JP6874337B2 - Container leak inspection device and leak inspection method - Google Patents

Description

The present invention relates to an inspection device and an inspection method for inspecting a leak in a container on the downstream side of a container production line.

On the downstream side of the container manufacturing line for synthetic resin bottles and cans, a leak inspection is performed to inspect whether the manufactured container has a predetermined airtightness. In such a leak inspection, an inspection head is attached to the mouth of the container and pressurized air is supplied into the closed container to apply inspection pressure to the inside of the container and then maintain the closed state for a certain period of time. Then, the presence or absence of leakage is determined from the amount of pressure drop in the container internal pressure detected during that period.

In the prior art described in Patent Document 1 below, for a bottle made of synthetic resin, an inspection head is attached to the bottle mouth, the supply valve is opened only for a predetermined period, and the internal pressure of the bottle immediately after the supply valve is closed. Is used as the reference internal pressure, and it is checked whether or not the reference internal pressure exceeds the predetermined first threshold value. If the reference internal pressure exceeds the first threshold value, the air-sealed state of the bottle is maintained for a certain period of time to reduce the internal pressure of the bottle. The amount of pressure drop from the reference internal pressure after a certain period of time is measured by a differential pressure sensor, and if the amount of pressure drop does not exceed the predetermined second threshold value, the bottle is judged to be non-defective (no leak). ..

JP-A-2009-109259

On the downstream side of the container manufacturing line, the temperature of the container changes from a high temperature state to a room temperature gradually. For example, in the case of a synthetic resin bottle, the temperature of the bottle immediately after being taken out from the blow mold is about 40 to 50 ° C at the body, and 30 ° C at the entrance of the leak inspection device on the downstream side of the container manufacturing line. It will be about. After that, the temperature of the bottle drops to room temperature (about 25 ° C.) in the process of being transported.

When performing a leak inspection on the downstream side of the container manufacturing line, it is necessary to fully consider the above-mentioned temperature change of the container. Since the amount of pressure decrease from the reference internal pressure becomes small when the temperature of the container is high, it is necessary to set the threshold value in the above-mentioned leak inspection to a value in consideration of the temperature of the container.

The temperature of the bottle body that flows into the leak inspection device is about 30 ° C as described above during continuous production, but if the container production line is temporarily stopped and restarted, bottles near room temperature may flow. is there. For this reason, it is necessary to set a wide threshold value corresponding to the entire temperature range, or to make complicated adjustments such as changing the threshold value appropriately according to the temperature of the bottle at the inlet of the leak inspection device, so that highly productive leak inspection can be performed. There was a problem that could not be done.

The present invention has been proposed to address such problems. That is, an object of the present invention is to perform a leak inspection of a container on the downstream side of a container production line with high productivity and high accuracy without considering a change in the container temperature.

In order to solve such a problem, the present invention has the following configurations.
Among the containers aligned and conveyed from the container manufacturing line, the supply pressure is simultaneously sent to the inspection head mounting portion that mounts the inspection heads at the mouths of the plurality of containers and the inspection heads that are mounted on the plurality of containers. , A pressure supply unit that uses the pressure in the plurality of sealed containers as an inspection pressure, and a leak that detects a change in pressure over time in the plurality of sealed containers and determines a leak in the plurality of containers. A determination unit is provided, and the leak determination unit is provided with a differential pressure sensor that detects a differential pressure in a pair of the plurality of containers, and makes a leak determination based on the output of the differential pressure sensor. Leak inspection device for containers.

The leak inspection device for containers having such characteristics detects the differential pressure in the containers and determines the leak for the containers that are aligned and transported from the container production line and are paired with a plurality of containers. .. Since the container temperatures of a pair of multiple containers in the aligned and transported container are almost the same, the productivity is high by detecting the differential pressure in those containers without considering the change in the container temperature. Highly accurate leak judgment can be performed.

In addition, since the range of pressure change detected in the paired container is small regardless of the size of the container, a minute pressure can be obtained by making the range of this small pressure change correspond to the full range of the differential pressure sensor. Changes can be detected with high sensitivity. This also makes it possible to perform highly accurate leak determination.

It is explanatory drawing which showed the structural example of the leak inspection apparatus of the container which concerns on embodiment of this invention. It is explanatory drawing which showed the installation example of the leak inspection apparatus of the container which concerns on embodiment of this invention. It is explanatory drawing which showed the determination example of the presence or absence of a leak by the leak inspection apparatus of the container which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings based on the case where a leak inspection is performed on a pair of containers. Hereinafter, the same reference numerals in different figures indicate parts having the same function, and duplicate description in each figure will be omitted as appropriate.

