JPH0786034B2 - Capping method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capping method for screwing a cap onto a container.

[0002]

2. Description of the Related Art Generally, when a cap is screwed onto a container, it is first screwed onto the container with a light tightening force until the rotation of the cap is stopped. I try to tighten the cap on the container. As a conventional capper that executes such an idea, a capping head is rotatably driven with a predetermined command torque by a torque motor whose output torque is controllable, and a cap held by the capping head is screwed into a container with a predetermined capping torque. It is known that the person wears it (Japanese Patent Laid-Open No. 59-59160).
-62,488 JP, JP-A-60-110689 Patent Publication No.
News ).

[0003]

However, the conventional capper has a drawback that abnormal screwing, which is called a beret cap, tends to occur when the cap is inclined, especially when screwing of the cap is started. . Further, in the capper, when the command torque is matched with a predetermined capping torque for screwing the cap to the container, the capping torque of the cap is set to the capping torque at the moment when the cap is fastened to the container and the rotation of the capping head is stopped. Since the inertia torque of the capping head is applied, the actual capping torque becomes larger than the predetermined capping torque by the inertia torque. So to solve such problems,
The command torque may be set smaller by the amount of inertia torque, but friction in the process of tightening the cap on the container due to external conditions such as fluctuations in atmospheric temperature and humidity, particularly whether the cap or container is dry or wet. Due to the fluctuation of the force, the deceleration of the capping head and thus the inertia torque greatly fluctuate, and it is difficult to control the capping torque with high accuracy so that the capping torque is always constant.
Further, even if it was possible to tighten with a constant capping torque, it was not possible to obtain a constant capping torque due to the change in the friction coefficient due to the wet state of the packing in the container or the cap. In view of the above circumstances, the present invention as well as to be able to prevent the occurrence of beret cap as much as possible during screwing the start of the cap, as much as possible even wet condition of the container and the cap is varied in _Jo A capping method capable of obtaining a cap opening torque.

[0004]

That is, the present invention provides a capping method in which a cap held on a capping head is rotated in a tightening direction to tighten the cap on a container, and the cap held by the capping head is attached to the container. after fitted into the mouth portion, reversely rotates the capping head at least to a position where the capping head engagement with the edge of the tip portions of both the screw portion is dropped between the cap and the container Rutotomoni, position in which the cap is dropped Is detected as the tightening start position, and the capping head is rotated from that position in the tightening direction by a predetermined rotation angle, and the tightening of the cap to the container is completed.

[0005]

In the capping method of the present invention, the cap held by the capping head is fitted into the mouth of the container and then the cap is not immediately rotated in the tightening direction, but at least both screws of the cap and the container are screwed. The capping head is reversely rotated to a position where the tip end of the part disengages and the capping head falls. When the capping head is dropped, the depth of fitting between the cap and the mouth of the container becomes deeper, and the impact of the drop causes the cap to move as far as possible, compared with the case where the cap is simply put on the mouth of the container. The container mouth portion can be horizontally covered, and thereby, the engagement between the threaded portion of the container and the threaded portion of the container can be made as appropriate as possible. Therefore, when the capping head is then rotated in the tightening direction to tighten the cap on the container, both screw parts are smoothly screwed together to prevent the occurrence of the beret cap as much as possible. Further, in the present invention, the position where the capping head falls is detected as the tightening start position, and from that position the capping head is rotated in the tightening direction by a predetermined rotation angle to complete the tightening of the cap to the container. Therefore, regardless of the wet state of the cap or container, the amount of tightening of the cap to the container, that is, the top end surface of the mouth of the container is in close contact with the cap itself or the packing inside the cap, compresses it. The amount can be constant. In particular, in recent years, the manufacturing precision of the cap and the container is improved, and substantially the same product can be manufactured between the products, so that it is possible to obtain substantially the same compression amount between the products. There is. Then, the opening torque for loosening the cap is obtained from the compression amount and the frictional force of the threaded portion, and the frictional force changes depending on the wet state of the threaded portion, but the threaded portion is sealed from the inside of the container. In addition, since the container is generally stored in a dry state, even if the screw part is wet during tightening, it will be in a dry state during storage, so the above friction force is usually a constant value in a dry state. Becomes As a result, it is possible to maintain the opening torque constant by maintaining the compression amount constant.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In FIG. 1, a container 1 can be fixed by a container gripping mechanism 2 and is rotatably driven by a torque motor 3 at a position directly above the container gripping mechanism 2. A capping head 4 is provided. This capping head 4
Can be composed of, for example, a conventionally known air chuck that grips the cap 5 using air pressure. The torque motor 3 is moved up and down by an elevator mechanism (not shown), and the capping head 4 is connected to the torque motor 3 via a pair of spline shafts 41a and 41b. A stopper 42 is attached to the upper end of the spline shaft 41b on the capping head 4 side, and the stopper 42 is engaged with a slit 43 provided over a predetermined range of the hollow spline shaft 41a on the torque motor 3 side. As a result, both spline shafts 41
The a and 41b can be expanded and contracted within the range of the slit 43. The torque motor 3 is normally located at the ascending end position, and the capping head 4 is located at the descending end position where the stopper 42 abuts on the lower end of the slit 43. It is designed so that it can be raised and lowered as it goes up and down. Then, even if the torque motor 3 is lowered and the cap 5 held by the capping head 4 is fitted into the mouth portion of the container 1 and thereby the descent of the capping head 4 is stopped, the torque motor 3 is further driven by the spline shafts 41a and 41b. 3 can descend. The torque motor 3 is provided with a rotation detector 6 such as a tacho-generator or a rotary encoder for detecting the number of rotations thereof, and an output torque detector for detecting the actual output torque of the torque motor 3 and thus the capping head 4. 7 is provided so that the detection signals from the detectors 6 and 7 are respectively input to the control device 8 such as a microcomputer.

