JP7617362B2 - Capping Device - Google Patents

Description

The present invention relates to a capping device, and more specifically to a capping device that tightens and attaches a cap to a plastic container.

2. Description of the Related Art Conventionally, a capping device for attaching a cap to a resin container by winding and tightening it is known (for example, see Patent Document 1).
The capping device in Patent Document 1 is equipped with a capping head using a servo motor, and specifically, attaches a cap to the mouth of a container as follows: First, the chuck of the capping head holding the cap is lowered a required amount to place the cap over the mouth of the container, so that the lower end of the threaded portion of the cap abuts against the threaded portion of the mouth of the container, and when this state is reached, the cap is rotated via the chuck by the servo motor, thereby wrapping and attaching the cap to the mouth of the container.

JP 2002-308380 A

In the capping device of Patent Document 1, before the cap is tightened around the mouth of the container, the chuck holding the cap is lowered to the position of the mouth of the container, so that the lower end of the threaded part of the cap abuts on the threaded part of the container. At that time, the threaded part of the cap may jump over the threaded part of the container and fall onto the threaded part one step below, resulting in "thread drop". When this "thread drop" phenomenon occurs, there is a problem that the impact at that time causes the filling liquid in the container to splash out and adhere to the inner surface of the cap and the threaded parts of the cap and container, causing contamination.
In addition, as containers and caps have become lighter in recent years, the threaded portions of the caps and containers may not have sufficient strength, and if the above-mentioned "screw drop-out" occurs when attaching the cap, there is a problem that the threaded portions of the cap and container may be damaged.

In view of the above circumstances, the present invention provides a capping device comprising: a conveying mechanism for conveying containers; a capping head having a chuck for holding caps and for attaching caps to openings of containers conveyed by the conveying mechanism; a servo motor for rotating the chuck of the capping head; a lifting mechanism for raising and lowering the capping head; and a control device for controlling the operation of the servo motor and the conveying mechanism,
a capping head holding a cap by the chuck is lowered by the lifting mechanism, and the servo motor starts to rotate the chuck from a stopped state, thereby rotating the cap held by the chuck and wrapping and attaching it to the mouth of a container,
a speed detection mechanism for detecting a speed at which the container is conveyed by the conveying mechanism, and the speed at which the container is conveyed by the conveying mechanism detected by the speed detection mechanism is input to the control device ;
The control device includes:
when the container conveying speed by the conveying mechanism is switched between a high predetermined operating speed and an operating speed slower than the high predetermined operating speed, the rotation start timing of the servo motor is automatically switched in accordance with the conveying speed of the conveying mechanism,
When the conveying mechanism conveys the container at the predetermined operating speed, the rotation of the servo motor is started in a direction for fastening the cap while the chuck of the capping head is being lowered by the lifting mechanism and before the threaded portion of the cap held by the chuck comes into contact with the threaded portion of the container,
When the conveying mechanism conveys a container at an operating speed slower than the specified operating speed, the chuck of the capping head is lowered by the lifting mechanism, and the threaded portion of the cap held by the chuck comes into contact with the threaded portion of the container, and then the servo motor begins to rotate in the direction of tightening the cap .

With this configuration, the timing at which the servo motor starts to rotate can be changed according to the speed at which the container is transported by the transport mechanism. This reduces the impact when the threaded portion of the cap and the threaded portion of the container mouth come into contact and engage, allowing the cap to be attached to the container smoothly and reliably regardless of the transport speed of the container. This prevents the aforementioned "screw drop" from occurring, and prevents the inner surface and threaded portion of the cap from being contaminated by the filling liquid that has spilled out of the mouth of the container.

FIG. 1 is a plan view showing an embodiment of the present invention. FIG. 2 is a vertical cross-sectional view of a main portion of FIG. 1 . FIG. 2 is an enlarged view of a main part of FIG. 1 . 4A to 4C are side views showing the timing of the cap lowering and the cap starting to rotate at each position shown in FIG. 3 . FIG. 13 is a diagram showing the results of an experiment to compare the weight of the filling liquid adhered to the cap after completion of cap attachment using a conventional capping device and the capping device of the present invention.

