WO1998018572A1

WO1998018572A1 - Apparatus for transporting and inspecting containers and associated method

Info

Publication number: WO1998018572A1
Application number: PCT/US1997/018720
Authority: WO
Inventors: Henry M. Dimmick; Lloyd B. Stivison
Original assignee: Agr International, Inc.
Priority date: 1996-10-30
Filing date: 1997-10-21
Publication date: 1998-05-07

Abstract

An apparatus (10) and method is disclosed for inspecting containers (11) such as blow molded plastic bottles. A wheel assembly contacts the containers (11) to properly position the containers (11) for inspection. The wheel assembly includes at least one star wheel (41, 42) having recesses (40) for receiving the containers. In one embodiment the star wheels (41, 42) are passive, while in another embodiment the star wheels are motor (47) driven. A cooperating idler wheel is used to press the containers (11) into the recesses (40) of the star wheels (41, 42). A magnetic detent assembly (55, 56, 58) may be used to orient the star wheels (41, 42) in the proper angular position to accept oncoming containers. Once a container (11) has been aligned in the desired position, an electronic camera (31) records an image of the container (11) which is then analyzed to determine the presence of any defects. Defective containers (11) may then be automatically removed from the process line.

Description

APPARATUS FOR TRANSPORTING AND INSPECTING CONTAINERS AND ASSOCIATED METHOD

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a system for inspecting containers for defects, and more particularly relates to an inspection system which accurately transports and positions plastic containers for visual inspection.

Background Information

Many types of plastic containers are conventionally made using blow molding equipment for the final stage of forming. The blow molders discharge the formed containers onto conveyors. During the forming of the plastic containers, several types of defects can aπse from the blow molding process, including base folds, off-center gates, white areas and improperly formed feet. Base folds and off- center gates are indicators of problems with the forming process that can result in thin areas in other parts of the container White areas detract from the appearance of the container. Improperly formed feet detract from the appearance and, if severe, can cause handling problems. Ideally, manufacturers want to remove containers wnh these defects before shipping them to their customers.

Visual inspection systems have been developed in order to inspect for these defects. However, conventional devices have inspection system components mounted inside the blow molder, using the existing components of the blow molder to position containers for inspection These prior art systems depend on proper setup of the blow molder so the containers are correctly positioned for visual inspection. While this arrangement is usually satisfactory for base fold inspection, it does not adequately provide for off-center gate inspection because the positioning of the container is not accurate enough. Furthermore, since the inspection system components are inside the blow molder, it is difficult to make necessary mechanical adjustments to them.

U.S. Patent No. 4,691 ,231 to Fitzmorπs et al. discloses a system for visually inspecting the sidewalls of containers on a continuously moving conveyor.

An auger is used to place bottles on a conveyor. Multiple cameras and strobe lights are used to visually inspect the bottles as they move on the conveyor.

U.S. Patent No. 4,751,386 to Gardner discloses an apparatus for detecting off-center containers using multiple light sources and detectors located at various angles around the container.

U.S. Patent No. 4,852,415 to Bogatzki et al. discloses a system for inspecting plastic bottles which rotates the bottles on a turntable during the inspection process. A worm conveyor and wheel assembly is used to deliver the bottles to the turntable, while another worm conveyor and wheel assembly is used to remove the bottles from the turntable.

U.S. Patent No. 4,915,237 to Chang et al. discloses a system for inspecting the sidewalls of bottles which includes belts for rotating the bottles as they are being inspected.

U.S. Patent No. 4,959,538 to Swart discloses an apparatus for optically inspecting the mouths of glass bottles as they travel along a conveyor

U.S. Patent No. 5,059,031 to Hamel et al discloses an apparatus for optically inspecting transparent bottles as they move on a horizontal conveyor A light source is located on one side of the conveyor ard a linear electronic camera is located on the other side of the conveyor. U.S. Patent No. 5,495,330 to Champaneπ et al discloses a system for visually inspecting containers as they pass horizontally along a conveyor

While various container inspection systems have been developed, a need still exists for an inspection system which can accurately position and visually inspect blow molded plastic containers for detects. SUMMARY OF THE INVENTION

