JP5024545B2 - Blow molding machine with pinhole inspection function - Google Patents

Description

  The present invention relates to a blow molding machine with a pinhole inspection function, and more particularly to a blow molding machine with a pinhole inspection function capable of safely and reliably performing pinhole inspection on all blow-molded bottles.

Synthetic resin bottles, particularly PET bottles, have been produced in large quantities in recent years as containers for beverages, foods, and the like because they are lightweight and easy to handle.
In this PET bottle, a primary molded product called a preform is first manufactured by injection molding or the like, then the preform is set in a predetermined mold, and heated to a stretching orientation temperature by a heating means such as a heater, and then heated. So-called biaxial, in which the preform is set in a predetermined mold, a stretching rod is inserted into the preform, and pressurized air is injected, and stretching is performed biaxially by stretching with the stretching rod and pressurized air injection. Obtained by stretch blow molding. In this way, the biaxial stretch blow molding method stretches a heated preform biaxially in a direction perpendicular to the axial direction with a stretching rod and pressurized air, so there are subtle differences in processing force (stretching force) and resin. There is a possibility that a pinhole or the like is generated in the manufactured PET bottle due to mixing of a very small foreign substance into the material. Therefore, it is necessary to inspect whether or not defects such as pinholes have occurred on the PET bottle after blow molding. As an inspection method therefor, for the PET bottle held along the outer periphery of the main rotor, the pressure head is brought into contact with the bottle mouth to fill and seal the inside of the bottle, and the air sealed state Is known for a pinhole inspection method for determining whether or not a pinhole has occurred from the amount of pressure drop of the bottle internal pressure after the predetermined time has elapsed (for example, Patent Document 1 and Patent Document 1) 2).
These pinhole inspection machines are provided separately from the blow molding machine. Therefore, the bottle immediately after blow molding is conveyed from the outlet part of the blow molding machine to the inlet part of the pinhole inspection machine by a conveyance line such as a conveyor. At this time, it is necessary to synchronize the timing when the bottle is put into the pinhole inspection machine and the timing when the pinhole inspection machine takes the bottle. If these timings are not synchronized, an unfavorable situation in terms of production efficiency may occur, such as an empty swing at the pinhole inspection machine or a crowded / congested bottle at the entrance of the pinhole inspection machine. Moreover, well-known mechanisms, such as a timing screw and a gravity wheel, are known as a timing adjustment apparatus which adjusts these timings (for example, refer patent document 3).

JP 2004-205453 A JP 2002-310843 A JP 2004-26435 A

As described above, the timing at which the blow molding machine sends out the bottle and the intake timing at the pinhole inspection machine are generally not synchronized. Therefore, it is necessary to control the timing of bottle insertion by a timing adjusting device such as a timing screw so that the timing of bottle insertion is synchronized with the timing of bottle intake in the pinhole inspection machine.
However, in the case of a timing screw, there is a possibility that the bottle is bitten by the screw portion. Further, when the bottle is transported from the blow molding machine to the pinhole inspection machine, the bottle may fall down during the transportation, and the line may be stopped. These problems can occur in bottles of any shape and strength, regardless of the shape (cross-sectional shape) and strength (thinning) of the bottle in conventional blow molding machines and pinhole inspection machines. Met.
Accordingly, the present invention has been made in view of the problems of the prior art, and provides a blow molding machine with a pinhole inspection function capable of safely and reliably performing pinhole inspection on all blow molded bottles. There is to do.

In order to achieve the above object, a blow molding machine with a pinhole inspection function according to claim 1 is a blow molding machine that stretches and blows a preform biaxially to form a bottle, and inspects the presence or absence of a pinhole in the bottle. pinhole inspection system that is made are integrated,
The blow molding machine and the pinhole inspection system are connected and integrated by a plurality of rotating wheels driven by the same drive .
In the above blow molding machine with a pinhole inspection function, the drive of the pinhole inspection system and the blow molding machine are the same and synchronized, and the pinhole inspection system and the blow molding machine are connected via a conveyor line conveyor, timing adjustment device, etc. So that the bottle can be delivered without being integrated. That is, since the plurality of rotating wheels are driven by the same drive, the rotating wheels are always synchronized and the bottle is conveyed between the rotating wheels. As a result, the blow-molded bottles are sequentially transferred between these synchronized rotating wheels, so that they can be transported to the pinhole inspection section, which is the next process, without going through the conveyor and the timing adjustment device. . As a result, in addition to the fact that the bottle is caught in the threaded part of the timing screw or falls on the conveyance line, no trouble occurs, and all blow-molded bottles can be safely and regardless of the shape and strength of the bottle. The pinhole inspection can be surely performed. Further, by integrating the pinhole inspection system into the blow molding machine, the entire production line including the sterilization / filling system can be saved in space and the equipment can be made compact. Note that the pinhole inspection system can be integrated in the blow molding machine in an integrated form, or can be integrated in the external (additional) form, for example, close to the outlet of the blow molding machine.

