TESTING DEVICE FOR TESTING AT LEAST ONE PREFORM, STRETCHING BLADE MACHINE AND METHOD FOR TESTING A PREFORM

Description

[0001] The invention relates to a testing device for testing a preform, a stretch blow molding machine and a method for testing a preform.

[0002] Preforms, also called pre-formed parts, are generally pre-shaped materials that are frequently used as intermediate products in the prior art and processed into a finished product in a final production step. One production process that shapes preforms into hollow bodies is the stretch blow molding process, also known as blow molding. The stretch blow molding process is used in particular to manufacture plastic containers, especially bottles, from thermoplastic materials. In a first process step, the preform, which is in particular a pre-shaped plastic sleeve, is heated to a processing temperature of preferably 90 °C to 120 °C. The preforms generally have a functional area for holding them in a preheating zone. In preforms used for bottle production, the functional area is preferably integrated into a support ring of a threaded neck.In a second process step, the preform is placed in a blow mold. In stretch blow molding machines, a stretching bar is inserted into the preform, stretching it longitudinally. Additionally or alternatively, a process gas is introduced into the preform, causing it to expand transversely and / or longitudinally until its outer walls contact the walls of the blow mold. Blow molding processes are known that first apply a primary pressure of the process gas, followed by a secondary pressure. Finally, the formed hollow body is vented and ejected from the blow mold.

[0003] Various methods for quality assurance are known in the prior art, which determine the quality of a preform based on test criteria. In particular, sensors are used for quality control of the preform. Generally, a first sensor is used to measure the height of the support ring. Additionally, a second sensor is usually used to verify the wobble. Furthermore, a third sensor is used in the prior art to monitor the preform's position in a preform holder. A fourth sensor, in particular a camera, is used in the prior art for inspecting the sidewalls of the preform. Finally, a fifth sensor, in particular a second camera, is used in the prior art to check the color of the preform, and / or a sixth sensor, in particular a third camera, is used to check the length of the preform.In other words, the prior art employs a variety of sensors to determine the test criteria of a preform. Furthermore, verification of these test criteria during a heating phase of the preform is also known in the prior art.

[0004] The quality of a preform can be checked before it is expanded. This allows preforms that do not meet the quality requirements to be removed from the process before expansion.

[0005] WO 00 2020 177 982 A1 discloses a method for product control in a stretch blow molding and / or bottling plant and a corresponding production plant. According to this method, blank parameters of blanks prepared for stretch blow molding are automatically measured, and the initial data obtained is stored. Furthermore, at least the bottle parameters of stretch blow molded empty and / or subsequently filled bottles are automatically measured, and optionally, machine malfunctions occurring during stretch blow molding and / or filling are automatically detected. The resulting data is individually assigned to the blanks and stored. Finally, at least one rejection criterion, applicable in subsequent production operations, is calculated based on a data analysis of the stored initial data to decide whether to reject defective blanks or bottles.By automatically updating the calculation of the rejection criterion, taking into account initial and result data acquired during production, product quality can be continuously improved through the processing of an increasingly larger amount of data in the sense of self-optimization, and the frequency of production failures can be reduced.

[0006] DE 000010 259 589 B3 discloses a method and a device for producing hollow plastic bodies by blow molding heated preforms, wherein the preforms are inspected before heating and at least some of the defective preforms are heated and only rejected after heating. For inspecting the preforms, an optoelectronic inspection station is arranged upstream of a rotating section of the feed star wheel. The inspection station comprises a stationary CCD camera with optics and a lighting device positioned above the path of movement of the preforms. The camera generates an image of the mouth and the support ring of each passing preform. The image is analyzed and classified in real time by a connected electronic evaluation unit.A first error signal is generated if there are defects in the sealing surface, the support ring, and / or a slightly oval opening. A second error signal is generated when a preform with a strongly oval, closed, or only partially open opening is inspected, regardless of whether the sealing surface and support ring are damaged or not. Further generic devices and methods are described in patents EP3181328A1, EP2112502B1, and US2023 / 120081A1.

[0007] The current state of the art has the disadvantage that a large number of sensors and cameras are used to inspect the preform. The resulting test setup is complex. High-quality inspections are essential to ensure high production standards. Consequently, there is a need for an improved testing system to verify a variety of geometry-related and material-related test criteria for preforms, particularly those intended for production using stretch blow molding.

[0008] The purpose of the invention is to improve the state of the art.

[0009] The problem is solved by a test device for testing at least one preform, comprising an optical sensor, an evaluation unit with a data input and a data output, wherein the evaluation unit is connected to the optical sensor via the data input for sensor data exchange, wherein the test device is assigned a holding device designed to hold the preform and which guides the preform to a first position in a first predefined orientation at a first time point and guides the preform to a second position in a second predefined orientation at a second time point point.wherein the test device is configured to determine first sensor data of the preform at the first time using the optical sensor and to send it to the evaluation unit via the data input, and wherein the second sensor data of the preform is determined at the second time using the optical sensor and to send it to the evaluation unit via the data input, wherein the evaluation unit is configured to determine compliance with a first test criterion based on the first sensor data and compliance with a second test criterion based on the second sensor data.

