JP5922007B2 - Method for controlling clip chain traveling speed of stretching device - Google Patents

Description

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

  When a film formed of an oriented resin is stretched in an atmosphere at a temperature between the softening point and the melting point, a film having a high tensile strength, a film with orientation, and the like can be obtained. The device for this is conventionally known as a stretching device. 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. As described above, the stretching device for stretching the film in the width direction is provided with a clip device. 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 traveling direction of the film. 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 while being slightly separated from each other in the film feeding direction. Such a clip device is provided in a furnace maintained in 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 stretched in the width direction in a predetermined temperature atmosphere. Will be.

  In the stretching apparatus, it is necessary to match the traveling speeds of the pair of clip chains so that no orientation difference occurs in the stretched film. Thus, the extending | stretching apparatus which matches the traveling speed of a clip chain is known, for example, is provided with a pair of electric motor which drives a pair of sprockets for clip chain drive, and a controller which controls these synchronously. In such a device, 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 this method, a plurality of continuous clips, for example, six clips, are managed as a clip group, and in each clip group, a sensor is attached to one specific clip, and this is used as a specific clip. The detecting body is detected by a sensor provided in the vicinity of the clip chain. Therefore, when the clip chain travels, if a specific clip is detected, the travel 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. That is, if the left and right clip chains are controlled so that the running speed of the clip group matches the reference speed, the running speeds of the pair of clip chains will match.

  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 a difference in orientation occurs. Difficult and relatively good quality films can be obtained. However, there are also problems to be solved. Such a motor is equipped with an encoder that counts output pulses to detect the rotational position, but when the machine is stopped and the supply of power is stopped, the controller that stores the count number also has When the operation stops and the operation is resumed, there may be a deviation between the rotational position and the count. If the amount of deviation differs between the left and right motors, the left and right motors cannot be substantially rotated in synchronization. In order to prevent such a deviation between the rotational position and the count number, for example, it is necessary to protect the count number when the controller is stopped or to back up the power supply of the controller. In this case, not only the entire apparatus becomes complicated, but also there is a problem that an expensive controller consisting of a dedicated machine must be provided and the entire apparatus cannot be provided at low cost. There is also a problem with the method for controlling the running speed of the clip chain described in Patent Document 1. According to this control method, since the traveling speed is detected for each clip group and controlled to match the reference speed of the film production line, the traveling speeds of the left and right clip chains are matched to some extent, but the traveling speed is Therefore, the accuracy of speed detection cannot be said to be 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, resulting in a low degree of design freedom. In addition, since the specific clip must be provided with a special detection body, the cost is high when the number of clips is large.

  Moreover, a common problem is seen in the conventional method and the control method described in Patent Document 1. That is, in these methods, when a relative deviation occurs between the left and right clip chains that travel, control is performed so as to always eliminate this deviation. Originally, if this deviation is an integral multiple of the clip length, the clips in the left clip chain should be aligned with the clips in the right clip chain. It is useless to control to eliminate misalignment.

  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 traveling speed of a clip chain of a stretching device that can accurately and efficiently synchronize a pair of clip chains with an inexpensive device.

  In order to achieve the above object, the present invention provides a first clip chain in a stretching apparatus that grips one end of the film by the respective clips of the first and second clip chains and stretches in the width direction. The traveling speed of the second clip chain is adjusted with respect to the traveling speed, and the control method is configured to synchronize the first and second clip chains. In the stretching apparatus that implements this control method, the first and second sprockets on which the first and second clip chains are respectively wound have an even number of teeth, and one clip is formed by two teeth. It comes to mesh. Each of these sprockets is managed by the rotational position from the reference rotational position. The rotational speed of the second sprocket is controlled so that the relative difference between the rotational positions of the first and second sprockets is an even number of sprocket teeth. That is, the traveling speed of the second clip chain is adjusted.

