05/104997

05/30/1972

01/08/1971

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Clevepak Corporation (Cleveland, OH)

493/276

156/446, 493/295, 493/304, 156/189

B29D23/20; B31C1/08; B31C1/00; B31B1/62; B31B1/64; B31C1/08

93/36.3,36MM,81,81MT,94A,94PS,59PL 156/189,446

3300355	Method of making irregularly shaped hollow plastic bodies	January 1967	Adams
3328219	Process and device for applying pliable tapes to irregular surfaces	June 1967	Cupery
3580146	METHOD OF MAKING ACCURATELY DIMENSIONED SMOOTH-SURFACED MULTI-LAYER CARDBOARD TUBES	May 1971	Biancamaria

Morse Jr., Wayne A.

I claim

1. In apparatus for forming a sheet into a tubular shape non-circular in cross section: an elongated rotatable mandrel having a non-circular shape in cross section; an elongated rotatable presser roll adapted to be oriented parallel and located adjacent to the mandrel and having a non-circular shape in cross section different from that of said mandrel; the shape of said presser roll being such that, when in surface to surface contact with the mandrel and when rotated at a varying angular velocity that establishes a surface velocity in the area of mutual surface contact equal to that of the mandrel when the mandrel is rotated at a constant speed, the axis of the presser roll will remain essentially stationary.

2. In apparatus for convolutely winding a sheet into a tubular shape non-circular in cross section: an elongated mandrel having a non-circular shape in cross section: means supporting said mandrel for rotation about its central longitudinal axis; means to rotate said mandrel about said axis; an elongated presser roll having a non-circular shape in cross section different from that of said mandrel; means supporting said presser roll for rotation about its longitudinal axis and with its longitudinal axis parallel to and adjacent the axis of said mandrel; the shapes of said mandrel and presser roll being such that the combined distance from said axes to the respective adjacent surfaces of the mandrel and presser roll, in the plane of the two axes, remains constant when both the mandrel and the presser roll are rotated in opposite directions from a predetermined initial relationship at angular velocities that establish essentially equal surface velocities in the plane of the two axes; and means to rotate at least one of said presser roll and mandrel at a varying angular velocity relative to the other to establish essentially equal surface velocities thereof at a line of contact between the presser roll and either the mandrel or a sheet wound onto the mandrel.

3. Apparatus as set forth in claim 2 wherein said presser roll is rotated at a varying angular velocity relative to said mandrel.

4. Apparatus as set forth in claim 2 wherein said last-named means includes a phase changer with an input shaft rotatably driven at a speed proportional to that of said mandrel, a rotatable output shaft for driving the presser roll, and means for varying the speed of said output shaft relative to the input shaft in a predetermined relationship.

5. Apparatus as set forth in claim 4 including means supporting said presser roll for movement toward and away from said mandrel and means yieldably biasing said presser roll toward said mandrel.

6. In apparatus for forming a sheet into a tubular shape non-circular in cross section: an elongated mandrel having a non-circular shape in cross section; means supporting said mandrel for rotation about its central longitudinal axis; means to rotate said mandrel about said axis; an elongated presser roll having a non-circular shape in cross section different from that of said mandrel; means supporting said presser roll for rotation about its longitudinal axis and with its longitudinal axis parallel to the axis of said mandrel; said mandrel and presser roll being shaped so that the radial distance from the axis to the surface of each, considered in the plane of the two axes, varies inversely with respect to that of the other, and the combined distances remain constant, when both the mandrel and the presser roll are rotated in opposite directions and in predetermined timed relationship from a predetermined initial relationship; and means to rotate at least one of said presser roll and mandrel at an increasing angular velocity when said radial distance decreases and at a decreasing angular velocity when said radial distance increases.

