Patent Publication Number: US-2005116081-A1

Title: Tape winding method and device, and tape winding body

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a tape winding method and device and a tape winding body, and particularly relates to a tape winding method and device and a tape winding body capable of winding a magnetic tape at high speed and making a winding shape favorable.  
      2. Description of the Related Art  
      Various kinds of so-called pancakes (tape winding bodies each with a magnetic tape wound around a winding hub) which are used for cassette tapes and video tapes, and also used for data backup for computers are manufactured by drawing out a wide, belt-shape raw magnetic tape wound in a roll shape from a feeding side and cutting the raw magnetic tape into a plurality of narrow magnetic tapes while conveying the raw magnetic tape, and winding the magnetic tapes around flangeless hubs at a winding side.  
      As such pancakes, it is desired that their wound magnetic tapes be as long as possible in the respect of productivity, and from the same viewpoint, a winding method at the winding speed as fast as possible is desired.  
      As a magnetic tape winding method and device for manufacturing a pancake to cope with such a challenge, there are various conventionally known methods which make high-speed winding possible.  
      For example, according to Japanese Patent Application Publication No. 62-31645, there is proposed a construction of winding a magnetic tape by combining a position restraining roller just before a pancake, and an edge restraining roller and a pressing roller which are in contact with the pancake. According to Japanese Patent Application Publication No. 5-159284, there is proposed a construction which decreases layer down and winding disarrangement of the magnetic tape by three or more of restraining rollers. According to Japanese Patent Application Publication No. 7-296556, there is proposed a construction which makes high-speed winding possible by a head section including a main touch roller in contact with pancake and a guide roller provided just before the main touch roller.  
      Incidentally, in recent years, as a purpose of using a magnetic tape, use for magnetic recording medium of a backup computer becomes a main stream. When using the magnetic tape in such a backup computer, a servo signal is recorded on a surface of the magnetic tape. On this occasion, the winding shape of the pancake before the servo signal is written becomes important. Namely, if the winding shape is unfavorable, the servo signal cannot be accurately recorded, which becomes the disadvantage in quality. If the winding shape is unfavorable, an edge portion of the magnetic tape is easily damaged during storage, transportation and other circumstances.  
      Many of the magnetic tapes in recent years are thin and smooth, and become more difficult to wind as compared with the conventional magnetic tapes. As a result, the above-described defects become the problems.  FIGS. 14A, 14B ,  14 C and  14 D are conceptual views showing each example in which the winding shape of a magnetic tape  1  is unfavorable. In the drawings, sections of pancakes  3  are shown. The pancake  3  is formed by winding the magnetic tape  1  around a winding hub  2 . In each of the drawings, the magnetic tape  1  is wound around the hub  2  by being guided by guide rollers  4  and  4 .  
       FIGS. 14A and 14B  show winding defects in which the magnetic tape  1  cannot be restrained with the flanges of the guide rollers  4  at the time of start. Of the two,  FIG. 14A  is the state  5  in which the magnetic tape  1  protrudes from the flanges of the guide rollers  4  when it is wound on the winding hub  2 , which is also called a protruding defect at the time of increasing speed.  FIG. 14B  is the state  6  in which the magnetic tape  1  protrudes out of the flange from the state in which it is inside the flange of the guide roller  4 .  
       FIG. 14C  is a defect called “irregular winding” among the defections called “winging disarrangement”, and is the state  7  in which an end surface of the magnetic tape  1  is not uniform. The magnetic tape  1  is wound up in the state in which the end surface of the magnetic tape  1  is not uniform, thereby causing another “winding disarrangement” called “end surface abrasion” in which the end surface of the magnetic tape  1  is rubbed by the flange of the guide roller  4  and damaged.  
       FIG. 14D  is the defect called “protrusion”, which is the state  8  in which the magnetic tape  1  protrudes out of the flange from the state in which the magnetic tape  1  is inside the flange of the guide roller  4 , in the state in which the magnetic tape  1  is wound around the winding hub  2  by the considerable length.  
      Though the above-described defects become the problem as above, these defects cannot be eliminated by the conventional technique in the present situation. In the three references mentioned above, the sufficient measures against the above-described defects are not taken because the fine positional adjustment function of the winding hub  2  and the guide roller  4  is not included. Especially when the curve of the magnetic tape  1  is large as shown in the below, there arises the trouble that the magnetic tape  1  is displaced in the width direction and is removed from the winding hub  2 .  
      The magnetic tape  1  is manufactured by being cut into a plurality of tapes from the wide raw magnetic tape. Generally, on the raw magnetic tape, a magnetic layer is formed to be thick in the central part in the width direction of the raw magnetic tape and thin at both end portions in the width direction.  FIGS. 15A, 15B  and  15 C are conceptual diagrams showing the thickness distribution and the like of the raw magnetic tape, and  FIG. 15A  is a graph showing the result of measuring the surface profile in the width direction in the state in which the raw magnetic tape  20  is wound around the hub (winding core) in the roll shape. As in the graph, the crowing amount is as high as 874 μm in the raw magnetic tape of a predetermined width. Especially extreme portions are both end portions in the width direction in the raw material roll state. For example, the difference in the thickness (inclined thickness amount) between both sides with the width of 12.65 mm is 52 μm in the circle at the right end portion, and 70 μm in the circle at the left end portion.  