The blow molding machine with a pinhole inspection function according to claim 2 , wherein the pinhole inspection system encloses a predetermined amount of gas in the bottle to seal the bottle mouth, and uses the bottle internal pressure immediately after gas sealing as a reference. The amount of pressure drop from the reference internal pressure of the bottle after a predetermined time is measured as the internal pressure, the reference internal pressure exceeds a predetermined first threshold value, and the pressure decrease amount is a predetermined second threshold value. When the pressure does not exceed (when the pressure drop amount is within a predetermined range), the bottle is determined to be a good product without a pinhole.
In the blow molding machine with a pinhole inspection function, the bottle internal pressure immediately after sealing a predetermined amount of gas is measured as a reference internal pressure, and it is determined whether the reference internal pressure exceeds a predetermined first threshold, and the next step After determining whether or not the pressure drop amount exceeds a predetermined second threshold value by measuring the pressure hold and the pressure drop amount, a final non-defective product judgment for the bottle is made. In this way, in addition to setting the threshold value for pressure drop measurement, by setting a threshold value for the reference internal pressure of the bottle pressure immediately after gas sealing, defective bottles with pinholes can be reliably screened out. become.

The blow molding machine with a pinhole inspection function according to claim 3 , wherein the pinhole inspection system encloses a predetermined amount of gas in the bottle to seal the bottle mouth, and the shaft of the bottle after a predetermined time has elapsed. The presence or absence of pinholes in the bottle was determined by measuring the amount of elongation in the direction.
For example, when a predetermined amount of gas is sealed in a lightweight thin-walled bottle and held for a certain period of time, if there is no pinhole in the bottle, the bottle will be elastically deformed in proportion to the increase in bottle internal pressure in the axial direction. On the other hand, if there is a pinhole in the bottle, gas leaks through the pinhole, so that the bottle does not deform in the axial direction or even when it is deformed, its elastic deformation is very small.
Therefore, in the blow molding machine with a pinhole inspection function, the amount of elastic deformation in the axial direction of the bottle when a predetermined amount of gas is sealed in the bottle and held for a certain period of time is measured in the same manner as the pressure drop amount. The presence / absence of holes can be suitably detected.

In the blow molding machine with a pinhole inspection function according to claim 4 , the pinhole inspection system includes a branch line in the middle of the gas supply line or the pressure detection side line of the bottle, and a valve is provided in the branch line. An orifice as a pseudo pinhole was connected.
In the above blow molding machine with a pinhole inspection function, a predetermined amount of gas is introduced into a gas circuit through a normal bottle (without holes), and the gas supply valve is closed, whereby the gas is supplied to the bottle. Form a sealed state. Further, a gas supply line upstream of the bottle or a pressure detection line for detecting the bottle internal pressure is branched, and an orifice as a pseudo pinhole is provided in the branch line via a valve (self-diagnostic valve). Therefore, by opening the valve (self-diagnostic valve) of the branch line, it is possible to form a pseudo leak state as if a pinhole exists in the bottle and gas leaks through the pinhole. become. In other words, the above-mentioned pinhole inspection machine makes it appear that a pseudo pinhole is formed in a normal bottle by connecting a test piece called an orifice to a circuit in which a normal bottle (without holes) is gas-sealed. The detection accuracy of the pinhole inspection machine is confirmed. This eliminates the need to put a test piece in which a pseudo pinhole is perforated in place of a normal bottle in the transport line, and as a result, all the labor and time involved in putting the test piece, including the creation of the test piece, are eliminated. It will be saved. Further, since a metal part called an orifice is used, the phenomenon that the hole diameter increases in proportion to the number of inspections does not occur.

In the blow molding machine with a pinhole inspection function according to claim 5 , the orifice has a variable hole diameter.
In the blow molding machine with a pinhole inspection function, the orifice is configured so that the hole diameter can be changed according to the purpose of inspection, etc., so that various assumed pinholes can be simulated (simulated). become.

In the blow molding machine with a pinhole inspection function according to a sixth aspect of the present invention, the orifice is configured such that a member constituting a part of the flow path of the branch line is provided to be replaceable with respect to the branch line.
In the blow molding machine with a pinhole inspection function, various assumed pinholes can be simulated by exchanging one member forming the flow path with another member having a different hole diameter.

