JP2012187788A - Method of controlling clip chain running speed of drawing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of controlling clip chain running speed, by which the running speeds of a pair of clip chains can be precisely matched with each other by an inexpensive device.SOLUTION: In the clip device 1 of the drawing device, first and second clip chains 2a, 2b are run by first and second driving sprockets 7a, 7b driven by first and second driving motors 9a, 9b with an encoder 8. First and second count values (Lp, Rp) are obtained by counting the output pulse of the encoder and are reset to zero for every one cycle of the first and second driving sprockets. Thereby, the First and second count values (Lp, Rp) mean the rotation angle of the first and second driving sprockets. The deviation of the First and second count values (Lp, Rp) is obtained to correct the rotation speed of the second driving motor so as to eliminate the deviation.

Description

  The present invention relates to a pair of clip chains provided on the left and right sides with respect to the film flow direction, in a stretching device that grips both ends of the film with the respective clips and centrifuges in the width direction. The present invention relates to a method for controlling traveling speed.

  If a film formed of an oriented resin is stretched in an atmosphere with an intermediate temperature between the softening point and the melting point, a film with a high tensile strength, a film with orientation, etc. can be obtained. This apparatus is conventionally known as a stretching apparatus. As the stretching apparatus, there are known a uniaxial stretching apparatus that stretches the film in only one direction in the length direction and a biaxial stretching apparatus that can stretch the film in two directions of the length direction and the width direction. Thus, a clip device is provided in a stretching device for stretching the film in the width direction. The clip device is well known without mentioning the literature, and is composed of a pair of clip chains provided on the left and right with respect to the film flow direction. The clip chain is composed of a plurality of clips that hold the end of the film, and these clips are connected to each other endlessly. Such a pair of clip chains are guided by a pair of left and right rails arranged on both sides of the film to be fed and run so as to be slightly separated from each other in the film feeding direction. Such a clip device is provided inside a furnace that maintains a predetermined temperature atmosphere. Therefore, when both ends of the film are gripped by the respective clips of the pair of clip chains and the pair of clip chains are run by the left and right drive sprockets, the film is moved in the width direction in a predetermined temperature atmosphere. It will be stretched.

  In the stretching apparatus, it is necessary to match the traveling speeds of the one and the other clip chains so that no orientation difference occurs in the stretched film. For example, a stretching device is well known in which left and right drive sprockets are driven and each motor and a controller that controls these motors in synchronization are provided. In such an apparatus, the rotation speed of the motor itself is synchronized by the controller, and the rotation of the driving sprocket is synchronized, so that the traveling speeds of the pair of clip chains are matched.

JP 2006-224464 A

  Patent Document 1 also describes a method for controlling the traveling speed of a pair of clip chains. According to Patent Document 1, a plurality of continuous clips, for example, six clips are managed as a clip group, and in each clip group, a sensor is pasted on a specific one clip, and this is designated as a specific clip. And The detection body is detected by a sensor provided in the vicinity of the clip chain. According to the control method described in Patent Document 1, a specific clip is detected when the clip chain travels. Then, the traveling speed for each clip group can be obtained. The measured traveling speed of the clip group is compared with the reference speed of the film production line, and if there is a deviation, the traveling speed is adjusted. In both clip chains, when the running speed of the clip group is controlled to match the reference speed, the running speeds of the pair of clip chains are matched.

  Even with a conventional controller having a control function for synchronizing motors, the left and right motors rotate synchronously and the traveling speeds of a pair of clip chains match, so the film is stretched uniformly and the orientation difference is A film having a relatively high quality which is difficult to occur can be obtained. However, there are also problems to be solved. Specifically, such motors and controllers are inferior in versatility and are generally very expensive, so that there is a problem that the entire apparatus cannot be provided at low cost. According to the clip chain running speed control method described in Patent Document 1, the running speed is detected for each clip group and controlled so as to match the reference speed of the film production line. The traveling speeds will agree to some extent. However, in the control method described in Patent Document 1, since the traveling speed is detected in units of clip groups, it cannot be said that the accuracy of speed detection is high. That is, since the traveling speed of each clip is not detected but the average traveling speed of a plurality of clips is detected, it is difficult to obtain an accurate speed. Furthermore, the total number of clips making up the clip chain must be a multiple of the number of clips per clip group, which reduces design freedom. In addition, since the specific clip must be provided with a special detection body, if the number of clips is large, maintenance becomes difficult.

