US3861608A

US3861608A - Traversing mechanism

Info

Publication number: US3861608A
Application number: US410679A
Authority: US
Inventors: John Gilbert Mohr; James William Hartman; David Michael Arno
Original assignee: Johns Manville
Current assignee: Johns Manville Corp; Johns Manville
Priority date: 1973-10-29
Filing date: 1973-10-29
Publication date: 1975-01-21
Anticipated expiration: 1992-01-21
Also published as: IT1021848B; BE821120A; JPS5140176B2; JPS5071945A

Abstract

An apparatus for winding continuous strands of material about rotating cores to form strand packages is provided with primary traversing mechanisms which impart a primary traversing motion to the strands as they are being wound on the packages whereby the strands progress and regress to define a series of bights. A secondary traversing mechanism is provided to impart a secondary traversing motion of the strands relative to the packages to advance the series of bights back and forth across the peripheral face of the packages. The primary traversing mechanisms each comprise a first series and a second series of cam members having outwardly facing convex surfaces for engaging the strands. The convex surfaces of the cam members of the first and second series face in opposing directions with the convex surfaces for successive cam members of each series being progressively displaced relative to preceding cam members in a direction parallel to the axis of rotation of the traversing mechanism. With this construction the first series of cam members move the strands in one direction and the second series of cam members move the strands in an opposite direction.

Description

ilnited States Patent Mohr et al. .1 Jan. 21, 1975 TRAVERSING MECHANISM Primary ExaminerStanley N. Gilreath [75] Inventors: John Gilbert Mohr, Maumee; James Attorney 4 Firm Robert Krone;

William Hartman; David Michael John Llster Arno, both of Toledo, all of Ohio [73] Assignee: Johns-Manville Corporation, ABSTRACT Greenwood Village Arapahoe An apparatus for winding continuous strands of matecounty Colo rial about rotating cores to form strand packages. is 22 Filed; (y 29 973 provided with primary traversing mechanisms which impart a primary traversing motion to the strands as [21] Appl- (L679 they are being wound on the packages whereby the strands progress and regress to define a series of [52 US. Cl. 242/43, 242/18 G g A secondary traversing mechanism iS Provided 51 im. c1 36511 54/28 to impart a Secondary traversing motion of the strands 5 Field f Search 242/43 432 13 G, 1 R relative to the packages to advance the series of bights back and forth across the peripheral face of the packages. The primary traversing mechanisms each com- [56] References Cited firise a first serjjefs a second serie; of ezfim members avmg outwar y acmg convex sur aces or engaging UNITED STATES PATENTS the strands. The convex surfaces of the cam members 2,391,870 1/1946 Beach 242/43 of the first and Second Series face in Opposing (limo a g tions with the convex surfaces for successive cam 3 056 711 lO/1962 III 242/1B G mfinlbers of each.series being Progressive/Y displaced 3:292:872 12/l966 Haydenw H 242/43 relatlve to precedmg cam members in a d1r ect1on par- 3356304 12,1967 GenSonW 242/43 X allel to the ax1s of rotat1on of the traversing mecha- 3,399,841 9/1968 Genson.... 242/43 nism- With this Construction the first Series of Cum 3,414,956 12/1968 Genson 242/18 G X members move the strands in one direction and the 3,695,523 10/1972 Genson et a1... 242/43 X second series of cam members move the strands in an 3,784,121 l/l974 Arno Ct al 242/43 pposite direction I 11 Claims, 8 Drawing Figures TRAVERSING MECHANISM BACKGROUND OF THE INVENTION The present invention is related to traversing mechanisms and particularly to improved traversing mechanisms which effect a primary traversing movement of a plurality of strands while maintaining the strands separated for the major part of the traversing movement without destroying the integrity of the strands.

While other applications for the traversing mechanisms of the present invention may be found, the traversing mechanisms of the present invention are primarily intended for use in the manufacture of continuous glass strands. In this instance, a plurality of continuous glass strands are drawn from a bushing and are wound onto packages. The packages produced in this operation are intended for use as sprayup gun rovings.

Thus, these packages must be void of loops, gobs and snarls so that the roving will readily unwind from a package and pass through the chopping operations required in a sprayup gun roving operation.