The control device 8 is adapted to rotate the torque motor 3 with a command torque of a predetermined magnitude to screw the cap 5 held by the capping head 4 into the container 1. As a specific example of the command torque, the current supplied to the torque motor 3 can be used. The torque motor 3 depends on the magnitude of the current.
When controlling the output of the torque motor 3, an ammeter for detecting the current value actually supplied to the torque motor 3 may be used as the output torque detector 7 for detecting the actual output torque of the torque motor 3. it can. The output torque detector 7 may directly detect the output torque of the capping head 4, and the voltage supplied to the torque motor 3 can be used as another example of the command torque. Further, a position detector 9 is provided on the spline shaft 41a on the torque motor 3 side to detect the vertical position of the stopper 42, that is, the vertical position of the spline shaft 41b on the capping head 4 side with respect to the spline shaft 41a on the torque motor 3 side. Yes, the signal from the position detector 9 is input to the control device 8 via a rotary joint (not shown).

In the above structure, the container 1 is supplied to the container gripping mechanism 2 and gripped, and the cap 5 is supplied to the capping head 4 in the rotation stopped state and gripped.
When the container gripping mechanism 2 grips the container 1, the control device 8
Lowers the torque motor 3 and the capping head 4 to fit the cap 5 into the mouth of the container 1. At this time, as described above, the torque motor 3 is lowered and the cap 5 held by the capping head 4 is fitted into the mouth portion of the container 1, and even if the lowering of the capping head 4 is stopped by this, the predetermined value of the torque motor 3 is obtained. The descent to the position continues. Therefore, the spline shaft 41b on the capping head 4 side is the spline shaft 41 on the torque motor 3 side.
It comes to rise with respect to a. Next, as shown in FIG. 2, the control device 8 activates the torque motor 3 in the reverse rotation direction with a relatively small command torque 10 to move the capping head 4 from its stop position A to the cap 5 in the container 1.
Rotate in the direction opposite to the forward direction that is tightened in. The speed of the capping head 4 at this time is shown by reference numeral 20, and the output torque of the capping head 4 is shown by reference numeral 30.

When the capping head 4 is rotated in the reverse direction, the capping head 4 is gradually rotated by the reverse rotation along the inclination of the screw portion of the cap 5 and the container 1, and eventually both the cap 5 and the container 1 are rotated. When the engagement of the tip portion of the screw portion is disengaged, the capping head 4 suddenly drops. During this time, the control device 8 monitors the ascending / descending position of the spline shaft 41b on the capping head 4 side with respect to the spline shaft 41a on the torque motor 3 side by a signal from the position detector 9, and the screws of the cap 5 and the container 1 are both monitored. When the capping head 4 is suddenly dropped due to the disengagement of the tip end of the portion, the position is stored as the tightening start position B. Then, the control device 8 further reverses the capping head 4 from the tightening start position B by, for example, 0.2 rotation, and then stops the rotation. In addition,
The capping head 4 may be stopped immediately at the tightening start position B. In this state, the cap 5 and the container 1
The depth of fitting with the mouth portion of the container is deep, and the impact of dropping the capping head also acts, so that the engagement between the threaded portion of the cap 5 and the threaded portion of the container 1 is as appropriate as possible. Has become. Therefore, when the capping head 4 is subsequently rotated in the tightening direction to tighten the cap 5 on the container 1, both screw parts are smoothly screwed together to prevent the occurrence of a beret cap as much as possible. You can