[0010] Using exactly one optical sensor, sensor data can be determined which can be used to test both the first and second test criteria.

[0011] Advantageously, the maintenance effort of the test equipment is reduced by reducing the number of sensors, in particular to a single optical sensor. Along with the reduction of sensors, the reliability of the test equipment and / or the test procedure is improved. The use of a single optical sensor, in particular, advantageously reduces the complexity of the test equipment and / or the complexity of the arrangement of its elements.

[0012] By arranging the preform to be tested in a first and a second orientation according to the invention, a test that considers essentially the entire circumference of the preform is advantageously achieved. Thus, or additionally by using suitable test algorithms, a high quality of the test results is ensured. Finally, the test device according to the invention advantageously enables the testing of a multitude of geometry-related, material-related, and / or other test criteria.

[0013] A key idea is that a complex preform inspection is carried out using multiple test criteria, particularly by means of essentially a single optical sensor. The following terms will be explained:

[0014] A "testing device" is, in particular, a setup designed to verify a predefined criterion. The testing device can determine a measured value of the criterion on a defined test item, in this case a preform, either manually or automatically. Additionally or alternatively, the testing device is configured to assign the measured value to a quality range predefined for the criterion. This predefined quality range may include a confidence interval. Test items whose measured values ​​lie within the confidence interval can be recorded as "tested" in a database.

[0015] A "preform" is understood to be, in particular, a pre-shaped hollow body from which a container can be manufactured, especially using a blow molding machine. The container can be a bottle and / or a drinking vessel. The transformation of the preform into the container is achieved, in particular, by increasing the volume of the preform's interior while simultaneously decreasing its wall thickness. In other words, the container is a fully formed preform. A preform is also called a preform. The preform can be made of plastic, especially thermoplastic. The thermoplastic can be, for example, PET, PVC, or PP.

[0016] In one embodiment, the preform has a fixing area and a forming body. The fixing area is not affected by the expansion of the forming body. The preform can further have a support ring for mounting the preform, particularly for mounting it in a holding device. The support ring can be the fixing element and / or a component thereof. Additionally or alternatively, the preform has a threaded neck. The support ring is particularly located on the neck. Finally, the forming body can be configured to be expanded, particularly at a predefined process temperature, by means of an internal pressure generated using a process gas, in the direction of a predefined blow mold contour until the outer walls of the preform are in full contact with the blow mold contour. The process gas can, for example, be compressed air.Additionally or supplementarily, the expansion is achieved using a mechanical element, in particular a pull bar. The fixing area on the preform advantageously ensures a secure positioning of the preform on a machine element before, during, and after demolding.

[0017] The preform has, in particular, a longitudinal and a transverse extent and is essentially rotationally symmetrical with respect to its vertical axis, which lies centrally within the preform and is oriented along its longitudinal extent. The preform has a height of, in particular, 2 cm to 20 cm, and more specifically, 4 cm to 7 cm, along its vertical axis. The wall thickness of the preform is, for example, 0.1 mm to 10 mm, and more specifically, 0.5 mm to 5 mm. The wall thickness of the container is, in particular, 0.2 mm to 10 mm. The container can have a volume of 0.1 l to 20 l.

[0018] The first predefined orientation of the preform can be characterized by a first angle of the preform relative to its vertical axis, and the second predefined orientation by a second angle relative to its vertical axis. Additionally or alternatively, a third predefined orientation can be characterized by a third angle relative to its vertical axis. Further orientations with corresponding angles of the preform around its vertical axis can be defined. An angle is understood to be, in particular, a rotation angle around the vertical axis of the preform. Specifically, the angle indicates a rotation around the vertical axis relative to the zero position of a rotation around the vertical axis of the preform.

[0019] The first degree of angle can correspond to the second degree of angle and / or a further degree of angle. In other words, a stationary optical sensor is particularly exposed to a first projection surface of the preform located at the first position with the first orientation and a second projection surface of the preform located at the second position with the second orientation. The same applies to the preform located at the third or any further position. The first orientation can correspond to the second orientation and / or a further orientation. In other words, the preform particularly has a first predefined orientation at the first position and a second predefined orientation at the second position, so that, advantageously, two projection surfaces of the preform are exposed to the optical sensor during the inspection process.

[0020] In one embodiment, the second angle is smaller than the first angle by 30° to 90°, particularly 40° to 80°, and preferably 60°, in a first direction of rotation. The third angle is also smaller than the second angle by 30° to 90°, particularly 40° to 80°, and preferably 60°, in the first direction of rotation. By changing the angle of the first angle relative to the second angle and the second angle relative to the third angle by 60°, a substantially complete exposure of the entire outer surface of the preform to the optical sensor is advantageously achieved. Thus, when all three orientations of the preform are detected by the sensor, the respective projections are advantageously captured, which together provide a substantially complete detection of the entire outer surface of the preform.

[0021] By increasing the number of different preform orientations, each with a different angle, and particularly with regard to achieving cumulative coverage of the preform's total surface area, an overlap of the projection surfaces can advantageously be achieved. An overlap of the projection surfaces can offer advantages in terms of data analysis.

