JP4848503B2 - PET bottle leak inspection device - Google Patents

Description

  The present invention relates to a PET bottle leak inspection apparatus, and more particularly to an apparatus for detecting whether a PET bottle has a defect such as a pinhole before filling the PET bottle with a liquid such as a beverage. The present invention relates to a PET bottle leak inspection apparatus that detects whether compressed air leaks from a PET bottle by filling with compressed air.

  Conventionally, PET bottles (PET bottles), which are lightweight plastic bottles, are frequently used for filling soft drinks and the like. Before filling a PET bottle with a liquid such as a beverage, it is necessary to inspect the PET bottle for defects such as pinholes. Conventionally, a PET bottle leak inspection apparatus has been used. In this PET bottle leak inspection device, the PET bottle is transferred by a star wheel and supplied to the main rotor, the PET bottle is placed on the container table of the main rotor, and the pressure head is lowered to open the PET bottle mouth. The mouth of the PET bottle is sealed with the packing of the pressure head, and in this state, compressed air is supplied from the compressed air source into the PET bottle via the pressure head. Then, after supplying compressed air of a predetermined pressure into the PET bottle, the inside of the PET bottle is sealed, and the PET bottle is transported by the main rotor while the PET bottle is transported by the pressure sensor connected to the pressure head after a predetermined time has passed. The pressure is measured and leaks from the plastic bottle are detected.

Conventionally, as described in Patent Document 1, as a switching device for a piping system that feeds compressed air into a PET bottle, a spool type solenoid valve has been used mainly for high-speed response in order to keep the initial pressure value constant. is doing. In this case, the spool type electromagnetic valve is opened and compressed air of a predetermined pressure is sent from the compressed air source into the PET bottle, and then the spool type electromagnetic valve is closed to seal the inside of the PET bottle.
JP 2004-205453 A

  The above-described spool-type solenoid valve is a valve that opens and closes a flow path by a spool that moves in an axial direction in a cylindrical sleeve. In the mechanical engineering dictionary (published by Asakura Shoten Co., Ltd.), Since it is a sliding valve that moves parallel to the opening surface of the control orifice, the flow cannot be completely blocked, but the operating force of the valve is small because the force acting in the axial direction can be almost balanced. Except for a small range of valve opening, the flow characteristics of the valve have many advantages, such as being less susceptible to viscosity, so spool valves are exclusively used for electro-hydraulic servo valves. As described above, the spool valve is easy to operate and highly versatile, but the sealing performance is not perfect, and the compressed air in the PET bottle leaks slightly through the spool type solenoid valve. There is a cormorant problem. Due to this leak, there is a problem in that a defective product such as a pin pole may be erroneously detected despite a good plastic bottle. And the continuous use of the spool type solenoid valve has the problem that the sealing performance is further lowered and the frequency of false detection increases, and the operation of the leak inspection apparatus is stopped due to the downstream process of the leak inspection apparatus. There is a problem that the frequency of false detection is further increased by continuing leakage from the spool-type solenoid valve, for example, when it is unavoidable.

  The present invention has been made in view of the above circumstances, and even when a spool type solenoid valve capable of high-speed response is used, the sealing performance, which is a drawback of the spool type solenoid valve, is incomplete. An object of the present invention is to provide a leak inspection apparatus for a PET bottle that can prevent erroneous detection that determines that a non-defective product is a defective product.

In order to achieve the above object, a PET bottle leak inspection apparatus according to the present invention supports a plurality of PET bottles and conveys them on a predetermined circumference, and is installed in the main rotor at the mouth of the PET bottle. In a PET bottle leak inspection apparatus having a sealing member that engages and seals the mouth portion, and includes a pressurizing head that supplies gas into the PET bottle, the pressurizing head is connected via a first electromagnetic valve. A first check valve that is connected to a compressed air source and prevents a backflow of compressed air from the pressure head side to the first electromagnetic valve side between the pressure head and the first electromagnetic valve; Is connected to the second check valve, and a second solenoid valve is provided for applying a back pressure for closing the second check valve to the second check valve, and one port of the second solenoid valve is connected to the atmosphere. The back pressure applied to the second check valve is communicated with the second check valve. By dividing, it is characterized in that the compressed air in the PET bottle can be discharged to the outside through the second check valve and the second solenoid valve.