  The present invention aims to provide a method for controlling the running speed of a clip chain that has solved the above-described problems, and specifically, without hindering the freedom of design of the clip chain, It is an object of the present invention to provide a method for controlling the running speed of a clip chain of a stretching apparatus that can accurately match the running speeds of a pair of clip chains with an inexpensive device.

  In order to achieve the above object, the present invention provides a stretching apparatus for gripping one and the other ends of a film by the respective clips of the first and second clip chains and centrifuging in the width direction. The clip chain is configured as a traveling speed control method for traveling in synchronization. The first and second clip chains are independently driven by rotating the first and second sprockets by first and second motors with encoders, respectively. The output pulses of these encoders are counted to obtain the first and second count values of the first and second motors, and correspond to the first and second rotation angles of the first and second sprockets. The first and second count values are reset to 0 every time the sprocket makes one revolution. Then, the first and second count values are compared to obtain a difference between the first and second rotation angles, and the rotational speed of the second motor is corrected so that the difference is eliminated.

Thus, in order to achieve the above-mentioned object, the invention described in claim 1 is a drawing apparatus in which one end of the film is gripped by the respective clips of the first and second clip chains and the film is centrifuged in the width direction. When the first and second sprockets are rotated by the first and second motors with an encoder, respectively, and the first and second clip chains are independently driven, the output pulses of the encoder are counted. The first and second count values of the first and second motors correspond to the first and second rotation angles of the first and second sprockets, respectively, and each of the first and second count values Is reset to 0 each time the first and second sprockets make a round, and the first and second count values are compared, thereby obtaining the difference between the first and second rotation angles. Configured so as to correct the rotational speed of the second motor so it is eliminated.
According to a second aspect of the present invention, in the control method of the first aspect, the first and second count values are configured to be reset to 0 even when the stretching apparatus starts operation.

  As described above, according to the present invention, in the stretching device that grips one and the other end of the film by the respective clips of the first and second clip chains and centrifuges in the width direction, the first and second with an encoder are provided. The first and second sprockets are rotated by the respective motors, respectively, and the first and second clip chains are independently driven. That is, since it is only driven by a general-purpose encoder-equipped motor, the cost of the entire apparatus can be reduced, and a method for controlling the traveling speed of the clip chain at a low cost can be provided. The first and second count values of the first and second motors obtained by counting the output pulses of the encoder are made to correspond to the first and second rotation angles of the first and second sprockets, respectively. Since it is configured, the first and second rotation angles can be easily detected. Further, each of the first and second count values is configured to be reset to 0 every time the first and second sprockets make one round, so that it can be controlled stably. Normally, such a count value is not reset frequently and is accumulated until the maximum count value is reached. However, even if an error occurs in the apparatus, the count value cannot be easily corrected. On the other hand, in the present invention, the sprocket is reset to 0 each time it makes one revolution, that is, it is reset to 0 frequently, so even if an error occurs in the device, it is reset to 0 and the count value is easily set. It is also possible to correct. Furthermore, the process related to resetting the count value is generally a process in which defects in the control program are likely to be mixed. However, in the present invention, the reset is frequently performed. An effect unique to the present invention that the control program is easily discovered and the reliability of the control program is increased can also be obtained. In the present invention, such first and second count values are compared, thereby obtaining a difference between the first and second rotation angles, and correcting the rotational speed of the second motor so that the difference is eliminated. Therefore, the traveling speed is controlled by using the first clip chain as a master, and the second clip chain is operated as a slave by setting the traveling speed to the first clip chain so as to match the traveling speed. It can be corrected. That is, the traveling speeds of the first and second clip chains can be easily matched.

It is a block diagram which illustrates typically the control method which concerns on embodiment of this invention which controls the running speed of the clip chain of an extending | stretching apparatus. It is a flowchart which illustrates typically the process of the control method which concerns on embodiment of this invention which controls the running speed of the clip chain of an extending | stretching apparatus. It is a graph which shows change in the count value of the motor with an encoder which drives a clip chain in the control method concerning an embodiment of the invention which controls the running speed of a clip chain of an extending device.

