A servo-driven sheet leveling device and a leveling control method

Abstract

The present invention discloses a leveling control method for a servo-driven sheet leveling device. The leveling device mainly consists of leveling rollers, supporting rollers, an upper crossbeam, and inclination adjustment screws for the leveling rollers. According to the thickness specification of the sheet to be leveled, the lifting height position of the upper crossbeam is adjusted through the servo motor and screw structure of the upper crossbeam, thereby determining the distance between the leveling rollers. Then, the inclination of the leveling rollers is adjusted through the screws, enabling the sheet to enter and exit the leveling rollers to form a gradual deformation process. The leveling rollers are powered by a variable-frequency motor, and the leveling rollers are actively rotated through gear transmission to generate pressure for leveling. The function of the supporting rollers connected to the leveling rollers is to support the leveling rollers and prevent them from deforming. During the entire leveling process of the leveling rollers, the servo motor controlling the position of the upper crossbeam can collect the deformation resistance of the leveling rollers. Combining with the leveling result, through several calculations and analyses, the control computer can give the optimal leveling parameter scheme through learning.

Description

Technical Field

[0001] The present invention belongs to the field of material forming and leveling technology, and particularly relates to a servo-driven sheet leveling device. Background Art

[0002] During the process of milling stainless steel sheet parts in a machining workshop, due to the incomplete elimination of the residual stress generated during the rolling stage of the sheet itself, the sheet warps and deforms after milling holes or milling edges, and the flatness seriously exceeds the standard, affecting the quality of the product. Especially for sheets with large elasticity and high tensile strength, such as warping deformation of superalloy sheets and titanium alloy sheets, traditional straightening methods cannot be achieved, and special equipment is required to level the sheet or perform leveling operations after sheet processing to ensure the quality requirements of the workpiece. Through market research, most of the existing equipment is generally applicable to the correction of sheets with low efficiency requirements in small batch production, and is not suitable for leveling equipment with high precision requirements that can be compatible with both thin and thick sheets. To save costs and improve product quality, it is necessary to independently research, develop and produce process equipment suitable for current production needs.

[0003] For sheets with different thickness ranges, there are corresponding fixed models, and the processing of a single model of equipment cannot be compatible with a relatively large thickness range. According to actual needs, sheet parts between 0.5 - 12 mm need to be leveled. The existing equipment requires two models of equipment corresponding to 0.5 - 3.5 mm and 3.5 - 20 mm, and the purchase cost is extremely high. However, there is still a gap in precision control technology, and only by increasing the number of pairs of leveling rollers can the technical deficiencies be filled. In order to pursue high efficiency, the motor power is blindly increased, the equipment volume is relatively bulky, and the cost is naturally relatively high. Currently, the processing range of the existing leveling equipment is 4.0 - 10 mm, and the equipment for 0.5 - 4 mm is used for uncoiling the whole sheet, and the width is relatively large. Therefore, it is imperative to develop equipment with moderate production efficiency, low cost, reliable durability, and precision that can meet general requirements and has a high cost performance. Through checking and calculating, 11 pairs (22 pieces) of leveling rollers and a roll diameter in the range of 50 - 60 mm can meet the leveling processing of sheets with different materials and thicknesses within 1300 mm in width between 0.5 - 12 mm, which is suitable for single-piece and small-batch production modes. The drive adopts the form of a variable-frequency motor with multi-axis input and multi-axis output to ensure the requirements of sheet biting and bending torque, and the leveling movement is stable. For the Z-axis movement control, a servo motor is combined with a high-precision ball screw guide rail, and then a full-closed-loop digital motion control is equipped, which can accurately control the opening and closing distance and the departure angle, and is also convenient to realize automated functions such as parameterization and one-key operation. The flatness can be controlled within 0.2 mm per square meter. Summary of the Invention

[0004] Object of the Invention: Aiming at the problems that the existing leveling machines have complex structures and high costs, and the existing simple structures cannot meet the control accuracy requirements, the present invention provides a servo-driven sheet leveling device. The second object of the present invention is to provide a servo-driven sheet leveling control method to improve the flatness of the sheet by controlling the slow release of the sheet stress.

[0005] Technical Solution: A servo-driven sheet leveling device includes a frame. An upper platform and a lower platform are provided in the middle of the frame. Both the upper platform and the lower platform are provided with supporting rollers. A leveling roller is arranged between the two groups of supporting rollers, and the leveling roller is driven by a variable-frequency motor.

