Apparatus for detecting and checking defects on a tire at the end of a production process

Abstract

An apparatus for detecting and checking defects on a tire at the end of a production process, the apparatus comprising a workstation comprising a workbench comprising a rotating table for supporting a tire; a profilometer; a high-resolution color linear camera for scanning outer surfaces of tire tread and tire shoulders; mechanical supports for the profilometer and color linear camera; a data processor for storing and processing data detected by the profilometer and the color linear camera means, for providing a three-dimensional model of a tire, and for management of a database including parameters referring to surface characteristics of defect-free tires; an interface for facilitating interaction between an operator and the apparatus; wherein the profilometer and the color linear camera are configured to operate simultaneously and perform a full scan of all the profiles of inner and outer surfaces of a tire while the tire is in rotation at a controlled speed on the rotating table; and wherein the data processor is adapted to define and classify defects detected, by comparing parameters detected by the profilometer and the color linear camera to at least one corresponding parameter of a defect-free tire of a same type as a tire being tested.

Claims

1. An apparatus for detecting and checking defects on a tire at the end of a production process, the apparatus comprising a workstation comprising: a workbench comprising a rotating table for supporting a tire being tested; a profilometer for scanning and detecting a sequence of images referring to the profile of the internal and external surfaces of the tire; a high-resolution color linear camera for scanning outer surfaces of tire tread and tire shoulders; a mechanical support for the profilometer; a mechanical support for the color linear camera; a data processor for storing and processing data detected by the profilometer and the color linear camera, for generating a three-dimensional model of the tire, and for management of a database including parameters referring to surface characteristics of defect-free tires; an interface for facilitating interaction between an operator and the apparatus; wherein the profilometer and the color linear camera are configured to operate simultaneously and perform a full scan of all the profiles of inner and outer surfaces of the tire while the tire is in rotation at a controlled speed on the rotating table; wherein the data processor is adapted to define and classify defects detected, by comparing parameters detected by the profilometer and the color linear camera to at least one corresponding parameter of a defect-free tire of a same type as the tire being tested.

2. The apparatus according to claim 1 wherein the data processor is adapted to define and classify defects detected by algorithmic comparison of parameters detected by the profilometer and the color linear camera to the at least one corresponding parameter of a defect-free tire of a same type as the tire being tested.

3. The apparatus according to claim 1 wherein the profilometer comprises five profilometer units.

4. The apparatus according to claim 3 wherein the color linear camera comprises two high definition color linear camera units.

5. The apparatus according to claim 1 wherein the apparatus is adapted to complete scanning of one side of a tire in 60 seconds before overturning the tire.

6. The apparatus according to claim 1, wherein the profilometer comprises: at least one profilometer unit for scanning an outer surface of tread of a tire being tested; at least one profilometer unit for scanning an outer surface of a first tire shoulder and a second tire shoulder opposite the first tire shoulder without overturning the tire; at least one profilometer unit for scanning an inner surface of the tread; at least one profilometer unit for scanning the inner surface of a shoulder of the tire and an inner surface of an opposite shoulder without overturning the tire; and at least one profilometer for scanning a surface of a bead of the tire.

7. The apparatus according to claim 6, wherein the color linear camera comprises at least one color camera unit for scanning the outer surface of the tread and at least one color camera unit for scanning the outer surface of a shoulder of the tire and, without the overturning of the same, the surface of the opposite shoulder.

8. The apparatus according to claim 1 wherein the profilometer comprises a plurality of profilometer units, each comprising: a laser device for detecting a profile of the tire; and a linear camera on each profilometer unit, oriented at an inclination between 25° and 45° with respect to the laser device, for continuous acquisition of parameters detected by the laser device.

9. The apparatus of claim 6 wherein each profilometer unit comprises a laser device for detecting a profile of the tire; and a linear camera on each profilometer unit, oriented at an inclination between 25° and 45° with respect to the laser device, for continuous acquisition of parameters detected by the laser device.

10. The apparatus according to claim 7 wherein the linear camera on each profilometer unit is controlled with respect to image acquisition speed, resolution, optics, and filter; and each laser device is controlled with respect to power, distance from a corresponding profilometer linear camera, and tire areas detected referring to the laser device.

