US3089657A - Yarn traversing apparatus - Google Patents

Description

May 14, 1963 P. J. CHAUSSY YARN TRAVERSING APPARATUS 2 Sheets-Sheet 1 Filed Jan. 5, 1961 FIG.

FIG?) May 14, 1963 Filed Jan. 5, 1961 P.- J. CHAUSSY YARN TRAVERSING APPARATUS 2 Sheets-Sheet 2 United States Patent This invention relates generally to the traverse winding of yarn at high speeds and more particularly to improvements in the cam. which is an integral part of the Winding apparatus.

It is well known in the textile field to wind substantially cylindrical packages of yarn, thread or the like on a bobbin in a traverse winding apparatus. In such an apparatus the yarn passes through a reciprocating guide to a rotating package. The guide is attached to a follower which rides in a generally helical groove in the surface of a rotatably driven barrel cam and is constrained to follow a reciprocating linear path of travel. An apparatus of this type has been disclosed by Hunter in US. Patent No. 2,689,694. Although such an apparatus is entirely suitable for use at the speeds contemplated, it has been found that higher winding speeds lead to the formation of unstable packages having bulged end faces and overthrown ends. These unacceptable results are caused by the reduction in follower velocity in the circular reversal portion of the cam profile and the concurrent deposit of surplus yarn at the package ends. In the past, it has been thought that a relatively sharp, angular reversal portion in the cam profile would eliminate the buildup of shoulders. Actually, the shoulders still appear. Furthermore, such a remedy is unpracticable because of the high acceleration forces acting on the follower and guide, i.e., the nearly instantaneous change in direction subjects the follower to excessive acceleration and loads.

The principal object of the present invention is to provide cam profile improvements which facilitate the formation at high winding speeds of stable, substantially cylindrical, uniformly dense yarn packages having flat end faces.

A corollary objective is the provision of a cam profile which facilitates high speed winding without subjecting the cam and follower to excessive loads at the cam reversal points.

These and other desirable objectives are accomplished in a Winding apparatus which includes a rotatably driven barrel cam having a continuous, generally helical groove in its surface, a cam follower riding in the groove and guide rails limiting the follower to a reciprocating linear path of travel between the cam reversal points. A suitable yarn guide is attached to the follower for movement therewith. The cam groove is characterized by successive straight, cycloidal, harmonic, cycloidal and straight portions in its profile at the reversal points.

Other objectives will become apparent in the following specification wherein reference is made to the accompanying drawings in which:

FIGURE 1 is a partial elevational view of a traverse winding apparatus into which the improvement of the present invention may be incorporated;

FIG. 2 is a cam profile having harmonic curves at the reversal points;

FIG. 3 illustrates the package outline which results when the cam profile of FIG. 2 is employed;

FIG. 4 illustrates the theoretical Package outline corresponding to the profile of FIG. 2;

FIG. 5 is the cam profile of the present invention;

FIG. 6 shows the actual package formation resulting when the cam profile of FIG. 5 is employed;

FIG. 7 is the theoretical package outline corresponding to the profile of FIG. 5;

FIG. 8 is an enlarged diagram of one of the reversal points shown in the profile of FIG. 5; and

FIG. 9 is a top plan view of a barrel cam having a groove corresponding to the profile of FIGS. 5 and 8.

The winding apparatus chosen for purposes of illustration in FIG. 1 includes as components thereof a rotatably driven barrel cam 10 having a groove 12 in its cylindrical surface and a follower 14 having a yarn guide attached thereto which follower rides in groove 12 and is constrained to a linear path of travel by rails 16, 18.

The magnitude of the acceleration forces imposed on a cam follower is a function of the radius of the reversal curves with the practical minimum radius being limited by the ability of the follower to withstand high inertial forces. It is known that traverse cams with sharp constant velocity reversal patterns subject the follower to instantaneous acceleration shocks. Where the reversal pattern is circular, the shocks are not instantaneous but are nevertheless abrupt.

A cam profile having harmonic reversal curves has been designated with the numeral 20 in FIG. 2. When such a profile is milled into a cam of the type shown in FIG. 1, it produces gradual acceleration changes and is accordingly ideally suited for use in a high speed apparatus. Even with such gradual acceleration changes, there is still a deposit on the package of surplus yarn or shoulders 22 (FIG. 4) opposite the reversal points. The pressing action of a drive rol-l (not shown) which is in frictional contact with the package surface assists in redistributing the yarn from the theoretical outline shown in FIG. 4 to the actual though exaggerated saddle back shape shown r in FIG. 3.