According to the blow molding machine with a pinhole inspection function of the present invention, the drive of the pinhole inspection system and the blow molding machine are the same and synchronized, and the conveyance line conveyor and timing adjustment between the pinhole inspection system and the blow molding machine Since the bottle is integrated in advance so that the bottle can be delivered without using an apparatus or the like, a line trouble occurs in which the bottle is caught in the screw portion of the timing screw or falls on the conveyance line. Disappear. This makes it possible to safely and reliably perform pinhole inspection on all blow-molded bottles regardless of the shape and strength of the bottles. Further, by integrating the pinhole inspection system into the blow molding machine, the entire production line including the sterilization / filling system can be saved in space and the equipment can be made compact. It should be noted that the pinhole inspection system can be integrated into the blow molding machine in a built-in form, or can be integrated in an external (additional) form, for example, close to the outlet of the blow molding machine.
In addition, according to the blow molding machine with a pinhole inspection function of the present invention, pinhole bottles that may have been determined to be non-defective in the conventional pinhole inspection can be surely screened out.
Furthermore, according to the blow molding machine with a pinhole inspection function of the present invention, the inspection accuracy of the inspection machine itself (that the inspection function has not deteriorated) can be appropriately confirmed by the orifice of the self-diagnosis valve. Therefore, the quality of the pinhole inspection is improved. In addition, since a pseudo pinhole is reliably provided in the inspection circuit, all bottles that are put into this inspection machine during the inspection of the inspection machine are out-of-order regardless of the presence or absence of pinholes in the bottle itself. It is judged and rejected from the inspection machine. At this time, if the bottle is determined to be a non-defective product and is not rejected by the inspection machine, it is possible to find out a problem that has occurred in the bottle removal mechanism of the inspection machine.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings.

FIG. 1 is a configuration explanatory view showing a blow molding machine 100 with a pinhole inspection function of the present invention.
This blow molding machine 100 with a pinhole inspection function sets a preform in a predetermined mold and heats it to a temperature at which it can be stretched and oriented by heating means such as a heater, and then preforms a stretch rod that injects high-pressure air. The blow molding unit 110 for producing a bottle as a work-in-process by being inserted into the interior of the bottle and stretched biaxially by a stretching rod and high-pressure air, and the bottle is filled and sealed with air, and the bottle immediately after air filling A pinhole inspection unit 120 that determines whether or not a pinhole has occurred from the internal pressure (reference internal pressure) and the air-sealed state of the bottle for a certain period of time and the amount of decrease in the bottle internal pressure after the lapse of the certain period It comprises. The details of the pinhole inspection unit 120 will be described later with reference to FIGS. 2 and 3.

  Conventionally, bottles as work-in-process immediately after blow molding are transferred to a pinhole inspection apparatus by a conveyance line such as a conveyor, where pinhole inspection is performed. Therefore, a timing adjustment device such as a timing screw is provided in the transport line so that the timing at which the transport line transports the bottle to the entrance of the pinhole inspection machine having an independent drive matches the timing at which the pinhole inspection device takes in the bottle. It was done. However, there has been a problem of line trouble such that the transported bottle is caught in the threaded portion of the timing screw or the bottle falls over the transport line. However, in the blow molding machine 100 with the pinhole inspection function of the present invention, the inspection device (pinhole inspection unit 120) for inspecting the pinhole of the bottle is driven in advance by the same drive to the blow molding machine (blow molding unit 110). Since a plurality of rotating wheels are connected and integrated, a timing adjusting device such as a timing screw and a transport line are not necessary. Therefore, problems such as biting into the timing screw of the conventional bottle and overturning on the transport line do not occur. This makes it possible to safely and reliably perform pinhole inspection on all blow-molded bottles regardless of the shape and strength of the bottles. Further, by integrating the pinhole inspection unit 120 into the blow molding unit 110, the entire production line including the sterilization / filling system can be saved and the equipment can be made compact. The pinhole inspection device may be integrated into the blow molding machine in an integrated form, or may be integrated in the vicinity of the external (additional) configuration, for example, the outlet of the blow molding machine, as in Example 1 described later. Is possible.

