JP2001072186A - Capping method and capping apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately judge a seating point regardless of solid difference between a cap and a container or whether the container is wet or dry. SOLUTION: A rotary encoder 6 is attached to a torque motor 3 to input one pulse to a control device 8 at each time when the torque motor 3 is rotated. The output torque at a time when the torque motor 3 is rotated is detected by a torque detector 7 to be inputted to the control device 8. When a control part 8A drives the torque motor 3, an operation part 8B calculates the change quantity of the output torque per a unit angle of rotation and a comparing part 8C compares this change quantity with a predetermined reference value. At a point of time when the change quantity exceeds the reference value, the control device 8 judges that the upper end of the mouth part 1a of the container becomes the seating point brought into contact with the packing 9 in a cap 5 and seams the cap 5 by a predetermined angle of rotation from this point of time to stop the operation of the torque motor 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, there is known a capping method in which a capping head for detachably holding a cap and a motor for rotating the capping head are provided, and the cap held by the capping head is screwed to a container. (Eg, Japanese Patent Laid-Open No. 5-63399). In the above-mentioned conventional method, when the cap held by rotating the capping head is screwed into the container, first, the lower end of the cap-side screw is fitted into the screw at the upper end of the container, and then, Further, the upper end of the mouth of the container and the packing (sealant) provided on the top surface in the cap come into contact with each other. The point at which the upper end opening of the container comes into contact with the packing on the top surface inside the cap is conventionally generally referred to as a seating point. Then, in the above-described conventional method, paying attention to the fact that the output torque sharply increases at the seating point, it is determined that the output torque has reached the seating point when the output torque exceeds a predetermined threshold, From that point, the cap is wound (rotated) by a predetermined rotation angle to terminate the capping.

[0003]

However, the above-mentioned conventional method has the following disadvantages. That is, the screw resistance of the cap and the container screwed to the container is
Screw the cap to the container because the frictional force of the screw surface differs depending on the solidity difference due to the accuracy error of the material and screw shape, and the degree of drying of the washed container, that is, when the container is dry and wet For this purpose, the required closing torque also differs depending on individual differences and whether the container is dry or wet at the time of capping. By the way, in the above-mentioned conventional capping method, the above-mentioned threshold value is set to a constant value without taking the above-mentioned points into consideration, so that the seating point cannot be accurately grasped. That is, as shown in FIG. 7, when the container is wet, the frictional force is smaller than when the container is dry, so that the threshold value is delayed, so that it is a seating point. The timing to grasp is delayed.
Therefore, when the cap is rotated by a predetermined angle from the point in time when the threshold value is exceeded, the tightening angle becomes larger than when the container is dry. As a result, variations in the tightened state of the cap have occurred. Therefore, the present invention accurately grasps the seating point regardless of the difference between the cap and the container and whether the container is dry or wet at the time of capping, and ends the capping by winding the cap from the seating point by a predetermined rotation angle. It is configured so that

[0004]

That is, a capping head having a capping head for detachably holding a cap and a motor for rotating the capping head, wherein the cap held by the capping head is screwed to a container. In the method, an amount of change in output torque per unit rotation angle when the motor is rotated is determined, and the amount of change is compared with a predetermined reference value. By rotating the cap by a predetermined rotation angle, screwing the cap onto the container is completed. According to a second aspect of the present invention, there is provided a capping head for detachably holding a cap, a motor for rotating the capping head, and a control device for controlling the rotation of the motor, wherein the cap held by the capping head is contained in a container. In the capping device that is screwed, a rotation detector that outputs a pulse signal for each unit rotation angle of the motor, and a torque detection unit that detects an output torque of the motor are provided. A control unit that controls the operation, based on the pulse signal output by the rotation detector and the output torque value output by the torque detection unit, determines the amount of change in output torque per unit rotation angle when the motor is rotated. A calculating unit for determining the amount of change obtained by the calculating means, and a comparing unit for comparing the amount of change obtained by the calculating means with a predetermined reference value When the amount of change obtained by the calculation unit exceeds a predetermined reference value, the control unit rotates the motor by the number of pulses corresponding to the predetermined rotation angle from the pulse signal at the time when the change amount exceeds the predetermined reference value, and The screwing to the container is terminated.

