Patent Publication Number: US-2010108733-A1

Title: Web conveyance controlling method, web slip amount measuring means, and web conveyance controlling device

Description:
TECHNICAL FIELD 
     The present invention relates to a web conveying control method, a web slip amount measuring means, and a web conveying control device, more particularly to a technique of controlling the slip of the web with respect to the roll arranged in the conveying line for continuously conveying the web. 
     BACKGROUND ART 
     Conventional conveying line continuously conveys a long work (“web”) such as electrode members used for secondary batteries and the control method thereof is well known. In such conveying line, various rolls disposed therein are adjusted for a feedback control of the conveying speed and tension of the web (“control of the conveying speed and tension of the web”), so the web is stably conveyed. 
     In the conveying line, “Disturbance” such as misalignment of the rolls in the line and failure to control the speed causes the lateral shift of the web (in other words, the web slides to the wide direction to the conveying line). Especially, in order to reduce the product costs, high speed handling of the web is required, however, when the conveying speed becomes higher, the web is easy to slip with respect to the rolls. 
     In view of preventing the web slip with respect to the roll, JP-2000-143053 A discloses the technique, as to the tension of the web continuously conveyed, that the tension of the web from the dancer roll disposed in the bridle section is adjusted to be the tension where the tension cut ratio of the bridle roll in the bridle section is the same on the basis of the tension of the web in the adjacent sections. 
     As disclosed in JP-2000-143053 A, the conventional control method is the method for preventing the slip of the web by means of controlling the tension of the web, however, in the condition that the “disturbance” changes the conveying speed, the slip of the web is not able to be prevented accurately with the tension control. Especially, the lateral shift of the web with regard to the roll is susceptible to the conveying speed and tension of the web, so that when the “disturbance” changes the conveying speed, the prevention of the slip by means of the tension control fails to keep the performance of controlling the lateral position of the web. 
     Generally, the conveying line has guide rolls for controlling the lateral position of the web, and the guide rolls control the lateral position of the web with high-accuracy, so keeping the quality of the web during the conveyance. The guide rolls are disposed at the midway of the line, adopted as the center-pivot type or end-pivot type depending on the disposed position, and the relative angles to the line are changeable pivoting around the axis thereof. Using such the guide rolls, when the serpentine web is conveyed to the guide rolls, the guide rolls changes the relative angles to the line such that the lateral shift caused by the “disturbance” is canceled and the error is corrected. 
     Unfortunately, in the technique of using the guide rolls for controlling the lateral position of the web, when the slip occurs, the change of the relative angle of the guide roll does not prevent the slip, so the control for the lateral position may fail. Further, the conventional method of controlling the web-conveyance fails to control the slip when the “disturbance” changes the conveying speed, so that, in using the guide rolls for controlling the lateral position of the web, there occurs buckles on the web due to the high tension of the web, or there occurs slipping of the web due to the low tension of the web. 
     The present invention aims to provide a web conveying control method, a web slip amount measuring means, and a web conveying control device, in which the slip of the web is accurately controlled, thereby reducing the lateral shift of the web. 
     DISCLOSURE OF INVENTION 
     The problems to be solved by the present invention is described above, the means of solving the problems will be followed. 
     The first aspect of the present invention is a web conveying control method of controlling a slip of the web with respect to a roll arranged in a conveying line for conveying the web continuously. The method includes: a step of measuring a conveying speed and tension of the web during conveying; a step of calculating a slip amount of the web with respect to the roll using the measured conveying speed and tension of the web; and a step of controlling the conveying speed and/or the tension of the web such that the slip amount becomes a target slip amount set in advance. 
     Preferably, the step of controlling includes: deciding whether a difference between the calculated slip amount and the target slip amount is within a preset threshold range; calculating, when deciding that the difference goes beyond the threshold range, an ideal conveying speed or an ideal tension of the web with regard to the target slip amount in case that the conveying speed or tension is constant; and controlling the conveying speed and/or the tension of the web so as to be the calculated ideal conveying speed or ideal tension. 
     The second aspect of the present invention is a web slip amount measuring method, which includes: a step of measuring a rotational speed of a guide roll; and a step of measuring the slip amount of the web with respect to the guide roll on the basis of a difference between the measured conveying speed of the web and the measured rotational speed of the guide roll. 
     The alternative embodiment of the second aspect is a web slip amount measuring method, which includes: a step of measuring a rotational speed of a drive roll which conveys the web; a step of measuring a rotational speed of a guide roll; and a step of measuring the slip amount of the web with respect to the guide roll on the basis of a difference between the measured rotational speed of the drive roll and the measured rotational speed of the guide roll. 