Attempts to use a primary traversing mechanism comprising a plurality of elongate straight elements which are supported in spaced-apart parallel relationship to define a cylindrical pattern with the elements extending at an oblique angle relative to the axis of rotation of the traversing mechanism (e.g. a birdcage traverse) for producing packages suitable for sprayup gun roving operations have been unsuccessful. Such traversing mechanisms are suitable for forming packages used for other purposes but for sprayup gun roving operations they cause too wide a splitting of the strands at their point of entry into the package, e.g. about a half inch. Even though the birdcage type of traverse produces a package suitable for some chopping operations and maintains the integrity of the strands wound onto the package, the wide splitting caused by this type of traverse causes loops, gobs and snarls which are evident in the ends of the roving packages. These loops, gobs and snarls interfere with proper passage of the roving through guide eyes of a sprayup gun and cause breakouts and clogging when the roving passes through motor driven chopper portions of such guns. Thus the package formed is unacceptable for use in sprayup gun roving applications.

Prior art traverses include traverses illustrated in US. Pat. Nos. to Hayden et al., No. 3,040,999 issued June 26, 1962; Hayden No. 3,292,872 issued Dec. 20, 1966; Frickert No. 3,056,771 issued Oct. 2, 1962; Genson No. 3,399,841 issued Sept. 3, 1968, and Genson No. 3,414,956 issued Dec. 10, 1968. The Hayden patents work well with a single strand but cause too great a split when used on a plurality of strands, thereby causing problems similar to those experienced with the birdcage traverse. The Frickert patent illustrates a traverse with a pair of spirally shaped complementary cam members for forming split strands which are brought together at spaced intervals. The first Genson patent relates to a barrel type traverse which is somewhat similar to the birdcage traverse mentioned above. The second Genson patent relates to a traverse with a pair of straight cam members for traversing split strands with a comb being used to help maintain the strands in a split relationship.

It is an object of the present invention to provide a traverse which, for the most part, maintains the strands in a split relationship but which brings the strands together at spaced intervals to form a package suitable for sprayup gun roving operations. The spread preferably does not exceed about a quarter inch at the point of entry of the strands to the forming package. It is a further object to provide a traversing mechanism which does not destroy the integrity of the strands so that the strands do not break up during the sprayup gun roving operation into the individual filaments making up the strands.

Accordingly, the present invention comprises a traversing mechanism having a first series of cam members and a second series of cam members which are mounted for rotation about the axis of rotation of the traversing mechanism. Each of the cam members has an outwardly facing convex surface for engaging the strands and for maintaining the strands in a split relationship except at spaced intervals when the strands are momentarily brought together. The convex surfaces for the first'series of cams face in a direction opposing the convex surfaces of the second series of cams. The convex surfaces for the successive cam members of each of said series are progressively displaced relative to preceding cam members in a direction parallel to the axis of rotation of the traversing mechanism whereby the first series of cam members move the strands in one direction and the second series of cams move the strands in the opposite direction. Preferably all of the convex surfaces have the same radius of curvature and the convex surfaces are spaced radially outward from the axis of rotation of the traversing mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation of an apparatus for forming a plurality of multi-filament glass strands and for winding the plurality of strands into packages;

FIG. 2 is an end elevation of the apparatus of FIG. 1 as viewed from the right of FIG. 1;

FIG. 3 is a perspective view of a first traversing mechanism of the present invention;

FIG. 4 illustrates one of the two sets of cam members of the traversing mechanism of FIG. 3;

FIG. 5 is a perspective view of a second traversing mechanism of the present invention;

FIG. 6 illustrates one of the two sets of cam members of the traversing mechanism of FIG. 5.

FIg. 7 is a perspective view of a third traversing mechanism of the present invention; and

FIG. 8 illustrates one of the two sets of cam members for the traversing mechanism of FIg. 7.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS FIGS. 1 and 2 illustrate a pair of traversing mechanisms 20 of the present invention which are utilized in an apparatus 22 for forming a plurality of multifilament continuous glass strands. The apparatus 22 includes a glass-melting receptacle or bushing 24 from which a plurality of filaments 26, e.g. 1,600 filaments, are drawn by rotating cores 28 that are mounted on a rotating mandrel 30 which is driven by a motor 32. The filaments 26 are gathered into a plurality of strands 34, e.g. eight ZOO-filament strands, by converging rollers 36. The strands are then wound onto the rotating cores 28 to form packages 38. Binders and the like are applied to the filaments 26 as they are being drawn together to form the strands 34 by a conventional binder applicator 40.