      Accordingly, even if such raw magnetic tape cut into the magnetic tapes  1  of the width of 12.65 mm, for example, the thickness distribution in the width direction remains. Thus, the magnetic tape  1  obtained from raw magnetic tape  20  at the above-described portions (both end portions in the width direction) is in the curved shape as shown in  FIG. 15B  at the left end portion and as shown in  FIG. 15C  at the right end portion. The degree of the curved shape is indicated as the value set as a curvature amount Δ with respect to the length L.  
       FIGS. 16A, 16B  and  16 C are conceptual views explaining the state in which the magnetic tape  1  having a curvature is wound up.  FIG. 16A  is a predetermined length of the magnetic tape  1  having a curvature shown in  FIG. 15B , the length of the left side edge is L 1 , and the length of the right side edge is L 2 .  FIG. 16B  is the state in which a tension force is applied to the magnetic tape  1  and the curvature is eliminated, and the length of the left and right side edges are both substantially L 2 . In this case, it is estimated that the internal stresses corresponding to the arrow lengths in  FIG. 16B  occur to the left and right side edges of the magnetic tape  1 .  
       FIG. 16C  shows the state in which the magnetic tape  1  is wound around the winding hub  2 . In this case, winding of the magnetic tape  1  is performed in the state shown in  FIG. 16B , but the internal stresses at the left and right side edges of the magnetic tape  1  differ, and therefore the force to displace in the direction of the arrow shown in  FIG. 16C  occurs so as to relieve the internal stresses. Accordingly, when the magnetic tape  1  having a curvature is wound around the winding hub  2 , the protrusion in the width direction easily occurs.  
     SUMMARY OF THE INVENTION  
      The present invention is made in view of the above circumstances, and has its object to provide a tape winding method and device and a tape winding body capable of winding up a tape at high speed and making a winding shape favorable.  
      In order to attain the above-described object, the present invention provides, in a tape winding method for winding a tape around a winding hub, a tape winding method comprising the steps of placing an axis of the winding hub to be horizontal, restraining an entry direction of the tape into the winding hub by a first roller, which is provided at an upstream side in a tape traveling direction of the winding hub so that the axis of the winding hub and an axis of the first roller are substantially parallel with each other, restraining a position of the tape in a width direction by a second roller which contacts a tape roll formed by the tape being wound around the winding hub, and is provided so that the axis of the winding hub and an axis of the second roller are substantially parallel with each other, pressing the tape at an outermost periphery of the tape roll by a third roller provided so that the axis of the winding hub and an axis of the third roller are substantially parallel with each other, restraining a position of the tape in the width direction by a fourth roller with a flange which restrains the position of the tape in the width direction while contacting the tape roll, at a downstream side in a tape traveling direction of the third roller at the outermost periphery of the tape roll, and is provided so that the axis of the winding hub and an axis of the fourth roller are substantially parallel with each other, and winding the tape with a curvature amount of 6 mm or less per a tape length of 1 m around the winding hub, and a device used for the method.  
      According to the present invention, the first to the fourth rollers are provided, and the position and the like of the tape are restrained by these rollers. Therefore, the tape with the curvature amount of 6 mm or less per the tape length of 1 m can be wound up at a high speed into a favorable winding shape.  
      The present invention also provides, in a tape winding method for winding a tape around a winding hub, a tape winding method comprising the steps of placing an axis of the winding hub to be horizontal, restraining an entry direction of the tape into the winding hub by a first roller, which is provided at an upstream side in a tape traveling direction of the winding hub so that the axis of the winding hub and an axis of the first roller are substantially parallel with each other, restraining a position of the tape in the width direction by a second roller which contacts a tape roll formed by the tape being wound around the winding hub, and is provided so that the axis of the winding hub and an axis of the second roller are substantially parallel with each other, pressing the tape at an outermost periphery of the tape roll by a third roller provided so that the axis of the winding hub and an axis of the third roller are substantially parallel with each other, and controlling a distance of a fourth roller with respect to the tape roll so that a shaft part surface of the fourth roller does not contact the tape, in which the fourth roller is a roller which restrains the position of the tape in the width direction while contacting the tape roll at a downstream side in the tape traveling direction of the third roller at the outermost periphery of the tape roll, and is provided so that the axis of the winding hub and the axis of the fourth roller are substantially parallel with each other, and the fourth roller being constructed by a shaft part and flange parts disposed at both sides of the shaft part, having taper portions in which a space between the inner surfaces of the flange parts becomes larger toward an outer diameter direction from an inner diameter direction formed in the inner surfaces of the flange parts, and a device which is used in the method.  
      According to the present invention, the winding hub is provided so that the axis becomes horizontal, the first to the fourth rollers are provided so that the winding hub and the axes of the rollers are substantially parallel with each other, and thereby winding of the tape around the tape roll is restrained. In the construction in which the position of the tape in the width direction is restrained by the fourth roller provided at the downstream side of the third roller, the fourth roller is constructed by the shaft part and the flange parts disposed at both sides of the shaft part, and the distance of the fourth roller with respect to the tape roll is controlled to support the tape while preventing the contact of the tape to the shaft part surface. Thereby, even when the curvature of the tape is large, the positional restraint of the tape in the width direction to the winding hub by the fourth roller can be reliably performed, winding of the tape can be performed at a high speed, and the tape winding which can make a favorable winding shape becomes possible.  
      In the present invention, it is preferable that the surface roughness Ra of the inner surface of the flange part of the fourth roller is 0.15 μm or less. By providing the inner surface of such surface roughness, occurrence of a flaw of the tape is restrained, and as a result, the quality of the tape winding body can be improved.  
