CONTROL SYSTEM FOR THE QUALITY OF PROCESSING PIPES MADE OF THERMOPLASTIC MATERIAL

Abstract

Described is a control system for the quality of processing pipes made of thermoplastic material, comprising a station for housing at least one pipe to be controlled, a first video camera configured to capture images of a first front scene showing a first longitudinal end of the pipe, and at least a second video camera configured to capture images of a second lateral scene showing the same said pipe in its longitudinal extension.

Claims

1. A control system for the quality of processing pipes made of thermoplastic material, comprising: a housing station for housing at least one pipe to be controlled; a first video camera configured for capturing images of a first front scene showing a first longitudinal end of said pipe; at least a second video camera configured for capturing images of a second lateral scene showing the longitudinal extension of said pipe; a computerised processing unit configured for acquiring said images of said first and second scene and analysing them digitally to obtain information regarding the state of said pipe.

2. The control system according to claim 1, wherein said computerised processing unit is configured to obtain from said images of said first front scene at least one piece of information between the outer diameter of the pipe at said relative first end and the presence of a seal located inside the pipe.

3. The control system according to claim 1, wherein said computerised processing unit is configured for detecting from said images of said second lateral scene information regarding the presence of defects and/or irregularities on the lateral surface of the pipe.

4. The control system according to claim 1, wherein it comprises a lighting unit configured to illuminate at least an inner part of said pipe to be controlled at said relative first end.

5. The control system according to claim 1, wherein it comprises means for rotation of said pipe to be controlled configured for rotating said pipe about a relative central axis to cause different portions of the lateral surface of said pipe to face in succession said second video camera.

6. The control system according to claim 1, wherein it comprises a robotized arm configured at least for picking up said at least one pipe made of plastic material from an accumulation station and for positioning it in said housing station for controlling it.

7. The control system according to claim 1, wherein it comprises a retractable probe designed to be inserted inside the pipe for capturing images of the inner surface of the pipe.

8. A method for controlling the quality of processing pipes made of thermoplastic material, comprising the following steps: preparing a control system according to claim 1, acquiring images of a first front scene of a pipe by capturing a first longitudinal end of said pipe, acquiring images of a second lateral scene of said pipe by capturing a relative longitudinal extension, processing, using said computerised unit, said images of said first front scene to obtain from them at least one piece of information between the outer diameter of the pipe at said relative first end, and the presence of a seal located inside the pipe, processing, using said computerised unit, said images of said second scene to obtain from them information about the presence of defects and/or irregularities on the lateral surface of the pipe.

9. The control method according to claim 8, wherein said processing steps comprise the step of digitally analysing said images of said first and second scene.

10. The control method according to claim 8, wherein said processing steps of comprise the step of comparing said images of said first and second scene with corresponding reference images.

Description

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0026] As already mentioned above, the invention relates to a system for controlling the quality of processing pipes made of plastic material, and in particular those equipped with a bell at the relative end.

[0027] Parameters which can be considered for the purposes of a qualitative assessment of the conformity of plastic pipes equipped with bells at their end are as follows:

[0028] Colour: homogeneous in the case of a compliant product.

[0029] Morphology: the product has a series of parameters which determine the profile of the outer and inner wall (circularity of walls, thickness, size of seal housing, etc.).

[0030] Seal: it may be present inside the bell and, if present, must have a predetermined positioning.

[0031] Logos and markings: these can be present both as printing and as bas-relief.

[0032] Surface processes: these can be present such as in, for example, corrugated pipes.

[0033] Bell: its geometry must not present imprecisions.

[0034] The control system for the quality of processing pipes made of thermoplastic material according to the invention comprises a station for housing at least one or more pipes to be controlled.

[0035] Advantageously, according to a preferred but not exclusive embodiment of the invention, the housing station comprises seats for simultaneously housing four pipes to be controlled.

[0036] Depending on the diameter of the pipes to be controlled and therefore their overall dimensions, the housing station is made to house greater or smaller numbers of pipes to be controlled.

[0037] The control system according to the invention advantageously comprises an automatic or robotized arm configured for picking up the pipes made of plastic material from a storage station and placing them in the above-mentioned housing station for subjecting them to the control.

[0038] A further automatic or robotized arm removes the pipes already controlled to send them to the subsequent production steps if they conform to the quality requirements or reject those pipes which, following the control performed, do not meet the quality requirements.

[0039] The two automatic or robotized arms described above can advantageously be implemented in a single automatic or robotized arm which is able to perform both the respective functions.

[0040] The quality control system according to the invention comprises, positioned at the above-mentioned station for housing the pipes, a first video camera configured for capturing images of a first front scene showing a first longitudinal end of the pipe to be controlled.

[0041] Advantageously, the first longitudinal end is that which has the bell and, when provided, a relative seal.

[0042] The quality control system according to the invention comprises, also positioned at the above-mentioned station for housing the pipes, a second video camera configured to capture images of a second lateral scene depicting the pipe in its longitudinal extension.

[0043] Since the above-mentioned second lateral scene captured by the second video camera clearly cannot with a single shot cover the entire lateral surface of the pipe, means are provided for rotation of the pipe to be controlled configured for rotating said pipe about a relative central axis to cause different portions of the lateral surface of the pipe to face in succession the second video camera.

[0044] In other words, the pipe subjected to control is rotated about its central axis in such a way as to allow the second video camera to capture, by means of two or more shots (or scans), the entire lateral surface of the pipe.