There are two traversing assemblies. The traversing mechanisms are the primary traversing assembly and the traversing assembly 42 is the secondary traversing assembly. The secondary traversing assembly 42 includes a double-acting hydraulic piston and cylinder assembly 44 which reciprocates the packages 38 back and forth relative to the traversing mechanisms 20 by moving the mandrel support 46. The packages 38 are each carried on the mandrel so that the centers of the packages 38 lie in vertical planes which are centered relative to the series of strands 34 being wound onto the particular package when the package is midway along its traversing path. The length of the reciproeating movement of the secondary traverse is regulated to form the packages 38 to the desired width.

The traversing mechanisms 20 of the primary traversing assembly effect a series of progressive and regressive bights of the strands. The series of bights is effected to deter the formation of a parallel lay of adjacent windings. Thus, the primary traverse effects a series of rapidly formed progressive and regressive bights of small amplitude while the secondary traverse effects a relatively slow progression of these bights across the package being formed to helically wrap the series of bights back and forth across the entire width of the package. While the secondary traversing motion is generally effected by moving the mandrel 30 relative to the traversing mechanisms 20 which are held stationary, it will be understood that the secondary traversing action can be effected by holding the mandrel 30 stationary and moving the primary traverses 20 in an axial direction relative to the mandrel 30.

As best shown in FIG. I and 2, the traversing mechanisms 20 are rotated by a motor 48 and are rotatably mounted on pivotal mounting brackets 50. The brackets 50 are pivoted about an axis 52 by a mechanism 54 such as that illustrated in U.S. Pat. No. 3,695,523 issued oct. 3, 1972, to Samual R. Genson et al. The primary traversing mechanisms 20 are moved away from the winding axis of the packages 38 as the packages build up in diameter to maintain the traversing mechanism a desired distance away from the peripheral surfaces of the packages being formed. While FIGS. 1 and 2 illustrate an assembly wherein the primary traversing mechanisms 20 are moved away from the packages 38, means can also be provided to move the packages 38 away from the traversing mechanisms.

FIGS. 3 and 4 illustrate the first traversing mechanism 20 of the present invention which includes a plurality of elongated cylindrical rods or wires forming cam members which are mounted at each end in collars 62. The rods 60 extend parallel with respect to each other and lie in planes which contain the axis of rotation 64 of the traverse mechanism. The rods 60 are spaced 45 from adjacent rods with the ends of the rods 60 being received within apertures of the collars 62. The rods are secured to the collars by set screw 66, similar fastening devices, or by brazing.

There are two

sets

68 and 70 of four cam members making up each traversing mechanism. FIG. 4 illustrates one of the sets 68. The other set 70 of cam members comprises four complementary cam members which are the mirror image of the cam members illustrated in FIG. 4. Complementary cam members of the two sets are located 180 apart and lie in the same plane which also includes the axis of rotation 64 of the traversing mechanism.

Since the two sets of cam members are mirror images of each other, only one set of the cam members. set 68, will be discussed in detail to avoid unnecessary repetition. Each cam member 60 includes

end portions

72 and 74 which are mounted in the collars 62. The

end portions

72 and 74 each have

sections

76 and 78 which extend in a radial direction relative to the axis of rotation of the traversing mechanism. In addition to the end portions, each cam member is provided with at least a first intermediate portion 80 which extends generally parallel to the axis of rotation 64 of the traversing mechanism from the generally perpendicular section 76 of end portion 72. Each of the cam members is provided with a convex portion 82 which has an outwardly facing convex surface. With the first cam member of the set, the convex portion 82 extends between and merges with the intermediate section 80 and the perpendicular section 78. At the point where the intermediate portion 80 and the convex portion 82 merge. there is an outwardly facing concave portion (e.g. with a radius of curvature of about an inch) to assure a smooth transition between these portions. For the second, third and fourth cam members of the set, the convex portion 82 merges with a second intermediate portion 84 located intermediate the convex portion 82 and the perpendicular portion 78. Intermediate portion 84 also extends in a generally parallel direction relative to the axis of rotation of the traversing mechanism.