The present invention has met the above-described need by providing a system and method capable ot accurately and reproducibly positioning containers for inspection of defects including base defects and off-center gates In a preferred practice of the invention, a visual inspection system is positioned downstream from a blow molder. Containers exiting the blow molder are transported by line pressure on a track or shelf underneath a camera where they are visually inspected. A wheel assembly is used to contact and accurately position the containers under the camera for inspection. The wheel assembly preferably includes at least one star wheel having recesses for receiving the containers, and at least one idler wheel which presses the containers into the recesses. Defective containers which fail the inspection may be rejected by dropping such containers from the track or shelf. An object of the present invention is to provide an oπentmg mechanism located outside of a blow molder to achieve accurate, reproducible positioning of containers for inspection of defects in the base of the containers. Another object of the present invention is to provide an apparatus which correctly positions containers such that a vision system can inspect the containers for other types of defects. A further object of the present invention is to provide a transport and positioning apparatus which can be used with conventional inspection equipment Another object of the present invention is to provide an apparatus capable of rapidly and precisely moving and aligning containers for inspection.

A further object of the present invention is to provide an inspection system which can be positioned adjacent to plastic container blow molding equipment in order to quickly and accurately analyze containers exiting the blow molder for defects.

Another object of the present invention is to provide an apparatus for inspecting containers including means for transporting the containers, means tor inspecting the containers as they are being transported, and means for contacting each container while it is being inspected to position the container with respect to the inspection means.

A further object of the present invention is to provide a method ot inspecting containers for defects including the steps of transporting the containers along a support member such as a track or shelf, contacting the containers with a positioning wheel assembly as they move along the support member to align the containers in an inspection position, and inspecting the containers for defects while aligned in the inspection position These and other objects of the present invention will be more readily understood from the following descπption and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front elevational view of a transport and inspection apparatus in accordance with an embodiment of the present invention.

Fig. 2 is a left side elevational view of the apparatus of Fig. 1. Fig. 3 is a partially schematic top plan view of a positioning wheel and idler wheel arrangement for accurately positioning containers for inspection in accordance with an embodiment of the present invention. Fig. 4 is an end elevational view of a transport and inspection apparatus in accordance with another embodiment of the present invention. Fig. 5 is a partially schematic side view of a magnetic detent mechanism in accordance with an embodiment of the present invention.

Fig. 6 is a partially schematic bottom view of a magnet assembly of the detent mechanism of Fig. 5.

Fig. 7 is a partially schematic side view of another magnetic detent mechanism of the present invention.

Fig. 8 is a side view of a container reject mechanism in accordance with an embodiment of the present invention. Fig. 9 is a partially schematic side view of a rotational sensor in accordance with an embodiment of the present invention.

Fig. 10 is a schematic block diagram illustrating the operation ot an inspection apparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 shows an inspection apparatus 10 in accordance with an embodiment of the present invention. The inspection apparatus 10 transports blow molded plastic containers 1 1 as they exit a blow molder 12 (shown in phantomi Within the blow molder 12, the containers 1 1 are supported by a neck-engaging track 14 and a shelf 15. The containers 1 1 move in a single line in the direction C illustrated most clearly in Figs. 1 and 3 The containers 1 1 typically have a lower cylindπcal portion having diameters of from about 2 to about 6.5 inches. The total height of the containers is usually from about 5 to about 15 inches. While blow molded plastic containers are primarily descπbed herein, other types of containers may also be inspected in accordance with the present invention including glass containers as well as metal and plastic cans.

The inspection apparatus 10 includes a stand 21 shown in Figs. 1 and 2 preferably having adjustable feet 22. The stand 21 includes an upper surface 23 which supports a transfer track 24 by means of support brackets 25 and 26. As the containers 1 1 exit the blow molder 12, they are supported by the neck by the transfer track 24. As shown most clearly in Fig. 4, each container 1 1 includes a beaded neck 13 which πdes on the transfer track 24. While the containers 11 are supported by a transfer track 24 in the embodiments shown in the drawings, other support members may be used in place of, or in addition to, the transfer track 24.

For example, the support member may compπse a shelf upon which the containers 1 1 slide. The use of such a shelf is particularly suitable in process lines where the containers are transported on a conveyor rather than supported by a track.

