Method and straightening machine for straightening rod-shaped material

Abstract

The present invention relates to a method for straightening a non-straight rod-shaped material (1), the method being carried out by determining a target plastic deformation (s_soll) at a forming position (12) of the rod-shaped material (1) and moving a straightening hammer (8) with an integrated measuring probe (7) to the forming position (12), a first forming stroke (h_1) of the straightening hammer (8) is performed, an actual plastic deformation (s_ist) caused by the first forming stroke (h_1) is determined using the integrated measuring probe (7), and a second forming stroke (h_2) is determined from the actual plastic deformation (s_ist) caused by the first forming stroke (h_1) and the target plastic deformation (s_soll).

Description

[Technical Field]

[0001] The present invention relates to a method for straightening a non-linear rod of material by determining a target plastic deformation at a forming location of the rod of material.

[0002] The present invention also relates to a straightening machine for non-linear rod material for performing targeted plastic deformation at the forming location of the rod material using a control mechanism. [Background technology]

[0003] Bar-shaped material, such as pipes, profiles, or solid profiles, is processed in a cutting machine. Short sections are cut from a long length of material, which may be, for example, 12 meters long. These short sections may be, for example, 2 meters long.

[0004] Essentially, the pre-processed material is not perfectly straight. As a result, the cut length sections are also not perfectly straight. In the following, "perfectly straight" will also be referred to as "straight".

[0005] The straightness of the starting material depends on the material, production, material quality, the straightening process in the multi-roll straightener, transport, finishing, etc. A minimum straightness is often required for cut-to-length sections, for example for camshafts, engine shafts, or card shafts. As a rule, achieving perfect straightness in pre-processed material is technically impossible or prohibitively expensive.

[0006] The technique involves using a straightener to produce sections with the required straightness. Essentially, sections are measured for straightness, and any sections that fall outside a predetermined tolerance are sent to the straightener. The straightener then straightens the section and sends the straightened section back through the normal process sequence, where it can be checked for straightness again. Only those workpieces that achieve the required straightness before or after the straightening process are then output as good parts of the material stream.

[0007] In the prior art, straightening machines with a right-hand straightening anvil and a left-hand straightening anvil and one or more straightening hammers between them are known, for example from DE 10 2005 021 946 A1. First, the workpiece is clamped on both sides, for example center-to-center, and rotated and measured tactually or in a non-contact manner. A suitable computing unit calculates the straightness of the workpiece. The deviation profile is determined. The computing unit also calculates the deformations and support points required to achieve the straightness tolerance. Next, the workpiece is placed on the straightening anvils according to the precalculated target values ​​and plastically deformed with the straightening hammers until the workpiece achieves the required straightness.

[0008] To plastically deform the section, the straightening hammer must be used to exceed the elastic range of deformation. Only after elastic deformation does plastic deformation occur and remain permanently. The forming stroke of the straightening hammer must match the elastic deformation in addition to the plastic deformation. Again, when the straightening hammer relaxes the section, essentially the elastic deformation component rebounds and only the plastic deformation component remains in place. The amount of plastic deformation required at the forming position is known from the straightness measurement described above and the calculation of the straightness function in the calculation unit.

[0009] However, the problem arises that the function between the elastic and plastic parts of the forming stroke is not constant or does not follow a known correct function: it depends on many conditions such as residual stresses in the material, strain hardening, material variations, etc., which are not constant and therefore not predictable even within the length of the pre-processed material.

[0010] Thus, using measurements and mathematical calculations, it is known how much and where the workpiece needs to be deformed to achieve a specified tolerance, but it is not known how large the target stroke of the associated straightening hammer needs to be with certainty. Using statistical techniques, it is possible to predict the target stroke, but then there is also a significant probability that a significant amount of material will be plastically under- or over-deformed. Either the disadvantage is accepted, or the workpiece must again be lifted off the straightening anvil, measured, returned to the straightening anvil, and straightened again. This is disadvantageously very time-consuming. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] German Patent Application Publication No. 102005021946 [Non-patent literature]

[0012] [Non-Patent Document 1] Deep Learning with Python and Keras(ISBN978-3-95845-838-3) Summary of the Invention

[0013] Therefore, in a first aspect, it is an object of the present invention to provide a method for straightening a non-straight rod material that reduces at least the above-mentioned disadvantages.

[0014] Therefore, in a second aspect, it is an object of the present invention to provide a straightener for non-straight rod material that reduces at least the above-mentioned disadvantages.

[0015] In a first aspect, the object is met by a method having the features of claim 1.