11. The apparatus of claim 1 wherein the data processor is adapted to generate the three-dimensional model of the tire based on measurement of height, length, width, and inclination of surfaces.

12. The apparatus of claim 11 wherein the three-dimensional model is of the entire tire surface including tread, shoulders, and beads.

13. The apparatus of claim 1 wherein the data processor is adapted to store 8,000 to 12,000 profiles per tire.

14. A method to perform checking and detecting of surface defects of a tire at the end of a production process by means of the apparatus according to claim 1, where the method comprises the following steps: a. removing a tire to test from a production line and positioning the tire to test on the rotating table of the workbench; b. operating the mechanical supports for the profilometer and the color camera to position the profilometer and color linear camera for scanning the tire to test; c. determining a rotation speed of the rotating table on which the tire is placed, in order to perform its complete 360° scan; d. processing the parameters detected by the profilometer and the linear color camera means, and providing a three-dimensional model of the tire on the basis of the parameters detected; e. characterizing and classifying surface defects, if detected, by comparison of the parameters detected to at least one corresponding parameter of a defect free tire of the same type as the tire being tested; f. stopping and repositioning in the profilometer and linear color camera with respect to starting conditions; g. overturning the tire on the rotating table to allow the scanning of remaining unscanned surfaces; h. repeating steps b, c, d, and e; i. removing the tire and repositioning the tire in a position in the production line that depends on results of the foregoing comparison.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Further features and advantages of the present invention will be apparent in the light of the detailed description of a preferred, but not exclusive, embodiment of a method and apparatus for checking the defects of a tire at the end of the production process, illustrated by way of non-limiting example, with the aid of the accompanying drawings, wherein:

(2) FIG. 1—a layout of the apparatus provided with a single control station;

(3) FIG. 2—a layout of a control station in an apparatus provided with two stations;

(4) FIG. 3—a layout of another control station of the apparatus in FIG. 2;

(5) FIG. 4—a) sections both inner and outer which compose the tire and may present defects, b) tire portions with which the various profilometers are associated in order to be able to scan the entire tire, c) tire portions scanned by the RGB color cameras;

(6) FIG. 5—a 3D reconstruction, after scanning, of the outer shoulder of a tire;

(7) FIG. 6—a 3D reconstruction, after scanning of the outer surface of the tread of a tire in which an abrasion defect is present;

(8) FIG. 7—a 3D reconstruction, after scanning, of the tire surface in FIG. 6 and of the position of the single points which compose it;

(9) FIG. 8—a 3D reconstruction, after scanning, of the section of the outer shoulder of the reference tire sample;

(10) FIG. 9—a 3D reconstruction, after scanning, of the section of the outer shoulder corresponding to that in FIG. 8 of a sample of tire to be tested which has a defect in the highlighted portion;

(11) FIGS. 10, 11, 12, 13—some structural and surface defects which may occur on the tires;

(12) FIGS. 14, 15, 16—some color defects which may occur on the tread of the tires, relative to barcodes, lettering and reference commercial codes.