An electronic camera 31 or other inspection device is preferably positioned above the track 24 for inspecting the containers 1 1 as they pass underneath, as shown in Figs. 1 , 2 and 4. The camera 31 may be attached to the stand 21 by a support bracket 32. The bracket 32 may be made of rectangular extruded aluminum having slots for accepting t-nuts which allow vertical adjustment of the camera 31. Adjustment handles 33 allow for vertical and horizontal positioning of the camera 31 A light source 35 is located under the camera 31 below the containers 1 1 in order to provide illumination for the camera 31 At least the base of the containers should be translucent, and preferably substantially transparent, in order to allow light to pass from the light source 35 through the containers 1 1 to the camera 31. An adjustable bracket assembly 36 permits the light source 35 to be moved vertically and locked into the desired position Guide rails 37 and 38 are provided on opposite sides of the containers 1 1 in order to help provide lateral support for the containers as they travel on the transfer track 24

As shown in Figs. 1-4, as the containers 1 1 are transported along the transfer track 24 or other support member, they come into contact with star wheels 41 and 42 having a plurality of recesses 40 for receiving the containers. The recesses 40 of each star wheel 41 and 42 are substantially vertically aligned The star wheels 41 and 42 are fixedly secured to flanges 43 and 44 which, in turn, are secured to a rotatable shaft 45 A bearing housing 46 mounted on the top 23 ot the stand 21 by means of a horizontally movable base plate 27 facilitates axial rotation of the shaft 45 and star wheels 41 and 42. The star wheels 41 and 42 are preferably made of a relatively rigid material such as stainless steel or rigid plastic. As shown most clearly in Fig. 3, the recesses 40 of the star wheels are preferably of substantially uniform radius having substantially the same diameter as the containers to be inspected. Thus, the recesses 40 are large enough to allow complete insertion of the containers, but are not so large as to permit the containers to move around in the recesses to an undesirable extent.

In one embodiment, the star wheels 41 and 42 are driven by a motor 47, as shown most clearly in Fig. 2. The motor 47 is mounted on the stand 21 by means of a bracket 48 attached to the base plate 27 which can be moved horizontally toward or away from the container 1 1. The motor 47 drives the shaft 45 by means of a belt assembly 49. The bracket 48 may be slotted to allow the motor 47 to be moved horizontally for adjusting drive belt tension. A toothed gearbelt is preferably used to transfer power from the motor 47 to the star wheel shaft 45 in order to prevent slippage. In this embodiment, the motor 47 drives the star wheels 41 and 42 to engage the containers 1 1 and move them along the track 24 in direction C. The use of motor-driven star wheels is particularly suitable for use downstream of blow molders that discharge into an air conveyor, as more fully described hereinafter.

In another embodiment shown in Fig. 4, the star wheels 41 and 42 are passive rather than motor driven. The passive star wheels 41 and 42 may be rotated to a preferred angular orientation which facilitates entry of the containers 1 1 into the recesses 40 of the star wheels. Positioning of the star wheels 41 and 42 may be achieved by a magnetic detent mechanism such as that shown in Fig. 4. A rotatable permanent magnet 55 is connected to the shaft 45. A stationary permanent magnet 56 is located adjacent the rotatable magnet 55 in such a manner that the poles of the magnets attract each other when the star wheels 41 and 42 are in a desired angular orientation, and repel each other when the star wheels are not in a desired position.

Figs. 5 and 6 illustrate one type of magnetic detent mechanism suitable for use in accordance with the present invention. A stationary permanent magnet 56 is secured to a stationary shaft 58, while a rotatable magnet 55 is connected to the star wheel shaft 45. Each of the magnets 55 and 56 comprises a permanent, multi-poled magnet made of ceramic or other suitable material of sufficient magnetic field strength. As the star wheel shaft 45 rotates to a stop, the magnetic poles, shown in Fig. 6, become aligned with the north poles of the rotatable magnet 55 adjacent to the south poles of the stationary magnet 56. This alignment causes the star wheel shaft 45, and hence the star wheels 41 and 42, to stop at the desired angular position. When the magnetic poles are misaligned, the net magnetic force is repulsive and tends to force the star wheel shaft 45 to rotate into the correct alignment. While only four magnetic poles are shown in Fig. 6, the number of magnetic poles may be varied depending on the number of star wheel pockets. It is preferred to keep the air gap between the magnets 55 and 56 to a minimum in order to increase magnetic force.