  According to the present invention, when the seal between the seal member of the pressurizing head and the mouth of the PET bottle is completed, the first electromagnetic valve is opened, and the pressurizing head and the compressed air source are communicated with each other. A predetermined amount of compressed air is supplied into the bottle, and the PET bottle is filled with compressed air having a predetermined pressure. Then, the first solenoid valve is closed. At this time, even if the sealing performance of the first electromagnetic valve is not perfect, the backflow of compressed air from the pressure head side to the first electromagnetic valve side is prevented between the first electromagnetic valve and the pressure head. Since the 1 check valve is provided, the compressed air in the PET bottle does not leak from the first electromagnetic valve. At this time, back pressure is applied to the second check valve via the second solenoid valve, and the second check valve remains closed, from the pressure head side to the second solenoid valve side. Compressed air does not flow. In this state, the plastic bottle is transported along the circumference of the main rotor, and the pressure in the plastic bottle is measured by the pressure sensor after a predetermined time during the transportation. If the pressure in the PET bottle after the lapse of the predetermined time is the same as the initial pressure, it is determined that there is no leak from the PET bottle and there is no defect such as a pinhole in the PET bottle.

According to one aspect of the present invention, the second electromagnetic valve is connected to the compressed air source, and the back pressure is applied to the second check valve .
According to one aspect of the present invention, the first solenoid valve and the second solenoid valve are formed of spool type solenoid valves.

The present invention has the following effects.
1) Since a first check valve for preventing a backflow of compressed air from the pressure head side to the first electromagnetic valve side is provided between the first electromagnetic valve and the pressure head, the inside of the PET bottle The compressed air does not leak from the first solenoid valve. Therefore, even if a spool type solenoid valve with incomplete sealing performance is used as the first solenoid valve, it is possible to prevent erroneous detection that determines that a non-defective product is defective due to incomplete sealing performance.
2) After the leak test is completed, the second solenoid valve is operated to release the back pressure of the second check valve, so that the compressed air in the PET bottle is discharged to the outside via the second check valve and the second solenoid valve. Can be exhausted. Further, by releasing the back pressure of the second check valve by the second solenoid valve, the compressed air in the PET bottle is released to the atmosphere, so that the deformation of the PET bottle due to the internal pressure during a long stay is prevented. Can do.
3) When a pressure higher than the back pressure for closing the second check valve is applied to the second check valve, the second check valve opens and acts as a safety valve. Even when an abnormally high pressure is applied, this high pressure can be released via the second check valve.
4) Since the first check valve itself acts as a regulator, the rush pressure (rapid increase in pressure) when supplying air to the PET bottle is greatly reduced, so that the pressure in the PET bottle becomes stable. This speeds up the time, and the container internal pressure can be sealed at a higher speed. In addition, the burden on the pressure sensor is reduced by reducing the maximum pressure applied to the pressure sensor used during pressure measurement.

Hereinafter, an embodiment of a PET bottle leak inspection apparatus according to the present invention will be described with reference to FIGS.
FIG. 1 is a plan view showing the overall configuration of a PET bottle leak inspection apparatus. As shown in FIG. 1, the PET bottle leak inspection apparatus includes an inlet star wheel 2 that carries a PET bottle 1 to be inspected into a main rotor 10, and an outlet star wheel that carries the PET bottle 1 after inspection out of the main rotor 10. 3 is provided. On the upstream side of the inlet star wheel 2, guide rails 5 and 5 for carrying the plastic bottle 1 into the inlet star wheel 2 are installed. Further, guide rails 6 and 6 for carrying out the plastic bottle 1 from the outlet star wheel 3 are installed on the downstream side of the outlet star wheel 3. The inlet side guide rails 5 and 5 and the outlet side guide rails 6 and 6 are downwardly inclined in the traveling direction. Star wheel guides 7, 8, 9 are provided on the outer peripheral side of the inlet star wheel 2, the outer peripheral side of the main rotor 10, and the outer peripheral side of the outlet star wheel 3, respectively.

