METHOD AND APPARATUS FOR CORRECTING THE FEED DISTANCE OF A CUTTING STRIP

Abstract

The invention relates to a method and apparatus for correcting a feed distance of a strip for cutting, wherein the method comprises the steps of: - feeding the strip over the feed distance in a feed direction towards a cutting line extending at a cutting angle oblique to said feed direction; - detecting a lateral position of a first longitudinal edge of the strip in a lateral direction perpendicular to the feed direction; wherein, when the detected lateral position is displaced over a displacement distance in the lateral direction with respect to a reference position for the first longitudinal edge on the measuring line, the method further comprises the step of: - adjusting the feed distance with a correction distance that is related to the displacement distance in a proportion that is defined by the cutting angle.

Description

METHOD AND APPARATUS FOR CORRECTING THE FEED DISTANCE OF A CUTTING STRIP BACKGROUND The invention relates to a method and apparatus for correcting a feed distance of a cutting strip, in particular a strip for tire construction. Patent JP 2014 218065 A discloses a method for adjusting the cutting position of a tape member so that the tape member can be cut to a certain length. In the method, a tape member is cut by a tape cutter and then conveyed by a transport medium and wound around a winding body. The tip of the tape member, positioned on the transport medium, is cut obliquely at a certain angle with respect to the longitudinal direction by the tape cutter. The tape member is then conveyed until the tip of the tape member formed by the cut reaches a central position of the width-sensing sensor, and the width of the tip is measured. When the width is wider than a reference value, the conveying speed is reduced to transport the rear end of the tape member to the tape cutter.When the width is smaller than the reference value, the amount of transport is increased to move the rear end of the tape member to the tape cutter. The amount of correction is expressed as v = tan'A, where V is the amount of correction in the longitudinal direction of the tape member and x is the difference in the width direction. BRIEF DESCRIPTION OF THE INVENTION The known method according to JP 2014 218065 A requires creating the tip before measurement. In other words, the amount of correction can only be determined when the leading end of the tape member has already been cut and the tip passes over the width detection sensor. The amount of transport is then adjusted to carry the trailing end of the tape member to the tape cutter. However, this adjustment does not take into account that the trailing end may be in a different lateral position than the leading tip, and that this also has a considerable effect on the length of the tape member. Furthermore, the width detection sensor of JP 2014 218065 A consists of a plurality of light-emitting and light-receiving units arranged on the upper and lower sides of the tape member for measuring width.This width detection sensor is relatively complex and expensive. It is an object of the present invention to provide a method and apparatus for correcting a feed distance of a cutting strip, wherein the determination of the correction distance can be improved. According to a first aspect, the invention provides a method for correcting a feed distance of a strip for cutting, wherein the strip has a strip body extending longitudinally, a first longitudinal edge extending on the first side of the strip body, and a second longitudinal edge extending on a second side of the strip body opposite the first side, wherein the method comprises the steps of: feed the strip over the feed distance in a feed direction towards a cutting line that extends at a cutting angle oblique to that feed direction; detect a lateral position of the first longitudinal edge along a measuring line; wherein, when the detected lateral position is displaced over a displacement distance in a lateral direction perpendicular to the feed direction with respect to a reference position for the first longitudinal edge on the measuring line, the method further comprises the step of: Adjust the feed distance with a correction distance that is related to the offset distance in a proportion that is defined by the cutting angle. The lateral position of the first longitudinal edge relative to the cut line determines where the cut line, which extends at the oblique cutting angle, will intersect, and therefore cut, the first longitudinal edge. A lateral displacement can result in the cut line intersecting the first longitudinal edge earlier or later than expected, thus causing a shorter or longer strip length than anticipated. Because the strip is cut twice, the lateral position of the first longitudinal edge at both the leading and trailing edges significantly influences the overall strip length. Furthermore, the lateral displacement can differ at the leading edge compared to the trailing edge, potentially amplifying the effect. By detecting the lateral position of the first longitudinal edge, it's possible to predict or calculate where the cutting line will intersect the first longitudinal edge and, therefore, what the effect of any lateral displacement will be on the total strip length. The conveying rate or feed distance can then be adjusted accordingly to compensate. The lateral position of the first longitudinal edge can be detected at any point during conveying, as it is independent of the formation of the leading edge. Detection can be performed, for example, before cutting and / or upstream of the cutting line. Therefore, the conveying rate for both the leading and trailing edges can be adjusted according to the lateral position of the first longitudinal edge relative to the leading and trailing edges, respectively. Furthermore, by adjusting the feed distance based on the displacement distance of the detected lateral position, it is not necessary to measure the entire width of the strip. For example, a single sensor with a relatively small detection area can be used to detect the lateral position of the first longitudinal edge.Therefore, the determination of the correction distance can be significantly simplified, thereby reducing the complexity and / or costs of the system as a whole. In a preferred embodiment, the lateral position of the first longitudinal edge is detected on the measuring line upstream of the cutting line with respect to the feed direction. Therefore, the feed distance and / or the transport quantity for both the leading and trailing edges can be adjusted according to the lateral position of the first longitudinal edge on said leading and trailing edges, respectively. In