JP2005162227A - Capping method and capping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capping method and a capping device capable of detecting the rotational angle of a cap with high precision even when the detected torque is dispersed. <P>SOLUTION: When capping a so-called ratchet type cap 5, a control means 8 detects the torque generated when a claw part 20 formed on a ring member 19 of the cap 5 rides over a reverse turn preventive claw 15 of a mouth part 11 and the rotational position of a capping head 6. When the newly detected torque from the maximum torque detected at the maximum torque exceeding the maximum torque detection start torque (a) is smaller than a predetermined determination value (b), the rotational position corresponding to the maximum torque is set to be the reference seaming position (c), and the capping is performed by turning the cap 5 before the predetermined seaming completion torque is detected. Acceptance/rejection of the capping is determined by comparing the rotational angle of the capping head from the reference seaming position (c) to the seaming completion with the seaming completion angle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a capping method and a capping device, and more particularly to a capping method and a capping device for tightening a cap while detecting torque acting on a capping head.

Conventionally, a capping method is known in which a cap is tightened while detecting torque acting on the capping head. Among these caps, a so-called ratchet type is known. Capping is performed. (Patent Document 1)
In the case of such a ratchet type cap, a maximum torque is applied to the capping head a plurality of times. In this Patent Document 1, the maximum torque at the maximum of the first applied torque is detected, and a predetermined torque is detected from the maximum torque. The torque indicating the rate of decrease was detected and used as a reference point.
Then, the rotational position of the capping head when this reference point is detected is obtained, and the cap is further tightened by rotating the capping head by a predetermined rotational angle from the rotational position.
JP 11-29191 A

However, in the case of the above-mentioned patent document 1, since the cap is rotated by a predetermined angle from the reference point corresponding to the torque detected at a specific reduction rate from the maximum torque at the torque maximum, for example, the cap is tightened. If the torque acting on the capping head varies due to poor machining accuracy, the position of the detected reference point also varies depending on the magnitude of the detected maximum torque.
For this reason, even if a predetermined rotation angle cap is rotated using this reference point, the tightening state of the cap is not constant, and the cap is insufficiently tightened, or conversely, the cap is excessively tightened. There was a problem.
In addition, as a result of experiments on the tightening of caps where the maximum torque appears when tightening, such as a ratchet cap, the present applicant has found variations in the maximum torque value at which the torque is maximized. However, it has been found that the rotational position of the capping head at which the torque is maximized is consistent.
In view of the above problems, the present invention provides a capping method and a capping device that can detect the rotation angle of the cap with high accuracy when performing capping while detecting the rotation angle.

That is, the capping method according to claim 1 is a capping method in which the cap is tightened while detecting the torque acting on the capping head.
The detected maximum torque and the rotational position of the capping head at that time are stored, and when the difference between the stored maximum torque and the newly detected torque is equal to or greater than a predetermined determination value, the maximum torque is The rotation position of the capping head at the time of detection is used as a winding reference position, and the rotation angle from the winding reference position to the end of winding is detected.

According to a sixth aspect of the present invention, a capping device includes a capping head that holds a cap, a servo motor that rotationally drives the capping head, and a control unit that controls the servo motor, while detecting torque acting on the capping head. In a capping device that winds a cap around a container,
Torque storage means for storing detected torque, comparison means for comparing the difference between the stored torque and the newly detected torque, rotational position detection means for detecting the rotational position of the capping head, and torque Rotational position storage means for storing the rotational position signal when detected, and a set value storage unit for storing a required set value,
When the newly detected torque is greater than the torque stored in the torque storage means, the comparison means stores the newly detected torque as the maximum torque in the torque storage means, and sets the maximum torque to the maximum torque. Store the corresponding position signal in the rotational position storage means,
When the newly detected torque is smaller than the determination value stored in the set value storage unit than the maximum torque stored in the torque storage means, the rotational position of the capping head stored in the rotational position storage means is determined. It is determined that it is a winding tightening reference position, and a rotation angle from the winding tightening reference position to the end of winding tightening is detected.