The present invention will now be described with reference to the illustrated embodiment. In Figures 1 and 2, reference numeral 1 denotes a filling system, which includes a rotary filler 2 having a plurality of filling valves (not shown) arranged at equal pitches around its periphery, and a rotary capping device 4 having a plurality of capping heads 3 arranged at equal pitches around its periphery.
While the filler 2 and the capping device 4 are rotating in the direction of the arrow, an empty container 5 is supplied below each filling valve of the filler 2 by a supply wheel (not shown), and each container 5 is gripped by a gripper (not shown) provided on the filler 2 and filled with a predetermined amount of filling liquid by the filling valve. Each container 5 filled with filling liquid by the filling valve of the filler 2 is released from the gripper of the filler 2 and is transferred from the filler 2 to the capping device 4 via the intermediate wheel 6.

The capping device 4 has capping heads 3 which hold caps 8 by chucks 7 at equally spaced positions on the outer periphery, and has an open/close gripper 4A below each capping head 3 which grips the neck 5A of the container 5.
The container 5 delivered from the intermediate wheel 6 is filled with the filling liquid 9, and the liquid level 9A is located slightly below the flange 5B of the neck 5A. The container 5 is gripped on both sides of the neck 5A by the grippers 4A and supported by the flange 5B formed on the neck 5A, so that it can be transported at a predetermined height (see FIG. 2).
In addition, a threaded portion 5D is formed on the outer periphery of the mouth 5C of the container 5, while a threaded portion 8A is formed on the inner periphery of the cap 8, which is screwed into the threaded portion 5D of the container 5 (see Figures 2 and 4).
Furthermore, an inner ring 5E is formed between the flange portion 5B and the threaded portion 5D of the container 5, while a release ring 8B is provided at the lower end of the cap 8 (see Figures 2 and 4).

As the capping device 4 rotates in the direction of the arrow, the capping head 3 is lowered from the upper end to the lower end by the lifting mechanism 11, and the chuck 7 is rotated in the tightening direction at a predetermined timing by the servo motor 12 provided for each capping head 3, so that the cap 8 held by the chuck 7 is lowered and placed over the mouth 5C of the container 5, and then tightened and attached.
As will be described in more detail later, in this embodiment, when the capping device 4 is operated at or above a predetermined operating speed, the servo motor 12 is configured to start rotating and rotate the cap 8 at a point in the middle of the capping head 3 being lowered by the lifting mechanism 11, thereby suppressing the occurrence of the aforementioned ``screw drop-out'' and allowing the lower end 8A' of the threaded portion 8A of the cap 8 to smoothly engage with the threaded portion 5D of the container 5.
After the cap 8 has been attached to the container 5 by each capping head 3 of the capping device 4, the container 5 is then released from the gripper 4A at the neck 5A and is gripped by the discharge wheel 13 and discharged from the capping device 4 onto the discharge conveyor 14, and then transported by the discharge conveyor 14 downstream to a processing device not shown (see Figure 1).

The capping device 4 comprises a rotor 16 that rotates clockwise to transport the container 5, a plurality of capping heads 3 arranged at equal pitch in the circumferential direction of the outer periphery of the rotor 16, a lifting mechanism 11 that raises and lowers the capping heads 3 in a predetermined area in the rotational direction of the rotor 16, a gripper 4A arranged below the capping heads 3 to grip the neck 5A of the container 5, and a control device 17 that controls the drive source of the rotor 16 and the operation of each servo motor 12.
The rotating body 16 and the multiple grippers 4A provided thereon constitute a transport mechanism for transporting the container 5. As described above, the neck portion 5A of the container 5 is gripped by the grippers 4A and the flange portion 5B is supported by the grippers 4A, and in this state, the container 5 is transported at a predetermined speed as the rotating body 16 rotates.
The operation of a motor (not shown) that serves as the drive source for the rotating body 16 is controlled by a control device 17. A speed detection mechanism 18 (encoder) that detects the operating speed of the rotating body 16 is attached to the motor that serves as the drive source for the rotating body 16. The conveying speed of the rotating body 16 detected by the speed detection mechanism 18, i.e., the operating speed of the capping device 4, is input to the control device 17.
In this embodiment, when the control device 17 rotates the rotating body 16 using a motor not shown, the operating speed at which the capping head 3 transported by the rotating body 16 attaches caps 8 to a total of 850 containers 5 per minute is defined as the "predetermined operating speed (850 bpm)."
In addition, the control device 17 controls the operation of the motor that drives the rotating body 16, so that, if necessary, the rotating body 16 is rotated at an operating speed (e.g., 750 to 650 bpm) slower than the above-mentioned specified operating speed (850 bpm).
The conveying speed (operating speed) when the rotating body 16 is rotated is detected by a speed detection mechanism 18 and input to the control device 17, and the control device 17 recognizes the operating speed of the capping device 4 based on the detection signal input from the speed detection mechanism 18.

