Method of installing vent valves in a tire mold lining

Abstract

The present invention relates to a method for installing vent valves (24) in a trim sector (9) of a tire mold, the method comprising the following steps: - fixing the sector (9) to a support (10), - acquiring images of the sector (9) from different viewing angles of the sector (9), the acquisition being carried out in an acquisition station (3), - generating a three-dimensional map of the sector (9) from the images, - identifying in the sector (9) orifices for vent valves (24) using the map, the identification of the orifices comprising a referencing of the position of the orifices relative to the support (10), - moving the support (10) to a laying station (16) different from the acquisition station (3), and - installing in each orifice a vent valve (24), the installation being carried out in the laying station (16). Figure for abstract: figure 1

Description

Title of the invention: Method for installing vent valves in a tire mold lining FIELD OF THE INVENTION

[0001] The invention relates to a method for installing vent valves in a tire mold lining, and in particular an automatic installation method. STATE OF THE ART

[0002] Before molding a tire, it is necessary to install vent valves in the linings included in the mold. The vent valves allow air to be expelled from the mold when the tire material is inserted into the mold. When the vent valves are installed by hand, the operator must perform meticulous, time-consuming and ergonomically undesirable work, particularly because of the posture he must adopt and the repetitive nature of the task.

[0003] There is a need to develop a method of installing a vent valve that reduces the arduousness of manual tasks. Statement of the invention

[0004] An aim of the present disclosure is to provide a method of installing a vent valve which reduces the arduousness of manual tasks compared to the prior art.

[0005] The aim is achieved by a method of installing vent valves in a lining sector of a tire mold, the method comprising the following steps:

[0006] - fixing the sector to a fixing support,

[0007] - acquisition of images of the sector according to different viewing angles of the sector, the acquisition being carried out in an acquisition position,

[0008] - generation of a three-dimensional map of the sector from the images,

[0009] - identification in the sector of orifices for vent valves using the mapping, identification of orifices including referencing of a position of the orifices relative to the support,

[0010] - moving the support to a placement station different from the acquisition station, and

[0011] - installation in each orifice of a vent valve, the installation being carried out in the installation station.

[0012] Such a method is advantageously and optionally supplemented by the following different characteristics taken alone or in combination: - a step of determining for each orifice the orientation of the orifice, the installation of the vent valve taking into account the orientation of the orifice; - the identification of the orifices includes a step of detecting a cylindrical shape in the mapping; - the determination for each orifice of a diameter of the orifice includes a step of adjusting the cylindrical shape so that the cylindrical shape passes through a maximum number of points of the mapping; - the identification step in the sector of orifices for vent valves comprises determining for each orifice a diameter of the orifice, the method comprising a step of determining for each orifice a size of vent valves adapted to the orifice, the valve size being part of a set of valve sizes, the installation step being configured to install in each orifice a vent valve having the size adapted to the orifice; - a step of transmitting data from the acquisition station to the installation station; - a step of checking the installation of the valves; and - the image acquisition step comprises several rotations of the sector relative to a photographic device, a number of rotations being greater than or equal to four.

[0013] The disclosure also relates to a device for installing vent valves in a lining sector of a tire mold, the device comprising:

[0014] - a support for fixing the trim sector,

[0015] - an acquisition station comprising a photographic device,

[0016] - a conveyor configured to set the sector in motion relative to the camera,

[0017] - a processor configured to generate a three-dimensional map of the sector from images of the sector, to identify vent valve ports in the sector using mapping,

[0018] - a laying station comprising a device controlled for laying in each orifice a vent valve, and

[0019] - a conveyor configured to move the medium from the acquisition station to the installation station. DESCRIPTION OF FIGURES

[0020] Other characteristics and advantages will emerge from the following description, which is purely illustrative and non-limiting, and must be read in conjunction with the attached drawings in which:

[0021] [Fig.l] [Fig.l] is a schematic representation of an example of a device for installing vent valves; and

[0022] [Fig.2] [Fig.2] is a schematic representation of an example of a method of installation of vent valves. DETAILED DESCRIPTION OF THE INVENTION

[0023] A tire mold has a central axis that corresponds to the axis of the tire that is to be produced. The mold comprises mold sectors distributed angularly around the axis. Each sector corresponds to an angular sector of the mold, typically of 25 degrees of angle. The mold sectors correspond to the outer parts of the mold. During the molding process, the mold sectors are assembled and mechanically mounted against each other to form the mold.