(13) A key of the numeric references used follows for the sake of clarity: 1 profilometer for scanning the outer surface of the tread 2 profilometer for scanning of the outer surface of a shoulder and, after overturning of the tire, of the other one, 3 profilometer for scanning the inner surface of the tread 4 profilometer for scanning of the inner surface of a shoulder and, after overturning of the tire, of the other one, 5 profilometer for scanning the rim-tire coupling bead portion 6 tread profilometer ratio motor on Z axis 7 tread profilometer on Z axis 8 outer shoulder profilometer ratio motor on Z axis 9 outer shoulder profilometer on Z axis 10 outer profilometer ratio motors on X axis 11 outer profilometer on X axis 12 inner shoulder profilometer on Z axis 13 inner profilometer on Z axis 14 inner profilometer ratio motor on Z axis 15 inner profilometer on X axis 16 inner profilometer ratio motor on X axis 17 rotating table 18 rotating table ratio motor 19 workbench 20 inner profilometer swift on axis X-Z 21 tire 1. outer surface of the shoulder 2. inner surface of the shoulder 3. outer surface of the tread 4. inner surface of the tread 5. tire-rim coupling bead portion 22 RGB color camera for detecting the outer surface of the tread 23 RGB color camera for detecting the outer surface of the outer side shoulder and, after overturning of the tire, of the other one.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(14) With reference to said figures is provided in the following the description of some example embodiments of an apparatus for detecting the defects of a tire 21 at the end of the production process provided with the following main elements: a workbench 19, including a rotating table 17, for supporting and moving the tire 21 to test, profilometer means 1, 2, 3, 4, 5, for scanning the surface of various sections of tire and for detecting the profiles, provided with devices adapted to project a laser line on the surface to be measured and continuously acquire the profile drawn from light by means of linear camera, high-resolution RGB color linear camera means 22, 23, for scanning the outer portions of the tire, tread and shoulders, and creating color images, mechanical means 7, 9, 11, 12, 13, 15, 20 for supporting and moving said scanning assemblies (profilometers and RGB color cameras), means 6, 8, 10, 14, 16, 18 respectively electromechanical automation means (motors, brushless, sensors) and electronic devices means (PLC, inverter, drive brushless motors and controlled axes) for managing and operating said electromechanical automation means, computer mean provided with suitable software for processing the data coming from the profilometers and from the RGB color cameras, creating a 3D model and color model of the tire under test, and managing a database related to all features of the manufactured tires, both those of the automation setting and those of models for analyzing 3D and color defects, operator interface, installed aboard the computer, for the interaction between production operator and the apparatus.

(15) The scans performed simultaneously by the profilometers and by the RGB cameras are obtained by turning at controlled speed the rotating table 17 on which the tire 21 is placed, while the detection, characterization and classification of one or more defects are performed univocally by the software by means of algorithmic comparison between the detection zone of the tire sample to test, which is scanned, and the corresponding one of the defect-free reference tire sample.

(16) The apparatus according to the present invention, shown in some layout respectively with a single test station (FIG. 1), with two stations (FIGS. 2 and 3), enables to check and detect the defects of the tires by means of laser profilometry technology for the acquiring the individual profiles of the surfaces to test.

(17) The laser profilometers 1, 2, 3, 4, 5, use triangulation method in order to detect the profile of the surfaces and perform measurements on the surfaces themselves.

(18) The technique is to project a laser line on the surface to be measured and to continuously acquire, by means of a linear camera positioned at an angle of 25-45° with respect to the laser, the profile drawn by the light and thereby recording the dimensions along the two axes X and Z.

(19) In order to obtain the 3D image, the laser device performs a relative movement also along the Y axis, whereby continuously acquiring the profiles shown by the camera; said movement is obtained by rotating at controlled speed the table 17 on which the tire is placed.

(20) A software, specifically developed for the application, performs the assembly of the single profiles acquired along the Y axis and thus allows the 3D reconstruction of the scanned surface.

(21) Each profilometer is provided with linear camera and independent laser, with the technical features required for the section of the tire to be analyzed (acquisition speed of the camera, resolution, optics, filters, laser power, distances between the laser and camera, framed portions, etc.).

(22) The apparatus requires the use of hi-tech products, selected on the market as a function of the required features and their application and integration in the system.

(23) The reconstruction of the three-dimensional image of the single surface is obtained starting from the primitive function obtained by means of the cameras in form of software data, or clouds of points in space of the single profiles; said primitive function are integrated in a high-level software which creates the 3D model of the entire scanned surface (tread, shoulder, bead portion).

(24) As shown in FIG. 4, a suitably dimensioned laser unit-camera is installed for each of the surfaces which form the tire, inner surface 21.4 and outer surface 21.3 of the tread, inner surface 21.2 and outer surface 21.1 of the shoulder, rim-tire coupling bead portion surface 21.5, for a total of five, each of which provides the 3D image of the surface associated with it.

(25) All acquired images, obtained by creating a relative movement between tire and laser-camera system, are processed to obtain the 3D model of the complete tire that will be processed by the defect processing software installed on the apparatus.

(26) For analyzing the defects of specific and small size portions of tire, or for small size tires, such as for example tires for motorcycles, which require less stringent technical features than those of standard products available on the market, the apparatus according to the present invention uses, for some sections of the tire, standard profilometers instead of the laser unit-camera, integrating them in the apparatus as smart sensors.

