Method for operating a roller straightening machine for metal products

Abstract

The invention relates to a method for operating a roller straightening machine (1) for metal products (2), said straightening machine (1) having a number of straightening rollers (3, 4, 5, 6, 7) which contact the metal product (2) to be straightened at two opposite sides of the product (2) during the straightening process and exert a bending moment and / or a shear force on the product (2) by advancing (x) the rollers towards the product (2), wherein each straightening roller (3, 4, 5, 6, 7) has an electromotive drive (8) by means of which the straightening roller (3, 4, 5, 6, 7) can be driven. The aim of the invention is to ensure that torques are distributed across the individual straightening rollers as advantageously as possible. This is achieved in that the method has the steps of: a) prior to starting the straightening process: ascertaining a target distribution of the total drive torque of all of the straightening rollers (3, 4, 5, 6, 7) across the individual straightening rollers (3, 4, 5, 6, 7); b) during the straightening process: b1) ascertaining the force exerted by the straightening rollers (3, 4, 5, 6, 7) on the product (2) in a direction normal to the product (2); b2) determining all of the straightening rollers (3, 4, 5, 6, 7) actively involved in the straightening process; b3) ascertaining a redistribution of the total drive torque across the straightening rollers (3, 4, 5, 6, 7) actively involved in the straightening process; and b4) driving the straightening rollers (3, 4, 5, 6, 7) actively involved in the straightening process using the redistributed drive torque according to step b3).

Description

[0001] Method for operating a roller straightening machine for metallic goods

[0002] The invention relates to a method for operating a roller straightening machine for metallic material, wherein the straightening machine has a number of straightening rollers which contact the metallic material to be straightened on two opposite sides of the material during the straightening process and exert a bending moment and / or a shearing force on the material by feeding it towards the material, wherein each straightening roller has an electric motor drive with which the straightening roller can be driven.

[0003] To ensure that metal products have the flattest possible shape after processing, straightening machines of this type are well known in the art. The product enters the straightener on one side and is straightened by the action of the straightening rollers.

[0004] The challenge is determining exactly which torque is applied to the individual straightening rollers to ensure the most effective straightening process. One option is to measure the torque applied to one straightening roller and designate that roller as the "master." The other straightening rollers are then subjected to the torque specified by the master straightening roller as "slaves" ("master-slave operation").

[0005] However, this approach has disadvantages. In particular, inadequate torque distribution among the individual straightening rollers is a major concern. Instabilities in the drive control system are also possible. The available capabilities of the drive motor converters are sometimes underutilized, which is a disadvantage. Another disadvantage is that an uneven or uncontrolled load distribution is observed among the motors driving the straightening rollers, which results in unfavorable oversizing of the drives. Furthermore, uncontrolled load distribution among the individual straightening rollers can cause damage to the surface of the metal material being straightened.

[0006] The invention is based on the object of designing a method of the type mentioned above in such a way that the aforementioned disadvantages are avoided. Accordingly, the most favorable distribution of torque among the individual straightening rollers is to be ensured. The drive power required to drive the straightening rollers is to be kept as low as possible. Furthermore, the machine equipment is to be protected against overload. Overall, this should result in increased energy efficiency of the machine and high product quality.

[0007] The solution to this problem by the invention is characterized in that the method comprises the steps: a) before the start of the straightening process: determination of a target distribution of the total drive torque of all straightening rollers to the individual straightening rollers; b) during the straightening process: b1) determination of the force in the direction normal to the material which at least a number of the straightening rollers exert on the material; b2) determination of all straightening rollers actively involved in the straightening process, which results from the fact that all straightening rollers actively involved in the straightening process exert a force in the direction normal to the material of greater than zero on the material; b3) determination of a redistribution of the total drive torque to the straightening rollers actively involved in the straightening process; for this purpose, a distribution pattern can be provided, as described in detail below for two examples;b4) Driving the straightening rollers actively involved in the straightening process with the newly distributed drive torque according to step b3).;

[0008] In connection with step b2), it should be noted that it is of course also possible to adjust the straightening rollers axially, which has a corresponding influence on the torque.

[0009] The above steps b1) to b4) are preferably repeated periodically within the framework of a control by a control or regulating device.

[0010] The target distribution of the total drive torque of all straightening rollers to the individual straightening rollers according to step a) above can be done in such a way that all straightening rollers are driven with the same torque. However, this is by no means mandatory, which is especially true if different drive components are used in the straightening machine (e.g., smaller drives in the outfeed).