another embodiment, the reference position is located on the measuring line at a reference distance from the cutting line in the feed direction. The detected lateral position, when moved over the displacement distance, is at a distance greater or less than the reference distance from the cutting line in the feed direction. The feed distance is adjusted by adding the correction distance to the reference distance in the case of a greater distance and subtracting the correction distance from the reference distance in the case of a lesser distance. Therefore, the strip can be advanced from the measuring line to the cutting line along a feed distance such that the cutting line intersects the detected lateral position at the first longitudinal edge. In another embodiment, the method comprises the following steps: Compare the detected lateral position with the reference position to determine the displacement distance; and calculate the correction distance in the feed direction using a trigonometric function with a first parameter indicative of the cutting angle and a second parameter indicative of the displacement distance as parameters; and adjust the feed distance based on the calculated correction distance. A trigonometric function can provide a relatively simple way to determine the correction distance, given that the cut angle and the displacement distance are known. Preferably, the trigonometric function is a tangent. More preferably, the trigonometric function is correction distance = displacement distance / tan A, where A is the cut angle. Alternatively, the trigonometric function is correction distance = displacement distance / displacement distance, where A is the equivalent of ninety degrees minus the cut angle in degrees. Both functions have the same result and differ only in how the parameter A is defined in terms of the cut angle. In yet another alternative embodiment, a range of values ​​indicative of the correction distance associated with a range of lateral positions is stored in a database, wherein the method comprises the steps of: Retrieve a value from the range of values ​​that is associated with a lateral position from the range of lateral positions that corresponds or substantially corresponds to the detected lateral position of the first longitudinal edge and use that value as the correction distance to adjust the feed distance. The relationship between the correction distance and the lateral positions can be determined experimentally or mathematically before the steps of the aforementioned method to generate a range of values ​​that can be easily consulted during the method. Such predefined values ​​can also be useful for determining the appropriate correction distance. In another embodiment, the reference position is a fixed position. The reference position could be, for example, the most optimal lateral position of the first longitudinal edge for cutting. In another embodiment, the method comprises the following steps: cut the strip on the cutting line to form a leading edge with respect to the feed direction; feed the strip in the feed direction over the feed distance; and cut the strip on the cut line to form a trailing edge with respect to the feed direction; wherein the first longitudinal edge has an edge length in the feed direction between the leading and trailing edges; and wherein, when the lateral position of the first longitudinal edge is displaced laterally at the trailing edge relative to the leading edge, the feed distance is adjusted by a correction distance so that the edge length is constant or substantially constant regardless of such displacement. Therefore, more uniform strip lengths can be obtained. Preferably, the lateral position of the first longitudinal edge is detected at least twice along the edge's length, wherein the first detected lateral position of the at least two detected lateral positions is used as a reference position to determine the displacement distance for the second detected lateral position of the at least two detected lateral positions. Unlike the embodiment that had a fixed reference position, the current embodiment compares the two detected lateral positions with each other. More preferably, the first detected lateral position is separated from the second detected lateral position in the feed direction along the length of the edge. In other words, the first detected lateral position is the lateral position of the first longitudinal edge at the leading edge, and the second detected lateral position is the lateral position of the first longitudinal edge at the trailing edge. The lateral positions can thus be detected along the first longitudinal edge at the positions where the leading and trailing edges are ultimately formed by shearing. In another embodiment, the method, before cutting the strip to form the front edge, comprises the following steps: detect a first lateral position of the first longitudinal edge on the measuring line upstream of the cutting line with respect to the feed direction; and feed the strip over a first part of the feed distance that is corrected with the correction distance so that the first detected lateral position is located on the cutting line after feeding the strip over the first part of the feed distance. Consequently, the strip is placed after the first part of the feed distance in a position where the cutting line intersects the first longitudinal edge at the first detected lateral position, i.e., corresponding to where the lateral position of the first longitudinal edge was detected on the measuring line. Preferably, the method, after cutting the strip to form the front edge and before cutting the strip to form the back edge, comprises the steps of: feed the strip over a second part of the feed distance that corresponds or substantially corresponds to the edge length less the first part of the feed distance; detect a second lateral position of the first longitudinal edge on the measuring line; and feed the strip over one-third of the feed distance that is corrected with the correction distance so that the second detected lateral position is located on the cutting line after feeding the strip over one-third of the feed distance. After the strip has been fed over the second part of the feed distance, the second lateral position detected on the measuring line represents the lateral position where the cutting line would intersect the first longitudinal edge. Based on this second lateral position, the third part of the feed distance can be determined and corrected to ensure that, after cutting, the edge length between the first and second lateral positions matches the desired edge length for the strip. In another embodiment, the lateral position of the first longitudinal edge is