[0022] The first and second positions are located at predefined points on the test setup. Additionally or alternatively, the first and second positions lie directly within the detection range of the optical sensor. A third position and further positions can be defined, exhibiting characteristics of the first and / or second positions. Alternatively or additionally, a position of the preform lies outside the detection range of the optical sensor of the test setup. By using a mirror, the detection range of the optical sensor can be extended such that a position lying outside the detection range of the optical sensor is indirectly included within the detection range of the optical sensor of the test setup.By arranging a mirror, the detection range of the optical sensor is advantageously extended and / or obstructions to the view, for example caused by machine elements, can be eliminated. Finally, by arranging a mirror, two projection surfaces of the preform can be advantageously captured simultaneously with essentially a single sensor.

[0023] If the first position is different from the second position, there is generally a transport path for the preform being tested between the two positions. In this case, the second time point necessarily occurs after the first.

[0024] The first position can correspond to the second position. In this case, the preform can be oriented at the common first and second positions at a first time point, and a second orientation can be oriented at the common first and second positions at a second time point. If the first orientation also corresponds to the second orientation, the second time point can correspond to the first time point. The preform can be in the middle of a movement at the first, second, and / or third time point. In other words, the sensor data is acquired at at least one of the aforementioned time points during the transport of the preform. Advantageously, the process is not interrupted during data acquisition in this way.

[0025] Alternatively or additionally, the preform can be temporarily stationary at the first, second, and / or third time point. In other words, the movement of the preform can be interrupted at at least one of the recording times. Advantageously, sharper images can be obtained during a temporary rest of the preform.

[0026] The preform may not yet have been introduced into the first heating zone of a stretch blow molding machine at the first, second, and / or third time point, may be located within the first heating zone, may be located between the first heating zone and a second heating zone, may be located within the second heating zone, and / or may have been removed from the second heating zone. In particular, the preform, or multiple preforms, may be located in a storage area before the first heating zone and after the second heating zone. Naturally, the number of heating zones is machine-dependent and can be reduced or increased accordingly. In other words, at least one of the time points at which the optical sensor acquires sensor data may coincide with a heating phase of the blow molding process. Additionally or alternatively, at least one of the time points may be located before a heating phase of the blow molding process.Finally, at least one of the time points can occur after a heating phase of the blowing process. Advantageously, the time points can be defined in such a way that sensor data from test criteria potentially affected by heating are acquired at an optimal time.

[0027] A "heating phase" refers specifically to a phase of a stretch blow molding process in which the preform is preheated to a predefined process temperature. This predefined process temperature is typically between 90°C and 160°C.

[0028] An "optical sensor" is understood to be, in particular, a sensor that acquires optical data. Optical data is also referred to as image data. The optical sensor is specifically designed to acquire optical data from a test element. An example of an optical sensor is a camera, especially a CCD camera. The optical sensor also or alternatively includes a control element. This control element is configured, for example, to trigger data acquisition by the optical sensor, to adjust the camera's zoom, and / or to control the camera's focus. Triggering data acquisition can be coupled with saving an image file.

[0029] The process of saving an image file as initial sensor data occurs primarily at a trigger point. This trigger point can be programmed into the system. Additionally or alternatively, the trigger point can be linked to a device that transports the preform to the first and / or second position, for example, the holding device, the preform guide, or the blow molding machine. Linking the trigger point to the preform transporting device advantageously simplifies the control of the optical sensor's data acquisition.

[0030] A "holding device" is understood to be, in particular, an element designed to hold a preform in a predefined orientation. A predefined orientation is understood to be, in particular, a rotation angle around the preform's vertical axis, starting from a defined initial position. The vertical axis extends along the preform's longitudinal dimension and runs essentially centrally within the preform. The vertical axis is essentially vertically oriented. Additionally or alternatively, the vertical axis may be tilted. Advantageously, when the preform is oriented with a tilted vertical axis, the underside of the preform is revealed to the optical sensor.

[0031] The holding device can temporarily accommodate a preform. For holding the preform, the holding device may include, for example, pliers, a clamp, a mandrel, and / or a retaining ring. The pliers and / or clamp may have a receiving position and a transport position. In the receiving position, the arms of the pliers and / or clamp are specifically designed to allow the insertion of a preform. In the transport position, the arms of the pliers and / or clamp are specifically designed to substantially prevent the preform from slipping out and / or falling out. The receiving position and the transport position may differ substantially with respect to the position of one arm. Advantageously, using a clamp and / or pliers allows for high maneuverability during transport of the preform.

[0032] A mandrel can be designed to hold a preform at an opening in the mandrel. In other words, the preform is applied to the mandrel essentially vertically, with the future container bottom pointing essentially upwards. A conical shape of the mandrel advantageously provides simple and reliable centering of the preform using gravity. The mandrel can also include a locking element that secures the preform in a transport position.

[0033] A retaining ring can be designed to hold a preform against a circumferential support ring of the preform. In other words, the preform is held, in particular, on the underside of the support ring. The diameter of the retaining ring is, in particular, larger than the outer diameter of the preform and smaller than the diameter of the support ring. To insert the preform into a retaining ring, it can be inserted from above, provided that the diameter of the preform is smaller than the diameter of the retaining ring. Additionally or alternatively, the retaining ring is designed to be two-part and / or openable. In a receiving position, opening the retaining ring allows for a significantly larger inner diameter into which the preform can be inserted. Advantageously, using a one-piece retaining ring eliminates the need for additional securing of the preform.