      In the present invention, it is preferable to set a narrowest space between the inner surfaces of the flange parts of the fourth roller is set to be larger than the width of the tape by 50 μm to 500 μm. By using such a fourth roller, restraint of the position of the tape in the width direction to the winding hub can be reliably performed, and the occurrence of the flaw of the tape is restrained, as a result of which, the quality of the pancake can be improved.  
      As explained above, according to the present invention, the first to the fourth rollers are provided, and the position and the like of the tape are restrained by the rollers. Therefore, the tape with the curvature amount of 6 mm or less per the tape length of 1 m can be wound up at a high speed and can be made favorable in the winding shape.  
      According to the present invention, the position of the fourth roller is controlled so as to prevent contact of the tape to the shaft part surface of the fourth roller, and even if the curvature of the tape is large, the position of the tape in the width direction to the winding hub by the fourth roller can be reliably performed, as a result of which, winding of the tape which can provide a favorable winding shape is made possible.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a conceptual view showing a construction of a manufacturing apparatus of a pancake which is applied to the present invention;  
       FIG. 2  is a schematic diagram of a cutting device;  
       FIG. 3  is a schematic diagram of a winding device of a magnetic tape according to the present invention;  
       FIG. 4  is a side view showing a construction of a position restraining roller;  
       FIG. 5  is a side view showing a construction of an edge restraining roller;  
       FIG. 6  is a side view showing a construction of an auxiliary edge restraining roller;  
       FIG. 7  is a perspective view of a winding device of a magnetic tape;  
       FIG. 8  is a partially plan view of  FIG. 3 ;  
       FIG. 9  is a left side view of  FIG. 3 ;  
       FIG. 10  is a partially enlarged left side view of  FIG. 3 ;  
       FIGS. 11A  to  11 C are partially enlarged side views each showing positional relationship of the auxiliary edge restraining roller and a tape roll;  
       FIG. 12  is a graph showing a result of Example 1;  
       FIG. 13  is a table showing a result of Example 2;  
       FIGS. 14A  to  14 D are sectional views of pancakes each showing a state of winding fault;  
       FIGS. 15A  to  15 C are conceptual views showing thickness distribution and the like of a raw magnetic tape; and  
       FIGS. 16A  to  16 C are conceptual views each explaining a state in which a magnetic tape having a curvature is wound up. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      A preferred embodiment of a tape winding method and device and a pancake according to the present invention will be explained in detail concerning the case of winding up a magnetic tape with reference to the attached drawings, hereinafter.  FIG. 1  is a conceptual view showing a construction of a manufacturing apparatus  10  of a pancake to which the present invention is applied,  FIG. 2  is a side view of a cutting device  14 , and  FIG. 3  is a schematic diagram showing a magnetic tape winding device  15 .  
      As shown in  FIG. 1 , the pancake manufacturing apparatus  10  is mainly constructed by a feeding device  11  which feeds a raw magnetic tape  20  wound in a roll shape, a cutting device  14  which cuts the wide belt-shaped raw magnetic tape  20  into a plurality of narrow magnetic tapes  1 , and winding devices  15  which wind the magnetic tapes around the winding hubs  2 .  
      The raw magnetic tape  20  wound in the roll shape is fitted onto a hub  12  (winding core) of the feeding device  11 . The raw magnetic tape  20  is generally manufactured by forming a magnetic layer including ferromagnetic fine particles on a non-magnetic supporter by a coating method, a vacuum deposition method or the like, and performing orientation treatment, dry treatment, surface treatment and the like for the magnetic layer.  
      The cutting device  14  is the device which cuts the wide belt-shaped raw magnetic tape  20  into a plurality of magnetic tapes  1  by a pair of upper and lower rotary blades  30  and  32 , and is constructed by a plurality of rotary lower blades  30  formed in the roller shape as receiving blades, and a plurality of thin disc-shaped rotary upper blades  32  which gives the shearing force to the raw magnetic tape  20  in the space from the rotary lower blades  30  to cut the raw magnetic tape  20  as shown in  FIG. 2 .  
      The rotary lower blade  30  is fitted and fixed onto a lower shaft  34  via a spacer  36 , and the rotary upper blade  32  is fitted and fixed onto an upper shaft  38  parallel with the lower shaft  34  via a spacer  40 . The rotary lower blade  30  and the rotary upper blade  32  are disposed so that blade edge portions of the rotary upper blade  32  and the rotary lower blade  30  overlap each other. The rotary upper blade  32  is biased to the right side in the axial direction in  FIG. 2  by a spring not shown and is positioned in the state in which the blade edge portion of the rotary upper blade  32  abuts to the blade edge portion of the rotary lower blade  30 .  
      The upper shaft  38  and the lower shaft  34  are respectively connected to motors  41  and  43  capable of freely changing the respective rotational speed, so that the circumferential speeds of the rotary upper blade  32  and the rotary lower blade  30  can be changed individually.  
      In  FIG. 1 , a plurality of guide rollers  22  which form a transfer path of the raw magnetic tape  20 , and a grooved suction drum  24  which restrains the transfer speed of the raw magnetic tape  20  are provided between the feeding device  11  and the cutting device  14 . The grooved suction drum  24  is connected to a motor (not shown) of which rotational speed is freely changeable, and can optionally change the transfer speed of the raw magnetic tape  20  by rotating with the raw magnetic tape  20  sucked on a peripheral surface of the grooved suction drum  24 .  
      The rotational speed of a winding core  18  of the winding hub  2  in the winding device  15  is controlled with the circumferential speed of the grooved suction drum  24  as the reference. The device which restrains the transfer speed of the raw magnetic tape  20  is not limited to the grooved suction drum  24 , but a pinch roller which nips and transfers the raw magnetic tape  20  can be used.  
