JPH0563399B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a capping method for screwing a cap onto a container.

``Prior art'' Generally, when screwing a cap onto a container, the cap is first screwed onto the container with a light tightening force until the cap stops rotating, and then, once that state is reached, the required tightening force is applied. The cap is tightened onto the container.

A conventional capper that implements this idea uses a torque motor whose output torque can be controlled to rotate a capping head with a predetermined command torque, and then rotates the cap gripped by the capping head to a predetermined position. It is known that the cap is screwed onto the container using a closing torque (Japanese Patent Application Laid-Open No. 1983-1999).
No. 62488, Japanese Patent Publication No. 60-110689).

``Problems to be Solved by the Invention'' However, in the above cap, when the command torque is made to match the predetermined closing torque for screwing the cap onto the container, the cap is tightened to the container and the capping head is tightened. At the moment the rotation stops, the inertia torque of the capping head is added to the closure torque of the cap, so the actual closure torque becomes larger than the predetermined closure torque by the amount of inertia torque.

Therefore, in order to solve this problem, the above command torque can be set smaller by the inertia torque. Due to various conditions, the deceleration of the capping head and the inertia torque described above vary greatly due to fluctuations in frictional force during the process of tightening the cap to the container. It was difficult to control with high precision.

Furthermore, even if it were possible to tighten the cap with a constant closing torque, it was not possible to obtain a constant opening torque due to changes in the coefficient of friction due to the wet state of the packing inside the container or cap.

``Means for Solving the Problems'' In view of such circumstances, the present invention is designed to perform capping by rotating the cap by a predetermined rotation angle, instead of tightening the cap to a standard closing torque and completing the capping work. This is to finish the work.

That is, the capping method of the present invention rotates the cap held in the capping head with a relatively small rotational torque with respect to the container, detects that both have reached a predetermined tightening start position, and then rotates the cap held by the capping head with a relatively small rotational torque. When the rotation of the cap is substantially stopped by the resistance force from the container side against the torque, the rotational torque is increased to continue the rotation of the cap relative to the container, and the capping head is moved from the tightening starting position. The cap is rotated by a predetermined rotation angle to finish tightening the cap onto the container.

"Operation" In the capping method described above, the cap held in the capping head is initially rotated with a relatively small rotational torque with respect to the container, so the resistance force from the container side against the small rotational torque is used. Thus, the rotation of the cap can be substantially stopped, thereby eliminating the large inertial forces caused by the previous high speed rotation of the capping head.

When the rotation of the cap is substantially stopped, the rotational torque is increased to continue the rotation of the cap relative to the container,
Since the rotation of the capping head after this does not become so large, the above-mentioned inertial force can be kept small, and the adverse effects of the inertial force can be reduced.

In addition to this, it is detected that the cap and the container are at a predetermined tightening start position, and the capping head is rotated by a predetermined rotation angle from the tightening start position to tighten the cap onto the container. This means that regardless of the wet state of the cap or container, the amount of tightening of the cap to the container is determined by the amount of tightening of the cap to the container, that is, the amount of tightening of the cap to the container, i.e., the amount by which the upper end of the mouth of the container comes into close contact with the cap itself or the packing inside the cap, compressing it. The amount of compression can be kept constant. Particularly in recent years, the manufacturing precision of caps and containers has improved, making it possible to manufacture substantially the same product for each product, making it possible to obtain virtually the same amount of compression for each product. There is.

The opening torque when loosening the cap is obtained from the above compression amount and the frictional force of the threaded part, and the frictional force changes depending on the wetness of the threaded part, but the threaded part is sealed from inside the container. Being there,
And containers are generally stored in a dry state, so even if the threaded part is wet when tightened, it becomes dry during storage, and therefore the above frictional force is usually a roughly constant value in a dry state. Become. As a result, by maintaining the compression amount constant, it becomes possible to control the opening torque at a constant level.

"Example" The present invention will be described below with reference to the illustrated example.
In FIG. 1, a container 1 can be fixed by a container gripping mechanism 2, and a capping head 4 rotatably driven by a torque motor 3 is provided directly above the container gripping mechanism 2. . This capping head 4 can be constructed, for example, from a conventionally known pneumatic jack that grips the cap 5 using air pressure.

The torque motor 3 is raised and lowered by a lifting mechanism (not shown), and the capping head 4 is connected to the torque motor 3 via, for example, a spline shaft.

The torque motor 3 is normally located at the upper end position, and the capping head 4 is located at the lower end position, and the capping head 4 is raised and lowered in this state as the torque motor 3 moves up and down. It's becoming like that. Then, the torque motor 3 is lowered and the cap 5 held by the capping head 4 is fitted into the opening of the container 1, and even if the lowering of the capping head 4 is thereby stopped, the torque motor 3 is further lowered. It is now possible to descend.

The torque motor 3 is provided with a rotation detector 6 such as a tachometer generator or rotary encoder for detecting its rotation speed, and an output for detecting the actual output torque of the torque motor 3 and therefore of the capping head 4. Torque detector 7
are provided, and the detection signals from the respective detectors 6 and 7 are respectively input to a control device 8 such as a microcomputer.

The control device 8 is configured to rotate the torque motor 3 with a command torque of a predetermined magnitude so that the cap 5 held by the capping head 4 can be screwed onto the container 1. A current supplied to the torque motor 3 can be used as a specific example of the command torque.

When the output of the torque motor 3 is controlled by the magnitude of the current, the output torque detector 7 detects the actual output torque of the torque motor 3, and the output torque detector 7 detects the current actually supplied to the torque motor 3. An ammeter can be used to detect the value. 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 may be used as another example of the command torque. .