FIG. 2 is an explanatory view showing the blow molding part 110 and the pinhole inspection part 120 according to the present invention.
In the blow molding unit 110, a plurality of preforms (for example, 20 pieces) are arranged at equal intervals on the blow wheel 21 via a preform conveyance wheel (not shown) and continuously rotated. The product is supplied to a mold, and the bottle is sequentially molded into a bottle by a stretching rod and blow air in the mold. Then, the formed bottle is taken out from the mold by the gripper of the bottle take-out wheel 22 and transferred to the pinhole inspection unit 120 which is the next process.
In the pinhole inspection unit 120, first, the pinhole inspection wheel 23 receives a bottle from the gripper of the bottle take-out wheel 22 in the previous process by the plurality of grippers 2 that are also arranged at equal intervals on the outer periphery, and pairs with this gripper 2. A predetermined amount of measurement air is supplied to the bottle by an air injector (not shown), and a pinhole inspection is performed on the bottle passing through the pinhole inspection wheel 23. A specific method of pinhole inspection will be described later. Then, the bottle subjected to the pinhole inspection is delivered to the outlet-side transport wheel 24. Therefore, these rotating wheels 21, 22, 23, and 24 exchange bottles in complete synchronization. As shown in the figure, the bottleneck of the object to be inspected by the pinhole inspection machine is not only held by the gripper 2 but also the neck ring of the bottleneck is fitted in the pocket formed at the end of the rotating wheel. It may be a pocket holding.

FIG. 3 is an explanatory diagram showing a main part of the pinhole inspection device of the pinhole inspection unit 120. Although only one pair of the gripper 2 and the air injector 10 is shown in the drawing, in reality, a plurality of pairs of the gripper 2 and the air injector 10 are arranged at equal intervals on the pinhole inspection wheel. Has been.
This pinhole inspection apparatus includes an air injector 10 that supplies air to the bottle 1 and outputs (feedback) the bottle internal pressure, a gripper 2 that stabilizes the posture of the bottle 1 while holding the neck portion of the bottle 1, and an air injection A supply valve 3 for intermittently supplying air to the machine 10, a self-diagnosis valve 4 for forming a pseudo-leak state of the bottle 1, and a pressure detection unit for measuring a pressure drop amount from a reference internal pressure after a predetermined time of the bottle 1 5, an air source 6 that stably supplies air adjusted to a constant pressure, an air supply line 7 that transfers air, a pressure detection line 8 that propagates pressure, a supply valve 3, and a self-diagnosis valve 4. At the same time, based on the signal from the pressure detector 5, when the pressure drop amount exceeds the threshold value, the bottle 1 to be inspected is judged to be an out product and an instruction is given to reject it from the line. It is configured by including a control device 9. Details of the self-diagnosis valve 4 and the pressure detection unit 5 will be described later with reference to FIGS. The “reference internal pressure of the bottle 1” is the internal pressure of the bottle 1 immediately after the supply valve 3 is closed.

  The bottle 1 is a bottle made of a synthetic resin such as a PET bottle. After being blow-molded from a preform, the bottle 1 is conveyed to an inlet (interface) of a pinhole inspection wheel 23 through a bottle take-out wheel 22, where the neck portion is fed by a gripper 2. And is conveyed directly under the air injector 10 in an upright state.

  The supply valve 3 and the self-diagnosis valve 4 are preferably electromagnetic valves from the viewpoint of responsiveness. Further, the supply valve 3 and the self-diagnosis valve 4 are so-called normal close valves that are controlled by the control device 9 and are opened for a predetermined ON time, and the others are kept closed.

  The self-diagnosis valve 4 has an orifice 41 at the outlet. The orifice 41 simulates the pinhole of the bottle 1. Although details will be described later with reference to FIGS. 4 to 8, when the self-diagnosis valve 4 is opened, the air sealed in the bottle 1 flows out of the orifice 41 to the outside, as if a pinhole is formed in the bottle 1. It exists and forms a pseudo leak state as if air leaks from the pinhole. At this time, the control device 9 determines that there is a leak from the pinhole of the bottle 1 based on the pressure drop amount of the bottle 1, drives the gripper 2 and discharges the bottle 1. In this way, by opening the self-diagnosis valve 4, so-called self-diagnosis can be performed in which the inspection accuracy of the pinhole inspection device itself (inspection function is not deteriorated) is confirmed. In addition, the orifice 41 is attached in a replaceable manner so that the pinholes of various bottles that can be assumed can be accurately simulated.

  The orifice 41 may be a variable orifice that includes, for example, a throttle mechanism and whose hole diameter continuously changes. Alternatively, a plurality of members that can be replaced with respect to the branch line may be provided, each having a different hole diameter. Furthermore, the means for varying the orifice diameter is not limited to these, and known means can be used as appropriate.

  The pressure detection unit 5 includes a pressure sensor that measures the internal pressure of the bottle 1 and a differential pressure sensor that measures the amount of pressure drop from the reference internal pressure after a predetermined time has elapsed.