As shown in Figure 2, the capping head 3 comprises a cylindrical outer tube 21 that is mounted on the outer periphery of the rotating body 16 and can be raised and lowered, a spindle 22 that is mounted inside the outer tube 21 and can rotate and rise and fall freely, a chuck 7 attached to the lower end of the spindle 22 and holds the cap 8 in a removable manner, an inner tube 23 that is connected to the upper end of the spindle 22 and has a spline groove formed on its inner periphery, a spline shaft 24 that is spline-fitted into the spline groove of the inner tube 23, and a servo motor 12 connected to the upper end of the spline shaft 24.
The inner cylinder 23, spindle 22 and chuck 7 are capable of ascending and descending relative to the outer cylinder 21, and are supported by a step 21A of the outer cylinder 21. A spring 26 is elastically mounted between the flange 22A on the spindle 22 side and the step 21A inside the outer cylinder 21 that faces it. The spindle 22 and the chuck 7 provided at its lower end are constantly urged downward relative to the outer cylinder 21 by the elastic force of the spring 26.
A cam follower 27 is attached to the inside of the upper part of the outer cylinder 21, and this cam follower 27 is rotatably engaged with a cam groove 28A of an annular cam 28 disposed along the outer periphery of the rotating body 16. The annular cam 28 and the cam follower 27 constitute a lifting mechanism 11 that lifts and lowers the capping head 3.
As the rotating body 16 rotates in the direction of the arrow in Figure 1, the chuck 7 of the capping head 3 is raised and lowered between the upper end and the lower end depending on the height of the cam groove 28A of the lifting mechanism 11 in the required area of the rotation section, and the chuck 7 is rotated in the tightening direction with a predetermined capping torque by the servo motor 12 at a predetermined timing.
3 and 4, at the transfer position A where the container 5 is transferred from the intermediate wheel 6 to the capping device 4 and at the adjacent downstream position thereof, the annular cam 28 of the lifting mechanism 11 is at the top dead center, which is the upper end, and thereafter, the height of the annular cam 28 gradually decreases at the adjacent downstream side in the rotation direction of the rotor 16 before reaching the bottom dead center, which is the lower end B (see FIG. 4). The intermediate region connecting the upper and lower ends of the annular cam 28 is the lowering region C where the capping head 3 is lowered by the annular cam 28. Note that in the adjacent upstream region (not shown) of the transfer position A, the annular cam 28 is configured to return from the lowering end to the upper end.

The operation of the servo motor 12 that rotates the chuck 7 holding the cap 8 is controlled by the control device 17. An encoder 31 that outputs a pulse signal is connected to a rotating portion of the servo motor 12, and an ammeter 32 that detects the output current of the servo motor 12 is also connected to the rotating portion of the servo motor 12. When the servo motor 12 is driven to rotate, the pulse signal output from the encoder 31 is input to the control device 17, and the current output from the servo motor 12 is detected by the ammeter 32 and input to the control device 17.
The control device 17 is adapted to recognize the rotation angle and rotation speed of the servo motor 12 based on the pulse signal detected by the encoder 31. The control device 17 also detects the closing torque acting on the chuck 7 from the current value detected by the ammeter 32 after the servo motor 12 is rotated and records it in chronological order.