In the preferred embodiment of the traversing mechanism of FIGS. 3 and 4 the radius of curvature of the convex portion 82 of each cam member is approximately 5 inches with the traverse mechanism having a maximum diameter of about 4% t 1 inches (4-96 inches is preferred) where the convex portion 84 merges with the section 78 or the intermediate portion 84 and a minimum diameter of about 3 i 1 inches (3 inches preferred) for portions 80 which hold the strands out from the axis of rotation of the traverse to prevent the split between the strands from becoming too great. The entire cam member is about 6 inches long with the convex portion 82 for each successive cam member of a set being offset in a direction parallel to the axis of rotation of the traversing mechanism about an inch relative to the convex portion of the preceding cam member.

With this traversing mechanism a contact between the strands and the convex surfaces of the cam members maintains the strands in their split or open relative positions while the strands are being moved side-ways by the action of the second. third and fourth cam members of each set. When the strands come into contact with the first cam member of one of the sets, the strands are momentarily pressed together as the cam member changes or reverses the direction of travel of the strands. The strands then split or open up again and remain split as they pass over the convex surfaces of the second, third and fourth cam members of the particular set. This cycle continues and the mechanism produces a split strand that is rovable and suitable for use in sprayup gun roving operations. The mechanism repetitively forces the four strands together for an actual distance along the strands of 6 to 12 inches and successively permits them to be apart for a distance of 4 to 8 feet with the split for four strands being less than a quarter inch between the outermost strands at the point of entry into the forming package. With this degree of split, loops, gobs and snarls are eliminated and the roving is easily unwound from the package thus formed and passed through a sprayup gun. 7

FIGS. 5 and 6 illustrate a second traversing mechanism 90 of the present invention. Like the first traverse mechanism 20, this traverse mechanism is mounted as shown in FIG. 1 and 2 and is made up of two

sets

92 and 94 of cam members 96 with one set of cam members being a mirror image of the other set of cam members. Complementary cam members of the two sets are located 180 apart and lie in the same plane which includes the axis of rotation of the traverse mechanism. Adjacent cam members are spaced relative to each other a distance of 45. The cylindrical rods or wires which form the cam members 96 are mounted at each end in collars 98. The cam members 96 extend parallel with respect to each other with the ends of the rods being received within apertures of the collars 98. The cam members are secured to the collars by set screws 100, similar fastening devices or by brazing. Since one set of cam members is a mirror image of the other set of cam members, only set 92 will be described in detail to avoid unnecessary repetition.

Each cam member 96 includes

end portions

102 and 104. The end portions 102 of the cam members extend generally parallel to the axis of rotation of the traversing mechanism 90 and merge with outwardly facing convex portions 106 of the cam members. The end portions 104 extend generally perpendicular to the axis of rotation of the traversing mechanism. In the first cam member of the set the end portion 104 merges with the convex portion 106. However, for the second, third and fourth cam members of the set the end portions 104 merge with an intermediate portion 108 which extends generally parallel to the axis of rotation of the traversing mechanism between the convex portion 106 and the end portion 104.

Preferably, the cam members 90 are about 4- /2 inches long with the radius of curvature of the convex portion 106 of each member being about 2-5; inches. The maximum diameter of the traverse is about 5 inches and the minimum diameter which corresponds with the diameter of end portions 102 is about l- /z inches. The convex portions of the second, third and fourth cam members are displaced in a direction parallel to the axis of rotation of the traversing mechanism about 96 inch relative to the convex portions of preceding cam members.

With this traversing mechanism, the contact between the strands and the convex surfaces of the cam members maintains the strands in their split or open relative positions while the strands are being moved. sideways by the action of the second, third and fourth cam members of each set. When the strands come into contact with the first cam member of one of the sets, the strands are momentarily pressed together as the cam member changes or reverses the direction of travel of the strands. The strands then split or open up again and remain split as they pass over the convex surfaces of the second, third and fourth cam members of the particular set. While this traverse mechanism functions in a manner quite similar to the first, there are no intermediate portions corresponding to portions 80 of the first traversing mechanism to reduce the difference between the maximum and minimum effective diameters of the strand engaging portions of the traversing mechanism and to hold the strands out from the axis of rotation of the traversing mechanism. Consequently, with this traverse mechanism, some of thevsplit strands ride down the convex surfaces and come too close to the axis of rotation of the traverse mechanism while other strands remain farther out on the convex surfaces causing too great a split. The contact between the strands and the cam members at radial distances from the axis of rotation of the traverse which vary too much cause too great a difference in the length of the strands produced. This results in what is termed a catenary wherein the variation in length between the strands is such that some of the strands tend to form loops in the package.