Another type of magnetic detent mechanism suitable for use in accordance with the present invention is shown in Fig. 7. In this embodiment, the rotatable magnet 55 comprises a plurality of dipole magnetic disks mounted around the circumference of the star wheel shaft 45. The disks of the rotatable magnet 55 may comprise any suitable material such as a neodymium ferrous alloy. The stationary magnet assembly 56 includes two dipole rectangular magnets mounted on the stationary shaft 58 on opposite sides of the rotatable magnet 55. The dipole disks of the rotatable magnet assembly 55 are mounted on the star wheel shaft 45 such that the two north poles N and the two south poles S face away from the shaft as shown. The rectangular magnets of the stationary magnet assembly 56 are arranged with a north pole N of one of the rectangular magnets facing the shaft 45 and the south pole S of the other rectangular magnet facing the rotating shaft 45. The number of dipole disk magnets of the rotatable magnet assembly 55 may be varied depending on the number of pockets contained in the star wheels. By adjusting the angular position of the rectangular magnets of the stationary assembly 57, the angular stopping position and the star wheels can be controlled.

Referring to Figs. 1 -4, an idler wheel 51 is positioned on the opposite side of the containers 1 1 from the star wheels 41 and 42. The idler wheel 51 is rotatably mounted on the stand 21 by an adjustable bracket 52 mounted on a plate 53 having a slotted opening for vertical adjustment of the bracket 52. An adjustment handle 54, shown most clearly in Fig. 2, permits the idler wheel 51 to be moved vertically to the desired position. Another adjustment handle 59, shown most clearly in Fig. 4, permits the idler wheel to be horizontally positioned in the desired location in intimate contact with the containers 1 1. Where multiple star wheels 41 , 42 are used, the vertical height of the idler wheel 51 is preferably between that of the star wheels, most preferably midway between the star wheels.

The idler wheel 51 presses against the containers 1 1 to force them into the recesses of the star wheels 41 and 42. The idler wheel 51 is preferably passive rather than being motor driven. As shown most clearly in Fig. 3, the idler wheel 51 is preferably deformable in order to provide resiliency as it contacts the containers 1 1. Resiliency is provided by open pockets in the idler wheel 51 which allow the outside circumference of the wheel to be deformed radially inward upon contact with the containers 1 1. In addition, the idler wheel 51 is preferably made of a resilient material such as rubber, urethane or foam in order to provide increased deformabi ty. The number and spacing of the star 41 , 42 and idler 51 wheels may be adjusted depending on the size of the containers to be inspected. The idler wheel 51 is preferably spaced in relation to the star wheels 41 , 42 a distance slightly less than the diameter of the containers 1 1 to be inspected. As shown in Fig. 3, the outer circumferential surface of the idler wheel 51 is spaced a horizontal distance away from the star wheels 41 and 42 such that when a recess 40 is aligned with the idler wheel 51 the innermost surface of the recess is slightly closer to the idler wheel 51 than the diameter D of the containers 1 1 to be inspected. This provides a reduced or narrowed path between the outer circumference of the idler wheel 51 and the innermost surface of the aligned recess defining a distance that is preferably from about 0. 1 to about 10 percent smaller than the diameter D of the containers 1 1 , and more preferably from about 1 to about 2 percent smaller. In this manner, as the containers travel in the direction C tangentially between the idler and star wheels, the relative locations of the idler wheel 51 and star wheels 41 , 42 causes the idler wheel 51 to deform radially inward upon contact with each container 1 1. Each container 1 1 is thus pressed by the idler wheel 51 tightly into the recesses 40. This action ensures that the containers 1 1 are accurately positioned under the camera 31 , as shown most clearly in Fig. 4 An encoder assembly 57 as shown in Fig. 4 may be used to indicate the angular orientation of the star wheels 41 and 42. The encoder assembly 57 may be mounted on the same base plate 27 as the bearing housing 46, as shown in Fig. 2. The encoder may be used with either motor-driven or passive star wheels. The encoder assembly 57 tracks the amount of movement of the star wheels 41 and

42 from the time that a position sensor, described more fully below, sends a signal to the camera 31 to record an image until the time that the image is actually obtained. If the camera 31 has a lag time, the image may not be recorded at the precise time needed. Since the star wheels 41 and 42 continuously rotate, the encoder 57 measures the amount of travel of the star wheel shaft with very high resolution on the order of 0.010 inch.