As shown in FIG. 1, the container leak inspection device (hereinafter, leak inspection device) 1 according to the embodiment of the present invention includes an inspection head mounting unit 2, a pressure supply unit 3, and a leak determination unit 4. Here, the inspection target is a pair of containers W1 and W2 that have been aligned and conveyed from the container production line. The target containers W1 and W2 may be any container as long as the airtightness can be ensured by closing the mouth, and various containers such as synthetic resin bottles, metal cans, metal bottle cans, and pouches can be targeted. .. Then, in the present embodiment, the leak inspection device 1 simultaneously inspects a pair of neighboring containers W1 and W2 among the containers aligned and conveyed from the container production line, and these container temperatures. Is assumed to be about the same.

The inspection head mounting portion 2 has a function of mounting the inspection heads 20 and 21 on the mouths of the pair of containers W1 and W2 to be inspected, respectively. The inspection heads 20 and 21 seal the mouths of the containers W1 and W2, respectively, and connect the ends of the pressure supply pipes 30 and 31 connected to the pressure supply unit 3 and the pressure detection pipes 40 and 41 connected to the leak determination unit 4. Has been done. As a result, when the inspection head 20 (21) is attached to the mouth of the container W1 (W2), the mouth is sealed and the ends of the pressure supply pipe 30 (31) and the pressure detection pipe 40 (41) are closed. Will communicate with the container W1 (W2).

Explaining a specific configuration example of the inspection head mounting portion 2 shown in FIG. 1, the inspection head mounting portion 2 includes air cylinders 22 and 23 for raising or lowering the inspection heads 20 and 21. Pipes 24A and 24B for operating the air cylinder are connected to the air cylinder 22, and pipes 24C and 24D branched from the pipes 24A and 24B are connected to the air cylinder 23, respectively. A flow path switching valve 25 is connected between the pipe 24E connected to the pressure supply source via the pressure adjusting valve 26 and the pipes 24A and 24B, and the flow path switching valve 25 can be switched and operated. , The air cylinders 22 and 23 operate to raise or lower the inspection heads 20 and 21. The mechanism for raising or lowering the inspection heads 20 and 21 is not limited to the above-mentioned air cylinder, and other actuators such as an electric cylinder may be used.

The pressure supply unit 3 simultaneously sends the supply pressure to the inspection heads 20 and 21 mounted on the pair of containers W1 and W2, respectively, and raises the pressure in the pair of sealed containers W1 and W2 to the inspection pressure. As a more specific configuration shown in FIG. 1, the pressure supply unit 3 includes flow path switching valves 32 and 33 connected to the pressure supply pipes 30 and 31. A pipe 35 connected to the pressure supply source via the pressure adjusting valve 34 and a pipe 36 branched from the pipe 35 are connected to the flow path switching valves 32 and 33, respectively. By simultaneously switching the flow path switching valves 32 and 33 to the inspection heads 20 and 21, the supply pressure is simultaneously sent to the inspection heads 20 and 21. Then, after a predetermined time elapses and the internal pressure of the container reaches the inspection pressure, the flow path switching valves 32 and 33 are simultaneously switched to the closed side, the pressure supply is stopped, and the closed state is established.

The supply pressure in the pressure supply unit 3 is preferably set higher than the inspection pressure applied to the pair of containers W1 and W2, and by setting the supply pressure higher than the inspection pressure, the pair It becomes possible to shorten the pressurizing time in the containers W1 and W2.

The leak determination unit 4 detects a change in pressure over time in the pair of containers W1 and W2 sealed by the inspection heads 20 and 21, and determines the leak of the pair of containers W1 and W2. Here, the leak determination unit 4 includes a differential pressure sensor 42 that detects the differential pressure in the pair of containers W1 and W2. The differential pressure sensor 42 is connected to the other ends of the pressure detection pipes 40 and 41, one end of which is connected to the inspection heads 20 and 21.

As a more specific configuration of the leak determination unit 4 shown in FIG. 1, the other ends of the pressure detection pipes 40 and 41 are further branched and connected to the direct pressure sensors 43 and 44, and are directly connected to the differential pressure sensor 42. The pressure detection unit 45 is composed of the pressure sensors 43 and 44. The direct pressure sensors 43 and 44 directly detect the internal pressure of each of the pair of containers W1 and W2, and the other ends of the pressure detection pipes 40 and 44 are branched and connected to the direct pressure sensors 43 and 44. The differential pressure in the pair of containers W1 and W2 detected by the differential pressure sensor 42 and the internal pressure of each of the pair of containers W1 and W2 detected by the direct pressure sensors 43 and 44 can be detected at the same time.