[0016] First, one or more target plastic deformations are determined at one or more forming positions of the rod-shaped material by measurement and mathematical methods. Forming positions are understood here as positions or areas of the material where forming forces act to achieve the material deformation. Measurement and mathematical methods in this regard are state of the art and are known, for example, from Deep Learning with Python and Keras (ISBN 978-3-95845-838-3).

[0017] According to the present invention, a straightening hammer with an integrated measurement probe moves alongside or above the forming position. Integrated probe is generally understood to mean that the hammer and the integrated probe are connected to each other. The integrated probe is physically located on the straightening hammer, so that the probe is preferably located in the center of the pressure face of the straightening hammer. The pressure face of the straightening hammer contacts the forming position of the material during the forming process caused by the forming stroke.

[0018] A first forming stroke of the straightening hammer is performed and the actual plastic deformation caused by the first forming stroke is measured using the integrated measurement probe. If necessary, a second or further forming stroke is determined from the actual plastic deformation caused by the first forming stroke and the target deformation.

[0019] Preferably, to determine the first forming stroke, a characteristic diagram is provided that defines the actual plastic deformation range for the material for each possible forming stroke, within which the actual deformation has a high probability. Preferably, the maximum limit of the actual plastic deformation range is selected as the forming stroke. However, the forming stroke can also be selected within the upper 10%, 9%, or any lower value within the actual plastic deformation range.

[0020] This takes into account the fact that it is not possible to reliably predict which forming strokes will be required to achieve a given target plastic deformation at a forming location on the bar material. Rather, it is known from statistical methods, experience, and artificial intelligence and machine learning evaluations that a specific first forming stroke will result in deformation within the actual plastic deformation range, i.e., within the characteristic diagram.

[0021] The straightening hammer acts on the forming position in the first forming stroke. As a result, the bar material first becomes elastic and then deforms plastically. After releasing the straightening hammer, the elastic part rebounds and the actual state of plastic deformation is maintained. However, this cannot be reliably predicted during the specified first forming stroke.

[0022] However, since the actual deformation range is known, i.e., the actual deformation is realized within a certain range with a very high probability, i.e., 99% to 99.9% or more, for a particular forming stroke, the target deformation is conveniently selected as a high value, preferably as the maximum value of the actual deformation range.

[0023] This means that a target deformation is determined by known methods, the first forming stroke is assigned to the target deformation, and the actual deformation span is set to a maximum value that corresponds to the target deformation, i.e., is equal to the target deformation. However, in principle, other assignments are also possible. For example, the target deformation could be in the upper 1 / 10, 1 / 5, etc. of the actual deformation caused by the first forming stroke.

[0024] Advantageously, the first forming stroke provides elastic deformation of the material and actual deformation within the range of actual plastic deformation.

[0025] By conveniently and carefully selecting the first forming stroke, only in the best case will the actual deformation caused by the first forming stroke match the target deformation, and since the target deformation is at the maximum of the actual deformation range, the actual plastic deformation caused by the first forming stroke will in most cases be less than the target plastic deformation. Therefore, a second forming stroke is necessary.

[0026] The actual deformation caused by the first forming stroke is measured by the integrated measuring probe and evaluated together with the target deformation. Conveniently, a characteristic curve within the characteristic field range is determined by the actual deformation, and the characteristic curve is selected to determine the second forming stroke.

[0027] The method steps utilize the idea that the actual deformation cannot be predicted with certainty for a given forming stroke in a specific configuration, but only the range of the actual deformation recorded in the characteristic diagram can be defined. However, if the measurement data of the first deformation mentioned above are evaluated at the forming position where the actual deformation has already occurred, the actual deformation can be predicted very accurately by the second forming stroke.

[0028] It has been discovered that within the characteristic diagram, the characteristic curve can be determined quite precisely, or preferably quite accurately, for a specific forming position if the actual plastic deformation of the first forming stroke already performed is known for this forming position. Not only is the characteristic curve determined precisely by the zero point, but the actual deformation of the first forming stroke is performed and the characteristic curve is used according to the invention to determine the second forming stroke.

[0029] Advantageously, the characteristic curve defines the second forming stroke precisely, preferably exactly, with a defined target plastic deformation.

[0030] Preferably, the characteristic curve of the rod material within the characteristic diagram is determined from the actual deformation after the first forming stroke, which is traced through the zero point, and the measured actual deformation. The characteristic curve essentially has a comparable course within the characteristic diagram. Thus, the characteristic curve for the forming position can be determined with a single measurement.

[0031] A second shaping stroke is determined from the characteristic curve, the second shaping stroke corresponding to an intersection of the characteristic curve and the target deformation.