detected on the measuring line upstream of the cutting line with respect to the feed direction, where the cutting line converges towards the measuring line at one of the first longitudinal edge and the second longitudinal edge. Preferably, the cutting line is adjustable to extend at an oblique cutting angle opposite the feed direction, where the cutting line converges toward the measuring line on the opposite side of the first longitudinal edge and the second longitudinal edge, wherein the method steps are performed relative to the second longitudinal edge instead of the first longitudinal edge when the cutting line extends at the alternative oblique cutting angle. The adjustable cutting line allows strips to be cut at different or opposite inclined angles. The lateral position can be determined on either the first or second longitudinal edge, depending on which longitudinal edge provides the most relevant information for determining the correction distance. In another embodiment, the measuring line extends laterally, perpendicular to the feed direction. The measuring line is thus positioned at a neutral or right angle to the feed direction. This can greatly simplify the calculation of the correction distance, as it is not necessary to consider any oblique angle of the measuring line and its effect on the measurements. According to a second aspect, the invention provides an apparatus for correcting a feed distance of a strip for cutting, wherein the strip has a strip body extending longitudinally, a first longitudinal edge extending on the first side of the strip body, and a second longitudinal edge extending on a second side of the strip body opposite the first side, wherein the apparatus comprises: a cutter to cut the strip along a cutting line; a conveyor for feeding the strip along the feed distance in a feed direction towards the cutting line, wherein the cutting line extends at a cutting angle oblique to said feed direction; a drive to control the conveyor; a sensor device for detecting a lateral position of the first longitudinal edge along a measuring line; and a control unit that is operatively connected to the sensor device and the drive, wherein the control unit is configured to: Adjust the feed distance when the detected lateral position is displaced over a displacement distance in a lateral direction perpendicular to the feed direction with respect to a reference position for the first longitudinal edge on the measuring line, wherein the feed distance is adjusted with a correction distance that is related to the displacement distance in a relationship that is defined by the cutting angle. The control unit of the apparatus is arranged to control the apparatus in such a way that the feed distance is substantially the same as in the method according to the first aspect of the invention. Therefore, the apparatus has the same technical advantages as the method, which will not be repeated hereafter. It will also be clear that, in addition to the embodiments mentioned below, the apparatus can be combined with any one of the embodiments of the method, wherein the control unit is configured to control and / or execute the steps of the method described therein. In a preferred embodiment, the measuring line is located upstream of the cutting line with respect to the feed direction. Therefore, the feed distance and / or the amount of material transported for both the leading and trailing edges can be adjusted according to the lateral position of the first longitudinal edge on the leading and trailing edges, respectively. In another embodiment, the measuring line extends laterally, perpendicular to the feed direction. The measuring line is thus positioned at a neutral or right angle to the feed direction. This can greatly simplify the calculation of the correction distance, as it is not necessary to consider any oblique angle of the measuring line and its effect on the measurements. In another preferred embodiment, the sensor device comprises a first sensor for detecting the lateral position of the first longitudinal edge along the measuring line. This first sensor may have a relatively small detection area and may be of relatively simple construction, thereby reducing the complexity and / or cost of the overall apparatus. Preferably, the sensor device comprises a second sensor to detect the lateral position of the second longitudinal edge, wherein the cutting line is adjustable to extend at an oblique cutting angle alternative to the feed direction, wherein the control unit is arranged to adjust the feed distance relative to the detected lateral position of the second longitudinal edge instead of the first longitudinal edge when the cutting line extends at the alternative oblique cutting angle. The second sensor has the same technical advantages as the first sensor. Furthermore, the provision of the second sensor allows the lateral position of either the first or the second longitudinal edge to be determined, depending on which longitudinal edge provides the most relevant information for determining the correction distance. It is observed that, for the purpose of determining the correction distance, it is not necessary to use both sensors simultaneously. The various aspects and features described and shown in the descriptive specification may be applied individually, where possible. These individual aspects, in particular the aspects and features described in the appended dependent claims, may be the subject of divisional patent applications. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be clarified by way of an exemplary embodiment shown in the accompanying schematic drawings, in which: Figure 1 shows a side view of an apparatus for correcting a feed distance of a cutting strip according to the invention; Figure 2 shows an isometric view of the apparatus according to Figure 1; Figure 3A shows a strip correctly aligned and cut on a cutting line; Figures 3B and 3C show top views of the strip and the potential length differences of said strip at the cutting line as a consequence of misalignment with respect to the correct alignment of Figure 3A; Figure 4 shows a detail of the length difference according to circle IV of Figure 3B; Figure 5 shows a detail of the length difference according to the i zcfrnn / zznz / E / YiAi circle V of Figure 3C; Figures 6A, 6B, 6C, and 6D show the steps of a method for correcting a strip feed distance using the apparatus according to Figures 1 and 2; and Figure 7 shows the steps of an alternative method for correcting a strip feed distance using the apparatus according to Figures 1 and 2. DETAILED DESCRIPTION OF THE INVENTION Figures 1 and 2 show an apparatus 1 for correcting a transport quantity or feed distance F1, F2, F3 of a strip 9 