      A tension roller  28  is provided between the cutting device  14  and each of the winding hubs  2 , and the tension in the transfer direction of the raw magnetic tape  20  at the time of cutting is optionally adjusted.  
      As shown in  FIG. 3 , the winding device  15  includes the winding hub  2 , a position restraining roller  50  which is a first roller, an edge restraining roller  52  which is a second roller, a pressing roller  54  which is a third roller and an auxiliary edge restraining roller  56  which is a fourth roller.  
      The position restraining roller  50  is rotatably supported in the vicinity of a base end portion (left end portion in  FIG. 3 ) of a lower arm  60  via a bearing  51 . The edge restraining roller  52  and the pressing roller  54  are rotatably supported via a support plate  58  provided in the vicinity of a tip end portion (right end portion in  FIG. 3 ) of the first arm  60 . The auxiliary edge restraining roller  56  is rotatably supported in the vicinity of a tip end portion (left end portion in  FIG. 3 ) of a support arm  62 .  
      The winding hub  2  is provided at an apparatus body (building frame) not shown so that the axis is horizontal, and is rotationally driven in the counterclockwise direction as shown by the arrow. A tape roll  1 ′ is formed by winding the magnetic tape  1  around this winding hub  2 . The tape roll  1 ′ with the magnetic tape  1  of the predetermined length wound around therearound becomes the pancake as the product.  
      The position restraining roller  50  which is the first roller is a flanged roller provided at the lower arm  60  at the upstream side in the tape traveling direction of the winding hub  2  so that the axis of the roller  50  is substantially parallel with the axis of the winding hub  2 . The shape of the position restraining roller  50  is the roller with flanges  50 B, and a surface of a roller  50 A is formed by being crowned as shown in  FIG. 4 . The position restraining roller  50  is a solid product of stainless steel. The width of the roller  50 A is formed to be substantially the same as the width of the magnetic tape  1 . The flanges  50 B and  50 B have taper surfaces  50 C and  50 C inclined so that the space is larger toward the outer diameter portion from the inner diameter portion in the inner surface. This position restraining roller  50  restrains the entry direction of the magnetic tape  1  to the tape roll  1 ′.  
      The edge restraining roller  52  which is the second roller is the flanged roller which contacts the tape roll  1 ′ and is provided at the lower arm  60  so that the axis of the roller  52  is substantially parallel with the axis of the winding hub  2 .  FIG. 5  is a side view of the edge restraining roller  52 . Flanges  52 B and  52 B are provided at both sides of a cylindrical roller  52 A, and the roller  52 A and the flanges  52 B and  52 B are connected via roller bearings  52 D and  52 D placed inside the roller  52 A. Accordingly, the flanges  52 B and  52 B are rotatable with respect to the roller  52 A.  
      The width of the roller  52 A is formed to be a little smaller than the width of the magnetic tape  1 . The roller  52 A is formed of polyacetal, but may be formed of various kinds of resins other than polyacetal, for example, various kinds of engineering plastics. An inner surface of the flange  52 B is formed to be taper surfaces  52 C and  52 C which incline so that a space becomes larger from an inner diameter portion which is the same as the outer diameter of the roller  52 A to an outer diameter portion. The flange  52 B is formed of stainless steel. It is preferable that surface roughness Ra of the taper surface  52 C of the flange  52 B is 0.15 μm or less. By providing such a smooth taper surface  52 C, a defect can be prevented from occurring to an edge portion of the magnetic tape  1 .  
      The edge restraining roller  52  restrains the position of the magnetic tape  1  in the width direction. Namely, the edge of the magnetic tape  1  abuts to the taper surface  52 C, and thereby the position of the magnetic tape  1  in the width direction is restrained. In order to make the winding shape favorable by favorably restraining the position of the magnetic tape  1  in the width direction, it is preferable to set an inclination angle θc of the taper surface  52 C within the range of 2 degrees to 15 degrees. It is also preferable to set the width of the roller  52 A in the range of 95% to 99% of the width of the magnetic tape  1 .  
      The pressing roller  54  which is the third roller is a columnar roller which presses the magnetic tape  1  at an outermost periphery of the tape roll  1 ′ and is provided at the lower arm  60  so that the axis of the roller  54  is substantially parallel with the winding hub  2 . The pressing roller  54  is formed of urethane rubber, but may be formed of various kinds of synthetic rubber other than urethane rubber, such as, for example, silicon rubber, fluororubber, and chloroprene rubber. The pressing roller  54  is provided to push out air between the magnetic tape  1  and the tape roll  1 ′ by pressing the magnetic tape  1  and make the winding shape favorable. It is preferable that the width of the pressing roller  54  is a little smaller than the width of the magnetic tape  1 . If the width of the pressing roller  54  is larger than the width of the magnetic tape  1 , the surface of the pressing roller  54  is deformed into a recessed shape, and tends to cause a winding defect of the magnetic tape  1 .  
      The edge restraining roller  52  and the pressing roller  54  are rotatably supported at the support plate  58 . The support plate  58  is rotatably supported at the lower arm  60  with a support point  60 A provided in the vicinity of the tip end portion of the lower arm  60  as a center.  