     The other embodiment of the second aspect is a web slip amount measuring method, which includes: a step of detecting a shifting amount of the web from a surface of the roll; and a step of measuring the slip amount of the web with respect to the roll on the basis of the shifting amount. 
     The third aspect of the present invention is a web conveying control device for controlling a slip of the web with respect to a roll arranged in a conveying line for conveying the web continuously. The device includes: means of measuring a conveying speed and tension of the web during conveying; means of calculating a slip amount of the web with respect to the roll using the measured conveying speed and tension of the web; and means of controlling the conveying speed and/or the tension of the web such that the slip amount becomes a target slip amount set in advance. 
     Preferably, the means of controlling includes: means of deciding whether a difference between the calculated slip amount and the target slip amount is within a preset threshold range; and means of calculating, when deciding that the difference goes beyond the threshold range, an ideal conveying speed or an ideal tension of the web with regard to the target slip amount in case that the conveying speed or tension is constant, wherein the conveying speed and/or the tension of the web is controlled so as to be the calculated ideal conveying speed or ideal tension. 
     The advantageous embodiment of the third aspect includes: means of measuring a rotational speed of a guide roll; and means of measuring the slip amount of the web with respect to the guide roll on the basis of a difference between the measured conveying speed of the web and the measured rotational speed of the guide roll. 
     The alternative embodiment of the third aspect includes: means of measuring a rotational speed of a drive roll which conveys the web; means of measuring a rotational speed of a guide roll; and means of measuring the slip amount of the web with respect to the guide roll on the basis of a difference between the measured rotational speed of the drive roll and the measured rotational speed of the guide roll. 
     The other embodiment of the third aspect includes: means of detecting a shifting amount of the web from a surface of the roll; and means of measuring the slip amount of the web with respect to the roll on the basis of the shifting amount. 
     According to the present invention, in controlling the web-conveyance, the slip of the web is accurately controlled, thereby lowering the lateral shift of the web. In other words, in conveying control for the web, if the “disturbance” changes the conveying speed and tension of the web, the slip of the web is controlled with high accuracy; as a result, the shift (lateral shift) of the web with respect to the roll can be lowered. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a side view illustrating a conveying line provided with a conveying control device as a first embodiment of the present invention. 
         FIG. 2  is a block diagram showing the conveying control device. 
         FIG. 3  is a map drawing a correlation table (tension versus conveying speed). 
         FIG. 4  is a flowchart showing a conveying control method of the conveying control device. 
         FIG. 5  is a side view illustrating a conveying line provided with a conveying control device as a second embodiment of the present invention. 
         FIG. 6  is a side view illustrating a conveying line provided with a conveying control device as a third embodiment of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     First of all, the whole structure of a conveying line  1  for a web  2  will be described below. 
     As shown in  FIG. 1 , the line  1  contains a start roll  10  arranged at the upstream side and a feed roll  11  arranged at the downstream side, and from the roll  10  to the roll  11 , there are guide rolls  12 ,  13 ,  14 ,  15 , and a dancer roll  16  arranged in turn. The web  2  is conveyed with being strained at these guide rolls at certain angles. 
     The rolls  10 ,  11  have nip rolls  17 ,  18  disposed thereon, respectively. The rolls  17 ,  18  are contacted and pressed to the rolls  10 ,  11  by air-cylinders (not shown) or the like, for preventing slips of the web  2  on the rolls  10 ,  11 . The web  2  is fed synchronously with the rolls  10 ,  11 . 
     The start roll  10  is connected to a motor  10   a,  and the motor  10   a  is connected to a control unit  30 . The feed roll  11  is connected to a motor  11   a,  which is connected to the control unit  30 . 
     Each of the bodies of the guide rolls  12 ,  13 ,  14 ,  15  is pivoted on a rotation axis, thereby rotating in cooperated with the web  2  conveyed along the line  1 . The roll  14  of these guide rolls  12  to  15  is disposed at the middle of the line  1 , in which a relative angle of a pivot axis (not shown) to the line  1  can change (“end-pivot type”). According to this roll  14 , when the web  2  is conveyed serpentinely to the roll  14 , the relative angle is changed so as to counteract the lateral shift of the web  2 , thereby controlling the lateral position of the web  2  and correcting the error. 
