Patent Application
20100108733
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.
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.
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.
First of all, the whole structure of a conveying line 1 for a web 2 will be described below.
As shown in
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 10a, and the motor 10a is connected to a control unit 30. The feed roll 11 is connected to a motor 11a, 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 16a, which is swingably supported on a support point 16b by the other end thereof. The arm 16a is connected to a motor 16c, and the motor 16c 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 16a. 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
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
The conveying speed control unit 30a adjusts the motors 10a, 11a, 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 30a adjusts the motor 10a such that the roll 10 rotates at the target speed on the basis of the received signal. In the embodiment, the unit 30a also adjusts the roll 11 to rotate synchronously with the roll 10.
As described above, in the embodiment, the unit 30a 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 30b adjusts the motor 16c of the arm 16a connected to the unit 30, to control the angle of the arm 16a to “the predetermined angle θ.” “The predetermined angle θ” means the angle θ between the perpendicular from the point 16b and the arm 16a, 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 16a (see
In detail, an angle detection device (not shown) is provided near the point 16b to detect the angle θ between the perpendicular from the point 16b and the arm 16a, and the angle detection device is connected to the unit 30 to transmit the detect signal. The unit 30b adjusts the motor 16c to control the angle θ of the arm 16a to the predetermined angle θ on the basis of the received signal.
As described above, in the embodiment, the unit 30b changes the swinging of the arm 16a 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 30a as the real speed. The tension meter 33 (e.g. tension sensor) measures the tension of the web 2 adjusted by the unit 30b 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 30c 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'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
In the unit 30c, the correlation table 35 has a “target slip amount (see “w1” 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 30a, 30b 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 30c.
The slip amount calculating unit 30d 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 30c.
The deciding unit 30e decides whether or not the difference between the real slip amount of the web 2 calculated by the unit 30d and the target slip amount set by the unit 30c 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 30f calculates the ideal tension of the web 2 in case that the conveying speed of the web 2 is constant when the unit 30e decides the difference between the real slip amount and the target slip amount goes beyond the threshold range. Note that the unit 30e 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 30e, 30f. When the unit 30e decides that the difference between the real slip amount and the target slip amount goes beyond the threshold range and the unit 30f calculates the ideal tension, the ideal tension is set as the target tension and the unit 30b control such that the tension of the web 2 becomes the target tension. On the other hand, when the unit 30e decides that the difference between the real slip amount and the target slip amount is within the threshold range and the unit 30f does not perform the calculation regarding the ideal tension, the setting of the target tension is kept and the unit 30b continues to control the tension of the web 2. Thus, the unit 30a 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
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 (v2), and when the target tension is (t1), the target slip amount is (w1).
When the conveying of the web 2 is actually controlled, the real speed and real tension of the web 2 are measured during conveying (S100). Here, in this explanation, the results of measurement of the speedometer 32 and tension meter 33 are assumed to be the real speed v3 (v3<v2) and the real tension t2 (t2<t1). Then, using the measured value (the real speed v3 and the real tension t2), the real slip amount w2 of the web 2 is picked on the basis of the correlation table 35 (S101).
In the next step, it is decided whether the difference between the real slip amount w2 of the web 2 and the target slip amount w1 is within the threshold range or not (S102). Deciding the difference between the real slip amount w2 of the web 2 and the target slip amount w1 goes beyond the threshold range, the ideal tension t3 of the web 2 with respect to the target slip amount w1 when setting the real speed of the web 2 to constant (v3) is calculated (S103).
The ideal tension (t3) calculated in the above step is set as the target tension of the conveyed web 2 (S104), controlling such that the tension of the conveyed web 2 becomes the ideal tension t3 (S106). Note that, at the same time, the conveying speed of the web 2 is adjusted to the target speed v2, and the web 2 is consequently conveyed at the target speed v2 and target tension t1.
On the other hand, decided whether the difference between the real slip amount w2 of the web 2 and the target slip amount w1 is within the threshold range or not (S102), and the difference between the real slip amount w2 of the web 2 and the target slip amount w1 is decided to be within the threshold range and the and the target tension is set to the target tension t1 (S105), and controlling such that the tension of the web 2 becomes the target tension t1 (S106).
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 (S107).
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 W1 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 W1 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 W1 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
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
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.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-119877 | Apr 2007 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/057225 | 4/7/2008 | WO | 00 | 10/15/2009 |