  The air source 6 stably supplies air regulated to a constant pressure in the range of, for example, 20 to 25 [kPa] by a pressure regulating valve or a pressure reducing valve downstream.

  The air supply line 7 starts from the supply valve 3 and branches in two directions through a joint part in the middle thereof, and one end is connected to the supply port 13 and the other end is connected to the self-diagnosis valve 4.

  The pressure detection line 8 connects the pressure port 14 and the pressure detection unit 5. Moreover, the pressure detection line 8 has a joint part connecting the branch line in the middle. Therefore, the self-diagnostic valve 4 is connected to this joint portion in the same manner as the joint portion provided in the air supply line 7 so that the inspection accuracy of the system (the inspection function is not deteriorated) before the pinhole inspection. Confirmation can be performed.

  The control device 9 controls opening and closing of the supply valve 3 and the self-diagnosis valve 4. On the basis of the pressure signal from the pressure detection unit 5, if the amount of pressure drop from the reference internal pressure after a certain time has exceeded a preset threshold value, it is determined that a pinhole exists in the bottle 1, and the gripper 2 is driven and the bottle 1 is discharged. Further, the control device 9 controls the timing of each wheel 21, 22, 23, 24 in FIG. 2 so that the bottles are exchanged appropriately.

  The air injector 10 includes a pressurizing head 11 that abuts against the air tightness at the bottle mouth, a main body 12 having an air supply passage 12a and a pressure detection passage 12b formed therein, The pressure port 13 serving as the introduction port, the pressure port 14 that outputs the internal pressure of the bottle 1, and the spring mechanism 15 that absorbs an impact when the pressure head 11 comes into contact with the bottle mouth portion are configured. Yes.

  The air injector 10 can be moved up and down by an elevating device (not shown). Therefore, when the air is supplied to the bottle 1, the elevating device lowers the pressure head 11 to contact the bottle mouth portion, while exhausting the air from the bottle 1 (releasing the air-sealed state). Raises the pressure head 11 and separates it from the bottle mouth. Further, the pressurizing head 11 may be constituted by an elastic body such as a synthetic rubber in order to secure a sealing property (sealing property) with the bottle mouth portion. Further, the air injector 10 may be provided with an alignment adjusting mechanism that corrects a deviation between the axis of the pressure head 11 and the axis of the bottle 1 together with or instead of the spring mechanism 15.

  FIG. 4 is an explanatory diagram showing the main parts of the self-diagnosis valve 4 and the pressure detector 5.

  The self-diagnosis valve 4 includes an orifice 41 at the outlet. The self-diagnosis valve 4 is normally closed and maintains the sealing performance of the bottle 1 together with the supply valve 3. Further, the orifice 41 is configured such that orifices having different hole diameters can be attached and detached so that pinholes of various bottles can be accurately simulated. Therefore, when the self-diagnosis valve 4 is opened, the air in the bottle 1 flows out through the orifice 41, and as a result, a pseudo leak state is formed as if the air leaks through the pinhole of the bottle 1. Will come to be. Therefore, if the pinhole inspection device itself is normal, it is determined from the amount of pressure drop caused by air outflow that the bottle 1 has a pinhole, and as a result, the bottle 1 is rejected.

  As described above, the self-diagnostic valve 4 eliminates the need to set the test piece in which the pseudo pinhole is drilled in the transport line in place of the bottle 1, and the pseudo leak state in which the pinholes of various bottles are accurately simulated. Self-diagnosis can be performed. Thereby, the confirmation of the inspection accuracy (the inspection function is not deteriorated) of the pinhole inspection unit 120 is appropriately performed, and the quality of the pinhole inspection is improved.

  The pressure detection unit 5 includes a pressure sensor 51 that constantly measures the internal pressure of the bottle 1, a differential pressure sensor 52 that measures a pressure drop amount from a reference internal pressure after the bottle 1 has elapsed for a fixed time, and a differential pressure sensor 52. And a differential pressure valve 53 for bringing the two chambers into communication / non-communication. As will be described later, the opening / closing operation of the differential pressure valve 53 is synchronized with the opening / closing operation of the supply valve 3. When the supply valve 3 is open (ON), the differential pressure valve 53 is simultaneously opened (ON). Thus, when the supply valve 3 is closed (OFF), the differential pressure valve 53 is simultaneously closed (OFF).