7. In apparatus for forming a sheet into a tubular shape non-circular in cross section: an elongated mandrel having a non-circular shape in cross section; means supporting said mandrel for rotation about its central longitudinal axis; means to rotate said mandrel about said axis; an elongated presser roll having a non-circular shape in cross section different from that of said mandrel; means supporting said presser roll for rotation about its longitudinal axis and with its longitudinal axis parallel to the axis of said mandrel; the shapes of said mandrel and presser roll being such that the combined distance from the central longitudinal axes to the respective adjacent surfaces of both, in the plane of the two axes, remains constant when both the mandrel and the presser roll are rotated in opposite directions from a predetermined initial relationship at angular velocities that establish essentially equal surface velocities in the plane of the two axes; means to rotate at least one of said presser roll and mandrel at a varying angular velocity relative to the other to establish essentially equal surface velocities thereof at a line of contact between the presser roll and either the mandrel or a sheet wound onto the mandrel; a vacuum table adjacent said mandrel for supporting a sheet being wound on the mandrel and for retarding movement of the sheet during winding; means for moving a sheet to be wound onto said vacuum table; and means adjacent said vacuum table for applying adhesive to said sheet as the sheet is wound onto said mandrel.

8. In a method of convolutely winding a sheet of paper or the like into a tubular shape of non-circular cross section, the steps comprising: securing an end of a sheet in fixed relationship to an elongated mandrel of non-circular cross sectional shape that is rotatable about its central longitudinal axis, biasing an elongated presser roll that is parallel to the mandrel and rotatable about its longitudinal axis against said sheet as the sheet is wound, said presser roll and mandrel being shaped so that the combined distance from the axes to the adjacent surfaces of both in the plane of the two axes remains constant when both are rotated in opposite directions from a predetermined initial relationship at angular velocities that establish essentially equal surface velocities in the plane of the two axes, rotating said roll and mandrel in opposite directions and at relatively varying angular velocities that continuously establish equal surface velocities of the presser roll and mandrel in the plane of the two axes at the line of contact between the roll and the tube, and maintaining continuous contact between the tube being wound and the presser roll essentially without relative osillation between said two axes.

9. A method as set forth in claim 8 including the step of spraying a quick-setting adhesive on an upwardly facing surface of said sheet as the sheet is wound onto the mandrel.

10. A method as set forth in claim 8 including the step of supporting an unwound portion of the sheet on a vacuum table while the sheet is being wound and tensioning the sheet during winding by decreasing the ambient pressure beneath the sheet.

11. A method as set forth in claim 9 including the step of supporting an unwound portion of the sheet on a vacuum table while the sheet is being wound and tensioning the sheet during winding by decreasing the ambient pressure beneath the sheet.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to convolute winding of tubes non-circular in cross sectional shape.

2. Description of the Prior Art

In the convolute winding of tubes from sheet material it is conventional to press the sheet against the mandrel and previously wound convolutions during winding. Typically, this is accomplished with a follower roll. Where the mandrel is not cylindrical, the follower roll must reciprocate toward and away from the axis of the mandrel during winding to follow the irregular contour of the mandrel and tube. This may be accomplished by merely biasing the follower roll toward the mandrel or by utilizing a cam operated linkage synchronized with the mandrel rotation. While these methods may operate satisfactory at low production rates on non-round sections, the radial inertia forces developed on the follower roll at high winding speeds and high production rates become a limiting factor in obtaining satisfactory roll pressure. This is especially true on shapes very non-circular, such as triangular cross sectional shapes. Where insufficient pressure is exerted against the convolutions during winding, the resulting laminations are not suitably adhered or bonded, and the tube will have low bond strength and a shape that departs from that desired.

SUMMARY OF THE INVENTION

The present invention overcomes the drawbacks suffered when known winding techniques are used in high speed winding operations with irregular shapes. In accordance with this invention a rotatable presser roll is used, of a shape that exerts continuous pressure on the mandrel or windings, but which eliminates the need for the roll to reciprocate toward and away from the mandrel during rotation. To this end, the presser roll is shaped so that when it is driven in an opposite direction from the mandrel in a predetermined timed relationship from a predetermined initial relationship, the combined distances from the center of rotation of each to the line of contact remains constant. The particular contour of the presser roll maintains the combined distances constant when the rotational speeds of the roll and mandrel are unequal to a prescribed extent in a selected timed relationship that establishes equal surface speeds at the pressure line between the mandrel and presser roll. Thus, as the relative radial distances of the roll and mandrel change, from axis to surface, the relative speed of rotation is changed. More specifically, as the radius of the roll decreases relative to that of the mandrel, the relative rotational speed increases in direct proportion to accurately compensate for the inherent decrease in surface speed that would occur at a constant angular velocity. By virtue of the present presser roll construction and drive, not only are inertia forces of the type previously encountered avoided and a constant, substantially uniform, pressure maintained against the convolutions of the sheet, but also any tendency of the presser roll to reduce the winding tension during portions of its contact with the convolutions, due to a difference in surface velocity, is minimized or avoided. As a result, the interply bonding and the ability of the wound tube to retain its shape are substantially enhanced. In addition, separate cover plies, such as labels, which are normally thin and difficult to tension during winding and extremely susceptible to wrinkling, can be smoothly applied to irregular shapes.