According to the first and sixth aspects of the invention, the maximum torque can be detected even if the torque acting on the capping head varies even if the shape of the cap is the same regardless of the processing accuracy of the cap. When this is done, the rotational position of the capping head is detected constant.
Accordingly, in the present invention, the rotation position of the cap is detected by using the rotation position of the capping head when the maximum torque is detected as a winding reference position and detecting the rotation angle from the winding reference position to the end of winding. Can be performed with high accuracy.

FIG. 1 shows a capping device 1 according to the present invention, and FIG. 1 shows a mounting table 3 for mounting a container 2 on the upper surface thereof, and a gripper for gripping the container 2 mounted on the mounting table 3. 4, a capping head 6 that holds the cap 5 above the mounting table 3, and a servo motor 7 that moves up and down by a lifting means (not shown) and rotates the capping head 6 that holds the cap 5 in the horizontal direction. Yes.
In such a capping device 1, after gripping the container 2 on the mounting table 3 with the gripper 4, the servo motor 7 is lowered to engage the cap 5 held by the capping head 6 with the mouth of the container 2, Thereafter, the capping is performed by rotating the servo motor 7. In addition, since the capping apparatus 1 itself having such a configuration is conventionally known, detailed description of each part is omitted.
The capping device 1 is provided with a control means 8 for controlling the rotation angle and torque of the servo motor 7 and for controlling the servo motor 7 and detecting the torque acting on the servo motor 7.

Next, the container 2 and the cap 5 will be described. FIG. 2 is an enlarged view of the mouth part 11 of the container 2 and the cap 5 wound around the mouth part 11, and in this embodiment, a so-called ratchet type cap 5 is shown. Has come to handle. Such a cap 5 is disclosed in Japanese Patent Laid-Open No. 10-72096 and has been publicly known.
First, the mouth portion 11 of the container 2 is provided above the main body portion 12, and a flange portion 13 for supporting the gripper 4 from below is formed between the mouth portion 11 and the main body portion 12. Has been.
The mouth portion 11 is formed with a screw portion 14 that is screwed with the cap 5, and a reverse rotation preventing claw 15 that engages with a claw portion 20 of a ring member 18 that will be described later is equidistant along the outer peripheral surface. Is formed.

Next, the cap 5 is made of resin and has a bottomed cylindrical shape, and a screw portion 16 that is screwed with the screw portion 14 of the mouth portion 11 is formed on the inner peripheral surface thereof. Furthermore, an inner ring 17 is provided on the upper surface of the cap 5 to fit the opening of the mouth portion 11 and seal the container 2.
A ring member 18 is connected to the lower side of the cap 5 by a breakable connecting member 19, and a claw portion 20 that engages with the reverse rotation preventing claw 15 of the mouth portion 11 is formed on the inner peripheral surface of the ring member 18. It is provided at equal intervals.
The claw portion 20 will be described. FIG. 3 is a perspective view of the cap 5 as viewed from below. As shown in FIG. 3, the claw portion 20 is formed on the inner peripheral surface of the ring member 18 at equal intervals. .
When the cap 5 is rotated clockwise, the ring member 18 is lowered together with the cap 5, and the claw portion 20 comes into contact with the reverse rotation preventing claw 15.
When the cap 5 is further rotated from here, the claw portion 20 is elastically deformed while climbing over the reverse rotation prevention claw 15 and is restored after being overtaken to engage with the reverse rotation prevention claw 15.
Therefore, according to the claw portion 20 and the reverse rotation prevention claw 15, if the cap 5 is rotated clockwise, the claw portion 20 gets over the reverse rotation prevention claw 15, and thus the rotation is allowed. Even if the claw is rotated around, the claw portion 20 engages with the reverse rotation prevention claw 15, and thus the rotation is suppressed.
When the cap 5 is further rotated counterclockwise from this engaged state, the connecting member 19 is broken, the cap 5 and the ring member 18 are separated, and only the ring member 18 remains in the mouth portion 11. Only the cap 5 can be detached from the mouth portion 11.