      The lower arm  60  is rotatably supported at the apparatus body (building frame) not shown with a support point  60 B provided at the base end portion as a center. The lower arm  60  is biased to the tape roll  1 ′ side (in the counterclockwise direction) by a biasing device  61  constituted of a spring or the like. Thereby, the edge restraining roller  52  and the pressing roller  54  are pressed to the tape roll  1 ′ with predetermined pressure. It is preferable to set this pressing force at a predetermined force by which the edge restraining roller  52  and the pressing roller  54  are prevented from being separated from the tape roll  1 ′ by the rotation of the tape roll  1 ′. This pressing force may take an appropriate value in accordance with the width of the magnetic tape  1 , the rotational frequency of the tape roll  1 ′, the quality of the material of the magnetic tape  1  and the like. As the biasing device  61 , a known device such as an air cylinder can be adopted.  
      The auxiliary edge restraining roller  56  which is the fourth roller is provided at the opposite side from the edge restraining roller  52  and the pressing roller  54  with the tape roll  1 ′ therebetween. Namely, in the downstream side of the pressing roller  54  in the outermost periphery of the tape roll  1 ′, the auxiliary edge restraining roller  56  is provided so that the auxiliary edge restraining roller  56  is in contact with the tape roll  1 ′ and an axis of the auxiliary edge restraining roller  56  is substantially parallel with that of the winding hub  2 .  
       FIG. 6  is a side view of the auxiliary edge restraining roller  56 . In this auxiliary edge restraining roller  56 , flanges  56 B and  56 B are provided at both sides of a cylindrical roller  56 A, and the roller  56 A and the flanges  56 B and  56 B are connected via roller bearings  56 E and  56 E placed inside the roller  56 A. Accordingly, the flanges  56 B and  56 B are rotatable with respect to the roller  56 A.  
      Since the auxiliary edge restraining roller  56  supports the tape roll  1 ′ and gently restrains the width of the tape roll  1 ′ with a predetermined looseness (gap, play), it is preferable to set the width of the roller  56 A to be a little larger than the width of the magnetic tape  1 . The roller  56 A is formed of polyacetal, but it may be formed of various kinds of resins other than polyacetal, for example, various kinds of engineering plastics. The inner surface of the flange  56 B is formed to be straight inner side surfaces  56 D and  56 D, and the outer diameter side from the inner side surfaces  56 D and  56 D is formed to be taper surfaces  56 C and  56 C which are inclined so that the space is larger toward the outer diameter part. The flange  56 B is formed of stainless steel. As shown in  FIG. 3 , the auxiliary edge restraining roller  56  is rotatably supported at the support arm  62  with a support point  62 A provided in the vicinity of the tip end portion of the support arm  62  as a center.  
      The support arm  62  is rotatably supported in a substantially horizontal direction by the upper arm  66  via a roller bearing which is a rotational support point  64 , in a base end portion  62 B. Further, the upper arm  66  is rotatably supported at the apparatus body (building frame) not shown in a substantially perpendicular direction in a base end portion  66 A. The upper arm  66  is biased to the tape roll  1 ′ side (in the counterclockwise direction) by a biasing device  66 B. Thereby, the auxiliary edge restraining roller  56  is pressed to the tape roll  1 ′ at predetermined pressure.  
      As the biasing device  66 B, the combination of a ball screw  70  and a servo motor  72  is adopted. The servo motor  72  is rotatably supported at the building frame, and a screw portion  70 A of the ball screw  70  is fixed to the rotary shaft of the servo motor  72 . A ball head  70 B (corresponding to a nut portion) of the ball screw  70  is firmly fixed to the upper arm  66 . When the servo motor  72  is rotationally driven in this state, the ball head  70 B moves in the substantially vertical direction, and the upper arm  66  rotates in the substantially vertical direction. The details of the positional control of the upper arm  66  by this biasing device  66 B will be described later.  
      As the biasing device  66 B, a known device such as a coil spring can be adopted other than the above. The pressing force by the auxiliary edge restraining roller  56  can take an appropriate value in accordance with the width of the magnetic tape  1 , the rotational frequency of the tape roll  1 ′, the quality of material of the magnetic tape  1  and the like as in the lower arm  60 , but it is preferable that the pressing force (touch pressure) at which the auxiliary edge restraining roller  56  presses the tape roll  1 ′ is adjustable to be variable in the range of 0.2 to 2.0 N.  
      Next, the function of the auxiliary edge restraining roller  56  will be explained. As explained by  FIG. 15  and  FIG. 16 , when the magnetic tape  1  having a curvature is wound around the tape roll  1 ′ (winding hub  2 ), protrusion in the width direction easily occurs. The auxiliary edge restraining roller  56  is provided to prevent such protrusion in the width direction.  
       FIG. 7  is a perspective view of the magnetic tape winding device  15 . In  FIG. 7 , the entry direction of the magnetic tape  1  to the tape roll  1 ′ is restrained by the position restraining roller  50 , the position of the magnetic tape  1  in the width direction is restrained by the edge restraining roller  52 , and the air between the magnetic tape  1  and the tape roll  1 ′ is pushed out by the pressing roller  54 , whereby the winding shape is favorably restrained. However, in the case of the magnetic tape  1  with a large curvature, so-called protrusion D occurs, which is the magnetic tape  1  displacing in the width direction from the tape roll  1 ′ at the downstream of the pressing roller  54 . In this case, the width of the tape roll  1 ′ is also restrained by the auxiliary edge restraining roller  56 , and the protrusion D in the width direction is corrected, whereby a favorable winding shape can be obtained.  
      Next, the construction of the support arm  62  and the like which support the auxiliary edge restraining roller  56  will be explained.  FIG. 8  is a partially plan view of  FIG. 3 ,  FIG. 9  is a left side view of  FIG. 3 , and  FIG. 10  is a partially enlarged left side view of  FIG. 3 . In  FIG. 10 , only the auxiliary edge restraining roller  56  and its periphery are shown.  
