Method for adjusting the length of material webs

Abstract

Method for adjusting the length (l0, l1) of material webs (2) based on at least one rubber compound for the production of a tire component, wherein the material webs (2) are spliced ​​on a build-up drum (3) of a tire building machine, comprising the following steps: a. Feeding a web of material (2) to the build-up drum (3) on a feeding device (1) at a transport speed set to a specific size, b. Determination of the length (l0) of the material web (2) on the feeding device (1) using a length measuring system (4), c. Winding the material web (2) onto the build-up drum (3), which rotates at a circumferential speed of a set size that differs from the transport speed of the feed device (1), so that the length (l1) of the material web (2) on the build-up drum is adjusted to a target length, d. Measurement of the splice area of ​​the material web (2) in the wound state using a splice measuring system (5), in particular the measurement of the distance or the extent of the overlap between the ends (2a, 2b) of the material web (2), characterized by that the data determined by the splicing measuring system (5) are input variables for an iterative control loop of a computer, which controls the transport speed of the feeding device (1) and adjusts it to the peripheral speed of the build-up drum (3), whereby the iterative control loop detects a tendency deviation of the distance or extent of the overlap between the ends (2a, 2b) of the material web (2) from the target value and subsequently corrects it automatically.

Description

[0001] The invention relates to a method for adjusting the length of material webs based on at least one rubber compound for the production of a tire component, wherein the material webs are spliced ​​on a build-up drum of a tire building machine, comprising the following steps: a. Feeding a web of material to the build-up drum on a feeding device at a transport speed set to a specific size, b. Determining the length of the material web on the feeding device using a length measuring system, c. Winding the material web onto the build-up drum, which rotates at a circumferential speed of a set value that differs from the transport speed of the feeding device, so that the length of the material web on the build-up drum is adjusted to a target length, d. Measurement of the splice area of ​​the material web in the wound state using a splice measuring system, in particular the measurement of the distance or the extent of the overlap between the ends of the material web.

[0002] During tire manufacturing, material webs are wound onto drums in tire-building machines to form a tire blank. The ends of these webs can then be spliced ​​either butt-jointed or with a defined overlap. These material webs are, for example, extruded or calendered from rubber compounds, cut to a specific length for the production of treads, inner layers, and the like. Material webs containing reinforcing elements, such as steel or textiles, are used to manufacture carcass plies or belt plies.

[0003] Ideally, material webs for treads should be cut in such a way that their ends can be butt-spliced ​​together after being wound onto the winding drum. Only slight deviations between the actual length of the material webs and their target lengths for splicing are permissible during this process.

[0004] When manufacturing components from material webs, deviations can occur between the target length and the actual length of the material web. These deviations can be attributed, for example, to fluctuating material properties of the raw materials used to produce the webs. However, deviations can also occur during the laying process of the material web onto the build-up drum. Such deviations can be caused by stress relaxation or thermal influences. Therefore, splice measurement systems are installed for quality control of the splice area. These systems measure the degree of overlap between the ends of a material web or the distance between the ends to be spliced. Such splice measurement systems are known, for example, from EP 0 530 673 B1, DE 10 2006 059 416 A1, and DE 100 36 010 A1.

[0005] In the method known from EP 0 530 673 B1, the ends of a web of material are detected by a detector while it is being wound onto a drum. Simultaneously, an angle measuring device located on the drum determines the angular positions of the drum corresponding to the ends of the web. From these values, the length of the web and the overlap length or gap between the ends of the web can be determined by an evaluation unit.

[0006] From DE 10 2006 059 416 B4 an optical measuring system and a method for measuring object surfaces, which can increase the measuring accuracy of digital 3D geometry measuring systems, are known.

[0007] From DE 41 08 515 A1, a method for winding material webs onto the winding drums of a tire manufacturing machine is known. The length of the material web is measured on a feeding device. The ratio of the speed of the feeding device to the circumferential speed of the winding drum is set to the ratio L / L0. L corresponds to the length of the unwound portion of the material web, and L0 corresponds to the remaining circumferential length of the winding drum not yet covered with material. The material web is wound only if the ratio L / L0 lies within a defined range.