In the preferred embodiment, the mandrel and presser roll are each rotated through 360° cycles of equal time duration. The mandrel is driven at a substantially constant angular velocity and the variation in rotational speed between the mandrel and roll during each cycle is established through the presser roll in timed relationship to the rotation of the mandrel. A varying rotational speed of the presser roll is suitably accomplished by driving the roll from the mandrel drive through a phase changer. A differential mechanism that varies the rotational speed of an output shaft relative to that of an input shaft under the control of a cam rotated at a constant angular velocity will suitably accomplish the required continuous phase shifting function. The cam of predetermined shape and driven from the mandrel drive, causes the differential mechanism to change the pressure roll speed in a cyclical fashion coordinated with the variation in the radius of the roll at the pressure line with the mandrel.

Interply bonding and shape retention are further improved by maintaining the sheet under tension as it is wound on the mandrel. This is accomplished in the preferred embodiment of the invention by the use of a vacuum box or table against which the sheet is held by ambient pressure that retards movement of the sheet toward the mandrel during winding.

Additional improvement in the interply bonding and shape retention of the tube is obtained through the use of hot melt or other quick-setting adhesives. The use of such adhesives is made practical in the present invention by substantially reducing the comparatively 1ong time interval between adhesive application and winding that exists in conventional transfer roll or metering bar systems, in which the adhesive is applied to a web prior to the cutting of a sheet to the required length for winding. This time reduction is attained by applying the adhesive uniformly and rapidly to a cut length of sheet material with a spray system or quasi spray system just before or as the sheet is convolutely wound. The quick-setting adhesive results in the immediate development of the interply bond of the convolutely wound tube to materially improve the interply bond strength and shape retention already enhanced by the presser and by the tension under which the sheet is wound.

Accordingly, it is a principal object of this invention to provide an improved method and apparatus for convolutely winding tubes of non-circular cross sectional shape, which permit high production rates and provide improved interply bonding and shape retention. It is a more particular object of this invention to provide an improved winding apparatus in which a presser roll is shaped to maintain continuous contact and pressure against a tube being wound on a mandrel when the roll is rotated at a varying angular velocity relative to the tube and mandrel to establish equal surface velocities of the mandrel and roll at a line of pressure on the sheet or tube between the presser roll and mandrel. It is a further object of this invention to provide a method of convolutely winding a tube and to provide winding apparatus of the type referred to, in which the presser roll is rotated at a varying angular velocity relative to that of the mandrel, that establishes a surface velocity equal to that of the mandrel at the line of pressure on the sheet or tube between the presser roll and mandrel. Other objects, features and advantages of this invention will become apparent from the detailed description that follows, when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of winding apparatus embodying the present invention;

FIG. 2 is a transverse sectional view taken along the line 2--2 in FIG. 1;

FIG. 3 is a sectional view taken along the line 3--3 in FIG. 1;

FIG. 4 is a transverse sectional view taken along the line 4--4 in FIG. 1;

FIG. 5 is a diagram showing the relative angular displacement of the presser roll and mandrel with respect to time;

FIGS. 6 to 9 are diagrams showing a triangular mandrel and a presser roll in four different stages of relative rotation, illustrating the manner in which the parts cooperate and the relative degree of rotation at the different stages shown; and

