JP4438415B2 - Capping method and capping device - Google Patents

Description

  The present invention relates to a capping method and a capping device for driving a capping head by a motor and tightening a cap around a container, and more specifically, monitoring a torque acting on a motor driving the capping head and winding the cap based on the monitored torque. The present invention relates to a capping method and a capping device for fastening.

Conventionally, a capping method is known in which a torque acting on a motor that drives a capping head is monitored and a cap is tightened based on the monitored torque. For example, when the monitored torque reaches a predetermined final tightening set torque. A capping method for ending capping is known. (Patent Document 1)
JP 2003-81387 A

Here, the rotational drive of the motor is normally transmitted to the capping head via a transmission mechanism such as a speed reducer and a gear. In addition to the friction loss caused by the meshing of the gear in the transmission mechanism, the capping head Friction loss also occurs in the rotating sliding part of the rotating shaft of the motor, so there is a difference between the magnitude of the torque actually acting on the motor as the monitor torque and the magnitude of the actual torque actually acting on the cap. There is an error.
Due to this error, it is not possible to know the torque actually acting on the cap simply by monitoring the monitor torque. Even if the monitor torque reaches the final tightening set torque, the cap is wound with a truly appropriate torque. It was unclear whether it was tightened or not, and it was difficult to say that accurate capping was performed.
In addition, in the case of a capping device provided with a plurality of capping heads, there is a problem that the actual torque acting on the cap differs between the capping heads even if the same torque is commanded because the friction loss is different in each capping head. In view of such problems, the present invention provides a capping method that enables capping with high accuracy by obtaining an actual torque actually acting on the cap from the above error.

That is, according to the capping method of claim 1, in the capping method of monitoring the torque acting on the motor that drives the capping head and tightening the cap based on the monitor torque.
A plurality of the capping heads are provided, and for each capping head , an error between the magnitude of the monitor torque and the magnitude of the actual torque that actually acts on the cap corresponding thereto is obtained in advance . The capping is performed based on the actual torque obtained by correcting each error for each capping head .

The capping device according to claim 9 includes a capping head for holding the cap, a motor for rotationally driving the capping head, and a control means for controlling the motor, and torque acting on the motor for driving the capping head. In the capping device that monitors the cap and winds the cap around the container based on the monitor torque,
The control means is provided with a storage unit for storing an error between the magnitude of the monitor torque and the actual magnitude of the actual torque acting on the cap corresponding to the monitor torque, and the control means stores the error stored in the storage unit. It is characterized by capping based on the actual torque obtained by correcting.

According to the above-mentioned capping method and capping device, an error between the magnitude of the monitor torque and the actual magnitude of the actual torque that actually acts on the cap is obtained in advance, and the capping is performed using the actual torque. .
For this reason, since the torque actually acting on the cap during capping can be known, it is possible to perform capping with an appropriate torque, and capping can be performed with higher accuracy than in the past.

FIG. 1 shows a capping device 1 according to the present invention, and FIG. 1 shows a mounting table 3 on which a container 2 is mounted and a neck for supporting the container 2 mounted on the mounting table 3. The gripper 4 is composed of a capping head 6 that winds the cap 5 around the container 2 from above the mounting table 3, and a servo motor 7 that drives the capping head 6. The capping device 1 is controlled by a control means 8. To be controlled.
In such a capping device 1, after the container 2 on the mounting table 3 is supported by the neck gripper 4, the capping head 6 is lowered to engage the cap 5 with the mouth 11 of the container 2, and the servo motor 7 Capping is performed by rotating the cap 5 by driving.

The container 2 and the cap 5 will be described. FIG. 2 is an enlarged view of the mouth portion 11 of the container 2 and the cap 5 wound around the mouth portion 11.
The mouth portion 11 of the container 2 is provided above the main body portion 12, and a screw portion 13 to be screwed with the cap 5 is formed.
On the other hand, the cap 5 is made of resin and has a bottomed cylindrical shape, and a screw portion 14 that is screwed with the screw portion 13 of the mouth portion 11 is formed on the inner peripheral surface thereof. 11 is formed between the outer ring 15a and the inner ring 15b. The outer ring 15a is fitted between the outer ring 15a and the inner ring 15b. A buffer portion 15c is formed.