[0005]

According to such a method and apparatus, the seating point can be accurately grasped without being affected by the individual difference of the cap and the container, and whether the container is wet or dry at the time of capping. Therefore, regardless of such factors, the cap can be accurately rotated from the seating point by a predetermined rotation angle and screwed onto the container.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiment. Referring to FIG.
A capping head 4 rotated by a torque motor 3 is provided immediately above the container gripping mechanism 2. The capping head 4 can be composed of a conventionally known air chuck that detachably holds the cap 5 using, for example, 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 a rising end position, and the capping head 4 is located at a falling end position. The capping head 4 is moved up and down as the torque motor 3 moves up and down in that state. ing. Then, the torque motor 3 is lowered and the cap 5 gripped by the capping head 4 is moved to the mouth 1 a of the container 1.
(See FIG. 2) so that the torque motor 3 can be further lowered even when the lowering of the capping head 4 is stopped. The torque motor 3 has a rotary encoder 6 for detecting its rotation angle.
And a torque detector 7 for detecting the actual output torque of the torque motor 3 and therefore of the capping head 4 is provided. The detection signals from the rotary encoder 6 and the torque detector 7 are respectively transmitted to a microcomputer or the like. The data is input to the control device 8.

The control unit 8 includes a control unit 8A for controlling the operation of the torque motor 3, and the control unit 8A drives the torque motor 3 to rotate at a required magnitude of the command torque to thereby control the operation of the capping head 4A. Cap 5 gripped on
Can be screwed onto the container 1.
As a specific example of the command torque, a current supplied to the torque motor 3 can be used. The torque detector 7 may directly detect the output torque or may detect the output torque from the supplied current value. Here, the operation of the capping device based on the above-described configuration will be briefly described. The container 1 is supplied to the container gripping mechanism 2 and is gripped, and the cap 5 is supplied to the capping head 4 in a rotation stopped state and gripped. You. When the container gripping mechanism 2 grips the container 1, the torque motor 3 and the capping head 4 are lowered by an elevating mechanism (not shown) so that the cap 5 is fitted to the upper end of the opening 1 a of the container 1 (see FIG. 2). The control unit 8A of the control device 8 drives the torque motor 3 with a command torque of a predetermined magnitude.

Next, while the cap 5 rotates, the cap 5 is screwed onto the upper end of the mouth 1a of the container 1, and thereafter, the output torque of the capping head 4 becomes
It is maintained at a value commensurate with the screw resistance of the cap 5 and the container 1 at that time. As shown in FIG. 3, the upper end of the mouth 1a of the container 1 is brought into contact with a packing 9 as a seal provided on the top surface of the cap 5 to compress the cap 5 by rotating the cap 5 a predetermined time (see FIG. 3). At the seating point, the rotational speed of the capping head 4 decreases and the output torque increases (see FIG. 4). As will be described in detail later, in the present embodiment, focusing on this, the control device 8 determines that the seating point has been reached, and rotates the torque motor 3 by a predetermined rotation angle from the seating point to thereby perform capping. The head 4 (cap 5) is wound (rotated) to terminate the screwing of the cap 5 onto the container 1. When the cap 5 is attached to the container 1 in this manner, the capping head 4 releases the gripping state of the cap 5, and then the capping head 4 is lifted and separated from the container 1.
Thus, the control device 8 of the present embodiment includes the calculation unit 8B that calculates the change rate R of the output torque, and compares the change rate R obtained by the calculation unit 8B with a previously stored reference value X. 8C. And the control device 8
As described above, by performing the following processing, it is possible to accurately grasp that the cap 5 has become the seating point regardless of the difference between the cap and the container and whether the cap 5 is wet or dry at the time of capping. The capping head 4 (cap 5) is rotated from the seating point by a predetermined rotation angle. Note that the fluctuation of the output torque also occurs in a state in which the cap 5 called a beret cap is inclined. Therefore, the control device 8 of the present embodiment takes the above-described seating point into consideration in consideration of the case where a beret cap occurs. I try to judge that it has become.