FIG. 10 is a diagram similar to FIG. 9, illustrating a change in spacing between the mandrel and the presser roll after the winding of a sheet.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Apparatus embodying the present invention, for convolutely winding tubes of non-cylindrical cross sectional shape from a sheet of material, such as paper, is shown illustratively in FIGS. 1 to 4. The basic apparatus comprises a supporting structure 10, a winding mandrel 12, a presser roll 14, a vacuum table 16, and a spray or quasi-spray adhesive applicator 17. The winding mandrel, presser roll, vacuum table and adhesive applicator are supported by the structure 10. The winding mandrel 12 is an elongated member, rotatably driven about its longitudinal axis, for convolutely winding a sheet S of paper or the like into a tube that corresponds in shape to the cross sectional shape of the mandrel. The presser roll is an elongated roll supported parallel to and adjacent the winding mandrel, for applying pressure to convolutions of the sheet S, as the sheet is wound. The cross sectional shape of the roll eliminates the need for it to reciprocate relative to the mandrel during the winding of a sheet. The vacuum table 16 serves as a support for the sheet S prior to winding, and causes the sheet to be tensioned during the winding. The adhesive applicator 17 is an elongated dispenser that sprays or deposits a thin, substantially uniform, coating of quick-setting adhesive on the upwardfacing surface of the sheet S as or just before it is wound onto the mandrel. Any suitable dispenser of this type may be used. As shown in FIG. 1, the applicator 17 extends across the width of the sheet S just ahead of the mandrel 12, transverse to the direction in which the sheet travels during winding. The applicator is supported for adjustment along the direction the sheet moves during winding to vary its position relative to the mandrel. This adjustment assures that the applicator can be accurately positioned so that adhesive is applied only to portions of the sheet that form convolutions subsequent to the first, which is in direct contact with the mandrel.

Typically, when a sheet is to be wound into a tube, it is cut to length from a roll and one end of the sheet is placed into a slot of the mandrel 12 and securely gripped while the body of the sheet is supported on the vacuum table 16. The mandrel is then rotated to wind the sheet about the mandrel and a suitable quick-setting adhesive is applied to the upper surface of the sheet, except for the area that will form the first convolution. The movement of the sheet toward the mandrel during winding is retarded by the ambient pressure on the sheet, due to the pressure differential created by the vacuum table. Each convolution of the sheet is pressed against the mandrel 12 or preceding convolution by the pressure roll 14, to adhere each convolution to the next and to be certain that the convolutions follow the contour of the mandrel.

In the particular embodiment shown, the winding mandrel 12 is triangular in cross section, with rounded corners. In this preferred embodiment, the cross sectional shape of the mandrel is a right-isosceles triangle having two sides 18a, 18b of equal length and a hypotenuse 18c. The sides 18a, b, c are joined by rounded corner portions 19a, b, c. A longitudinal slot 21 extends along the length of the mandrel, in the side 18a, and inwardly toward the central axis of the mandrel, which is indicated at A. The slot 21 is adapted to receive an end of the sheet S. The mandrel is provided with a clamping jaw 22 that is spring biased to a closed or clamping position and which is automatically closed and opened at the beginning and end of each winding cycle, in a manner conventional to winding mandrels.

The mandrel 12 is supported horizontally at opposite ends for rotation about its longitudinal axis A, with the location of the axis fixed relative to the supporting structure 10. To facilitate different shaped mandrels and the operation of the clamping jaw 22, the mandrel is supported at each end by rotating head mechanisms, one head mechanism 24 being shown in FIGS. 1 and 2, supported on a rotatable spindle 26 by a bearing block 28. The spindle 26 is rotatably driven by a bevel gear 30 from a driving gear 31 on the end of an output shaft 32 from a gear box 33, all carried by the supporting structure 10. The drive for the gear box comprises an electric motor 34 secured to the structure and coupled to an input shaft 35 by a coupling 36. If desired, a clutch coupling can be utilized. A second output shaft 37 from the gear box 33 rotates in the same direction as the shaft 32 and drives the pressure roll 14 through a control mechanism or phase changer 38 that varies the angular velocity of the presser roll, as will be described subsequently.