[0034] The opening of a two-part retaining ring, a clamp, and / or pliers can be automated. This automatic opening can be achieved by appropriate actuators controlled by a machine control unit.

[0035] The holding device can be made of metal and / or plastic.

[0036] Positioning the preform within the detection range of the optical sensor is advantageously achieved by adjusting the height of the held preform using the holding device. Alternatively or additionally, the holding device ensures a minimum distance between the preform and the test equipment and / or elements of the test equipment by means of height adjustment.

[0037] The height of the held preform can vary along a transport path. The holding device is configured, for example, by means of a spindle and / or lifting cylinder, to hold the preform at a first height and at a second height that differs from the first.

[0038] A holding device that holds a preform to be tested by the testing device is assigned to the testing device. In other words, an assignment establishes a unique relationship between a defined holding device and the testing device. The holding device can be the testing device, or vice versa. A holding device is assigned to exactly one testing device at a defined point in time. A holding device can also be assigned to several testing devices, either additionally or alternatively.

[0039] Additionally or alternatively, a unique relationship is established between a holding device and a perform held by the holding device. The relationship between the defined preform and the defined holding device, and / or the relationship between the defined holding device and the test equipment, can be stored, for example, in memory. To enable automatic assignment, at least one holding device among a multitude of holding devices can have a unique identification feature.

[0040] The holding device, in particular a control element of the holding device, such as an actuator of the holding device, can be connected to the test equipment, in particular to a control unit of the test equipment. In other words, the control unit of the test equipment can be configured to control the holding device or an element of the holding device. Advantageously, the complexity of the machine control is reduced by controlling the holding device via the test equipment.

[0041] The holding device is connected to the test equipment, either directly or indirectly. Alternatively, or in addition, the holding device may not have any contact with or connection to the test equipment.

[0042] The direct connection of the holding device to the test device can be designed as a fixed connection of the holding device to a base plate of the test device.

[0043] The indirect connection between the holding device and the testing device can be realized by means of a cam, on which the holding device is temporarily and / or permanently arranged. The cam is, in particular, designed as an element of a stretch blow molding machine and / or the testing device. Additionally or alternatively, the indirect connection between the holding device and the testing device can be realized by means of a guide device.

[0044] A holding device designed to be non-contact with the testing equipment can be implemented, for example, using a robot and / or handling machine.

[0045] A "guiding device" is understood to be, in particular, an element that provides a movable connection between the holding device and the test device, wherein the movement is, in particular, a relative movement predefined by the guiding device. The guiding device can be a rail, threaded rod, and / or cam, on which the holding device is arranged, for example, by means of a connecting element, e.g., a screw connection, or by means of a joining manufacturing process, e.g., welding.

[0046] The blow molding machine and / or stretch blow molding machine and / or the testing device and / or the holding device may include the guide device.

[0047] The guiding device is specifically designed to hold one or more holding devices simultaneously and / or to guide them along a predefined transport path. The predefined transport path includes, in particular, the first position of a preform to be inspected, the second position of a preform to be inspected, and / or a multitude of other predefined positions of a preform to be inspected. Additionally or alternatively, the guiding device is designed to rotate the holding device or multiple holding devices simultaneously about a central axis of the holding devices, an axis oriented parallel to the central axis of the holding devices, and / or a rotation axis inclined to the central axis of the holding devices. The guiding device can be the rotating device and / or comprise the rotating device.

[0048] The guide mechanism can be designed as a circular track, also called a carousel. The circular track can correspond to the heating area of ​​a blow molding machine and / or an element of the heating area.

[0049] In In one embodiment, the holding device is arranged on a rotary device. The rotary device is specifically designed to rotate the holding device and, consequently, a preform arranged within the holding device. The rotation can be continuous and / or discontinuous. Discontinuous rotation occurs, for example, for a predefined duration and / or until a predefined rotation angle of the holding device and / or the held preform is reached.

[0050] The axis of rotation around which the rotary device rotates essentially corresponds to the vertical axis of a held preform and / or is oriented parallel to the vertical axis of the held preform. The axis of rotation may also be inclined relative to the vertical axis of the preform, either additionally or as an alternative.

[0051] Rotation by means of the rotary device can be performed actively in response to a control command. To implement active rotation of the holding device, the rotary device can incorporate actuators. Active rotation can also be achieved additionally or alternatively using magnetic rotary elements. Active rotation of the holding device, and thus of the preform arranged within it, advantageously allows for precise adjustment of the preform's orientation at a predefined time.

[0052] Additionally or alternatively, rotation can occur passively. To implement passive rotation, the rotating device can, for example, include chains with sprockets, belts with pulleys, and / or a toothed pulley with a cam. A passive rotating device advantageously utilizes elements of the stretch blow molding machine and / or the testing equipment. Since the movement of the machine elements is known, the respective orientation of the holding device and / or the respective preform can be derived from this.

[0053] Finally, the rotary device can also be configured for both active and passive rotation of the holding device. A combined implementation of active and passive rotation using the rotary device advantageously allows for a simple orientation of the preforms during normal operation and additional positioning of a preform arranged in a holding device during verification operation, particularly to take additional or repeated sensor readings, which can be used especially for further validation of test criteria.