Next, FIG. 3 shows a cross-sectional view of the capping head 6 in this embodiment. A plurality of capping heads 6 are attached to two rotating bodies 21 positioned above and below at equal intervals in the circumferential direction. At the same time, it moves in a certain rotational direction.
The capping head 6 holds the spindle 23 driven by the servo motor 7 via the speed reducer 22, a chuck 6 a (see FIG. 1) that holds the cap 5 and rotates integrally with the spindle 23, and the spindle 23. And an elevating mechanism 24 that elevates and lowers the chuck 6a.
The servo motor 7 is fixed from the upper rotating body 21 with the output shaft 7a facing downward, and the output shaft 7a is provided with a sun gear 22a constituting a speed reducer 22.
The speed reducer 22 includes a plurality of planetary gears 22b provided around the sun gear 22a, a fixed gear 22c provided on the outer periphery of the planetary gear 22b and fixed to the upper rotating body 21, and a planetary gear 22b. The carrier 22d rotates by itself while being rotatably held.
Such a planetary gear mechanism is conventionally known and will not be described in detail. However, the servomotor 7 rotates the sun gear 22a so that the carrier 22d rotates at a speed ratio set in the speed reducer 22. It has become.

The spindle 23 is provided below a spline shaft 26 connected to the lower side of the carrier 22d and a spline cylinder 27 surrounding the outer periphery of the spline shaft 26. The outer periphery is surrounded by a support member 29 and is supported by the support member 29. A pipe 30 surrounding the spline cylinder 27 is provided above the member 29.
Key grooves 26a and 27a are formed in the outer periphery of the spline shaft 26 and the inner periphery of the spline tube 27, respectively. The spline tube 27 moves up and down in the vertical direction while rotating integrally with the spline shaft 26 in the horizontal direction. The spindle 23, the support member 29, and the pipe 30 are also raised and lowered integrally by raising and lowering the spline cylinder 27.
The elevating mechanism 24 includes an upper housing 31 that rotatably holds the upper portion of the spline cylinder 27, a lower housing 32 that surrounds the upper housing 31 and rotatably holds the support member 29 from below, and the rotation. An elevating member 34 for elevating the lower housing 32 along a guide 33 provided between the bodies 21 is provided, and the upper housing 31 and the lower housing 32 are coupled to each other by screws.
A spring 37 is elastically mounted between the lower end of the upper housing 31 and the step formed on the inner peripheral surface of the lower housing 32 via a bearing 36 that engages with the step. When the pipe 30 rises relative to the lower housing 32 together with the spindle 23, the upper end of the pipe 30 comes into contact with the lower surface of the bearing 36, and the pipe 30 is urged downward by the spring 37. .
Further, the elevating member 34 is provided with a cam follower 38 that engages with a groove cam (not shown) formed inside the moving path of the capping head 6 to elevate the elevating member 34, and the lower housing 32 moves up and down together with the cam follower 38. To do.

The control means 8 will be described with reference to FIG. 1. The servo motor 7 is controlled by the encoder 41 for transmitting the rotational position of the servo motor 7 as a pulse signal, and the servo motor 7 is controlled. An amplifier 42 for detecting the torque to be rotated and the rotation speed at that time is provided.
The pulse signal from the encoder 41 is received by the rotational position detector 43 provided in the control means 8, and the torque and rotational speed detected by the amplifier 42 are monitored by the torque / rotational speed detector 44 and the actual rotational speed. As monitored.
Further, the monitor torque and the actual rotation speed monitored by the torque / rotation speed detection unit 44 are transmitted to the torque correction unit 45, and the torque correction unit 45 is received from the storage unit 46 connected to the torque correction unit 45. The actual torque corresponding to the monitor torque and the actual rotational speed is read out.
Although this actual torque will be described in detail later, it means the torque actually acting on the cap 5 at the time of capping, and is stored in the storage unit 46 in advance by experiment.
The data of the rotational position detection unit 43 and the torque correction unit 45 are respectively transmitted to the control unit 47, which determines the capping state from the received data and is necessary for the subsequent control of the servo motor 7. The command torque and the command rotation speed are transmitted to the amplifier 42.
Then, the control means 8 converts the monitor torque and actual rotation speed monitored by the torque / rotation speed detection unit 44 and the actual torque read by the torque correction unit 45 into a graph which will be described below, and displays it on a display device (not shown). It is supposed to be displayed.

