A method of centring raw tyre materials on an assembly line conveyor, and a device for performing the method

Abstract

The present invention relates to a method for centring raw tyre materials on a conveyor of an assembly line comprising a first conveyor, a loading conveyor, and a carcass drum or a bumper drum, characterised in that it comprises detecting the position of a raw tyre materials on the basis of the presence of the left edge of the material in the field of view of a left camera sensor (1) and the right edge of the material in the field of view of a right camera sensor (2), comprising the steps of: detecting the presence of edges of the material placed on the loading conveyor during movement of the loading conveyor by the right camera sensor (2) and the left camera sensor (1) by periodically scanning the edge of the material along the entire length of the material (3), wherein each cycle comprises: (a) sending a signal to a control system (7), if the right edge and the left edge are present, that a measurement of the position of the axis of the material (3) is being initiated; (b) detecting the position of the edge of the material to the right and / or to the left with respect to the axis of the field of view of the camera sensor (1), (2); (c) determining the deviation a from the axis of the field of view of the left camera sensor (1) and determining the deviation b from the axis of the field of view of the right camera sensor (2); if the deviation a to the left of the axis of the field of view a* = -a, if the deviation a to the right of the axis of the field of view a* = a; if the deviation b to the left of the axis of the field of view b* = -b, if the deviation b to the right of the axis of the field of view b* = b; (d) determining the current position of the axis of the material (3) - a data [x], according to the formula x=(a*+ b*) / 2; (e) sending the data [x] to the control system (7), which assigns a data [y] to the data [x] about the current position of the loading conveyor sensed by the control system using the encoder (8), to form a two-dimensional number [x,y], which carries information about the axial offset of the material (3) with respect to the central axis of the drum in the radial direction, and the position where this axial offset is located on the loading conveyor; (f) storing the two-dimensional number [x,y] in the cache memory of the control system (7); and compensating for the axial offset of the material (3) relative to the drum when winding the material onto the drum, wherein the control system (7) moves the loading conveyor by means of an actuator (9) on the basis of the two-dimensional numbers [x,y] from the cache memory.

Description

[0001] A method of centring raw tyre materials on an assembly line conveyor, and a device for performing the method

[0002] Technical Field

[0003] The invention relates to a method for controlling the centring of raw tyre materials used in assembly lines prior to winding them onto an assembly drum, or bumpertread drum, hereinafter referred to as a centring unit.

[0004] Background Art

[0005] In the production of raw car tyres, rubber and composite materials are used, the main component of which is raw rubber. In the case of fully automated assembly lines, these are arranged in long reels on spools, which are part of so-called material cassettes. The reason for the use of material cassettes is their mobility, which ensures quick and convenient exchange of an empty material cassette for a full one. When winding raw tyre materials onto the spool of the cassette, the winding devices are not able to wind the materials without their slight undulation. In the process of unwinding materials in the assembly line, such undulation is partially or even completely eliminated by mechanical or electronic pre-centring equipment. Generally, there are several material preparation devices placed between each material cassette and the bumper-tread drum or assembly drum. Thus, each material has to travel a certain distance on the conveyor belt. These materials have sufficient shape memory to re-undulate to some extent on conveyor belts. This cannot be prevented by available means and it is therefore necessary to re-centre the materials directly before the winding process on the assembly drum in order to eliminate the undulation as much as possible. Any undulation of the material that is not removed prior to winding on the bumper-tread drum or carcass drum, but instead the material is wound undulated on the respective drum, significantly affects the quality of the final raw tyre. In some cases, this can affect the quality to such an extent that it produces a product unsuitable for further use. When centring raw tyre materials prior to winding them onto a carcass or bumper drum, specialised single-purpose centring equipment using specialised hardware and a closed-loop control system is commonly used for centring.

[0006] The objective of the present invention is to achieve centring of raw tyre materials in an efficient manner using standard off-the-shelf universal optical inspection components connected to an assembly line control system, so that it is not necessary to use specialized third-party centring systems to control the centring process.