     The dancer roll  16  is disposed between a pair of fixed roll  19 ,  19  and pivots on one end of an arm  16   a,  which is swingably supported on a support point  16   b  by the other end thereof. The arm  16   a  is connected to a motor  16   c,  and the motor  16   c  is connected to the control unit  30  for swing-control. 
     In the conveying line  1 , the web  2  is conveyed through the start roll  10  pressed by the nip roll  17 , the guide rolls  12  to  15 , the fixed roll  19 , the dancer roll  16 , the fixed roll  19 , and the feed roll  11  pressed by the nip roll  18  in sequence. 
     Next, a conveying control device  3  for the web  2  is described below as a first embodiment. 
     The control device  3  aims to stably convey the web  2  along the line  1 , controls the conveying speed of the web  2  by adjusting the drive of rolls  10 ,  11  and controls the tension of the web  2  with respect to the dancer roller  16  by swinging the arm  16   a.  Specifically, the control method of the control device  3  is based on the slip amount of the web  2  to the guide roll  14  in the line  1 , the conveying speed and tension are controlled to adjust the slip of the web  2  with respect to the roll  14  and to reduce the shift amount in the lateral direction. 
     As shown in  FIG. 1 , the control device  3  includes the control unit  30  as a means for controlling the motor  10   a  and the like to control the conveying speed and tension of the web  2 , an encoder  31  as a means for measuring the rotational speed of the start roll  10 , which conveys the web  2 , a speedometer  32  as a means for measuring the conveying speed of the web  2 , a tension meter  33  for measuring the tension of the web  2 , an encoder  34  as a means for measuring the rotational speed of the guide roll  14 , and a guide controller  36  for controlling the relative angle of the roll  14  to the line  1 . The encoder  31 , speedometer  32 , tension meter  33 , encoder  34  and controller  36  are both connected to the control unit  30 . 
     The control unit  30  receives the signals from the encoder  31  and the like, and is composed of a CPU for processing, a memory for storing the processing program, an interface for input the operations for the CPU, a display such as CRT or LCD. 
     As shown in  FIG. 2 , the control unit  30  includes a conveying speed control unit  30   a  for controlling the conveying speed of the web  2 , a tension control unit  30   b  for controlling the tension of the web  2 , a slip amount measuring unit  30   c  as a means for measuring the slip amount of the web  2 , a slip amount calculating unit  30   d  as a means for calculating the real slip amount of the web using the conveying speed and tension of the web  2 , a deciding unit  30   e  as a means for deciding whether the difference is within the preset threshold range between the real slip amount of the web  2  calculated by the unit  30   d  and the target slip amount set in advance, and a calculating unit  30   f  as a means for calculating the ideal tension of the web  2  to the target slip amount in the case that the conveying speed of the web  2  is constant. 
     The conveying speed control unit  30   a  adjusts the motors  10   a,    11   a,  connected to the control unit  30 , to control the rotational speed of the rolls  10 ,  11  to the target speed (target number of revolution) set in advance. Especially, as to the start roll  10 , the encoder  31  is disposed at the drive shaft of the roll and detects the rotational speed (number of revolution) of the roll  10 . The detected signal of the encoder  31  is transmitted to the unit  30 , the unit  30   a  adjusts the motor  10   a  such that the roll  10  rotates at the target speed on the basis of the received signal. In the embodiment, the unit  30   a  also adjusts the roll  11  to rotate synchronously with the roll  10 . 
     As described above, in the embodiment, the unit  30   a  adjusts the rotations of the rolls  10 ,  11  to control the conveying speed of the web  2  in the line  1 . 
     The tension control unit  30   b  adjusts the motor  16   c  of the arm  16   a  connected to the unit  30 , to control the angle of the arm  16   a  to “the predetermined angle θ.” “The predetermined angle θ” means the angle θ between the perpendicular from the point  16   b  and the arm  16   a,  and is set in advance such that the tension of the web  2  in the line  1  becomes the predetermined value in response to the angle of the arm  16   a  (see  FIG. 1 ). 
     In detail, an angle detection device (not shown) is provided near the point  16   b  to detect the angle θ between the perpendicular from the point  16   b  and the arm  16   a,  and the angle detection device is connected to the unit  30  to transmit the detect signal. The unit  30   b  adjusts the motor  16   c  to control the angle θ of the arm  16   a  to the predetermined angle θ on the basis of the received signal. 
     As described above, in the embodiment, the unit  30   b  changes the swinging of the arm  16   a  to control the distance between the fixed rolls  19  and the dancer roll  16 , and the tension of the web  2  is set to the predetermined value (target tension). 