(27) Each profilometer acquires therefore in sequence the profiles of the section of the rotating tire, constituted by clouds of points in space, with which it is associated (tread, shoulder, etc.).

(28) These profiles, 8,000-12,000 profiles per tire, are stored by the processing computer.

(29) The three-dimensional image of the surface of the tire to test, see FIG. 5, obtained by using the software of the apparatus, starting from the software primitive function of the cameras, contains the X-Y-Z coordinates for each point in the space of the tire itself; for example, the tread shown in FIG. 6 containing an abrasion defect, shows the X-Y-Z coordinates of each point in the 3D reconstruction of the same section, see FIG. 7.

(30) For each commercial code of the tires manufactured in a plant, a model is created starting from a defect-free reference tire sample: all tire surfaces are scanned to create the model.

(31) During this step, the model creation software requires the presence of the production engineer who, by means of the user-friendly interface with which the apparatus is equipped, interacts with the system to select the portions for defining the parameters of acceptability of the tire in all its portions and for setting the parameters of each defect.

(32) At the end of the creation step of the 3D model, it is stored in the database, matching it with the commercial code of the tire.

(33) During the production step, the tire is tested by automatic scanning, reconstructing the 3D image and comparing the areas and portions of the tire with the corresponding default 3D model.

(34) The portions on which are found differences with respect to those of the default model are subjected to a successive analysis for identifying the defect: the processing is performed specifically for each classified portion in which the defect is present, according to parameters set during the model creation step.

(35) FIGS. 8 and 9 show two 3D images obtained after scanning the section of the outer shoulder of a tire: the first is the one related to the section of the shoulder of the model of the reference tire sample and the second is the same section of the tire to test, which has a defect in the highlighted portion on the inside of the rim; as can be seen, the two images are identical with the exception of the defect present inside the highlighted circle.

(36) The apparatus according to the present invention also allows analyzing color defects, which are very important because tire manufacturers use color for different purposes during the production step.

(37) These defects are identified by using high-resolution linear RGB color cameras present in the apparatus, which scan the outer portions of the tire tread and shoulders, and create the color images of the portions. By analyzing the images, as a function of color images previously stored of the same tire model, it is possible to examine the dissimilarities of the tire to test against the reference sample and to determine the defects arising from color differences on the tire surfaces.

(38) The steps that the apparatus automatically performs during the entire defect examination time are illustrated: a. picking the tire to test from the production line and positioning the same on the rotating table of the apparatus; the tire is picked by a robot, or specific machine, which guarantees the centering of tire on the rotating table of the apparatus; b. starting the automatic positioning, as a function of the tire type, of the moveable equipment of the profilometers and of the RGB color cameras mounted on controlled axes; c. start rotating the rotating table on which the tire is placed to perform a 360° full scan and at the same time to acquire the profiles and color defects along the entire circumference, inside and outside, of the tire (tread outer surface, shoulder outer surface, tread inner surface, other shoulder inner surface, rim-tire coupling bead portion); d. processing the acquired profiles, 3D reconstruction of the surfaces and reconstruction of the images acquired by the RGB cameras; e. detecting one or more defects, by comparing the tire sample to test, already scanned, and a corresponding defect-free reference tire sample (of the same model/type); the defect is detected by means of algorithmic comparison between the detection portion of the tire to test and the corresponding one of the reference sample; sophisticated algorithms enables to univocally identify, characterize and classify any defect (type, shape, size, color, etc.); f. stopping and repositioning in the starting conditions said profilometer means and said RGB cameras; g. automatic overturning of the tire and positioning it on the same rotating table to allow the apparatus to scan the remaining surfaces of the tire, previously not available; h. repeating steps b, c, d, e, f; i. final picking of the tire at the end of the test operations and repositioning the same on the production line depending on the result of the test defect; the picking of tire is performed by a robot, or a specific machine.

(39) The cycle described above relates to the single test station apparatus (illustrated in FIG. 1) provided with a single rotating table on which the scanning of the tread, inner and outer surface, of an outer shoulder and, after overturning of the tire, also of the other one, of an inner shoulder and, after overturning of the tire, also of the other one and of the rim-tire coupling bead portion.

(40) The cycle time required for analyzing a tire according to said process is about 60 seconds.