Therefore, this embodiment is characterized in that it is configured so that the rotation start timing for rotating the servo motor 12 is changed depending on whether the rotating body 16 of the capping device 4 is operated at a predetermined operating speed (850 bpm) or higher or at an operating speed slower than this predetermined operating speed.
Specifically, when the capping head 3 and the chuck 7 are lowered by the lifting mechanism 11, the control device 17 controls the rotation start timing of the servo motor 12 in the following manner.
When the rotating body 16 is operated at a predetermined operating speed (850 bpm) or higher, the control device 17 recognizes that the rotating body 16 is operating at the predetermined operating speed based on the input signal from the speed detection mechanism 18, and when the chuck 7 (cap 8) is lowered by the annular cam 28 of the lifting mechanism 11 to a time X1 at which the capping head 3 is at the intermediate position of the above-mentioned descent region C, the control device 17 starts rotating the servo motor 12 at that time (see Figures 3 and 4)).
Therefore, from that point X1 until the capping head 3 is lowered to the lower end B by the lifting mechanism 11, the cap 8 is rotated in the tightening direction, so that the lower end 8A' of the screw portion 8A of the rotating cap 8 smoothly contacts the screw portion 5D of the container 5 from above, causing the two screw portions 8A, 5D to mesh with each other.
After the two screw portions 8A, 5A smoothly mesh in this manner, the cap 8 is pressed downward by the spring 26, and then the cap 8 continues to rotate in the tightening direction by the servo motor 12, whereby the screw portion 8A of the cap 8 is tightened onto the screw portion 5D of the container 5, thereby completing the installation of the cap 8.
In other words, in this embodiment, when the rotating body 16 is operated at a predetermined operating speed (850 bpm) or higher, the servo motor 12 is caused to start rotating from a stopped state at the time X1 before the lower end 8A' of the threaded portion 8A of the cap 8 comes into contact with the threaded portion 5D of the container 5.
As a result, the lower end 8A' of the threaded portion 8A of the cap 8 smoothly engages with the threaded portion 5D of the container 5, effectively preventing the above-mentioned "screw step drop" from occurring.
On the other hand, when the rotor 16 is operating at the above-mentioned predetermined operating speed (850 bpm), some trouble may occur in a processing device (not shown) located downstream of the discharge conveyor 14. In that case, the operating speed of the rotor 16 will be operated at an operating speed (e.g., 600 bpm, 750 bpm) slower than the above-mentioned predetermined operating speed. In that case, the speed detection mechanism 18 causes the control device 17 to recognize that the operating speed has become slower than the predetermined operating speed.
Then, the control device 17 keeps the servo motor 12 stopped and does not rotate until the capping head 3 is lowered to the lower end B by the annular cam 28 of the lifting mechanism 11, and starts rotating the servo motor 12 at the time X2 when the capping head 3 is lowered to the lower end B by the lifting mechanism 11. In other words, at the time X2 when the cap 8 is lowered to the lower end B and the lower end 8A' of the threaded portion 8A of the cap 8 comes into contact with the threaded portion 5D of the container 5, the control device 17 starts rotating the servo motor 12 to rotate the cap 8 in the seaming direction and attach it to the mouth 5C of the container 5 (see Figures 3 and 4).