[0007] Summary of the invention

[0008] A first aspect of the present invention is a method of centring raw tyre materials on a conveyor of an assembly line comprising a first conveyor, a loading conveyor, and a carcass drum or bumper drum, wherein the method comprises detecting the position of the raw tyre materials based on the presence of the left edge of the material in the field of view of the left camera sensor and the right edge of the material in the field of view of the right camera sensor, wherein the method comprises the following steps:

[0009] - detecting the presence of the edges of the material placed on the loading conveyor, during the movement of the loading conveyor, by the right camera sensor and by the left camera sensor by periodically scanning of the edge of the material along the entire length of the material, wherein each cycle consists of: a) sending a signal to a control system, if the right edge and left edge are present, that the measurement of the axis position of the material is being initiated; b) detecting the position of the edge of the material to the right and / or left with respect to the axis of the field of view of the camera sensor; c) determination of a deviation a from the axis of the field of view of the left camera sensor and determination of a deviation b from the axis of the field of view of the right camera sensor; if the deviation a is to the left of the axis of the field of view a* = -a, if the deviation a is to the right of the axis of the field of view a* = a; if the deviation b is to the left of the axis of the field of view b* = -b, if the deviation b is to the right of the axis of the field of view b* = b; d) determination of the current position of the axis of the material - a data [x] according to the formula x=(a*+ b*) / 2; e) sending the data [x] to the control system, which assigns a data [y] to the data [x] about the current position of the loading conveyor sensed by the control system using an encoder, to form a two- dimensional number [x,y], which carries information about the axial offset of the material with respect to the central axis of the drum in the radial direction and the position where this axial offset is located on the loading conveyor; f) storing the two-dimensional number [x, y] in the control system cache memory;

[0010] - compensation of the axial offset of the material with respect to the drum during material winding on the drum, wherein the control system moves the loading conveyor by means of an actuator on the basis of two- dimensional numbers [x,y] from the cache memory.

[0011] According to a preferred embodiment, the detecting of the position of the material according to the first aspect of the present invention occurs on the first conveyor. In other words, the presence of the material's edges is detected already on the first conveyor, and wherein a data [y] is an indication of the current position of the first conveyor, and wherein, when the material passes from the first conveyor to the loading conveyor, the data [y] is replaced by the data [y*] of the current position of the loading conveyor in two-dimensional numbers [x,y] stored in the cache memory to obtain the two-dimensional numbers [x, y*] of the position of the axial offset of the material on the loading conveyor, with a subsequent axial offset compensation of the material relative to the drum when the material is wound onto the drum, wherein the control system moves the loading conveyor using the actuator based on the two- dimensional numbers [x, y*] from the cache memory.

[0012] According to a preferred embodiment, the speed of movement of the first conveyor / loading conveyor is 100 to 500 mm / s, preferably 500 mm / s.

[0013] According to a preferred embodiment, the frame rate of both the right and left camera sensors is 60 to 200 Hz, preferably 200 Hz.

[0014] A second aspect of the present invention is a device for carrying out the method according to the present invention, wherein the device comprises: o an image sensing device comprising / consisting of a right camera sensor for sensing the right edge of the centred material and a left camera sensor for sensing the left edge of the centred material placed on the conveyor; o a unit for processing image signals from an image sensing device, wherein said unit is adapted to recognize left and right edges of the centred material from the image signals, to determine deviations a and b, to calculate the data [x] which is the current position of the axis of the material placed on the conveyor, and to send the data [x] to the control system of the assembly line; o at least one encoder for sensing the current position of the conveyor and possibly also of the loading conveyor; o an actuator to ensure the lateral movement of the loading conveyor; o the control system with cache memory adapted for actuator control and communication with the encoder.

[0015] Where the conveyor is understood to be a conveyor on which the position of the material is measured. The conveyor can be a first conveyor or a loading conveyor.

[0016] If the edge detection occurs on the first conveyor, the device according to the present invention includes two encoders, the 1stlocated on the first conveyor to obtain data [y] about the current position of the first conveyor and the 2ndlocated on the loading conveyor to obtain data [y*] about the current position of the loading conveyor.