[0024] Within each sector, the mold comprises a lining sector. It is the lining sector that is in contact with the tire material, for example rubber, during molding. It is the lining sector that provides the relief of the tire tread. A lining sector comprises a rear face that is intended to be in contact with the mold sector and a front face that is intended to be in contact with the tire material during molding.

[0025] The different lining sectors are, like the different mold sectors, distributed angularly around the axis. Each lining sector typically extends over 25 degrees of angle and the assembly of the different lining sectors composes the lining of the mold. There are different types of lining, including winter tire lining and summer tire lining.

[0026] Each lining sector is pierced with orifices. Each orifice has a cylindrical shape with a circular cross-section. Each orifice passes right through the sector in a direction of extension which is radial or almost radial. Advantageously, the direction of extension of the orifice is orthogonal to a local curvature of the inner relief of the lining. The inner relief of the lining is the part of the lining which gives the relief of the tire tread.

[0027] Each orifice is characterized by a diameter, a position in the trim sector and an orientation relative to the trim sector.

[0028] The orifice is intended to accommodate a vent valve.

[0029] In a trim sector, the orifices do not necessarily all have the same size, because the sector may be intended to receive valves of different sizes. There is then a set of valve sizes that are different from each other. For example, the trim sector may receive a first type of vent valves that have a diameter of 2.5 mm and a second type of vent valves that have a diameter of 3 mm. Alternatively, the set of valve sizes comprises a first length of a first type of valve and a second length of a second type of valve, the first type of valve and the second type of valve having the same diameter. The diameter of the valve is measured in a transverse plane of the valve. A vent valve has a length or height that is typically 10 mm. The length or height of the valve is measured in a longitudinal direction. The longitudinal direction is orthogonal to the transverse plane.

[0030] When the vent valve is inserted into the orifice, the longitudinal direction of the valve corresponds to the extension direction of the orifice.

[0031] In relation to [Fig.l], a device 1 for installing vent valves comprises an acquisition station 3. The acquisition station 3 comprises a photographic apparatus 5. The photographic apparatus may in particular be a three-dimensional camera known as a 3D camera.

[0032] The photographic apparatus 5 is connected to a processor 14. The processor 14 is in particular configured to control the shooting parameters of the photographic apparatus and trigger the image capture. The processor 14 is configured to carry out a processing of the images produced by the photographic apparatus 5. In particular, the processor 14 is configured to generate, from a plurality of images of an object, a three-dimensional map of the object. A three-dimensional map is a modeling of the relief of the object. For a mesh of the surface of the object, that is to say for a plurality of points regularly distributed on the surface of the object, the positions in space of these different points are measured in a study reference frame defined by an origin point and three axes forming an orthonormal base. All of the coordinates of the points measured relative to the study reference frame gives the three-dimensional map.This generation of mapping can notably be based on a photogrammetry technique.

[0033] The processor 14 is also configured to identify and characterize particular shapes in a three-dimensional map. Among the particular shapes, the processor 14 is configured to identify and characterize cylindrical shapes with a circular section. In other words, the processor can use: - a method of traversing or scanning the map to detect an area of the map which has a cylindrical shape with a circular section, and - an adjustment method applied to the area to determine the cylindrical shape parameters of the area, typically a diameter and a length; this adjustment may in particular correspond to searching for a virtual cylinder which passes through as many points as possible in the area of the map, so that the cylindrical shape passes through a maximum number of points of the map.

[0034] The camera 5 is mounted on a mechanical actuator 7 or automatic arm 7. The mechanical actuator 7 makes it possible to move and orient the camera- topographic 5.

[0035] The acquisition station 3 comprises a base 12 configured to receive a trim sector 9. The trim sector 9 can be placed so that the rear face of the sector is located between the base 12 and the front face of the sector. The front face of the sector is directed outwards, it does not face the base 12.

[0036] The base 12 may have degrees of freedom, in particular in rotation, to move and orient the trim sector 9 relative to the photographic apparatus 5. The base 12 comprises a conveyor configured to set the trim sector 9 in motion relative to the photographic apparatus, in particular to set it in rotational motion.

[0037] In particular, the base 12 can be controlled in rotation around a vertical axis Z. The base 12 is for example connected to the processor 14 so that the position of the base 12 in rotation can be controlled from the processor 14.