[0032] In a preferred embodiment of the process according to the invention, a target deformation of the bar material at the forming position is determined during the process using the integrated measuring probe. The bar material is clamped. The zero position of the straightening hammer is determined and stored. A first measurement value of the integrated measuring probe at the zero position of the straightening hammer is determined and stored. A first forming stroke of the straightening hammer is performed. The straightening hammer is then returned to the zero position, a second measurement value of the integrated probe at the zero position of the straightening hammer is determined, and the actual plastic deformation of the bar material resulting from the first forming stroke at the forming position is determined from the first and second measurements of the integrated probe.

[0033] Advantageously, the integrated probe only needs to determine a difference value between its first measurement and its second measurement, from which it can determine the actual plastic deformation caused by the first forming stroke. This can preferably be done by the integrated probe by determining the distance between the measuring head of the integrated probe and the forming location on the outer surface of the rod material in the first and second measurements, and creating a difference value from this value.

[0034] Preferably, a tolerance range is defined to determine the distance the rod may deviate from the straight rod, and if the difference between the actual deformation and the target deformation after the first forming stroke is outside the tolerance range, a second forming stroke is performed at the forming position. If necessary, a third and a fourth forming stroke can also be performed.

[0035] Preferably, the actual outer surface of the rod is first measured, and a deviation profile of the actual outer surface from a linear target outer surface is determined. The deviation profile is used to determine a forming location where the first forming stroke is applied. In addition to the forming location, typically one, two, or more contact points of the rod on the anvil are determined, as well as the distance between them.

[0036] The forming position is determined from the deviation profile as an angular position about the longitudinal direction of the bar material and also as a position along the axis of movement of the straightening hammer along the longitudinal direction of the straightener. The machine control mechanism then enables the bar material, preferably clamped between two holders, to be rotated about the longitudinal axis to the angular position determined from the deviation profile, and then moves the straightening hammer along the transverse axis alongside the bar material to advance in the longitudinal direction until the hammer is positioned directly at the forming position and can act against the forming position to perform a first forming stroke.

[0037] Conveniently, the target deformation is determined in a known manner from the deviation profile at the forming position, and the first forming stroke to be assigned to the target deformation is determined from the characteristic diagram, as explained above.

[0038] Conveniently, the rod material is placed on two anvils and the forming station is positioned longitudinally between the two anvils.

[0039] The object is solved in a second aspect thereof by a straightener having the features of claim 12.

[0040] The straightener is suitable for carrying out one of the processes described above, and conversely, the process described above is suitable for carrying out using one of the straighteners described below.

[0041] It is also believed that what is said about the method should be disclosed mutatis mutandis for the straightener.

[0042] The straightening machine according to the invention for non-linear rod-shaped material is also suitable for carrying out a targeted plastic deformation of the rod-shaped material at the forming position. The straightening machine comprises a control mechanism for a transverse device having a straightening hammer with an integrated measuring probe. The control system advantageously comprises a computing unit and a memory. A characteristic diagram defining the actual plastic deformation range for the material for each forming stroke is stored in the memory, and the actual deformation falls within this range with a high probability, i.e., more than 95%, 96%, preferably 99% or more.

[0043] Advantageously, the control unit, using its computing unit and advantageously with the aid of a characteristic diagram, determines the first forming stroke from the target deformation, which is preferably within the range of the top 10%, preferably the maximum value within the range of the actual deformation, although other arrangements between the range of the actual plastic deformation and the target plastic deformation are also conceivable.

[0044] Advantageously, the first forming stroke is selected such that for a given material, the actual plastic deformation performed by the first forming stroke is less than the determined target plastic deformation with a high probability of at least 95%, or more preferably 99% or more. Preferably, excessive deformation should be avoided.

[0045] The integrated measuring probe according to the present invention measures the actual plastic deformation caused by the first forming stroke and transmits the measured value to the control mechanism via a data communication connection. Due to the actual deformation actually determined for a specific forming position based on the actual forming stroke, the characteristic diagram can be limited to a characteristic curve. A characteristic curve within the characteristic diagram can be determined from the actual deformation. As explained above, the control system can then determine a second forming stroke from the target deformation and the characteristic curve. The second forming stroke is the value on the characteristic curve that generates the target deformation, i.e., after which the target deformation is ideally realized, or, if it still does not, at least a small amount of plastic deformation is realized, and the process cycle described above is performed a second time.

[0046] Preferably, the straightening machine comprises at least two anvils separated from each other in the longitudinal direction for supporting the rod-shaped material. The rod-shaped material can be preferably placed on the two anvils, whereby it is advantageously clamped by two holders, which are arranged opposite each other and rotatable. Between the two opposing holders, a measuring probe is advantageously arranged next to the clamped rod-shaped material, which measures the actual outer surface of the rod-shaped material and makes it possible to determine the deviation profile of the actual outer surface from a linear target outer surface. From this, as explained above, the forming position of the straightening hammer and the contact point of the rod-shaped material on the anvils can be determined by known methods.

