Method for straightening bar-shaped material and a straightening machine

Description

[0001] The invention relates to a method for straightening non-straight, rod-shaped material by determining a desired plastic deformation at a forming position of the rod-shaped material.

[0002] The invention also relates to a straightening machine for non-straight, rod-shaped material for carrying out a desired plastic deformation at a forming position of the rod-shaped material with a control system.

[0003] Cutting machines process rod-shaped materials, such as pipes, profiles, and solid sections. The long raw material, which can be up to 12 meters long, is cut into shorter sections. These shorter sections can be up to two meters long, for example.

[0004] Generally, the raw materials are not exactly straight. This means that the cut sections are not exactly straight either. In the following, "exactly straight" will also be referred to as "straight."

[0005] The straightness of the raw material depends on the material, the manufacturing process, the material quality, the straightening processes on multi-roll straightening machines, transport, post-processing, and much more. A minimum straightness is often required for the cut sections, for example, for sections for camshafts, engine shafts, or cardan shafts. It is usually technically impossible or extremely complex to achieve straightness in the raw material itself.

[0006] Straightening machines are used to produce the sections with the required straightness. The sections are measured for straightness, and any sections that fall outside a specified tolerance are sent to the straightening machine. The straightening machine then straightens the sections and returns the straightened sections to the normal process flow, where their straightness can then be checked again. Only those workpieces that achieve the required straightness before or after the straightening process are then released into the material flow as approved parts.

[0007] In the prior art, for example, DE10 2005 021 946 A1 discloses straightening systems with a straightening anvil on the right and a straightening anvil on the left, with one or more straightening hammers in between. First, the workpiece is clamped on both sides, for example, between centers, and measured using rotating, tactile, or non-contact methods. A suitable processing unit calculates the straightness of the workpiece. A deviation profile is determined. The processing unit also calculates the necessary deformations and support points to achieve the straightness tolerance. The workpiece is then placed on the straightening anvils according to the previously calculated target values ​​and plastically deformed with the straightening hammer until the workpiece achieves the required straightness.

[0008] To plastically deform the section, it is necessary to exceed the elastic deformation range with the straightening hammer. Only after elastic deformation does plastic deformation occur, and this deformation remains permanently. The forming stroke of the straightening hammer must correspond to the elastic deformation plus the plastic deformation. When the straightening hammer releases the load from the section, the elastic deformation component essentially rebounds, leaving only the plastic deformation component. The desired plastic deformation at the forming position is known from the previous straightness measurements and the calculation of the straightness function in the calculation unit.

[0009] The problem, however, is that the function between the elastic and plastic components of the forming stroke is not constant, or rather, does not obey a precisely known function. This function depends on many conditions, such as residual stresses in the material, strain hardening, and material fluctuations, which, however, are not constant even within the length of the starting material and therefore cannot be predicted.

[0010] Thus, through measurement and mathematical calculation, it is known how much and where the workpiece must be deformed to achieve the specified tolerance, but it is not known how large the corresponding target stroke of the straightening hammer must be. Statistical methods make it possible to predict the target stroke, but there is then a significant probability that the material will be plastically deformed too little or too much. This disadvantage is either accepted, or the workpiece is lifted off the straightening anvils again, measured, placed back on the straightening anvils, and straightened again. Unfortunately, this is very time-consuming.

[0011] US Pat. No. 3,481,170 describes a straightening method in which successive strokes are performed, with the lengths of the strokes corresponding to the workpiece's eccentricities previously determined by measurement. The strokes are performed one after the other until the eccentricity is within a specified tolerance. The disadvantage of this method is that a relatively large number of strokes must be performed to achieve a satisfactory result.

[0012] DE 32 11 489 A1 also discloses a method for correcting deviations from the desired shape of plastically deformable objects. After the first straightening process, the object's shape is measured again, and any remaining shape errors are identified. The relationship between the correction length and the magnitude of the shape deviation is then adjusted depending on the measured residual shape errors in order to improve the straightening of the next object. It is taken into account whether a so-called over- or teaching-over has occurred, i.e., whether the shape correction was too large or too small. This creates an adaptive shape correction method.

[0013] From CN 113828656 A a measuring probe is known which is arranged on a straightening hammer.

[0014] It is therefore an object of the invention in a first aspect to provide a method for straightening non-straight, rod-shaped material which at least reduces the above disadvantages.