Further, the leak determination unit 4 includes an arithmetic processing unit 46, and the outputs of the differential pressure sensor 42 and the direct pressure sensors 43 and 44 are input to the arithmetic processing unit 46. The arithmetic processing unit 46 determines whether or not there is a leak in the containers W1 and W2 based on the outputs of the differential pressure sensor 42 and the direct pressure sensors 43 and 44.

Here, the pressure detection pipes 40 and 41 connected to the leak determination unit 4 are connected to the inspection heads 20 and 21 in a state of being separated from the pressure supply pipes 30 and 31 connected to the pressure supply unit 3. By connecting the pressure supply pipes 30 and 31 and the pressure detection pipes 40 and 41 to the inspection heads 20 and 21 in this way, the hunting time generated during the operation of the flow path switching valves 32 and 33 can be shortened. it can.

FIG. 2 shows an installation example of the leak inspection device 1. The leak inspection device 1 targets a pair of neighboring containers W1 and W2 among the containers W aligned and conveyed in a row by a transfer device 60 such as a conveyor, and an inspection head is provided along the transfer direction of the containers W. While moving 20 and 21, the leak inspection of the container W is sequentially performed. Therefore, the leak inspection device 1 is provided with a guide rail 50 along the transport direction of the transport device 60, and includes moving mechanisms 51 and 52 for moving the inspection heads 20 and 21 along the guide rail 50.

The moving mechanisms 51 and 52 move the inspection heads 20 and 21 in synchronization with the transport of the pair of containers W1 and W2, and move the inspection heads 20 and 21 in the direction opposite to the transport direction. After the inspection heads 20 and 21 are attached to the pair of containers W1 and W2, the moving mechanisms 51 and 52 move the inspection heads 20 and 21 at the same speed as the moving speed of the transport device 60, and the pair of containers W1 and W1 move. After the inspection heads 20 and 21 are separated from W2, the initial position return operation is started, the moving speed is increased and the inspection heads 20 and 21 are moved in the direction opposite to the transport direction, and the state becomes a standby state. Although not shown, a sensor for detecting the container W is arranged on the transport device 60, and the inspection heads 20 and 21 are attached to the container W and moved by the moving mechanisms 51 and 52 at the timing when the container W is detected. It may be configured individually. As a result, the inspection heads 20 and 21 can be reliably attached to the container even if the pitch of the container W varies.

Next, a leak inspection method by the leak inspection device 1 will be described with reference to FIG. To start the inspection, first, the inspection head mounting portions 2 mount the inspection heads 20 and 21 on the mouths of the pair of containers W1 and W2 (inspection head mounting step). In the example shown in FIG. 2, the movements of the moving mechanisms 51 and 52 are synchronized with the movement of the transport device 60, the air cylinders 22 and 23 are operated by the switching operation of the flow path switching valve 25, and the inspection heads 20 and 21 are operated. Lower.

When the installation of the inspection heads 20 and 21 is completed, the pressure supply unit 3 simultaneously sends the supply pressure to the inspection heads 20 and 21 to pressurize the inside of the containers W1 and W2, and the pressure in the containers W1 and W2 becomes the inspection pressure. Raise (pressure supply process). The supply pressure is applied by simultaneously switching the flow path switching valves 32 and 33 in the pressure supply unit 3, switching the flow path switching valves 32 and 33 to the open side to turn on the supply pressure, and then a predetermined time elapses. After that, the flow path switching valves 32 and 33 are switched to the closed side to turn off the supply pressure, and the container internal pressure is maintained at the inspection pressure.

As described above, the applied supply pressure is preferably set higher than the inspection pressure, and by setting the supply pressure higher, the pressurization time can be shortened. After applying the inspection pressure, a predetermined equilibrium period is provided to stabilize the pressure state in the containers W1 and W2, and then the leak determination step described later is performed. By separating 41 on the secondary side of the containers W1 and W2, the equilibrium period can be shortened.

After that, the amount of pressure change with time in the pair of sealed containers W1 and W2 is detected, and the leak determination of the pair of containers W1 and W2 is performed (leak determination step). Here, the amount of pressure change is detected by the outputs of the differential pressure sensor 42 and the direct pressure sensors 43 and 44. The leak determination unit 4 mainly detects the differential pressure in the pair of containers W1 and W2 by the differential pressure sensor 42, and makes a leak determination based on the differential pressure. As an auxiliary, the direct pressure sensors 43 and 44 The internal pressure of each of the containers W1 and W2 is detected by the output of. The direct pressure sensors 43 and 44 can be omitted as appropriate depending on the inspection situation.