[0047] Particularly preferably, the integrated measuring probe with the measuring head is guided centrally by the straightening hammer, whereby the measuring head enables distance measurements beyond the impact surface of the straightening hammer. Advantageously, the distance between the measuring head and the forming position of the rod-shaped material can be determined. Advantageously, a first distance measurement is performed before the first forming stroke is performed, and a second distance measurement is performed after the first forming stroke is performed, and these distance measurements are taken to determine the actual plastic deformation at the forming position caused by the forming stroke by subtracting them.

[0048] The straightening hammer is preferably arranged on an NC-controllable transverse axis transverse to the actual outer surface of the bar material, the NC-controllable transverse axis being very accurate and allowing the straightening hammer to be controlled in the micrometer range.

[0049] The rod-shaped material can advantageously be positioned on a receptacle, which can be a cone, however it is also conceivable that the receptacle can be shaped as just an empty area between two opposing holders, so that the holders can be, for example, two opposing ends in which the tube can be clamped and rotated.

[0050] The invention will now be explained using the example of an embodiment in six figures. [Brief explanation of the drawings]

[0051] [Figure 1] 1 is a schematic structure of a straightener according to the present invention for non-linear rod-shaped material. [Figure 2] 2 shows a straightening machine for the non-straight rod material of FIG. 1 in a first processing step. [Figure 3] 2 shows a straightening machine for the non-straight rod material of FIG. 1 in a second processing step. [Figure 4] 2 shows a straightening machine for non-straight rod material according to FIG. 1 in the third processing step. [Figure 5] 2 is a straightening machine for non-straight rod-shaped material according to FIG. 1 in a fourth processing step. [Figure 6] 1 is a diagram relating to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0052] The straightening machine 10 shown diagrammatically in Figures 1 to 5 and the process according to the invention carried out therein are used to straighten non-linear rod-shaped material. The rod-shaped material here means in particular a tube, a profile, a solid profile or the like extending along a longitudinal direction L, preferably of circular cross section, but which may also be angular, in particular rectangular.

[0053] The example embodiment refers to, but is by no means limited to, a tube 1. The tube 1 may have a length of several meters and a diameter of several centimeters or decimeters, although other dimensions are also possible.

[0054] At a glance, the tube 1 appears to be straight in the longitudinal direction L along its actual outer surface 11. On closer inspection, and this is the essence of the present invention, the tube 1 is not straight.

[0055] The pipe 1 shown in FIG. 1 is corrugated, for example, in the Y direction. The corrugations are not shown to scale here but are greatly exaggerated. Typically, the amplitude of the waves formed in the pipe is in the mm range, or less than 1-2 meters of pipe length. The waves extend along the longitudinal direction L, which here corresponds to the Z direction. Wave-like bulges can also occur in the X direction (not shown), which overlap the corrugations in the Y direction. The bulges do not have to have corrugations.

[0056] The tube 1 has an actual outer surface 11, which deviates from a linear target outer surface extending in the longitudinal direction L. A deviation profile can be determined along the longitudinal direction L by creating a difference between the actual outer surface and the target outer surface. For this purpose, the straightener 10 has a receptacle 16, on whose end faces the tool tips 5 and 6 are arranged to clamp the tube and rotate. The receptacle 16 preferably has a conical support surface for supporting the tube 1. Here, the receptacle 16 can be understood as the clearance between the two tool tips 5 and 6. The tool tips 5 and 6 can be individually moved back and forth along horizontal axes A and B, respectively, and both tool tips 5 and 6 are arranged in the Z direction. The tool tips 5 and 6 can also be individually moved in the XY plane of FIG. 1. In FIG. 1, a horizontal axis C is drawn relative to one tool tip 5, and a horizontal axis D is drawn relative to the other tool tip 6, both of which run in the Y direction. Two horizontal axes are not drawn in the X direction for the two tool tips 5, 6. Because the two tool tips 5, 6 are positioned opposite each other, their rotation axes run in extension of each other. By moving the tool tips 5, 6 towards each other, the tube 1 can be clamped between the tool tips 5, 6. By rotating the tool tips 5, 6, the clamped tube 1 itself can be rotated.