That is, as shown in FIG.
Drive unit 8A drives the torque motor 3 (S
1) A pulse is input from the rotary encoder 6 to the control device 8 for each unit rotation angle dθ. More specifically,
The rotary encoder 6 inputs one pulse to the control device 8 each time the torque motor 3 is rotated once, so that 360 rotations per one rotation of the torque motor 3.
A pulse is input to the control device 8. The output torque is detected by the torque detector 7 each time this pulse is input to the control device 8, and is sequentially input to the control device 8. Here, the control device 8 stores the value one pulse before as the output torque input from the torque detector 7. When the torque motor 3 is driven, the calculation unit 8B of the control device 8 calculates the change rate R of the output torque, and the comparison unit 8C of the control device 8 calculates the change rate R obtained by the calculation unit 8B.
Is compared with a reference value X stored in advance (S2). Note that the output torque change rate R is obtained by dividing the difference dT between the previous output torque and the current output torque input to the control device 8 by the unit rotation angle dθ of the rotary encoder 6. As shown in FIG. 5, before the seating point, the rate of change R is less than the reference value X. In this case, the rate of change R and the reference value X
Is compared. On the other hand, as shown in FIG. 5, when the seating point is reached, the rate of change R exceeds the reference value X. In this case, the control device 8 determines that the upper end of the mouth 1a of the container 1 9 is determined to be the seating point (FIG. 3) that has come into contact. Once the seating point is reached,
Although the rate of change R exceeds the reference value X, in this case, the rate of change R is ignored. In FIG. 5, the broken line indicates the actual measured value, and the solid line indicates the average of the actual measured values.

Here, as shown in FIG. 4, when the relationship between the output torque and the rotation angle of the cap 5 is examined, the fluctuation of the output torque becomes large when comparing before and after reaching the seating point. That is, as shown in FIG. 5, the change rate R, that is, dT / dθ, fluctuates rapidly before and after the sitting point.
Based on this, the control device 8 determines that the seating point has been reached. Thereafter, the control unit 8A of the control device 8 drives the torque motor 3 by this time, and then checks whether the cap 5 is rotated by a predetermined rotation angle (S3). Here, if the cap 5 has not been rotated by the predetermined rotation angle since the driving of the torque motor 3, the operation returns to the previous position and again the calculation unit 8 of the control device 8.
B calculates the rate of change R, and the comparing unit 8C compares the rate of change R with the reference value X. On the other hand, when the cap 5 has already been rotated by the predetermined rotation angle after driving the torque motor 3, the control device 8 determines that the time when the rate of change R exceeds the reference value X was the seating point. Judgment is made, and the pulse counting is started by the built-in counter with the pulse at that time set to 1 (S4). When the torque motor 3 rotates from this point until the counter counts, for example, 70 pulses, that is, the cap is rotated 70 degrees as a predetermined rotation angle (S5), and the control device 8
Of the control unit 8A stops the operation of the torque motor 3. As described above, in the present embodiment, the control device 8 determines that the time when the rate of change R of the output torque per unit rotation angle dθ exceeds the reference value X is the seating point. In other words, it is determined whether the seating point has been reached based on the amount of change in the output torque per unit rotation angle. Therefore, as shown in FIG. 4, the case where the container 1 indicated by the broken line is wet and the case where the container 1 indicated by the solid line is wet
The output torque differs depending on the difference in the frictional force of the screw between the cap 5 and the container 1 depending on when the is dry, but the point at which the output torque sharply changes is determined to be the seating point. Thereby, regardless of whether the container 1 or the cap 5 is wet or dry, it can be determined at an accurate timing that the container 1 or the cap 5 has reached the seating point. Therefore, when the cap 5 is rotated by a predetermined rotation angle from the seating point, regardless of whether the container 1 or the cap 5 is dry or wet, the tightened state of the cap 5 is fixed and the screwed state is stabilized. Can be done.