The inspection apparatus 10 may include a reject mechanism 61 as shown in Figs. 1 and 2 for removing defective containers. The reject mechanism 61 includes rams 62 contacting a portion of the transfer track 24 on both sides of the containers 1 1. Actuators 63 such as hydraulic or pneumatic cylinders or solenoids are used to press the rams 62 against a movable portion of the transfer track 24 to deflect the track and cause a defective container 1 1 to drop therefrom. For example, a portion of the transfer track 24 may be hinged such that the portion rotates outward to cause a given container to drop from the track 24. A microprocessor, described more fully below, receives a signal from the camera 31 and determines if a defect is present in the image. If a defect exists, the microprocessor tracks the container to the reject mechanism 61 and sends a signal to the mechanism to drop the defective container from the track 24. Alternatively, where a shelf is used as a support member in place of the track 24, the shelf may likewise include a section that may be deflected to allow a defective container to drop or otherwise be removed from the shelf.

Non-defective containers are conveyed from the transfer track 24 of the inspection apparatus 10 onto another conveying system 71 for further processing. A conveyor belt 72 and guide rails 73 may be used to support and guide the containers 1 1 as they travel.

Fig. 8 illustrates a preferred reject mechanism 61 in accordance with the present invention. Air pressure is provided to the actuator cylinders 63 by means of air supply lines 64. The rams 62 are connected by means of linkages h to rotatable gates 66. The gates 66 engage underneath the neck flange 13 of the container 1 1 and are pivotally mounted on the support member 67 by means of pivot pins 68. When a container is to be rejected, air pressure or other fluid pressure is applied to the cylinders 63 to thereby pull up on the rams 62 and to rotate the gates 66 outward from engagement with the neck flange 13. Since the neck flange 13 is no longer supported, the container 1 1 falls downward. To assist moving the container 11 downward as quickly as possible, a blast of air may be supplied by a reject nozzle 69. The nozzle 69 is attached to the support member 67 by a bracket 75. Pressurized air is supplied to the nozzle 69 from any suitable source. An adjustment screw 76 permits the nozzle 69 to be adjusted to the desired vertical position above the container 1 1.

In accordance with one embodiment of the present invention, alignment and inspection of the containers 1 1 may be achieved by the use of passive star and idler wheels. In this embodiment, line pressure of the passing containers 11 causes the star wheels 41 and 42 to rotate. The line pressure on the containers entering the inspection apparatus 10 may be provided by a motor driven star wheel or other similar mechanism inside the blow molder 12. Such mechanisms space and transfer the containers to the inspection apparatus 10. As a container 1 1 leaves the discharge area of the blow molder 12, the track 24 supports it under its neck flange 13, as shown most clearly in Figs. 2 and 4. Under line, pressure from the blow molder 12, the containers move onto the transfer track 24 where they then enter the recesses of the star wheels 41 and 42. Alternatively, in process lines where the containers 1 1 are transported by conveyors instead of tracks, a take off mechanism may be used to remove the containers from the conveyor for inspection. For example, opposing belts may be used to engage the sides of the containers to transfer the containers from the conveyor to a support shelf. The star wheels 41 and 42 then contact the containers for inspection as they slide along the shelf. After inspection, the containers may be gripped by another pair of opposing belts for transfer from the shelf back to the conveyor line. In many applications, the angular orientation of the star wheels 41 and 42 will not interfere with containers entering the star wheel recesses. Thus, if the recesses of the star wheels are slightly out of position, a container will push the star wheels around slightly until it can enter the recesses. However, in some applications, certain types of containers may not enter the recesses as easily as others. In this case, the magnetic orientor assembly 55 and 56 can be used to ensure that the star wheels 41 and 42 are stopped in the correct angular position to receive a container. The rotatable and stationary magnets 55 and 56 provide magnetic detents which stop the star wheels in one of several correct positions, such that the wheels are ready to receive the next container.

As a container 1 1 pushes the star wheels 41 and 42 around, it comes into contact with the idler wheel 51. The idler wheel 51 deforms slightly as the container is cradled between it and the star wheels 41 and 42. By pressing the containers into the recesses of the star wheels, the containers are accurately positioned for inspection. The guide rails 37 and 38 also assist in keeping the containers 1 1 stable and providing proper lateral support as they move through the inspection area. The number of guide rails used may be varied.

In the preferred embodiment, the containers 1 1 move continuously underneath the inspection station with no indexing. Thus, in the preferred embodiment, the containers do not pause or dwell under the camera 31. The containers 1 1 may travel at a rate of up to about 180 feet per minute or more, typically at a rate of from about 50 to about 125 feet per minute.