[0038] Advantageously, the trim sector 9 is fixed to the base 12 via a support 10. The support 10, which is a support for fixing the trim sector 9, can then serve as a spatial reference for the trim sector. The fixing of the trim sector 9 on the support 10 can be precise to the nearest micron. The support 10 can have one or more markers which make it possible to spatially reference the support 10 in the reference frame of the acquisition station or subsequently in another station.

[0039] Still in relation to [Fig.l], the device 1 for installing vent valves comprises a installing station 16. The installing station 16 is different from the acquisition station 3. The device 1 comprises a conveyor configured to move the packing sector 9 from the acquisition station to the installing station. Advantageously, the conveyor is configured to move the packing sector 9 fixed on its support from the acquisition station to the installing station. The installing station 16 comprises a valve installing head 18. The installing head 18 is configured to place a valve 24 inside an orifice of the packing sector 9. The installing head 18 is connected to a reservoir 20 of valve 24 by a conduit 22. The installing head has a installing axis which is the axis along which the head moves the vent valve. During this movement, the installing axis corresponds to the longitudinal direction of the valve.

[0040] The laying head 18 is attached to a mechanical actuator or articulated arm 26 which is configured to move and orient the laying head 18.

[0041] The installation station 16 comprises a base 28 configured to fix the trim sector 9 during the installation of the valves. The base 28 comprises one or more degrees of freedom for moving and orienting the trim sector 9.

[0042] When the installation station 16 and the acquisition station 3 merge into a single station, the base 28 corresponds to the base 12.

[0043] The laying station 16 comprises a control unit 30 which is configured to control the position and orientation of the installation head 18 and the base 28.

[0044] The processor 14 is connected to the installation station 16 and in particular to the control unit 30 to transmit data and in particular a three-dimensional map.

[0045] A device for installing a vent valve as just presented makes it possible to implement a method P for installing a vent valve which is now explained and which is illustrated schematically in [Fig.2].

[0046] During a first step SI, the trim sector 9 is fixed to the reference support 10. This first step SI is optional. In particular, when the acquisition station 3 and the installation station 16 form a single station, it is not essential to carry out this step SI.

[0047] During a second step S2, the photographic apparatus 5 takes a plurality of images of the trim sector 9. In particular, these images are images of the front face of the trim sector 9. The second step S2 is carried out in the acquisition station.

[0048] Advantageously, the camera is placed at a distance of approximately 400 mm from the center of the front face of the trim sector 9. This distance may be greater than or equal to 300 mm and less than or equal to 500 mm. The camera has an optical axis. The camera is oriented so that its optical axis passes through the trim sector 9 and ideally the center of the front face of the trim sector 9. The camera is oriented so that its optical axis has a non-zero angle relative to a horizontal plane. The angle is greater than or equal to 25° and less than or equal to 75°. For example, the angle is 45° or 50°.

[0049] The images are acquired during step S2 from different viewing angles. In particular, it is possible to rotate the trim sector 9 around a vertical axis passing through the trim sector 9 between two image acquisitions. In an equivalent manner, the camera can be rotated around this axis between two image acquisitions.

[0050] For example, four photographs can be acquired and a 90° angle rotation of the trim sector 9 around the vertical axis can be performed between two acquisitions. Alternatively, five photographs can be acquired and a 72° angle rotation of the trim sector 9 around the vertical axis can be performed between two acquisitions. More generally, a number n of photographs can be acquired and a (360 / n)° angle rotation of the trim sector 9 around the vertical axis can be performed between two acquisitions.

[0051] During a third step S3, the processor 14 generates a three-dimensional map of the trim sector 9 from the images acquired during the second step S2.

[0052] During a fourth step S4, the processor 14 identifies in the trim sector 9 one or more orifices for vent valves using the mapping. The processor can in particular implement: - the above-mentioned mapping or scanning method to identify cylindrical shapes in the trim area, and - the above-mentioned adjustment method to determine a measurement of the diameter of the identified cylindrical shape(s).

[0053] During step S4, the processor 14 identifies one or more orifices in the trim sector and for each orifice determines a position of the orifice. When the trim sector 9 is fixed to the reference support 10, the identification of the orifices can advantageously comprise a referencing of the position of the orifices relative to the support 10. The support 10 then serves as a spatial reference for the trim sector 9 and it is possible to use in the installation station 16 all the geometric characterization of the trim sector 9 carried out during steps S4, S5 and S6 in the acquisition station 3. The information concerning the position, orientation, diameter and type of valve associated with each orifice is transmitted to the installation station 16, and in particular the control unit 30.