[0015] In a second aspect, it is an object of the present invention to provide a straightening machine for non-straight, rod-shaped material which reduces the above disadvantages.

[0016] The object is achieved in its first aspect by a method having the features of claim 1.

[0017] First, one or more target plastic deformations are determined at one or more forming positions of the rod-shaped material using measurement and mathematical methods. The forming position here refers to the position or area on the material to which a forming force is applied in order to achieve a deformation of the material. The measurement and mathematical methods used are state-of-the-art and are known, for example, from deep learning with Python and Keras (ISBN 978-3-95845-838-3).

[0018] According to the invention, a straightening hammer with an integrated measuring probe is moved next to or onto the forming position. An integrated measuring probe is generally understood here to mean that the straightening hammer and the integrated measuring probe are connected to each other. The integrated measuring probe is physically arranged in the straightening hammer, preferably in the center of a pressure surface of the straightening hammer. The pressure surface of the straightening hammer encounters the forming position of the material during the forming process caused by the forming stroke.

[0019] The straightening hammer performs a first forming stroke, and the actual plastic deformation resulting from the first forming stroke is measured using the integrated measuring probe. Based on the actual plastic deformation resulting from the first forming stroke and the target deformation, a second forming stroke or additional strokes are determined, if necessary.

[0020] According to the invention, a characteristic map is provided to determine the first forming stroke. This map specifies an actual plastic deformation range for the material for each possible forming stroke, within which the actual deformation lies with 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.

[0021] This takes into account the fact that for a given target plastic deformation to be performed at the forming position of the rod-shaped material, it is not possible to reliably predict which forming stroke must be performed. Rather, it is known through statistical methods, empirical values, and evaluation by artificial intelligence and machine learning that a specific first forming stroke produces deformations within an actual plastic deformation range, i.e., within the characteristic map.

[0022] The straightening hammer applies an initial forming stroke to the forming position. This causes the rod-shaped material to undergo elastic and then plastic deformation. After the straightening hammer is released, the elastic portion rebounds, leaving the actual plastic deformation. However, this cannot be reliably predicted for the specified initial forming stroke.

[0023] However, since the actual deformation range is known, i.e. which actual deformation within a certain range is achieved by a certain forming stroke with a very high probability, i.e. 99% - 99.9% or higher, the target deformation is advantageously selected as a high value, preferably as the maximum value of the actual deformation range.

[0024] This means that the target deformation is determined using known methods, and the first forming stroke is assigned to the target deformation whose actual deformation range is designed such that its maximum value corresponds to, i.e., is equal to, the target deformation. However, other assignments are also conceivable. For example, the target deformation can be in the upper tenth, fifth, etc., of the actual deformations generated by the first forming stroke.

[0025] Advantageously, the first forming stroke results in elastic deformation of the material and actual deformation within the actual plastic deformation range.

[0026] Since the first forming stroke is advantageously carefully selected in such a way that the actual deformation generated by the first forming stroke only corresponds to the target deformation in the best case scenario, and the target deformation is the maximum value of the actual deformation range, in the vast majority of cases the actual plastic deformation generated by the first forming stroke will be below the target plastic deformation. Therefore, a second forming stroke is required.

[0027] The actual deformation generated by the first forming stroke is measured by the integrated measuring probe and evaluated together with the target deformation. Ideally, a characteristic curve within the characteristic field is defined by the actual deformation, and this characteristic curve is selected to determine the second forming stroke.

[0028] This process step utilizes the idea that the actual deformation for a given forming stroke in a specific configuration cannot be reliably predicted, but only an actual deformation range can be specified, which is defined in the characteristic map. However, the actual deformation can be predicted much more precisely by a second forming stroke if the measurement data from a previous first deformation are evaluated at the forming position for which an actual deformation has already been performed.

[0029] It has been found that within the characteristic map, a characteristic curve can be determined quite accurately, or preferably very accurately, for a specific forming position if the actual plastic deformation for a first forming stroke already performed is known for this forming position. The characteristic curve is precisely determined by the zero point and the actual deformation during the first forming stroke, and according to the invention, it is used to determine the second forming stroke.

[0030] Advantageously, the characteristic curve specifies the second forming stroke at the specified plastic target deformation more precisely, preferably exactly.

[0031] According to the invention, a characteristic curve of the rod-shaped material is determined from the actual deformation after the first forming stroke within the characteristic field, passing through the zero point and the measured actual deformation. The characteristic curves generally have a comparable course within the characteristic field. Therefore, the characteristic curve for the forming position can be determined from a single measurement.