In accordance with the present invention, a rotational sensor schematically shown in Fig. 9 may be used to determine when a container is in proper position for inspection. A photoelectric sensor 80 projects a beam of light 81 toward a reflector 82. When a lobe of the star wheel 41 passes between the sensor 80 and the reflector 82, it blocks the beam of light 81. The sensor 80 is positioned such that this blockage occurs when a pocket of the star wheel 41 is in the correct position for an image to be recorded by the camera 31. The rotational sensor 80 is thus used to signal when a pocket of the star wheel 40 is in the correct position. The camera 31 will be triggered to record an image whether or not there is actually a container in the pocket of the star wheel. Preferably, an image analysis algorithm is used to determine whether a container is actually present in the pocket of the star wheel. The rotational sensor 80 is preferably mounted on an adjustable support member (not shown) to allow the sensor to be located in the desired position. Data from the rotational sensor 80 may be fed to a microprocessor 70, schematically shown m Fig. 10, which sends a signal to the electronic camera 31 in order to electronically record each container when it is aligned underneath the camera 31. The electronic camera 31 is preferably positioned as shown in Fig. 4 such that it can provide an image of the base of each container in order to inspect for defects such as base folds. In addition, the camera 31 may inspect for off-center gate, which indicates that a part of the container may be thinner than desired.

After being inspected, containers that do not have defects continue along the transfer track 24 onto the support track 71 Containers having defects are preferably removed from the transfer track 24 by the reject mechanism 61. When the vision inspection system such as the camera 31 finds a defect, it provides a reject signal to the microprocessor 70, shown schematically in Fig. 5, which then sends a signal to actuate the reject mechanism 61. When the reject mechanism 61 is actuated, a portion of the transfer track 24 may pivot outward, causing the defective container to drop through an opening in the stand 21. In one embodiment, several photosensors (not shown) may be positioned in a linear array between the camera 31 and the reject mechanism 61 in order to track the movement of each container from the star wheels 41 and 42 to the reject portion of the transfer track 24 Alternatively, the encoder 57 may be used to track the movement ot the containers by recording the rotational movement of the star wheels 41 and 42 Data from the array of sensors may be fed to a microprocessor to actuate the reject mechanism 61 , ensuπng that only the defective container is removed.

In some applications it may be desirable to use motor-driven star wheels as shown in Fig. 2. For example, where the blow molder 12 discharges into an air conveyor, there may be essentially no line pressure on the containers as they exit the molder. In this case, the motor 47 rotates the star wheels 41 and 42 in order to move the containers 1 1 along the transfer track 24 or shelf. The motor 47 may be controlled such that it only rotates when a container is present The speed of the motor 47 may be controlled by a closed-loop system such that the rotational speed of the star wheels matches the linear speed of the containers. In this embodiment, a sensor arrangement could be used to ensure that the star wheels always stop in the correct position to receive the next container Fig. 10 schematically illustrates a microprocessor control system for use in accordance with the present invention. A microprocessor 70 receives a signal from the rotational sensor 80, which indicates the rotational orientation of star wheels such as those shown in Fig 1. When it is determined that a recess of the star wheels is aligned vertically below the electronic camera, the microprocessor 70 provides a signal to the camera 31 to electronically record an image of a container positioned in the recess directly below the camera. This electronic image is fed to the microprocessor 70 where the image is analyzed for defects in accordance with known methods. The microprocessor 70 is preferably a personal computer incorporating a frame grabber which uses image analyzing software to evaluate pixels of the image to detect light levels and transitions corresponding to defects. Reject parameters are preferably programmable by an operator to adjust the defect sensitivity of the system. The microprocessor 70 may also generate processing data in the form of reports and/or video displays If a defect is detected by the microprocessor 70, it then sends a signal to the reject mechanism 61 which removes the defective container from the process line Where motorized star wheels are used, they may be controlled by a separate motor speed controller with closed loop teedback control of the motor speed Alternatively, the motor speed may be controlled by a programmable logic controller The control of star wheel motor speed does not necessarily need to be controlled by the microprocessor 70

The following example is intended to illustrate various teatures of the present invention and is not intended to limit the scope thereof

