US 3616078 A
Description (OCR text may contain errors)
l? Patent  Inventor  APPARATUS AND METHOD FOR WRAPPING TAPE 0N MULTISIDED ARTICLES 3 Claims, 8 Drawing Figs.
 U.S.Cl 156/486, 156/446, 242/721  llnt.Cl B65c 3/12, B65c 9/02 [501 Field of Search 156/475,
 References Cited UNITED STATES PATENTS 3,076,493 2/1963 Berg 156/446 3,238,080 3/1966 Sghluter 156/542 X 3,362,864 1/1968 Johnson 156/475 X 3,476,327 11/1969 .lawter H 242/721 X Primary Examiner Benjamin A. Borchelt Assistant ExaminerJ. J. Devitt Attamey-George E. Pearson ABSTRACT: Apparatus for, and method of, wrapping tape around a multisided article, employing a yieldably supported roller and a mechanism which feeds said tape between the surfaces of the article and said roller as the latter is moved over said surfaces. After the roller has traveled diagonally across one side of the article and pressed tape thereon, the article is rotated to bring the next adjacent side into position for taping, while the roller is held against the surface of the article by the yieldable action of the means provided for supporting the roller and by the programmed movement of the roller at a predetermined rate in the direction of rotation of said article. Through repetition of the aforesaid steps, tape is wrapped around the article at a selected angle relative to its longitudinal axis.
PATENTEUnm' 26 I97! FIG. 1.
JAM ES 5. HOWARD PATENTEnum 26 197i SHEET 2 OF d INVENTQR.
JAMES 5. HOWARD BY t a a g a I ATTORNEY PATENTEmm 2s l9?! 3, 6 1 6 0 T8 sum 3 BF 4 JAMES S. HOWARD FIG. 4 EM 9M4- ATTORNEY PATENTEUUBT 28 197] 3,616,078
SHEET b [1F 4 INVENTOR JAMES S. HOWARD awgxmi' ATTORNEY APPARATUS AND METHOD FOR WRAPPING TAPE ON MIUIL'IISIDED ARTICLES BACKGROUND OF THE INVENTION This invention relates to both an apparatus and a method for wrapping tape around a multisided article, and more particularly to an apparatus and a method which are adapted for automatically wrapping tape around a laminated structural member in precisely spaced, adjacently disposed strips.
Laminated structural members have recently found increased use in the construction of various articles which must have a high strength-to-weight ratio, such as spars used in aircraft. In the fabrication of such components, it is often clarity to wrap strips of resin-impregnated fiberglass tape diagonally around the periphery of a structural member having a square or rectangular cross section. This operation has heretofore generally been performed manually, which method is unsatisfactory because of the excessive amount of time and cost involved and also because of the lack of uniformity in the products produced thereby. Hence the invention disclosed herein, which as has been mentioned pertains to both an ap paratus and a method for automatically wrapping laminated structural members, has particular utility in the fabrication of lightweight beams and the like, although the invention is not limited thereto.
SUMMARY OF THE INVENTION As described in detail hereinafter, apparatus constructed in accordance with the principles of this invention comprises means for yielding supporting and moving a pressure roller over the surface of an object about which tape is to be wrapped, the words resiliently supporting referring 45 arrangement pressure roller being maintained against the surface of said object as the latter is rotated during the tapewrapping method associated with the apparatus. More particularly, a preferred apparatus embodiment of being invention is provided with an elongated bed consisting of a pair of horizontally disposed ways, and a carriage slidably mounted on said ways and movable in opposite directions therealong by means of a rack and pinion arrangement. A horizontally disposed beam is slidably mounted on the aforesaid carriage for movement along its own longitudinal axis in a direction perpendicular to the ways of said bed, said beam also being driven by a rack and pinion mechanism. One end of a support arm is pivotally mounted on the aforesaid beam for rotation about a horizontal axis, and means are provided for yieldably biasing this support arm to rotate in one direction about said axis of rotation thereof. Pivotally mounted on the free end of the support arm for rotation about an axis perpendicular thereto is a support member which carries a pressure cylinder, the longitudinal axis of this cylinder illustrated coincident with said axis of rotation of said support member and pressure roller having a resilient rim being mounted on the end of the extensible shaft of the cylinder. The support member also carries a tape-feeding assembly which is adapted to feed tape between the pressure roller and the surfaces of the object around which said tape is to be wrapped, as well as a tapecutting assembly arranged for cutting the tape fed to said pressure roller.