Hereinafter, the actual torque will be described. In the case of the capping head 6 having the above-described configuration, there is a difference between the monitor torque monitored by the torque / rotation speed detector 44 and the actual torque actually acting on the cap 5. An error has occurred.
As this error, it is conceivable that the gears in the speed reducer 22 provided in the capping head 6 are engaged with each other and a loss torque generated when the support member 29 rotates in the lower housing 32.
In other words, the monitor torque monitored by the torque / rotation speed detector 44 is the torque acting on the servo motor 7 via the capping head 6, and the actual torque received from the cap 5 by tightening the cap 5. The sum of the torque and the loss torque received from the inside of the capping head 6 due to the friction loss described above.

In this embodiment, the actual torque is obtained by experiments. As shown in FIG. 4, a magnet clutch 51 is attached to the tip of the capping head 6 instead of the cap 5, and the actual torque is measured. Yes.
The magnet clutch 51 itself is well known in the art and will not be described in detail. However, when a torque greater than the load torque set in the setting means 52 is applied from the capping head 6, the magnet clutch 51 is disengaged. To rotate.
Then, a predetermined load torque is set in the setting means 52, and in this state, the control unit 47 instructs the servo motor 7 to rotate at a predetermined command torque and a command rotational speed.
When the command torque is higher than the load torque, the magnet clutch 51 starts to rotate with the load torque applied to the capping head 6, and the torque / rotation speed detector acts on the servo motor 7 via the amplifier 42. The monitor torque and the actual rotation speed are detected.
Since the load torque set at this time is the same as the torque acting on the cap 5 as it is, the storage unit 46 stores the monitor torque and the actual rotational speed at this time, and stores the load torque at that time as the actual torque. .

More specifically, for example, when commanding the command torque 300 N · cm and command rotation speed 300 rpm to the amplifier 42 and setting the load torque of the magnet clutch 51 to 100 N · cm, the torque / rotation speed detection unit 44, when the monitor torque 160 N · cm and the actual rotational speed 300 rpm are detected, the storage unit 46 indicates that the actual torque when the monitor torque 160 N · cm and the actual rotational speed 300 rpm are detected is 100 N · cm. Remembered.
If the load torque is subtracted from the monitor torque, the loss torque in the capping head 6 at that time is calculated. Therefore, the storage unit 46 may store the loss torque instead of the actual torque. In this case, the loss torque in the above example is 60 N · cm.
Thus, the monitor torque and the actual rotational speed are detected while changing the setting of the load torque by the setting means 52 and the command rotational speed of the servo motor 7 from the amplifier 42, and the monitor as shown in FIG. The actual torque for each torque and actual rotational speed is stored in the storage unit 46.
FIG. 5 is a three-dimensional graph showing the actual rotational speed on the horizontal axis, the monitor torque in the depth direction, and the actual torque in the height direction. It is expressed as a curved surface by calculation.
According to this graph, if the monitor torque and the actual rotation speed are detected, the actual torque at that time is obtained. For example, when the actual rotation speed is 100 rpm and the monitor torque is 250 N · cm, the actual torque is detected. If a straight line is drawn vertically upward from the intersection A obtained on the plane based on the rotation speed and the monitor torque, the curved surface intersects and the intersection B becomes the actual torque.