[0054] In one embodiment, the holding device can include the rotating device. Advantageously, this reduces maintenance requirements.

[0055] An "evaluation unit" is understood to be a device for the program-based evaluation of sensor data, for example, optical sensor data. This program-based evaluation can be performed using predefined algorithms. The evaluation unit has, in particular, a data input and a data output. The evaluation unit is connected to other elements, such as sensors, displays, memory, etc., via the data input and / or the data output, enabling the exchange of sensor data. The evaluation unit is connected to the optical sensor of the test equipment via the data input and / or receives sensor data from the optical sensor via the data input. Alternatively or additionally, the evaluation unit is configured to initiate the acquisition of the first sensor data and / or the second sensor data using the optical sensor. Advantageously, the evaluation unit can also initiate a follow-up inspection, if necessary.

[0056] The evaluation unit is configured to evaluate received sensor data from a preform based on at least one test criterion. Additionally or alternatively, the evaluation unit is configured to simultaneously receive and / or evaluate sensor data from multiple preforms. Finally, the evaluation unit can be configured to evaluate received sensor data based on a multitude of test criteria, particularly simultaneously. Additionally or alternatively, the evaluation unit stores the result(s) of the evaluation. Finally, the evaluation unit can be configured to process image segments from an image file captured by the optical sensor in such a way that individual images are available for each preform and / or that image segments relevant for testing are selected.

[0057] The evaluation unit is connected via its data output, in particular to a control unit of the testing device and / or the blow molding machine. Advantageously, the evaluation unit transmits the test result to a preform via a signal, and defective preforms are rejected and / or re-tested based on this signal, either before and / or after expansion. Additionally or alternatively, the evaluation unit can be connected to a memory via its data output, or it can include a memory and be configured to store test results.

[0058] The "first test criterion" and / or the "second test criterion," or any further test criterion, is in particular a property of the preform that influences the quality of the container. A test criterion can be geometry-based. Additionally or alternatively, a test criterion can be material-based. Finally, a test criterion can relate to a quality aspect.

[0059] The test criterion can be, for example, a "support ring height", a "wobble", a "color" of the preform, a "length" of the preform and / or a "condition of a side wall" of the preform.

[0060] A "support ring height" is, in particular, a distance of a support ring of the preform from a first end and / or a second end of the preform.

[0061] The "wobble" is in particular a rotational symmetry of a sub-area of ​​the preform, especially the expansion area of ​​the preform.

[0062] A "color" of a preform can be defined by a color value and / or a gray value and / or a degree of transparency.

[0063] The "length" of the preform is preferably 2 cm to 20 cm.

[0064] The "surface finish" of a preform is characterized, for example, by a smooth surface. A smooth surface essentially has no ridges, bumps, indentations, and / or scratches.

[0065] A confidence interval can be predefined for testing the first and / or second test criterion. Advantageously, a confidence interval defines a measurement range within which a test criterion is considered "passed." This allows minor measurement inaccuracies or errors to be compensated for or tolerated.

[0066] In one embodiment of the testing device, the optical sensor is a camera. The preform can be located in the same space as the camera and / or in a space enclosed by the camera, in particular an enclosed but visible space. Spatial separation of the preforms and the camera advantageously prevents interference, especially with temperature-sensitive camera components, and thus increases the camera's service life.

[0067] The camera is specifically designed to capture image data of a preform within a predefined detection range. The camera can also be configured to capture sensor data used for testing a variety of criteria. Furthermore, the camera can be configured to simultaneously capture sensor data from a first and a second preform. Advantageously, a single camera can provide image data for multiple preforms within its detection range. Additionally, the various measurement positions of the preforms can be optimally captured through appropriate camera settings.

[0068] Additionally or alternatively, the camera is rotatable about a substantially horizontal first camera axis and / or a substantially vertical second camera axis and / or a third camera axis oriented substantially perpendicular to the first and second camera axes. The camera can be actively rotatable, thus advantageously enabling an adjustable detection range.

[0069] The camera can be fixed and / or movable on a mount. Additionally or alternatively, lighting is arranged on or around the camera, illuminating a detection area that is essentially in front of the camera. Finally, a screen or background can be arranged on the test device, designed to limit the depth of the detection area. In other words, the screen provides a background for the test object to be captured by the camera. Advantageously, the screen allows for the acquisition of more optimal sensor data for preform testing.

[0070] In one embodiment, the camera is a color camera and / or a monochrome camera and / or a CCD camera and / or an infrared camera. Using a commercially available camera advantageously results in lower production costs.

[0071] The test device may include an output unit. The output unit is connected to the evaluation unit of the test device, in particular via the data output, for the exchange of sensor data. The evaluation unit sends a signal to the output unit, the signal representing, in particular, compliance with the first test criterion and / or compliance with the second test criterion.

[0072] The output unit can be configured to output an optical signal, for example using a light source or a screen, an acoustic signal, for example by means of a loudspeaker, and / or a haptic signal. The signal output is preferably designed such that a worker perceives the signal and can intervene in the production process if necessary. Additionally or alternatively, the output unit includes a database and / or has access to a database and is configured to store the test results.