for cutting. As shown in Figure 6A, strip 9 has a strip body 90 extending in a longitudinal Y direction, a first longitudinal edge 91 extending on a first side of the strip body 90, and a second longitudinal edge 92 extending on a second side of the strip body 90 opposite the first side. The longitudinal edges 91 and 92 do not always extend parallel to the longitudinal Y direction. Instead, they can deviate slightly in a lateral X direction perpendicular to the longitudinal Y direction, as exaggeratedly shown in Figure 6A. Strip 9 is preferably a tire component for manufacturing a green or unvulcanized tire. In this particular example, strip 9 is used to manufacture cord-reinforced protective plies. Such cord-reinforced protective plies are typically cut from a continuous strip at an oblique cutting angle parallel or substantially parallel to the direction of the reinforcing cords embedded in that continuous strip. The resulting strip 9 has a substantially rhomboidal outline, as shown in Figure 6D, which is characteristic of protective plies. After cutting, strip 9 forms a tire component having a leading edge 93 and a trailing edge 94 with respect to the feed direction F. The first longitudinal edge 91 further has a rim length L in the feed direction F between the leading edge 93 and the trailing edge 94.Preferably, this rim length L is kept uniform over a batch of tire components. Figure 1 schematically shows that, in this example embodiment, the apparatus 1 comprises a rear conveyor 11 and a front conveyor 12 for feeding the strip 9 in a feed direction F through a cutting line C between the rear conveyor 11 and the front conveyor 12. Alternatively, a single conveyor (not shown) extending across the cutting line C may be used, wherein a cutting bar, known per se, may be provided on the single conveyor for cutting the strip S on the continuous surface of the single conveyor. The apparatus 1 further comprises a drive 10 for driving the rear conveyor 11. A similar drive (not shown) is arranged on the front conveyor 12. As shown in Figures 3A, 3B, and 3C, the cutting line C is arranged at an oblique cutting angle H with respect to the feed direction F. The rear conveyor 11 and the front conveyor 12 are separated in the feed direction F to facilitate skew cutting along said cutting line C. The apparatus 1 further comprises a cutter 2, i.e., a disc cutter, for cutting the strip 9 along said cutting line C. The disc cutter can cooperate with the opposing member (not shown), i.e., another disc cutter or a cutting bar, in a manner known per se to obtain an accurate cut. Preferably, the cutting angle H is adjustable, i.e., by adjusting the orientation of a cutting frame (not shown), known per se, which supports the cutter 2 with respect to the rear conveyor 11, to change the orientation of the cutting line C. In particular, the cutting angle H can be adjusted within a range of ten to forty degrees with respect to the feed direction F or can even be moved more than ninety degrees or more to obtain a cutting angle that is opposite to the cutting angle H as shown in Figure 3A. As shown in Figure 1, the apparatus 1 further comprises a sensor device 3 that is arranged at or near the entry point of the strip 9 into the rear conveyor 11. The sensor device 3 is used to determine the lateral position of the first longitudinal edge 91 and / or the second longitudinal edge 92 along a measuring line M extending in the lateral direction X, as shown in Figure 2. Alternatively, the measuring line M can extend at an angle i oblique or not straight to the feed direction F, although this will make the correction, as described below, a little more complex. Preferably, the sensor device 3 is an optical sensor device. The sensor device 3 may comprise, for example, one or more sensors and / or imaging cameras. The sensor device 3 optionally includes a laser (not shown) for projecting a laser line onto the strip 9. Alternatively, mechanical means may be used to 'sense' the lateral position of the longitudinal edges 91, 92 of the strip 9 through direct contact. The sensor device 3 is located upstream of the cutting line C with respect to the feed direction F. In this case, the sensor device 3 is located above the rear conveyor 11. However, the sensor device 3 may also be located below the rear conveyor 11, partially above and below it, or upstream of it. In this example embodiment, as best seen in Figure 2, the sensor device 3 comprises a first sensor 31 and a second sensor 32 for detecting the lateral position of the first longitudinal edge 91 and the second longitudinal edge 92, respectively. It is noted that the invention requires only one of the sensors 31, 32 to operate. However, the other sensor 31, 32 can be used to provide additional information or can be kept inactive during at least part of the operation. In particular, the apparatus 1 can alternate between the first sensor 31 and the second sensor 32 depending on the lateral position of the longitudinal edge 91, 92, which is used as input for correction, as described in more detail below. The apparatus 1 further comprises a control unit 4 that is operatively connected to the sensor device 3 and the drive 10 to control the drive 10 and the operation of the rear conveyor 11, in response to detection signals representative of the lateral position of the first longitudinal edge 91 and / or the second longitudinal edge 92. In particular, the control unit 4 is arranged to adjust the feed distance over which the strip 9 is conveyed or advanced before, between and / or after the cuts. i zcfrnn / zznz / E / YiAi A method for correcting the feed distance F1, F2, F3 of the strip 9 for cutting will now be explained with reference to Figures 1-7. Figures 3A, 3B, and 3C show the potential impact of a lateral displacement distance of the first longitudinal edge 91 on the length of strip 9. In particular, Figure 3A shows strip 9 correctly aligned and cut at oa along the cut line C. More specifically, the first longitudinal edge 91 of strip 9 is located on or collinear with a lateral reference position R for said first longitudinal edge 91. At said lateral reference position R, the measuring line M is separated from the cut line C by a reference distance L1.In other words, when the first longitudinal edge 91 is aligned along the lateral reference position R and the strip 9 is carried, advanced or fed from the measuring line M over a feed distance equal to the reference distance L1 in the feed direction F, the length of the first longitudinal edge 91 between the measuring line M and the cutting line C will be equal to that reference distance L1. Figures 3B and 3C show the possible length differences of the strip at the cutting line as a result of misalignment