[0045] Alternative embodiments falling within the scope of the inventive concept comprise the presence of a greater number of video cameras, distributed angularly relative to the axis of the pipe in such a way as to provide, in their entirety, an overall panoramic view of the outer surface of the pipe thanks to which the use of the above-mentioned rotation means is no longer necessary.

[0046] The quality control system according to the invention also comprises a computerised processing unit configured for acquiring the images of the first and second scene and analysing them digitally to obtain information regarding the state of the pipe.

[0047] In particular, the computerised processing unit is configured to obtain from the images of the first front scene information such as the external diameter of the pipe at its first end (that is, the one where the bell has been made), its circularity, the presence of a seal positioned inside the pipe.

[0048] It is without doubt possible, from this first scene, to investigate the internal diameter of the pipe at its first end or also the regularity of its thickness or the correct positioning of the seal.

[0049] In particular, the computerised processing unit is configured for detecting from the images of the second lateral scene information such as the presence and extension of defects and/or irregularities on the lateral surface of the pipe.

[0050] Examples of such defects or irregularities are without doubt represented by cracks, fissures, whitenings or non-uniform marks of colour, logos shown incorrectly etc.

[0051] According to preferred embodiments, the control system according to the invention comprises a lighting unit configured to illuminate at least an inner part of the pipe to be controlled at its first end.

[0052] Correct lighting is, in effect, essential for an equally effective acquisition of the images by the video cameras.

[0053] As mentioned, with reference to the pipes made of thermoplastic material equipped with bells, to which the invention preferably relates, the quality control system aims to inspect the zone of the pipe in which the bell has been made and, where provided, the seal has been inserted.

[0054] Alternatively, if the seal is located in a subsequent step, the seat for housing the seal is controlled.

[0055] In addition to the possibility of assessing the conformity of the seat for housing the seal from the outside, that is to say, using the images obtained by the second lateral video camera, specific embodiments of the system comprise the presence of a retractable probe designed to be inserted inside the pipe for acquiring images of the inner surface of the pipe.

[0056] In that way, even though with a limited complication of the system, it is possible to obtain direct images of the seat for housing the seal and also, if necessary, the seal already inserted, in order to assess the correct positioning also in an axial direction.

[0057] For the purposes of this description, the expression “reference image” does not necessarily mean a real image but also a set of parameters which together define the above-mentioned reference image.

[0058] In other words, by way of example with reference to the verification of the presence of cracks or other surface irregularities, the above-mentioned reference image could without doubt consist of an actual, sample-type image captured by the system of a pipe without defects but also, simply, defined by the imposition of the absence of clear irregularities in the colouring of the pipe, if necessary with an extension in length/area greater than predetermined values.

[0059] Similarly, with reference for example to verifying the dimension of the circumference defined frontally of the outer wall of the pipe, the relative reference image may be both a real image of an actual, sample-type, pipe having the desired dimension, and simply a desired diameter value to be compared with that obtained by the system from the detected image of the pipe which is being controlled.

[0060] In yet other words, the processing of the images acquired may proceed both on the basis of a comparison with real reference images and through a digital analysis of the image which may provide, for example, particularly precise information on the dimensions of the pipe but also on the presence of surface defects or irregularities.

[0061] In use, a pipe made of plastic material is positioned at a housing station.

[0062] In this housing station there is a first video camera, oriented in such a way as to capture frontally a first longitudinal end of the pipe, advantageously the one in which the bell has been made, and a second video camera positioned, on the other hand, for capturing images of the lateral surface of the pipe.

[0063] At this point, the above-mentioned computerised processing unit acquires the images of the pipe taken by the above-mentioned first and second video cameras and analyses them digitally.

[0064] The digital analysis of the above-mentioned images provides, as a result, information relative to the status of the pipe, already described above, designed for assessing its processing quality.

[0065] The invention, as well as a system as described above, also relates to a method for controlling the quality of processing pipes made of thermoplastic material, and comprises a plurality of steps.

[0066] A first step is that of preparing a control system as described above.

[0067] A further step is to acquire images of a first front scene of a pipe by capturing a first longitudinal end of the pipe whilst another is to acquire images of a second lateral scene of the pipe by capturing a relative longitudinal extension.

[0068] The two steps of acquiring images just described are advantageously performed by the above-mentioned first and second video cameras.

[0069] The control method according to the invention comprises a step of processing the images of the first front scene to obtain from them at least one piece of information selected between the outer diameter of the pipe at its first end, and the presence of a seal located inside the pipe. The method comprises a further step of processing the images of the second scene to obtain from them information about the presence of defects and/or irregularities on the lateral surface of the pipe.

[0070] Both the above-mentioned steps of processing the images are performed by the computerised processing unit described above.

[0071] The control system and the method according to the invention achieve the preset aims and achieve significant advantages.

[0072] A first advantage is due to the fact that by means of the system and method it is possible to perform an effective control of the production quality of the pipes made of thermoplastic material without the use of human resources and thereby also overcoming the limits linked to the failure of this type of control.

[0073] Another advantage linked to the invention is due to the fact that thanks to the use of video cameras and the connected visual control basically of the end zone where the bell is positioned, it is possible to operate on many different lengths of pipes without this requiring particular modifications to the system.

[0074] The system according to the invention is also simple and inexpensive to make, requiring, in a relative basic form, substantially the presence of two video cameras and a computerised processing unit.