FIGS. 7 and 8 illustrate the third traversing mechanism 110 of the present invention. Again, the traversing mechanism is made up of two sets, 112 and 114, of four cam members 116 each with one set of cam members being the mirror image of the other set of cam members. Complementary cam members of the two sets are mounted on the traversing mechanism l apart with the cam members lying in a plane which also contains the axis of rotation of the traversing mechanism. Adjacent cam members are spaced 45 apart and extend parallel with respect to each other. The ends of the rods which form the cam members 116 are received within apertures of collars 118. The rods are secured to the collars by set screws 120, similar fastening devices or by brazing.

While the dimensions can vary, typically the cam members are about 6 inches long. Each cam member has a first end portion 122 which extends generally parallel to the axis of rotation of the traversing mechanism and a second end portion 124 which extends generally perpendicular to the axis of rotation of the traversing mechanism. An outwardly facing convex portion 126 of each of the cam elements merges with the end portion 122 and with an intermediate portion 128 which extends generally parallel to the axis of rotation of the traversing mechanism. The intermediate portion 128 extends between and merges with both the convex portion 126 and end portion 124. The convex portion 126 has a radius of curvature of about 5 inches. The maximum diameter of the traversing mechanism is about 2- inches and the minimum diameter of the traversing mechanism is about l- /fi inches. The convex portions are progressively spaced relative to preceding cam members of a set about 13/ 16 of an inch in a direction parallel to the axis of rotation of the traverse mechanism.

With this traverse mechanism the contact between the strands and the convex surfaces of the cam members maintains the strands in their split or open relative positions while the strands are being moved side-ways by the action of the second, third and fourth cam members of each set. When the strands come into contact with the first cam member of one of the sets, the strands are momentarily pressed together as the cam member changes or reverses the direction of travel of the strands. The strands then split or open up again and remain split as they pass over the convex surfaces of the second, third and fourth cam members of the particular set. With this traverse mechanism the strands are split about the same distance as with the first traverse mechanism. However, due to the small diameter of the traverse mechanism, it has tended to give a nonuniform split and a looping problem similar to that associated with the second traverse mechanism is present.

While all of the cam members of the traverse mechanism shown are made with bent wire, the cam members can be made with other equivalent members which would give the same type of point contact between the strands and cam members that the wires provide.

What is claimed is:

1. An apparatus for winding a plurality of continuous strands of flexible material about a core to form a package which apparatus includes a source of said strands, means for rotating said core about a first axis, a traversing mechanism rotatable about a second axis parallel to said first axis and adjacent to a peripheral surface of said package for imparting primary traversing motions to said strands as they are being wound on said package whereby said strands progress and regress to define a series of bights, and means for imparting a secondary traversing motion to the strands relative to the package to advance the series of bights across the peripheral surface of the package, the improvement comprising: said traversing mechanism comprising a first series of cam members and a second series of cam members, mounting means for supporting said cam members in fixed relative positions for rotation about the axis of rotation of said traversing mechanism, each of said cam member lying in a plane containing the axis of rotatioh of rotation of said traversing mechanism, each of said cam members having an outwardly facing convex surface extending in a direction parallel to the axis of rotation of said traversing mechanism for engaging the strands, said convex surfaces of said first series facing in a first direction and said convex surfaces of said second series facing in a second direction opposing said first direction with said convex surfaces for succesisve cam members of said cam members of both of said series being progressively displaced relative to said convex surfaces of preceding cam members of said cam members in a direction parallel to the axis of rotation of said traversing mechanism whereby the first series of cam members move the strands in said first direction and the second series of cam members move said strands in said second direction while maintaining the strands in a split relationship for the major portion of their movement and bringing said strands together at spaced intervals.

2. The improvement as defined in claim 1 wherein: there are four of said cam members in each series with each of said cam membersbeing spaced 45 from adjacent cam members and with said cam members of said first and second series being spaced from said cam members of the other series which are complementary.

3. The improvement as defined in claim 1 wherein each of said convex surfaces of said cam members has substantially the same radius of curvature with said cam members of said first and said second series which are spaced apart 180 being mirror images of each other.

4. The improvement as defined in claim 1 wherein each of said cam members has limiting means adjacent an inner end of said convex surfaces of said cam member for limiting the spacing between said split strands.

5. The improvement as defined in claim 4 wherein said limiting means comprises a second surface of said cam member merging with said convex surface end extending generally parallel with respect to said axis of rotation of said traversing mechanism.