  FIG. 2 is a diagram showing a detailed structure of the main rotor, and is a cross-sectional view of the main rotor. As shown in FIG. 2, the main rotor 10 is rotationally driven by a driving source (not shown) and is integrally connected to the upper and lower rotary shafts 12 by a coupling 11, and is fixed to the rotary shaft 12 and integrated with the rotary shaft 12. A rotating base plate 13, a support plate 14 fixed to the upper end of the rotating shaft 12 and rotating integrally with the rotating shaft 12, and a plurality of plates that move up and down and engage with the mouth 1m of the PET bottle 1 during a leak inspection The pressure head 35 is provided. The lower portion of the rotary shaft 12 is supported by a support frame 19 via a bearing housing 18 in which a bearing 17A is provided, and the rotary shaft 20 is disposed coaxially with the rotary shaft 12 above the rotary shaft 12. The rotary shaft 20 is supported in a hollow shaft 21, and the hollow shaft 21 is inserted into a bearing housing 22 that holds the bearing 17 </ b> B and is fixed to the support plate 14. A through hole 20a is formed in the rotary shaft 20, and a power cable 100 connected to an external power source is passed through the through hole 20a, and the first spool type electromagnetic valve EV1, the second spool type electromagnetic valve EV2, and the pressure Electric power is supplied to the sensor S.

  The main rotor 10 includes a neck ring star wheel 25 that supports the neck ring 1a of the plastic bottle 1 and a shoulder pressing star wheel 26 that supports the shoulder of the plastic bottle 1, and the neck ring star wheel 25 and the shoulder pressing star wheel. 26 is fixed to the base plate 13 via a support 27. A plurality of arc-shaped pockets 26 a that engage with the neck ring 1 a of the plastic bottle 1 and support the neck ring 1 a are formed on the outer peripheral portion of the neck ring star wheel 25 (see FIG. 1). A plurality of arc-shaped pockets (not shown) that engage with the shoulder portion of the plastic bottle 1 are formed on the outer peripheral portion of the shoulder pressing star wheel 26. Further, on the outer peripheral side of the neck ring star wheel 25, the star wheel guide 8 is provided for preventing the plastic bottle 1 from jumping out and positioning the plastic bottle. The star wheel guide 8 may be replaced with a belt supported by a pulley and rotatable. The neck ring star wheel 25, the inlet star wheel 2 and the outlet star wheel 3 are arranged in the same plane.

  A plurality of guide bars 28 are erected on the support plate 14, and these guide bars 28 are arranged at predetermined intervals on a predetermined circumference. A slide member 30 having a cam follower 29 is attached to each guide bar 28 so as to be movable up and down. A pressure head 35 is fixed to each slide member 30, and the pressure head 35 and the slide member 30 move up and down integrally.

  On the other hand, a fixed plate 32 is fixed to the hollow shaft 21 provided on the outer peripheral side of the rotary shaft 20, and a cylindrical body 34 is fixed to the fixed plate 32 via a support 33. The upper end surface of the cylindrical body 34 constitutes a cam surface 34 a, and the cam surface 34 a is formed with a height difference over the entire circumference of the upper end surface of the cylindrical body 34. When the support plate 14 rotates with the rotation of the main rotor 10, the cam follower 29 of each slide member 30 moves up and down following the cam surface 34a, whereby the slide member 30 and the pressure head 35 are moved to the guide bar. It moves up and down along 28.

  FIG. 3 is a schematic diagram showing a compressed air supply system for supplying compressed air to the pressure head 35 and the pressure head 35. A plurality of pressure heads 35 (36 in the present embodiment) are arranged on a predetermined circumference of the main rotor 10, and each pressure head 35 is supported by a slide member 30 as shown in FIG. A rod 36, a pressure head main body 37 fixed to the lower end of the support rod 36, a packing 38 that is adhered to the lower end surface of the pressure head main body 37 and constitutes a seal member, and projects downward from the pressure head main body 37. The substantially hemispherical nozzle 39 is provided.