As described above, in this embodiment, when the rotating body 16 of the capping device 4 is operated at a predetermined operating speed (850 bpm), the servo motor 12 is caused to start rotating at the time point X1 when the capping head 3 is located in the middle of the descending region C when it is descended by the lifting mechanism 11. As a result, when the chuck 7 is descended to the descending end B, the cap 8 is also rotating in the tightening direction via the chuck 7, so that the impact when the lower end 8A' of the threaded portion 8A of the cap 8 contacts the threaded portion 5D of the container 5 from above is mitigated, and the two threaded portions 8A and 5D smoothly engage with each other.
This effectively prevents "screw drop" from occurring when the cap 8 is attached to the container 5. This prevents the filling liquid 9 in the container 5 from splashing and adhering to the inner surface of the cap 8 and the threaded portions 8A and 5D due to the impact caused by "screw drop", thereby preventing these locations from being contaminated.
In addition, when the rotating body 16 is operating at a predetermined operating speed (850 bpm), if the operating speed of the rotating body 16 is switched to an operating speed (650 bpm or 750 bpm) slower than the predetermined operating speed, the timing at which the servo motor 12 starts rotating can be changed by the control device 17 in accordance with the operating speed.
Therefore, even if a problem occurs in the downstream processing device and the rotating body 16 is switched from a predetermined operating speed to a slower operating speed, the rotation start timing of the servo motor 12 can be controlled at an appropriate timing accordingly.
5 shows the results of an experiment comparing the state of contamination of the cap 8 after the completion of attachment of the cap 8 when a conventional capping device is used and when the capping device 4 of this embodiment (the present invention) is used. Note that in this experiment, the container 5 is not transported, but the experimental results after the completion of attachment of the cap 8 by the conventional technology and this embodiment are compared in a state where the container 5 is stopped.
As can be seen from the data in Figure 5, in a conventional capping device in which the cap 8 is lowered to the end of its downward movement so that the lower end of the threaded portion of the cap 8 comes into contact with the threaded portion of the container 8 and then the cap 8 is rotated, the maximum amount of filling liquid (product liquid) adhering to the cap 8, etc. is 51 mg.
In contrast, in the case of this embodiment in which the cap 8 is rotated and attached to the container 5 midway down in the descending region C, the amount of the filling liquid (product liquid) adhering is 1 mg. As is clear from the experimental results shown in Fig. 5, it can be presumed that the capping device 4 of this embodiment can suppress the "screw dropout" phenomenon compared to the conventional one, and can effectively suppress contamination of the cap 8, etc., due to liquid splashing caused by the impact when the screw dropout occurs.
In the above embodiment, the predetermined operating speed is 850 bpm, but the predetermined operating speed is not limited to 850 bpm and may be 900 bpm or more and 1000 bpm or more. Even in this case, the cap 8 is rotated and attached to the container 5 during the descent in the descent region C.

Description of the Reference Numerals 3: Capping head 4: Capping device 5: Container 5C: Mouth portion 5D: Screw portion 7: Chuck 8: Cap 8A: Screw portion 8A': Lower end portion of screw portion 9: Filling liquid 11: Lifting mechanism 12: Servo motor 16: Control device 18: Speed detection mechanism

Claims (1)

a capping head having a chuck for holding a cap and attaching a cap to an opening of the container transported by the transport mechanism; a servo motor for rotating the chuck of the capping head; a lifting mechanism for raising and lowering the capping head; and a control device for controlling the operation of the servo motor and the transport mechanism;
a capping head holding a cap by the chuck is lowered by the lifting mechanism, and the servo motor starts to rotate the chuck from a stopped state, thereby rotating the cap held by the chuck and wrapping and attaching it to the mouth of a container,
a speed detection mechanism for detecting a speed at which the container is conveyed by the conveying mechanism, and the speed at which the container is conveyed by the conveying mechanism detected by the speed detection mechanism is input to the control device ;
The control device includes:
When the container conveying speed by the conveying mechanism is switched between a high predetermined operating speed and an operating speed slower than the high predetermined operating speed, the rotation start timing of the servo motor is automatically switched in accordance with the conveying speed of the conveying mechanism,
When the conveying mechanism conveys the container at the predetermined operating speed, the rotation of the servo motor is started in a direction for fastening the cap while the chuck of the capping head is being lowered by the lifting mechanism and before the threaded portion of the cap held by the chuck comes into contact with the threaded portion of the container,
A capping device characterized in that, when the conveying mechanism conveys a container at an operating speed slower than the specified operating speed, the chuck of the capping head is lowered by the lifting mechanism, and the screw portion of the cap held by the chuck comes into contact with the screw portion of the container, and then the servo motor starts to rotate in the direction of tightening the cap .

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