Title:
TENSION METERS
United States Patent 3879999


Abstract:
Shown is a tension meter comprising a base, a pair of spaced filament engaging members fixed with respect to each other and each having a filament engaging surface, a third filament engaging member movably mounted on the base and disposed between the pair. The third member is movable in a plane perpendicular to a reference line tangent to those surfaces of the pair. The three members are adapted to engage one or a multiplicity of filaments with the pair of members and the third member disposed on opposite sides of the filament(s). Means are provided connected to the third member for indicating the magnitude of its motion. Biasing means cause the third member to deflect a filament engaged by said members from a straight path. Damping means, for damping tension fluctuations transferred from the filament(s) to the third member, are provided and comprise a cylinder, a piston disposed within the cylinder for sliding motion, means connecting the piston with the third member, and an adjustable valve in the cylinder.



Inventors:
SAXL ERWIN J
Application Number:
05/356349
Publication Date:
04/29/1975
Filing Date:
05/02/1973
Assignee:
SAXL; ERWIN J.
Primary Class:
Other Classes:
73/430, 73/862.472
International Classes:
G01L5/06; (IPC1-7): G01L5/06
Field of Search:
73/144,430
View Patent Images:
US Patent References:
3512406TENSION METER1970-05-19Roberts
3495454DEVICE FOR ELECTRICALLY MEASURING THE TENSION OF MOVING THREADS1970-02-17Heimes
2723561Tensiometer1955-11-15Chaya et al.
2591724Tension meter1952-04-08Saxl
2245039Tension meansuring device1941-06-10Lilja



Primary Examiner:
Ruehl, Charles A.
Claims:
I claim

1. A tension meter comprising a base, a pair of spaced filament engaging members fixed with respect to each other and each having a filament engaging surface, a third filament engaging member movably mounted on said base and disposed between said pair, said third member movable in a plane perpendicular to a reference line tangent to said surfaces of said pair, said members being adapted to engage a filament with said pair of members and said third member disposed on opposite sides of the filament, means connected to said third member for indicating the magnitude of its motion, first biasing means operative to cause said third member to deflect from a straight path of filament engaged by said members, and damping means for damping vibrations of said third member in said plane, said damping means comprising a cylinder, a piston disposed within said cylinder for sliding motion, means operatively connecting said piston with said third member, and an adjustable valve in said cylinder.

2. A tension meter as claimed in claim 1 wherein said connecting means comprises a first member attached to said third filament engaging member and including a portion spaced apart from said third filament engaging member whereby said portion undergoes movement proportional to, but greater than, the motion of said third filament engaging member.

3. A tension meter as claimed in claim 2 wherein said connecting means further comprises a second member comprising a rod attached in a universal joint to each of said piston and said connecting means first member portion.

4. A tension meter as claimed in claim 1 wherein said pair of spaced filament engaging members are mounted upon a support, said support being movably mounted on said base for movement between first and second positions, the filament engaging surface of said third filament engaging member lying on one side of said reference line when said support is in said first position and on the other side of said reference line when said support is in said second position.

5. A tension meter as claimed in claim 4 further including second biasing means biasing said support towards said first position.

6. A tension meter as claimed in claim 4 wherein said pair of members are mounted on a convexly curved surface, whereby friction against moving yarns is reduced.

7. A tension meter as claimed in claim 6 wherein said connecting means comprises a first member attached to said third filament engaging member and including a portion spaced apart from said third filament engaging member whereby said portion undergoes movement proportional to, but greater than, the motion of said third filament engaging member, said connecting means first member extending tangentially from said convexly curved surface.

8. A tension meter as claimed in claim 1 wherein said adjustable valve comprises an opening in said cylinder, barrier means mounted for movement with respect to said opening, and means for moving said barrier to alter the portion of said opening effectively masked by said barrier.

9. A tension meter comprising a base, first and second filament engaging members fixed with respect to each other and each having a filament engaging portion, said first and second spaced filament engaging members mounted upon a support, said support including a convexly curved surface from which said members project, a third filament engaging member movably mounted on said base and disposed between said first and second members, said members being adapted to engage a plurality of adjacent generally parallel filaments with said first and second members on one side of the filaments and said third member on the other side of the filaments, said support movably mounted on said base for movement between first and second positions, said third filament engaging member lying on one side of a reference line tangent to said filament engaging portions at the intersection thereof with said support when said support is in said first position and on the other side of said reference line when said support is in said second position, at least one of said first and second members including structure giving that member a substantial thickness in a direction generally perpendicular to said reference line, whereby insertion of said one of said members between two of a plurality of parallel filaments for measurement of the tension in a smaller plurality of said filaments causes the filaments included in said smaller plurality to be spaced apart from other filaments thus permitting the insertion of the other of said first and second members between the same two filaments, said tension meter further comprising damping means for damping vibrations of said third member, said damping means comprising a cylinder, a piston disposed within said cylinder for sliding motion, means operatively connecting said piston with said third member, and an adjustable valve in said cylinder.