  As shown in FIG. 3, an opening 39 a for ejecting compressed air into the plastic bottle 1 is formed in the nozzle 39, and this opening 39 a is connected through a communication hole 37 a formed in the pressure head body 37. The pipe 41 is in communication. The pipe 41 is communicated with the port P1 of the first spool type electromagnetic valve EV1 via the first check valve CV1. The first check valve CV1 allows only the flow of compressed air from the first spool type electromagnetic valve EV1 side to the pressure head 35 side, and compresses from the pressure head 35 side to the first spool type electromagnetic valve EV1 side. It is configured to prevent backflow of air. The port P2 of the first spool type electromagnetic valve EV1 is communicated with a communication path 12a in the lower rotary shaft 12 via a pipe 42, and the communication path 12a is communicated with a compressed air source 43 ( (See FIG. 2). The other port P3 of the first spool type electromagnetic valve EV1 is closed by a plug 49. Further, the communication passage 37 a in the pressure head body 37 is connected to the pressure sensor S via the sensor tube 44. The pressure sensors S are installed corresponding to the pressure heads 35, and in the present embodiment, 36 pressure sensors S are installed.

  The communication passage 37a in the pressurizing head 37 is communicated with the port P1 of the second spool type electromagnetic valve EV2 via the pipe 51 and the second check valve CV2. The second check valve CV2 allows only the flow of compressed air from the pressurizing head 35 side to the second spool type solenoid valve EV2 side, and the compressed air from the second spool type solenoid valve EV2 side to the pressurizing head 35. It is configured to prevent the backflow. The port P <b> 2 of the second spool type electromagnetic valve EV <b> 2 is communicated with the communication path 12 a in the lower rotary shaft 12 via the pipe 52, and the communication path 12 a is communicated with the compressed air source 43. The other port P3 of the second spool type solenoid valve EV2 is open to the atmosphere. With this configuration, a predetermined back pressure is applied to the second check valve CV2 through the ports P1 and P2 of the second spool type electromagnetic valve EV2.

FIG. 4 is a longitudinal sectional view showing the structure of the first spool type solenoid valve EV1 and the second spool type solenoid valve EV2. As shown in FIG. 4, a spool 61 is accommodated in the valve body 60 so as to be capable of reciprocating in the axial direction. A pilot valve 62 for operating the spool 61 is disposed adjacent to the valve body 60, and the pilot valve 62 is configured to be operated by an electromagnet 63. Three ports P1, P2, and P3 are formed in the valve body 60.
In the above-described configuration, as shown in FIG. 4A, the spool 61 moves to the left, and the port P1 and the port P2 communicate with each other. Further, as shown in FIG. 4B, the spool 61 moves to the right side, and the port P1 and the port P3 communicate with each other.

FIG. 5 is a longitudinal sectional view showing the structure of the first check valve CV1 and the second check valve CV2. As shown in FIG. 5, a valve seat 71 and a valve body 72 disposed so as to be able to contact with and separate from the valve seat 71 are accommodated in the valve body 70. A packing 73 is attached to the valve body 72. The valve body 72 is urged by a spring 74 so as to be in close contact with the valve seat 71. As shown in FIG. 5A, by applying a back pressure to the valve body 72, the valve body 72 is brought into close contact with the valve seat 71 so that the backflow of compressed air is prevented. Since the spring 74 is interposed, the valve body 72 is in close contact with the valve seat 71 even if there is no back pressure.
In the above-described configuration, as shown in FIG. 5A, when the back pressure is applied to the valve body 72, or even if no back pressure is applied, the fluid from the A side to the B side is applied by the biasing force of the spring 74. Is prevented from flowing back. When the pressure on the B side becomes higher than the back pressure on the A side, the valve body 72 is opened by the pressure of the fluid on the B side, and the fluid flows from the B side to the A side.