In the preferred embodiment, the mandrel 12 is more than double the length of the tube to be wound, affording a mandrel portion along which the tube can be slid axially after winding, for curing. After the tube is moved axially, as by an axially movable finger (not shown) that engages one end of the tube, heated pressure plates (not shown) can be applied against the outside surface of the tube to cure the adhesive that bonds the convolutions. This occurs while the mandrel is stationary, preferably during the time a new sheet is fed to the mandrel, for winding.

The presser roll 14 is supported horizontally above the mandrel 12, with its central longitudinal axis B parallel to the axis A of the mandrel. In the embodiment shown, the presser roll has three lobes 40, 41, 42. The shape of the roll will be described in more detail in connection with FIGS. 6 9. The presser roll 14 is supported at opposite ends for rotation about the axis B by two stud shafts 44, 45, each of which is journaled in a forwardly extending portion of a pivoted presser arm 48, 49. The stud shaft 44 extends through the presser arm 48 and supports a toothed pulley wheel 52 on its distal end. The pulley wheel 52, shaft 44 and presser roll 14 are in fixed relationship so that rotation of the pulley wheel drives the presser roll about the axis B. Each presser arm 48, 49 has a bifurcated end 48a, 49a, respectively, that straddles a support pedestal 54, 55, respectively, and each is supported on a hollow pivot shaft 58, 59 that projects from opposite sides of the respective pedestal 54, 55. The pedestals, in turn, are secured to the support structure 10. A pin 60 extends through the bifurcated end 48a of the presser arm 48 and pivotally connects the presser arm to the end of a vertically disposed piston rod 61. The piston rod 61 extends upward from a double-acting fluid-actuated cylinder 62, pivotally supported at its lower end to the supporting structure 10. Similarly, a pin 65 in the bifurcated end 49a of the presser arm 49 connects the arm to the end of a piston rod 66 from a double-acting fluid cylinder 67 secured to the supporting structure 10. The fluid cylinders 62 and 67 can be operated to withdraw the piston rods and thereby pivot the presser arms and lift the presser roll 14 from the mandrel 12, for example, during the removal of a wound tube. During a winding operation fluid pressure is applied to extend the piston rods to yieldably bias the presser roll 14 against the mandrel 12 and the convolutions formed from the sheet being wound.

The presser roll 14 is driven from the drive shaft 37, the control mechanism 38 and a shaft 70 driven by the mechanism 38. The shafts 37 and 70 extend through the hollow pivot shafts 58, 59, respectively, in the pedestals 54, 55. A toothed pulley wheel 71 is secured to the extending end of the shaft 70, fixed against relative rotation. A timing belt 72 connects the pulley wheel 71 with the pulley wheel 52, so that the arms 48, 49 can pivot and rotation of the drive shaft 37 will drive the presser roll 14. The pulley wheels 71 and 52 are of equal size, as are the gears 30, 31. Thus, when the shafts 32 and 37 are driven at a particular rotational speed, the presser roll 14 and the winding mandrel 12 are driven at such speeds. By virtue of the mechanism 38, the direction of rotation of the presser roll is opposite to that of the mandrel when the shafts 32, 37 are driven in the same direction, and the angular velocity or rotational speed of the presser roll 14 is varied relative to that of the mandrel during each complete revolution of both to provide equal surface or peripheral velocities of the presser roll and mandrel at the line of mutual contact. The variation in rotational speed of the shaft 70 is in direct relationship to the change in the radius of the roll relative to that of the mandrel at the line of contact. In the preferred embodiment, this change in speed is accomplished through a continuous phase shifting produced by the differential mechanism 38. The driven shaft 37 drives, through a coupling 73, an input shaft 74 that is journaled in a stationary housing 75 supported by the structure 10 (FIGS. 1 and 4). The input shaft 74 has a fixed bevel gear 76 that drives another bevel gear 77 on the end of an aligned output shaft 78, journaled in housing 75, through pinions 79 freely rotatable in a casing 80 rotatably supported by the shafts 74, 78. The output shaft 78 is connected by a coupling 81 to the shaft 70. Thus, when the casing 80 is stationary, the shafts 78 and 70 are driven by the shafts 37 and 74 in an opposite direction therefrom but at the same speed. During any rotation of the casing 80, the rotational speed of the shafts 78 and 70 will be slower or faster than that of the shafts 37 and 74, depending upon the direction of casing rotation.