Hereinafter, capping using the capping device 1 will be described using a graph relating to the monitor torque and the actual rotational speed shown in FIG.
FIG. 6A shows a graph regarding the command torque and the command rotational speed of the servo motor 7 by the amplifier 42, and FIG. 6B shows a graph regarding the monitor torque and the actual rotational speed detected by the amplifier 42. The horizontal axis indicates the elapsed time required for capping.
In the present embodiment, the period from the start to the end of capping is divided into three periods of a meshing period, a temporary tightening period, and a final tightening period. Before the meshing period starts, the capping head 6 The cam follower 38 is located at the lower end together with the lower housing 32 according to the groove cam.
At this time, the cap 5 held by the chuck 6a is in contact with the mouth 11 of the container 2 so as not to move further downward, but is biased downward by the elastic force of the spring 37. It has become.

When the control unit 47 instructs the amplifier 42 to start the servo motor 7 from this state, the servo motor 7 starts rotating according to a predetermined command rotation speed and a specified torque set in advance, and the meshing period starts.
Since the servo motor 7 is stopped at the start of the meshing period, the actual rotation speed and the monitor torque increase from zero, and then the actual rotation speed reaches the command rotation speed.
On the other hand, regarding the monitor torque, since the screw portion 14 of the cap 5 is not screwed into the screw portion 13 of the mouth portion 11 at the initial stage of the meshing period, almost no actual torque is generated and is detected at this time. The monitored torque is a torque required to accelerate the loss torque of the capping head 6 and the rotary inertia body such as the spindle 23 to a predetermined speed.
Thereafter, when the cap 5 rotates and the caps 5 and the tips of the screw portions 13 and 14 of the mouth portion 11 come into contact with each other, the monitor torque increases momentarily and decreases immediately thereafter. Then, the monitor torque increases again as the screwing of both screw portions 13 and 14 progresses.
In parallel with this, in the control means 8, the monitor torque and the actual rotational speed are transmitted from the torque / rotational speed detector 44 to the torque corrector 45 every predetermined time. The actual torque corresponding to the actual rotational speed is read from the storage unit 46.
In this embodiment, the meshing period is set according to the elapsed time of capping. Specifically, the period from when the servo motor 7 starts to rotate until at least one rotation of the cap 5 is defined as the meshing period.
This is because the orientation of the cap 5 held by the chuck 6a and the orientation of the container 2 placed on the placing table 3 are different each time capping is performed, and each time the capping is performed, the screw portion 14 and the mouth of the cap 5 are separated. This is because the timing at which the screw portion 13 of the portion 11 is fitted to each other varies.

When the above-described predetermined time has elapsed and the meshing period ends, the process proceeds to the temporary fastening period. In this embodiment, capping is performed while maintaining the command rotational speed and the command torque as they are even during the meshing period.
During this temporary fastening period, the cap 5 rotates and the screwing of the screw part 14 of the cap 5 and the screw part 13 of the mouth part 11 increases, and the inner ring 15 b of the cap 5 contacts the mouth part 11 of the container 2. Then, the monitor torque rapidly increases during the period from when it is fitted, and when the inner ring 15b is completely fitted thereafter, the monitor torque is reduced.
Thereafter, when the cap 5 further rotates and the tip of the mouth portion 11 comes into contact with the buffer portion 15c, the torque increases again. When the buffer portion 15c is compressed to some extent and the actual torque reaches a predetermined temporary tightening end torque, End the tightening period.
This temporary fastening end torque is a torque obtained in advance by experiments, and is a torque not including the loss torque as described above.
At this time, since the actual torque acting on the cap 5 at that time is read from the monitor torque acting on the servo motor 7 and the actual rotational speed, the temporary tightening end torque acting on the cap 5 is increased. It can be detected with accuracy.