[0011] Alternatively, it is also possible that the target distribution of the total drive torque of all straightening rolls to the individual straightening rolls according to step a) above is carried out using an analytical and / or numerical process model of the roll straightening process.

[0012] The determination of the force in the direction normal to the material according to step b1) above can be carried out for all straightening rollers located above the material (alternatively: below the material). The determination of the force in the direction normal to the material according to step b2) above can be carried out for all straightening rollers.

[0013] The torque of the straightening rollers is usually specified by specifying the motor current.

[0014] The force in the direction normal to the material according to step b1) above can be determined by measuring the pressure of a hydraulic feed drive for the corresponding straightening roller. However, other methods of force measurement are also possible (such as load cells or strain gauges). Instead of hydraulic feed drives, other feed drives, particularly electric ones, can also be used.

[0015] The proposed concept is therefore based on the idea of ​​considering all straightening rollers involved in the process with regard to their drive torques. There is therefore no "master" that then specifies drive torques for the other straightening rollers as "slaves." The process can start when frictional contact is established in the first straightening triangle (one straightening roller on one side of the material and two straightening rollers on the other side of the material) and end when the material to be straightened leaves the last straightening triangle.

[0016] According to the invention, the entire drive element of all straightening rollers actively involved in the straightening process is distributed to the individual active drives according to a predetermined distribution pattern.

[0017] The process control is independent of process specifications such as roll diameter or roll feed. Only the respective actual drive torques of the drives are required. A pure P-controller is preferably not used. Higher frequency components of the control intervention can be filtered out. This ensures stable control throughout the entire straightening process, including the threading of the material into and out of the straightener.

[0018] With a predefined roll feed, the required drive torques can be predicted relatively precisely over the straightening time using numerical methods, whereby the threading of the material into and out of the straightener can also be taken into account. Based on this calculation, the total drive torque of all straightening rolls can be distributed specifically among the individual rolls; this makes it possible to significantly shorten experimental calibration of the straightener. For this purpose, a catalog of setting parameters can be created and taken into account in advance if necessary. However, the drive torques that arise in practice and result from the straightening process cannot usually be precisely predicted. The selection of the distribution factors can therefore also be made with the aid of expert knowledge.

[0019] The proposed approach makes it possible to minimize the installed drive power of the straightening roller drives. The straightening machine is also effectively protected against overload. High product quality of the straightened metal product is achieved. The energy required to operate the straightening machine is used efficiently.

[0020] Another advantage is that product properties can be better predicted and influenced, particularly with regard to the residual stresses in the metallic material.

[0021] Another advantage is that the straightening machine can be commissioned in a shorter time and the effort required for this is minimized. This also results in corresponding cost savings. Finally, it should be mentioned that wear on the straightening rollers can be reduced, thus correspondingly lowering operating costs. Another advantage is that the load on the other drive components (gearboxes, drive shafts, couplings, etc.) is also reduced and evened out.

[0022] The distribution factors therefore determine the percentage share of all drive torques on the respective drive train, i.e., the share of each motor in the total drive torque required for the straightening process. The sum of all distribution factors must be 1.0.

[0023] The sum of all torques results from the drives currently involved in the process. This varies particularly during the entry and exit of the metal to be straightened.

[0024] When selecting the distribution factors, the ultimate goal is to achieve load balancing control that ensures even utilization of all drives while taking their individual nominal torque into account. Due to the model underlying the straightening process, the greatest forming work is always performed in the front straightening triangles, which also results in a high demand for drive power here. In contrast, the straightening rollers located at the machine's outlet require significantly less torque from the straightening process to pull the metal to be straightened through the machine. In practice, this is often reflected in the use of smaller, less powerful drives on the rear straightening axes. At the same time, however, there is often still a power reserve in the outlet-side motors, which can be used to relieve the load on the front drives.Furthermore, it should be noted that the transferable power also depends on the contact pressure between the material and the straightening roller, and therefore cannot be set to an arbitrary level by the control system. This is to avoid slippage of the rollers relative to the material and / or local deformation of the metal being straightened. This is especially important when determining the factors for the first and last straightening rollers.

[0025] The drawing illustrates an embodiment of the invention. The sole figure shows a schematic side view of a roller straightening machine in which a metallic product is being straightened.

[0026] The figure schematically shows a straightening machine 1 for metallic material 2. The straightening machine 2 has a number of straightening rollers 3, 4, 5, 6, 7. These rollers contact the metallic material 2 to be straightened on two opposite sides of the material 2 during the straightening process. By advancing the straightening rollers toward the material 2 (see infeed x), a bending moment or shear force is exerted on the material 2, thereby initiating the straightening process.