To wrap tape around a multisided article by means of the abovedescribed apparatus, the article is first mounted between centers and the aforesaid carriage and beam are positioned so that pressure roller carried by in beam is adjacent the surface of said article at one end thereof. Tape is fed under the pressure roller as the latter moved obliquely across the surface of a first side article by the simultaneous movement of said carriage and beam. When the pressure roller reaches an edge of the article it is stopped and the article is rotated to bring a second side thereof into position for taping, said beam being simultaneously moved in the direction opposite its direction of motion during the aforesaid oblique movement of the pressure roller across the first side of the article. As mentioned hereinbefore, the support arm which carries the pressure roller is yieldably biased to rotate in one direction about its point of attachment. This arrangement, together with the programmed movement of pressure roller during the rotation of the article being wrapped, maintains the pressure roller in contact with said article throughout its rotation. When the article has reached a predetermined position its rotation is stopped, and tape is again fed under the pressure roller as the latter is moved obliquely across the surface of the next adjacent side of the article by the simultaneous movement of the carriage and beam mounted on the latter. By repeating the steps which have been briefly described, tape is wrapped around the article at a selected angle relative to its axis of rotation on the aforementioned centers.
OF THE INVENTION Accordingly, it is an object of this invention to provide an effective means and an efficient method for wrapping tape around an article of manufacture.
Another object of the invention is to provide apparatus capable of wrapping tape around an object in precisely spaced, adjacently disposed strips.
Still another object of the invention multisided to provide a method of wrapping tape upon a multisided workpiece, which method is adapted for automation.
A further object of the invention is; to provide apparatus which can wrap layers of adjacently disposed strips around a laminated structural member at different angles relative to one another.
BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:
FIG I is a pictorial view illustrating a preferred embodiment of the invention:
FIG. 2 is a side elevation of certain components of the apparatus depicted in FIG. ll;
FIG. 3 is a front elevation of the same components, taken along the plane represented by the line designated 3-3 in FIG. 2 and in the direction indicated therein, certain components being removed from the apparatus for clarity;
FIG. 4 is a detail view of certain components, illustrating them in a position different from that shown in FIG. 2; and
FIGS. 5 through 8 are diagrammatic representations of a pressure roller of the apparatus as illustrated in FIGS. I-4 and the cross section of a box beam wrapped by said apparatus, different positions assumed by said roller and box beam during the steps of the disclosed wrapping method being illustrated therein.
Throughout the drawings and the following specification like numbers designate like parts.
DETAILED DESCRIPTION As illustrated in FIG. 1, a preferred apparatus embodiment of this invention comprises an elongated bed which is generally designated in the drawing by the number and which is provided with a pair of parallel ways 12A, 128 on which a carriage 14 is slidably supported. Carriage 14 is driven in opposite directions along bed 10 by means of a pinion (not shown) carried by said carriage and engaged with a rack 16 attached to said bed. Slidably mounted on carriage 14 for movement along its own longitudinal axis is a beam 18, a second pinion (not shown) being carried by said carriage and engaged with a rack 20 attached to said beam to move the latter in opposite directions along said longitudinal axis thereof. The front, lower portions of beam 18 and rack 20 are covered with an extensible bellows 22.
Mounted on the upper surface of beam 18 at the forward end thereof are two supports (only one of which is seen in FIGS. I and 2 and which is generally designated therein by the number 24). More particularly, the two supports 24 are disposed in spaced, parallel relations and each comprises two L-shaped sections 26, 28, one arm of each lower section 26 being secured by means of machine screws 30 to beam 18 and one arm of each upper section 28 being joined by means of machine screws 32 to a respective one of said lower sections. Pillow blocks 34A, 34B are respectively secured by means of machine screws 36 to the horizontally extending arms of the aforesaid sections 28, and a shaft 38 is journaled in said pillow blocks for rotation about an axis disposed perpendicular to the longitudinal axis of beam 18. One end of a support arm 40 is positioned between the two supports 24 and fixedly attached to shaft 38 by conventional means which are not shown for the sake of simplicity. The longitudinal axes of beam 18 and support arm 40 are coplanar in a vertical plane.