10. The improvement as claimed in claim 9 wherein said connecting means comprises a first member attached to said third filament engaging member and including a portion spaced apart from said third filament engaging member whereby said portion undergoes movement proportional to, but greater than, the motion of said third filament engaging member, said connecting means first member extending tangentially from said convexly curved surface.

11. In a tension meter comprising a base, first and second filament engaging members fixed with respect to each other and each having a filament engaging section and an end section, each said filament engaging section being mounted upon a support and including a filament engaging surface, said surfaces defining a reference line tangent to each said surface at the intersection thereof with said support, said support including a convexly curved surface from which said members project, a third filament engaging member mounted on said base and disposed between said first and second members, said support movably mounted on said base for movement between first and second positions, said third filament engaging member lying one one side of said reference line when said support is in said first position and on the other side of said reference line when said support is in said second position, said members being adapted to engage a plurality of adjacent generally parallel filaments with said first and second members on one side of the filaments and said third member on the other side of the filaments,

Description:
BACKGROUND OF THE INVENTION

This invention relates to meters for measuring tension in filamentary materials, such as yarns or wires. It is also useful to check the fluctuating tensions of tapes and films such as when they are varied in a motion picture camera during the intermittent sprocket action.

The improvements described herein are particularly suitable for incorporation into tension meters of the general type described in my previous U.S. Pat. Nos. 2,591,724; 3,177,708; 3,344,664; and 3,398,575.

As used herein the word "filaments" is intended to encompass both truly filamentary materials and relatively thin webs such as slit tapes and films which, as will be apparent to those skilled in the art, are susceptible to have their tension measured by apparatus of this type described herein. Furthermore, to facilitate the discussion, the filaments with which the apparatus is being used will often be assumed to be yarns.

The tension meters described in the aforesaid patents employ three members which engage the yarns and which are disposed generally along a reference line. In operation, the yarns are disposed generally along that reference line passing over one side of the two end yarn engaging members and over the other side of the center member. During the tension measuring operation, the filaments are deflected from a straight path as it passes over the center member. Tension on the filament creates a force tending to move the center member in such a direction as to straighten the filament path. The center member is connected, via a tensioned linkage, to a pointer which travels over a calibrated indicator dial. The movement of the center member is proportional to the tension in the filament, and this motion is transmitted to the pointer so that the tension can be read directly on the calibrated dial.

One major use of such tension meters has been the measurement of yarn tension in a "shed" of yarns on a loom. Typically, the loom operation is interrupted and a fixed number of adjacent yarns inserted into a tension meter. This is an undesirable measurement scheme, however. Not only is the loom "down time" undesirable, but the "running tension" of the yarns can vary substantially from the stationary measurement. The alternative of measurement as the loom is running results in inaccurate and non-reproducible readings due both to the dial vibrations from short-term yarn tension fluctuations and to the difficulty of engaging the same number of yarns in each measurement.

SUMMARY OF THE INVENTION

A principal object of the present invention is to provide a tension meter of the general type described above which will have improved stability, accuracy, and reproducibility of the tension measurement despite use with filaments moving at high speeds or use in vibratory environments such as on-the-loom tension measurements during loom operation or to get practical averages for fluctuating tensions. Other objects are to provide a stable and accurate device which is rugged in construction, easy to use, and adaptable for use over a wide range of operating conditions.

In one aspect the invention features a tension meter including a pair of spaced filament engaging members fixed with respect to each other and each having a filament engaging surface. A third filament engaging member is movably mounted on a base and disposed between the pair, the third member being movable in a plane perpendicular to a reference line tangent to the aforementioned surfaces of the pair. The three members are adapted to engage one or more filaments with the pair of members and the third member, respectively, disposed on opposite sides of the filament. First biasing means are provided to cause the third member to deflect, from a straight path, filaments engaged by the members. Means are also provided, connected to the third member, for indicating the magnitude of its motion. Damping means are provided to damp vibrations of the third member and comprise a cylinder, a piston disposed within the cylinder for sliding motion, means connecting the piston to the third member, and an adjustable valve in the cylinder for achieving critical damping.