[0032] The second forming stroke is determined from the characteristic curve. The second forming stroke corresponds to the intersection point of the characteristic curve with the target deformation. In a preferred embodiment of the method according to the invention, the target deformation is determined at a forming position of the rod-shaped material during the process using the integrated measuring probe. The rod-shaped material is clamped. A zero position of the straightening hammer is determined and stored. A first measured value of the integrated measuring probe in the zero position of the straightening hammer is determined and stored. The first forming stroke of the straightening hammer is carried out.Then the straightening hammer is returned to the zero position, and a second measured value of the integrated measuring probe is determined in the zero position of the straightening hammer, and from the first and second measured values ​​of the integrated measuring probe, an actual plastic deformation of the rod-shaped material by the first forming stroke at the forming position is determined.

[0033] Advantageously, the integrated measuring probe only needs to determine a difference value in its first and second measurements, from which the actual plastic deformation resulting from the first forming stroke can be determined. This can preferably be achieved by the integrated measuring probe determining a distance between a measuring head of the integrated measuring probe and the forming position on the outer surface of the rod-shaped material in a first and a second measurement and calculating a difference value from this.

[0034] Preferably, a tolerance range is specified that determines how far the rod-shaped material may deviate from the straight rod-shaped material. If, after performing the first forming stroke, the difference between the actual plastic deformation and the desired plastic deformation at the forming position lies outside the tolerance range, a second forming stroke is performed at the forming position. If necessary, a third and fourth forming stroke can also be performed.

[0035] Preferably, the actual outer surface of the rod-shaped material is first measured, and a deviation profile of the actual outer surface from a straight target outer surface is determined. From the deviation profile, the forming position at which the first forming stroke is applied is determined. In addition to the forming position, one, two, or more support points of the rod-shaped material on anvils and their distance are usually determined.

[0036] The forming position is determined from the deviation profile and as an angular position around the longitudinal axis of the bar-shaped material, and as a position along a travel axis of the straightening hammer along the longitudinal direction of the straightening machine. The machine's control system then allows the bar-shaped material, preferably clamped between two holders, to be rotated around its longitudinal axis into the angular position determined from the deviation profile. The hammer is then moved alongside the bar-shaped material along a travel axis running in the longitudinal direction until the straightening hammer is positioned directly on the forming position and can act on the forming position to execute the first forming stroke.

[0037] Advantageously, a target deformation is determined in a known manner from the deviation profile at the forming position and the first forming stroke, which is assigned to the target deformation, is determined from the characteristic map as described above.

[0038] Advantageously, the rod-shaped material is placed on two anvils spaced apart from each other and the forming position is arranged in the longitudinal direction between the two anvils.

[0039] The problem is solved in its second aspect by a straightening machine having the features of claim 9.

[0040] The straightening machine is suitable for performing one of the above-mentioned processes. Conversely, the above-mentioned processes are suitable for performing with one of the straightening machines described below.

[0041] What has been said with regard to the method is also deemed to be disclosed mutatis mutandis for the straightening machine.

[0042] The straightening machine according to the invention for a non-straight, rod-shaped material is suitable for performing a desired plastic deformation at a forming position of the rod-shaped material. It comprises a control system for a traversing device with a straightening hammer with an integrated measuring probe. The control system advantageously comprises a processing unit and a memory. A characteristic map is stored in the memory, which specifies an actual deformation range for the material for each forming stroke, within which the actual deformation lies with a high probability, i.e., more than 95%, 96%, preferably 99% or more.

[0043] The control system advantageously uses its computing unit to determine the first forming stroke from the target deformation, preferably with the aid of the characteristic map. The target deformation is preferably within the upper 10% or less, preferably a maximum value within the actual deformation range. However, other arrangements between the actual plastic deformation range and the target plastic deformation are also conceivable.

[0044] Advantageously, the first forming stroke is selected such that, for the given material, the first forming stroke results in an actual plastic deformation that is below the specified target plastic deformation, at least with a high probability of 95% or more, preferably 99% or more. Overdeformation should preferably be avoided.

[0045] The integrated measuring probe according to the invention measures the actual plastic deformation resulting from the first forming stroke and transmits the measured values ​​to the control system via a data connection. The actual deformation actually determined for the specific forming position on the basis of the actual forming stroke allows the characteristic map to be restricted to a characteristic curve. A characteristic curve within the characteristic map can be determined from the actual deformation. The control system can then, as described above, 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 produces the target deformation, i.e., after its execution, the target deformation is ideally achieved or, if this is not yet the case, at least only a slight plastic under-deformation is achieved and the process cycle described above is run through again.