with respect to the correct alignment shown in Figure 3A. In particular, in Figure 3B, the first longitudinal edge 91 is displaced by a first lateral displacement distance D1 in the lateral direction X with respect to the lateral reference position R. When the strip 9 advances by the same distance in the feed direction F as in Figure 3A, the length of the first longitudinal edge 91 between the measuring line M and the cutting line C has effectively increased to a length L2 greater than the reference distance L1.Figure 3C shows that when the first longitudinal edge 91 is displaced in the opposite direction over a second lateral displacement distance D2, the length of the first longitudinal edge 91 between the measuring line M and the cutting line C has effectively decreased to a length L3 less than the reference distance L1. The method according to the present invention aims to compensate for these length differences by determining a correction distance E1, E2, as shown in more detail in Figures 4 and 5, based on the lateral displacement distance i zcfrnn / zznz / E / YiAi D1, D2 and adding or subtracting said correction distance E1, E2 from the feed distances F1, F2, F3, as shown in Figures 6A, 6B, 6C and 6D, over which the strip S is carried in the feed direction F. To determine the correction distance E1, E2, the method according to the present invention comprises the following steps: feed the strip 9 over the feed distance F1, F2, F3 in a feed direction F towards a cutting line C that extends at an oblique cutting angle H to said feed direction F; and detect, at some time during feeding, the lateral position P1, P2 of the first longitudinal edge 91 along the measuring line M. As shown in Figures 6A, 6B, 6C, and 6D, when the detected lateral position P1, P2 is displaced over a displacement distance D1, D2, D3 in the lateral direction X with respect to the reference position R for the first longitudinal edge 91 on the measuring line M, the method further comprises the step of: Adjust at least a portion of the feed distance F1, F2, F3 with a correction distance E1, E2, E3 that is related to the displacement distance D1, D2 in a relationship that is defined by the cutting angle H. The displacement distance D1, D2, D3 can be determined by comparing the detected lateral position P1, P2 with the reference position R. Based on this determined displacement distance D1, D2, D3, the correction distance E1, E2, E3 in the feed direction F can be calculated using a trigonometric function, preferably a tangent, with a first parameter indicating the cutting angle H and a second parameter indicating the displacement distance D1, D2, D3. The cutting angle H can be entered into the device 1 manually by an operator or it can be determined automatically, i.e., using suitable sensors. The tangent trigonometric function can be expressed as displacement distance correction distance = -------------------------16 where Λ is the cut angle H. Alternatively, the tangent trigonometric function can be expressed as tan / 1 correction distance — —---------— ------------displacement distance in which 4 is the equivalent of ninety degrees minus the cut angle H in degrees. In yet another alternative embodiment, a range of values ​​indicative of the correction distance E1, E2, E3, associated with a range of lateral positions P1, P2, is stored in a database. The database may be part of the control unit 4 or located elsewhere. When using default data from a database, the relationship between the correction distance E1, E2, E3 and the cutting angle H is not actively calculated. Instead, it can be determined simply by retrieving a value from the range of values ​​that is associated with a lateral position P1, P2 from the range of lateral positions P1, P2 that corresponds or substantially corresponds to the detected lateral position P1, P2 of the first longitudinal edge 91. Figures 6A, 6B, 6C and 6D show in more detail which parts of the feed distance F1, F2, F3 are corrected at what time and depending on which detected lateral positions P1, P2. In particular, Figure 6A shows the strip 9 with a section of the strip body 90 that is still continuous, i.e., uncut. At a certain point in time, before the cutting of the leading edge 93, a first lateral position P1 of the first longitudinal edge 91 is detected on the measuring line M upstream of the cutting line C with respect to the feed direction F. The detection can be performed by the first sensor 31, as shown in Figure 2. The second sensor 32 is not required and can be inactive. The control unit 4 receives detection signals representing the first lateral position P1 from the sensor device 3 and determines a first correction distance E1 based on the aforementioned relationship between the first lateral position P1 and the cutting angle H. As shown in Figure 6B, strip 9 is subsequently fed over a first portion F1 of the feed distance F1, F2, F3 to move the portion of strip 9 that was located on the measuring line M during the detection of the first lateral position P1 to the cutting line C. The first portion F1 of the feed distance F1, F2, F3 is corrected by the correction distance E1 so that the first detected lateral position P1 is located on the cutting line C after feeding. More specifically, the first portion F1 of the feed distance F1, F2, F3 is equal to the reference length L corrected by the first correction distance E1. In other words, after feeding over the first portion F1 of the feed distance F1, F2, F3, the cutting line C intersects the first longitudinal edge 91 at the first lateral position P1.Therefore, when cutting strip 9 at said first lateral position P1, the impact of said first lateral position P1 on the total length of the tire component is known and appropriate measures are / can be taken to compensate for it. Note that the shaded part of strip 9 in figure 6B is the part of strip 9 that would have been cut off if the correction distance E1 had not been applied to the first part F1 of the feed distance F1, F2, F3. Figure 6C shows the situation after cutting strip 9 to form the leading rim 93 and before cutting strip 9 to form the trailing rim 94. Before cutting the trailing rim 94, an operator has entered a parameter to set the tire component length. Typically, this parameter is a rim length L for the first longitudinal rim 91 or the second longitudinal rim 92. In this case, a predefined rim length L is provided for the first longitudinal rim 91. As shown in Figure 6C, strip 9 has been fed over a second portion F2 of the feed distance F1, F2, F3 that corresponds to, or substantially corresponds to, the predefined rim length L minus the first portion F1 of the feed distance F1, F2, F3.Consequently, strip 9 is now located with a section of strip