The control means 8 will be described. First, an encoder 21 connected between the control means 8 and the servo motor 7 is connected to the rotating portion of the servo motor 7 and outputs a pulse signal as a rotation position signal. An ammeter 22 for detecting the current output from the motor 7 is provided.
On the other hand, the control means 8 receives a pulse signal from the encoder 21 and detects the rotational position of the servo motor 7 to detect the rotational position of the servo motor 7 and a capping position connected to the ammeter 22. A torque detector 24 that detects torque acting on the head 6 is provided.
The rotational position and torque detected by the rotational position detection unit 23 and the torque detection unit 24 are transmitted to a comparison unit 25 as a comparison unit at predetermined time intervals.
The comparison unit 25 includes a torque storage unit 26 as a torque storage unit that temporarily stores the detected torque, a rotational position storage unit 27 as a rotational position storage unit that temporarily stores the detected rotational position, A set value storage unit 28 serving as a set value storage means in which maximum torque detection start torque a and determination value b, which will be described later, are stored is connected.
The comparison unit 25 transmits data necessary for control to the command unit 29 that controls the servo motor 7 while repeating transmission with the torque storage unit 26 and the rotational position storage unit 27. Thus, the servo motor 7 is driven.
In the present embodiment, the command unit 29 rotates the servo motor 7 at a constant rotational speed and a constant drive torque from the start to the end of capping.
Then, the control means 8 displays a graph as shown in FIG. 4 on a display device (not shown) based on the torque and rotation angle detection results obtained from the torque detection unit 24 and the rotation angle detection unit 23. .

Hereinafter, control of the capping apparatus 1 by the control means 8 will be described using the detection result shown in FIG. 4, the horizontal axis indicates the rotation angle of the capping head 6, and the vertical axis indicates the torque acting on the capping head 6. In FIG. 4, the tip of the screw portion 16 of the cap 5 and the mouth portion 11 are illustrated. The state after the front-end | tip of the screw part 14 is screwed is shown.
First, the detection result will be described. When capping is started and the screw portion 16 of the cap 5 and the screw portion 14 of the mouth portion 11 are screwed together, the cap 5 starts to descend while rotating, and these screw portions 14 , 16 generates a torque due to friction.
Further, when the cap 5 is lowered, the claw portion 20 of the ring member 18 comes into contact with the reverse rotation prevention claw 15 of the mouth portion 11 to increase the torque, and at the moment when the claw portion 20 gets over the reverse rotation prevention claw 15, the initial maximum torque is reached. Is detected.
After that, the torque decreases, but the claw portion 20 and the reverse rotation prevention claw 15 are provided at equal intervals, so that the claw portion 20 comes into contact with the reverse rotation prevention claw 15 again to increase the torque. A maximum appears. Since the claw portion 20 and the reverse rotation prevention claw 15 are provided at equal intervals, the maximum torque is generated at equal intervals thereafter, and the range where the claw portion 20 and the reverse rotation prevention claw 15 come into contact with each other as the rotation angle increases. As the torque increases, the maximum detected torque also increases.
Although not shown, when the detected torque reaches the tightening end torque stored in the set value storage unit 28 in advance, the rotation of the capping head 6 is stopped and the capping is ended.

Next, the control by the actual control means 8 will be described. At first, after the capping is started, the new torque received by the comparison unit 25 via the torque detection unit 24 is stored in the set value storage unit 28. This is compared with the stored maximum torque detection start torque a, and is repeated until a newly detected torque is detected exceeding the maximum torque detection start torque a.
The maximum torque detection start torque a is a value obtained by sampling in advance, and is set to be a torque between the maximum of the first torque and the maximum of the second torque shown in FIG. .
This is because the initial contact range between the claw portion 20 and the reverse rotation prevention claw 15 is very narrow, and the maximum torque may not be detected depending on the processing accuracy of the cap. While preventing the detection, it is set for the purpose of reducing the load of the memory capacity of the torque storage unit 26 and the rotational position storage unit 27.
Therefore, if the memory capacity of the torque storage unit 26 or the rotation position storage unit 27 has a margin, the maximum torque detection start torque a need not be set.