[0046] The straightening machine preferably comprises at least two anvils spaced apart from one another in a longitudinal direction for supporting the rod-shaped material. The rod-shaped material can preferably be placed on the two anvils and can advantageously be clamped by two holders that are opposite one another and arranged for rotation. Measuring probes are advantageously arranged between the two opposing holders. These probes are arranged next to the clamped, rod-shaped material and allow the actual outer surface of the rod-shaped material to be measured and a deviation profile of the actual outer surface from the straight desired outer surface to be determined. From this, the forming position for the straightening hammer and the support points of the rod-shaped material on the anvils can then be determined using known methods, as described above.

[0047] Particularly preferably, the integrated measuring probe with a measuring head is guided centrally through the straightening hammer, whereby the measuring head enables distance measurement beyond a striking 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 and a second distance measurement is performed after the first forming stroke in order to determine the actual plastic deformation at the forming position caused by the forming stroke by calculating the difference.

[0048] The straightening hammer is preferably mounted on an NC-controlled travel axis perpendicular to the actual outer surface of the bar-shaped material. NC-controlled travel axes are very precise and allow the straightening hammer to be controlled within micrometers.

[0049] The rod-shaped material can be conveniently positioned on a holder. The holder can be conical. However, it is also conceivable for the holder to be formed merely as a clear area between two opposing holders. The holders can, for example, be two opposing points between which the tubes are clamped and can be rotated.

[0050] The invention is described using an exemplary embodiment in six figures. These show: Fig. 1 a schematic structure of a straightening machine according to the invention for non-straight, rod-shaped material, Fig. 2 the straightening machine for non-straight, rod-shaped material of the Figure 1 in a first process step, Fig. 3 the straightening machine for non-straight, rod-shaped material of the Figure 1 in a second process step, Fig. 4 the straightening machine for non-straight, rod-shaped material according to Figure 1 In a third process step, Fig. 5, the straightening machine for non-straight, rod-shaped material according to Figure 1 in a fourth process step, Fig. 6 a characteristic map.

[0051] One in the Figures 1 to 5 The schematically illustrated straightening machine 10 and the method according to the invention performed on the straightening machine 10 are used for straightening non-straight, rod-shaped material. Rod-shaped material is understood here to mean, in particular, tubes, profiles, solid profiles, etc. extending along a longitudinal direction L, which can preferably have a circular cross-section, but also be angular, in particular square.

[0052] The exemplary embodiment refers to a pipe 1, but is not limited to this in any way. The pipe 1 can have a length of several meters and a diameter of several centimeters or decimetres. Other dimensions are also conceivable.

[0053] At first glance, the tube 1 appears straight in the longitudinal direction L along its actual outer surface 11. Upon closer inspection, and this is the point of this invention, the tube 1 is not straight.

[0054] The Figure 1 The pipe 1 shown, for example, is undulating in the Y direction. The waveform is not to scale here, but is greatly exaggerated. Typically, the amplitudes of the waves formed in the pipe are in the millimeter range or less for pipe lengths of one to two meters. The wave extends along the longitudinal direction L, which here corresponds to the Z direction. Wave-like bulges can also occur in the X direction (not shown), superimposed on the waveform in the Y direction. The bulges do not have to be wave-like.

[0055] The pipe 1 has the actual outer surface 11, which deviates from the straight desired outer surface extending in the longitudinal direction L. A deviation profile can be determined along the longitudinal direction L by calculating the difference between the actual outer surface and the desired outer surface. The straightening machine 10 has a holder 16, on the front sides of which tool tips 5, 6 for pipe clamping and pipe rotation are arranged. The holder 16 can have a preferably conical support surface for supporting the pipe 1. Here, the holder 16 is to be understood as the clear distance between the two tool tips 5, 6. The tool tips 5, 6 can be moved back and forth individually along travel axes A and B, respectively, which are both arranged in the Z direction. The tool tips 5, 6 can also be each aligned in the XY plane in Fig. 1 each one individually movable. In Fig.1A travel axis C for one tool tip 5 and a travel axis D for the other tool tip 6 are shown, both running in the Y direction. The two travel axes in the X direction of the two tool tips 5, 6 are not shown. The two tool tips 5, 6 are arranged exactly opposite each other, so that their axes of rotation extend from one another. The pipe 1 can be clamped between them by moving the tool tips 5, 6 towards each other. The clamped pipe 1 can be rotated by rotating the tool tips 5, 6.