[0054] Optionally, the processor 14 determines for each orifice a diameter of the orifice.

[0055] During a fifth step S5, the processor 14 can determine an orientation of the orifice which is given by the orientation of the axis of the cylinder relative to the base of the three-dimensional map.

[0056] During a sixth step S6, the processor 14 associates with each identified orifice a type of valve to be installed in the orifice. When all the valves to be installed have the same dimensions, and in particular the same diameter, the processor 14 always associates the same type of valve to be installed. On the other hand, if the orifices to be installed do not all have the same size, and if there is a set of valve sizes that are different from one another, then the association made by the processor 14 is based in particular on the diameter of the orifice determined during the fourth step S4. For an identified orifice, the determined diameter is compared to the different sizes of valves that are intended to be installed in the trim sector, that is to say to candidate diameters for example 2.5 mm and 3 mm as mentioned above.When the difference between the determined diameter and one of the candidate diameters is less than or equal to a threshold, then the orifice is associated with the corresponding valve type. When for each of the candidate diameters, the difference between the determined diameter and the candidate diameter is greater than the threshold, then the orifice is not taken into account for the subsequent steps of the process.

[0057] During an optional seventh step S7, the trim sector 9 is moved from the acquisition station 3 to the installation station 16. This step is not necessary when these two stations form a single station. When this seventh step S7 is implemented, it is advantageous for the trim sector 9 to be fixed to a reference support 10. The support 10 can then serve as a spatial reference for the trim sector 9 and it is possible to use in the installation station 16 all the geometric characterization of the trim sector 9 carried out during steps S4, S5 and S6 in the acquisition station 3. The information concerning the position, orientation, diameter and type of valve associated with each orifice is transmitted to the installation station 16, and in particular the control unit 30.

[0058] During an eighth step S8, vent valves are placed in the orifices. Step S8 is carried out in the installation station.

[0059] As previously, a diameter and a suitable size of vent valves are determined for each orifice; it is possible in step S8 to fill the orifices with several types of valves, and in particular valves of different diameters.

[0060] For each orifice identified and associated with a type of valve, the position and type of valve that must be installed there are known. This simplifies the installation process. This is particularly the case when an operator carries out this installation. Manual work time is reduced, since there is no hesitation about the type of valve to choose depending on the orifice.

[0061] Alternatively, the installation can be carried out by the installation head 18. In this case, it is an installation in each orifice of a vent valve by means of an automated module which is carried out. The use of the automated module, namely the installation head 18, makes it possible not to carry out the installation of the vent valves by hand. Manual tasks and the arduousness thereof are eliminated.

[0062] The method can be implemented for any type of lining, and in particular winter tire lining and summer tire lining. The method can in particular be applied to certain lining sectors which comprise lining sub-sectors. These sub-sectors can be handled in batches and laid flat against each other to carry out the installation of the valves. The shape of the lining sector during this installation is then not the shape of the lining sector during molding. There is a subsequent step of adjusting the shape of the lining sector during the assembly of the mold.

[0063] Furthermore, thanks to this method, it is not necessary to have a 3D CAD (three-dimensional computer-aided design) model of the trim sector in order to install valves in all the orifices of the sector.

[0064] For each orifice to be filled, the control unit 30 controls on the one hand the mechanical actuator or articulated arm 26 which moves and orients the laying head 18 and on the other hand the base 28 which moves and orients the trim section 9 so that the installation head 18 is located opposite the orifice to be filled. The installation head 18 is loaded with a vent valve 24 coming from the reservoir 20. The installation head 18 inserts the vent valve 24 inside the orifice to be filled over a controlled length.

[0065] For each orifice identified and associated with a type of valve, the position and type of valve that must be placed there are known. For each orifice to be filled, the control unit 30 controls on the one hand the mechanical actuator or articulated arm 26 which moves and orients the installation head 18 and on the other hand the base 28 which moves and orients the lining sector 9 so that the installation head 18 is located opposite the orifice to be filled. The installation head 18 is loaded with a vent valve 24 coming from the reservoir 20. The installation head 18 inserts the vent valve 24 inside the orifice to be filled over a controlled length.

[0066] When the processor 14 has determined the orientation of the orifice during step S5, this is taken into account during the eighth step S8. For each orifice to be filled, the control unit 30 controls on the one hand the mechanical actuator or articulated arm 26 which moves and orients the laying head 18 and on the other hand the base 28 which moves and orients the trim sector 9 so that the axis of the laying head 18 is aligned with the direction of extension of the axis of the orifice to be filled. Determining the orientation of the orifice relative to the sector then makes it possible to carry out more precise automated laying of the valve.