     The speedometer  32  (e.g. Doppler meter) measures the conveying speed of the web  2  adjusted by the unit  30   a  as the real speed. The tension meter  33  (e.g. tension sensor) measures the tension of the web  2  adjusted by the unit  30   b  as the real tension. 
     In detail, the speedometer  32 , for example the laser Doppler meter, is arranged near the guide roll  14 , facing the surface of the roll  14  through the web  2 . The speedometer  32  is connected to the unit  30  and transmits the detected signal to the unit  30 . The conveying speed of the web  2  measured by the speedometer  32  corresponds to the actual conveying speed (real speed) of the web  2  in the line  1 . 
     The tension meter  33 , for example the contact-type tension sensor, is arranged near the guide roll  14 , contacting the web  2  in the line  1 . The tension meter  33  is connected to the unit  30  and transmits the detected signal to the unit  30 . The tension of the web  2  measured by the tension meter  33  corresponds to the actual tension (real tension). 
     The slip amount measuring unit  30   c  measures the “slip amount of the web  2 ,” using the difference between the conveying speed of the web  2  measured by the speedometer  32  and the rotational speed of the guide roll  14  measured by the encoder  34  (see formula 1). When the web  2  doesn&#39;t slip with regard to the roll  14 , the conveying speed of the web  2  should be equal to the rotational speed of the roll  14 . Actually, there exists air or the like between the web  2  and the roll  14 , so that the speeds of them are not equal. So, in the embodiment, the difference between the conveying speed of the web  2  and the rotational speed of the roll  14  is estimated to be the slip amount of the web  2 . 
       SLIP AMOUNT=|CONVEYING SPEED OF WEB−ROTATIONAL SPEED OF GUIDE ROLL|[Formula 1] 
     The encoder  34  is disposed at the drive shaft of the guide roll  14 , detects the rotational speed (number of revolution) of the roll  14  and transmits the detected signal to the unit  30 . The unit  30  measures the slip amount of the web  2  using the formula 1 on the basis of the detected signals from the speedometer  32  and encoder  34 . 
     As shown in  FIG. 3 , the unit  30   c  stores a correlation table  35  regarding the relationship between the slip amount W of the web  2  and the tension T of the web  2  in accordance with each of the conveying speeds V (constant) of the web  2 . The correlation table  35  shows that when the conveying speed V of the web  2  is constant (for instance, see “v 2 ” in  FIG. 3 ), the slip amount W lowers in response to the increase of the tension T of the web  2 , and that when the tension T of the web  2  is constant, the slip amount W lowers in response to the increase of the conveying speed V (v 1 &lt;v 2 &lt;v 3 ). Note that the correlation table  35  is drawn before conveying the web  2  in the line  1  and stored in the memory (not shown) of the unit  30 . 
     In the unit  30   c,  the correlation table  35  has a “target slip amount (see “w 1 ” in FIG.  3 )” as a slip amount, in which there does not occur the slip of the web  2  with respect to the guide roll  14 . Generally, the units  30   a,    30   b  control the conveying speed (target speed) and the tension (target tension) of the web  2  to match the target slip amount set in the unit  30   c.    
     The slip amount calculating unit  30   d  calculates the actual slip amount (real slip amount) of the web  2  with respect to the roll  14  in such a way that the real conveying speed and tension measured by the speedometer  32  and tension meter  33  are substituted for the correlation table  35  stored in the unit  30   c.    
     The deciding unit  30   e  decides whether or not the difference between the real slip amount of the web  2  calculated by the unit  30   d  and the target slip amount set by the unit  30   c  is within the threshold range. The threshold range means the range where there does not occur the slip of the web  2  with respect to the roll  14 . 
     The calculating unit  30   f  calculates the ideal tension of the web  2  in case that the conveying speed of the web  2  is constant when the unit  30   e  decides the difference between the real slip amount and the target slip amount goes beyond the threshold range. Note that the unit  30   e  decides the difference between the real slip amount and the target slip amount is within the threshold range, the ideal tension of the web  2  is not calculated. 
     The guide controller  36  controls the drive of the motor (not shown) of the guide roll  14 , swings the roll around the pivot axis and adjusts the relative angle of the roll to the line  1 . In the embodiment, the slip amount is adjusted by controlling the conveying speed and tension of the web  2  and furthermore the controller  36  changes the relative angle to the conveying line so as to cancel the lateral shift of the web  2 , thereby adjusting the lateral position of the web  2 . 
     Note that the guide controller  36  may be included in the control unit  30  of the control device  3 . 