[0008] To ensure consistent splicing, it is common practice to cut material webs so that their actual length is slightly less than the target length. Subsequently, the webs are stretched slightly during winding onto the build-up drum, thus achieving their target lengths for splicing. The degree of length change is adjusted by the ratio of the build-up drum's peripheral speed to the feeder's transport speed. If the webs are slightly too short or too long, the ends can be pressed together manually.

[0009] If the splicing measurement system detects that some successive splicing operations could not be carried out optimally, either due to overlapping material web ends (overlapping splice) or due to a gap between the ends of the material web (open splice), i.e., there was an overlap of the material web ends or a gap between the ends on the build-up drum, it is common practice for the tire building machine operator to manually correct this by adjusting corresponding operating parameters, generally the transport speed of the feeding device but also the rotational speed of the build-up drum, so that the splicing process can be carried out optimally again.

[0010] These manual corrections are made by the operator based on their individual observations. The operator should therefore be able to recognize a trend, i.e., a systematic deviation of the actual length from the target length of the material web, and correct accordingly. This requires close attention, as any deviation from the target length must be compared with the measurement result of the splice measuring system of the preceding tire blank to determine whether it is a one-off, i.e., random, deviation or a recurring, i.e., systematic, deviation of the actual length from the target length. The manual corrections made by the operator are prone to errors and subject to a certain degree of randomness regarding their success rate, and are often not successful within a reasonable timeframe.

[0011] DE 44 07 964 A1 describes the feeding of a cut material strip onto a winding drum and the control of the speed for compressing or stretching the material strip. The length and position of the second end are recorded by a camera to allow for corrections to be made to the second half of the same material web. DE 10 2012 016 587 A1 describes moving the material under at least one laser source during feeding, which projects strip- or point-shaped light patterns. A camera evaluates the image of these patterns to determine the height. The position of the section being examined is recorded, enabling statements about the splice quality before, during, and after winding. The measurement data can be automatically checked against predefined parameters / tolerances. In the event of an impermissible deviation, a signal is triggered so that the operator can make corrections; otherwise, the manufacturing process for the affected tire is aborted.US 2010 / 0186872 A1 describes how to precisely adjust the tension profile or the deposit profile of a continuous elastic element during depositing on the drum, i.e. within the same deposit, depending on the time.

[0012] The invention is therefore based on the objective of improving a method of the type mentioned at the outset in such a way that the problems associated with a manual change of the parameters no longer occur.

[0013] The problem is solved according to the invention by using the data determined by the splicing measuring system as input variables for an iterative control loop, which regulates the transport speed of the feeding device and adjusts it to the peripheral speed of the build-up drum.

[0014] An iterative control loop detects any deviation in the distance or extent of overlap between the ends of a material web from the target value and subsequently corrects it automatically. This control system synchronizes the transport speed of the feeder with the peripheral speed of the build-up drum, ensuring that the material webs ultimately have the ideal length for the specified splicing process. This reduces operator workload and enables automatic, fast, and precise regulation of the splice area.

[0015] In a preferred embodiment of the invention, the material web is adjusted to the target length by stretching during winding onto the winding drum. Such longitudinal stretching is particularly easy to implement using the iterative control loop according to the invention.

[0016] In a preferred embodiment of the invention, the extent of the adjustment of the material web length is described by means of a mathematical function, preferably a linear function. Compared to more complex functions, linear functions have only two constants, which makes it particularly easy to understand, for example, the extent of longitudinal elongation.

[0017] It is particularly advantageous if additional parameters and / or data transmitted by the tire manufacturing machine serve as input variables for the iterative control loop, as this allows for further optimization of the splicing process. These input variables preferably include the results of length measurements, the thickness of the material web, the quantities of substances in the rubber compound, the tackiness of the rubber compound, and / or the storage time of the materials used. Preferably, the input variables can be based on systematic process subcalculations, which are particularly relevant due to cassette, material, and dimension changes. Deformed material edges can also be detected during the length measurements. Feeding this data into the regression algorithm further optimizes the correction of the material web. Alternatively, the iteration loop is restarted.These measures allow for a particularly efficient and rapid correction of the length change of the subsequent material web for the next splicing process.