In the above configuration, the container 1 has a container gripping mechanism 2
The cap 5 is supplied to and gripped by the capping head 4 which is in a non-rotating state. 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 opening of the container 1, and then adjusts the torque motor 3 to a predetermined size as shown in FIG. command torque 11
Start it with .

The magnitude of the command torque 11 at this time is set relatively large, and when starting to screw the cap 5 into the container, it is necessary to avoid abnormal screwing when the cap 5 is tilted, which is called a beret cap. Even if
The cap 5 can be forcibly screwed into the container 1 by a relatively large command torque 11. The value of the command torque 11 at this time is set in consideration of the material, shape, etc. of the cap 5.
This continues until the cap 5 rotates at least once.

Next, when the cap 5 rotates once, the cap 5 will be screwed into the mouth of the container 1.
The control device 8 drives the torque motor 3 with a command torque 12 smaller than the command torque 11 at the start of capping. Until the cap 5 is rotated as required, the capping head 4 is rotated in a substantially idle state, so that the capping head 4 is rotated at a maximum speed of 22, and during this time the capping head 4 is rotated at a maximum speed of 22. The output torque 31 of is maintained at approximately zero.

When the cap 5 is rotated a predetermined amount and the upper end surface of the mouth of the container 1 comes into close contact with a packing (not shown) inside the cap 5 and compresses it, the rotational speed 23 of the capping head 4 decreases and the output torque 32 will increase.

The control device 8 detects that the actual tightening of the cap 5 has started when the output torque 32 of the capping head 4 has exceeded a predetermined value 32a, that is, the cap 5 and the container 1 have started to be tightened. When it is detected that the capping head 4 has reached the predetermined tightening start position 32a, the rotation angle of the capping head 4 is monitored based on the signal from the rotation detector 6, and the capping head 4 is rotated from the tightening start position 32a in advance. After rotating by a predetermined rotation angle, the rotation is stopped and the tightening of the cap 5 to the container 1 is completed.

In this embodiment, by setting the command torque 12 to a small value, the capping head 4 is stopped by a resistance force from the container side before it rotates by a predetermined rotation angle θ from the tightening start position 32a. As a result, even if the rotation of the capping head 4 suddenly stops from high speed rotation and a large moment of inertia is added to the cap tightening force, the tightening torque will not become unnecessarily large. I try not to.

When the capping head 4 stops rotating, the control device 8 gradually increases the command torque 13, so that the capping head 4 starts rotating again and its rotational speed 24 increases. The command torque 13 increases due to its rotation.
When the resistance force from the container increases beyond the increase in , the rotational speed 25 begins to decrease again.

During this time, the control device 8 monitors the rotation angle of the capping head 4 as described above, and when the capping head 4 rotates by a predetermined rotation angle θ from the tightening start position 32a, the capping head 4 is rotated by a predetermined rotation angle θ. A signal to stop the rotation of the capping head 4 is output, specifically, the command torque is set to zero to stop the rotation of the capping head 4, thereby completing the tightening of the cap 5 to the container 1.

In this way, the upper end surface of the mouth of the container 1 is connected to the cap 5.
After detecting the tightening start position 32a at which the capping head 4 comes into close contact with and compresses the packing (not shown) inside, the capping head 4 is rotated at a predetermined rotation angle θ.
Since the tightening of the cap 5 is completed by rotating the cap 5 by a certain amount, the amount of compression by which the upper end surface of the opening of the container 1 compresses the gasket of the cap 5 can be kept constant regardless of the wet state of the container 1 or the cap 5. As a result, as described above, the opening torque of the cap 5 can be kept constant in a general dry state.

In the above embodiment, the tightening start position 32a is detected from the output torque of the capping head 4, but the invention is not limited to this. Later, the rotational speed of the capping head 4 may be detected, and the position where the capping head 4 has fallen by a predetermined value from the maximum speed 22 may be set as the tightening start position. It is also possible to position the container 1 and the cap 5 at a predetermined rotation angle position and use that position as the tightening start position.

Furthermore, in the above embodiment, if the rotation speed of the capping head 4 is high when the rotation stop signal is output, the rotation of the capping head 4 will continue until it actually stops. It goes without saying that the control device 8 allows the rotation stop signal of the capping head 4 to be output early, taking into account the magnitude of the rotation speed of the capping head 4 when outputting the rotation stop signal. be. Furthermore, in the above embodiment, the rotational speed 23 of the capping head 4 is set to zero to perform temporary tightening, and then final tightening is performed, so that the control is divided into two stages. It may be controlled separately.

"Effects of the Invention" As described above, according to the present invention, the amount of compression of the cap itself or its packing by the upper end surface of the mouth of the container can be made constant regardless of the wet state of the container or the cap. In general, the effect that the opening torque of the cap in a dry state can be made constant can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention;
FIG. 2 is an explanatory diagram for explaining the operation of FIG. 1. DESCRIPTION OF SYMBOLS 1... Container, 2... Container gripping mechanism, 3... Torque motor, 4... Capping head, 5... Cap, 6... Rotation detector, 8... Control device, 7
...Output torque detector, 11-13... Command torque, 22-25... Rotation speed, 31, 32... Output torque, 32a... Tightening start position, θ... Rotation angle.

Claims (1)

[Claims] 1 Rotate the cap held in the capping head with a relatively small rotational torque with respect to the container, detect when both have reached a predetermined tightening start position, and reduce the resistance from the container side to the small rotational torque. once the rotation of the cap is substantially stopped by the force, increasing the rotational torque to continue rotation of the cap relative to the container;
The capping method further comprises: rotating the capping head by a predetermined rotation angle from the tightening start position to finish tightening the cap onto the container.