Thus, in order to achieve the above object, according to the first aspect of the present invention, the first and second clip chains in which a plurality of clips are connected to each other, and the number of teeth is an even number and two for one clip. A first and a second sprocket adapted to feed out the first and second clip chains with meshed teeth, and a first and a second motor for driving the first and second sprockets, respectively. In the stretching apparatus that grips one end of the film and the other end of the film with the respective clips of the first and second clip chains and stretches in the width direction, the traveling speed of the second clip chain is adjusted to adjust the travel speed of the second clip chain. A method for controlling the travel speed of a clip chain synchronized with the travel speed of one clip chain, the control method comprising: detecting rotation positions of the first and second sprockets; A position detection process, a deviation inspection process for inspecting the deviation of the first and second clip chains, and a rotational speed adjustment process for adjusting the rotational speed of the second sprocket. First and second count values corresponding to the rotational positions of the first and second sprockets are provided, and the first and second count values are counted as output pulses from encoders provided in the first and second motors. And each time the first and second sprockets reach a reference rotational position, they are reset to 0, and the deviation inspection process is an evaluation value for evaluating the deviation of the first and second clip chains. b, the maximum count value of output pulses corresponding to one round of the first and second sprockets is P, the number of teeth of the first and second sprockets is G, and the evaluation value b is The absolute value of the difference between the count values of 2 is divided by 2 × P / G, and the rotational speed adjustment processing is performed by calculating a correction amount B for increasing or decreasing the traveling speed of the second clip chain. The correction amount B is given as an evaluation value b-2P / G when [evaluation value b ≧ P / G] and [first count value ≧ second count value], and [evaluation value b ≧ P / G]. G] and [first count value <second count value] are given by evaluation value 2P / G−b, and [evaluation value b <P / G] and [first count value ≧ second count value] ] given by the evaluation value b when, given by [evaluation value b <P / G] and [the first count value <the second count value] evaluation value b × time (-1), the correction amount B An input is calculated by the PI controller to obtain a corrected rotational speed as an output value, and the corrected rotational speed is calculated as the running speed of the second clip chain. Configured as a control method of the traveling speed of the clip chains film stretching apparatus characterized by adding to the speed.

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.
According to a third aspect of the present invention, in the control method according to the first or second aspect, in the rotational position detection process and the rotational speed adjustment process, both the first and second sprockets perform the reference rotation at least once. It is configured to start after detecting that the position has been reached.
According to a fourth aspect of the present invention, in the control method according to any one of the first to third aspects, the first and second sprockets are each provided with a marker, and the reference rotational position is a predetermined sensor. Is configured to be a position where the marker is detected.

  As described above, according to the present invention, it is configured as a method for controlling the traveling speed of the first and second clip chains in the stretching apparatus that grips one end of the film with the clip and stretches in the width direction. The requirement of the device is that the first and second sprockets, which are designed to feed out the first and second clip chains, have an even number of teeth and two teeth mesh with each other. It is only a point. Then, this control method can be implemented in most conventional stretching apparatuses. According to the present invention, the control method includes rotational position detection processing for detecting the rotational positions of the first and second sprockets, deviation inspection processing for inspecting the displacement of the first and second clip chains, and rotation of the second sprocket. And a rotational speed adjustment process for adjusting the speed. As will be described in detail later, the rotational positions of the first and second sprockets are accurately grasped by the rotational position detection process, and the deviation of the first and second clip chains is detected by the deviation inspection process. . In the present invention, evaluation is performed based on whether or not the deviation of the rotational positions of the first and second sprockets corresponds to an even multiple of the number of sprocket teeth by the deviation inspection process. If the deviation of the rotational position of the first and second sprockets is not an even multiple of the number of teeth of the sprocket, it is determined that the first and second clip chains are displaced, The traveling speed of the second clip chain is controlled by the rotational speed adjustment process so that the deviation becomes an even multiple. Therefore, according to the present invention, the first and second clip chains are synchronized accurately and efficiently. In the rotational position detection process of the present invention, the following process is specifically performed. In other words, the first and second motors that drive the first and second sprockets are provided with encoders, but the output pulses from these encoders are counted to obtain the first and second count values. It corresponds to the rotational position of the sprockets 1 and 2. Since the first and second count values are reset to 0 each time the first and second sprockets reach the reference rotational position, there is no possibility of errors. 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, every time the sprocket reaches the reference rotational position, that is, every time it makes one revolution, it is reset to 0. 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 is also obtained.

It is a figure which illustrates the control method concerning an embodiment of the invention typically, and is a control block diagram of a controller which controls a drawing device. It is a top view which shows typically the left and right sprocket which runs the right and left clip chain of the extending | stretching apparatus which concerns on this Embodiment. It is a figure which shows typically the right and left sprocket which runs the right and left clip chain of the extending | stretching apparatus which concerns on this Embodiment, The (a) (b) is an upper surface when it exists in a respectively different rotation position about the left and right sprocket. FIG. 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.