      In  FIG. 8 , the support arm  62  is rotatably supported in the substantially horizontal direction by the upper arm  66  (see  FIG. 3 ) via the roll bearing which is the rotational support point  64 , at the base end portion  62 B.  FIG. 9  shows the state in which a track center  52 K of the edge restraining roller  52  which presses the lower side of the tape roll  1 ′, and a track center  56 K of the auxiliary edge restraining roller  56 , which presses the upper side of the tape roll  1 ′ are displaced from each other.  
      Even in the state in which the track centers are displaced from each other by K, the support arm  62  rotates in the direction of the arrow A, or in the direction of the arrow B in  FIG. 8  and  FIG. 9 , and thereby, the auxiliary edge restraining roller  56  moves to an appropriate position, whereby the protrusion D in the width direction is eliminated. Especially because the support arm  62  is supported rotatably in the substantially horizontal direction with the rotational support point  64  provided at the downstream side in the tape traveling direction as a center, the support arm  62  follows the position of the traveling magnetic tape  1 , and is automatically settled down at the position where the load is least exerted, and thereby the protrusion D in the width direction can be eliminated. The aforementioned rotational support point  64  may have the construction except for a roll bearing if only the above-described function can be exhibited.  
      In the construction in which the positional control of the magnetic tape  1  in the width direction by the auxiliary edge restraining roller  56  explained above, it is preferable that the moving amount of the support arm  62  in the direction of the arrow A or in the direction of the arrow B is in the range of ±0.5 to 2.0 mm, for example, and it is preferable that the displacement amount K of the track centers is within the range of ±0.15 mm, for example, and it is preferable that the length  62 L of the support arm  62  (the distance from the axis of the auxiliary edge restraining roller  56  to the axis of the rotational support point  64 ) is in the range of 20 to 150 mm, for example.  
      Next, a construction in which the vertical position of the auxiliary edge restraining roller  56  is controlled by the support arm  62  and the upper arm  66  will be explained.  FIGS. 11A, 11B  and  11 C are partially enlarged side views showing positional relationship of the auxiliary edge restraining roller  56  and the tape roll  1 ′. In the drawings,  FIG. 11A  shows a state of start of winding of the magnetic tape  1 ,  11 B shows the state in which winding of the magnetic tape  1  proceeds, and winding thickness of the magnetic tape  1  becomes such a value as is called “loading completion thickness d”, and  FIG. 11C  shows the state in which winding of the magnetic tape  1  further proceeds.  
      In the construction in  FIGS. 11A, 11B  and  11 C, it is preferable to set a space between the narrowest portions of the inner surfaces of the flanges  56 B of the auxiliary edge restraining roller  56  to be larger than the width of the magnetic tape  1  by 50 to 500 μm. By using such an auxiliary edge restraining roller  56 , the position restraint in the width direction of the magnetic tape  1  to the winding hub  2  can be reliably performed, occurrence of a flaw of the magnetic tape  1  is restrained, and as a result, the quality of the pancake can be improved.  
      Namely, as shown in  FIG. 11A , a narrowest space between inner surfaces of the flanges  56 B (hereinafter, called “restraint width”) d 1  is set to be larger than a width d 0  of the magnetic tape  1  by 50 to 500 μm. Specifically, when the width d 0  of the magnetic tape  1  is 12.650 mm, a width d 2  of a shaft part  56 A is set to be 12.700 mm, and the restraint width d 1  is set to be 12.700 to 13.150 mm.  
      In the state from  FIG. 11A  to  FIG. 11B , the flanges  56 B and  56 B of the auxiliary edge restraining roller  56  are freely running in contact with the winding hub  2 . The position of the edge portion of the magnetic tape  1  is restrained by the inner surfaces of the flanges  56 B and  56 B. In this state, the magnetic tape  1  is not in contact with the shaft part  56 A of the auxiliary edge restraining roller  56 . In the state shown in  FIG. 11B , a distance between the surface of the magnetic tape  1  at the outermost periphery of the tape roll  1 ′ and the surface of the shaft part  56 A of the auxiliary edge restraining roller  56  is g, and the winding thickness of the magnetic tape  1  is at the value called “loading completion thickness d”.  
      From the state shown in  FIG. 11B , the position of the auxiliary edge restraining roller  56  in the vertical direction is controlled so that the distance g is kept at a fixed value. Namely, as shown in  FIG. 11C , in the state in which winding of the magnetic tape  1  further advances, the magnetic tape  1  and the shaft part  56 A of the auxiliary edge restraining roller  56  are not in contact with each other.  
      As the construction which enables such an operation, a device which detects the outer diameter of the tape roll  1 ′ and a device which controls a position of the auxiliary edge restraining roller  56  are needed. As the device which detects the outer diameter of the tape roll  1 ′, a device which detects the rotational frequency of the winding hub  2  (tachometer or the like) is adopted (not shown). Namely, the traveling speed of the magnetic tape  1  is always constant, and the rotational frequency of the winding hub  2  changes in accordance with the outer diameter of the tape roll  1 ′. Accordingly, by detecting the rotational frequency of the winding hub  2 , the outer diameter of the tape roll  1 ′ can be easily calculated.  
      Meanwhile, as the device which controls the position of the auxiliary edge restraining roller  56 , the combination of the ball screw  70  and the servo motor  72 , which is already described in accordance with  FIG. 3 , is adopted. Namely, the servo motor  72  is rotationally driven to control the position of the auxiliary edge restraining roller  56  in the vertical direction so that the distance g shown in  FIGS. 11B and 11C  is kept at a fixed value from the calculated outer diameter of the tape roll  1 ′. Such a control can be performed by a known device such as a microcomputer.  