[0073] In another aspect, the task is solved by a stretch blow molding system comprising a heating unit, a stretch blow molding machine, and a testing unit for inspecting at least one preform. A stretch blow molding machine can also be a blow molding machine. The stretch blow molding machine is arranged upstream of the heating unit. In other words, the stretch blow molding system includes, in particular, an input area for preforms in holding fixtures, an inlet area to the heating unit, a heating area within the heating unit, an outlet area from the heating unit, a storage area after the heating unit, an inlet area to the stretch blow molding machine, a stretching and / or stretch blow molding area, and / or an outlet area from the stretch blow molding machine. The heating unit includes, in particular, a first heating element, a second heating element, and / or a final heating element in the upstream heating area.The transport of the preforms to, within, and / or after the heating area can be accomplished using transport devices of the stretch blow molding system and / or transport devices of the stretch blow molding machine, which advantageously position the preform at the first, second, and / or third position. This allows for a reduction in the complexity of the testing equipment and the exploitation of synergies with lower manufacturing costs.

[0074] The test device can be designed as an integral part of the heating device. In this case, the test device is arranged in the heating device, particularly in the inlet area of ​​the preforms, and especially upstream of a first heating element of the heating device.

[0075] In another embodiment, the testing device in the stretch blow molding machine is arranged downstream of the preforms entering the heating unit and upstream of an exit section from the heating unit. The entry section is specifically located upstream of a first heating element, and the exit section is specifically located downstream of a last heating element. In other words, the testing takes place simultaneously with the heating of the preforms and / or their transport through the heating section. Since the preforms are subject to rotation during heating to achieve uniform heating, the process-related movement of the preforms can advantageously be used to realize the first, second, and / or third positions. This results in less implementation effort for the testing device, as existing machine elements of the stretch blow molding machine are used.

[0076] In another embodiment, the stretch blow molding machine incorporates a mirror. This mirror is specifically designed to enable indirect data acquisition of a preform at a fourth position, which lies outside the detection range of the optical sensor of the inspection device. In other words, the detection range of the optical sensor is extended by means of the mirror. Advantageously, this allows the optical sensor to detect additional positions, including those obscured by machine elements. This simplifies the integration of the inspection device into a blow molding machine and / or system, and advantageously eliminates the need for additional sensors to cover the extended detection range.

[0077] In another aspect, the task is solved by a method for testing a preform inserted into a holder of a testing device in a stretch blow molding machine. In a first step, the preform is positioned in a first orientation. In a second step, initial sensor data from the preform is acquired using an optical sensor and transmitted to an evaluation unit. In a third step, the preform is positioned in a second orientation, and in a fourth step, further sensor data from the preform is acquired using the optical sensor and transmitted to the evaluation unit. In a fifth step, the evaluation unit determines whether the initial sensor data meets the first test criterion and whether the second sensor data meets the second test criterion.In a sixth step, the evaluation unit sends a release signal to a control unit of the stretch blow molding machine, which represents the determination of the first test criterion and the second test criterion.

[0078] Advantageously, the preform is thus checked using sensor data acquired by means of essentially an optical sensor, and preforms that do not meet the quality requirements can advantageously be rejected before expansion.

[0079] In one embodiment, the preform is additionally positioned in a third orientation. Third-party sensor data from the preform is acquired using the optical sensor and transmitted to the evaluation unit. The evaluation unit determines whether the third-party sensor data fulfills a third test criterion and issues a second release signal to the control unit of the stretch blow molding machine, with the second release signal representing the fulfillment of the third test criterion. Advantageously, the first orientation corresponds to an angle of 0°, the second to an angle of 120°, and the third to an angle of 240°, so that the entire surface of the preform is inspected.

[0080] The features of the second and third aspects, combinations of features, and the advantages arising from them correspond to those mentioned in connection with the first-mentioned aspect of the invention.

[0081] The invention will now be explained in more detail using exemplary embodiments. These will show... Figure 1 a schematic representation of a testing device, Figure 2 a flowchart of a method according to the invention for testing a preform inserted into a holder of a testing device in a stretch blow molding machine, Figure 3 a top view of a stretch blow molding machine with integrated testing device and Figure 4 a schematic side view of a testing device with a mirror.

[0082] A test device 102 has a base plate 129. A linear guide 107 is arranged on the base plate 129 as a guide device. A holding device 105, movable along a guide path of the linear guide 107, is arranged on the linear guide 107. The holding device 105 is configured to hold a preform 101 by means of a clamp. The guide path comprises at least a first position 121 with a first rotation of the preform 101 of 60° about its own axis and a second position 123 with a second rotation of the preform 101 of 120° about its own axis. Furthermore, a camera 103 is rotatably mounted on a tripod 125 on the base plate 129.

[0083] The detection range of the camera 103 includes at least a first recording position of the preform 101 held by means of a holding device 105 at the first position 121 and a second recording position of the preform 101 held by means of a holding device 105 at the second position 123. Furthermore, a screen 117 is arranged on the base plate 129 opposite the camera 103.

[0084] In other words, during sensor data acquisition, the Preform 101 is positioned between the screen 117 and the camera 103. The detection range of the camera 103 also encompasses at least a portion of the screen 117. The screen 117 thus limits the depth of the detection range of the camera 103.