[0018] Further features, advantages and details of the invention will now be explained in more detail with reference to the drawing, which depicts an exemplary embodiment. The drawing shows... Fig. 1 to Fig. 3 schematic representations of process steps for and during the application and splicing of a material web, here exemplified by a material web for a tread of a vehicle pneumatic tire.

[0019] The tread of a vehicle tire is typically manufactured from an extruded or calendered web of material made from a rubber compound. A feeding device transports the web to a build-up drum of a tire manufacturing machine, where it is applied and butt-spliced. In the following, "web" refers to the web already cut to a specific length.

[0020] Fig. Figure 1 shows a feeding device 1 comprising a conveyor belt, a material web 2, a build-up drum 3, a length measuring system 4 equipped with two sensors, and an optical splicing measuring system 5. The material web 2 has an initial length l0 and two ends 2a and 2b, the two ends 2a and 2b being spliced ​​together during the subsequent splicing process.

[0021] On the feeding device 1, the output length l0 of the material web 2 is determined by the length measuring system 4 arranged above the feeding device 1 and stored in a computer (not shown). Advantageously, at least three coordinates distributed across the width of the leading edge of the material web are also determined and recorded by the computer in the area of ​​the two material web ends 2a, 2b. This allows angled edges, such as those required for material webs intended for tire belts, as well as curved sections of the material web 2 and any length and width deviations between material webs 2 to be registered.

[0022] The measured material web 2 is then transported via the feed device 1 in the direction of arrow P1 to the build-up drum 3, which rotates at a specific peripheral speed. The transport speed of the feed device 1 corresponds to the speed of the conveyor belt circulating on it and differs from the peripheral speed of the build-up drum 3.

[0023] In Fig. 2. The material web 2 has already been transported to the build-up drum 3 and wound onto it. During this process, depending on the ratio of the circumferential speed of the build-up drum 3 to the transport speed of the feeding device 1, the material web 2 stretches, increasing its length by Δl compared to the initial length l0. iThe material web 2 is enlarged. The respective speeds are usually chosen so that the elongation is a maximum of 3%. The stretched material web 2 has an actual length l1, which generally corresponds to the desired target length for the splicing process, the circumferential length of the build-up drum 3. In this case, there is neither an overlap nor a gap between the ends 2a, 2b of the material web 2 on the build-up drum 3.

[0024] Due to fluctuating material properties of the raw materials required for the production of the material webs 2 for the running strips, deviations can occur between the desired target length and the actual length l1 of the stretched material web 2. Furthermore, the additional use of rollers during the application process, which exert pressure on the material web 2, can also lead to deviations between the target and actual length l1. As described in Fig.As shown in Figure 3, this typically results in a gap of several millimeters between the ends 2a and 2b of the material web 2 when wound on the drum 3. With gaps of this magnitude, a splicing process can only be carried out if the ends 2a and 2b are pressed together manually, for example by the operator.

[0025] The magnitude of the deviation between the target and actual length l1 is detected and measured by the splice measuring system 5 located at the splice area, with the relevant data being stored in the computer. While in previously known devices and methods the splice measuring system 5 performs only a monitoring function, in the invention, a control loop between the splice measuring system 5 and the feeding device 1 not only detects any systematic deviation of the target length from the actual length l1 of the material web 2, but also automatically corrects it for subsequent material webs 2.

[0026] For this purpose, the measurement results from the splicing measuring system 5, i.e., the measurement of the distance between the ends 2a and 2b of the material web 2 to be spliced, are processed in the computer using a regression algorithm. Further parameters and / or data related to any material and dimension changes performed, as well as other data transmitted by the tire manufacturing machine, such as the results of length measurements or the material thickness, can be included in the regression algorithm. In particular, the coordinates determined by the length measuring system 4 in the area of ​​the material web edges are also incorporated into the regression algorithm. Therefore, if deviations from the target length occur several times in succession, the computer recognizes a systematic deviation of the actual length from the target length.This information is passed on via the control loop to the feed device 1 and its transport speed is changed so that the next material web 2 is not delayed by Δl. i but by a value Δl i+1 is stretched. This adjusts the length of material web 2 so that an automatic splicing process can be carried out again. The value Δl i+1 for example, by means of a linear regression function of the general form Δli+1=a^×Δli+e^ determined. â and ê are process parameters, where â, ê = f (splice measurement) 1....i ) applies.