A reciprocable rack 84 extends within the housing 75 in a guidway 85, and meshes with a spur gear 87 fixed to the basing 80. The rack extends out of the housing and is biased outwardly by a compression spring 88. The rack carries a cam 92 fixed to a rotatable shaft 93 supported by bearing blocks 94, 95 on the support structure 10. The shaft 93 and cam 92 are rotated by a toothed pulley wheel 97 driven by a timing belt 98 from a toothed pulley wheel 99 of the same size fixed to the shaft 37. Depending upon the shape of the cam 92, the rack is reciprocated to varying extents and at varying rates in timed relationship to the rotation of the shaft 37, which is driven at the same speed as the mandrel. Accordingly, the presser roll rotational speed will be varied relative to the mandrel speed by the cam 92. The shape of the cam 92 used with the presser roll and mandrel 12, shown, is such that the speed of the presser roll varies relative to that of the mandrel in the relationship shown in FIG. 5, which will be referred to in more detail in connection with FIGS. 6 to 9.

A specific shape of a winding mandrel 12 and a presser roll 14 for winding a right-isosceles triangular-shaped tube is shown in detail in FIGS. 6 to 9 of the drawings, which also illustrate the manner in which the presser roll coacts with the mandrel to maintain surface contact during winding of a sheet about the mandrel, through 180° of rotation. FIGS. 6 to 9 show four progressive positions, beginning at a point of contact between the mandrel and presser roll at the center of the hypotenuse 18c of the mandrel, and ending at the right angle apex 19a, opposite the hypotenuse. For illustrative purposes, increments of corresponding peripheral distances about the perimeters of the mandrel and presser roll through 180° are indicated by imaginary lines C1 to C17 radiating from the central axis A of the mandrel and by imaginary lines D1 to D17 radiating from the central axis B of the presser roll. It will be readily apparent from FIGS. 6 and 9 that the perimeters of the mandrel and presser roll are equal. It will also be evident that the distances from the axes A and B to the respective surfaces of the mandrel and presser roll along the different imaginary lines C and D varies, and in any fixed plane, such as the imaginary plane P, that passes through or contains the axis A of the mandrel and the axis B of the presser roll, the actual radial distance of the mandrel surface from its axis and the presser roll surface from its axis will continually change during rotation of the two. The radial dimension is smallest for the mandrel along the lines indicated C1 and C12, and is greatest at the line C7 that bisects the corner 19d. Conversely, the radial dimension of the presser roll is largest along the lines D1 and D12 and smallest along the line D7. Thus, it will be understood that the surface profile of the presser roll 14 varies in distance from the axis B inversely from that of the mandrel, with rotational displacement in an opposite direction from that of the mandrel, when in the relationship depicted.

As will be appreciated from the different degrees of rotation shown in FIGS. 6 to 9, in which the positions of the axes A and B have not changed, the sum of the distance from the axis A to the surface of the mandrel 12 and the distance from the axis B to the surface of the presser roll 14, at equal peripheral distances from the reference lines C1 and D1, is constant. As a result, when the mandrel 12 and roll 14 are rotated about their respective axes at essentially equal peripheral speeds in opposite rotational directions, the surfaces can be maintained in contact without relative movement of the axes.

Considering the diagram of FIG. 5 along with FIGS. 6 to 8, it can be seen that the rotational speed of the presser roll is varied relative to that of the mandrel in order to maintain equal peripheral velocities. The curves identified as "Presser Roll" and "Mandrel" in FIG. 5 show the angular displacement of each in degrees at increments of a given cycle time t during which both are rotated 360°. The relative angular velocities of the two at any given time are indicated by the slope of each curve.

Each of the four positions illustrated in FIGS. 6 to 9 is indicated on the diagram of FIG. 5, at F6, F7, F8 and F9 respectively. FIG. 6 is taken as a reference position of zero displacement. The mandrel 12 is rotated at a constant velocity throughout each cycle, ignoring start up acceleration. The generally slower, then faster, then slower, presser roll speed through 180° displacement is readily apparent from the curves, as are the positions of equal angular displacement, indicated by the curve intersections.