When the temporary tightening period ends as described above, the process proceeds to the final tightening period, and the control unit 47 decelerates the command rotational speed of the servo motor 7 to the amplifier 42 and tightens the command torque to a predetermined tightening time. Decrease to end command torque.
The tightening end command torque is obtained by determining the actual tightening end torque that acts on the cap 5 when the cap 5 is actually tightened, and the rotational speed of the capping head 6 is zero based on the actual tightening end torque. The monitor torque at this time is also calculated by back calculation, and this monitor torque is used as the tightening end command torque.
In the final tightening period, as the end of the winding tightening is approached, the buffer portion 15c of the cap 5 is compressed by the mouth portion 11, and the monitor torque approaches the above-described winding tightening end command torque. The speed gradually decreases.
At the same time as the actual torque reaches the actual tightening end torque, the monitor torque reaches the end tightening command torque, and the actual rotational speed becomes zero.
Thereafter, the capping is stabilized by continuously applying the actual tightening torque to the cap 5 for a predetermined time. When the predetermined time has elapsed, the capping is completed.
Then, the cam follower 38 of the capping head 6 moves up with the lower housing 32 according to the groove cam, the chuck 6a is detached from the cap 5, and the container 2 is conveyed to the subsequent process.

In this embodiment, the torque value of the temporary fastening end torque is also set as the angle detection start torque. When the angle detection start torque is detected, the control unit 47 simultaneously shifts to the final fastening period. Then, measurement of the rotational position of the capping head 6 detected by the rotational position detector 43 is started, and the rotational angle of the capping head 6 during the final fastening period is measured.
The rotation angle of the capping head 6 measured here is compared with the reference winding angle of the cap obtained in advance by experiments, and if the measured value is within a predetermined range with respect to the reference winding angle, the capping head 6 is capped. The container 2 is determined to be a non-defective product, and if it is outside the predetermined range, it is determined to be a defective product.

As described above, since capping is performed using the actual torque actually acting on the cap in this embodiment, high-precision capping can be realized.
On the other hand, in the above-mentioned Patent Document 1, capping is performed using a constant set tightening torque, and the loss torque due to the capping head is not taken into consideration.
Therefore, when the cap is tightened with the above-described set tightening torque, the cap is tightened excessively in the case of a capping head with a large loss torque, and the cap is tightened excessively in the case of a capping head with a small loss torque. As a result, the capping quality varies.
Further, even when the capping quality is determined from the rotation angle of the cap during the final tightening period, the actual cap tightening angle at the end of the temporary tightening period varies due to the difference in loss torque for each capping head 6. Therefore, an error occurs in the timing for starting the detection of the rotation angle.
In contrast, in this embodiment, the actual torque is used to detect the actual tightening torque, so that the cap 5 can be tightened with the same tightening force regardless of the difference in the capping head 6. Stable capping quality is obtained.
In addition, since the angle detection start torque is also detected using the actual torque, there is no error in the transition to the final tightening period for each capping head 6, so that the capping quality determination can be performed with higher accuracy. it can.

In the above embodiment, the actual torque is stored in the storage unit 46, but instead, the monitor torque and the loss torque for each actual rotational speed may be stored.
In this case, at the time of capping, the torque correction unit 45 reads the loss torque corresponding to the monitor torque and the actual rotation speed at that time, and calculates the value obtained by subtracting the loss torque from the monitor torque at that time as the actual torque. Thus, the same result as described above can be obtained.
In the above embodiment, the temporary tightening end torque and the angle detection start torque are set to the same torque, and the rotation angle of the capping head during the final tightening period is measured to determine whether the capping is good or not. The end torque and the angle detection start torque need not be the same torque. For example, a predetermined actual torque measured during the temporary fastening period may be used as the angle detection start torque.
Furthermore, in the above-described embodiment, the winding tightening end command torque is obtained by experiment. However, for example, this winding tightening end command torque may be the same as the command torque in the temporary tightening period. In this case, the capping is finished when the actual torque reaches the above-described tightening torque.

Next, as another embodiment of the present invention, capping may be performed by rotating the capping head 6 by the additional winding tightening angle stored in the control unit 47 from the time when the angle detection start torque is detected. .
Specifically, when the control unit 47 detects the angle detection start torque, the control unit 47 thereafter starts measuring the rotation angle of the capping head 6 based on a signal from the rotation position detection unit 43, and the rotation angle is previously tested. When the additional tightening angle obtained by the above is reached, the capping is terminated.
Also in this embodiment, since the angle detection start torque is detected using the actual torque, the additional winding angle does not vary for each capping head 6, and capping can be performed with high accuracy. it can.