[0056] Along the holder 16 located between the tool tips 5, 6, measuring probes 2 for measuring the straightness of the pipe 1 are arranged at a distance from one another along the longitudinal direction L. The distances from one another can be equidistant. Different distances can also be selected. The measuring probes 2 can also be arranged at different angles in the cross-section perpendicular to the longitudinal direction L around the holder 16 and the pipe 1. The measuring probes 2 can be tactile or optical or have a different design. They enable distance measurements in the range with an accuracy of 0.1 µm or less. The measuring probes 2 for measuring the straightness of the pipe 1 are connected in a data-conducting manner to a controller with a data memory in which, in particular, distance measured values ​​of the individual measuring probes 2 to measuring points on the outer surface 11 of the pipe 2 are stored. The straightness of the pipe 1 is measured in such a way that the pipe 1 is Fig. 1 is clamped, the measuring probes 2 each carry out a first distance measurement, the pipe 1 is rotated a short distance by an angle α, β, the measuring probes 2 carry out a second distance measurement in the rotated angular position, the pipe 1 is rotated by a further angle α, β and the measuring probes 2 carry out a third distance measurement and so on. The distance measurement values ​​are stored and evaluated together with the position of the measuring probe 2 along the longitudinal direction L and the angular position, and the actual outer surface 11 of the pipe 1 is determined. The actual outer surface 11 of the pipe 1 deviates from the straight target outer surface of the pipe 1. In Fig. 1 Pipe 1 is shown exaggeratedly curved.

[0057] For further processing of the tubes 1, deviations from straightness within a specified tolerance of 1 µm or less are typically tolerated. Deviations outside the tolerance range are sorted out and straightened according to the invention. The tube 1 is straightened by the straightening machine 10 according to the invention to return it within the tolerance range.

[0058] The straightening of the pipe 1 is preferably done with the help of two anvils 3, 4, which are Fig. 1are shown schematically and by means of an inventive straightening hammer 8, in which an integrated measuring probe 7 is arranged centrally. 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 embedded. The integrated measuring probe 7 can be moved back and forth along a vertical travel axis J within the straightening hammer 8 relative to the straightening hammer 8 and can disappear into the straightening hammer 8 with a measuring surface 7a aligned with an impact surface 8a of the straightening hammer 8.

[0059] The integrated measuring probe 7 is mounted in the straightening hammer 8 with a return spring 15, which presses the measuring surface 7a out of the striking surface 8a in the load-free state.

[0060] The straightening hammer 8 is according to Fig. 1along a vertical travel axis H towards and away from the pipe 1, it is movable along a horizontal travel axis G along the longitudinal direction L of the pipe 1 and also along a (not shown) horizontal travel axis perpendicular to the longitudinal direction L. The measuring surface 7a of the measuring probe 7 is, as in Fig. 1 shown, also parallel to the travel axis H of the straightening hammer 8, preferably very easily, ie almost resistance-free.

[0061] Fig. 2 shows the arrangement of the straightening hammer 8, the measuring probe 7, the two anvils 3, 4, and the pipe 1 clamped between the tool tips 5, 6 immediately before straightening. The two anvils 3, 4 can be moved back and forth along the longitudinal direction L along travel axes E, F.

[0062] From the deviation profile of the actual from the target outer surface of the pipe 1, a forming position 12 of the straightening hammer 8 on the pipe 1 and support points 13, 14 of the pipe 1 on the anvils 3, 4 are calculated using known Kl algorithms or machine learning algorithms, for example known from Deep Learning with Python and Keras (ISBN 978-3-95845-838-3). This allows the positions of the travel axis G and angles α, β of the two angle tips 5, 6 and the required target deformations of the pipe 1 at the forming position 12 to be calculated in order to straighten the pipe when the pipe 1 is supported between the two anvils 3, 4 spaced apart at a certain distance from each other.

[0063] The problem is that the target deformation at the forming position 12 of the pipe 1 and a forming stroke h of the straightening hammer 8 cannot be clearly assigned to each other.