FIG. 7 shows a method of determining a seating point in the above-described conventional method. In this conventional method, a point in time when the output torque exceeds a predetermined threshold value is determined as a seating point.
Therefore, when the container 1 is wet as indicated by the broken line, the frictional force between the packing 9 and the upper end of the container 1 is small, and therefore, compared to the case where the container 1 indicated by the solid line is dry. The timing to reach the threshold will be delayed. As described above, conventionally, when the container 1 is dry and when the container 1 is wet, the timing at which the threshold value is reached is shifted, so that it is impossible to accurately determine that the container 1 has reached the seating point. It was pointed out. In contrast, in the above-described embodiment, whether the container 1 or the cap 5 is dry or wet can be determined at an accurate timing that the seat 1 has reached the seating point.

By the way, in this embodiment, the cap 5
When a beret cap is formed when the cap 5 is screwed into the upper end of the mouth 1a of the container 1, immediately after the cap 5 is fitted to the upper end of the mouth 1a of the container 1 and the cap 5 is rotated,
After the output torque increases sharply, it suddenly decreases (see FIG. 8). Therefore, even when this beret cap occurs, the rate of change R exceeds the reference value X as shown in FIG. 9, and in this case, the user simply sits down because the rate of change R exceeds the reference value X. It is inconvenient to determine that the point has been reached. Therefore, in this embodiment, the output torque increases when the beret cap is generated immediately after the cap 5 is fitted to the container 1, and if the cap has a single turn, the output torque increases during at least one rotation. When the rate of change R exceeds the reference value X immediately after the cap 5 is fitted to the container 1, this is ignored. Therefore, the processing step S2 in FIG.
In the subsequent processing step S3, the control device 8 starts counting pulses after the torque motor 3 is driven and checks whether or not the predetermined number of pulses have been counted, that is, whether or not the cap 5 has rotated by a predetermined rotation angle. Like that. In the processing step S3, when it is confirmed that the cap is not rotated by the predetermined rotation angle, it is determined that the change rate R is a change caused by the beret cap, and the process returns to the previous step to perform the processing. On the other hand, the control device 8 determines that the vehicle has reached the seating point when it has been rotated by the predetermined rotation angle. The processing step S3
In the above, it is checked whether or not the motor has rotated by a predetermined rotation angle since the torque motor 3 was driven.
Instead, it may be confirmed whether or not a predetermined time has elapsed after driving the torque motor 3. Further, the processing step S3 in FIG. 6 is not always necessary and may be omitted.

(Second Embodiment) Next, FIG. 10 shows a second embodiment relating to the processing of the control device 8. In the second embodiment, the order of the processing steps S2 and S3 in the first embodiment shown in FIG. 6 is reversed. That is, when the control unit 8A drives the torque motor 3 (S
1) A pulse is input from the rotary encoder 6 to the control device 8 for each unit rotation angle dθ. In this embodiment, thereafter, it is confirmed whether or not the cap 5 has been rotated by a predetermined rotation angle after driving the torque motor 3 (S
2). If the cap 5 is not rotated by the predetermined rotation angle, the same processing is performed again. On the other hand, when it is confirmed that the cap 5 has been rotated by the predetermined rotation angle, the process proceeds to the next processing step S3. Then, in this processing step S3, for the first time, the calculating unit 8B of the control device 8 sets the output torque change rate R
And the comparing unit 8C compares the rate of change R with a reference value X stored in advance. As shown in FIG. 5, when the change rate R is less than the reference value X, the process returns to the previous step and the change rate R is compared with the reference value X again. On the other hand, as shown in FIG. 5, when the rate of change R exceeds the reference value X, the control device 8 determines that the time when the upper end of the mouth 1a of the container 1 is seated on the packing 9 I judge it as a point. Then, the control device 8 starts counting pulses by a built-in counter using this time as the pulse 1 (S1).
4). When the torque motor 3 is rotated from this point until the counter counts 70 pulses (S5), the controller 8A of the control device 8 stops the operation of the torque motor 3. In the second embodiment, the rate of change R is not determined immediately after the cap 5 is screwed into the container 1, so that even if a beret cap occurs, the seating point can be accurately determined. can do. In the processing step S2 in the second embodiment, it is checked whether the rotation has been performed by a predetermined rotation angle. Instead, a predetermined time has elapsed since the control unit 8A drives the torque motor 3. You may confirm whether it is. Even in such a second embodiment, the same operation and effect as in the first embodiment can be obtained.