In the leak determination step, first, the internal pressures of the containers W1 and W2 at the end of the pressurization time are measured by the direct pressure sensors 43 and 44, and if the inspection pressure is not reached, it is determined that there is a large leak. .. When the inspection pressure is reached, the pressure detected after a lapse of time t1 from the start of the inspection (the pressure difference between the pressure at point A or A'and the pressure at point C or C'in the figure) and then Δt time have elapsed. , The amount of pressure change is determined by comparing the pressure detected after a lapse of time t2 from the start of the inspection (the pressure at point B or B'in the figure and the differential pressure at point D or D').

The leak determination based on the output of the differential pressure sensor 42 is a value obtained by subtracting the differential pressure detected at the C point or the C'point from the differential pressure detected at the D point or the D'point shown in the differential pressure graph of FIG. The pressure change amount of the differential pressure) is compared with the set threshold value, and when the pressure change amount of the differential pressure exceeds the threshold value, it is determined that there is a leak in one of the containers W1 and W2, and the threshold value is not exceeded. In this case, it is determined that there is no leak in both the containers W1 and W2. In the graph of the differential pressure in FIG. 3, the inspection waveform of the differential pressure when there is no leak in both the containers W1 and W2 is shown by a solid line, and the inspection waveform of the differential pressure when there is a leak in one of the containers W1 and W2 is shown. It is shown by a broken line. If there is no leak in both containers W1 and W2, the pressure change amount of the differential pressure is almost 0 Pa, but if there is a leak in one of the containers W1 and W2, the pressure change amount of the differential pressure elapses over time. It grows with.

When it is determined that there is a leak, which side of the containers W1 and W2 has the leak can be determined by the positive or negative of the output of the differential pressure sensor 42. Further, although it is an extremely rare case, if there is an equivalent leak in both containers W1 and W2, the pressure change amount of the differential pressure does not exceed the threshold value. In order to avoid erroneous determination in such a case, direct pressure sensors 43 and 44 are provided as auxiliary. The presence or absence of leaks in the individual containers W1 and W2 can be determined by the outputs of the direct pressure sensors 43 and 44.

The leak determination based on the output of the direct pressure sensors 43 and 44 is the value obtained by subtracting the pressure detected at the point B or B'from the pressure detected at the point A or A'shown in the graph of the direct pressure in FIG. Compared with the set threshold value, if the threshold value is exceeded, it is determined that there is a leak, and if the threshold value is not exceeded, it is determined that there is no leak. As shown in FIG. 3, in the direct pressure inspection waveform, when there is no leak, the pressure change amount is almost 0 Pa as shown by the solid line, and when there is a leak, the pressure change amount is shown by the broken line. Will be a large value.

As shown in FIG. 3, the flow path switching valve 25 is switched to lower the inspection heads 20 and 21, and after performing the pressure supply step and the leak determination step, the inspection heads 20 and 21 are moved from the containers W1 and W2. The inspection time for the pair of containers W1 and W2 is until the inspection heads 20 and 21 are prepared for lowering with respect to the next pair of containers.

In the example shown in FIG. 2, after the inspection heads 20 and 21 are attached to the pair of containers W1 and W2, the pressure supply process and the leak occur while the inspection heads 20 and 21 are moved according to the transportation of the containers W1 and W2. Perform the determination process. Then, after the leak determination step, the inspection heads 20 and 21 are separated from the pair of containers W1 and W2 and returned to the initial positions, and move at an increased moving speed in the direction opposite to the transport direction of the pair of containers W1 and W2. Then, the position is returned to the initial position F, and the standby state is set.

According to the leak inspection method using such a leak inspection device 1, a pair of containers W1 and W2 having substantially the same container temperature, which are aligned and conveyed from the container production line, are subject to leak determination based on the differential pressure in the containers. Therefore, the leak determination can be performed without considering the change in the container temperature. This eliminates the need for adjusting the threshold value in consideration of changes in the container temperature, and enables highly productive leak determination.

Further, since the absolute value of the pressure change amount over time is small for the differential pressure in the pair of containers W1 and W2, this small change is made to correspond to the full range of the differential pressure sensor 42, and the pressure change is detected with high sensor sensitivity. can do. As a result, highly accurate leak determination can be realized, and leaks due to extremely small pinholes can be detected without being overlooked.