      As the device which detects the outer diameter of the tape roll  1 ′, a construction other than the above, for example, the construction in which an air cylinder with a positional sensor is used as the biasing device of the lower arm  60  is used, and the outer diameter of the tape roll  1 ′ is obtained by detecting the rotating position of the lower arm  60  can be adopted. A construction in which a position sensor is attached to the auxiliary edge restraining roller  56  or the support arm  62  without obtaining the outer diameter of the tape roll  1 ′, and the distance g shown in  FIGS. 11B and 11C  is directly obtained can be adopted. Similarly, various kinds of known devices can be adopted as the device which controls the position of the auxiliary edge restraining roller  56 .  
      Next, an operation of the manufacturing apparatus  10  of a pancake as constructed as above will be explained. First, in  FIG. 1 , the roll-shaped raw magnetic tape  20  wound around the hub  12  of the feeding device  11  is continuously drawn from the hub  12 , and transferred to the cutting device  14 . Subsequently, the raw magnetic tape  20  is cut into a plurality of magnetic tapes  1  by the cutting device  14 , and transferred to the winding device  15 , and wound around the winding hub  2 . Thereby, for example, the raw magnetic tape  20  is cut into 100 to 500, and magnetic tapes  1  each of a specified width dimension (for example, 12.65 mm, 25.4 mm, 3.81 mm and the like) are manufactured.  
      In  FIG. 3 , the entry direction of the magnetic tape  1  into the tape roll  1 ′ is restrained by the position restraining roller  50  in the winding device  15 . Next, the position of the magnetic tape  1  in the width direction is restrained by the edge restraining roller  52 . Next, air between the magnetic tape  1  and the tape roll  1 ′ is pushed out by the pressing roller  54 , and the winding shape is favorably restrained. The tape roll  1 ′ is supported by the auxiliary edge restraining roller  56  at the downstream by about  180  degrees of the tape roll  1 ′, and the width of the tape roll  1 ′ is gently restrained with predetermined looseness.  
      In this case, even if the track center  52 K of the edge restraining roller  52  and the track center  56 K of the auxiliary edge restraining roller  56  are in the state displaced by K as shown in  FIG. 9 , the auxiliary edge restraining roller  56  moves to a proper position as a result that the support arm  62  rotates, and thereby, a winding fault in which the magnetic tape  1  cannot be restrained by the flanges of the roller at the time of start of winding hardly occurs.  
      As the winding of the magnetic tape  1  advances and the outer diameter of the tape roll  1 ′ increases in this winding device  15 , the lower arm  60  rotates around the support point  60 B in the arrow direction in  FIG. 3 , and the edge restraining roller  52  and the pressing roller  54  keep pressing the tape roll  1 ′ with a proper pressing force by the rotation of the lower arm  60  and very small rotation of the support plate  58  around the support point  60 A.  
      Similarly, as the outer diameter of the tape roll  1 ′ increases, the upper arm  66  rotates around the support point  66 A in the arrow direction in  FIG. 3 , and the auxiliary edge restraining roller  56  keeps pressing the tape roll  1 ′ with a proper pressing force by the rotation of the upper arm  66 .  
      More specifically, in the state from  FIG. 11A  of the start of winding of the magnetic tape  1  to  FIG. 11B , there is no movement of the auxiliary edge restraining roller  56  in the vertical direction, as shown in  FIGS. 11A  to  11 C already mentioned. The position of the edge portion of the magnetic tape  1  is restrained by the inner surfaces of the flanges  56 B and  56 B. In this state, the magnetic tape  1  is not in contact with the shaft part  56 A of the auxiliary edge restraining roller  56 .  
      In the state shown in  FIG. 11B , the distance between the surface of the magnetic tape  1  at the outermost periphery of the tape roller  1 ′ and the surface of the shaft part  56 A of the auxiliary edge restraining roller  56  is g. From this state, the position of the auxiliary edge restraining roller  56  in the vertical direction is controlled so that the distance g is kept at a fixed value by the control device already described. As shown in  FIG. 11C , the magnetic tape  1  and the shaft part  56 A of the auxiliary edge restraining roller  56  are not in contact with each other even in the state in which the winding of the magnetic tape  1  further advances. The position of the edge portion of the magnetic tape  1  is restrained by the inner surfaces of the flanges  56 B and  56 B. Thereby, the position restraint of the magnetic tape  1  in the width direction to the winding hub  2  can be reliably performed, and occurrence of a flaw of the magnetic tape  1  is restrained, as a result of which, the quality of the pancake can be improved.  
      The embodiment of the magnetic tape winding method and device and a pancake according to the present invention are explained thus far, but the present invention is not limited to the above-described embodiment, and various kinds of modes can be adopted.  
      For example, the magnetic tape is wound by the winding device  15  from the raw magnetic tape  20  via the cutting device  14  in this embodiment, but the mode in which slit treatment is previously performed and the magnetic tape is fed out in the state in which it already becomes the magnetic tape  1  of a predetermined width may be adopted.  
      The construction of the winding device  15  is not limited to this embodiment, but various kinds of constructions may be adopted. For example, the edge restraining roller  52  and the pressing roller  54  are supported by the plate  58  in this embodiment, but the construction in which they are individually supported by the lower arm  60  may be adopted.  