  The differential pressure sensor 52 has two chambers: a first chamber 52a that always communicates with the bottle 1 and a second chamber 52b that communicates with the bottle 1 only when the differential pressure valve 53 is ON. Therefore, the pressure in the first chamber 52a constantly monitors the internal pressure of the bottle 1. The second chamber 52b is not in communication with the bottle 1 and the second chamber 52b when the differential pressure valve 53 is OFF (the supply valve 3 is OFF). The pressure in the two chamber 52b indicates the internal pressure of the bottle 1 immediately after the supply valve 3 is turned off. Therefore, the pressure in the second chamber 52b becomes the reference internal pressure when measuring the amount of pressure drop after a fixed time has elapsed in the bottle 1. Therefore, the differential pressure sensor 52 is monitoring (the internal pressure of the bottle 1 immediately after the supply valve 3 is turned off) − (the internal pressure of the bottle 1 in real time) = the pressure drop amount of the bottle 1 after a lapse of time. become.

5 to 8 are explanatory diagrams showing the operation of the self-diagnosis valve 4 and the pressure detection unit 5.
First, as shown in FIG. 5, when the control device 9 opens (ON) the supply valve 3, the differential pressure valve 53 also opens (ON) at the same time, and the bottle 1, the first chamber 52a of the differential pressure sensor 52, and the first Air is supplied to the two chambers 52b. At this time, the bottle is deformed so that the deformable portion such as the body portion bulges outward slightly due to the internal pressure. The inside of the bottle immediately after the introduction of air is in an excessive state in which air molecules collide violently, so that the temperature of the air rises. However, with the passage of time, the inside of the bottle approaches a steady state, and the body portion of the bottle that bulges outward also becomes a normal state. As a result, the internal pressure of the bottle 1 gradually decreases and converges to a constant pressure. At this time, the self-diagnosis valve 4 is closed (OFF).

  As shown in FIG. 6, after a certain ON time of the supply valve 3, that is, after a predetermined amount of air is supplied, the control device 9 turns off the supply valve 3 and the differential pressure valve 53. As a result, the first chamber 52a and the second chamber 52b are not communicated. The indicated value of the pressure sensor 51 at this time becomes a reference internal pressure for pressure drop measurement, and is used in a step of checking whether or not the reference internal pressure exceeds a predetermined threshold and determining the presence or absence of a pinhole. At this time, the pressure in the first chamber 52a and the pressure in the second chamber 52b are equal to each other, and as a result, the differential pressure sensor 52 indicates zero. At this time, the self-diagnosis valve 4 is closed (OFF).

  As shown in FIG. 7, the inside of the bottle 1 is in a steady state after a lapse of a certain time. If the bottle 1 does not have a defect such as a pinhole that impedes the airtightness of the bottle, only a slight pressure drop mainly due to a temperature drop and a barrel expansion occurs. Accordingly, a slight pressure difference corresponding to the pressure drop is generated between the first chamber 52a and the second chamber 52b of the differential pressure sensor 52. At this time, the self-diagnosis valve 4 is closed (OFF).

  As shown in FIG. 8, when the indicated value of the differential pressure sensor 52 (the amount of pressure drop from the reference internal pressure) does not exceed a predetermined threshold value (when no pinhole is present in the bottle 1), the control device 9 The diagnostic valve 4 is opened (ON). As a result, the air in the bottle 1 gradually flows out through the orifice 41, and a pseudo-leak state is formed as if the air is leaking from the pinhole of the bottle 1.

  According to the pinhole inspection unit 120, it is possible to appropriately check the pinhole detection accuracy of the inspection system itself without introducing a test piece in which a pseudo pinhole is drilled instead of the bottle 1 to the transport line. become. This saves all of the labor and time associated with test piece insertion, including test piece creation. Further, since the pseudo leak state of the bottle 1 is formed by the orifice 41 of the self-diagnosis valve 4 provided in the gas supply line of the bottle 1, confirmation of pinhole detection accuracy does not depend on the number of inspections. In addition, since the pseudo-leak state of the bottle 1 can be easily formed by the orifice 41 of the self-diagnosis valve 4, the bottle 1 is not discharged when the self-diagnosis valve 4 is open (ON), for example. It is easy to find defects such as the discharge mechanism. As described above, since the inspection accuracy of the inspection system itself (inspection function is not deteriorated) can be confirmed as appropriate, the quality of the pinhole inspection is improved.

  FIG. 9 is a graph showing an example of determining a non-defective bottle in the pinhole inspection unit 120 according to the present invention.