[0017] If the edge detection occurs on the loading conveyor, the device includes one encoder, located on the loading conveyor, in order to obtain the data [y] about the current position of the loading conveyor.

[0018] The image sensing device shown in Figure 2 consists of two camera sensors 1 and 2 positioned so that the image sensing axis of the left camera sensor 1 is as close as possible to the left edge of the centred material 3 over the full range of widths of the raw tyre materials used, and the image sensing axis of the right camera sensor 2 is as close as possible to the right edge of the centred material 3 over the full range of widths of the raw tyre materials used. The material moves in direction 4.

[0019] The image signal processing unit recognizes the left and right edges of the material on the image signals of the left and right camera sensor and performs a position calculation of the material's axis according to the algorithm shown in Figure 3. The trace of the presence of the material edge and the start of the measurement of the material's axis position is sent via a communication bus to the control system of the assembly line as well as the data [x] of the current position of the material's axis, this current position of the material's axis is assigned in the control system to the data [y] of the current position of the conveyor of the respective centred material, thus a two-dimensional number [x, y] is formed. The two-dimensional number [x, y] carries information about the axial offset of the material with respect to the central axis of the respective bumper-tread or carcass drum in a radial direction and about the position where this axial offset is located on the conveyor. The number thus created is cached in the control system of the assembly line until the control system uses it to compensate for the axial offset of the wound material on the bumper-tread or assembly drum. The current position of the conveyor is sensed by the control system using an encoder. The time between measurement and compensation of the axial offset depends on the speed of material movement on the conveyor belt and the distance of the measured point from the assembly drum. For example, at a speed of 500 mm / s and a distance of the measuring point from the assembly drum of 3 m, this time is 6 s.

[0020] The whole process is repeated in the required increments of the conveyor's position until the edges of the respective centred material are no longer in the field of view of both camera sensors and the cache memory of numbers indicating the material's axial offset and the respective conveyor's position is completely filled.

[0021] After this process is completed, the material can be moved from the first conveyor to the loading conveyor, and the axial offset data of the material with the corresponding conveyor positions are converted to the loading conveyor's position so that when the material is transferred from the first conveyor to the loading conveyor, the control system extracts from the cache memory a two-dimensional number [x, y] corresponding to the point of the material that is currently passing from the first conveyor to the loading conveyor, then retrieves the data [y*] of the current position of the loading conveyor, and replaces the original data [y] of the current position of the first conveyor with the data [y*] of the current position of the loading conveyor in the two-dimensional number [x, y]. In this way, throughout the cache of two- dimensional numbers [x, y] indicating the axial offset of the material at the respective position of the first conveyor, these two-dimensional numbers [x, y] are exchanged for two-dimensional numbers [x, y*] indicating the axial offset of the material at the respective position of the loading conveyor.

[0022] During the winding of the material onto the respective bumper-tread or assembly drum, the corresponding axis position data is recalled from the cache according to the current position of the loading conveyor. During the winding process, the actuator moves the loading conveyor with its motion, which is always of the same magnitude but is oriented opposite to the data on the position of the material's axis, and thus compensates for the material undulating so that the position of the material's axis is always in the axis of the drum on which the material is wound. The permissible dimensions of the wound material for use on the respective assembly line are: minimum width 350mm, maximum width 1150mm, minimum length 971mm, maximum length 1853mm.

[0023] Brief Description of Drawings

[0024] Figure 1 shows a block diagram of a material centring unit according to the present invention.

[0025] Figure 2 shows the image sensing device of the centring unit.

[0026] Figure 3 shows the algorithm for calculating the position of the material's axis of the centring unit.

[0027] Figure 4 shows the undulated material placed on the conveyor.

[0028] Examples of the Embodiment

[0029] Example 1

[0030] Carcass material with a width of 750mm and a length of 1310mm was placed on a conveyor that moved at a speed of 500 mm / s. The material's axis was imaged at 60 Hz by the right and left camera sensors (1, 2). The spacing of the measured points was 8.33 mm. 157 images were taken of both the right and left edges of the material. The images were sent to the image signal processing unit, which calculated 157 data [xi to X157] about the current position of the material's axis and sent them to the PLC control system.