      Further, the example of this embodiment has the construction in which the upper arm  66  is rotated around the support point  66 A in the vertical direction, but when there is the strong necessity of keeping the support arm  62  in the horizontal state, for example, the construction in which the upper arm is made a pantagraph mechanism and the support arm  62  is supported at the tip end portion rotatably in the horizontal direction can be adopted.  
     EXAMPLES  
     Example 1  
      The winding test of the magnetic tape  1  was performed by using the winding device  15  of the construction shown in  FIG. 3 . As the magnetic tape  1 , the mode in which the magnetic tape was fed in the state in which it was previously subjected to slit treatment and already became the magnetic tape  1  of the predetermined width was adopted. This magnetic tape  1  was 12.65 mm wide and 8.9 μm thick and was of a polyester base. As a pancake, the winding length of the magnetic tape  1  of 14,000 m is set. As the magnetic tape  1 , those with various kinds of curvature amounts were prepared. As the curvature amount Δ, 0 to 6 mm were adopted with respect to L=1 m shown in  FIG. 15B  and  FIG. 15C .  
      In the example, as the construction and the positional control in the vertical direction of the auxiliary edge restraining roller  56 , the method explained in the “DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT” was adopted as it is.  
      Meanwhile, as a comparison example, the construction in which only the positional control method in the vertical direction of the auxiliary edge restraining roller  56  was made different was adopted. Namely, in the comparison example, the pressing device by the coil spring was used as the biasing device  66 B of the upper arm  66  in place of the combination of the ball spring  70  and the servo motor  72 . Accordingly, in the comparison example, the auxiliary edge restraining roller  56  was pressed by the tape roll  1 ′ with predetermined pressure, and the positional control of the auxiliary edge restraining roller  56  in the vertical direction was not made, whereby the magnetic tape  1  is in contact with the shaft part  56 A of the auxiliary edge restraining roller  56 .  
      In the example and the comparative example, the auxiliary edge restraining roller  56  having the construction explained according to  FIG. 5  was adopted. The outer diameter of the roller  56 A was 16 mm, the outer diameter of the straight portion  56 D of the flange  52 B was 26 mm, and the outermost diameter of the taper surface  56 C was 30 mm.  
      The magnetic tape  1  was wound around the winding hub  2  with the traveling speed of the magnetic tape  1  set at 600 m/min, and the winding length where the winding defect did not occur was recorded as “winding OK length”.  FIG. 12  is the graph showing the winding results of the example and the comparative example, the vertical axis is the winding OK length (unit: m) and the horizontal axis is a curvature amount A (unit: mm) of the magnetic tape  1 .  
      In the example, in all the conditions of the curvature amounts Δ of 0 to 6 mm, the winding OK length was 14,000 m, and good products as the pancakes was able to be obtained in all the conditions.  
      On the other hand, in the comparative example, the winding OK length was 14,000 m in the condition of the curvature amounts Δ of 0 to 2 mm, but after the curvature amount Δ exceeded 2 mm, the winding OK length reduced extremely.  
      From the results in  FIG. 12  shown above, it was confirmed that winding of the magnetic tape in the favorable winding shape at high speed was made possible by performing the positional control of the auxiliary edge restraining roller  56  in the vertical direction.  
     Example 2  
      The winding test of the magnetic tape  1  was performed by using the winding device  15  of the construction shown in  FIG. 3 . As the magnetic tape  1 , the mode in which the magnetic tape was fed out from the state in which the magnetic tape was previously subjected to slit treatment and already became the magnetic tape  1  of the predetermined width. The magnetic tape  1  was of a polyester base of the width of 12.65 mm and the thickness of 8.9 μm. As the pancake, the winding length of the magnetic tape  1  was set at 14,000 m.  
      As in the example 1, the auxiliary edge restraining roller  56  having the construction explained according to  FIG. 5  was adopted. The outer diameter of the roller  56 A was 16 mm, the outer diameter of the straight portion  56 D of the flange  52 B was 26 mm, and the outermost diameter of the taper surface  56 C was 30 mm.  
      Seven kinds of the auxiliary edge restraining rollers  56  the surface roughness Ra of which inner surfaces of the flanges  52 B, namely the straight portions  52 D and the taper surfaces  52 C was changed from 0.05 to 0.25 μm were prepared, and were sequentially mounted to the winding device  15  by being replaced with one another, and the quality of the pancake in the surface roughness Ra was evaluated.  
      As the method for controlling the surface roughness Ra of the inner surface of the flange  52 B, the surface roughness Ra was controlled by changing the buff condition (count or the like of the polishing cloth) of the flange  52 B.  
      The evaluation result is shown in the table in  FIG. 13 . In the table, “abrasion pattern” which is the evaluation item is the presence and absence of the abrasion pattern which was recognized when the side surface of the pancake was visually observed. The case in which the abrasion pattern was not recognized was determined as the circle, and the case in which the abrasion pattern was recognized was determined as the cross. When the abrasion pattern was observed by the microscope, it was recognized that the damage occurred at the edge portion.  
      The “Edge damage” which is the evaluation item in the table in  FIG. 13  is whether the problem such as a dropout occurs or not when the pancake was attached to the tape deck, and the case in which the problem did not occur was determined as the circle, and the case in which the problem occurred was determined as the cross.  
      According to the table in  FIG. 13 , in the condition in which the surface roughness Ra was 0.15 μm or less, both the items of the abrasion pattern and the edge damage were the determined as circles. On the other hand, in the condition in which the surface roughness exceeds 0.15 μm, neither of the abrasion pattern nor the edge damage was determined as a cross. Therefore, it can be said as preferable to control the surface roughness Ra of the inner surface of the flange  52 B to be 0.15 μm or less.