When the new torque received in the comparative capital 25 exceeds the maximum torque detection start torque a, the comparison unit 25 stores this torque in the torque storage unit 26 as the maximum torque, and the rotational position when the maximum torque is detected. The pulse value sent from the detection unit 23 is stored in the rotational position storage unit 27.
When the next new torque is detected, the comparison unit 25 compares this new torque with the maximum torque stored in the torque storage unit 26, and if the new torque is larger than the maximum torque, the new torque is updated. Torque is stored in the torque storage unit 26 as the maximum torque, and the pulse value sent from the rotation position detection unit 23 when the maximum torque is detected is stored in the rotation position storage unit 27.
When the new torque detected thereafter becomes smaller than the maximum torque, the comparison unit 25 calculates the difference between the new torque and the maximum torque, and this difference is compared with the determination value b stored in the set value storage unit 28. Compare.
When the difference is smaller than the determination value b, the maximum torque and the pulse value stored in the torque storage unit 26 and the rotational position storage unit 27 are continuously stored as they are.
When the difference between the new torque and the maximum torque becomes larger than the determination value b, the comparison unit 25 determines that the maximum torque stored in the torque storage unit 26 is the torque at the maximum of the torque, and further stores the rotational position. The pulse value stored in the unit 27 is determined as a winding tightening reference position c that serves as a reference for detecting the angle of the capping head 6.
If the determination value b is set larger than the difference between the maximum torque detected first and the torque detected when the torque increases again, the maximum torque detection start torque a is not set. In any case, the maximum of the initial torque is not determined as the winding reference position c.

Thereafter, the torque and the pulse value are transmitted to the comparison unit 25 every predetermined time interval. However, after the winding tightening reference position c is determined, the new torque is stored in the torque storage unit 26. It is not compared with the maximum torque that is present, but is compared with the winding tightening end torque stored in the set value storage unit 28.
Thereafter, when the new torque reaches the tightening end torque, the comparison unit 25 instructs the command unit 29 to end capping, and at the same time, the pulse value at the winding tightening reference position c stored in the rotational position storage unit 27 and the winding value. A rotation angle of the capping head 6 rotated from the winding reference position c to the end of winding is calculated from the pulse value when the tightening end torque is reached.
The comparison unit 25 compares the rotation angle of the capping head 6 from the winding tightening reference position c to the end of winding with the winding end angle stored in the set value storage unit 28, so that the capping is completed normally. Determine whether or not.
Here, the above-described winding tightening angle refers to the rotation angle of the capping head 6 from the winding tightening reference position c obtained in advance by sampling to the end of winding tightening. When it is within a predetermined range with respect to the winding end angle, it is determined that the capping has ended normally.
On the other hand, when the detected rotation angle deviates from the predetermined range with respect to the above-described winding fastening end angle, the comparison unit 25 determines that capping has not been performed normally, and the corresponding container in the subsequent process. Will be rejected.

As described above, when the claw portion 20 of the cap 5 first gets over the reversal prevention claw 15 of the mouth portion 11, the claw portion 20 and the reversal prevention claw 15 come into contact with each other at a constant interval. The rotation position of the capping head at the moment of overcoming, that is, when the maximum torque is generated is defined as the winding reference position c.
That is, according to the present embodiment, the processing accuracy of the claw portion 20 and the reverse rotation prevention claw 15 is low, and even if the torque detected for each cap 5 or container 2 varies, the fixed winding reference position c is detected. can do.
For this reason, the rotation angle of the cap 5 at the time of capping can be detected with high accuracy by comparing the rotation angle of the capping head 6 from the winding reference position c to the end of winding. .