EXAMPLE A transport and inspection apparatus similar to that shown in Fig 1 is positioned downstream from a conventional blow molder such as that sold bv Sidel Corp. as model SB02424 In accordance with conventional practice, plastic preforms are fed into the blow molder by a conveyor Lamps inside the blow molder heat the preforms to a temperature at which the plastic will flow under a mechanical force The preform is then placed into a mold having the final shape of the container Air is applied to the preform, forcing the cylindπcal portion downward such that it takes the shape of the mold The blow molded containers have an upper neck portion and a lower generally cylindrical portion as shown in Fig. 4, and are suitable for holding beverages and other liquids. The height of each container is 9 inches, while the outside diameter of the cylindπcal portion of each container is 3 inches. The containers have a capacity of 500 milliliters, and are made of PET plastic. The containers exit the blow molder under line pressure which pushes the containers against each other and causes them to move at a rate of

100 ft./min. along a track which supports their necks. The line pressure causes each container to move into vertically aligned recesses of passive star wheels similar to those shown in Figs. 1 and 3 having outer diameters of 14 inches. The recesses have a uniform radius of 1.5 inches and extend from the outer circumference of the star wheel radically inward a distance of 1.5 inches. As each container enters a recess, it pushes the star wheel around and continues to travel along the support track where it contacts an idler wheel having a diameter of 4 inches. The axis of rotation of the idler wheel is 17 15/32 inches away from the axis of rotation of the star wheels. The idler wheel and star wheels thus define a pathway which is slightly narrower than the diameter of the containers. The idler wheel deforms radially inward a distance of 1/32 inch and forces the container tightly into the recesses. At the point where the container is directly aligned between the rotational axis of the star wheels and the rotational axis of the idler wheel, it is in position for inspection. At this instant, a lobe of the star wheel passes between a photoelectric rotational sensor and its accompanying reflector blocking its beam of light This provides a signal to the microprocessor which indicates that the star wheels are in proper angular oπentation for inspection. The microprocessor then sends a signal to an electronic camera to electronically record an image of the container located directly below it. An encoder attached to the star wheels in a manner shown in Fig. 4 provides a signal to the microprocessor which indicates the amount ot star wheel movement from the time the rotational sensor signaled to record the image until the time the actual image is recorded. This image is then analyzed by the microprocessor to determine whether the container has a base fold or an off-center gate. Non-defective containers continue to move on the support track under line pressure and are transferred onto a track and conveyor assembly similar to that shown in Fig. 1 for further processing When the microprocessor determines the presence of a defective container, it sends a signal to a reject mechanism which pivots a portion of the support track in order to drop the defective container from the process line.

While preferred embodiments have been described herein, it is to be understood that various changes, adaptations and modifications may be made by those skilled in the art. For example, a single star wheel or more than two star wheels may be used. In addition, multiple idler wheels may be used. The star wheels may also be replaced with a cateφillar-type orientor. This arrangement may include a cateφillar mechanism on both sides of the containers, or a cateφillar mechanism on one side and a passive idler wheel on the other side. Such a cateφillar mechanism may comprise a motor driven conveyor section, the surface of which has recesses to receive the containers. Furthermore, other types of visual inspection arrangements could be used to inspect various parts of the containers. For example, cameras could be placed to inspect the sealing surface of the container finish, or for visual measurements of finish dimensions. Thus, it will be evident to those skilled in the art that numerous variations of the details described herein may be made without departing from the invention as set forth in the appended claims.

Claims

CLAIMS:

1. Apparatus for inspection of containers compπsing: transfer means for transporting the containers to be inspected; inspection means for inspecting the containers as they are transported by the transfer means; and positioning means for contacting each container as it is being inspected to align the container with the inspection means.

2. The apparatus of Claim 1 , wherein the positioning means compπses at least one star wheel having recesses for receiving the containers

3. The apparatus of Claim 2, wherein the containers have a substantially cylindπcal portion and the recesses have a substantially uniform radius which substantially conforms to the cylindπcal portion of the containers.

4. The apparatus of Claim 2, wherein the positioning means compπses at least one idler wheel located opposite the at least one star wheel, whereby the at least one idler wheel forces each container into a recess of the at least one star wheel.

5. The apparatus of Claim 4, wherein the positioning means compπses at least two of the star wheels spaced one vertically above the other with the recesses of the star wheels aligned in substantially the same angular orientation

6 The apparatus of Claim 5, wherein the at least one idler wheel is located at a vertical height between the at least two star wheels.