Preferably the connecting means comprises a member attached to the third filament engaging member and including a portion spaced apart from that member whereby such portion undergoes movement proportional to, but greater than, the motion of the third member; the pair of spaced filament engaging members are mounted upon a support which is movably mounted on the base for movement between first and second positions. The filament engaging members are preferably shaped in such a manner that, upon opening the inserting mechanism, it is possible not only to engage individual filaments and strips the tension of which is to be measured but particularly to grab a uniform width of a multiplicity of filaments such as is required, for instance, to grab a significantly reproducible number of filaments in the warp beam of a textile or wire loom. It is also preferred that the filament engaging surface of the third member be on one side of the above-mentioned reference line when the support is in the first position and on the other side of that reference line when the support is in the second position; that the meter include second biasing means biasing the support towards the first position; that the third filament engaging member be bent so as to facilitate inserting the tension meter into a mulitplicity of yarns and to hold them securely against a curved support surface adjacent the filament engaging members in test position despite the pulsating motion of the loom; and that the adjustable valve comprise an opening in the cylinder, barrier means mounted for movement with respect to that opening, and means for moving the barrier to alter the portion of the opening effectively masked by the barrier.

In another aspect the invention features improvements in tension meters which comprise a base, first and second filament engaging members fixed with respect to each other, and a third filament engaging member movably mounted on the base between the other pair of members. The improvements comprise features which singly and cooperatively provide for a tension meter which is useable on moving yarns of loom yarn shed. The features assure both accurate insertion of the meter into the shed and lack of damage to the moving yarns. Among the former features are the provision of structure giving at least one of first and second filament engaging members a substantial thickness in a direction substantially perpendicular to a reference line tangent to the filament engaging portions of those members, whereby insertion of that thick member in a shed of yarns separates a pair of adjacent yarns to permit insertion of the other member between the same pair of yarns. Preferably both of the first and second members in such structure which comprise a convex arcuate surface spaced apart from a concave arcuate surface which forms the filament engaging portion of the member. The convex surface, of course, assists in maintaining the running yarns free of damage. Other features which contribute to this end include a support for the first and second members having a convexly curved surface from which those members project and connecting means (for damping means as described above) which comprise a portion extending tangentially from that convexly curved surface.

DETAILED DESCRIPTION OF THE DRAWINGS

Other objects, features, and advantages of the invention will appear from the following description of a preferred embodiment, referring to the accompanying drawings, in which:

FIG. 1 is a perspective view of a tension meter constructed according to the invention;

FIGS. 2 and 3 are partially broken away side elevations of opposite sides of the tension meter of FIG. 1; and

FIG. 4 is a view taken at 4--4 of FIG. 2.

DESCRIPTION OF A PREFERRED EMBODIMENT

The tension meter of the invention includes a base member 10. Plastic panels 12, secured to base 10 provide a grip or handle portion 13. A pair of filament engaging members 14, 16 are mounted upon a support 18 and project from the curved front surface 20 thereof. As best seen in FIG. 2, the support 18 is pivotally mounted on the base 10 for rotation about axis 22. The support 18 includes a first projection in the form of a "trigger" 24 and a second projection 26 which engages a biasing spring 28 mounted on base 10 within the handle 13. The spring 28 biases the support 18 toward a first position in which surface 30 of the support engages a stop portion 32 of the base 10. A stop 23 on base 10 defines a second position in the rotation of support 18 (i.e., the clockwise limit of rotation as viewed in FIG. 2). The filament engaging members 14, 16 include arcuate filament engaging surfaces 34, 36 respectively. Arcuate outer surfaces 35, 37 are also provided with each of the members 14, 16 having a substantial thickness between its pair of arcuate surfaces (e.g., about 1/2 inch).

A center filament engaging member or "sensing member" 38, having curved filament engaging surface 40, is disposed midway between members 14 and 16. The curvature is in the opposite direction from that of surfaces 34, 36. The member 38 also has a smoothly rounded end which serves, along with the smooth curvature, to prevent damage to yarns, especially during on-the-loom tension measurements.

The member 38 is mounted on an arm 42 which is pivotally mounted at 44 upon the base 10. The arm 42 extends away from the member 38 beyond the location of pivot 44. An arcuate rack gear 46 (see FIG. 2) is mounted on the end of arm 42 remote from member 38. Rack gear 46 engages gears 48 affixed to shaft 50 which projects from the rear of an indicator device 52 of conventional design. The arm 42 is biased in an opposite rotational sense as support 18 by means of spring member 54 which is mounted upon the base 10 and which bears upon projection 55 of arm 42. As best seen in FIG. 3, a stop surface 56 of the base 10 defines the "rest" position of arm 42 under the influence of the spring 54. A sheet metal connector member 58 is affixed to the arm 42 and includes a portion 60 which is further from the pivot 44 than is member 38. Member 58 is secured to arm 42 at two spaced apart locations 59, 61 to prevent "sway" or deflection of member 58 out of the plane of motion of member 38 (i.e., a plane perpendicular to reference line X of FIG. 1).