     According to the above-described structure, in the conveying control device  3 , the target conveying speed and target tension of the web  2  are replaced and given as feedback on the basis of the results from the units  30   e,    30   f.  When the unit  30   e  decides that the difference between the real slip amount and the target slip amount goes beyond the threshold range and the unit  30   f  calculates the ideal tension, the ideal tension is set as the target tension and the unit  30   b  control such that the tension of the web  2  becomes the target tension. On the other hand, when the unit  30   e  decides that the difference between the real slip amount and the target slip amount is within the threshold range and the unit  30   f  does not perform the calculation regarding the ideal tension, the setting of the target tension is kept and the unit  30   b  continues to control the tension of the web  2 . Thus, the unit  30   a  continuously controls the conveying speed of the web  2  to the target speed. 
     Then, the conveying control method for the web  2  is described below. 
     As shown in  FIGS. 3 ,  4 , in the embodiment, the conveying control device  3  is used for controlling the slip of the web  2  with respect to the guide roll  14  in the line  1  and for conveying the web  2  continuously, the method includes the following steps. 
     Before the conveying control of the web  2 , the correlation table  35  is drawn, in advance, representing the relationship between the slip amount W of the web  2  and the tension T of the web  2  in accordance with each of the conveying speeds V (constant) of the web  2 . The correlation table  35  is stored in the memory (not shown) of the control unit  30 . In the following explanation of the embodiment, the target speed is set constant (v 2 ), and when the target tension is (t 1 ), the target slip amount is (w 1 ). 
     When the conveying of the web  2  is actually controlled, the real speed and real tension of the web  2  are measured during conveying (S 100 ). Here, in this explanation, the results of measurement of the speedometer  32  and tension meter  33  are assumed to be the real speed v 3  (v 3 &lt;v 2 ) and the real tension t 2  (t 2 &lt;t 1 ). Then, using the measured value (the real speed v 3  and the real tension t 2 ), the real slip amount w 2  of the web  2  is picked on the basis of the correlation table  35  (S 101 ). 
     In the next step, it is decided whether the difference between the real slip amount w 2  of the web  2  and the target slip amount w 1  is within the threshold range or not (S 102 ). Deciding the difference between the real slip amount w 2  of the web  2  and the target slip amount w 1  goes beyond the threshold range, the ideal tension t 3  of the web  2  with respect to the target slip amount w 1  when setting the real speed of the web  2  to constant (v 3 ) is calculated (S 103 ). 
     The ideal tension (t 3 ) calculated in the above step is set as the target tension of the conveyed web  2  (S 104 ), controlling such that the tension of the conveyed web  2  becomes the ideal tension t 3  (S 106 ). Note that, at the same time, the conveying speed of the web  2  is adjusted to the target speed v 2 , and the web  2  is consequently conveyed at the target speed v 2  and target tension t 1 . 
     On the other hand, decided whether the difference between the real slip amount w 2  of the web  2  and the target slip amount w 1  is within the threshold range or not (S 102 ), and the difference between the real slip amount w 2  of the web  2  and the target slip amount w 1  is decided to be within the threshold range and the and the target tension is set to the target tension t 1  (S 105 ), and controlling such that the tension of the web  2  becomes the target tension t 1  (S 106 ). 
     The guide controller  36  controls the relative angle of the guide roll  14  to the line  1 , adjusting the lateral position of the web  2  (S 107 ). 
     As described above, the conveying control method for the web  2  of the embodiment includes a web measurement step of measuring the conveying speed V and tension T of the web  2  in conveyed, a slip amount calculation step of calculating the slip amount W of the web  2  with respect to the guide roll  14  using the conveying speed V and tension T of the web  2  measured by the web measurement step, a web control step of controlling the tension of the web  2  in conveyed such that the slip amount W of the web  2  calculated in the slip amount calculation step becomes the target slip amount W 1  set in advance, so that the slip of the web  2  is accurately controlled and the lateral shift of the web  2  is lowered. 
     More specifically, the control method of the embodiment is to control the conveying speed and tension of the web  2  on the basis of the slip amount of the web  2  with respect to the guide roll  14 , accordingly, when the “disturbance” occurs and the conveying speed or tension of the web  2  change, the conveying speed and tension of the web  2  are controlled by using the slip amount of the web  2  with respect to the roll  14 , so that the slip of the web  2  is accurately controlled. Furthermore, the slip of the web  2  is controlled by above method; as a result, the shift (lateral shift) of the web  2  with respect to the roll  14  is prevented. The operation of the guide roll  14  makes the control for the lateral position of the web  2  stable, which results in improvement in the accuracy of the lateral position of the web  2 . 