[0027] As long as the systematic deviation is not corrected, the control loop operates iteratively, meaning that the splicing process is automatically optimized through continuously repeating process steps. These process steps take into account the data from the measurement of the splice area, the calculation of the deviation of the actual length from the target length, and the transport speed of the feeder 1. The changed transport speed, due to the altered elongation of the incoming material web 2, immediately affects the next splicing process and is therefore immediately detected by the splicing measuring system 5 and compared with the target length, resulting in a self-optimizing system. This ensures rapid and precise optimization of the splice quality, guaranteeing optimal splice quality even with fluctuating material composition of the web and thus increasing productivity.

[0028] Furthermore, the regression algorithm can take additional parameters into account, such as the quantities of substances in the rubber compound, the stickiness of the rubber compound, or the storage duration of the materials used. Additional parameters can be based on systematic process subcalculations, such as those that occur when changing cassettes or materials, or when the dimensions of the component being manufactured change.

[0029] The invention can be used in tire manufacturing processes that utilize pre-cut material webs. Further examples include the application of carcass and belt layers or inner layers onto build drums.

[0030] The hardware and software required for the control process are not the subject of the invention. Reference number list 1 ....................... Feeding device 2 ....................... Material track 2a, 2b ............... Ends of the material web 3 ....................... Assembly drum 4 ....................... Length measuring system 5 ....................... Splice measuring system l0 ....................... Initial length of the material web l1 ....................... Actual length Δl i ..................... Change in length due to stretching

Claims

[1] Method for adjusting the length (l0, l1) of material webs (2) based on at least one rubber compound for the production of a tire component, wherein the material webs (2) are spliced ​​on a build-up drum (3) of a tire building machine, comprising the following steps: a. Feeding a web of material (2) to the build-up drum (3) on a feeding device (1) at a transport speed set to a specific size, b. Determination of the length (l0) of the material web (2) on the feeding device (1) using a length measuring system (4), c. Winding the material web (2) onto the build-up drum (3), which rotates at a circumferential speed of a set size that differs from the transport speed of the feed device (1), so that the length (l1) of the material web (2) on the build-up drum is adjusted to a target length, d. Measurement of the splice area of ​​the material web (2) in the wound state using a splice measuring system (5), in particular the measurement of the distance or the extent of the overlap between the ends (2a, 2b) of the material web (2), characterized by , that the data determined by the splicing measuring system (5) are input variables for an iterative control loop of a computer, which controls the transport speed of the feeding device (1) and adjusts it to the peripheral speed of the build-up drum (3), whereby the iterative control loop detects a tendency deviation of the distance or extent of the overlap between the ends (2a, 2b) of the material web (2) from the target value and subsequently corrects it automatically. [2] Method according to claim 1, characterized by , that the material web (2) is adjusted to the target length by stretching during winding onto the build-up drum (3). [3] Method according to claim 1 or 2, characterized by , that the extent of the adjustment of the length of the material web (2) is described by means of a mathematical function. [4] Method according to claim 3, characterized by that the mathematical function is a linear function. [5] Method according to any one of claims 1 to 4, characterized by that further parameters and / or data transmitted by the tire manufacturing machine are input variables for the iterative control loop. [6] Method according to claim 5, characterized by , that the input variables include the results of the length measurements, the thickness of the material web (2), quantities of substances in the rubber compound, the stickiness of the rubber compound and / or the storage time of the materials used. [7] Method according to claim 6 or 7 characterized by that the input variables are based on systematic process undercalculations, which are caused in particular by changes in cassettes, materials and dimensions.

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