Test apparatus for checking container products

A test apparatus checks containers (13) of plastic and produced using the blow-moulding, filling and sealing methods. The containers are filled with fluid that can contain particulate contamination deposited on the container wall when the container (13) is still and floating freely in the fluid when the container (13) is moving and/or changing position owing to the movement. The contamination can be detected by a sensor (37). By a vibration device (23), the container (13) can be oscillated at a prespecifiable excitation frequency such that the particulate contamination (47) in the fluid can be detected.

FIELD OF THE INVENTION

The invention relates to a test apparatus for checking container products that are preferably composed of plastic materials and are produced using the blow-molding, filling and sealing method. The container products are filled with fluid that, for production-related reasons, can contain particulate contamination. The contamination is deposited on the container wall when the container is still and appears floating freely in the fluid when the container is moving and/or at least changes its position. In this way, the contamination can be detected by a sensor.

BACKGROUND OF THE INVENTION

Container products produced according to the blow-molding, filling and sealing method, which is also referred to as BFS method in technical parlance, are produced, particularly in ampoule form, in large quantities, for example using the bottelpack® method known from prior art. Such ampoules are usually used for receiving and dispensing fluids for therapeutic or cosmetic purposes. In particular in the case of ampoules, which are intended for injection purposes, a basic prerequisite for use is, in addition to sterility, the purity of the filling material, i.e., the absence of any dirt particles. With regards to product safety, checking each container product with regard to the integrity of the filling material before distribution is essential. Owing to the large quantities in which ampoule-type or bottle-type container products are produced using the BFS method and the resulting short cycle times in the production process, manual checks of each container are hardly feasible. Automation of the checking process by a test apparatus is unavoidable.

As state of the art in this respect, document DE 103 39 473 A1 discloses an apparatus of the type mentioned at the outset, in which the sensor device has several cameras and a pivot mirror for the detection of particulate contamination. The pivot mirror reflects onto respective cameras light rays produced by lamps when they have passed out of a container. The known apparatus has several disadvantages. To capture each of the containers moved through a test section while standing upright on a circuitous track at high production speeds using a camera, a large number of cameras and a corresponding number of lamps are required. The radiation of the lamps is to be reflected during the circular motion on respective assigned cameras.

In addition to the significant constructional effort, this design requires a corresponding control effort for the pivot motions of the mirror. To permit adequate testing reliability, the mirror pivot motions must be realized in a particularly precisely synchronized manner. In addition, the reliability of the test results is not entirely satisfactory because, during the upright motion of the containers on the circuitous track, significant accumulation of particulate contamination is on the base of the container. To remedy this problem, the known apparatus provides a turntable for each container to be tested. The container is set in rotation about its vertical axis to stir up the fluid. In spite of the significant constructive effort involved, the testing reliability still leaves a lot to be desired. One particular disadvantage is that the known apparatus for testing containers, which are economically produced using the BFS method in the form of container cards based on multiple adjacent and connected containers, cannot be used because a rotation of each container about its vertical axis is not possible.

SUMMARY OF THE INVENTION

The invention addresses the problem of providing a test apparatus that allows economical testing with improved reliability of results.

According to the invention, this object is basically achieved by a test apparatus having, as a significant feature of the invention, a vibration device. The container can be oscillated at a pre-specifiable excitation frequency in such a way that the particulate contamination in the fluid can be detected. As testing has shown, the oscillation motion of the containers leads to free motion of particles with different motion patterns depending on the type of particle. Compared with the known rotational motion of the containers, increased reliability of detection can be achieved, with improved differentiation of the particle types. In particular, high reliability of detection can be achieved when the excitation frequency is appropriately adapted to the fluid properties. The frequency is in the low frequency range of up to 2 kHz for high-viscosity fluids or in the upper range of 2 to 10 kHz for low-viscosity, thin fluids.

Particularly advantageously, the vibration plane of the oscillating motion extends along the longitudinal direction, preferably along the midplane of the container. The container can be a component of a multiple container arrangement connected like cards.

In preferred exemplary embodiments, the excitation frequency is selected such that, depending on the viscosity of the fluid contents of the container, larger air bubbles remain stationary in the fluid. The particulate contamination to be detected moves in the fluid. Erroneous results due to a detection of air bubbles can then be avoided. The excitation frequency can advantageously also be set such that the formation of air bubbles is avoided or minimized.

The sensor device can have at least one emitter, which emits rays such as visible light, infrared light, laser light or X-rays. The rays pass through at least the container wall and the fluid and, after striking a detector disposed on the opposite side, generate a measurement signal that can be evaluated by an evaluation device. The radiation type can be appropriately chosen depending on the transparency or opacity of the container wall. For example, X-rays can be used in the case of an opaque container wall.