  Embodiments of the present invention will be described below. A stretching apparatus according to an embodiment of the present invention, like a conventionally known stretching apparatus, maintains an interior at a predetermined temperature atmosphere and a furnace having an inlet and an outlet for a film, and a clip provided in the furnace. It consists of devices. FIG. 1 schematically shows a clip device 1. The clip device 1 is also well known in the art without mentioning the literature, and is composed of a pair of clip chains, that is, first and second clip chains 2a and 2b. The first and second clip chains 2a and 2b are provided symmetrically with respect to the flow direction of the film F. Each clip chain 2a, 2b is composed of a plurality of clips 3, 3,... Connected endlessly, and is guided by a circulating rail 4, guide gears 6, 6 and the like. The first and second clip chains 2a and 2b are driven by the first and second drive sprockets 7a and 7b, respectively. Since the pair of rails 4 and 4 are arranged so as to spread toward the end in the flow direction of the film F, the first and second clip chains 2a and 2b travel in a direction away from each other. It will be stretched in the width direction. Since the clips 3, 3,... Are also well known, description of the specific structure is omitted, but the film F is closed by the clip closer provided in the vicinity of the rails 4, 4 and opened by the clip opener. The film F is released. The clip closer and clip opener are not shown in FIG. Since the clip device 1 is configured as described above, the first and second drive sprockets 7a and 7b are driven to run the first and second clip chains 2a and 2b in a furnace having a predetermined temperature atmosphere. When the film F is sent to the clip device 1, the film F is gripped by the respective clips 3, 3,... Of the clip chains 2, 2, and stretched in the width direction, and the clips 3, 3,. The film F is opened and sent out of the apparatus.

  In the present embodiment, the first and second drive sprockets 7a and 7b are independently driven by first and second drive motors 9a and 9b with encoders 8 and 8, respectively. That is, it is driven by a general-purpose motor. These first and second drive motors 9a and 9b are controlled by the controller 11 according to the present embodiment. The traveling speeds of the first and second clip chains 2a and 2b are determined by the rotational speeds of the first and second drive sprockets 7a and 7b. In the present embodiment, the traveling speed of the second drive sprocket 7b is determined. The rotational speed of the second drive motor 9b is corrected so that the rotational speed matches the rotational speed of the first drive sprocket 7a. As a result, the traveling speeds of the first and second clip chains 2a and 2b are matched. Hereinafter, the controller 11 will be described.

  A block diagram schematically showing the processing of the controller 11 is shown in FIG. 1, but the controller 11 is provided with a speed setting device 12, and the rotation speed that is the reference of the drive sprocket, that is, the reference rotation speed is this speed. It is set in the setting device 12. When the reference rotation speed is set, it is input to the inverter 15 that drives the first drive motor 9a. The reference rotational speed is also input to the adder 19, and the corrected rotational speed described below is added to the inverter 15, which drives the second drive motor 9b.

  The controller 11 is provided with first and second high-speed counters 13a and 13b, and pulses output from the encoders 8 and 8 of the first and second drive motors 9a and 9b are input via the isolators 14 and 14, respectively. Has been. The first and second high-speed counters 13a and 13b count pulses to obtain first and second count values, respectively. These first and second count values are associated with the rotation angles of the drive sprockets 7a and 7b, respectively, and are reset to 0 each time the drive sprockets 7a and 7b make one revolution, as will be described later. Yes. The first and second count values are input to the comparator 17, and the difference between the first and second count values, that is, the deviation is calculated as described later. The deviation is multiplied by minus and input to the PI controller 18, and the corrected rotation speed corresponding to the deviation is calculated and input to the adder 19 described above. The adder 19 is also supplied with the rotational speed for calibration set in the correction speed setter 20, and the rotational speed for calibration is the first and second drive motors 9a, 9b or these. Is used to correct this when there is a difference in the characteristics of the respective inverters 15 and 15 that drive, and normally 0 is set. In the adder 19, the correction rotation speed and the calibration rotation speed are added to the reference rotation speed output from the speed setting device 12, and the correction rotation speed and the calibration rotation speed are input to the inverter 15 that drives the second drive motor 9b. ing.