[0057] Along the receptacle 16 located between the tool tips 5, 6, the measuring probes 2 for measuring the straightness of the pipe 1 are arranged at fixed distances from each other along the longitudinal direction L. The distances may be equally spaced. Alternatively, different distances may be selected. The probes 2 may also be arranged at different angles in a cross section perpendicular to the longitudinal direction L around the receptacle 16 and the pipe 1. The measuring probes 2 may be tactile or optical, or may be designed in another way. The measuring probes enable distance measurements in a range with an accuracy of 0.1 μm or less. The measuring probes 2 for measuring the straightness of the pipe 1 are connected by data communication to a control system with a data memory, in which the measured distance values ​​for each measuring probe 2 and for the measuring points on the outer surface 11 of the pipe 2 are stored. As shown in FIG. 1 , the straightness of the tube 1 is measured as the tube 1 is clamped, and the measurement probe 2 performs a first distance measurement, the tube 1 is rotated a short distance by angles α and β, the measurement probe 2 performs a second distance measurement at the rotated angular position, the tube 1 is rotated a further angle α and β, and the measurement probe 2 performs a third distance measurement, etc. The distance measurements, along with the position of the probe 2 along the longitudinal direction L and the angular position, are stored and evaluated to determine the actual outer surface 11 of the tube 1. The actual outer surface 11 of the tube 1 deviates from the target outer surface of a straight tube 1. In FIG. 1 , the tube 1 is shown with an exaggerated curvature.

[0058] Typically, deviations from straightness to a predetermined tolerance of 1 μm or less are tolerated for further processing of the tube 1. Non-straightness outside the tolerance range is classified and straightened according to the invention. The tube 1 is straightened by the straightener 10 according to the invention and brought back within the tolerance range.

[0059] Straightening of the tube 1 is preferably carried out with the aid of two anvils 3, 4 shown diagrammatically in Figure 1 and using a straightening hammer 8 according to the invention, in which an integrated measuring probe 7 is centrally arranged. The straightening hammer 8 is a cylindrical structure with a central bore, preferably a central circular bore, in which the tactile or optical integrated measuring probe 7 is preferably integrated. The integrated measuring probe 7 can move back and forth relative to the straightening hammer 8 along a vertical movement axis J within the straightening hammer 8 and can be hidden by the straightening hammer 8, with the measuring surface 7a aligned with the striking surface 8a of the straightening hammer 8.

[0060] The integrated measuring probe 7 is mounted on the straightening hammer 8 together with a return spring 15 which pushes the measuring surface 7a outwards from the striking surface 8a in an unloaded state.

[0061] According to Figure 1, the straightening hammer 8 can be moved towards and away from the tube 1 along a vertical transverse axis H, and can be moved along a horizontal transverse axis G along the longitudinal direction L of the tube 1, and can also be moved along a horizontal transverse axis (not shown) perpendicular to the longitudinal direction L. As shown in Figure 1, the measuring surface 7a of the measuring probe 7 can also be moved parallel to the transverse axis H of the straightening hammer 8, preferably very easily, i.e. with little resistance.

[0062] Figure 2 shows the arrangement of the straightening hammer 8, the measuring probe 7, as well as the two anvils 3, 4 and the tube 1 clamped between the tool tips 5, 6 just before straightening. The two anvils 3, 4 can move back and forth along the longitudinal direction L along the transverse axes E, F.

[0063] From the actual deviation profile of the tube 1 from the target outer surface, the forming position 12 of the straightening hammer 8 on the tube 1 and the support points 13, 14 of the tube 1 on the anvils 3, 4 are calculated, and thus the positions of the horizontal axis G and angles α, β of the two angle tips 5, 6 and the required target deformation of the tube 1 at the forming position 12 are calculated, which calculation is performed to straighten the tube when it is supported between two anvils 3, 4 separated by a certain distance from each other.

[0064] The problem arises that the target deformation of the forming position 12 of the tube 1 and the forming stroke h of the straightening hammer 8 cannot be clearly assigned to one another.

[0065] The straightening process of the prior art is essentially always the same. To plastically deform the tube 1, first the straightening hammer 8 must apply a forming stroke h to the tube 1, exceeding the elastic range of deformation. Only after the elastic deformation does the plastic deformation s occur. The forming stroke h of the straightening hammer 8 must essentially correspond to the elastic deformation in addition to the plastic deformation s. Again, when the straightening hammer 8 retracts and the tube 1 becomes unloaded, the elastic deformation component essentially bounces back, and only the plastic deformation component remains, which now also corresponds to the actual plastic deformation s_ist.