6. The improvement as defined in claim 5 wherein the radius of curvature of said convex surface of each of said cam members is about five inches.

7. The improvement as defined in claim 6 wherein said second surface is spaced radially outward from said axis of rotation of said traversing mechanism with minimum and maximum effective diameters of strand contact surfaces defined by said second surface and said convex surface of said traverse mechanism being about 3 i 1 inches and about 4-% i- 1 inches respectively.

8. The improvement as defined in claim 6 wherein minimum and maximum effective diameters of strand contacting surfaces of second surface and said convex surface are about 2- /2 inches and about l- /fi inches respectively.

9. The improvement as defined in claim 6 wherein maximum and minimum effective diameters of strand contacting surfaces of said second surface and said convex surface differ by about 1 inch to about l-Vz inches.

10. The improvement as defined in claim 1 wherein the radius of curvature for the convex surface of each of said cam members is about 2-% inches.

11. The improvement as defined in claim 1 wherein: said cam members are rods having rounded surfaces for contacting said strands with said cam members contacting said strands at spaced points along said strands. a:

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 861, 608

DATED January 21, 1975 INV ENTOR(S) J. G. Mohr, et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 38 "October" is not capitolized Column 5, line 42 "1-1/2" should read "1-1/4" Column 8, line 15 "end" should read "and" Signed and Sealed this twent zrst a 0 [SEAL] yf D y f 0Cl0b6f1975 A ttes t:

RUTH C. MASON Commissioner oj'Parents and Trademarks

Claims

1. An apparatus for winding a plurality of continuous strands of flexible material about a core to form a package which apparatus includes a source of said strands, means for rotating said core about a first axis, a traversing mechanism rotatable about a second axis parallel to said first axis and adjacent to a peripheral surface of said package for imparting primary traversing motions to said strands as they are being wound on said package whereby said strands progress and regress to define a series of bights, and means for imparting a secondary traversing motion to the strands relative to the package to advance the series of bights across the peripheral surface of the package, the improvement comprising: said traversing mechanism comprising a first series of cam members and a second series of cam members, mounting means for suPporting said cam members in fixed relative positions for rotation about the axis of rotation of said traversing mechanism, each of said cam member lying in a plane containing the axis of rotation of rotation of said traversing mechanism, each of said cam members having an outwardly facing convex surface extending in a direction parallel to the axis of rotation of said traversing mechanism for engaging the strands, said convex surfaces of said first series facing in a first direction and said convex surfaces of said second series facing in a second direction opposing said first direction with said convex surfaces for succesisve cam members of said cam members of both of said series being progressively displaced relative to said convex surfaces of preceding cam members of said cam members in a direction parallel to the axis of rotation of said traversing mechanism whereby the first series of cam members move the strands in said first direction and the second series of cam members move said strands in said second direction while maintaining the strands in a split relationship for the major portion of their movement and bringing said strands together at spaced intervals.

2. The improvement as defined in claim 1 wherein: there are four of said cam members in each series with each of said cam members being spaced 45* from adjacent cam members and with said cam members of said first and second series being spaced 180* from said cam members of the other series which are complementary.

3. The improvement as defined in claim 1 wherein each of said convex surfaces of said cam members has substantially the same radius of curvature with said cam members of said first and said second series which are spaced apart 180* being mirror images of each other.

7. The improvement as defined in claim 6 wherein said second surface is spaced radially outward from said axis of rotation of said traversing mechanism with minimum and maximum effective diameters of strand contact surfaces defined by said second surface and said convex surface of said traverse mechanism being about 3 + or - 1 inches and about 4- 1/2 + or - 1 inches respectively.

8. The improvement as defined in claim 6 wherein minimum and maximum effective diameters of strand contacting surfaces of second surface and said convex surface are about 2- 1/2 inches and about 1- 1/2 inches respectively.

9. The improvement as defined in claim 6 wherein maximum and minimum effective diameters of strand contacting surfaces of said second surface and said convex surface differ by about 1 inch to about 1- 1/2 inches.

10. The improvement as defined in claim 1 wherein the radius of curvature for the convex surface of each of said cam members is about 2- 1/2 inches.

11. The improvement as defined in claim 1 wherein: said cam members are rods having rounded surfaces for contacting said strands with said cam members contacting said strands at spaced points along said strands.