In the FIG. 7 position, while the peripheries of the mandrel and presser roll have moved equal distances, as shown by the aligned lines C7 and D7 in the plane P, the mandrel has rotated approximately 65° and the presser roll approximately 72°, as shown both in FIG. 7 and the displacement diagram of FIG. 5.

In the FIG. 8 position the surfaces have moved equal distances to where the lines C13 and D13 are aligned in the plane P. The mandrel has rotated through 135° while the presser roll has rotated 150°. In FIG. 9, each has rotated 180° in one-half of the cycle, as indicated at time t/2 in FIG. 5.

As already indicated, this difference in the extent of angular rotation of the presser roll relative to the mandrel at all times during a complete cycle, except the four instances indicated by the intersection of the curves in FIG. 5, and the change in angular velocity of the presser roll during its rotation, are produced through rotation of the casing 80 by the cam 92. The shape of the cam is such that when rotated at the constant speed of the mandrel 12 it rocks or partially rotates the casing 80. When the casing is rotated in the same direction as the input shaft 74, the angular velocity of the presser roll is less than that of the mandrel. This is indicated by those portions of the presser roll curve in FIG. 5 that have a smaller slope than that of the mandrel curve at a given time. Conversely, when the casing is rotated in the opposite direction from the input shaft, the presser roll is rotated at a greater angular velocity than the mandrel. The periphery of the cam 92 is contoured to reciprocate the rack 84 in accordance with the relative change in radial length of the presser roll and mandrel, increasing the speed of presser roll rotation as the radial length of the roll diminishes relative to that of the mandrel in the plane P, and decreasing the speed of presser roll rotation as the radial length of the presser roll increases relative to that of the mandrel. The precise shape of the cam 92 depends of course upon the particular shape of the mandrel and presser roll, but can be readily determined with suitable accuracy by incrementally determining the relative angular velocity required of the presser roll to advance its periphery an increment equal to that advanced by the mandrel during a given time, provided that the increments are small relative to the total peripheral length. By way of example only, 32 increments about a mandrel and presser roll each having perimeters of approximately 7 inches were found satisfactory in the present embodiment for determining the relative velocities necessary to maintain essentially equal peripheral speeds in a plane of mutual contact.

In each of FIGS. 6 to 9, the constant distance between the axes of the presser roll and mandrel is indicated by the lines F and G that pass through the axes and are equidistant in each FIG. The actual distance between the axes A and B, as shown in FIGS. 6 to 9, is constant only until a sheet is wound about the mandrel 12. As a sheet is wound, the thickness of the sheet and each successive convolution requires a somewhat greater spacing between the axes. This is illustrated in FIG. 10, which shows the axis B raised above the imaginary line F, by the thickness of the convolutions of the sheet S about the mandrel 12. The displacement of the presser roll is accommodated by the presser arms 48, 49 and the yieldable biasing force created by the fluid cylinders 62, 67.

Referring now to FIGS. 1 to 3, it will be seen that the sheet S to be wound is supported during winding by the vacuum table 16, in the plane of the slot 21 of the mandrel, when the mandrel is oriented as shown in FIG. 2. The vacuum table is comprised of a plurality of vacuum boxes 100, an end box 100a being located closely adjacent the winding mandrel 12. All of the vacuum boxes have a flat, upper, surface 102 in a common plane. The boxes are directly adjacent one another, side by side, are generally rectangular in shape, and extend substantially the length of the mandrel to provide a support for the sheet being wound. Opposite ends of the boxes are secured to a common support 104 at one end and 105 at the other end. Each support has a tubular aperture 106, 107, respectively and is received on a horizontal mounting rod (not shown). In general, it is not necessary that the entire support length of the vacuum boxes be constructed to create a pressure differential between the upper and lower surfaces of the sheet being supported, and for that reason only a limited area of each box is provided with apertures 108 in the flat upper surface 102. The end of each box supported by the support 105 communicates through an opening 109 in the lower surface, to a coupling 110 and an exhaust conduit 111. The boxes are preferably obstructed at the opposite side of the apertured portion from the openings 109, by blocks 112. An additional vacuum box 114 is provided, that is movable in a direction parallel to the mandrel, and is used to transport a sheet of paper to be wound from a receiving position adjacent the end 104 of the vacuum boxes, onto the vacuum boxes, and at the same time sliding one edge of the sheet along the slot 21 of the mandrel, so that the sheet is engaged in the winding mandrel when positioned. The movable vacuum box is separately connected with a flexible conduit to the source of reduced pressure. When a vacuum is applied to the table through the conduits 111, the reduced pressure beneath a portion of the sheet supported on the vacuum boxes retards movement of the sheet, which must slide across the boxes during winding, and thereby places the sheet in tension as it is wound.