When the supply valve 3 is opened at time T = t ₀ , air is supplied into the bottle and the internal pressure of the bottle rises rapidly. This corresponds to the state of FIG.
When the bottle 1 is a predetermined amount of air is supplied, the supply valve 3 is closed at time T = t _1. This corresponds to the state of FIG. Here, it is checked whether or not the bottle internal pressure P ₁ (reference internal pressure) immediately after the supply valve 3 is closed exceeds the first threshold value P _th1 . When the bottle internal pressure P ₁ exceeds the first threshold value P _th1 , the bottle 1 is held for a certain time, and the pressure drop amount ΔP from the reference internal pressure is measured.

The pressure drop amount ΔP is obtained from the pressure difference ΔP = P ₁ −P ₂ between the reference internal pressure P ₁ and the bottle internal pressure P ₂ immediately after the elapse of a fixed time, that is, immediately before the pressure head 11 is separated from the bottle mouth. However, the pressure drop amount ΔP is measured by the differential pressure sensor 52 without obtaining the pressure values P ₁ and P ₂ separately. When the measured pressure drop amount ΔP does not exceed the second threshold value ΔP _th2 , the bottle is determined to be a non-defective product.

At time T = t ₂ , the pressure head 11 is separated from the bottle mouth, and the air in the bottle 1 is exhausted to finish the pinhole inspection.

Thus, first, it is checked whether or not the reference internal pressure P ₁ exceeds the first threshold value P _th1 . If it exceeds, the process proceeds to the next pressure drop amount inspection, and it is checked whether or not the pressure drop amount ΔP immediately after closing the supply valve 3 exceeds the second threshold value ΔP _th2 . Only when the pressure drop amount ΔP is within the range of the second threshold value ΔP _th2 , the bottle is determined to be a non-defective product having no pinhole. The first threshold value P _th1 is, for example, 8 [kPa]. The second threshold value ΔP _th2 is 3 [kPa], for example. The reference pressure P ₁ is, for example, 15 to 20 [kPa].

FIG. 10 is a graph showing an example of determining defective bottles in the pinhole inspection unit 120 according to the present invention.
In this bottle, the reference internal pressure P ₁ exceeds the first threshold value P _th1 , but the pressure drop amount ΔP exceeds the second threshold value ΔP _th2 . Therefore, it is considered that this bottle has a pinhole, and this bottle is determined to be defective.

FIG. 11 is a graph showing an example of determining defective bottles in the pinhole inspection unit 120 according to the present invention.
In this bottle, the reference internal pressure P ₁ does not clear the first threshold value P _th1 . Therefore, this bottle is considered to have a pinhole and is determined to be defective. Further, the pressure hold and the pressure drop amount ΔP are not measured, and the pressure head 11 is separated from the bottle mouth portion for a while, and the pinhole inspection is completed.

According to the above pinhole inspection method, the first threshold value P _th1 is provided for the reference internal pressure P ₁ corresponding to the bottle internal pressure immediately after air sealing, and the reference internal pressure P ₁ does not exceed the first threshold value P _th1. The bottle is determined to be defective without measuring the pressure drop amount ΔP. Even if the reference internal pressure P ₁ exceeds the first threshold value P _th1 , if the pressure drop amount ΔP exceeds the second threshold value Δ _th2 , the bottle is determined as a defective product. That is, when the reference internal pressure P ₁ of the bottle 1 immediately after closing the supply valve 3 exceeds the first threshold P _th1 and the pressure drop amount ΔP from the reference internal pressure P ₁ does not exceed the second threshold ΔP _th2. As long as the bottle is determined to be non-defective. Therefore, with the conventional pinhole inspection method that determines the presence or absence of pinholes only by the pressure drop ΔP, pinhole bottles that may be judged as non-defective products can be reliably screened, and pinhole inspection accuracy is improved. improves.

In the actual embodiment, as a pinhole inspection method, the presence or absence of a pinhole is determined based on the pressure immediately after air-sealing the bottle and the pressure drop after a certain period of time. In the case of a bottle with a low tensile strength, it is also possible to determine the presence or absence of a pinhole based on the amount of elongation in the bottle axial direction after sealing the air in the bottle and after a certain time has elapsed. In other words, if there is no pinhole in the bottle, the bottle will show an axial elongation proportional to the increase in internal pressure. However, if there is a pinhole, the bottle will not increase or the bottle will be too small. Even if it shows no elongation in the axial direction, the amount of elongation is very small. Therefore, the axial length L ₀ of the bottle before air sealing and the axial length L of the bottle after a lapse of a certain time are measured, and the elongation amount ΔL = L−L ₀ is calculated, and the air sealing is performed. With respect to the axial elongation rate = ΔL / L ₀ × 100 [%] based on the axial length L ₀ of the previous bottle, the threshold value is set to, for example, 1.0 [%], and if it is more than that, It can be determined that there is no pinhole in the bottle. On the other hand, if it is less than that, it can be determined that there is a pinhole in the bottle. A known position sensor or distance sensor can be used as a means for measuring the amount of elongation in the axial direction of the bottle.