In the above embodiment, when the winding tightening reference position c is detected, the cap 5 is rotated until a predetermined winding tightening torque is detected thereafter. In this way, it is possible to determine the end of the tightening of the cap 5.
For example, the additional winding tightening angle is stored in the set value storage unit 28, and when the winding tightening reference position c is detected, the control means 8 rotates the servo motor 7 by the additional winding tightening angle to It is also possible to perform winding tightening.
This additional tightening angle is also a value obtained by sampling in advance as with the above-described tightening end torque, and even if the processing accuracy of the claw portion 20 and the reverse rotation prevention claw 25 is low, The additional winding angle until the end of winding is constant for each cap 5.
Therefore, if this additional winding angle is used, the cap 5 can be tightened at a predetermined rotation angle even if the torque detected every time capping is performed.
Furthermore, in the above embodiment, the winding reference position c is detected from the maximum torque detected in the second. However, the present invention is not limited to this, and the winding reference position c is determined from the third and subsequent torque maximums. It may be detected. If the processing accuracy of the cap 5 and the container 2 is high, the winding reference position c may be detected from the maximum of the initial torque.

Next, the second embodiment will be described. As described above, the torque detected for each capping changes depending on the processing accuracy of the cap 5 and the container. In addition, for example, the capping head 6 and the servo motor 7 An error also occurs in the detected torque due to the frictional resistance generated by the meshing of the gears interposed between them.
That is, the torque output from the capping head 6 is the sum of the frictional resistance between the cap 5 and the container 2 and the frictional resistance of the capping head 6. The frictional resistance of each capping head 6 is different. It is what happens.
If this is shown in FIG. 5, the detection result shown with a broken line or a dashed-dotted line other than the detection result shown with the continuous line in the figure is obtained. Here, it is very difficult to set the maximum of the initial torque so as not to reach the winding tightening reference position c using the constant maximum torque detection start torque a as in the above embodiment.
That is, if a certain maximum torque detection start torque a is used as in the above-described embodiment, the maximum torque detection start torque is detected before the maximum of the first torque is detected as shown by the broken line in the figure. Torque exceeding a will be detected.
In the detection result of the broken line, when the torque reduced from the maximum of the first torque is reduced below the determination value b, the rotation angle corresponding to the maximum of the first torque is recognized as the reference tightening angle c. It becomes.
For this reason, the rotation angle of the capping head detected from the reference winding tightening angle c to the tightening end torque is excessively detected as compared with other detection results, and is actually normally capped. However, the container is treated as a defective product.

Therefore, in this embodiment, every time capping is performed, an appropriate maximum torque detection start torque a corresponding to the detected torque is calculated, so that the winding tightening reference position c can be detected with higher accuracy.
First, in the present embodiment, the comparison unit 25 stores the torque detected at an arbitrary rotational position from when capping is started until the maximum of the first torque is detected as the fluctuation torque d.
Here, at the arbitrary rotational position at which the fluctuation torque d is detected, capping is started and the tip of the screw portion 16 of the cap 5 and the tip of the screw portion 14 of the container 2 are engaged, and the claw portion 20 is reversed from there. It is desirable to detect until the prevention claw 15 comes into contact. In that section, there is little frictional resistance generated when the screw part 16 of the cap 5 and the screw part 14 of the container 2 are tightened, and the torque output from the capping head 6 is only the frictional resistance of the capping head 6. Because.
The comparison unit 25 adds the fixed torque value e stored in advance in the set value storage unit 28 to the fluctuation torque d, thereby calculating the maximum torque detection start torque a. A different maximum torque detection start torque a can be set for each detection result.
Therefore, since the detection of the winding reference position c is performed with high accuracy and the rotation angle is not excessively detected, the rotation angle of the cap 5 at the time of capping is detected with high accuracy. Can do.