[0085] Furthermore, the test equipment 102 includes a computer 109 with a data input 111 and a data output 113. A camera 103 is connected to the data input 111 via a first data cable 115A. The camera 103 transmits image data acquired via the first data cable 115A to the computer 109 via the data input 111. A display screen 119 is connected to the data output 113 of the computer 109 via a second data cable 115B.

[0086] To check the length of the preform 101, as the first test criterion, the preform 101 is moved to the first position 121 at a first time point by the interaction of the holding device 105 and the linear guide 107, and the camera 103 records initial sensor data at a second time point, which shows the preform 101 in its first orientation. Upon receiving the recording, the camera 103 transmits the initial sensor data to the computer 109 via the data input 111.

[0087] To examine the condition of the side wall of the preform 101, as a second test criterion, the preform 101 is moved at a third time by the holding device 105 in conjunction with the linear guide 107 to the second position 123, and at a fourth time the camera 103 records second sensor data of the preform 101 located at the second position 123. Upon receiving the recording, the camera 103 transmits the second sensor data to the computer 109 via the data input 111.

[0088] At a fifth time point, computer 109 uses an image analysis program to determine whether the first test criterion, "length," and the second test criterion, "condition of the side wall of preform 101," have been met. Subsequently, at a sixth time point, computer 109 transmits a signal to display screen 119 via data output 113 and using the second data cable 115B. This signal represents the confirmed compliance with the first test criterion, "length," and the second test criterion, "condition of the side wall of preform 101." Upon receiving the signal, display screen 119 shows a stored icon at a seventh time point, which represents the release of preform 101.

[0089] In a process for inspecting a preform inserted into a holder of a testing device in a stretch blow molding machine, the preform is first positioned at a 0-degree orientation. Then, initial sensor data from the preform is acquired using a CCD camera and transmitted to a computer. Next, the preform is positioned at a 180-degree orientation, and further sensor data is acquired using the CCD camera and transmitted to the computer. Using an image analysis algorithm, the computer automatically determines that the initial sensor data meets a third test criterion, "diameter," and the second sensor data meets a fourth test criterion, "gray value."In response to the detection, the computer sends a release signal to a control unit of the test device 600, where the release signal represents the detected fulfillment of the third test criterion "length" and the fourth test criterion "gray value".

[0090] During a Figure 3 In the arrangement of the test device 102 shown in a stretch blow molding machine 131 with heating device 133, the test device 102 is designed as a component of the heating device 133. The heating device 133 has an inlet area 137 and, upstream, a heating area 143 and an outlet area 145. The heating area 143 has a first heating element 139 at the beginning of the heating area 143. Following the first heating element 139, the heating area 143 has six further heating elements upstream and, after a reversal of the direction of transport, an eighth to thirteenth heating element and finally a last heating element 141.

[0091] A preform 101 is placed in a holding device 105 at the beginning of the infeed section 137, and the holding device 105 is subsequently transported through the heating section 143 to the discharge section 145 by means of a chain drive. The stretch blow molding machine 131 has a CCD camera 103, which records sensor data of the preform 101 located in the infeed section and sends it to the computer 109 for evaluation. The computer sends a signal to a display screen 119, which represents the evaluation result. At the end of the discharge section 145, the now heated preform 101 is transferred to the stretch blow molding machine 135, which forms the heated preform 101 into a container. Alternatively, the stretch blow molding machine 135 can include the heating section 143.

[0092] The preform 101 to be tested is located in Figure 4At a fourth position 149, outside the direct detection range of the camera 103, a machine component 151 obstructs a direct view. A mirror 147 is arranged on the base plate 129 by means of a holder 153 such that an image of the preform 101 is visible to the camera 103 via the seal 147. Reference symbol list

[0093] 101 Preform 102 Testing device 103 Camera 105 Holding device 107 Linear guide 109 Computer 111 Data input 113 Data output 115A First data cable 115B Second data cable 117 Screen 119 Display screen 121 First position 123 Second position 125 Tripod 129 Base plate 131 Stretch blow molding machine 133 Heating device 135 Stretch blow molding machine 137 Infeed area 139 First heating element 141 Last heating element 143 Heating area 145 Outfeed area 147 Mirror 149 Fourth position 151 Machine component 153 Holder 100 Positioning the preform at a first position 200 Determining first sensor data 300 Positioning the preform at a second position 400 Determining second sensor data 500 Verifying fulfillment of a third and a fourth test criterion Test criterion 600: Output of a release signal

Claims

1. Testing device (102) for testing at least one preform (101), having an optical sensor (103), an evaluation unit (109) with a data input (111) and a data output (113), wherein the evaluation unit (109) is connected to the optical sensor (103) via the data input (111) in order to exchange sensor data, and with a holding apparatus (105) assigned to the testing device (102) which is designed to hold the preform (101) and guides the preform (101) to a first position (121) in a first predefined orientation of the preform (101) at a first point in time and guides the preform (101) to a second position (123) in a second predefined orientation of the preform (101) at a second point in time, characterised in that the testing device (102) is adapted to detect first sensor data of the preform (101) by means of the optical sensor (103) at the first point in time and send it to the evaluation unit (103) via the data input (111), and to detect second sensor data of the preform (101) by means of the optical sensor (103) at the second point in time and send it to the evaluation unit (109) via the data input (111), wherein the evaluation unit (109) is adapted to detect compliance with a first test criterion on the basis of the first sensor data and compliance with a second test criterion on the basis of the second sensor data.