body 90 on the measurement line M where strip 9 would be cut to create the back edge 94 based on the predefined edge length L. i zcfrnn / zznz / E / YiAi To ensure that cutter 2 actually cuts strip 9 to the predefined edge length L, a second lateral position P2 of the first longitudinal edge 91 is detected on the measuring line M, as shown in Figure 6C. This detection can again be performed solely by the first sensor 31, as shown in Figure 2. Control unit 4 receives representative detection signals of the second lateral position P2 from sensor 3 and determines a second lateral displacement distance D2 by comparing the detected second lateral position P2 with the reference position R. Control unit 4 can then determine a second correction distance E2 based on the aforementioned relationship between the second lateral displacement distance D2 and the cutting angle H. Alternatively, control unit 4 can compare the second detected lateral position P2 with the first detected lateral position P1 and determine a third or displacement distance D3 based on the difference between these two lateral positions P1, P2. Control unit 4 can then determine a third or total correction distance E3 based on the aforementioned relationship between the third or total lateral displacement distance D3 and the cutting angle H. Now that the second lateral position P2 of the first longitudinal edge 91 is known and the second correction distance E2 (or the total correction distance E3) has been determined, the strip 9 can be fed beyond one-third F3 of the feed distance F1, F2, F3, as shown in Figure 6D. This third F3 of the feed distance F1, F2, F3 is corrected by the second correction distance E2 so that the second detected lateral position P2 lies on the cutting line C. In particular, this third F3 of the feed distance F1, F2, F3 is equal to the reference distance L1, as shown in Figure 3A, corrected by the second correction distance E2. Alternatively, this third F3 of the feed distance F1, F2, F3 is equal to the first F1 of the feed distance F1 corrected by the total correction distance E3.Now the strip 9 can be cut along the cut line C to create the trailing rim 94. Note that the cut line C intersects the first longitudinal rim 91 i zcfrnn / zznz / E / YiAi exactly at rim length L. Therefore, a tire component can be obtained with a rim length L that is constant or substantially constant regardless of the displacement of the first longitudinal rim 91 in the lateral X direction. Note that the shaded part of strip 9 in figure 6D is the part of strip 9 that would have been included if a correction distance E2, E3 had not been applied to the third part F3 of the feed distance F1, F2, F3. It is understood that the trailing edge 94 of the tire component created during the aforementioned method steps inherently creates a leading edge 93 on the strip 9 directly upstream of that tire component. The creation of that leading edge 93 constitutes the start of a subsequent cycle of the method. The detection of the second lateral position P2 in Figure 6C can therefore be simultaneous with the detection of the first lateral position P1 of a subsequent cycle of the method, i.e., for cutting the next tire component from the continuous strip 9. In other words, the second detected lateral position P2 can be used to determine the correction distance E2 required to obtain the desired rim length L of the current tire component, while the same correction distance E2 is also used as the correction distance E1 for cutting the leading edge 93 of the next tire component. Figure 7 schematically illustrates that the same or similar detection and determination can also be performed along the second longitudinal edge 92 as if it were the first longitudinal edge 91. In particular, the second sensor 32 of Figure 2 can be used to determine the lateral displacement distances D101, D102 of the first detected lateral position P101 and the second detected lateral position P102 with respect to a reference position R for the second longitudinal edge 92. The embodiment of Figure 7 has the additional advantage that the leading edge 93 can be cut from the sharpened leading tip at the intersection between the second longitudinal edge 92 and the leading edge 93 towards the first longitudinal edge 91, which can provide greater accuracy when creating the leading tip. It will also be appreciated that, when the cutting angle H is adjusted to an alternative cutting angle opposite to the cutting angle H as shown in Figures 6A, the steps of the aforementioned method can be performed in relation to the second longitudinal edge 92 instead of the first longitudinal edge 91 in a manner similar to Figure 7. It should be understood that the foregoing description is included to illustrate the operation of the preferred embodiments and is not intended to limit the scope of the invention. From the foregoing explanation, many variations that would still be covered by the scope of the present invention will be evident to those skilled in the art. In summary, the invention relates to a method for correcting a feed distance F1, F2, F3 of a strip 9 for cutting, wherein the method comprises the steps of: feed strip 9 over the feed distance F1, F2, F3 in a feed direction F towards a cutting line C that extends at an oblique cutting angle H to said feed direction F; detect a lateral position P1, P2 of a first longitudinal edge 91 of strip 9 in a lateral direction X perpendicular to the feed direction F; Wherein, when the detected lateral position P1, P2 is displaced over a displacement distance D1, D2, D3 in the lateral direction X with respect to a reference position R for the first longitudinal edge 91 on the measuring line M, the method further comprises the step of: Adjust the feed distance F1, F2, F3 with a correction distance E1, E2, E3 that is related to the displacement distance D1, D2 in a relationship that is defined by the cutting angle H. LIST OF REFERENCE NUMBERS drive unit rear conveyor front conveyor cutter measuring device i zcfrnn / zznz / E / YiAi first sensor second sensor control unit strip strip body first longitudinal edge second longitudinal edge front edge rear edge C cutting line D1 first lateral displacement distance D2 second lateral displacement distance D3 third lateral displacement distance E1 first correction distance E2 second correction distance E3 third correction distance F feed direction F1 first part of feed distance F2 second part of feed distance F3 third part of power distance H cutting angle L edge length (predefined) L1 reference distance L2 greater length L3 shorter length M measuring line P1 first lateral position detected P2 second lateral position detected R reference position X lateral direction And longitudinal direction