In FIGS. 5 and 8 the preferred cam profile of the present invention is shown and has been designated with the numeral 24. Profile 24 includes straight portions 26, harmonic reversal curves 28, and intermediate cycloidal curve portions 30. In each portion 30, there is a change of cam direction or slope which results in a gradual acceleration of the follower as it leaves a straight portion 26 and a gradual deceleration as it leaves a harmonic curve 28. In the actual reversal portion 28 full advantage is taken of the gradual acceleration characteristics of a harmonic curve as discussed above in connection with FIGS. 2-4. The stroke limit or reversal point for follower 14 is at the mid-point of harmonic curve 28. The overall increase in velocity in the approach to and departure from the reversal point leads to a theoretical cutback 32 (FIG. 7) near the ends of the package. In actual practice, surplus yarn shoulders 22 corresponding to harmonic curves 28 slip into the low density regions or cutbacks 32 corresponding to cycloidal curves 30. The pressing action of the package drive roll assists in this redistribution of yarn. Cutbacks 32 disappear and the package faces are flat, as indicated at 33. Since cutbacks 32 result from an increase in follower velocity in the cycloidal portions 30 of profile 24, portions 30 are also referred to as cutbacks in the profile. The apparatus shown in FIG. 9 has a cam groove 12' corresponding to the profile of FIG. 8 but is otherwise identical to the apparatus of FIG. 1.

Although the cutback portions 30 of the preferred profile are cycloidal, it is practicable and sometimes advantageous to use other curves of varying radius, e.g., polynomials, as the junctures between the straight and harmonic curve portions. The principal requirement is that the acceleration characteristics at both ends of the transitional or cutback curve blend with the acceleration characteristics of the adjacent curves.

As is apparent from the tangent lines shown in FIG.

8, the cutback portions 39 join constant velocity portions 26 and harmonic portion28 atpoints of zero acceleration. Thus, the follower 14 enters a cutback portion 30 at constant velocity, accelerates to some finite value and leaves the cutback portion at zero acceleration. The transition is continuous and smooth with no sudden or large changes in acceleration.

With reference to FIG. 8 it should be noted that the maximum pressure angle 99 for the profile of this invention exceeds the normal pressure angle or cam helix angle 88 by the size of the cutback angle 77. Previous cam profiles have not included a definite cutback angle 77.

Substantially cylindrical packages of heavy industrial yarn have been wound at high speeds using a cam having a cutback angle 77 as large as 13, a helix or normal pressure angle 88 of about 30, and a maximum or total pressure angle 99 of over 40. Similarly, a cutback angle of as little as 4 with a cam helix angle of about 30 is suitable for lighter textile counts. Between these two extremes cutback angles of from 4-13 have been used successfully in the winding of various nylon, polyester, and spandex fiber counts at windup rates approaching 5,000 yards per minute.

Although the preceding description relates primarily to the use of barrel cams, it is apparent that the concept of adding a cutback portion to a cam profile is equally applicable to plate and other type cams. Additional changes to and adaptations of the disclosed cam profile may be made without departing from the spirit of the present invention which is accordingly intended to be limited only by the scope of the appended claims.

I claim:

1. A winding apparatus including a rotatably driven barrel cam having a continuous generally helical groove in its surface, a cam follower riding in said groove and means limiting the follower to a reciprocating linear path of travel between the cam reversal points, said follower having a guide fixedly attached thereto and said groove having a profile including successive straight, cutback curve, reversal curve, cutback curve and straight portions, said profile being entirely curvilinear in the portions interconnecting said straight portions, said cutback curves being respectively curves of gradual acceleration and deceleration, each reversal curve having gradual deceleration and acceleration characteristics respectively in the approach to and departure from said reversal points.

2. The apparatus of claim 1 wherein said cutback curve portions are cycloidal.

3. The apparatus of claim 1 wherein the cutback angle is at least 4.

4. The apparatus of claim 1 wherein the maximum pressure angle is in excess of 30 and the cutback angle is at least 4.

References Cited in the file of this patent UNITED STATES PATENTS 1,357,434 Anderson Nov. 2, 1920 2,858,993 Siegenthaler Nov. 4, 1958 2,934,284 Steeger Apr. 26, 1960 2,959,967 Metzuer Nov. 15, 1960 FOREIGN PATENTS 1,054,337 France Oct. 7, 1953

Claims (1)

1. A WINDING APPARATUS INCLUDING A ROTATABLY DRIVEN BARREL CAM HAVING A CONTINUOUS GENERALLY HELICAL GROOVE IN ITS SURFACE, A CAM FOLLOWER RIDING IN SAID GROOVE AND MEANS LIMITING THE FOLLOWER TO A RECIPROCATING LINEAR PATH OF TRAVEL BETWEEN THE CAM REVERSAL POINTS, SAID FOLLOWER HAVING A GUIDE FIXEDLY ATTACHED THERETO AND SAID GROOVE HAVING A PROFILE INCLUDING SUCCESSIVE STRAIGHT, CUTBACK CURVE, REVERSAL CURVE, CUTBACK CURVE AND STRAIGHT PORTIONS, SAID PROFILE BEING ENTIRELY CURVILINEAR IN THE PORTIONS INTERCONNECTING SAID STRAIGHT PORTIONS, SAID CUTBACK CURVES BEING RESPECTIVELY CURVES OF GRADUAL ACCELERATION AND DECELERATION, EACH REVERSAL CURVE HAVING GRADUAL DECELERATION AND ACCELERATION CHARACTERISTICS RESPECTIVELY IN THE APPROACH TO AND DEPARTURE FROM SAID REVERSAL POINTS.

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