  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 circulating rails 4, 4, guide gears 6, 6 and the like. The first and second clip chains 2a and 2b are driven and driven by the first and second 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. Will be stretched. 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 in this way, the first and second sprockets 7a and 7b are driven to run the first and second clip chains 2a and 2b by setting the inside of the furnace to 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,. Thus, the film F is sent out of the apparatus. In the present specification, the first clip chain 2a and the first sprocket 7a are located on the left side when viewed in the flow direction of the film F, so they are called the left clip chain 2a and the left sprocket 7a, respectively. Since 2b and the second sprocket 7b are located on the right, they are called a right clip chain 2b and a right sprocket 7b, respectively.

  In the present embodiment, the first and second sprockets 7a and 7b are independently driven by first and second motors 9a and 9b with encoders 8a and 8b, respectively. That is, it is driven by a general-purpose motor. The first and second motors 9a and 9b are controlled by the controller 11 according to the present embodiment. In the present embodiment, sensors 10 a and 10 b are provided in the vicinity of the first and second sprockets 7 a and 7 b, and signals from the sensors 10 a and 10 b are also input to the controller 11. These sensors 10a and 10b are for detecting markers provided in the first and second sprockets 7a and 7b, respectively. The rotational position of the sprockets 7a and 7b when the marker is detected is referred to as a reference rotational position in this specification. The markers provided on the sprockets 7a and 7b are not shown in FIG.

  In the present embodiment, the left and right sprockets 7a, 7b have an even number of teeth, and two teeth mesh with one clip. Although the number of teeth is actually larger, FIG. 2 shows sprockets 7a and 7b simply having eight teeth. As shown in FIG. 2, the clips 3, 3,... Are composed of clip bodies 3 H, 3 H,... And links 3 L, 3 L,. That is, one clip 3 includes one clip body 3H and one link 3L. Since one tooth meshes with each of the clip main body 3H and the link 3L, two teeth mesh with one clip 3. When the left and right sprockets 7a and 7b rotate in opposite directions, the left and right clip chains 2a and 2b travel in the same direction. In FIG. 2, markers M and M are shown on the left and right sprockets 7a and 7b, and both sprockets 7a and 7b are located at the reference rotation position.

  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 reference rotation speed, that is, the reference rotation speed, of the sprockets 7a and 7b is set. The speed setting unit 12 is set. When the reference rotation speed is set, it is input to the inverter 15a that drives the first motor 9a. The reference rotation speed is also input to the adder 19 and is input to the inverter 15b that drives the second motor 9b.

  The controller 11 is provided with first and second high-speed counters 13a and 13b, and pulses output from the encoders 8a and 8b of the first and second motors 9a and 9b are input via the isolators 14a and 14b, respectively. ing. The first and second high-speed counters 13a and 13b count pulses and calculate first and second count values Lp and Rp, respectively. These first and second count values Lp and Rp are associated with the rotational positions of the sprockets 7a and 7b, respectively, and are reset to 0 each time the sprockets 7a and 7b make one round, as will be described later. ing. The first and second count values Lp and Rp are input to the processing block 17 that performs processing peculiar to the present invention, and a correction amount B required to correct the traveling speed of the second clip chain 2b. Is output. The correction amount B is input to the PI controller 18 to calculate the correction rotation speed, and is 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 motors 9 a and 9 b or these. When there is a difference in the characteristics of the inverters 15 and 15 to be driven, this is used to correct this, 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 motor 9b. . In the present embodiment, the first clip chain 2a is used as a master to run at a predetermined running speed, and the second clip chain 2b is used as a slave to adjust the running speed so as to synchronize with the first clip chain 2a. It has become.

