIG. 1, i.e., corresponding to downward movement of the forward portions of arms 54 and S6. Feeler member carrying shaft 48 terminates inwardly of housing 12 whereat it carries a segmented electrical contact member 60 rotatable therewith. Bracket cover 22 is provided with a stationary wire formation 62 comprising spaced inverted

V portions

64 and 66 whose apexes define guide means for the yarn.

During normal operation of devide 10, as best shown in FIG. 1 and the full lines in FIG. 8,

tension sensing arms

30, 32 and 34 are maintained by spring 42 in their uppermost position defined by the engagement of transverse member 36 with stop 68, the yarn travelling from the supply thereof is guided over the sensing arms by wire formation 62 and the yarn supports

arms

56 and 58 of feeler member 50. In the event of an increase in yarn tension of sufficient magnitude to overcome the force exerted by spring 42, tension sensing member 28 moves downwardly, causing rotation of crank portion 40 until the dead center position thereof, beyond which the spring will urge member 28 onto its down position defined by the engagement of tension sensing arm 34 and stop 70 as shown by the full lines in FIG. 7, permitting the yarn to slip off before breakage. As the yarn slips off, the forward portions of

arms

54 and 56 lose support by the yarn and move downwardly, causing rotation of its shaft 48 and of electrical contact member 60 which is rotatable therewith. As best seen in FIG. 2 and FIG. 8, an electrical contact strip 72 is provided internally of housing 12, being secured to an insulating block 74 by means of rivets 76. Strip 72 terminates in a free end portion 78 immediately below segmented electrical contact member 60. As best shown by the solid line inFIG. 8, when feeler member 50 is supported by yarn Y during normal operation, the flat bottom surface 80 of contact member 60 is substantially horizontal and thus in spaced relation to end portion 78 of electrical contact strip 72. When, as described above, increased yarn tension causes slippage of the yarn from sensing member 28, as shown by the dashed lines in FIG. 8, feeler member 50, being no longer supported by the yarn, is biased into counterclockwise position, viewing FIG. 8, until bottom surface 80 of contact member 60 engages contact strip 78 which also defines a yielding stop for the movement of feeler member 50. A further stop is defined by engagement of rear portion of

arms

54 and 56 with bracket 20. The engagement of contact member 60 with contact strip 72 completes a circuit through signal light 82 and to tenninal 84. It will be understood that electrical connections from terminal 84 to conventional electrical control means will be operative, upon completion of said circuit, to discontinue rotation of the knitting machine to which yarn Y is being supplied and to light lamp 82. An example of such electrical connections is shown in U.S. Pat. No. 3,00l,389 assigned to the assignee hereof. It will also be noted that in the event of yarn breakage, feeler member 50 will similarly be urged into the position shown by the dashed lines in FIG. 8 to complete an electrical circuit to the stop motion.

In accordance with the invention, there is provided novel means for selectively adjusting the permissible yarn tension range beyond which the stop motion is to be activated. Such adjustment is clearly a function of the tension of spring 42 whose opposing force must be overcome before downward movement of tension sensing member 28 can take place in response to increased yarn tension. Thus, if such spring tension is low, a slight amount of increased yarn tension will be operative to activate the stop motion. On the other hand, if the spring is under substantial tension, a greater amount of yarn tension will be required to activate the stop motion.

In accordance with the invention, there is provided a novel means for selectively adjusting the spring tension from a minimum magnitude to a maximum magnitude in order to accommodate all different types of yarn under all different types of knitting conditions. As previously stated, and as best shown in FIGS. 2 and 6, spring 42 is secured at one end to crank portion 40 and at the other end to notch 44 at one end of tension control lever 46. Tension control lever 46 is pivotally mounted at its other end to the housing by means of pivot pin 86. Bottom surface 88 of lever 46 is curved so that suchlever increases in height from the pivot pin to the notched end. An indicator block 90 is channeled as at 92 to straddle tension control lever 46 so that the latter is supported by engagement of bottom surface 88 with edge 94 of the channel. A fine screw shaft 96 extends into the housing 12 through bracket 20, the bracket and side wall 18 of the housing having apertures defining bearings for an unthreaded portion 98 of the shaft, which carries a knurled knob 100 externally of the bracket. Block 90 has a threaded aperture 102 for receiving screw shaft 96 and a clip 104 secures shaft 96 against axial movement. A platform 106 is provided within housing 12 for supporting block 90 for lateral movement in response to rotation of screw shaft 96, in response to the rotation of knob 100. Accordingly, as block 90 is moved leftward, viewing the figures, edge 94 of slot 92 will engage bottom surface 88 of tension control lever 46 so as to cause clockwise rotation thereof, thus increasing the tension on the spring. Conversely, rightward movement of the block will cause counterclockwise movement of tension control lever 46 reducing the amount of tension applied to the spring. Block 90 therefore defines, in combination with tension control lever 46, a cam and cam follower, respectively, for adjusting the tension on spring 42. A pair of spaced stops 108 and 110, mounted on the rear wall of housing 12, define the extreme positions of block 90. A pin 112 projects forwardly of block 90 and defines an indicator which cooperates with the calibrations on sight window 16 so that the device can be selectively preadjusted to a desired tension and so that a plurality of devices mounted on the same machine can all be adjusted to the same preselected tension. It will be understood that in accordance with the invention, curvature of bottom surface 88 can be chosen to correspond to any desired relationship between the lateral movement of the indicator block and the corresponding increases in tension beyond which the stop motion is intended to be operative.