(41) When short cycle times defect analysis is required, the apparatus is equipped with two stations (FIGS. 2 and 3), which are mechanically perfectly identical and each equipped with the profilometers and RGB cameras needed for scanning the assigned surfaces.

(42) The operation and the defect scanning and analysis software is perfectly equal to the one installed on the single station apparatus, and the stations are duplicated only to allow scanning two tires at the same time, with an evident reduction of the cycle time, enabling to obtain cycle times of about 40 seconds for each tire during a complete test.

(43) FIGS. 10, 11, 12, 13 show, as an example, some structural and surface defects which may appear on the tires; three images are associated with each defect: photo of the tire: a photo of a tire section with a defect, 3D reconstruction: 3D image reconstruction of the tire section where the defect is located, processing results: the identified defect with indication of position and size.

(44) FIGS. 14, 15, 16 show, as an example, some defects that may appear on the tread of a tire relative to the barcodes, lettering and commercial reference codes: incorrect positioning of lines (FIG. 14), distorted letters (FIG. 15), incorrect lettering positioning (FIG. 16).

(45) The apparatus and the method according to the present invention allow the following improvements compared to current technologies: a full analysis of the inner and outer sections of the tire, by scanning using laser profilometers and RGB cameras (scanning of each part of the tire, even the most hidden); the automatic positioning, as a function of the tire type, of moveable equipment of the profilometers and inner and outer RBG cameras; matching of dual optical detection technology by means of laser and RGB cameras; detecting, 3D modeling and classification of each surface and color defect by matching said technologies.

(46) Inserting an automatic defect examination station in the production line, replacing the manual station with operator (three specialized operators on three work shifts), also makes it possible: to obtain a considerable yearly saving, in addition to the obvious advantages of result objectivity and of guaranteed analysis times, to automate the quality examination process of tires at end of the production line which today is particularly expensive and critical, particularly in certain geographical areas in which the operators are not particularly skilled or trained, to solve quality problems by reducing the possibility marketing products with defects not detected manually by the operator.

(47) The cycle time of the method is 40-60 seconds for each tire to test; said time is perfectly comparable to the time currently employed by a qualified operator, but guaranteeing higher efficiency because it is a fully automatic apparatus having much greater result repeatability and guarantee than that of a single operator.

(48) The defect detection apparatus according to the present invention, shown in some preferred embodiments, is modular and is susceptible to numerous modifications and variants according to manufacturing demands, the operating principle remaining unchanged. In some manufacturing processes, it could be necessary, for example, to vary the number and the position of the detection devices (profilometers and RGB cameras) or in other cases the presence of some of them or not.

(49) Indeed, the need may arise that the detection of color defects of the tires is not needed, or the installation of RGB cameras for detecting color defects inside the tire is needed (defects due to contamination of the rubber or escape of steam from the balloon of the vulcanization press).

(50) Another possibility could be given by the need to provide the apparatus with a specific external profilometer for detecting surfaces of special tires which require a more detailed defect analysis, for example for the manufacturing of low-profile tires, in which the size of the shoulder is much lower or other tires with special profiles, also subject to new design.

(51) For the production of tires of particular manufacturers, it could be necessary to insert profilometers and/or additional axes in the apparatus in order to be able to scan specific parts of the tire.

(52) The apparatus performs the 3D reconstruction of all surfaces of a tire, also of the surfaces of the shoulders on which reference letters and commercial codes are printed; this is necessary in cases in which said codes are not supplied by the production line before setting the apparatus.

(53) For recognizing said lettering and codes, the apparatus is equipped with specific software, which uses OCR (Optical Character Recognition) algorithms.

(54) By means of the apparatus, it is possible to detect any type of defect present on a tire with variable shape, color, size.

(55) The apparatus according to the present invention is also applied to maintenance checks and examinations of the state of tires outside the production process.

(56) The object of the invention is susceptible to many changes and variations, all falling within the inventive concept expressed in the attached claims.

(57) All parts may be replaced with other technically equivalent elements, and the materials may be different according to needs, without departing from the scope of protection of the present invention.

(58) Although the object was described with particular reference to the attached figures, the reference numbers used in the description and in the claims are used for a better understanding of the invention and do not constitute any limitation to the disclosed scope of protection.