[0064] The straightening process in the prior art is fundamentally always the same. In order to plastically deform the pipe 1, it is first necessary to apply the forming stroke h to the pipe 1 using the straightening hammer 8 and exceed the elastic range of deformation. Only after the elastic deformation does a plastic deformation s occur. The forming stroke h of the straightening hammer 8 must fundamentally correspond to the elastic deformation plus the plastic deformation s. When the straightening hammer 8 is moved back and the pipe 1 is relieved of pressure, the elastic deformation component essentially springs back, and only the plastic deformation component remains, which here also corresponds to the actual plastic deformation s_actual.

[0065] Although it is generally known how large the plastic deformation s should be at the forming position 12 in order to achieve sufficient straightness of the pipe 1 through straightening, there is no known function between the elastic deformation component and the plastic deformation component of the forming stroke h. The function between the elastic deformation component and the plastic deformation component depends on many conditions, in particular the properties of the material, work hardening or other material fluctuations. However, they are so different that even within a length of a pipe 1 the function between the elastic component and the plastic component is not predictable. It is therefore not known with certainty which forming stroke h must be performed by the straightening hammer 8 in order to achieve a desired target deformation s_soll.Although the potential forming stroke h can be predicted using statistical methods, there is a significant probability that tube 1 will be plastically deformed too much or too little. If overforming occurs, tube 1 would have to be remeasured, lifted from anvils 3 and 4, rotated, set down again, and straightened again. This is time-consuming.

[0066] In Fig. 6 The idea of ​​the procedure is shown schematically, which is used in the Figures 2 , 3 , 4 , 5 is carried out. Fig. 6first shows a predefined characteristic map 60, which can be obtained using statistical methods in conjunction with artificial intelligence, machine learning, etc., for example according to deep learning with Python and Keras (ISBN 978-3-95845-838-3). There, 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 distances between the two anvils 3, 4 and the position of the straightening hammer 8 are also included in the characteristic map 60. The characteristic map 60 can be read such that when a first forming stroke h_1 is carried out, an actual plastic deformation s_actual is within a deformation range b along the X-axis within the characteristic map 60. The actual plastic deformation s_ist is within the deformation range b with a probability of 95%, 99%, 99.9%.The width of characteristic map 60, i.e., the length of the deformation range b in the X-direction, depends primarily on the material properties. The width depends in particular on residual stresses in the material, strain hardening, or other material fluctuations. However, while the global shape of characteristic map 60 also depends on the distance between anvils 3 and 4, the diameter of tube 1, the wall thickness of tube 1, etc., these are all parameters that allow for precise prediction of bending behavior and do not significantly influence the width of characteristic map 60 itself. They only influence the global shape, i.e., the gradient of characteristic map 60, etc.

[0067] Furthermore, it is known that the actual deformation s_ist of a rod-shaped material, in particular of the tube 1, which is subjected to a different first forming stroke h at a forming position 12, follows a characteristic curve 61 which is within the Fig. 6shown characteristic map 60. The characteristic curve 61 is inserted into the characteristic map 60. It has been found that the characteristic curve 61 within the characteristic map 60 can also be precisely specified in reality by two points.

[0068] The process according to the invention proceeds as described below.

[0069] The pipe 1 is formed in a known manner according to Fig. 2 on the anvils 3, 4 at a specific angle α, β. The forming position 12 of the straightening hammer 8 and the support points 13, 14 on the anvils 3, 4 are known. The straightening hammer 8 is positioned in a first process step according to Fig. 2 arranged above the forming position 12 by means of the travel axis G. It is known how large the desired plastic deformation s_soll must be at the forming position 12 in order to be able to provide a tube 1 that is as straight as possible after the straightening process.

[0070] In a second process step, according to Fig. 3the straightening hammer 8 is moved along the travel axis H in the direction of the forming position 12 of the pipe 1 until the measuring surface 7a of the measuring probe 7 touches the outer surface of the pipe 1. However, the measuring probe 7 does not exert any pressure on the forming position 12, which would already bend the pipe. The straightening hammer 8 is in the zero position. The zero position is determined, and its coordinates are recorded. A first measurement is now carried out in the zero position by the measuring probe 7, and the first measured values ​​of the measuring probe 7 are saved. For example, the measured data such as how far the measuring surface 7a of the measuring probe is from the striking surface 8a in the Y direction or a similar measurement are recorded. The first measured values ​​are measured values ​​that determine 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 only important that the position of the forming position 12 relative to the straightening hammer 8 is maintained.