[0006] The upper platform is fixed on the upper crossbeam by an inclination adjustment screw. The inclination adjustment screw is used to adjust the left and right inclination angles of the upper platform. The upper crossbeam is connected to a servo motor located at the top of the frame through a ball nut and a ball screw. The servo motor controls the descending height of the upper crossbeam, thereby controlling the distance between the two groups of supporting rollers. And both sides of the upper crossbeam are matched with ball guide rails and ball sliders to move up and down on the side walls of the frame.

[0007] The leveling roller is driven by a variable-frequency motor. The variable-frequency motor is connected to the leveling roller through a transmission shaft. A plurality of leveling rollers are provided, forming two upper and lower leveling lines, and the middle is used for leveling the steel plate.

[0008] Further, the leveling rollers on the two upper and lower leveling lines are controlled by two independent variable-frequency motors. The variable-frequency motor drives the first leveling roller connected thereto through a transmission shaft, and the leveling rollers on the same leveling line are meshed and linked by gears.

[0009] Furthermore, the servo motor is connected with an electromagnetic brake to control the lifting height of the upper crossbeam.

[0010] Furthermore, the leveling rollers on the same leveling line are connected in parallel through a fixed frame, and the leveling rollers on the upper leveling line move up and down together with the upper platform.

[0011] In the device, the servo motor is connected to a control computer. The servo motor transmits the deformation pressure signal of the leveling roller to the control computer, and the control computer includes controlling the power transmission and movement of the electromagnetic brake.

[0012] Based on the above leveling device, the present invention also provides a servo-driven sheet leveling control method, including the following steps:

[0013] (1) Convey the sheet from one end to the leveling device. The servo motor controls the upper crossbeam to lift to a height of H0. The control computer collects the deformation data of the sheet through the servo motor until the end of the sheet leaves the leveling roller; the height H0 is an initial value set according to the requirements of sheet leveling.

[0014] (2) The control computer divides the deformation data obtained by inputting the whole sheet into data segments corresponding to the leveling units on the leveling line. The leveling units include a single leveling roll or several leveling rolls.

[0015] (3) Calculate the torque output of each servo motor on the leveling line according to the finite element analysis model, and then level the sheet.

[0016] Further, in the process of detecting the deformation data of the sheet, step (1) includes controlling the tilt angle of the upper platform of the device by adjusting the tilt angle adjustment screw, and cooperating with the servo motor at the corresponding position to obtain the data of different stress values at different position points of the sheet passing through.

[0017] Further still, in step (2), the data segments are divided according to the time when the corresponding sheet of the deformation data passes through a single or several leveling rolls, and the width is defined as t, and the size of t is adjusted according to the thickness of the sheet and the flatness parameter to be corrected.

[0018] Beneficial effects: Compared with the existing leveling equipment, the servo-driven sheet leveling device of the present invention adopts the combined control of electromagnetic brakes and servo motors, and has higher position control accuracy than the existing hydraulic control device. It saves the storage and transportation structure of the hydraulic oil attached to the hydraulic device, making the leveling machine relatively simple; the present invention can collect the resistance information generated during leveling, provides convenience for analyzing and optimizing the leveling process, and can level sheets of various thickness specifications through beam adjustment. Description of the Drawings

[0019] Figure 1 is a schematic structural diagram of the device of the present invention;

[0020] Figure 2 is an implementation schematic diagram of the method of the present invention. Detailed Embodiment

[0021] In order to elaborate in detail the technical solutions disclosed by the present invention, the following further elaboration is made in conjunction with the accompanying drawings of the specification.

[0022] The present invention provides a servo-driven sheet leveling device for leveling operations in the sheet processing process. Most of the existing leveling machines or flattening machines adopt the hydraulic driving method, and control the lifting of the leveling rolls by hydraulic means to achieve the leveling of steel sheets of different thicknesses. Further pointed out that due to the existence of residual stress generated during the rolling stage of the sheet itself, various deformations of the sheet will occur. For the leveling process, it is crucial to control the release of stress well to make the sheet return to flatness. Forcing pressure during the leveling process will affect the metal rigidity and characteristics of the sheet to a certain extent, and will also cause the quality of the products prepared with this sheet to decline.