[0027] Each straightening roller 3, 4, 5, 6, 7 has an electric motor drive 8, which can be used to drive the straightening roller 3, 4, 5, 6, 7. With the drive 8 (which is shown in the figure only for one of the straightening rollers, but which is present for each straightening roller), a drive torque M can be applied to the straightening rollers.

[0028] Each drive 8 is connected to a control device 9. The control device 9 receives the determined forces that each of the straightening rollers, or at least a number of the straightening rollers, exerts normally on the surface of the material 2. For this purpose, the pressure of a hydraulic feed drive 10 can be detected and transmitted to the control device 9, which is then applied to the feed drive 10 to exert a force on the material 2.

[0029] The proposed procedure is carried out as follows:

[0030] First, before the start of the straightening process, a target distribution of the total drive torque of all straightening rollers is determined among the individual straightening rollers 3, 4, 5, 6, 7. According to one possible embodiment of the method, it can be provided that all straightening rollers 3, 4, 5, 6, 7 are subjected to the same target torque. In the exemplary embodiment with five straightening rollers, this would mean that each straightening roller should be subjected to 20% of the total drive torque of all straightening rollers (in practice, however, the straightening rollers are usually subjected to uneven loading in order to be able to specifically take into account the inlet and outlet from the straightening machine 1).

[0031] When the straightening process starts or is carried out, the following steps are carried out:

[0032] The force in the direction normal to the material 2 is determined, with which the straightening rollers 3, 4, 5, 6, 7 are acted upon and with which they contact the material 2. For this purpose, it is not absolutely necessary to carry out the force measurement for each straightening roller. In particular, it may be sufficient to only carry out the force measurement for the rollers above the material 2, i.e. in the exemplary embodiment for the straightening rollers 4 and 6. If, for example, a force is determined for the straightening roller 4 with which it presses onto the material 2, it can be concluded for the straightening roller 3 that this also exerts a (counter) force when the material 2 passes the straightening machine 1 from left to right (in the direction of the arrow) in the figure.

[0033] Based on the determined forces, all straightening rollers actively involved in the straightening process can then be identified. This results from the fact that such straightening rollers exert a force in the direction normal to the product 2 that is greater than zero on the product 2 (in this regard, it should be noted that a certain tolerance for the value "zero" can of course also be specified, i.e. a very low value for the force, which is nevertheless reliable for ensuring that no relevant straightening torque is exerted on the product). The next step involves determining a redistribution of the entire drive torque to the straightening rollers actively involved in the straightening process. Accordingly, a drive torque is only specified for those straightening rollers that are active and in engagement. The inactive straightening rollers are therefore not intended to be subjected to a drive torque.

[0034] Finally, the straightening rollers actively involved in the straightening process are driven with the newly distributed drive torque determined in this way.

[0035] This procedure will be illustrated once again by examples, with reference to the figure.

[0036] Example 1 :

[0037] First, assume that the target distribution of the total drive torque among the straightening rollers is to be evenly distributed. Accordingly, each of the five straightening rollers 3, 4, 5, 6, and 7 would be subjected to 20% of the total drive torque.

[0038] During the straightening process, material 2 – coming from the left and conveyed to the right in the direction of the arrow – has reached the straightening rollers (the arrow indicates the conveying direction of material 2). Let us first assume that material 2 has only entered the straightening machine 1 far enough to make contact only with straightening rollers 3 and 4; accordingly, there is no contact yet with straightening rollers 5, 6, and 7.

[0039] If the force is now determined in the direction normal to material 2, a value other than zero results for straightening rollers 3 and 4; for straightening rollers 5, 6, and 7, the value is zero, since there is no contact between material 2 and these rollers yet. Accordingly, determining all straightening rollers actively involved in the straightening process results in (only) straightening rollers 3 and 4.

[0040] The determination of a redistribution of the total drive torque to the straightening rollers 3 and 4 actively involved in the straightening process is now carried out as follows:

[0041] Distribution factor for straightening roll 3: 20% / (20% + 20%) = 0.5 Distribution factor for straightening roll 4: 20% / (20% + 20%) = 0.5

[0042] The distribution factor or distribution pattern is therefore determined from the share of the total torque originally intended for the relevant straightening roller (20%) divided by the sum of the intended shares (20% each) of those straightening rollers that are active (in this case, these are two straightening rollers).