[0071] In a third step, according to Fig. 4 the first forming stroke h_1 is applied to the forming position 12.

[0072] 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, Fig. 6the intersection point of the target deformation s_soll with the lower, minimum limit of the characteristic map 60 is determined. The intersection point specifies the first forming stroke h_1. The selected first forming stroke h_1 statistically generates a target deformation s_soll for the material within the deformation range b. The target deformation s_soll is only achieved by the first forming stroke h_1 in the best case scenario. If this is not the case, an actual deformation s_ist is produced that is below the target deformation s_soll within the deformation range b. The tube 1 is therefore deformed less than it actually needs to be.

[0073] The deformation process takes place according to Fig. 4 by the straightening hammer 8, which is fixedly mounted on an NC-controlled axis H. The straightening hammer 8 is moved by means of the NC-controlled axis H according to Fig. 4 by the first forming stroke h_1 against the Y-direction and bends the tube 1 according to Fig. 4to some extent. The bending contains an elastic and a plastic component.

[0074] In Fig. 5 The straightening hammer 8 has been moved back, and the elastic deformation has disappeared. The plastic deformation s remains and straightens the pipe 1.

[0075] The information acquisition according to the invention is carried out by the measuring probe 7. Then the straightening hammer 8 is moved in a fourth process step according to Fig. 5 back, the pipe 1 is relieved, the straightening hammer 8 is moved to the zero position according to Fig. 3moved back, and a second measurement is performed using the measuring probe 7, and second measured values ​​are determined. The second measured values ​​are compared with the first measured values ​​of the measuring probe 7, and the actual deformation s_actual after the first forming stroke h_1 is determined from the difference between the measured values, for example the difference between the distances of the forming position 12 and the striking surface 8a of the straightening hammer 8.

[0076] The inventive idea is to significantly narrow down the characteristic map 60 from the information about the first actual deformation s_actual in order to be able to carry out a second forming stroke h_2 much more precisely and to get very close to the target deformation s_soll.

[0077] The actual plastic deformation s_actual after the first forming stroke h_1 does not usually correspond to the desired plastic deformation s_desired, but is less than the desired deformation s_desired. However, the measurements of the measuring probe 7 allow a concrete value to be specified for the actual deformation s_actual that was generated by the first forming stroke H_1, so that according to Fig. 6 the first forming stroke h_1 can be assigned an actual deformation s_ist, and thus the forming position 12 with its specific material properties can be assigned the characteristic curve 61 within the characteristic field 60 in Fig. 6 The characteristic curve 61 represents the plastic deformation behavior at different strokes h for the forming position 12.

[0078] In a further procedural loop, according to the Figures 3 , 4 , 5The tube 1 is straightened at the forming position 12 by means of the second forming stroke h_2. The size of the second forming stroke h-2 is determined from the characteristic curve 61 in Fig. 6 and its intersection point with the desired deformation s_soll.

[0079] If necessary, the process loop can be repeated a third or fourth time. Practical implementation of the process has shown that multiple process loops are necessary. Furthermore, it has also been demonstrated that specified straightness tolerances can be met with great reliability using this process, which iteratively approaches the target deformation s_soll. List of reference symbols

[0080] 1Tube / rod material 2Measuring probe 3Anvil 4Anvil 5Tool tip 6Tool tip 7 7aMeasuring surface 8Straightening hammer 8aStrike surface 10Straightening machine 11Actual outer surface 12Forming position 13Support point 14Support point 15Return spring 16Recording 60Characteristic map 61Characteristic curve bDeformation range hForming stroke h_1first forming stroke h_2second forming stroke splastic deformation s_actualplastic actual deformation s_desireddesired deformation ATravel axis BTravel axis CTravel axis DTravel axis ETravel axis FTravel axis GVertical travel axis HHorizontal travel axis JTravel axis Longitudinal direction αangle βangle

Claims

1. Method for straightening non-straight bar-shaped material (1), in that a plastic target deformation (s_soll) is determined at a forming position (12) of the bar-shaped material (1), a straightening hammer (8) with integrated measuring probe (7) is moved to the forming position (12), a characteristic diagram (60) is provided which indicates a plastic deformation span (b) for the material for each forming stroke (h), a first forming stroke (h_1) of the straightening hammer (8) is carried out, an plastic actual deformation (s_ist) caused by the first forming stroke (h_1) is determined by means of the integrated measuring probe (7), the characteristic curve (61) of the bar-shaped material (1) within the characteristic diagram (60) is determined from the actual deformation (s_ist) after the first forming stroke (h_1) and the second forming stroke (h_2) is determined from the characteristic curve (61) in that the second forming stroke (h_2) corresponds to a forming stroke (h) to the plastic target deformation (s_soll) along the characteristic curve (61).