[0023] Combined with Figure 1 , the present invention includes a frame 1. The outside of the frame 1 is used for encapsulating into finished products and also for supporting the device. In the middle of the frame 1, an upper platform 2 and a lower platform 3 are oppositely arranged. On the upper platform 2 and the lower platform 3, there are idler rollers 4. The idler rollers 4 can be arranged side by side with rollers of the same length, or can be arranged in an orderly staggered manner with different lengths. The function of the idler rollers 4 is to support the leveling rollers 5. Therefore, in the upper and lower leveling planes formed by connecting the idler rollers 4 on the upper platform 2 and the lower platform 3 respectively, several leveling rollers 5 are arranged. The number of the leveling rollers 5 is two or more, and the number can be adjusted according to the leveling parameters and the cylinder diameter of the leveling rollers 5. The smaller the cylinder diameter of the leveling rollers 5, the more the number, and the better the leveling effect.

[0024] Several leveling rollers 5 constitute two leveling lines, namely the upper leveling line arranged on the upper platform 2 and the lower leveling line stacked on the lower platform 3. The leveling rollers 5 on the same leveling line are linked by gears, and the gears between the connected leveling rollers 5 are meshed. On the two leveling lines, the variable-frequency motor 6 is connected to the first leveling roller 5 through a transmission shaft to achieve driving, and the two leveling lines are driven by two independent variable-frequency motors 6. In order to further achieve precision control, the variable-frequency motor 6 includes a deceleration controller, and further expands the adjustable range of torque. Further, for the leveling rollers 5 on the upper leveling line and the lower leveling line, they are fixedly connected together through a fixed frame to realize the lifting movement of the whole leveling line. For the lower leveling line, it can also be stacked in a way that does not pass through the fixed frame, and the gear linkage can be achieved by its own gravity and leveling pressure, which is convenient for replacement and operation in the actual use process. For the leveling rollers 5 on the upper leveling line, it is preferred to fix the leveling rollers 5 on the whole leveling line and connect them to the upper platform 2. The lifting of the upper platform 2 can be controlled, which is also convenient for the insertion and transmission of the steel plate 14 and the handling of workpieces. For the leveling rollers 5 on the lower leveling line, chain drive is adopted to achieve the linkage on the same line.

[0025] The upper platform 2 is a structural design with adjustable height and tilt angle. It is connected to the upper cross beam 8 through the tilt angle adjustment screw 7. By adjusting the tilt angle adjustment screw 7, the horizontal height at both ends is controlled, so as to realize the tilt angle of the leveling rollers 5 in the upper leveling line fixed on the upper platform 2, so that the plate enters and exits the leveling rollers 5 to form a gradual deformation process. The leveling rollers 5 are powered by the variable-frequency motor 6, and the leveling rollers 5 are driven to rotate actively through gear transmission to generate pressure for leveling. The function of the idler rollers connected to the leveling rollers 5 is to support the leveling rollers 5 and prevent them from deforming. This design, on the one hand, controls the stress appropriately in a gradual form, and on the other hand, is convenient for the transmission, insertion and processing operations of various thickness plates.

[0026] The upper top of the upper crossbeam 8 is grooved to fix the ball nut 901, and a certain hole is opened downward from the groove for the deep penetration of the ball screw 9. The ball nut 901 and the ball screw 9 cooperate, and the ball screw 9 is connected to the rotating shaft of the servo motor 10 located on the frame 1. For better precision control, the servo motor 10 is provided with an electromagnetic brake 101. To ensure the stability of the up-and-down height adjustment of the upper crossbeam 8, the side of the upper crossbeam 8 moves along the guide rail on the inner side of the frame 1 through the cooperation of the ball slider 11 and the ball guide rail 12.

[0027] Further pointed out, the lifting position of the upper crossbeam 8 is controlled by the servo motor 10 and the electromagnetic brake 101. The servo motor 10 can not only control the height position of the upper crossbeam 8, but also collect the regional deformation resistance during the leveling process. When the upper crossbeam 8 is at a certain height, if there is a large difference in the deformation resistance value collected by the servo motor 10, the servo motor 10 will primarily adjust the corresponding height distance according to the deformation resistance value to further adjust the flatness of the sheet. The basic trend is that the greater the deformation resistance value, the servo motor 10 correspondingly reduces the appropriate height to exert excessive pressure on this part of the sheet.