  Hereinafter, the operation of the clip device 1 according to the present embodiment will be described. Before describing specific processing in the controller 11, an outline of control performed by the controller 11 will be described with reference to FIG. When the operation of the clip device 1 is started or during operation, the left and right clip chains 2a, 2b are not necessarily synchronized. For example, FIG. 3A shows a state where the rotational position of the right sprocket 7b is advanced by three teeth with respect to the left sprocket 7a. It can be seen that the clip 3 on the right side and the clip 3 on the right clip chain 2b are displaced by half the length of the clip. In such a state, it is necessary to eliminate the deviation of the clip chains 2a and 2b. FIG. 3A shows a state where the rotational position of the right sprocket 7b is advanced by four teeth with respect to the left sprocket 7a. In this state, the left and right sprockets 7a and 7b are displaced in rotational positions, but the predetermined clip 3 of the left clip chain 2a and the predetermined clip 3 of the right clip chain 2b are aligned. That is, it can be said that the left and right clip chains 2a and 2b are substantially free from displacement. In this case, it is not necessary to eliminate the deviation. Generally, when the shift of the rotational positions of the left and right sprockets 7a and 7b corresponds to an even number of teeth, the left and right clip chains 2a and 2b are synchronized. The controller 11 according to the present embodiment detects a deviation between the left and right sprockets 7a and 7b, and controls the deviation to be an even number of sprocket teeth. This is because the shift between the left and right clip chains 2a and 2b is substantially eliminated.

  Processing of the controller 11 according to the present embodiment will be described. The controller 11 is started. As shown in FIG. 4, the controller 11 resets the first and second count values Lp and Rp to 0 in step S <b> 1. Thereby, the rotation angles of the first and second sprockets 7a and 7b are initialized. When the controller 11 starts, a predetermined reference rotational speed set in the speed setting device 12 is input to the inverters 15 and 15 of the first and second motors 9a and 9b, and the first and second motors 9a and 9b , And rotate independently to the reference rotation speed. 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. In the stage immediately after the start of the operation, the rotation speed adjustment process described later is not performed, and the first and second motors 9a and 9b are operated at the reference rotation speed.

  The controller 11 performs a rotational position detection process for detecting the rotational positions of the first and second sprockets. That is, the first and second high-speed counters 13a and 13b of the controller 11 count the pulses output from the encoders 8a and 8b, and calculate the first and second count values Lp and Rp. When the operation is started, the sprockets 7a and 7b reach the reference rotation position. For the sprockets 7a and 7b that have reached the reference rotational position, the first and second count values Lp and Rp are reset to 0 and the counting is restarted. When it is confirmed that both the first and second sprockets 7a and 7b have reached the reference rotational position even once, control peculiar to the present invention, that is, rotational speed adjustment processing is started. The process of confirming that both sprockets 7a and 7b reach the reference rotational position is shown in step S2 in FIG. The first and second sprockets 7a and 7b do not necessarily have to reach the reference rotation position at the same time, and may reach the reference rotation position at different timings. After reaching, the rotation speed adjustment process is started.

  Thereafter, control peculiar to the present invention is carried out. When the first and second count values Lp and Rp are calculated, when the sprockets 7a and 7b reach the reference rotation position in steps S3 and S4, the steps S5 and S6 are performed. Reset to zero. That is, the sprockets 7a and 7b are reset from the maximum count value P to 0 every time they make one rotation. The first and second count values Lp and Rp calculated in this way correspond to the rotational positions of the first and second sprockets 7a and 7b. That is, obtaining the first and second count values Lp, Rp is nothing but detecting the rotational positions of the sprockets 7a, 7b.

Next, the controller 11 performs a deviation inspection process for inspecting the deviation of the rotational positions of the first and second sprockets. In the deviation inspection process, as shown in step S7, the absolute value of the deviation between the first and second count values Lp and Rp is divided by the output pulse count corresponding to two sprocket teeth. To obtain a quotient a and a remainder b. Specifically, the following equation is calculated.
| Lp−Rp | / (2P / G) = a × n + b
However, if P = maximum count value, G = number of sprocket teeth and the remainder b is 0, the deviation between the left and right sprockets 7a, 7b corresponds to an even number of sprocket teeth. As explained, there is no deviation between the first and second clip chains 2a, 2b. On the other hand, if the remainder b is not 0, the first and second clip chains 2a and 2b are displaced. That is, the remainder b can be said to be an evaluation value b for evaluating the deviation between the left and right clip chains 2a, 2b.

After the deviation inspection process, the controller 11 adjusts the rotation speed of the second sprocket so that the evaluation value b becomes zero. That is, the rotation speed adjustment process is performed. In this process, first, a correction amount B for increasing / decreasing the traveling speed of the second clip chain is calculated, and then, based on the correction amount B, a correction rotational speed that is an increase / decrease amount of the rotational speed of the second sprocket 7b is calculated. Calculate and control the rotational speed of the second sprocket 7b. The correction amount B is calculated as follows.
When b ≧ P / G and Lp ≧ Rp, B = b−2P / G
When b ≧ P / G and Lp <Rp, B = 2P / G−b
When b <P / G and Lp ≧ Rp, B = b
When b <P / G and Lp <Rp, B = −b
These processes are shown in steps S8 to S15. Note that the processing block 17 in FIG. 1 is a block in which deviation inspection processing and processing for calculating the correction amount B in the rotation speed adjustment processing are combined.