[0031] The calculation of [x] was performed according to the following algorithm:

[0032] The control system assigned to each data [x] a data [y] obtained by the encoder, which represents the current position of the conveyor of the respective centred material at the time of imaging. 157 two-dimensional numbers [x,y] were obtained and cached in the control system.

[0033] Based on the above example measurement, it was found that the axial offset of the material at the conveyor position of 1000 mm is -5. [-5;1000].

[0034] During the winding of the material onto the carcass drum, the actuator moved the conveyor on the basis of the two-dimensional numbers [x,y] from the control system cache memory and compensated with its motion, which is always of the same magnitude but opposite in orientation to the data [xn] about the position of the material's axis at the position of the loading conveyor at point n. In this way, the undulation of the material on the loading conveyor was compensated for so that the position of the material's axis was always in the axis of the drum onto which the material was being wound.

[0035] Example 2

[0036] Carcass material with a width of 750mm and a length of 1310mm was placed on a conveyor that moved at a speed of 500 mm / s. The material's axis was imaged at 200 Hz by the right and left camera sensors (1, 2). The spacing of the measured points was 2.5 mm. 524 images were taken of both the right and left edges of the material. The images were sent to the image signal processing unit, which calculated 524 data [xi to X524] about the current position of the material's axis and sent them to the PLC control system.

[0037] The calculation of [x] was performed according to the following algorithm: The control system assigned to each data [x] a data [y] obtained by the encoder, which represents the current position of the conveyor of the respective centred material at the time of imaging. 524 two-dimensional numbers [x,y] were obtained and cached in the control system.

[0038] Based on the above example measurement, it was found that the axial offset of the material at the conveyor position of 1400 mm is 5. [5;1400].

[0039] During the winding of the material onto the carcass drum, the actuator moved the conveyor on the basis of the two-dimensional numbers [x,y] from the control system cache memory and compensated with its motion, which is always of the same magnitude but opposite in orientation to the data [xn] about the position of the material's axis at the position of the loading conveyor at point n. In this way, the undulation of the material on the loading conveyor was compensated for so that the position of the material's axis was always in the axis of the drum onto which the material was being wound.

[0040] Example 3

[0041] Centring of the raw tyre materials before winding on the carcass drum was achieved by using a device - centring unit, the block diagram of which is shown in Figure 1.

[0042] The centring unit comprises a control system 7 with a cache memory and an image sensing device 5 comprising a right camera sensor 2 for sensing the right edge of the material 3 to be centred, and a left camera sensor 1 for sensing the left edge of the material 3 to be centred, placed on the conveyor (Figure 2).

[0043] The centring unit further comprises a unit 6 for processing image signals from the image sensing device 5, wherein said unit 6 recognizes the left and right edges of the material 3 to be centred from the image signals, detects the deviation a* and b*, and determines data [x] of the current position of the axis of the material , and sends said data to the control system 7 for entering to the cache memory. The algorithm for calculating the data [x] is shown in the flow chart in Figure 3.

[0044] The centring unit further comprises an encoder 8 which obtains data [y] of the current position of the conveyor, an actuator 9 which provides lateral movement of the loading conveyor according to two-dimensional numbers [x,y] or [x,y*] from the control system cache memory 7.

[0045] Example 4

[0046] Figure 4 shows material 3 placed on a conveyor (not shown) containing two example measurements of the deviation a, b of the right and left edges of material 3 at the current position of the conveyor: data y=1400 mm and data y=1000 mm.

[0047] In the first case (y=1400 mm), the right edge of the material deviates 5 mm to the right of the axis of the right camera sensor 2 and the left edge of the material deviates 5 mm to the right of the axis of the left camera sensor 1. Data [x] of the position of the material's axis is 5.

[0048] In the second case (y=1000 mm), the right edge of the material deviates 7 mm to the left of the axis of the right camera sensor 2 and the left edge of the material deviates 3 mm to the left of the axis of the left camera sensor 1. Data [x] of the position of the material's axis is -5.