[0043] Accordingly, the total drive torque is distributed equally (distribution factor 0.5) between the two straightening rollers 3 and 4.

[0044] If the product 2 has entered the straightening machine 1 and the product 2 now has contact with the straightening rollers 3, 4 and 5, the distribution factors are as follows, since now three straightening rollers, namely the straightening rollers 3, 4 and 5, are active:

[0045] Distribution factor for straightening roll 3: 20% / (20% + 20% + 20%) = 0.333 Distribution factor for straightening roll 4: 20% / (20% + 20% + 20%) = 0.333 Distribution factor for straightening roll 5: 20% / (20% + 20% + 20%) = 0.333

[0046] Accordingly, the total drive torque is now distributed equally among the three involved straightening rollers 3, 4, and 5. Similarly, if the product 2 has entered the straightening machine 1 further to the right and is now in contact with the straightening rollers 3, 4, 5, and 6, the following distribution factors apply:

[0047] Distribution factor for straightening roll 3: 20% / (20% + 20% + 20% + 20%) = 0.25

[0048] Distribution factor for straightening roll 4: 20% / (20% + 20% + 20% + 20%) = 0.25

[0049] Distribution factor for straightening roll 5: 20% / (20% + 20% + 20% + 20%) = 0.25

[0050] Distribution factor for straightening roll 6: 20% / (20% + 20% + 20% + 20%) = 0.25

[0051] If the product 2 has now completely entered the straightening machine 1 and has contact with all five straightening rollers 3, 4, 5, 6 and 7, the distribution factors are finally as follows:

[0052] Distribution factor for straightening roll 3: 20% / (20% + 20% + 20% + 20% + 20%) = 0.2

[0053] Distribution factor for straightening roll 4: 20% / (20% + 20% + 20% + 20% + 20%) = 0.2

[0054] Distribution factor for straightening roll 5: 20% / (20% + 20% + 20% + 20% + 20%) = 0.2

[0055] Distribution factor for straightening roll 6: 20% / (20% + 20% + 20% + 20% + 20%) = 0.2

[0056] Distribution factor for straightening roll 7: 20% / (20% + 20% + 20% + 20% + 20%) = 0.2

[0057] The total drive torque is distributed accordingly to the active straightening rollers using the calculated distribution factors, and the straightening process is carried out.

[0058] Example 2:

[0059] If the distribution to the individual straightening rollers is not even, but uneven (e.g. for the first and last straightening rollers 3 and 7 not 20%, but only 15% each, while the straightening rollers 4 to 6 are to be charged with 23.3% each - which in turn results in a total of 100%), these values ​​take the appropriate place in the calculation of the distribution factor.

[0060] The following values ​​would then result for the distribution factors:

[0061] Straightening rollers 3 and 4 active:

[0062] Distribution factor for straightening roll 3: 15% / (15% + 23.3%) = 0.392

[0063] Distribution factor for straightening roll 4: 23.4% / (15% + 23.3%) = 0.608

[0064] Straightening rollers 3, 4 and 5 active:

[0065] Distribution factor for straightening roll 3: 15% / (15% + 23.3% + 23.3%) = 0.244

[0066] Distribution factor for straightening roll 4: 23.3% / (15% + 23.3% + 23.3%) = 0.378

[0067] Distribution factor for straightening roll 5: 23.3% / (15% + 23.3% + 23.3%) = 0.378

[0068] Straightening rollers 3, 4, 5 and 6 active:

[0069] Distribution factor for straightening roll 3: 15% / (15%+23.3%+23.3%+23.3%) = 0.177

[0070] Distribution factor for straightening roll 4: 23.3% / (15%+23.3%+23.3%+23.3%) = 0.274

[0071] Distribution factor for straightening roll 5: 23.3% / (15%+23.3%+23.3%+23.3%) = 0.274

[0072] Distribution factor for straightening roll 6: 23.3% / (15%+23.3%+23.3%+23.3%) = 0.274

[0073] Straightening rollers 3, 4, 5, 6 and 7 active:

[0074] Distribution factor for straightening roll 3: 15% / (15%+23.3%+23.3%+23.3%+15%)=0.15

[0075] Distribution factor for straightening roll 4: 23.3% / (15%+23.3%+23.3%+23.3%+15%)=0.233

[0076] Distribution factor for straightening roll 5: 23.3% / (15%+23.3%+23.3%+23.3%+15%)=0.233 Distribution factor for straightening roll 6: 23.3% / (15%+23.3%+23.3%+23.3%+15%)=0.233 Distribution factor for straightening roll 7: 23.3% / (15%+23.3%+23.3%+23.3%+15%)=0.15

[0077] This demonstrates that the total drive torque of all straightening rollers is always optimally distributed among the active straightening rollers. Therefore, "master-slave operation" is not provided. This results in a more uniform distribution of the drive torque across the individual straightening rollers, thus resulting in the aforementioned advantages.