As can best be seen in FIG. 2, a U-shaped support member 42 is fixedly mounted on the forward end of beam 18 and pivotally supports a pressure cylinder 44 for rotation about an axis disposed perpendicular to the longitudinal axis of said beam and support arm 40. Projecting from one end of pressure cylinder 44 and fixedly secured to the piston (not shown) therein is a drive shaft 46 the free end of which has a U-shaped connector 48 threadedly attached thereto, which connector is in turn pivotally connected by means of a pin 50 to a lug 52 fixedly joined to the lower side support arm 40. To bias support arm 40 so that it tends to rotate in the clockwise direction as viewed in FIG. 2, the interior of pressure cylinder 44 is pressurized by conventional pnuematic or hydraulic pressurizing means (not shown).
FIGS. 2 and 3 most clearly show the structure of a support bracket (generally designated in said drawings by the number 54) which is fixedly secured to a forward end plate 56 of arm 40 by means of a plurality of machine screws 58. More specifically, support bracket 54 comprises a first section 60 a projecting portion of which rotatably fits within a bore 62 formed in forward end plate 56 (said machine screws 58 locking said first section in a selected position relative to said forward end plate), a second section 64 disposed parallel to the longitudinal axis of support arm 40, and a pair of braces 66A, 66B welded to said first and second sections. Generally designated in the drawings by the number 68 is a support member comprising an annular member 70 the lower edge of which rotatably fits within a counterbore 72 of a hole 74 which extends through the aforesaid second section 64 of support bracket 54. Machine screws 76 extend through holes in said second section 64 and are threadedly engaged within selected ones of a plurality of holes in member 70 to thereby lock support member 68 at s selected angular position relative to support arm 40. Support member 68 also includes a plate 78 which is disposed perpendicular to member 70 and fixedly attached thereto by suitable means such as welding (a brace 80 being fixedly attached to said plate and disk to impart increased rigidity to the assembly). An elongate arm generally designates in the drawings by the number 82 is comprised of a first section 84 which passes through the hole 74 in the second section 64 of support bracket 54 and the hole in member 70 and which is fixedly attached by suitable means to said plate 78, and a second generally L-shaped section 86 one arm of which is integrally joined to said first section 84 and depends therefrom. Attached to arm 82 by means of machine screws 88 is a pressure cylinder 90 the longitudinal axis of which coincides with the axis of rotation of member 70. The centrally disposed drive shaft 92 of pressure cylinder 90 is threadedly connected at the outer end thereof to a generally L-shaped member 94, the opposite sides of which slidably abut a pair of guide bars 96A, 96B mounted on plate 78. Member 94 carries at its upper end a pressure roller, generally designated by the number 98, which has a resilient rim 100 and which rotates about an axis perpendicular to the longitudinal axis of support arm 40. Conventional pressurizing means (a portion of which is designated in FIG. 3 by the number 102) are connected to pressure cylinder 90 to selectively extend and retract drive shaft 92 and thereby move pressure roller 98 between a first position thereof which is illustrated in FIG. 4 and a second position thereof which is illustrated in FIG. 2.
The embodiment of the invention which is herein described also includes a tape feeding assembly comprising a tape supply drum 104 rotatably mounted on arm 86 and a spool 106 which is also rotatably mounted on said arm and the rotation of which is synchronized with the motion of said tape supply drum by means of a belt 108 engaged with pulleys attached to said drum and spool. One surface of the tape 110 wound on drum 104 is coated with an adhesive and covered by a tape 1 12 which is peeled from said surface and wound on spool 106 as tape 110 is unwound from the drum 104. The tape-feeding assembly also includes a flat slide member 114 which is slidably mounted between two parallel slide plates 116A, 1168 fixedly attached to the side of plate 78 adjacent pressure cylinder 90, said slide member being movable between a first position thereof which is illustrated in FIG. 2 and a second position thereof which is illustrated in FIG. 4. To drive slide member 114 between said first and second positions thereof, the apparatus is provided with a pressure pressure 118 which is attached by suitable means to the side of plate 78 facing away from pressure cylinder 90 and the drive shaft of which is connected by means of a lug 122 to said slide member through a slot 124 formed in plate 78. The slide member actuation system also comprises conventional pressurizing means (a portion of which is designated in FIG. 3 by the number 102) connected to pressure cylinder I18 and adapted to drive the piston (not shown) to which shaft is attached in opposite directions within said cylinder. Slide member 114 carries an elongate tape guide member 126 in the form of a trough the width of which is substantially equal to the width of tape I10 and one end of which is positioned adjacent the upper periphery of pressure roller 98 when the latter is positioned in the aforesaid first position thereof illustrated in FIG. 4, and said slide member is positioned in the aforesaid second position thereof illustrated in the same drawing. A spring-biased arm 128 hold tape 1 10 against tape guide member 126.