As best seen in FIG. 4, a damping device, indicated generally at 62, is provided for the purpose of enabling the operator to operate the device in a unique manner by adjusting it to achieve critical damping for steady readings in vibratory environments, such as looms. The damping device for making this unique result possible comprises a cylinder 64 which is mounted upon a support 66, itself affixed to the base 10. A piston 68 is disposed within cylinder 64 for sliding motion and maintaining a substantially air-tight fit within the cylinder. A connector rod 70 is disposed between piston 68 and a fitting 72 mounted upon portion 60 of connector member 58. The rod 70 is connected to both piston 68 and fitting 72 with a universal-type joint 74, 76.

The end plate 78 of cylinder 64 includes a tapered central opening 80. A barrier member 82 having a matching taper is axially aligned with the opening 80 and comprises the end of a shaft 84 which is treaded in a support 86 mounted upon end plate 78. A wheel 88 is affixed to the protruding end of shaft 84. The wheel 88 may include indicia 90 around its circumference which serve to indicate the rotational orientation of the wheel with respect, for example, to the fixed support 66. An overdrive in the form of plastic ring 89 is built into connection between dial 90 and shaft 84 so that the sensitive threads of screw 82 cannot be damaged due to excessive twisting of them.

In opertion, the tension meter is held in the hand as shown in FIG. 1 and the trigger 24 depressed against the influence of spring 28 to rotate the filament engaging members 14 and 16 from a first or "rest" position (indicated in FIG. 1 by reference line X drawn tangent to filament engaging surfaces 34, 36) to a second position (indicated by reference Y) defined by stop 23 (FIG. 2). As is evident from FIG. 1 this precise, reproducible movement of members 14, 16 sufficiently separates their filament engaging surfaces from the filament engaging surface 40 of the central member 38 so that several filaments (e.g., yarns 92) may be conveniently engaged so as to pass over surfaces 34, 36 and under surface 40. Upon release of trigger 24 the support 18 and members 14, 16 will return to their original position with respect to the base 10. Upon release, the yarns slide automatically into concave surfaces 36 and 34. If the yarns 92 now engaged by members 14, 16, and 38 are under tension, they will resist assuming the serpentine path which would be required by the initial positions of those members. By choosing a spring 28 which exerts more force than the spring 54, this resistance of the filament will cause movement of member 38, against the influence of spring 54, rather than movement of the members 14, 16. The resulting small angle rotational movement of member 38 and arm 42 about the pivot 44 causes rack gear 46 to rotate gear train 48. The indicator dial 52 includes a pointer to which a spiral take-up spring is connected (not shown) which moves in response to the rotation of shaft 50, in a conventional fashion, and calibrated indicia relating the position of the pointer to the tension in the filament which caused motion of the pointer.

When tension meters are attempted to be used on running yarns of yarn shed, machinery vibration transmitted to the filaments causes rapid, short term fluctuations in the tension of the filaments and resultant overshooting due to the inertia of the movement and bouncing of the pointer in the indicator mechanism 52 thus making an accurate determination of tension in the filament virtually impossible. This is alleviated by the damping device 62. Any motion of the member 38 is transmitted through connector member 58 and rod 70 to piston 68 within cylinder 64 of the damping mechanism 62. With a substantially air-tight fit of the piston 68 within the cylinder 64, the high or low pressure conditions which would obtain within the cylinder attendant forward and backward motion of piston 68 within the cylinder, respectively, are alleviated only by the friction caused by the passage of air (from the interior of cylinder 64 to the ambient, or vice versa) through the adjustable orifice (in cylinder end plate 78) comprising opening 80 and barrier member 82. By rotation of wheel 88 to adjust the position of barrier 82 with respect to the opening 80 the friction attendant air passage from the interior to the exterior of the cylinder 64 (and vice versa) can be adjusted with effectively infinitely fine variations. The adjustment of air friction, of course, determines the amount of resistance to sliding motion within the cylinder 64 which the piston 68 experiences. Such resistance to motion of piston 68 can be adjusted to act as a critical damping force on the member 38 through connecting rod 70 and connector member 58. With the proper positioning of the barrier 82 (easily determinable by simple slow rotation of wheel 88 until the pointer of indicator 52 has a minimum of jittering yet adequate response), the piston 68 will assume a location within the cylinder 64, as influenced by the motion of member 38 in response to tension in the filaments engaged between members 14, 16, and 38. Since the "base level" of tension in the filaments is substantially unchanging, the force exerted upon member 38 and ultimately piston 68 will be substantially constant in time thus permitting time for air to escape through opening 80 so that the resistance to motion of piston 68 is overcome and member 38 may assume a position which reflects the true tension in the filaments. The time required for this to occur, while being merely seconds or less, is very long compared to the duration of the individual fluctuations which cause the difficulty in reading the indicator 52. (Loom motions may usually be in excess of 200 picks per minute.) These very rapid fluctuations in tension attempt to cause member 38 to deviate from the proper position which would reflect the practical averages of tension in the filaments. Any such deviations, of course, would cause motion of piston 68 in cylinder 64 and is thus resisted. With the proper positioning of the barrier 82 and the opening 80 to achieve active damping, as discussed above, there is insufficient time during the duration of any given fluctuation for sufficient air to pass through the opening 80 to permit the degree of motion of piston 68 which would occur absent the aforementioned resistance of the piston to such motion. Thus, the motion of piston 68 and the attendant deviation of member 38 in response to rapid fluctuations in tension is at most a fraction what it would be in absence of the effect of the damping device 62.