In particularly advantageous exemplary embodiments, preferably after the container filled with fluid has been oscillated, a detector formed as a camera/recording device takes several pictures of the particulate contamination moving or being moved in the fluid. The evaluation unit compares image sections captured once without particulate contamination and once with particulate contamination. The comparison of several pictures permits a high level of reliability of the results. The pictures of the picture series can be taken at short time intervals, for example, within one second, i.e., the apparatus according to the invention is suitable for high production speeds.

In particularly advantageous exemplary embodiments, a handling device is provided. The handling device moves the container to be tested to a horizontal position in a station in which the detector is disposed below and the emitter is disposed above the container, and to a second station in which the detector is disposed above and the emitter is disposed below the container. In the first station, the detector, in particular in the form of a camera, can be focused on the lower side wall of the container from below, while in the second station the camera is focused on the fluid surface from above. In this way, air bubbles, which could be wrongly identified as particulate contamination, can be reliably detected because they are situated on the upper side wall in the horizontal position and can be differentiated from other actual dirt particles that are mobile. Also, moved particles and particles, which tend to adhere to side walls, such as plastic particles, can be differentiated from particles that float freely in the fluid.

The detection of dirt particles relies on the identification of free motion of particulate materials in the container, which motion is at a standstill following the oscillating motion. Immediately after the oscillation stops, the fluid is, however, still in motion and produces mobile shadows in pictures, which can lead to an incorrect test result. In view of this problem, in advantageous exemplary embodiments of the invention, the handling device hold the container for a pre-specifiable rest period in a rest position until the fluid in the container has largely settled.

The handling device can be equipped with handling aids disposed in the manner of a carousel. By the handling device, the container products can be loaded onto and unloaded from the production line. The test apparatus can then form a component of the production line of the container products produced using the BFS method.

For the evaluation of the measurement signals, the evaluation unit can use computerized image processing methods, which are commonly encountered in the prior art, such as grey value transformation, point operation and/or blending methods and which are based on known algorithms.

Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the drawings, discloses a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

InFIG. 1, a central handling carousel1can be moved by grippers3,5,7and9counter-clockwise. By a belt conveyer11, ampoules13to be tested (FIG. 2) are supplied standing upright as a container belt to the gripper3situated in a loading station30. Gripper3is situated at the start of the test section formed by the handling carousel1. Directly in front of the gripper3, a separator15of the container belt separates container cards having, in the present case, four ampoules13.

The grippers3,5,7,9each have a support unit17, one of which is depicted inFIG. 2in a position removed from the carousel1and next to the belt conveyer11. As can be seen fromFIG. 2, each support unit17has four ampoule receptacles19, in each of which a container card14having four ampoules13can be received. The ampoules13are situated with their closing part, which has a rotary knob or rotatable closure as shown inFIG. 2, inside the receptacle19, while the ampoule body containing the fluid is exposed, as can be seen in the case of the gripper3inFIG. 2. AsFIG. 2also shows, the position of the gripper3is such that the ampoules13are vertical and standing upright, i.e., are disposed in the same position as on the belt conveyer11.

A pair of electrically actuatable vibration generators23, which are disposed spaced apart, is situated between the support unit17and the supporting structure21(FIG. 3) of each gripper3,5,7,9. In operation, they generate a vibration, whose vibration direction is illustrated inFIG. 3by a double arrow25. The vibration moves the ampoules13back and forth in their longitudinal direction.

The supporting structure21of each gripper3,5,7,9can be rotated about a horizontal pivot axis27, seeFIG. 3. For this purpose the supporting structure21of each gripper3,5,7,9is connected to a drive motor29(FIG. 2). After loading four container cards14of, in each case, four ampoules13that hang vertically downwards, as is shown inFIG. 2, on the gripper3, the carousel1turns the gripper390° counter-clockwise, so that the gripper3reaches a position aligned with a first test station31, in which the gripper5was previously situated. The gripper5simultaneously moves into a second test station33. During this rotation step, the drive motor29of the gripper3moves the supporting structure21by 90° so that, at the first test station31the container cards14and the ampoules13reach a horizontal position, in which the container bodies are oriented away from the carousel1. In the first test station31, a lighting device in the form of an LED panel35, which extends over the entire area of the upper side of the horizontally lying ampoules13, seeFIG. 2, is situated above the ampoules13. Only the LED panel35belonging to the first test station31is visible inFIG. 2. Below the ampoules13, cameras37are provided as detectors for the light emitted by the LED panel35and passing through the horizontally lying ampoules13from top to bottom. One camera37is provided for each of the four container cards14, which each hold four ampoules13. In the simplified block depiction ofFIG. 1, the four cameras37belonging to the first test station31are illustrated by a camera block designated by the reference numeral38and, instead of the four container cards14each having four ampoules13, only one ampoule13is shown for every container card14.