When the control device 8 stops the reverse rotation of the capping head 4, the control device 8 then moves to the torque motor 3 next.
Is rotated forward with a relatively large command torque 11. The magnitude of the command torque 11 at this time is set relatively large, and as described above, the capping head 4
When the beret cap is generated despite the occurrence of the beret cap by reversing the above, the cap 5 can be forcibly screwed into the container 1 by the relatively large command torque 11 described above. I am able to do it. The value of the command torque 11 at this time is set in consideration of the material and shape of the cap 5, and is continued until the cap 5 makes at least one rotation. Next, when the cap 5 makes one rotation, the cap 5 is screwed into the mouth portion of the container 1, so that the control device 8 causes the torque motor 3 to have a command torque smaller than the command torque 11 at the start of capping. 12
Drive with. Until the cap 5 is rotated as required,
Since the capping head 4 is rotated substantially in the state of idling, the capping head 4 is rotated at the maximum speed 22, and the output torque 31 of the capping head 4 during this period is maintained substantially zero.

The control device 8 constantly monitors the rotation angle of the capping head 4 based on the signal from the rotation detector 6, and when the capping head 4 rotates from the tightening start position B by a predetermined rotation angle θ. Then, the rotation is stopped and the tightening of the cap 5 to the container 1 is completed. During this time, before the capping head 4 rotates from the tightening start position B by a predetermined rotation angle θ,
The mouth of the container 1 comes into close contact with a packing (not shown) in the cap 5 and compresses it, whereby the capping head 4
And the output torque 32 increases. In this embodiment, since the command torque 12 is set small, the rotation of the capping head 4 is stopped by the resistance force from the container side before the capping head 4 is rotated by the predetermined rotation angle θ. Therefore, even if the rotation of the capping head 4 rapidly stops from the high speed rotation and a large moment of inertia is added to the tightening force of the cap, the tightening torque does not unnecessarily increase. When the rotation of the capping head 4 is stopped by the small command torque 12, the control device 8 gradually increases the command torque 13, whereby the capping head 4 starts to rotate again and its rotation speed 24 is increased. If the resistance force from the container increases more than the increase of the command torque 13 due to the increase of the rotation, the rotation speed 25 again decreases. At this time, as described above, the control device 8 constantly monitors the rotation angle of the capping head 4 based on the signal from the rotation detector 6, and the capping head 4 moves from the tightening start position B by a predetermined rotation angle θ. When the capping head 4 is rotated, a rotation stop signal for the capping head 4 is output, and specifically, the command torque is set to zero to stop the rotation of the capping head 4.
This completes the fastening of the cap 5 to the container 1.

In this way, the cap 5 is rotated in the reverse direction, and the position at which the tips of the screw parts of the cap 5 and the container 1 are disengaged is detected as the tightening start position B, and the tightening start position B is detected. Since the capping head 4 is rotated by a predetermined rotation angle θ to complete the tightening of the cap 5, the upper end surface of the mouth of the container 1 compresses the packing of the cap 5 regardless of the wet state of the container 1 or the cap 5. The amount of compression applied can be made constant, and as a result, the opening torque of the cap 5 can be made constant in a general dry state, as described above. In the above embodiment, if the rotation speed of the capping head 4 is high when the rotation stop signal is output, the rotation proceeds until the capping head 4 actually stops. It goes without saying that the rotation stop signal of the capping head 4 can be output earlier by taking into consideration the magnitude of the rotation speed of the capping head 4 when outputting the rotation stop signal. Further, in the above embodiment, the rotation speed 2 of the capping head 4 is once.
Although 3 is set to zero, the temporary tightening is performed, and then the final tightening is performed in two steps, but the main tightening may be performed or the control may be performed in three or more steps. .

[0013]

As evident from the foregoing description, according to the present invention, Rutotomoni effect is obtained that it is possible to prevent the occurrence of beret cap as much as possible, containers and container mouth regardless of a wet state of the cap Since the upper end surface of the part can keep the amount of compression of the cap itself or its packing constant,
The effect that the cap opening torque in a general dry state can be made constant can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory view for explaining the operation of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Container 2 ... Container holding mechanism 3 ... Torque motor 4 ... Capping head 5 ... Cap 6 ... Rotation detector 8 ... Control device 7 ... Output torque detector 9 ... Position detector 10-13 ... Command torque 20, 22-25 ... Rotation speed 30 to 32 ... Output torque A ... Stop position B ... Tightening start position θ ... Rotation angle

Claims (1)

[Claims] 1. A capping method in which a cap held by a capping head is rotated in a tightening direction to tighten the cap on a container, after the cap gripped by the capping head is fitted to the mouth of the container, When at least the cap and capping head engagement with the edge of the tip portions of the threaded portion of the container is Ru reversely rotates the capping head to a position falling
In both cases, the position where the cap has dropped is the tightening start position.
The capping head is detected from that position.
Rotate in the tightening direction by the specified rotation angle to
A capping method characterized by terminating tightening of a cap to a container .