Further, as in the installation example shown in FIG. 2, since the leak inspection device 1 can be incorporated in the container transport process, the leak inspection space can be saved, and the tact time of the container transport process can be saved. Since leak inspection using the above is possible, high productivity can also be obtained.

The leak inspection device 1 shortens the pressurization time by setting the supply pressure higher than the inspection pressure, and separates the pressure supply pipes 30 and 31 and the pressure inspection pipes 40 and 41 for the inspection head. By connecting to 20 and 21, the equilibrium period after pressure supply can be set short, so that the elapsed time Δt for detecting the pressure change amount can be set long within a limited inspection time range. This makes it possible to perform leak determination with high certainty.

As described above, the embodiment of the present invention has been described in the case of performing leak inspection on a pair of neighboring containers W1 and W2, but it is also possible to perform leak inspection on three or more containers W. Is. In that case, the paired combination is free. For example, in the three containers W1, W2, W3, the paired combination may be W1-W2, W2-W3, or W1-W2, W1-W3. In this way, when the number of processed containers increases, each part of the leak inspection device (inspection head mounting unit 2, pressure supply unit 3, leak determination unit 4) is appropriately added according to the number of processed containers.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the design changes, etc. within the range not deviating from the gist of the present invention, etc. Even if there is, it is included in the present invention. Further, each of the above-described embodiments can be combined by diverting the technologies of each other as long as there is no particular contradiction or problem in the purpose and configuration thereof.

1: Leak inspection device,
2: Inspection head mounting part, 3: Pressure supply part, 4: Leak judgment part,
20, 21: Inspection head, 22, 23: Air cylinder,
24A-24E, 35, 36: Piping,
25, 32, 33: Flow path switching valve, 26, 34: Pressure regulating valve,
30, 31: Pressure supply piping, 40, 41: Pressure detection piping, 42: Differential pressure sensor,
43, 44: Direct pressure sensor, 45: Pressure detection unit, 46: Arithmetic processing unit,
50: Guide rail, 51, 52: Moving mechanism, 60: Conveyor (conveyor),
W1, W2: Container

Claims (5)

Among the containers lined up and transported from the container manufacturing line, the inspection head mounting part that mounts the inspection head on the mouth of multiple containers, and the inspection head mounting part.
A pressure supply unit that simultaneously sends a supply pressure to the inspection head mounted on each of the plurality of containers and makes the pressure in the plurality of sealed containers the inspection pressure.
It is provided with a leak determination unit that detects a change in pressure over time in the plurality of sealed containers and determines a leak in the plurality of containers.
The leakage determination unit includes a differential pressure sensor for detecting the differential pressure in the container to be paired of the plurality of containers, have rows leakage determination based on the output of the difference pressure sensor, and said plurality of containers each A container leak inspection device including a direct pressure sensor that detects the internal pressure of the container at the same time as the differential pressure. The leak inspection device for a container according to claim 1, wherein the pressure supply pipe connected to the pressure supply unit and the pressure detection pipe connected to the leak determination unit are separated from each other and connected to the inspection head. The inspection head mounting portion includes a moving mechanism for moving the inspection head along the transport direction of the plurality of containers.
The moving mechanism moves the inspection head mounted on the plurality of containers in synchronization with the transportation of the plurality of containers, and the inspection head detached from the plurality of containers after the inspection is referred to as the transport direction. The container leak inspection device according to claim 1 or 2 , wherein the container moves in the opposite direction. Among the containers lined up and transported from the container manufacturing line, the inspection head mounting process in which the inspection heads are mounted on the mouths of multiple containers,
A pressure supply step in which a supply pressure is simultaneously sent to the inspection heads mounted on the plurality of containers to make the pressure in the plurality of sealed containers the inspection pressure.
It has a leak determination step of detecting a pressure change over time in the plurality of sealed containers and determining a leak of the plurality of containers.
In the leakage determination process, by detecting the differential pressure in the container to be paired of the plurality of containers, have rows leakage determination based on the difference pressure and a plurality of containers each of internal pressure, the differential pressure A container leak inspection method characterized by simultaneous detection. The pressure supply step and the leak determination step are performed while moving the inspection head mounted on the plurality of containers in synchronization with the transportation of the plurality of containers.
The leak inspection of a container according to claim 4 , wherein after the leak determination step, the inspection head is separated from the plurality of containers and moved in a direction opposite to the transport direction of the plurality of containers. Method.

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