Claims

CLAIMS 1. A method for correcting a feed distance of a strip for cutting, wherein the strip has a strip body extending longitudinally, a first longitudinal edge extending on the first side of the strip body, and a second longitudinal edge extending on a second side of the strip body opposite the first side, wherein the method comprises the steps of: feeding the strip over the feed distance in a feed direction toward a cutting line extending at a cutting angle oblique to said feed direction; detecting a lateral position of the first longitudinal edge along a measuring line;Wherein, when the detected lateral position is displaced over a displacement distance in a lateral direction perpendicular to the feed direction with respect to a reference position for the first longitudinal edge on the measuring line, the method further comprises the step of: adjusting the feed distance with a correction distance that is related to the displacement distance in a proportion that is defined by the cutting angle.

2. Method according to claim 1, wherein the lateral position of the first longitudinal edge is detected on the measuring line upstream of the cutting line with respect to the feed direction.

3. Method according to claim 2, wherein the reference position is located on the measuring line at a reference distance from the cutting line in the feed direction, wherein the detected lateral position, when moved over the displacement distance, is at a greater or lesser distance from the cutting line in the feed direction than the reference distance, wherein the feed distance is adjusted by adding the correction distance to the reference distance in the case of a greater distance and subtracting the correction distance from the reference distance in the case of a lesser distance.

4. A method according to any one of the preceding claims, i zcfrnn / zznz / E / YiAi wherein the method comprises the steps of: comparing the detected lateral position with the reference position to determine the displacement distance; and calculating the correction distance in the feed direction using a trigonometric function with a first parameter indicative of the cutting angle and a second parameter indicative of the displacement distance as parameters; and adjusting the feed distance based on the calculated correction distance.

5. Method according to claim 4, wherein the trigonometric function is a tangent.

6. Method according to claim 5, wherein the trigonometric function is displacement distance correction distance = --------------------------tan 4 in which is the cutting angle.

7. Method according to claim 5, wherein the trigonometric function is tan 4 correction distance = --------------------------displacement distance in which is the equivalent of ninety degrees minus the cutting angle in degrees.