Next, a third embodiment according to the present invention will be described. In this embodiment, the cap 105 in which the claw portion 20 is not formed is capped on the ring member 18 by using the same capping device 1 as in the above embodiment. The case will be described.
Since the capping device 1 of the present embodiment is the same as the capping device 1 of the first embodiment, detailed description thereof will be omitted, and the cap 105 and the container 102 will be described below with reference to FIG.
Also in the present embodiment, a screw portion 114 that is screwed into the cap 105 is formed in the mouth portion 111, and a flap locking portion that engages a flap 120 of a ring member 118 (described later) provided on the cap 105 below the mouth portion 111. A groove 115 is formed.
Next, a screw portion 116 that is screwed with the screw portion 114 of the mouth portion 111 is formed on the inner peripheral surface of the cap 105, and the container 102 is sealed by fitting into the opening of the mouth portion 111 on the upper surface of the cap 105. An inner ring 117a and an outer ring 117b are formed.
The inner ring 117 a is formed higher than the outer ring 117 b, and the tip of the inner ring 117 a is formed to be slightly inclined toward the outer peripheral side of the cap 5, and the tip of the outer ring 117 b is formed inside the cap 5. It is formed to be slightly inclined toward the circumferential side.

Further, the cap 105 of the present embodiment also includes a ring member 118, and in this embodiment, the ring member 118 is connected to the cap 105 by a breakable connecting member 119.
A flap 120 that engages with the flap locking groove 115 is formed on the inner peripheral surface of the ring member 118, and the flap 120 is deformed toward the inner peripheral surface of the ring member 118 during the tightening of the cap 105. It is supposed to be.
At the end of the tightening of the cap 105, the flap 120 is restored to its original shape, and the tip of the flap 120 is engaged with the flap locking groove 115.
For this reason, in order to open the cap 105 in this embodiment, the connecting member 119 is broken by rotating the cap 105 counterclockwise while the flap 120 is locked in the flap locking groove 115. Then, only the cap 105 is detached upward.

Then, when capping is performed by rotating the cap 5, the cap 105 descends and the inner peripheral surface of the mouth portion 111 first contacts the tip of the inner ring 117a, and the inner ring 117a is deformed while the mouth portion is deformed. The inner periphery of 111 is fitted.
When the cap 5 is further lowered, the tip of the outer ring 117b comes into contact with the outer periphery of the mouth part 111, and the outer ring 117b is also deformed to fit into the outer periphery of the mouth part 111. After the cap contacts the top surface of the cap, the cap 105 is further tightened by further rotating the cap 5.

FIG. 7 shows a graph represented by the control means 8 when the cap 105 as described above is capped. As in FIG. 4, the horizontal axis represents the rotation angle and the vertical axis represents the torque. .
First, when the cap 105 is lowered while rotating and the inner ring 117a comes into contact with the mouth portion 111, the torque increases. When the inner ring is completely fitted into the mouth portion 111, the maximum torque is reached. Detected.
Thereafter, the torque is once reduced, and when the cap 5 is further lowered and the outer ring 117b comes into contact with the mouth portion 111, the torque is increased again. Thereafter, when a predetermined tightening end torque is detected, the capping is ended.
Then, in the same procedure as in the first embodiment, the control means 8 detects the maximum torque generated when the inner ring 117b is fitted into the mouth 111, and the new torque detected thereafter is the maximum torque. When the maximum torque detected in (1) is smaller than the determination value b, the winding tightening reference position c is detected from the pulse value corresponding to the maximum torque.
Thereafter, as in the first embodiment, capping is performed until a predetermined tightening end torque is detected, and the capping quality is determined using the rotation angle from the winding reference position c to the end tightening angle. Judging.
Here, if there is no decrease in torque more than the judgment value b from the first peak value, there is a possibility of processing failure of the cap 105, so the comparison unit 25 of the control means 8 causes the container 102 of the cap 105 to Is rejected in a later process.

Thus, since the rotation position of the capping head when the maximum torque generated when the inner ring 117b is fitted to the mouth portion 111 is detected is the winding tightening reference position c, as in the first embodiment, Even if the torque detected for each cap 105 varies, the quality of capping can be determined with high accuracy.
In addition to this embodiment, as described above, when the winding reference position c is detected, capping may be performed using an additional winding angle, or the winding reference position c may be detected. The maximum torque detection start torque a may be used.
As for the maximum torque detection start torque a, as shown in the second embodiment, the maximum torque detection start torque a may be calculated using a variable torque d and a fixed torque.