     Especially, in the embodiment, the web control step is the step of deciding whether difference between the slip amount W calculated in the slip amount calculation step and the preset target slip amount W 1  is within the threshold range or not, and when decided the difference goes beyond the threshold range, calculating the ideal tension of the web  2  with regard to the target slip amount W 1  in case that the conveying speed of the web  2  is constant and controlling the tension of the web  2  to meet the calculated ideal tension, therefore, controlling the conveying speed or tension makes it easy to control the web  2  without slipping with respect to the guide roll  14 . 
     Additionally, in the embodiment, as a slip amount measurement step for the web  2 , a step of measuring the rotational speed of the guide roll  14  is included and the slip amount W of the web  2  is measured on the basis of the difference between the conveying speed of the web  2  and the rotational speed of the drive shaft of the guide roll measured by the above-step. Such a measurement method achieves the low relative-error between the conveying speed of the web  2  and the rotational speed of the guide roll  14 , thereby enhancing the accuracy such as the control of the slip of the web  2 . 
     The structures of the conveying control method of the web  2  and the conveying control device  3  are not limited to the above-described embodiment. 
     Note that in the following explanation, the same structures as above-described embodiment are given the same numerals and abridged. 
     The slip amount measuring method of the first embodiment described before is based on the difference between the conveying speed of the web  2  and the rotational speed of the guide roll  14  measured by the suitable method of measuring the rotational speed of the guide roll, and in the second embodiment shown in  FIG. 5 , the slip amount of the web  2  is measured on the basis of the difference between the rotational speed of the start roll  10  measured by the encoder  31  and that of the guide roll  14  measured by the encoder  34  as the measuring method (see formula 2). 
       SLIP AMOUNT=|ROTATIONAL SPEED OF START ROLL−ROTATIONAL SPEED OF GUIDE ROLL|  [Formula 2] 
     In this embodiment, the speedometer  32  may not be disposed for measuring the real speed of the web  2  with respect to the guide roll  14 . In addition, the rolls of measurement objects may be selected as the guide roll  14  and the guide roll  13  disposed near the roll  14 , without limiting the selection of the guide roll  14  and the start roll  10 , and may be measured the difference of the rotational speeds of them. 
     Moreover, as the slip amount measurement method for the web  2 , the third embodiment shown in  FIG. 6  provides a lifting amount detect sensor  132  for detecting the lifting amount of the web  2  from the surface of the guide roll  14  and the method of measuring the slip amount of the web  2  with regard to the guide roll  14  on the basis of the lifting amount of the web  2  (see formula 3). The lifting amount detect sensor  132  is, for example, composed of a non-contact laser sensor, and detects the distance between the surface of the roll and the web  2 . 
       SLIP AMOUNT=|LIFTING AMOUNT OF WEB|  [Formula 3] 
     The distance between the surface of the roll and the web  2  relates to the “slip” of the web  2  on the guide roll  14 , and the distance between the surface of the roll and the web  2  goes beyond the given value, then the same phenomenon may occur as the slip of the web  2  with respect to the guide roll  14 . In the case, the reason of changing the distance between the surface of the guide roll  14  and the web  2  is thought to be an air-entry into the space between the surface of the roll and the web  2  caused by quickening the conveying speed of the web  2 . Furthermore, as to the embodiment, the encoder  34  may not be disposed for measuring the rotational speed of the guide roll  14 . 
     The conveying control device  3  stores the correlation table  35  showing the relationship between the slip amount W of the web  2  and the tension T of the web  2  in accordance with each of the conveying speeds V (constant) of the web  2 , however, the contents or the drawing method of the correlation table  35  is not limited. For example, the correlation table may show the relationship between the between the slip amount W of the web  2  and the conveying speed V of the web  2  in accordance with each of the tensions T (constant) of the web  2 . In this case, the conveying control performs such that the tension of the web  2  becomes constant, the conveying speed is likewise adjusted to the target speed or ideal speed. 
     The structures of the rolls provided in the conveying line  1  may be nip rolls or bridle rolls. Further, the various measuring instruments may be employed for the above-described structure. The web  2  conveyed in the line  1  is not limited to the electrode member (sheet) and may be a long work continuously conveyable. 
     INDUSTRIAL APPLICABILITY 
     The present invention is applicable to the conveying control when continuously conveying the long work (“web”), such as electrode member, using the rolls disposed in the conveying line.