[0067] If step S1 has taken place, the trim sector 9 is fixed to the reference support 10. This makes it possible to stabilize and move the trim sector in a controlled manner during step S8. In particular, it is possible to control the movement of the support and therefore of the sector during rotations before image acquisition or to control the movement of the support during the installation of the vent valves. This makes it possible to carry out these operations in a more stable manner and to obtain better performance.

[0068] When all of the orifices to be filled are filled with a valve of suitable size, step S8 ends.

[0069] It should be noted that the use of a reference support, since it makes it possible to reference the positions and orientations of the orifices of the sector relative to the support, makes it possible to carry out the acquisition in the acquisition station, then the installation in the installation station different from the acquisition station while retaining the benefit of the measurements. This makes it possible to increase the production rate of the trim sectors whose orifices are fitted with a valve; it is in fact possible to simultaneously carry out a valve installation on a trim sector in the acquisition station and an acquisition of the geometric data on another trim sector in the acquisition station.

[0070] During an optional ninth step S9, the installation of the valves can be checked.

[0071] This step S9 can be carried out by an operator.

[0072] Alternatively, this step S9 can be implemented by performing steps S2, S3 and S4 on the trim sector 9 once it has been filled with the vent valves. If all the orifices have been filled with a valve, a new detection of orifices in the map does not give any new orifice detected.

[0073] Another way of implementing step S9 is to carry out steps S2 and S3 and then to check the geometry of the lining sector 9 at each orifice filled during step S8. By comparing the new mapping and the previous mapping, it is possible to check for each orifice whether a valve has been inserted and if so to what depth.

[0074] For these last two methods, and since the acquisition station is different from the installation station, this step S9 involves moving the trim sector from the installation station 16 to the acquisition station 3.

Claims

Claims

1. A method of installing vent valves (24) in a trim sector (9) of a tire mold, the method comprising the following steps: - (S1) fixing the sector (9) to a fixing support (10), - (S2) acquiring images of the sector (9) from different viewing angles of the sector (9), the acquisition being carried out in an acquisition station (3), - (S3) generating a three-dimensional map of the sector (9) from the images, - (S4) identifying in the sector (9) orifices for vent valves (24) using the map, the identification of the orifices comprising referencing a position of the orifices relative to the support (10), - (S7) moving the support (10) to a installing station (16) different from the acquisition station (3), and - (S8) installing in each orifice a vent valve (24), the installation being carried out in the installation station (16).

2. Method according to claim 1 further comprising a step (S5) of determining for each orifice the orientation of the orifice, the installation of the vent valve taking into account the orientation of the orifice.

3. A method according to any one of claims 1 or 2 wherein the identification of the orifices comprises a step of detecting a cylindrical shape in the mapping.

4. A method according to claim 3 wherein determining for each orifice a diameter of the orifice comprises a step of adjusting the cylindrical shape so that the cylindrical shape passes through a maximum number of points of the mapping.

5. Method according to any one of claims 1 to 4 in which the step (S4) of identifying in the sector orifices for vent valves comprises determining for each orifice a diameter of the orifice, the method comprising a step (S6) of determining for each orifice a size of vent valves adapted to the orifice, the valve size being part of a set of valve sizes, the step (S8) of laying being configured to lay in each orifice a vent valve having the size adapted to the orifice.

6. Method according to claim 5 comprising a step of transmitting data from the acquisition station (3) to the installation station (16).

7. Method according to any one of claims 1 to 6 comprising a step (S9) of verifying the installation of the valves.

8. Method according to any one of claims 1 to 7 wherein the step (S2) of acquiring images comprises several rotations of the sector relative to a photographic apparatus (5), a number of rotations being greater than or equal to four.

9. Device (1) for installing vent valves (24) in a lining sector (9) of a tire mold, the device (1) comprising: - a support (10) for fixing the lining sector (9), - an acquisition station (3) comprising a camera (5), - a base (12) configured to receive the lining sector (9) and to set the lining sector (9) in motion relative to the camera, - a processor (14) configured to generate a three-dimensional map of the sector from images of the sector, to identify in the sector orifices for vent valves using the map, - an installation station (16) comprising a controlled apparatus for installing in each orifice a vent valve, and - a conveyor configured to move the support from the acquisition station to the installation station.

Images