[0066] In principle, to achieve sufficient straightening of the tube 1 by straightening, it is necessary to know how large the plastic deformation s is at the forming position 12. However, it is known that there is no function between the elastic and plastic deformation components of the forming stroke h. The function between the elastic and plastic deformation components depends on many conditions, particularly material properties, work hardening, and other material changes. However, because they are very different, the function between the elastic and plastic parts is unpredictable even within the length of the tube 1. Therefore, it is not known with certainty, and the forming stroke h must be performed with the straightening hammer 8 to achieve the target deformation s_soll. Using statistical methods, possible forming strokes h can be predicted, and then there is a fairly high probability that the tube 1 will be plastically over- or under-deformed. If over-forming occurs, the tube 1 will need to be remeasured, the anvils 3 and 4 will be lifted, the tube 1 will be rotated and placed back down, and the tube will be straightened again. This takes time.

[0067] Figure 6 shows a schematic representation of the procedure implemented in Figures 2, 3, 4, and 5. Figure 6 first shows a given characteristic diagram 60, which can be obtained using statistical methods related to artificial intelligence, machine learning, etc., such as Deep Learning with Python and Keras (ISBN 978-3-95845-838-3). The statistical relationship between the forming stroke h of the straightening hammer 8 and the plastic deformation s generated by the forming stroke h for a specific material is shown. The distance between the two anvils 3 and 4 and the position of the straightening hammer 8 is also included in the characteristic diagram 60. When the first forming stroke h_1 is performed, the characteristic diagram 60 is interpreted so that the actual plastic deformation s_ist falls within the deformation span b along the X-axis within the characteristic diagram 60. The actual plastic deformation s_ist falls within the deformation span b with a probability of 95%, 99%, or 99.9%. The width of the characteristic diagram 60, i.e., the length of the deformation span b in the X-direction, primarily depends on the material properties. Its width depends in particular on the residual stresses, strain hardening or other material variations of the material. On the other hand, the spherical shape of the characteristic curve 60 also depends on the distance at which the anvils 3, 4 are separated from one another, the diameter of the tube 1, the wall thickness of the tube 1, etc., which are all parameters that make it possible to predict the correct bending behavior and therefore do not significantly influence the width of the characteristic curve 60. They only influence the spherical shape, i.e., the slope of the characteristic curve 60, etc.

[0068] Furthermore, it is known that the actual deformation s_ist of the rod-shaped material, in particular the tube 1, subjected to different first forming strokes h at the forming position 12 follows a characteristic curve 61 moving within a characteristic diagram 60 shown in Figure 6. The characteristic curve 61 is inserted within the characteristic diagram 60. It has been found that the characteristic curve 61 within the characteristic diagram 60 can also be precisely defined in real units by two points.

[0069] The process according to the invention proceeds as described below.

[0070] The tube 1 is positioned on the anvils 3, 4 at specific angles α, β according to the known method of Fig. 2. The forming position 12 of the straightening hammer 8 and the support points 13, 14 on the anvils 3, 4 are known. In a first process step according to Fig. 2, the straightening hammer 8 is positioned above the forming position 12 with a horizontal axis G. The straightening hammer 8 is positioned on the anvils 3, 4. In order to be able to provide a tube 1 that is as straight as possible after the straightening process, it is necessary to know how large the target plastic deformation s_soll at the forming position 12 is.

[0071] In the second processing step, as shown in FIG. 3, the straightening hammer 8 moves along the horizontal axis H toward the forming position 12 of the tube 1 until the measuring surface 7a of the probe 7 touches the outer surface of the tube 1. However, the probe 7 does not apply any pressure to the forming position 12, which would have already bent the tube. The straightening hammer 8 returns to the zero position. The zero position is determined, and its coordinates are recorded. Here, a first measurement is performed by the measuring probe 7 at the zero position, and the first measurement value of the measuring probe 7 is stored. For example, the measurement data is recorded in terms of the distance that the measuring surface 7a of the measuring probe is away from the striking surface 8a in the Y direction, or a similar measurement value. The first measurement value is a measurement that determines the distance between the forming position 12 and the striking surface 8a of the straightening hammer 8. However, this does not have to be the case; it is important to record only the position of the forming position 12 relative to the straightening hammer 8.

[0072] In a third process step, a first forming stroke h_1 is applied to the forming position 12, as shown in FIG.

[0073] The first forming stroke h_1 is determined in advance from the known target deformation s_soll at the forming position 12. For this purpose, the intersection point between the target deformation s_soll and the lower minimum of the characteristic diagram 60 is determined according to FIG. 6. From the intersection point, the first forming stroke h_1 is determined. The selected first forming stroke h_1 statistically generates the target deformation s_soll within the deformation span b for the material. Through the first forming stroke h_1, the target deformation s_soll is only realized in the best case. If this is not realized, an actual deformation s_ist occurs, which is lower than the target deformation s_soll within the deformation span b. Therefore, the tube 1 deforms less than it should actually deform.