To summarize the operation of the apparatus, a sheet S to be wound into a tube of noncircular cross sectional shape is fed along the support frame 10 in a direction parallel to the mandrel 12, onto the vacuum table 16. At the same time, one end of the sheet is inserted into the mandrel slot and gripped by the clamping jaw 22. A vacuum is applied to the table 16 to resist movement of the sheet relative to the table during winding and fluid pressure is applied to the cylinders 62, 67 to bias the presser roll 14 against the mandrel 12. The mandrel and presser roll are then driven in opposite directions by the electric motor 34 and through a plurality of revolutions at relative angular velocities that differ in accordance with the slopes of the curves of FIG. 5. As the sheet is wound, adhesive is applied to the upwardly facing surface of the unwound portion as it passes beneath the spray or quasi-spray applicator 17. During rotation, the presser roll 14 continuously presses against the convolutions of the sheet that are wound about the mandrel. This pressure is applied progressively over the entire surface, without oscillation of the presser roll axis and with little or no slippage between the presser roll and sheet. As the sheet S is progressively wound about the mandrel, the axis of the presser roll is gradually moved farther away from the axis of the mandrel by the increased thickness of the tube wall being formed. This movement of the presser roll away from the mandrel is yieldably resisted by the fluid pressure of the cylinders 62, 67. The biasing force of the fluid pressure plus the absence of oscillation of the presser roll assures that the pressure exerted by the presser roll upon the sheet being wound is continuous. Further, any effective increase in surface speed of the tube being wound by virtue of the increased radius created as convolutions are added will tend only to increase the peripheral speed of the tube surface relative to the presser roll, so that at no time is the presser roll rotating at a greater peripheral speed than the mandrel at the point of contact with the tube, which would tend to loosen the convoluted plies. When the sheet has been completely wound about the mandrel 12, rotation of the mandrel and presser roll is stopped by either deenergizing the motor 34 or declutching the drive. Fluid to the cylinders 62, 67 is reversed and the presser roll is raised from the mandrel and wound tube. The clamping grip on the leading end of the sheet engaged by the mandrel is released and a finger is moved along the mandrel, sliding the wound tube either off the mandrel or to an axially displaced portion of the mandrel for curing, and is returned. Another sheet is then moved onto the table 16, gripped by the mandrel, and the cycle is repeated.

As will be evident from the described embodiment of this invention, an improved winding mechanism has been provided in which a tube of non-circulqr cross sectional shape can be convolutely wound at high speeds while substantially uniform continuous pressure is applied against the convolutions by a presser roll rotating at a peripheral speed equal to that of the winding mandrel at the location of contact with a sheet being wound to improve interply bonding and shape retention and thereby provide an improved product capable of being manufactured at high production rates. While a preferred embodiment of this invention as been described in detail, it will be apparent that various modifications or alterations may be made therein, without departing from the spirit and scope of the invention set forth in the appended claims. For example, it will be appreciated that mechanisms of different construction and operation than the differential mechanism described herein can be used to accomplish the phase shift or change the angular velocity of the presser roll relative to the mandrel, and tubes of different cross sectional shapes, such as rectangular shapes, can be wound in the same manner as described herein, using a mandrel and follower roll of suitable shapes and an appropriately contoured control cam. It will also be apparent that tubes can be wound in the manner disclosed herein from a plurality of separate sheets, with any sheet subsequent to the first being secured at its leading end as well as throughout its surface by adhesive, or the apparatus can be used to form a cover ply into a tubular shape. For example, a separate sheet can be applied as a label to a wound tube or to a container received on the mandrel for labeling.