(Third Embodiment) Next, FIG.
This shows a third embodiment relating to the processing of FIG. In the third embodiment, regardless of whether or not the beret cap has been generated, the output torque changes at a substantially constant value until the seat 5 reaches the seating point after the cap 5 is fitted to the container 1. Is focused on the fact that a substantially zero state is maintained. That is, in the third embodiment, when the control unit 8A of the control device 8 drives the torque motor 3 as described above (S1), the arithmetic unit 8 of the control device 8
B calculates the rate of change R of the output torque and checks whether or not the rate of change R has been rotated by a predetermined rotation angle with substantially zero (S2). If it does not rotate by the predetermined rotation angle, it returns to the previous position and performs the same processing again. On the other hand, when it is confirmed that the rotation rate has been rotated by the predetermined rotation angle while the rate of change R is substantially zero, the comparing unit 8C determines that the rate of change R
Is compared with a reference value X stored in advance (S3). If the rate of change R is less than the reference value X, the process returns to the previous step, and the rate of change R is compared with the reference value X again. On the other hand, the rate of change R
Exceeds the reference value X, the control device 8 determines that the time has reached the seating point where the upper end of the container 1 has come into contact with the packing 9. Then, the pulse at that time is set to 1, and the counting of the pulse is started by the built-in counter from this time (S4). If the torque motor 3 rotates until this counter counts 70 pulses (S5),
The control unit 8A of the control device 8 stops the operation of the torque motor 3. In the processing step S2 in the third embodiment, it is checked whether or not the rotation has been performed at a predetermined rotation angle while the change rate R is substantially zero. Instead, the change rate R is substantially changed. It may be determined whether the zero state has continued for a predetermined time. Even with such a configuration, the same operation and effect as those of the first and second embodiments can be obtained.

(Fourth Embodiment) Next, FIG.
14 shows a fourth embodiment relating to the processing of FIG. In the fourth embodiment, attention is paid to the fact that when the beret cap occurs, the output torque sharply increases and then the output torque sharply decreases. That is, in the fourth embodiment, when the control unit 8A of the control device 8 drives the torque motor 3 (S1), the calculation unit 8B of the control device 8 calculates the change rate R of the output torque, and the comparison unit 8C Is
This rate of change R is compared with a reference value X stored in advance (S
2). If the rate of change R is less than the reference value X, the process returns to the previous step and compares the rate of change R with the reference value X again. On the other hand, if the rate of change R exceeds the reference value X, the controller 8
Starts counting pulses by a built-in counter with the pulse at that time set to 1 (S3). Next, the control device 8 confirms whether the rate of change R is not negative (S4). If the rate of change R is negative, the process returns to the immediately preceding process, and the same process as the process process S2 is performed again. That is, in this case, it is determined that the beret cap has occurred, and the processing step S is started from the beginning.
Step 2 is performed. On the other hand, if the rate of change R is not negative, the control device 8 determines that the seating point has been reached, and rotates the cap 5 until the counter counts a predetermined number (70). Therefore, the operation of the torque motor 3 is stopped. Even in the fourth embodiment having such a configuration, the same operation and effect as those of the above-described embodiments can be obtained. In each of the above embodiments, the rotary encoder 6 inputs one pulse to the control device 8 each time the torque motor 3 is rotated once, but the rotary encoder 6 rotates the torque motor 3 at a predetermined angle of 1 degree or more or 1 degree or less. One pulse may be input to the control device 8 every time it is rotated. Further, the control device 8 stores the value one pulse before as the output torque input from the torque detector 7, but stores the value several pulses before as the output torque input from the torque detector 7. You may do it. Further, the reference value X is given a range, and the lower limit value of the reference value X is compared with the change rate R. When the change rate R exceeds the lower limit value of the reference value X, the seating point (FIG. J) is reached. In this case, when the change rate R exceeds the upper limit of the reference value X, the change rate R is ignored.