  The operation of the clip device 1 including the controller 1 according to the present embodiment will be described. The controller 11 is started. As shown in FIG. 2, the controller 11 resets the first and second count values Lp and Rp to 0 in step S1. As a result, the rotation angles of the first and second drive sprockets 7a and 7b are initialized. When the controller 11 is started, a predetermined reference rotational speed set in the speed setter 12 is input to the inverters 15 and 15 of the first and second drive motors 9a and 9b, and the first and second drive motors 9a and 9b are input. 9b rotates so that it may become a reference | standard rotational speed each independently. When the furnace of the stretching apparatus is set to a predetermined temperature and the film F is sent to the clip apparatus 1, the film F is stretched as conventionally known. The first and second high-speed counters 13a and 13b of the controller 11 count pulses output from the encoders 8 and 8, and calculate first and second count values Lp and Rp. At this time, in steps S2 and S3, it is determined whether or not the count value has reached the maximum count value P corresponding to one turn of the drive sprockets 7a and 7b. Reset to. The rotation angles of the first and second drive sprockets 7a and 7b can be found from the first and second count values Lp and Rp calculated in this way.

The comparator 17 calculates a deviation B between the first and second count values Lp and Rp. As described above, since the first and second count values Lp and Rp are reset every time the maximum count value P is exceeded, the difference cannot be simply calculated. The deviation B is calculated as follows. First, in step 6, it is checked whether or not the absolute value of the difference between the first and second count values Lp and Rp is greater than ½ of the maximum count value P. If it is smaller than 1/2 of the maximum count value P, the first and second count values Lp and Rp are compared in step S7. When the first count value Lp is larger, the deviation B is calculated as follows in step S8.
B = | Lp−Rp |
When the second count value Rp is larger, the deviation B is calculated as follows in step S9.
B =-| Lp-Rp |
When the absolute value of the difference between the first and second count values Lp and Rp is larger than ½ of the maximum count value P, the magnitudes of the first and second count values Lp and Rp are compared in step S10. When the first count value Lp is larger, the deviation B is calculated as follows in step S11.
B = | Lp−Rp | −P
When the second count value Rp is larger, the deviation B is calculated as follows in step S12.
B = P- | Lp-Rp |

  FIG. 3A shows a graph of changes in the count values Lp and Rp when the clip device 1 is operated. The first count value Lp is a solid line, The count value Rp is indicated by a dotted line. The upper graph shows a state where the first count value Lp is ahead of the second count value Rp, that is, a state where the first drive sprocket 7a is ahead of the first drive sprocket 7b. Yes. The deviation B is calculated in steps S9 and S11 and becomes like the lower graph. Further, in the upper graph of FIG. 3B, the first count value Lp is delayed from the second count value Rp, that is, the first drive sprocket 7a is the first drive sprocket 7b. A more delayed state is shown. The deviation B is calculated in steps S8 and S12 and becomes like the lower graph.

  When the deviation B is calculated in this way, the process returns to Step S2 and Step S3 and is repeated. The calculated deviation B is multiplied by minus and sent to the PI controller 18. That is, in the PI controller 18, since it is necessary to calculate the corrected rotation speed so as to eliminate the deviation B, the input of the PI controller 18 is multiplied by minus. The PI controller 18 calculates the corrected rotation speed and sends it to the adder 19. When the correction rotational speed and the calibration rotational speed of the reference rotational speed are set in the adder 19, the calibration rotational speed is also added and sent to the inverter 15 of the second drive motor 9b. As a result, the rotational speed of the second drive motor 9b is corrected to coincide with the rotational speed of the first drive motor 9a, and the first and second drive sprockets 7a and 7b are synchronized. That is, the first and second clip chains 2a and 2b are synchronized.

1 Clip device
2a First clip chain 2b Second clip chain 3 Clip 4 Rail 7a First drive sprocket 7b Second drive sprocket 8 Encoder 9a First drive motor 9b First drive motor 11 Controller 12 Speed setter 13a First 1 high-speed counter 13b second high-speed counter 17 comparator 19 adder

Claims (2)

In a stretching device that grips one and the other end of the film with the respective clips of the first and second clip chains, and centrifuges in the width direction, the first and second sprockets are respectively driven by the first and second motors with an encoder. To rotate the first and second clip chains independently,
The first and second count values of the first and second motors obtained by counting the output pulses of the encoder correspond to the first and second rotation angles of the first and second sprockets, Each of the first and second count values is reset to 0 every time the first and second sprockets make one revolution,
The first and second count values are compared to thereby obtain a difference between the first and second rotation angles, and the rotational speed of the second motor is corrected so that the difference is eliminated. A method for controlling the running speed of a clip chain of a film stretching apparatus. 2. The control method according to claim 1, wherein the first and second count values are reset to 0 even when operation of the stretching apparatus is started.

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