2. Testing device (102) according to one of the preceding claims, wherein the assigned holding apparatus (105) is arranged on a guiding device (107) and / or on a rotating device.

3. Testing device (102) according to one of the preceding claims, wherein the holding apparatus (105) guides the preform (101) to a third position in a third predefined orientation of the preform (101) at a third point in time, and the testing device (102) is further adapted to detect third sensor data of the preform (101) by means of the optical sensor (103) at the third point in time and send it to the evaluation unit (103) via the data input (111), and furthermore to detect compliance with the first test criterion and / or the second test criterion and / or a third test criterion by means of the evaluation unit (103) on the basis of the third sensor data.

4. Testing device (102) according to one of the preceding claims, wherein the second predefined orientation of the preform (101) has a second angular degree of the preform (101) which deviates by 30° to 90°, in particular 40° to 80°, preferably 60°, in a first rotation direction from a first angular degree of the first orientation of the preform (101) and / or wherein the third predefined orientation of the preform (101) has a third angular degree of the preform (101) which deviates by 30° to 90°, in particular 40° to 80°, in particular 60°, in the first rotation direction from the second angular degree of the preform (101).

5. Testing device (102) according to one of the preceding claims, wherein the first test criterion and / or the second test criterion and / or the third test criterion is a support ring height and / or a wobble and / or a colour of the preform (101) and / or a length of the preform (101) and / or a composition of a side wall of the preform (101).

6. Testing device (102) according to one of the preceding claims, characterised in that the optical sensor (103) of the testing device (102) is configured as an imaging camera, in particular a colour imaging camera and / or monochrome camera and / or CCD camera and / or an infrared camera.

7. Testing device (102) according to one of the preceding claims, wherein the preform (101) is moved or at least temporarily stationary at the first point in time and / or at the second point in time and / or at the third point in time and / or is not yet introduced into a first heating area (143) and / or is present in the first heating area (143) and / or is present between the first heating area (143) and a second heating area and / or is present in the second heating area and / or is led out of the second heating area.

8. Testing device (102) according to one of the preceding claims, wherein the testing device (102) further comprises an output unit (119) and the evaluation unit (109) is connected to the output unit (119) via the data output (113) in order to exchange sensor data, wherein the evaluation unit (109) transmits a signal to the output unit (119) which represents compliance with the first test criterion and / or compliance with the second test criterion and / or compliance with the third test criterion.

9. Testing device (102) according to one of the preceding claims, wherein the preform (101) is made of plastic, in particular thermoplastic resin.

10. Testing device (102) according to one of the preceding claims, wherein the preform (101) in particular has a height of 3 cm to 25 cm, in particular 3 cm to 16 cm, and a wall thickness of 0.1 mm to 10 mm, in particular 0.5 mm to 5 mm.

11. Stretch blow moulding system (131) with a testing device (102) according to any of claims 1-10, a heating device (133) for preforms (101) and a stretch blow moulding machine (135) arranged upstream thereof, characterised in that the testing device (102) is configured as a component of the heating device (133) and, in particular, is arranged within the latter in an entry area (137) of the preform (101) before a first heating element (139) of the heating device (133).

12. Stretch blow moulding system (131) according to claim 11, characterised in that the testing device (102) is arranged between the entry area (137) of the preform (101) into a heating area (143) and an exit area (145) of the preform (101) arranged after a last heating element (141) of the heating device (133).

13. Stretch blow moulding system (131) according to claim 11 or 12, wherein the stretch blow-moulding system (131) has a mirror (147) and the mirror (147) is adapted to realise an indirect data capture of a preform (101) which is present at a fourth position (149) outside a detection range of the optical sensor (103) of the testing device (102).

14. Method for testing a preform inserted into a holder of a testing device in a stretch blow moulding machine, comprising the following steps: • positioning (100) the preform in a first orientation. • detecting (200) first sensor data of the preform by means of an optical sensor and transmitting the first sensor data to an evaluation unit. • positioning (300) the preform in a second orientation. • detecting (400) second sensor data by means of the optical sensor and transmitting the second sensor data to the evaluation unit. • determining (500) by means of the evaluation unit that the first sensor data fulfils a first test criterion and the second sensor data fulfils a second test criterion, and • outputting (600) a release signal from the evaluation unit to a control device of the stretch blow moulding machine, wherein the release signal represents the fulfilment of the first test criterion and the fulfilment of the second test criterion.

15. Method according to claim 14, further comprising the following steps: • positioning (400a) the preform in a third orientation. • detecting (400b) third sensor data of the preform by means of the optical sensor and transmitting the third sensor data to the evaluation unit. • determining (500b) by means of the evaluation unit that the third sensor data fulfils a third test criterion, and • outputting (600b) a second release signal from the evaluation unit to the control device of the stretch blow moulding machine, wherein the second release signal represents the fulfilment of the third test criterion.