[0028] Those skilled in the art should know the control of the device on the basis of combining the structure of the existing equipment and conventional technical means. The leveling device described in the present invention further includes a control computer, which mainly controls the output of leveling parameters, and can obtain the pressure change of the leveling roller 5, perceive the current or torque of the servo motor 10, especially cooperate with the electromagnetic brake 101 to obtain parameters and output values, and also includes setting pressure sensors at corresponding positions on the frame, the upper crossbeam or the upper and lower platforms to improve the use effect and leveling accuracy of the present invention.

[0029] Next, for the device described in the present invention, a process of a servo-driven sheet leveling control method will be introduced.

[0030] A servo-driven sheet leveling control method, as Figure 2 shown, includes the following steps:

[0031] (1) Convey the sheet from one end to the leveling device, the servo motor controls the upper crossbeam to lift to a height of H0, and the control computer collects the deformation data of the sheet through the servo motor until the end of the sheet leaves the leveling roller; the height H0 is an initial value set according to the requirements of sheet leveling.

[0032] In step (1), before the sheet metal is leveled, it needs to pass through the upper and lower leveling rollers of the entire leveling system in sequence as a whole, aiming to test the flatness of the sheet metal before leveling. The lifting position of the upper crossbeam is controlled by a servo motor and a braking device. The servo motor can not only control the height position of the crossbeam, but also collect the regional deformation resistance during the leveling process. When the entire sheet metal gradually passes through the leveling rollers, the servo motor on the upper crossbeam will act in coordination with the feeding of the sheet metal, and a initial height value H0 is given. Generally, the initial height value is based on the condition that the sheet metal does not produce plastic strain. At this time, the role of the servo motor is to record the stress value at the initial height value. For the height value, an initial value can be directly visually estimated or measured according to the thickness and deformation amount of the sheet metal to be leveled. Further, the tilt angle adjustment screw can be adjusted to control the tilt angle of the upper platform in the device, and cooperate with the servo motor at the corresponding position to obtain different stress value data of the sheet metal passing through different position points. For example, at the inlet section of the sheet metal transmission, the opening is larger, and at the rear end, the middle spacing of the upper and lower leveling lines has a larger opening, so as to enable the servo motor to collect different data. This data is continuous data. When the pressure generated by the sheet metal passing through the leveling rollers in sequence is continuous, and because the sheet metal is a whole piece, the data can be used to well simulate the deformation of the sheet metal. Combining the analysis of the finite element model, better control of the force (torque output of the servo motor and electromagnetic brake) can be achieved.

[0033] (2) The control computer divides the deformation data obtained by inputting the entire sheet metal into the leveling device into data segments corresponding to the leveling units on the leveling line. The leveling units include a single leveling roller or several leveling rollers.

[0034] When the sheet metal passes through the leveling rollers in the upper and lower leveling lines, the leveling rollers on the lower leveling line maintain a horizontal position under the support of the idler rollers. The leveling rollers on the upper leveling line are connected to the upper platform and the servo motor, and the electromagnetic brake of the servo motor can collect the change of the torque value. In addition, because the leveling rollers are cylindrical, the upper leveling line formed by the upper leveling rollers is wavy. When the tangent point on the outer circle of the leveling roller abuts against the sheet metal, the torque received by the servo motor is the strongest. Therefore, in the continuous data collected from the entire sheet metal, it is easy to extract the stress values of each node.

[0035] Among them, the deformation data is divided into data segments corresponding to the time when the sheet metal passes through a single or several leveling rollers. The time is converted from the rotational speed of the variable-frequency motor to the rotational speed of the leveling rollers, and then the passing time is solved. The width is defined as t, and the size of t is adjusted according to the thickness of the sheet metal and the flatness parameter to be corrected.

[0036] On the premise of the initial height value H0, the sheet metal is divided into n measurement units in the feeding direction, and the width of the unit is defined as t (such as Figure 2(3) The size of t is adjusted according to the thickness of the plate and the flatness parameter to be corrected. Generally, the range of t is 50 - 400 mm. The smaller the t value, the higher the correction accuracy.

[0037] (3) Calculate the torque output of each servo motor on the leveling line according to the finite element analysis model, and then level the plate.

[0038] This method first measures the deformation data (stress values) of the plate, and transmits the pressure through the leveling rollers to the servo motor. The control computer collects the torque values of the electromagnetic brakes of the servo motor to obtain all the data of the entire plate. Then, based on the collected deformation data converted into stress values, it calculates and controls the torque output of the servo motor and the electromagnetic brake. During the leveling process of the plate, it controls the torque values at each stage to generate corresponding resistance forces, promoting the gradual release of the stress of the plate. For the analysis and processing of stress values by finite element, there is a prior art method for detecting the sectional contact stress of cylindrical rolling elements (publication number: CN114491848A). For the servo motor and the electromagnetic brake for pressure detection, the servo motor transmits the torque back through the main shaft, sends the pressure signal to the PLC, and the PLC obtains the stress data through calculation.