[0016]

As described above, according to the present invention, regardless of the difference between the cap and the container, the cap can be accurately rotated from the seating point by a predetermined rotation angle regardless of whether the container is wet or dry. Then, an effect of being screwed to the container is obtained.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a positional relationship between a cap and a container.

FIG. 3 is a cross-sectional view showing a positional relationship between a cap and a container at a seating point.

FIG. 4 is a diagram showing a relationship between output torque and a rotation angle of a cap in the embodiment shown in FIG. 1;

FIG. 5 is a diagram showing a relationship between a change rate R and a rotation angle of a cap in the embodiment shown in FIG. 1;

FIG. 6 is a diagram showing processing steps of the control device in the first embodiment shown in FIG. 1;

FIG. 7 is a diagram showing a relationship between output torque and elapsed time in a conventional method.

FIG. 8 is a diagram showing a relationship between output torque and a rotation angle of a cap when a beret cap occurs in the embodiment shown in FIG. 1;

FIG. 9 is a diagram showing the relationship between the rate of change R and the rotation angle of the cap when a beret cap occurs in the embodiment shown in FIG. 1;

FIG. 10 is a process chart showing a second embodiment of the present invention.

FIG. 11 is a process chart showing a third embodiment of the present invention.

FIG. 12 is a process chart showing a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Container holding mechanism 4 Capping head 5 Cap 6 Rotary encoder 7 Torque detector 8 Control device 9 Packing

Claims (6)

[Claims] 1. A capping method comprising: a capping head for detachably holding a cap; and a motor for rotating the capping head, wherein the cap held by the capping head is screwed to a container. The amount of change in output torque per unit rotation angle during rotation is determined, and the amount of change is compared with a predetermined reference value.If the amount of change exceeds the reference value, only the predetermined rotation angle is determined. A capping method comprising: rotating a cap to stop screwing the cap onto a container. 2. The method according to claim 1, wherein the change amount exceeds the reference value after the motor is driven and the cap is rotated by a predetermined rotation angle or before a predetermined time elapses. 2. The capping method according to claim 1, wherein the capping value is handled as not exceeding the reference value. 3. The system according to claim 1, wherein the cap is rotated by a predetermined rotation angle after the motor is driven, or the change amount is compared with the reference value after a predetermined time has elapsed. The capping method described. 4. When the motor is driven, the change amount is obtained, and after the change amount is substantially zero for a predetermined time or after a predetermined rotation angle, the change amount is determined. The capping method according to claim 1, wherein the method is compared with a reference value. 5. The capping method according to claim 1, wherein if the change amount becomes negative after the change amount exceeds the reference value, the change amount is handled as not exceeding the reference value. Method. 6. A capping head for detachably holding a cap, a motor for rotating the capping head, and a control device for controlling the rotation of the motor,
In a capping device in which a cap held by a capping head is screwed onto a container, a rotation detector that outputs a pulse signal for each unit rotation angle of the motor and a torque detection unit that detects an output torque of the motor are provided. A control unit that controls the operation of the motor; and a unit rotation when the motor is rotated based on a pulse signal output by the rotation detector and an output torque value output by a torque detection unit. A calculating unit for calculating a change amount of the output torque per angle; and a comparing unit for comparing the change amount obtained by the calculating unit with a predetermined reference value, wherein the change amount obtained by the calculating unit is predetermined. When the reference value is exceeded, the control unit rotates the motor by the number of pulses corresponding to a predetermined rotation angle from the pulse signal at the time when the reference value is exceeded. Capping and wherein the terminating the screwing to the container of the cap.