[0049] List of reference signs:

[0050] 1 left camera sensor

[0051] 2 right camera sensor

[0052] 3 material

[0053] 4 direction of material's movement on the conveyor

[0054] 5 image capture device

[0055] 6 image signal processing unit

[0056] 7 control system (PLC)

[0057] 8 encoder

[0058] 9 actuator

Claims

P A T E N T C L A I M S1. A method of centring raw tyre materials on a conveyor of an assembly line comprising a first conveyor, a loading conveyor, and a carcass drum or a bumper drum characterised in that it comprises detecting a position of the raw tyre materials based on the presence of the left edge of the material in the field of view of a left camera sensor (1) and the right edge of the material in the field of view of a right camera sensor (2), which comprises the following steps:- detecting the presence of edges of the material placed on the loading conveyor during the movement of the loading conveyor, by the right camera sensor (2) and the left camera sensor (1) by periodically scanning the edge of the material along the entire length of the material (3), wherein each cycle consists of: a) sending a signal to a control system (7), if the right edge and left edge are present, that the measurement of the axis position of the material (3) is being initiated; b) detecting the position of the edge of the material to the right and / or left with respect to the axis of the field of view of the camera sensor (1), (2); c) determination of a deviation a from the axis of the field of view of the left camera sensor (1) and determination of a deviation b from the axis of the field of view of the right camera sensor (2); if the deviation a is to the left of the axis of the field of view a* = -a, if the deviation a is to the right of the axis of the field of view a* = a; if the deviation b is to the left of the axis of the field of view b* = - b, if the deviation b is to the right of the axis of the field of view b* = b; d) determination of the current position of the axis of the material (3)- a data [x], according to the formula x=(a*+b*) / 2; e) sending the data [x] to the control system (7), which assigns a data [y] to the data [x] about the current position of the loadingconveyor sensed by the control system using an encoder (8), to form a two-dimensional number [x,y], which carries information about the axial offset of the material (3) with respect to the central axis of the drum in the radial direction and the position where this axial offset is located on the loading conveyor; f) storing the two-dimensional number [x,y] in the control system (7) cache memory;- compensation of the axial offset of the material (3) with respect to the drum during material winding onto the drum, wherein the control system (7) moves the loading conveyor by means of an actuator (9) on the basis of two-dimensional numbers [x,y] from the cache memory.

2. The method of centring according to Claim 1, characterised in that the presence of edges of the material is detected on the first conveyor, and wherein the data [y] is an indication of the current position of the first conveyor, and wherein, when the material passes from the first conveyor to the loading conveyor, the data [y] is replaced by the data [y*] of the current position of the loading conveyor in two-dimensional numbers [x,y] stored in the cache memory to obtain the two- dimensional numbers [x, y*] of the position of the axial offset of the material on the loading conveyor, with a subsequent axial offset compensation of the material relative to the drum when the material is wound onto the drum, where the control system (7) moves the loading conveyor using the actuator (9) on the basis of the two-dimensional numbers [x, y*] from the cache memory.

3. The method of centring according to Claim 1 or 2, characterised in that the speed of movement of the first conveyor and the loading conveyor is 100 to 500 mm / s, preferably 500 mm / s.

4. The method of centring according to any one of Claims 1 to 3, characterized in that the frame rate of both the right and left camera sensors is 60 to 200 Hz, preferably 200 Hz.

5. A device for carrying out the method according to any one of Claims 1 to 4, characterized in that it comprises: o an image sensing device (5) comprising a right camera sensor (2) for sensing the right edge of the centred material and a left camera sensor (1) for sensing the left edge of a centred material (3) placed on the conveyor; o a unit (6) for processing image signals from the image sensing device, wherein said unit (6) is adapted to recognize left and right edges of the centred material (3) from the image signals, to determine deviations a and b, to calculate a data [x] which is the current position of the axis of the material, and to send the data [x] to a control system (7) of the assembly line; o at least one encoder (8) for sensing the current position of the loading conveyor and possibly also of the first conveyor; o an actuator (9) to ensure the lateral movement of the loading conveyor; o the control system (7) with cache memory adapted for the actuator (9) control and communication with the encoder (8).

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