7 The apparatus of Claim 4, wherein the idler wheel is deformable

8 The apparatus of Claim 7, wherein the idler wheel includes deformable open pockets and is made ot a resilient mateπal.

9. The apparatus of Claim 2, wherein the at least one star wheel is motor driven.

10. The apparatus of Claim 2, wherein the at least one star wheel is passive.

1 1. The apparatus of Claim 10, wherein the apparatus compπses oπenting means for rotating the at least one star wheel to at least one selected angular position.

12. The apparatus of Claim 1 1 , wherein the oπenting means compπses a rotatable magnet mounted for rotation with the at least one star wheel and a stationary magnet mounted adjacent the rotatable magnet, the magnets having poles aligned for attraction when the at least one star wheel is in the at least one selected angular position.

13. The apparatus of Claim 2, further compπsing position indicating means for indicating when a container is in position for inspection by the inspection means.

14. The apparatus of Claim 13, wherein the position indicating means includes rotational sensor means for indicating when a recess of the at least one star wheel has been rotated into alignment with the inspection means.

15. The apparatus of Claim 1 , wherein the transfer means transports the containers in a substantially horizontal direction.

16. The apparatus of Claim 15, wherein the transfer means comprises track means for supporting each container under a neck flange of the container.

17. The apparatus of Claim 16, wherein the transfer means further compπses at least one guide rail for guiding the containers as they are transported by the transfer means.

18. The apparatus of Claim 17, wherein the guide rails are positioned on opposite sides of the containers.

19. The apparatus of Claim 15, wherein the inspection means compπses means for visually inspecting the containers.

20. The apparatus of Claim 19, wherein the visual inspection means is located vertically above the transfer means.

21. The apparatus of Claim 20, wherein the visual inspection means compπses an electronic camera.

22. The apparatus of Claim 21 , wherein the visual inspection means further compπses a light source located vertically below the transfer means.

23. The apparatus of Claim 1 , wherein the containers are blow molded plastic containers.

24. The apparatus of Claim 23, wherein the transfer means is located downstream from a blow molder.

25. The apparatus of Claim 24, wherein the transfer means includes a substantially horizontal track for supporting a neck flange of each container as each container exits the blow molder.

26. The apparatus of Claim 25, wherein the transfer means further includes reject means for removing defective containers from the track after the containers have been inspected by the inspection means.

27. A method of inspecting containers for defects, the method compπsing: transporting the containers to be inspected along a support member; contacting the containers with a positioning wheel assembly as they move along the support member to align the containers in an inspection position; and inspecting the containers for defects while aligned in the inspection position.

28. The method of Claim 27, further comprising providing the positioning wheel assembly with at least one star wheel having recesses for receiving the containers

29 The method of Claim 28, further comprising providing the recesses with a substantially uniform radius substantially conforming to a cylindrical portion of the containers

30. The method of Claim 28, further compπsing providing the positioning wheel assembly with at least one idler wheel located opposite the at least one star wheel to force each container into a recess of the at least one star wheel

31. The method of Claim 30, further compnsing providing the positioning wheel assembly with at least two of the star wheels spaced vertically one above the other with the recesses of the star wheels aligned in substantially the same angular orientation.

32. The method of Claim 30, wherein the idler wheel is resiliency deformable.

33. The method of Claim 28, further comprising dπving the at least one star wheel.

34. The method of Claim 28, further compπsing providing oπenting means for rotating the at least one star wheel to at least one selected angular position

35. The method of Claim 27, further compπsing inspecting the containers for defects with an electronic camera.

36. The method of Claim 35, wherein the electronic camera is located vertically above the containers.

37 The method of Claim 36, further comprising providing a light source vertically below the containers.

38. The method of Claim 27, further comprising sensing the rotational position of the positioning wheel assembly.

39 The method of Claim 27, wherein the support member compπses a track

40. The method of Claim 27, wherein the containers are blow molded plastic containers.

41. The method of Claim 40, further compπsing discharging the containers onto the support member from a blow molder.

42. The method of Claim 41 , wherein the containers exit the blow molder under line pressure and the positioning wheel assembly is passive

43 The method of Claim 41 , wherein the containers exit the blow molder under substantially no line pressure and the positioning wheel assemblv is motor dπven

44 The method of Claim 27, further comprising rejecting a defective container from the support member after the container has been inspected