Housing 12 is provided with bracket 114 adapted for securement to a carrier having a toggle clamp so that yarn tension control device 10 can be mechanically and electrically connected to the knitting machine in a manner similar to that shown in U.S. Pat. No. 3,257,518 assigned to the assignee hereof.

While there is herein shown and described the preferred embodiment of the invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that in the illustrated embodiment certain changes in the details of construction and in the form and arrangement of parts may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by letters patent is:

l. Yarn tension control means for controlling the tension in yarn travelling from a source of supply to a work station on a knitting machine comprising:

a. yarn tension sensing means adapted to support said travelling yarn,

b. a shaft secured to said yarn tension means and terminating in an end portion,

c. spring means connected at one end thereof to said end portion and urging said yarn tension sensing means into a normal yarn supporting position against the resistance of the yarn tension,

(1. said yarn tension sensing means being movable from said normal position thereof to another position thereof in response to an increase in the travelling yarn tension which exceeds the resistance of the spring biasing force,

e. and means for selectively adjusting said spring biasing force for correspondingly selecting the predetermined yarn tension which will cause movement of said yarn tension sensing means from said normal position thereof to said another position thereof,

. said adjusting means comprising,

1. atension control lever having opposite ends, the other end of said spring being secured adjacent one end of said lever, and said lever being mounted for pivotal movement adjacent the other end thereof,

2 and means disposed between said oppositeends of said tension control lever and operatively related to said tension control lever and adapted, when movably actuated, to pivotally move said control lever whereby to vary the tension on said spring, said operatively related means being mounted for slidingly engaging movement relative to said control lever.

2. Yarn tension control means in accordance with claim 1, wherein said tension control lever has a curved bottom surface imparting to said lever increasing height from said other end thereof to said one end thereof, and wherein said means operatively related to said tension control lever comprises a block having a channel straddling said lever and engaging said curved bottom surface, whereby said block and control lever define a cam and cam follower, respectively, wherein predetermined movement of said block causes predetermined pivotal movement of said tension control lever.

3. Yarn tension control means in accordance with claim 2, wherein said block is provided with a threaded aperture for receiving a screw shaft held against axial movement, whereby rotation of said screw shaft imparts longitudinal movement to said block to, in turn, impart pivotal movement to said tension control lever for varying the spring tension.

4. Yarn tension control means in accordance with claim 3, wherein said block is provided with an indicator which cooperates with a stationary calibrated scale.

5. Yarn tension control means in accordance with claim 1, wherein said shaft end portion comprises a crank whereby rotation thereof in response to increased yarn tension past dead center causes said spring tourge said yarn tension sensing means into said another position in which the travelling yarn is discharged.

6. Yarn tension control means in accordance with claim 5, wherein there is provided a feeler adapted to be supported by the travelling yarn when the latter is normally supported by said yarn tension sensing means, said feeler being movable in response to yarn absence to a position in which it is operative to cause the activation of a stop motion for interrupting the knitting machine drive.

7. Yarn tension control means in accordance with claim 6, wherein said tension control lever has a curved bottom surface imparting to said lever increasing height from said other end thereof to said one end thereof, and wherein said means operatively related to said tension control lever comprises a block having a channel straddling said lever and engaging said curved bottom surface, whereby said block and control lever define a cam and cam follower, respectively, wherein predetermined movement of said block causes predetermined pivotal movement of said tension control lever.

8. Yarn tension control means in accordance with claim 7, wherein said block is provided with a threaded aperture for receiving a screw shaft held against axial movement, whereby rotation of said screw shaft imparts longitudinal movement to said block to, in turn, impart pivotal movement to said tension control lever for varying the spring tension.

9. Yarn tension control means in accordance with claim 8, wherein said block is provided with an indicator which cooperates with a stationary calibrated scale. r=

Claims

1. Yarn tension control means for controlling the tension in yarn travelling from a source of supply to a work station on a knitting machine comprising: a. yarn tension sensing means adapted to support said travelling yarn, b. a shaft secured to said yarn tension means and terminating in an end portion, c. spring means connected at one end thereof to said end portion and urging said yarn tension sensing means into a normal yarn supporting position against the resistance of the yarn tension, d. said yarn tension sensing means being movable from said normal position thereof to another position thereof in response to an increase in the travelling yarn tension which exceeds the resistance of the spring biasing force, e. and means for selectively adjusting said spring biasing force for correspondingly selecting the predetermined yarn tension which will cause movement of said yarn tension sensing means from said normal position thereof to said another position thereof, f. said adjusting means comprising, 1. a tension control lever having opposite ends, the other end of said spring being securEd adjacent one end of said lever, and said lever being mounted for pivotal movement adjacent the other end thereof, 2. and means disposed between said opposite ends of said tension control lever and operatively related to said tension control lever and adapted, when movably actuated, to pivotally move said control lever whereby to vary the tension on said spring, said operatively related means being mounted for slidingly engaging movement relative to said control lever.

2. and means disposed between said opposite ends of said tension control lever and operatively related to said tension control lever and adapted, when movably actuated, to pivotally move said control lever whereby to vary the tension on said spring, said operatively related means being mounted for slidingly engaging movement relative to said control lever.

5. Yarn tension control means in accordance with claim 1, wherein said shaft end portion comprises a crank whereby rotation thereof in response to increased yarn tension past dead center causes said spring to urge said yarn tension sensing means into said another position in which the travelling yarn is discharged.

9. Yarn tension control means in accordance with claim 8, wherein said block is provided with an indicator which cooperates with a stationary calibrated scale.