[0074] The deformation process is carried out by a straightening hammer 8 rigidly mounted on an NC-controllable axis H, as shown in Figure 4. The straightening hammer 8 moves in the opposite direction to the Y direction with a first forming stroke h_1. The straightening hammer 8 moves in the opposite direction to the Y direction with an NC-controllable axis H with a first forming stroke h_1, as shown in Figure 4, and bends the tube 1 to a certain extent, as shown in Figure 4. The bend includes an elastic part and a plastic part.

[0075] In Figure 5, the straightening hammer 8 is again retracted, and the elastic deformation weakens. The state of plastic deformation continues, straightening the tube 1.

[0076] The information acquisition according to the invention is carried out by means of the measuring probe 7. Then, in a fourth processing step, according to Fig. 5, the straightening hammer 8 is retracted, the tube 1 is relaxed, according to Fig. 3, the straightening hammer 8 returns to the zero position, and a second measurement is carried out with the measuring probe 7 to determine a second measured value. The second measured value is compared with the first measured value of the measuring probe 7, and from the difference in the measurements, for example from the difference in the distance from the striking face 8a of the straightening hammer 8 to the forming position 12, the actual deformation s_ist is determined after the first forming stroke h_1.

[0077] The idea of ​​the present invention is to make it possible to execute the second forming stroke h_2 very accurately and to narrow the range of the characteristic diagram 60 considerably using information about the first actual deformation s_ist in order to bring it very close to the target deformation s_soll.

[0078] The actual plastic deformation s_ist after the first forming stroke h_1 usually does not match the target plastic deformation s_soll but is lower than the target deformation s_soll. However, the measurement by the measuring probe 7 allows the absolute value of the actual deformation s_ist generated by the first forming stroke h_1 to be shown. As a result, according to FIG. 6, the actual deformation s_ist can be assigned to the first forming stroke h_1, and thus the characteristic curve 61 within the characteristic curve 60 of FIG. 6 can be assigned to the forming position 12 with its specific material properties. The characteristic curve 61 shows the plastic deformation behavior at different strokes h for the forming position 12.

[0079] In a further process loop, according to Figures 3, 4 and 5, the tube 1 is straightened at the forming position 12 with a second forming stroke h_2, the size of which is determined from the characteristic curve 61 in Figure 6 and its intersection with the target deformation s_soll.

[0080] If necessary, the process loop can also be performed three or four times. Actual implementations of the process have shown that several process loops are required. However, this process has also shown to be able to iteratively approach the target deformation s_soll and maintain the specified straightness tolerance with a high degree of accuracy. [Explanation of symbols]

[0081] 1. Tube / rod-shaped materials 2 probes 3 Anvil 4 Anvil 5 Tool tip 6 Tool Tip 7 7a Measuring surface 8 Judging Hammer 8a Stroke surface 10 Orthodontic device 11 Actual surface 12 Molding position 13 Support points 14 Support points 15. Expansion spring 16 receptacles 60 known fields 61 Feature lines b Deformation span h forming stroke h_1 First forming stroke h_2 Second forming stroke s Plastic deformation s_ist plastic deformation s_soll target deformation A moving axis B Movement axis C Movement axis D Movement axis E Movement axis F moving axis G Vertical movement axis H Horizontal movement axis J moving axis L Vertical α angle β angle

Claims

1. A method for straightening a non-straight rod-shaped material (1), comprising the steps of: A target plastic deformation (s_soll) is determined at a forming position (12) of the non-linear rod-shaped material (1); A straightening hammer (8) with an integrated measuring probe (7) moves into said forming position (12), a characteristic diagram (60) is provided showing the plastic deformation span (b) for the non-linear rod-shaped material per forming stroke (h); a first forming stroke (h_1) of the straightening hammer (8) is carried out, the actual plastic deformation (s_ist) caused by said first forming stroke (h_1) is determined using said integrated measurement probe (7), a characteristic curve (61) of the non-linear rod-shaped material (1) within the characteristic diagram (60) is determined from the actual deformation (s_ist) after the first forming stroke (h_1), and a second forming stroke (h_2) is determined from the characteristic curve (61), the second forming stroke (h_2) corresponding to the forming stroke (h) for the target plastic deformation (s_soll) along the characteristic curve (61).

2. 2. The method of claim 1, wherein the target plastic deformation (s_soll) within the top 10% of the plastic deformation span (b) is selected as the maximum value of the plastic deformation span (b) of the first forming stroke (h_1).

3. 3. The method according to claim 1, wherein the elastic deformation of the non-linear rod-shaped material within the plastic deformation span (b) and the actual plastic deformation (s_ist) are performed by the first forming stroke (h_1).