Next, the operation of the PET bottle leak inspection apparatus configured as described above will be described.
FIG. 6 is a schematic diagram showing the relationship between the pressure head 35 and the plastic bottle 1 supported by the neck ring star wheel 25. The PET bottle 1 is supplied to the inlet star wheel 2 from the inlet side guide rails 5, 5. The plastic bottle 1 transferred by the inlet star wheel 2 is delivered to the main rotor 10. At this time, the neck bottle 1 a is supported by the neck ring star wheel 25 of the main rotor 10 and the shoulder portion of the plastic bottle 1 is supported by the shoulder pressing star wheel 26. FIG. 6A is a schematic diagram showing this state. In the state shown in FIG. 6A, as the main rotor 10 rotates, the plastic bottle 1 starts to be transported along the pitch circle of the main rotor 10.

  When the PET bottle 1 is transferred to the main rotor 10, the pressure head 35 is lowered by the action of the cam follower 29, and the pressure head main body 37 of the pressure head 35 comes into contact with the mouth 1 m of the PET bottle 1. At this time, as shown in FIG. 6 (b), since the packing 38 is provided on the lower end surface of the pressure head main body 37, the packing 38 is in close contact with the top surface of the mouth portion 1 m of the PET bottle 1. In order to securely seal between the packing 38 and the top surface of the mouth portion 1m of the plastic bottle 1, the pressure head body 37 presses the packing 38 against the mouth portion 1m of the plastic bottle 1 with a predetermined load. However, this load is received by the neck ring star wheel 25 that supports the neck ring 1 a of the plastic bottle 1. The neck ring 1a and the mouth 1m in the plastic bottle 1 are made thicker and stronger than the body for the purpose of attaching a cap or the like. Therefore, even if the pressurizing head main body 37 applies a relatively high load to the mouth portion 1m and the neck ring 1a of the plastic bottle in order to make the sealing function of the packing 38 work sufficiently, the mouth portion 1m and the neck ring 1a of the PET bottle. Will not deform.

  Thus, when the seal between the packing 38 provided on the lower end surface of the pressure head main body 37 and the mouth 1m of the PET bottle 1 is completed, the first spool type electromagnetic valve EV1 is opened, and the pressure head 35 The nozzle 39 and the compressed air source 43 are communicated with each other via the first check valve CV1, and a predetermined amount of compressed air is supplied from the nozzle 39 into the PET bottle 1. At this time, since the first check valve CV1 itself has a regulator function, the rush pressure (rapid increase in pressure) when supplying air to the PET bottle 1 is greatly reduced. The time until it stabilizes increases, and the container internal pressure can be sealed at a higher speed. Moreover, the burden on the pressure sensor S is reduced by reducing the maximum pressure applied to the pressure sensor S used during pressure measurement. In this way, the plastic bottle 1 is filled with compressed air having a predetermined pressure. Then, the first spool type electromagnetic valve EV1 is closed. At this time, the sealing performance of the first spool type electromagnetic valve EV1 is not perfect, but the first spool type electromagnetic valve EV1 is provided between the first spool type electromagnetic valve EV1 and the pressure head 35 from the pressure head 35 side. Since the first check valve CV1 for preventing the reverse flow to the side is installed, the compressed air in the PET bottle 1 does not leak from the first spool type electromagnetic valve EV1. At this time, the port P1 and the port P2 of the second spool type electromagnetic valve EV2 communicate with each other, and back pressure is applied to the second check valve CV2 from the compressed air source 43. Therefore, the second check valve CV2 remains closed, and compressed air does not flow from the pressurizing head 35 side to the second spool type electromagnetic valve EV2 side.

  In this state, the plastic bottle 1 is conveyed along the pitch circle of the main rotor 10, and after a predetermined time during the conveyance, the pressure in the plastic bottle 1 is increased by the pressure sensor S as shown in FIG. Measured. If the pressure in the PET bottle after the lapse of the predetermined time is the same as the initial pressure, it is determined that there is no leak from the PET bottle and there is no defect such as a pinhole in the PET bottle 1.