As yet another embodiment, in the above embodiment, the storage unit 46 stores the respective relationships among the actual torque, the monitor torque, and the actual rotation speed. Even without using the clutch 51, it is possible to perform capping with higher accuracy than in the past.
Specifically, the capping head 6 is idled without attaching the magnet clutch 51, and the monitor torque applied to the servo motor 7 at that time is stored in the storage unit 46 as a loss torque as an error.
At this time, the rotational speed of the capping head 6 is changed, and the loss torque for each actual rotational speed of the capping head 6 is stored in the storage unit 46.
When actual capping is performed, the actual torque is calculated by subtracting the loss torque corresponding to the actual rotational speed from the monitor torque acting on the servo motor, and the above embodiment is based on this actual torque. The same capping is performed.
Thus, even if the loss torque is calculated without attaching the magnet clutch, the loss torque for each actual rotation speed generated in the capping head 6 can be detected. Therefore, the actual torque can be calculated based on the loss torque. Even with the calculation, it is possible to perform capping with higher accuracy than the conventional technique.

Schematic which shows the capping apparatus concerning a present Example. The expanded sectional view about the opening part of a cap and a container. Sectional drawing about a capping head. The schematic diagram when the magnet clutch is attached to the capping device. The graph which shows the relationship of the monitor torque memorize | stored in the memory | storage part, an actual rotational speed, and an actual torque. It is a graph which shows the state of capping, (a) shows the graph about command torque and command rotation speed, (b) shows the graph about real torque, monitor torque, and real rotation speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capping apparatus 2 Container 5 Cap 6 Capping head 7 Servo motor 8 Control means 22 Decelerator 45 Torque correction part 46 Storage part 51 Magnet clutch

Claims (10)

In the capping method for monitoring the torque acting on the motor that drives the capping head and tightening the cap based on the monitor torque,
A plurality of the capping heads are provided, and for each capping head , an error between the magnitude of the monitor torque and the magnitude of the actual torque that actually acts on the cap corresponding thereto is obtained in advance . A capping method, wherein capping is performed based on an actual torque obtained by correcting each error for each capping head . 2. The capping method according to claim 1 , wherein the error is obtained in accordance with the magnitude of the monitor torque and the magnitude of the rotational speed of the capping head. 3. The cap tightening is ended when the actual torque obtained by correcting the error becomes a predetermined tightening end torque. 4. Capping method. The tightening angle from when the actual torque obtained by correcting the above error reaches the predetermined angle detection start torque until the capping head rotation angle is measured and then the cap tightening is finished. 4. The capping method according to claim 3 , wherein the pass / fail judgment is performed based on whether or not the angle is within a required angle range. When the actual torque obtained by correcting the error reaches the predetermined angle detection start torque, the rotation angle of the capping head is measured, and when the capping head is rotated by a predetermined winding angle, The capping method according to claim 1, wherein the winding is terminated. 6. The capping method according to claim 5 , wherein the pass / fail judgment is made based on whether or not the magnitude of the actual torque when the cap tightening is finished is within a required torque range. Capping method according to any one of claims 6 to claims 1, characterized in that obtaining the error by measuring the monitor torque in a state in which the action of the actual torque of known magnitude to the capping head. The error is obtained from the magnitude of the monitor torque corresponding to the rotational speed of the capping head when the actual torque is zero, and the actual torque is obtained by calculation using the monitor torque and the error when capping. The capping method according to claim 2 , wherein: A capping head for holding the cap, a motor for rotationally driving the capping head, and a control means for controlling the motor are provided. The torque acting on the motor for driving the capping head is monitored, and the cap is placed on the basis of the monitored torque. In the capping device to wind
The control means is provided with a storage unit for storing an error between the magnitude of the monitor torque and the actual magnitude of the actual torque acting on the cap corresponding to the monitor torque, and the control means stores the error stored in the storage unit. A capping device that performs capping on the basis of an actual torque obtained by correcting the above. Claim the capping head is provided with a plurality, in the storage unit, wherein the error between the magnitude of the actual torque corresponding thereto and the size of the monitor torque for each capping head is stored 9. The capping device according to 9 .

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