8. A method according to any one of claims 1-3, wherein a range of values ​​indicative of the correction distance associated with a range of lateral positions is stored in a database, wherein the method comprises the steps of: retrieving a value from the range of values ​​that is associated with a lateral position of the range of lateral positions that corresponds or substantially corresponds to the detected lateral position of the first longitudinal edge and using said value as the correction distance to adjust the feed distance.

9. Method according to any one of the preceding claims, wherein the reference position is a fixed position.

10. A method according to any one of claims 1-8, wherein the method comprises the steps of: cutting the strip at the cutting line to form a leading edge with respect to the feed direction; feeding the strip in the feed direction over the feed distance; and cutting the strip at the cutting line to form a trailing edge with respect to the feed direction; wherein the first longitudinal edge has an edge length in the feed direction between the leading edge and the trailing edge; and wherein, when the lateral position of the first longitudinal edge is displaced in the lateral direction at the trailing edge with respect to the leading edge, the feed distance is adjusted by the correction distance so that the edge length is constant or substantially constant regardless of said displacement.

11. Method according to claim 10, wherein the lateral position of the first longitudinal edge is detected at least twice along the length of the edge, wherein a first detected lateral position of the at least two detected lateral positions is used as a reference position to determine the displacement distance for a second detected lateral position of the at least two detected lateral positions.

12. Method according to claim 11, wherein the first detected lateral position is separated from the second detected lateral position in the feed direction over the length of the rim.

13. Method according to claim 11 or 12, wherein the first detected lateral position is the lateral position of the first longitudinal edge at the anterior edge and the second detected lateral position is the lateral position of the first longitudinal edge at the posterior edge.

14. A method according to any one of claims 10-13, wherein the method, prior to cutting the strip to form the leading edge, comprises the steps of: detecting a first lateral position of the first longitudinal edge on the measuring line upstream of the cutting line with respect to the feed direction; and feeding the strip over a first part of the feed distance that is corrected by the correction distance so that the first detected lateral position is located on the cutting line after feeding the strip over the first part of the feed distance.

15. A method according to claim 14, wherein the method, after cutting the strip to form the leading edge and before cutting the strip to form the trailing edge, comprises the steps of: feeding the strip over a second part of the feed distance that corresponds or substantially corresponds to the edge length less the first part of the feed distance; detecting a second lateral position of the first longitudinal edge on the measuring line; and feeding the strip over a third part of the feed distance that is corrected by the correction distance so that the second detected lateral position is located on the cutting line after feeding the strip over the third part of the feed distance.

16. A method according to any one of the preceding claims, wherein the lateral position of the first longitudinal edge is detected on the measuring line upstream of the cutting line with respect to the feed direction, wherein the cutting line converges to the measuring line at one of the first longitudinal edge and the other at the second longitudinal edge.

17. Method according to claim 16, wherein the cutting line is adjustable to extend at an alternative oblique cutting angle to the feed direction, wherein the cutting line converges towards the measuring line on the other side of the first longitudinal edge and the second longitudinal edge, wherein the steps of the method are performed relative to the second longitudinal edge instead of the first longitudinal edge when the cutting line extends at the alternative oblique cutting angle.

18. Method according to any one of the preceding claims, wherein the measuring line extends in the lateral direction perpendicular to the feed direction.

19. Apparatus for correcting a feed distance of a strip for cutting, wherein the strip has a strip body extending longitudinally, a first longitudinal edge extending on the first side of the strip body, and a second longitudinal edge extending on a second side of the strip body opposite the first side, wherein the apparatus comprises: a cutter for cutting the strip along a cutting line; a conveyor for feeding the strip along the feed distance in a feed direction toward the cutting line, wherein the cutting line extends at a cutting angle oblique to said feed direction; a drive for controlling the conveyor; a sensor device for detecting a lateral position of the first longitudinal edge along a measuring line;and a control unit that is operatively connected to the sensing device and the drive, wherein the control unit is configured to: adjust the feed distance when the detected lateral position is displaced over a displacement distance in a lateral direction perpendicular to the feed direction with respect to a reference position for the first longitudinal edge on the measuring line, wherein the feed distance is adjusted by a correction distance that is related to the displacement distance in a ratio that is defined by the cutting angle. i zcfrnn / zznz / E / YiAi; 20. Apparatus according to claim 19, wherein the measuring line is located upstream of the cut-off line with respect to the feed direction.

21. Apparatus according to claim 19 or 20, wherein the measuring line extends in the lateral direction perpendicular to the feed direction.

22. Apparatus according to any one of claims 19-21, wherein the sensing device comprises a first sensor for detecting the lateral position of the first longitudinal edge along the measuring line.

23. Apparatus according to claim 22, wherein the sensing device comprises a second sensor for detecting the lateral position of the second longitudinal edge, wherein the cutting line is adjustable to extend at an alternative oblique cutting angle to the feed direction, wherein the control unit is arranged to adjust the feed distance relative to the detected lateral position of the second longitudinal edge instead of the first longitudinal edge when the cutting line extends at the alternative oblique cutting angle.

Images