4. 4. The method according to claim 1, wherein the first forming stroke (h_1) is selected such that the associated plastic deformation span (b) has a maximum value corresponding to the target plastic deformation (s_soll), and the actual deformation (s_ist) caused by the first forming stroke (h_1) defines a characteristic curve (61) within the characteristic diagram (60), and the characteristic curve (61) is selected for determining the second forming stroke (h_2).

5. The target plastic deformation (s_soll) is determined at the forming position (12) of the non-linear rod-shaped material (1); The non-linear rod-shaped material (1) is clamped, The zero position of the straightening hammer (8) is determined, a first measurement value of the integrated measuring probe (7) is determined at the zero position of the straightening hammer (8); The first forming stroke (h_1) of the straightening hammer (8) is carried out, The straightening hammer (8) returns to the zero position, 5. The method according to claim 1, wherein a second measurement value of the integrated measuring probe (7) is determined at the zero position of the straightening hammer (8), the actual plastic deformation (s_ist) of the non-linear rod-shaped material (1) due to the first forming stroke (h_1) is determined from the first measurement value and the second measurement value, and the actual plastic deformation (s_ist) is compared with the target plastic deformation (s_soll).

6. 6. The method according to claim 1, wherein a tolerance range is defined and, if, after the first forming stroke (h_1) has been performed, the difference between the actual deformation (s_ist) and the target plastic deformation (s_soll) is outside the tolerance range, the second forming stroke (h_2) is performed at the forming position (12).

7. An actual outer surface of the non-linear rod-shaped material (1) is measured, and a deviation profile of the actual outer surface from a linear target outer surface is determined; Method according to any one of claims 1 to 6, characterized in that the forming position (12) is determined from the deviation profile.

8. 8. The method according to claim 7, characterized in that the forming position (12) is determined from the deviation profile as an angle (α, β) centered on the longitudinal direction (L) of the non-linear rod-shaped material (1) and is also determined as a position along the longitudinal direction (L) and along the movement axis (G) of the straightening hammer (8).

9. 9. The method according to claim 8, characterized in that the non-linear rod-shaped material (1) is placed on two anvils (5, 6) spaced apart from each other, and the forming position (12) is arranged between the two anvils (5, 6) in the longitudinal direction (L).

10. A straightening machine for a non-linear rod-shaped material (1) for performing a target plastic deformation (s_soll) at a forming position (12) of the non-linear rod-shaped material (1), comprising: a control mechanism for a crossing device having a straightening hammer (8) with an integrated measuring probe (7); a memory for a characteristic diagram (60) showing the actual plastic deformation span (b) of said non-linear rod-shaped material for each forming stroke (h); Thereby, a first forming stroke (h_1) can be determined from the target plastic deformation (s_soll) through the control mechanism, measuring the actual plastic deformation (s_ist) caused by said first forming stroke (h_1) through said integrated measuring probe (7) and feeding the measured values ​​to said control mechanism via a data communication connection; A characteristic curve (61) within the range of the characteristic diagram (60) can be determined from the actual deformation (s_ist) of the control mechanism, A straightening machine, characterized in that a second forming stroke (h_2) can be determined by said control mechanism from said target resuscitation deformation (s_soll) and said characteristic curve (61).

11. 11. A straightening machine according to claim 10, characterized by at least two anvils (3, 4) spaced apart from each other in a longitudinal direction (L) for supporting the non-linear rod-shaped material (1).

12. 12. A straightening machine according to claim 10 or 11, characterized in that the integrated measuring probe (7) with a measuring head (7a) is guided centrally by the straightening hammer (8), the measuring head (7a) enabling distance measurements beyond the impact surface (8a) of the straightening hammer (8).

13. 13. A straightening machine according to claim 12, characterized in that the integrated measuring probe (7) is a tactile measuring probe, the measuring head (7a) of the integrated measuring probe (7) protruding centrally from the bore of the straightening hammer (8) and being able to return completely inside behind the impact surface (8a) of the straightening hammer (8).

14. The straightening machine according to any one of claims 10 to 13, characterized in that the straightening hammer (8) is arranged on a horizontal axis (H) that can be controlled by NC in the transverse direction of the actual outer surface of the non-linear rod-shaped material.

15. A straightening machine according to any one of claims 10 to 14, characterized in that a measuring system for measuring the outer surface of the non-linear rod-shaped material (1) is arranged along the receptacle (16) for the non-linear rod-shaped material (1).

16. 16. The straightening machine according to claim 15, characterized in that the measuring system comprises rotatable holders (5, 6) arranged oppositely to clamp the non-linear rod-shaped material (1), and a measuring probe (2) arranged between the rotatable holders (5, 6) and positioned next to the clamped non-linear rod-shaped material (1).

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