The tape-feeding assembly also comprises a tape feed control mechanism formed of a first feed roller 130 rotatable mounted end slide member 114, a ratchet wheel I32 fixedly attached to said first feed roller, a pawl I34 which engages said ratchet wheel and allows said first feed roller to turn in a counterclockwise direction only as viewed in FIG. 2, and a second feed roller 136 rotatably mounted on one end of an L- shaped arm [38 which is in turn pivotally mounted on slide member 114 and biased by means of a spring 140 so as to move said second feed roller toward said first feed roller. An idler roller 142 is rotatably mounted on plate 78 adjacent the aforedescribed tape feeding assembly to align tape 110 with tape guide member 126. During the operation of the apparatus, tape 110 extends from drum 104 to idler roller 142 and thence between rollers 130, 136 ro tape guide member 126.
Also illustrated in FIG. 2 is a tape-cutting assembly mounted on plate 78 between pressure roller 98 and slide member 114. More particularly, the aforesaid tape-cutting assembly comprises a vertically disposed bar 144 which has a cutting edge at the upper end thereof and which is slidably engaged within a hole in a guide member 146, and a pressure cylinder 148 which is mounted on plate 78 and which contains a piston (not shown) to which bar 144 is connected. Conventional pressurizing means (a portion of which is designated in FIG. 3 by the number 102) are connected to pressure cylinder 149 to drive bar 144 between a first position thereof illustrated in FIG. 4 and a second position thereof illustrated in FIG. 2, the line of travel of said bar intersecting the line of travel of tape 110 to pressurize roller 98 so that the tape is cut when the bar moves to said second position thereof.
During the wrapping of multiple layers of tape around a workpiece by means of the disclosed apparatus, it may be necessary to remove screws 76 from support member 68 and support bracket 54 so that said support member can be rotated to a new position relative to said support bracket. Hence there is provided a plate 150 which is fixedly mounted on plate 78 of support member 68 and which depends therefrom to a point contiguous to the edge of the section 64 of support bracket 54. A spring-biased plunger 152 extends through a hole formed in plate ll5ill adjacent the lower edge thereof, the inner end of said plunger entering one of a number of dimples formed in the edge of said section 6d when support member fail has been turned to register the plunger with a selected dimple, which arrangement facilitates the proper positioning of said support member at different positions relative to support arm All). Screws 7e are of course employed to lock support member 6% to support bracket 54 when the apparatus is in use.
in FllG. l is illustrated a box beam, hereinafter referred to as workpiece llfid, which for clarity is cut away in the drawing at the point where pressure roller 9% makes contact therewith. Workpiece ram is mounted between two centers (only one of which is illustrated in FllG 11 and which is designated therein by number llfitfr) for rotation about its longitudinal axis. Also illustrated in the same drawing is a control console 1158 constituting a portion of a numerical control system which is programmed to move carriage M, beam 118, and other moving parts of the apparatus during process steps in accordance with the invention, as disclosed hereinafter. Since the principles of numerical control are well known in the art and do not constitute a part of the present invention, details of the electrical equipment used to control the disclosed apparatus are omitted.