FIG. 12 is a configuration explanatory view showing a blow molding machine 200 with a pinhole inspection function according to the first embodiment.
In this blow molding machine 200 with a pinhole inspection function, a pinhole inspection unit 120 is added near the outlet of the blow molding unit 110, and the blow molding unit and the drive are shared and integrated in a synchronized manner. In addition, conveyance of the blow molded bottle to the pinhole inspection unit 120 is delivered without a conveyor or a timing screw by a gripper rotating in synchronization with the blow molding machine. In this case, similarly to the blow molding machine 100 with the pinhole inspection function, the entire production line including the sterilization / filling system can be saved and the equipment can be made compact.

  Moreover, in the said Example, although air is used as a bottle pinhole test | inspection gas, you may use not only this but inert gas, such as helium and nitrogen, or the mixed gas of these and air.

  The blow molding machine with a pinhole inspection function of the present invention can be suitably applied to blow molding of synthetic resin bottles such as PET bottles.

It is composition explanatory drawing which shows the blow molding machine with a pinhole test | inspection function of this invention. It is explanatory drawing which shows the pinhole test | inspection part which concerns on this invention. It is explanatory drawing which shows the principal part of the pinhole test | inspection apparatus of a pinhole test | inspection part. It is explanatory drawing which shows the principal part of the self-diagnosis valve and pressure detection part which concern on this invention. It is explanatory drawing which shows operation | movement of the self-diagnosis valve and pressure detection part immediately after the supply valve which concerns on this invention is opened. It is explanatory drawing which shows operation | movement of the self-diagnosis valve and pressure detection part immediately after the supply valve which concerns on this invention is closed. It is explanatory drawing which shows operation | movement of the self-diagnosis valve and pressure detection part after the supply valve which concerns on this invention is closed, and fixed time progress. It is explanatory drawing which shows operation | movement of the pressure detection part immediately after the self-diagnosis valve based on this invention is opened. It is a graph which shows an example which determines the good quality bottle in the pinhole test | inspection part which concerns on this invention. It is a graph which shows an example which determines the inferior goods bottle in the pinhole test | inspection part which concerns on this invention. It is a graph which shows an example which determines the inferior goods bottle in the pinhole test | inspection part which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration explanatory view illustrating a blow molding machine with a pinhole inspection function according to a first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bottle 2 Gripper 3 Supply valve 4 Self-diagnosis valve 5 Pressure detection part 6 Air source 7 Air supply line 8 Pressure detection line 9 Control apparatus 10 Air injector 11 Pressurization head 12 Main body 13 Supply port 14 Pressure port 15 Spring mechanism 100, 200 Blow molding machine with pinhole inspection function 110 Blow molding part 120 Pinhole inspection part

Claims (6)

A blow molding machine that stretches and blows a preform biaxially to form a bottle and a pinhole inspection system that inspects the presence or absence of pinholes in the bottle are integrated .
The blow molding machine with a pinhole inspection function, wherein the blow molding machine and the pinhole inspection system are connected and integrated by a plurality of rotating wheels driven by the same drive . The pinhole inspection system encloses a predetermined amount of gas in the bottle to seal the bottle mouth, measures the bottle internal pressure immediately after gas sealing as a reference internal pressure, and the reference of the bottle internal pressure after a predetermined time has elapsed. Only when the pressure drop from the internal pressure is measured and the reference internal pressure exceeds a predetermined first threshold and the pressure drop does not exceed a predetermined second threshold, the bottle is a non-defective product without a pinhole. The blow molding machine with a pinhole inspection function according to claim 1, which is determined as follows. The pinhole inspection system seals the bottle mouth by filling a predetermined amount of gas into the bottle, and measures whether the bottle has a pinhole by measuring the amount of elongation in the axial direction of the bottle after a lapse of a certain time. The blow molding machine with a pinhole test | inspection function of Claim 1 . 3. The pin according to claim 2 , wherein the pinhole inspection system is provided with a branch line in the middle of the gas supply line or pressure detection side line of the bottle, and an orifice as a pseudo pinhole is connected to the branch line via a valve. Blow molding machine with hall inspection function. The blow molding machine with a pinhole inspection function according to claim 4 , wherein the orifice has a variable hole diameter. 6. The blow molding machine with a pinhole inspection function according to claim 4 or 5 , wherein the orifice is configured such that a member forming a part of a flow path of the branch line is replaceable with respect to the branch line.

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