In operation, when the first test station31is reached, the vibration generators23oscillate the support unit17with the ampoules13, before the cameras37are actuated to take pictures. This actuation of the cameras occurs after the vibration generators23have been stopped, with a rest period elapsing before each camera37takes a first picture. During the rest period, the fluid of the ampoules13, which had been oscillated, settles, so that only freely floating particles, which are to be detected, are in motion or have changed their position. Mobile shadows in fluid in motion could otherwise be wrongly interpreted as dirt particles. Immediately after the fluid motion is stopped, which occurs approximately 500 ms after the oscillation has come to an end, the cameras37take a first picture of the assigned container card14. The four ampoules13of each card14are irradiated from top to bottom. The first picture is followed by additional vibration and picture cycles at short intervals, for example, three additional pictures in a range of 200 ms. The entire picture series of four pictures, including the prior rest period, is then completed within approximately one second, and at most within two or three seconds.FIG. 4shows an example of a corresponding series of four pictures, taken by one of the four cameras37, i.e. four pictures of the same container card14are thus shown.

By an additional rotational motion of the carousel1by 90°, the respective gripper is subsequently moved out of the first test station31and into the second test station33. The ampoules13remain in the same horizontal position. In the second gripping station33, the cameras37are situated, as can be seen fromFIG. 2, above the support unit17with the ampoules13, while the illuminating LED support panel35is situated below. The cameras37detect the radiation that passes through the ampoules13from bottom to top. In the second test station33, the test cycle takes place in a similar way to the first test station31, i.e. contains an oscillation, followed by a damping phase in the range of approximately 500 ms and a subsequent picture series comprising four pictures and vibration cycles.

In an additional rotation of the carousel1by 90°, the gripper which was previously located in the second test station33, which is the gripper7depicted inFIG. 2, moves to the next output station34on the test section. During the motion, the associated drive motor29conducts a pivot motion about the axis27(FIG. 3), so that the container cards14in the output station34hang vertically downwards, i.e., have the same orientation as in the loading station30. If the evaluation of the pictures taken in the first test station31and the second test station33find that the ampoules13are free from defects, the gripper moved into the output station34, which is the gripper9in the figures, deposits the container cards14onto an output conveyor41, which is depicted only in a schematic representation inFIG. 1. The output conveyor41moves the faultless container cards14in the transport direction indicated by arrow43. If the test has found a dirt particle present, no container card14containing the defective ampoule13is deposited on the output conveyor41. Instead, this container card14is, as illustrated inFIG. 1by arrow45, removed from the conveyor line of the output conveyor41and moved off to the side as defective product, as shown inFIG. 1using arrow45.

With a duration of the test sequence of the test stations31and33of approximately 1,500 msec, including a rest phase of 500 msec and a subsequent picture series, the apparatus according to the invention can be operated with a throughput of ampoules13to be tested that corresponds to the production speed of standard BFS systems for generation of ampoule-type container products. The test apparatus according to the invention can then be directly integrated into the production line.

With the different motion patterns that are shown for particles of different types and densities, such as metal particles or plastic particles, once the fluid has settled following prior oscillation, a high level of testing reliability is obtained using the apparatus according to the invention. In particular, picture series are taken once for a camera position above the horizontal ampoules13and with a focus on the fluid surface, and once for a camera position from below with a focus on the lower container wall. Metal particles due, for example, to the BFS production equipment in the form of abraded material, are usually found in the region of the lower container wall owing to their density, are not transparent and are high-contrast and easily detectable because of the lower camera37, which is focused on the container wall.

Plastic particles, such as PP material, which can derive from the container material in the BFS filling method, are semi-transparent and have lower contrast. They preferably float on the fluid surface and are reliably detectable, despite their low contrast, by the upper camera37focused on the fluid surface. Plastic particles floating in the vicinity of a container wall also tend to be attracted, so to speak, by the wall next to them and tend to adhere to the wall, which identifies them as plastic particulate material.

FIG. 4shows the picture series of a single container card14. In the example shown, which was captured using a camera located below and focused on the lower container wall of the ampoules13, a metal particle47can be detected, which moves to the right and slightly in the direction of the ampoule neck49in the picture sequence. The container card14shown inFIG. 4shall therefore be removed from the conveyor line of the output conveyor41in the output station34and be taken in the direction of the arrow45.

For the evaluation of the picture series shown by way of an example inFIG. 4, the image recognition methods known from the prior art can be used, such as grey value transformation, point operators and/or blending methods. In doing so, the image series captured once from the bottom to the top and once from the top to the bottom are reconciled. In addition, a comparison can be carried out using reference pictures showing contamination-free containers and permitting a calibration of the image recognition system used.