OPERATION By means of the illustrated apparatus adhesive-coated tape can be wrapped around workpiece 1541 in precisely spaced, parallel strips disposed at any desired angle relative to the longitudinal axis of said workpiece. FOr example, to wrap strips on workpiece 15d at an angle of 45 relative to the longitudinal axis thereof, carriage l4 and beam 18 can be moved to position pressure roller 9% adjacent one edge of a first side thereof, with said pressure roller being under workpiece as illustrated in FIG. II and in the aforesaid first position thereof illustrated in FIG. 4 and with support member 6% locked at an angle of 45 with respect to the longitudinal axis of support arm 4t). (For the purpose of illustration, it will be assumed that pressure roller 93 is initially positioned below the edge of workpiece 1154 which is rearmost in H6. 1 and that tape 1110 is to be wrapped around the workpiece starting from a point adjacent the end thereof which is on the right in the same drawing.) Tape llltl is fed over pressure roller 9% by actuating cylinder llllii so as to drive slide member lid toward said pressure roller and bring the end of tape guide member 1126 close to the upper periphery thereof as illustrated in FIG. d. It should be noted at this point that tape lit), being held against guide member 11% by means of arm IN, is unwound from drum ltld as slide member lid is moved toward pressure roller 9d, and also tape lid is initially extended beyond the end ofsaid guide member so that it lies over the pressure roller when the slide member is in the aforesaid second position thereof adjacent pressure roller 98. As previously mentioned, tape I112 is peeled from tape lid and wound on spool 1106 as tape lllfl is unwound from the drum lltld. Cylinder 9b is next actuated to move pressure roller 9%! upward, thereby pressing the adhesivewoated side of tape lliltl against the lower surface of workpiece llEid as illustrated in FIG. 5. Selected pressures are maintained in cylinder 90 and cylinder did when pressure roller ft is in contact with tape I and the latter is thereby pressed against workpiece E54. Carriage 1141 is then moved toward the end of the bed Ml which is on the left in FIG. l as beam llfl is moved at the same rate in a forward direction on said carriage (i.e., to the left in FIG. ll), thereby moving pressure roller E li in a first direction across workpiece d at an angle of 45 with respect to the longitudinal axis thereof. The motion of pressure roller 98 is lengthwise of tape 11110, which is pulled from the drum 11M as said pressure roller rolls toward the forward edge of workpiece I154 and presses the tape against the lower surface of said workpiece.
When pressure roller 98 reaches the end of the planar portion of the side of workpiece I54 which is designated by the number II in FIG. 55, the aforesaid motions of carriage M and beam 118 are stopped, at which time the pressure roller and workpiece are in the configuration illustrated in FIG. 6 Workpiece llEd is then rotated in the direction counter to the first direction of motion of pressure roller 98 across side one of said workpiece, that is, the rotation of the workpiece is counterclockwise as viewed from a point located to the right of the point at which said workpiece is broken away in FIG. I, whereas the motion of the pressure roller in said first direction thereof is clockwise of the workpiece when viewed from the same point (the motion of said pressure roller longitudinally of the workpiece when it moved in said first direction being disregarded in defining the direction of rotation of workpiece llfi l as counter" to that of pressure roller 9% in the first direction of motion thereof. As workpiece 1154 is rotated through an angle of 45 to bring it into the position illustrated in FIG. 7, beam id is moved at a predetermined rate rearwardly on carriage l4 and simultaneously support arm 40 is rotated in a counterclockwise direction as viewed from a point located on the right side thereof in FIG. I, the rotation of said support arm being effected by the pressure exerted against pressure roller 98 as the edge of side one of workpiece I54! which is on the left in FIGS. 5 and 6 moves along the path indicated in phantom in FIG. 7. The piston of pressure cylinder id is of course pushed inwardly of said cylinder as support arm 410 is rotated as described. l-Ience fluid (air or liquid, depend ing upon the type of pressurizing system which is employed) is bled from cylinder 44 as arm dill is depressed; then as workpiece i5 3 continues to rotate counterclockwise from the position illustrated in FIG. 7, fluid is injected into the cylinder in order to move arm upward, beam Ill; meanwhile continuing to move at the aforesaid predetermined rate rearwardly on carriage Ml. The aforementioned rearward motion of beam Ill and the yieldable action or arm 40 keep pressure roller 98 pressed against the surface of workpiece 154 as it rotates. Furthermore, the rate at which beam id is moved rearwardly on carriage MI is such that the pressure roller 98 has rolled around the edge between side one and side two of workpiece 1154 and reached the planar portion of side two of workpiece 1154 when the latter has rotated 90, as illustrated in FIG. ti. By again moving carriage Id toward the left end of bed It) and beam It in a forward direction at the same rate as has been described in connection with the motion of pressure roller 9% in the aforesaid first direction thereof, the pressure roller is moved in a third direction across side two of workpiece 15d, which third direction is parallel to said first direction (i.e., disposed at an angle of 45 with respect to the longitudinal axis of the workpiece). By repeating the foregoing steps, tape I10 is wrapped around all sides of workpiece I541 along the length thereof. Just before pressure roller 9% reached the point on the workpiece where wrapping is to be terminated, cylinder llllti is actuated so as to drive slide member llll4l to the aforesaid first position thereof which is illustrated in FIG. 2. Cylinder Mt is immediately thereafter actuated to drive bar M4! from the aforesaid first position thereof illustrated in FIG. d (in which first position said bar is of course maintained during the time tape llllll is fed to pressure roller 9%) to the aforesaid second position thereof illustrated in FIG. 2, thus cutting tape lllltl. The motion of pressure roller 9% across workpiece 1541 continues until the end of the tape llllll being wrapped on said workpiece has been pressed against the workpiece. Aftcr one strip of tape Iii) has been wrapped around workpiece 154 along the length thereof, pressure roller 98 is moved away from the surface of said workpiece by actuating cylinder 90 and carriage lld is then returned to the right end of the workpiece and positioned so that a second strip of tape can be wrapped around the workpiece adjacent the first strip. SInce the motions of carriage M, beam l8, and other moving parts of the apparatus are controlled by numerical tape, the wrapping of workpiece 154 is achieved automatically.