[0078] Example 3:

[0079] With a view to taking into account different distribution factors for the inlet and outlet from the machine (as explained above), the following example is given:

[0080] To clarify the determination of the distribution factors, a simplified example of a straightening machine with 8 rollers and individual drive is considered here.

[0081] The machine should be equipped with identical drive components so that the rated power of each motor is identical.

[0082] A theoretically ideal distribution would result in a proportion of 12.5% ​​for each strand, which can be varied within a suitable range due to the physical laws described above.

[0083] For example, the regulation could allocate a share of 8% to 12% to the first and last roles, and distribute the remaining 76% to 84% to the other roles in a range of 10% to 15%.

[0084] List of reference symbols:

[0085] 1 roller straightening machine

[0086] 2 metallic goods (metal strip)

[0087] 3 straightening roller

[0088] 4 straightening rollers

[0089] 5 straightening roller

[0090] 6 straightening roller

[0091] 7 straightening roller

[0092] 8 electric motor drive

[0093] 9 Control or regulating device

[0094] 10 hydraulic feed drive

[0095] X Delivery

[0096] M drive torque

Claims

Patent claims:

1. A method for operating a roller straightening machine (1) for metallic material (2), wherein the straightening machine (1) has a number of straightening rollers (3, 4, 5, 6, 7) which contact the metallic material (2) to be straightened on two opposite sides of the material (2) during the straightening process and exert a bending moment and / or a shearing force on the material (2) by feeding (x) towards the material (2), wherein each straightening roller (3, 4, 5, 6, 7) has an electric motor drive (8) with which the straightening roller (3, 4, 5, 6, 7) can be driven, characterized in that the method comprises the steps of: a) before the start of the straightening process: determining a target distribution of the total drive torque of all straightening rollers (3, 4, 5, 6, 7) to the individual straightening rollers (3, 4, 5, 6, 7); b) during the straightening process: b1 ) determining the force in the direction normal to the material (2) which at least a number of the straightening rollers (3, 4, 5, 6, 7) exert on the material (2);b2) Determination of all straightening rollers (3, 4, 5, 6, 7) actively involved in the straightening process, which results from the fact that all straightening rollers (3, 4, 5, 6, 7) actively involved in the straightening process exert a force in the direction normal to the material (2) of greater than zero on the material (2); b3) Determination of a redistribution of the total drive torque to the straightening rollers (3, 4, 5, 6, 7) actively involved in the straightening process; b4) Driving the straightening rollers (3, 4, 5, 6, 7) actively involved in the straightening process with the newly distributed drive torque according to step b3).

2. Method according to claim 1, characterized in that the steps b1) to b4) are permanently repeated periodically within the framework of a control by a control or regulating device (9).

3. Method according to claim 1 or 2, characterized in that the target distribution of the total drive torque of all straightening rollers (3, 4, 5, 6, 7) to the individual straightening rollers (3, 4, 5, 6, 7) according to step a) of claim 1 is carried out in such a way that all straightening rollers (3, 4, 5, 6, 7) can be driven with the same torque.

4. Method according to claim 1 or 2, characterized in that the target distribution of the total drive torque of all straightening rollers (3, 4, 5, 6, 7) to the individual straightening rollers (3, 4, 5, 6, 7) according to step a) of claim 1 is carried out using an analytical and / or numerical process model of the roller straightening process.

5. Method according to one of claims 1 to 4, characterized in that the determination of the force in the direction normal to the material (2) according to step b1) of claim 1 is carried out for all straightening rollers (4, 6) which are located above the material (2).

6. Method according to one of claims 1 to 5, characterized in that the determination of the force in the direction normal to the material (2) according to step b2) of claim 1 is carried out for all straightening rollers (3, 4, 5, 6, 7).

7. Method according to one of claims 1 to 6, characterized in that the torque of the straightening rollers (3, 4, 5, 6, 7) is specified by specifying the motor current.

8. Method according to one of claims 1 to 7, characterized in that the determination of the force in the direction normal to the material (2) according to step b1) of claim 1 is carried out by measuring the pressure of a hydraulic feed drive (10) for the straightening roller (3, 4, 5, 6, 7).

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