  After completion of the leak inspection, the second spool type solenoid valve EV2 is operated, the port P3 and the port P1 of the second spool type solenoid valve EV2 are communicated, and the port P1 becomes atmospheric pressure and the second check valve CV2 The back pressure is released, and the compressed air in the PET bottle 1 is exhausted to the outside through the second check valve CV2 and the second spool type electromagnetic valve EV2. Thereafter, the PET bottle 1 is delivered from the main rotor 10 to the outlet star wheel 3, and the normal PET bottle 1 is transferred by the outlet star wheel 3 and transferred to the next process via the outlet side guide rails 6 and 6. On the other hand, the PET bottle 1 determined to be defective is unsupported by the outlet star wheel 3 at the position of the defective product discharge chute 46, and the PET bottle 1 is discharged to the defective product discharge chute 46.

It is a top view which shows the whole structure of the leak inspection apparatus of a PET bottle. It is a figure which shows the detailed structure of a main rotor, and is sectional drawing of a main rotor. It is a schematic diagram which shows the compressed air supply system for supplying compressed air to a pressurization head and a pressurization head. It is a longitudinal cross-sectional view which shows the structure of a 1st spool type solenoid valve and a 2nd spool type solenoid valve. It is a longitudinal cross-sectional view which shows the structure of a 1st check valve and a 2nd check valve. It is a schematic diagram which shows the relationship between a pressurization head and the PET bottle supported by the neck ring star wheel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 PET bottle 1a Neck ring 1m Mouth part 2 Inlet star wheel 3 Outlet star wheel 5,6 Guide rail 7, 8, 9 Guide for star wheels 10 Main rotor 11 Coupling 12,20 Rotating shaft 13 Base plate 14 Support plate 17A, 17B Bearing 18, 22 Bearing housing 19 Support frame 20a Through hole 21 Hollow shaft 25 Neck ring star wheel 26 Shoulder presser star wheel 27, 33 Support 28 Guide bar 29 Cam follower 30 Slide member 32 Fixed plate 34 Cylindrical body 34a Cam surface 35 Pressure head 36 Support rod 37 Pressure head main body 37a Communication path 38 Packing 39 Nozzle 39a Opening 39b Communication hole 41, 42, 51, 52 Piping 43 Compressed air source 44 Sensor tube 46 Defective product Outlet chute 60 Valve body 61 Spool 62 Pilot valve 63 Electromagnet 70 Valve body 71 Valve seat 72 Valve body 73 Packing 74 Spring EV1 First spool type solenoid valve EV2 Second spool type solenoid valve CV1 First check valve CV2 Second check Valve S Pressure sensor

Claims (3)

A main rotor that supports a plurality of plastic bottles and conveys them on a predetermined circumference, a seal member that is installed in the main rotor and that engages with a mouth part of the plastic bottle to seal the mouth part, and gas is sent to the plastic bottle In a PET bottle leak inspection apparatus equipped with a pressure head to be supplied inside,
The pressurizing head is connected to a compressed air source via a first electromagnetic valve to prevent a backflow of compressed air from the pressurizing head side to the first electromagnetic valve side between the pressurizing head and the first electromagnetic valve. A first check valve is provided;
A second electromagnetic valve for connecting the pressurizing head to a second check valve and applying a back pressure to the second check valve for closing the second check valve ;
One port of the second solenoid valve communicates with the atmosphere, and by releasing the back pressure applied to the second check valve, compressed air in the plastic bottle is allowed to flow into the second check valve and the second check valve. (2) A PET bottle leak inspection apparatus which can be exhausted to the outside through a solenoid valve .   2. The PET bottle leak inspection apparatus according to claim 1, wherein the second electromagnetic valve is connected to the compressed air source, and the back pressure is applied to the second check valve. The PET bottle leak inspection apparatus according to claim 1 or 2, wherein the first solenoid valve and the second solenoid valve are spool type solenoid valves.

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