Schematic which shows the capping apparatus concerning a present Example. The expanded sectional view about the mouth part of the cap and container in 1st Example. The perspective view of a cap explaining the nail | claw part of a cap. The figure which shows the relationship between the rotation angle detected in a 1st Example, and a torque. The figure which shows the relationship between the rotation angle detected in a 2nd Example, and a torque. The expanded sectional view about the mouth part of the cap and container in a 3rd Example. The figure which shows the relationship between the rotation angle detected in a 3rd Example, and a torque.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capping apparatus 2 Container 5, 105 Cap 6 Capping head 7 Servo motor 8 Control means 11, 111 Mouth part 15 Reverse rotation prevention claw 20 Claw part 117a Inner ring 117b Outer ring a Maximum torque detection start torque b Judgment value c Winding reference position d Fluctuating torque e Fixed torque

Claims (10)

In the capping method for tightening the cap while detecting the torque acting on the capping head,
The detected maximum torque and the rotational position of the capping head at that time are stored, and when the difference between the stored maximum torque and the newly detected torque is equal to or greater than a predetermined determination value, the maximum torque is A capping method characterized by detecting a rotation angle from the winding reference position to the end of winding using the rotation position of the capping head when detected as a winding reference position.   A predetermined torque set in advance is set as the maximum torque detection start torque, and the winding tightening reference position is detected from the maximum torque detected beyond the maximum torque detection start torque. The capping method according to claim 1.   The maximum torque detection start torque is calculated from a fluctuating torque value detected from when the cap screw and the container screw are engaged until the torque becomes stable, and a preset fixed torque value. The capping method according to claim 2.   When the winding tightening reference position is detected, capping is performed until a preset tightening torque is reached, and the rotation angle of the capping head from the winding tightening reference position to the end of tightening is set to a predetermined winding torque. The capping method according to any one of claims 1 to 3, wherein the quality of the capping is determined by comparing with a fastening end angle.   The cap is tightened by stopping the rotation of the capping head after the capping head is further rotated by a predetermined additional tightening angle when the winding tightening reference position is detected. The capping method according to claim 3. In a capping device that includes a capping head that holds a cap, a servo motor that rotationally drives the capping head, and a control unit that controls the servo motor, and tightens the cap around the container while detecting torque acting on the capping head.
Torque storage means for storing detected torque, comparison means for comparing the difference between the stored torque and the newly detected torque, rotational position detection means for detecting the rotational position of the capping head, and torque Rotational position storage means for storing the rotational position signal when detected, and a set value storage unit for storing a required set value,
When the newly detected torque is greater than the torque stored in the torque storage means, the comparison means stores the newly detected torque as the maximum torque in the torque storage means, and sets the maximum torque to the maximum torque. Store the corresponding position signal in the rotational position storage means,
When the newly detected torque is smaller than the determination value stored in the set value storage unit than the maximum torque stored in the torque storage means, the rotational position of the capping head stored in the rotational position storage means is determined. A capping device that determines a rotation reference position and detects a rotation angle from the winding reference position to the end of winding.   A predetermined torque set in advance is set as the maximum torque detection start torque, and the comparison means detects the winding tightening reference position using the determination value from the maximum torque detected exceeding the maximum torque detection start torque. The capping device according to claim 6.   The set value storage means stores a predetermined torque as a fixed torque value, and the comparison means sets the fluctuation torque value detected from when the cap screw and the container screw are engaged until the torque is stabilized to The capping device according to claim 7, wherein the maximum torque detection start torque is calculated by adding a fixed torque value.   The comparison means rotates the capping head until the winding tightening torque stored in the set value storage means is detected, and determines the rotation angle of the capping head from the winding tightening reference position to the end of winding. The capping device according to any one of claims 6 to 8, wherein a capping quality is determined by comparing with a winding tightening end angle stored in a set value storage means.   The said comparison means performs the cap tightening by rotating a capping head further by the additional winding tightening angle memorize | stored in the said setting value memory | storage means from the said winding tightening reference position. The capping device according to claim 8.

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