As mentioned hereinbefore, support member 68 can be rotated to different angular positions relative to the longitudinal axis of arm d0. Hence the support member 68 can be rotated 90 with respect to its position during the wrapping of tape 110 on workpiece as described hereinbelow, and by proper programming of the motions of carriage l4 and beam 19 a second layer of tape can be wrapped around the workpiece in adjacent strips which are also disposed at an angle of 45 with respect to the longitudinal axis of said workpiece but which run in the direction opposite to that of the strips in the first layer of tape. Other angular orientations of tape 110 are of course readily attainable by means of the disclosed apparatus and method. it should be understood that the utility of the invention is not limited to the wrapping of workpieces having a square cross section or only four planar sides, the shape of the workpiece 154 illustrated in the drawings being chosen for the purpose of example only.
When tape is being wrapped around a workpiece of relatively large cross section at a relatively large angle with respect to the longitudinal axis thereof, the rim 100 of pressure roller 98 will not remain in contact with the surface of the workpiece across the entire width of said rim during the movement of said pressure roller which is shown in FIG, 7 (i.e., during the rotation of workpiece 154), unless the aforesaid rim is of a certain thickness and hardness. More specifically, for a workpiece having a transverse measurement in the range of 12 to 15 inches and for the wrapping of tape 110 at an angle of 45 with respect to the longitudinal axis of the workpiece, it has been found that the thickness of the rim 100 should be at least one-fourth inch and that said rim should be formed of a rubber having a Shore hardness not greater than 50.
The present embodiment of this invention is to be considered in all respect as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes coming within the meaning and range of equivalency of the claims are intended to be embraced therein.
Having thus described the invention, what is claimed as new and useful and desired to be secured by Letters Patent is:
1. Apparatus for wrapping tape on the surface of a workpiece, comprising:
means for supporting and turning said workpiece about an axis of rotation extending therethrough;
means for supporting and moving said carriage in opposite directions along a longitudinal axis extending parallel to said axis of rotation of the workpiece;
means for supporting and moving said beam on the carriage in opposite directions along an axis perpendicular to said longitudinal axis of the carriage;
a support arm;
means pivotally connecting one end of said support arm to the end of said beam nearest the axis of rotation of the workpiece for swinging movement about an axis parallel to said axis of rotation of the workpiece;
a pressure roller;
means supporting said pressure roller on the free end of said support arm for rotation about an axis perpendicular to the longitudinal axis of the arm;
a pressure cylinder operatively attached pivotally at one end thereof to said beam and pivotally attached at the other end thereof to said arm so that the cylinder when pressurized causes swinging movement of the arm to bring the pressure roller into pressurized engagement with a surface of the workpiece and reverse swinging movement of the arm caused by rotation of the workpiece against the roller is permitted by release of pressure in the cylinder;
and means for feeding said tape between said pressure roller and said surface of the workpiece.
2. Apparatus as defined in claim 1 including: said pressure roller supporting means comprising a support member mounted on said support arm for rotation about an axis disposed perpendicular to the axis of rotation thereof;
means for locking said support member at different angular positions relative to said su port arm; a pressure cylinder mounte on said support member so that its longitudinal axis is disposed perpendicular to the longitudinal axis of said support arm;
a piston slidably disposed within said cylinder;
a shaft one end of which is connected to said piston and the other end of which projects from said cylinder, said pressure roller being mounted on the free end of said shaft;
means for maintaining the axis of rotation of said pressure roller in fixed position relative to said support member; and
means for pressuring said cylinder to thereby drive said piston in opposite directions therein.
3. Apparatus as defined in claim 1 wherein said pressure roller has a resilient rim the Shore hardness of which is not greater than 50 and the thickness of which is at least onefourth inch.
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