  Subsequently, the rotation speed adjustment process is performed. That is, based on the obtained correction amount B, a corrected rotational speed that is an increase / decrease in the rotational speed of the second sprocket 7b is calculated. Specifically, the PI controller 18 calculates the correction rotation speed with the correction amount B as an input. The correction rotation speed is determined so that the positive and negative signs coincide with the sign of the correction amount B, and the magnitude thereof increases in accordance with the magnitude of the correction amount B. For example, the correction rotation speed can be obtained by multiplying the correction amount B by a predetermined constant. The obtained corrected rotation speed is sent to the adder 19. When the reference rotation speed, the correction rotation speed, and the rotation speed for calibration are set in the adder 19, the rotation speed for calibration is also added and sent to the inverter 15 of the second motor 9b. Thereby, the rotational speed of the second motor 9b is controlled. Thus, the second sprocket 7b is controlled such that the rotational position shift of the first and second sprockets 7a and 7b is equal to an even number of sprocket teeth. That is, the first and second clip chains 2a and 2b are synchronized.

DESCRIPTION OF SYMBOLS 1 Clip apparatus 2a, 2b 1st, 2nd clip chain 3 Clip 4 Rail 7a, 7b 1st, 2nd sprocket 8a, 8b Encoder 9a, 9b 1st, 2nd motor 10a, 10b Sensor 11 Controller

Claims (4)

The first and second clip chains in which a plurality of clips are connected to each other, and the number of teeth is an even number and two teeth mesh with each other so that the first and second clip chains are fed out. First and second sprockets, and first and second motors for driving the first and second sprockets, respectively, and one of the films by each clip of the first and second clip chains. In a stretching apparatus that grips the other end and extends in the width direction, the clip chain traveling speed control method that adjusts the traveling speed of the second clip chain and synchronizes with the traveling speed of the first clip chain. Because
The control method includes rotational position detection processing for detecting rotational positions of the first and second sprockets, deviation inspection processing for inspecting displacement of the first and second clip chains, and rotational speed of the second sprocket. The rotation speed adjustment process to adjust
In the rotational position detection processing, first and second count values corresponding to rotational positions of the first and second sprockets are provided, and the first and second count values are provided in the first and second motors. The output pulse from the encoder is counted, and reset to 0 each time the first and second sprockets reach the reference rotational position;
In the deviation inspection process, an evaluation value b for evaluating the deviation of the first and second clip chains is provided, and a maximum count value of output pulses corresponding to one round of the first and second sprockets is set as P. The evaluation value b is obtained as a remainder obtained by dividing the absolute value of the difference between the first and second count values by 2 × P / G, where G is the number of teeth of the first and second sprockets,
The rotational speed adjustment process provides a correction amount B for increasing or decreasing the traveling speed of the second clip chain, and the correction amount B is:
When [evaluation value b ≧ P / G] and [first count value ≧ second count value], the evaluation value b−2P / G is given.
When [evaluation value b ≧ P / G] and [first count value <second count value], the evaluation value 2P / G−b is given.
When [evaluation value b <P / G] and [first count value ≧ second count value], the evaluation value b is given.
When [evaluation value b <P / G] and [first count value <second count value], it is given by evaluation value b × (−1),
The clip chain of the film stretching apparatus, wherein the correction amount B is input by the PI controller to obtain a corrected rotational speed as an output value, and the corrected rotational speed is added to the traveling speed of the second clip chain. How to control the running speed of the car.   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.   3. The control method according to claim 1, wherein the rotation position detection process and the rotation speed adjustment process are performed after detecting that both of the first and second sprockets have reached the reference rotation position at least once. A method for controlling a running speed of a clip chain of a film stretching apparatus, characterized by starting.   4. The control method according to claim 1, wherein each of the first and second sprockets is provided with a marker, and the reference rotational position is a position where the marker is detected by a predetermined sensor. A method for controlling the running speed of a clip chain of a film stretching apparatus.

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