It has been discovered that with damping means as described above provided in a tension meter as described, critical damping may easily be achieved. I.e., a reduction in indicator fluctuations occurs at a particular, empirically determined setting of wheel 88 for almost any tension measurement situation.

In the preferred form of the device as illustrated in the accompanying drawings, the damping device 62 receives an exaggerated version of the vibration transmitted to the member 34 because of the length of the lever arm 58 (i.e., the connection of rod 70 to a remote portion 60 of the member 58). Since the portion 60 is much farther removed from the center of rotation 44 than is the member 38, this magnification of motions of the member 38 occurs automatically. This effect, of course, increases the efficiency of member 62 to effectively damp the undesired motions of the member 38, as will be understood by those skilled in the art. Of course, perfectly adequate damping may be achieved without this particular feature which magnifies the vibratory motion of the sensing member 38.

The features discussed above provide for a tension meter which is suitable for use in vibratory environments. Such environments, of course, include the measurement of tension in the yarns of a yarn shed on a running loom. There are further problems in the measurement of tension in that particular situation, however, which are overcome by other features of the present invention. As is well known, such a shed comprises a large number (e.g., thousands) of generally parallel yarns lying in a plane with each yarn running across that reference plane. In a tension measurement typically a number (e.g., 20) of yarns are engaged by the tension meter for a single measurement. Thus one important requirement for a tension meter is that a substantially reproducible number of yarns be engaged by the meter each time a tension reading is desired. Furthermore, it is important that each of the outer filament engaging members (i.e., members 14, 16 of FIG. 1) be inserted between the same pair of adjacent running yarns. This latter requirement is achieved in the present invention by providing the members 14 and 16 with a substantial thickness in a direction perpendicular to the direction of yarn travel so that insertion of one of those members separates the relevant adjacent yarns making insertion of the other of those members at the appropriate place a simple matter. Furthermore, the concave curvature of surfaces 34 and 36 retain the yarns being sampled in a fixed orientation with respect to the remaining components of the tension meter so that an accurate reading can be achieved, while convex surfaces 35, 37 assure that adjacent yarns will not be damaged as they travel at high speed past the tension meter. The convex curvature of the surface 20, also adjacent the running yarns achieves this same result. The tangential projection of the member 58 from the curved surface 20 removes the member 58 and the damping device 62 from the vicinity of the plane of the yarn shed and thus prevents damage to the yarn by inadvertent contact of the running yarns with such structure.

Finally, the provision of a sensing member 38 in the form of a bent elongated member having a smoothly rounded end assures the damage-free insertion of that member into the yarn shed and the retention of the yarns being sampled in an appropriate position for accurate measurements.

From the foregoing, it will be appreciated that the various features of a tension meter constructed according to the present invention singly and cooperatively provide for a device which is suitable for use in vibratory environments in general, and, most importantly, for measurements of tension in the yarns of a yarn shed on a running loom.

Naturally, the novel features discussed herein have applicability beyond trigger tension meters. For example, such features may be easily incorporated into tension meters such as shown in my previous U.S. Pat. Nos. 3,177,708; 3,344,664; and 3,398,575.

While a particular preferred embodiment of the invention has been illustrated and described in detail, other embodiments are within the scope of the invention as defined in the claims.