2. Method according to claim 1, characterised in that the target deformation (s_soll) within the upper 10% of the deformation span (b) is preferably selected as the maximum value of the deformation span (b) of the first forming stroke (h_1).

3. Method according to claims 1 or 2, characterised in that an elastic deformation of the material and the plastic actual deformation (s_ist) within the deformation span (b) is carried out by the first forming stroke (h_1).

4. Method according to any of the preceding claims, characterised in that the first deformation stroke (h_1) is selected such that the deformation span (b) associated therewith has a maximum value corresponding to the target deformation (s_soll), and the actual deformation (s_ist) generated 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. Method according to any of the preceding claims, characterised in that the target deformation (s_soll) is determined at the forming position (12) of the bar-shaped material (1), the bar-shaped material (1) is clamped, a zero position of the straightening hammer (8) is determined, a first measured value of the integrated measuring probe (7) is determined in the zero position of the straightening hammer (8), the first forming stroke (h_1) of the straightening hammer (8) is executed, the straightening hammer (8) is moved back to the zero position, a second measured value of the measuring probe (7) is determined in the zero position of the straightening hammer (8) and the plastic actual deformation (s_ist) of the bar-shaped material (1) by the first forming stroke (h_1) is determined from the first and second measured values, the plastic actual deformation (s_ist) is compared with the plastic target deformation (s_soll).

6. Method according to any of the preceding claims, characterised in that a tolerance range is specified and if, after the first forming stroke (h_1) has been carried out, a difference between the actual deformation (s_ist) and the target deformation (s_soll) lies outside the tolerance range, the second forming stroke (h_2) is carried out at the forming position (12).

7. Method according to any of the preceding claims, characterised in that an actual outer surface of the bar-shaped material (1) is measured and a deviation profile of the actual outer surface from a straight-line target outer surface is determined, the forming position (12) is determined from the deviation profile.

8. Method according to claim 7, characterised in that the forming position (12) is determined from the deviation profile as an angle (α, β) about a longitudinal direction (L) of the bar-shaped material (1) and as a position along a travel axis (G) of the straightening hammer (8) along the longitudinal direction (L).

9. Straightening machine for non-straight, bar-shaped material (1) for carrying out a plastic target deformation (s_soll) at a forming position (12) of the bar-shaped material (1) with a control for a traversing device with a straightening hammer (8) with integrated measuring probe (7), with a memory for a characteristic diagram (60) which indicates an plastic actual deformation span (b) for the material for each forming stroke (h), whereby through the control a first forming stroke (h_1) is definable from the target deformation (s_soll), an plastic actual deformation (s_ist) caused by the first forming stroke (h_1) is measurable through the integrated measuring probe (7) and its measured values is feedable to the control via a data-conducting connection, a characteristic curve (61) within the characteristic diagram (60) can be determined from the actual deformation (s_ist) in the control system and a second forming stroke (h_2) can be determined by the control from the target deformation (s_soll) and the characteristic curve (61).

10. Straightening machine according to claim 9, characterised by at least two anvils (3, 4) spaced from each other in a longitudinal direction (L) for supporting the bar-shaped material (1).

11. Straightening machine according to claim 9 or 10, characterised in that the integrated measuring probe (7) with a measuring head (7a) is guided centrally through the straightening hammer (8) and the measuring head (7a) enables a distance measurement beyond an impact surface (8a) of the straightening hammer (8).

12. Straightening machine according to claim 9, 10 or 11, characterised in that the integrated measuring probe (7) is a tactile measuring probe, the measuring head (7a) of which projects centrally from a bore of the straightening hammer (8) and can be returned completely on the inside behind the striking surface (8a) of the straightening hammer (8).

13. A straightening machine according to claim 12, characterised in that a measuring system for measuring an outer surface of the bar-shaped material (1) is arranged along a receptacle (16) for the bar-shaped material (1) and that the measuring system comprises oppositely arranged, rotatable holders (5, 6) for clamping the bar-shaped material (1) and measuring probes (2) arranged between the holders (5, 6), which are arranged next to the clamped bar-shaped material (1).