[0039] Finally, under the conditions of the set initial height value and the width of the measurement unit of the servo motor, it traverses and collects the stress of each part of the plate, and calculates the original height of each part of the plate by using the finite element analysis program through superimposing the stress data. According to the original height (flatness) data of each unit of the plate and the flatness result to be leveled, it accurately outputs the magnitude of the leveling force required for each part through a calculation method, achieving the purpose of accurate leveling.

Claims

1. A servo-driven sheet leveling device, comprising a frame (1), characterized in that: In the middle of the frame (1), there are an upper platform (2) and a lower platform (3). The upper platform (2) and the lower platform (3) are both provided with idler rollers (4). A leveling roller (5) is arranged between the two groups of idler rollers (4). The leveling roller (5) is driven by a variable-frequency motor (6). The upper platform (2) is fixed on the upper cross beam (8) through an inclination angle adjusting screw (7). The inclination angle adjusting screw (7) is used to adjust the left and right inclination angles of the upper platform (2). The upper cross beam (8) is connected to a servo motor (10) located at the top of the frame (1) through a ball nut (901) and a ball screw (9). The servo motor (10) controls the descending height of the upper cross beam (8), thereby controlling the distance between the two groups of idler rollers (4). The two sides of the upper cross beam (8) are matched with ball guide rails (12) and ball sliders (11) to move up and down on the side wall of the frame (1). Two or more groups of the servo motors are provided. The servo motor (10) is connected to a control computer. The servo motor (10) transmits the deformation pressure signal of the leveling roller (5) to the control computer. The control computer includes controlling the power transmission and movement of an electromagnetic brake, and executes the following leveling control method, including the following steps: (1) Convey the sheet from one end to the leveling device. The servo motor controls the upper cross beam to lift to a height of H0. The control computer collects the deformation data of the sheet through the servo motor until the end of the sheet leaves the leveling roller. The height H0 is an initial value set according to the requirements of sheet leveling. During the detection of the sheet deformation data, it includes controlling the inclination angle of the upper platform in the device by adjusting the inclination angle adjusting screw, and cooperating with the servo motor at the corresponding position to obtain different stress value data of the sheet passing through different position points. (2) The control computer divides the deformation data obtained by inputting the whole sheet into data segments corresponding to the leveling units on the leveling line. The leveling unit includes a single leveling roller or several leveling rollers. The corresponding sheet of the deformation data is divided into data segments according to the time when it passes through a single or several leveling rollers. The width is defined as t, and the size of t is adjusted according to the thickness of the sheet and the flatness parameter to be corrected. (3) Calculate the torque output of each servo motor on the leveling line according to the finite element analysis model, and then level the sheet.

2. The servo-driven sheet flattening device according to claim 1, wherein: The leveling roller (5) is driven by a variable-frequency motor (6). The variable-frequency motor (6) is connected to the leveling roller (5) through a transmission shaft (13). A plurality of leveling rollers (5) are provided, forming two upper and lower leveling lines, and the middle is used for leveling the steel plate (14).

3. The servo-driven sheet leveling device according to claim 2, wherein: The leveling rollers (5) on the two upper and lower leveling lines are controlled by two independent variable-frequency motors (6). The variable-frequency motor (6) drives the first leveling roller (5) connected to it through a transmission shaft (13). The leveling rollers (5) on the same leveling line are meshed and linked by gears.

4. The servo-driven sheet leveling device according to claim 1, characterized in that: The servo motor (10) is connected with an electromagnetic brake (101) to control the lifting height of the upper cross beam (8).

5. The servo-driven sheet leveling device according to claim 2, characterized in that: The leveling rollers (5) located on the same leveling line are connected in parallel through a fixed frame. The leveling rollers (5) on the upper leveling line move up and down together with the upper platform.

6. The servo-driven sheet leveling device according to claim 1, wherein: In the described device, a servo motor (10) is connected to a control computer. The servo motor (10) transmits the deformation pressure signal of the leveling roller (5) to the control computer, and the control computer includes controlling the power transmission and movement of the electromagnetic brake.

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