Plate bender and plate bender control method

Abstract

The control device controls the worktable lifting mechanism to unload the metal plate (W) in such a manner that the upper worktable is raised in one or more stages during unloading of the metal plate (W) for calculating the springback amount of the metal plate (W) after the metal plate (W) is bent to a temporary bending angle. The control device determines whether or not unloading of the metal plate (W) is completed on the basis of the amount of change or the rate of change of the angle of the first flange (Wff) measured by the first angle sensor (21F) or the angle of the second flange (Wrf) measured by the second angle sensor (21R) at the time when the metal plate (W) is bent to a predetermined angle before unloading of the metal plate (W) or the immediately preceding one of the one or more stages.

Description

Technical Field

[0001] This disclosure relates to a bending machine and a method for controlling the bending machine. Background Technology

[0002] The bending machine has an upper worktable for mounting punches and a lower worktable for mounting dies. The upper worktable is lowered to the lower worktable, and the metal plate mounted on the die is clamped by the punch and the die and bent (see Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 4280332 Summary of the Invention

[0006] Even when a metal sheet is bent to the target bending angle using a bending machine, the bending angle becomes larger than the target angle due to springback. Therefore, in order to bend the metal sheet to the target bending angle, the springback must be taken into account, and the metal sheet must be bent at a smaller bending angle than the target bending angle.

[0007] Thus, in order to bend the metal sheet to the desired target bending angle using a bending machine, a load removal action is required to calculate the springback amount. The load removal period for calculating the springback amount is one of the additional times beyond the actual bending time required within the series of steps from the start to the completion of bending the metal sheet. Sometimes, other additional times are also needed within this series of steps. These additional times within the series of bending steps are a major reason for the extended processing time comprised of these steps. It is desirable to minimize the processing time when bending metal sheets.

[0008] A first embodiment of one or more implementations provides a bending machine, comprising: an upper worktable on which a punch is mounted; a lower worktable on which a die is mounted; a worktable lifting mechanism for raising or lowering the upper or lower worktable; a first angle sensor and a second angle sensor, wherein, when the metal plate is bent by raising or lowering the upper or lower worktable via the worktable lifting mechanism while the metal plate is clamped by the punch and the die, the first angle sensor measures the angle of a first flange of the metal plate relative to the front side of the punch and the die, and the second angle sensor measures the angle of a second flange of the metal plate relative to the rear side of the punch and the die; and a control device that calculates the bending angle of the metal plate based on the angles of the first flange and the second flange measured by the first and second angle sensors, and controls the bending of the metal plate by the upper or lower worktable. When the control device controls the lifting mechanism of the upper or lower worktable to bend the metal plate to a predetermined angle by lowering the upper worktable or raising the lower worktable, and then controls the lifting mechanism to unload the load on the metal plate by raising the upper worktable by one or more stages or lowering the lower worktable by one or more stages, it determines whether the unloading of the metal plate is complete based on the change or rate of change of the angle of the first flange measured by the first angle sensor or the angle of the second flange measured by the second angle sensor during the lifting of the upper or lower worktable. This is done in the latest stage of the one or more stages, at the moment when the metal plate is bent to the predetermined angle before unloading the load, or in the previous stage of the one or more stages.

[0009] A second embodiment of one or more implementations provides a method for controlling a bending machine, wherein a control device controls the bending machine, the bending machine comprising: an upper worktable on which a punch is mounted; a lower worktable on which a die is mounted; a worktable lifting mechanism for raising or lowering either the upper or lower worktable; a first angle sensor and a second angle sensor, wherein when the metal plate is bent by raising or lowering the upper or lower worktable via the worktable lifting mechanism while the metal plate is clamped by the punch and the die, the first angle sensor measures the angle of a first flange of the metal plate relative to the front side of the punch and the die, and the second angle sensor measures the angle of a second flange of the metal plate relative to the rear side of the punch and the die. After bending the metal plate to a predetermined angle by controlling the worktable lifting mechanism to lower the upper worktable or raise the lower worktable, and then unloading the metal plate by controlling the worktable lifting mechanism to raise the upper worktable by one or more stages or lower the lower worktable by one or more stages, the device determines whether the unloading of the metal plate is complete based on the amount or rate of change of the angle of the first flange measured by the first angle sensor or the angle of the second flange measured by the second angle sensor.

[0010] According to one or more embodiments, the bending machine and bending machine control method can shorten the processing time when bending metal plates. Attached Figure Description

[0011] Figure 1 It is a diagram showing the overall structure of a bending machine involved in one or more embodiments.

[0012] Figure 2 This is a diagram illustrating an example of the structure of an angle sensor included in one or more embodiments of a bending machine.

[0013] Figure 3 It means Figure 2 The diagram shows the angle of the metal plate detected by the angle sensor.

[0014] Figure 4 This is an example of the control operation of the NC device of a bending machine according to one or more embodiments, and is a diagram showing a state in which the additional time required for bending the metal plate is shortened beyond the time actually required by the bending machine according to one or more embodiments, without using a unique time-shortening method.

[0015] Figure 5 This diagram illustrates an example of the measured values ​​of the punch's front end position, the angles of the front and rear flanges, and the bending angle of the metal sheet when the NC device controls the table lifting mechanism to lower and raise the upper worktable in order to perform bending processing on the metal sheet.

[0016] Figure 6A This is a conceptual diagram representing the change in state of a bent metal plate from tilting forward to tilting backward due to the removal of the load.

[0017] Figure 6B This is a conceptual diagram representing the change in state of a bent metal plate from tilting backward to tilting forward due to the removal of the load.

[0018] Figure 6C This is a conceptual diagram representing the state in which a bent metal plate, due to the removal of its load, changes from a state of tilting towards the rearward side to a state of increasing tilt towards the rearward side.

[0019] Figure 7 This is an example of the control operation of the NC device of a bending machine according to one or more embodiments, and is a diagram showing the state after the additional time required to actually bend the metal plate is shortened by the unique time-shortening method performed by the bending machine according to one or more embodiments.

[0020] Figure 8 It is a flowchart illustrating the operation of a bending machine according to one or more embodiments and the control method of a bending machine according to one or more embodiments.

[0021] Figure 9 It means Figure 8 The flowchart shows the specific processing steps S3 and S8.

[0022] Figure 10 This is a diagram illustrating a preferred first example of the control operation of the NC device provided by a bending machine according to one or more embodiments.

[0023] Figure 11 This is a second preferred example of the control operation of the NC device of a bending machine according to one or more embodiments.

[0024] Figure 12 This is a diagram illustrating a preferred third example of the control operation of the NC device provided in one or more embodiments of the bending machine. Detailed Implementation

[0025] Hereinafter, a bending machine and a bending machine control method according to one or more embodiments will be described with reference to the accompanying drawings.

[0026] Figure 1 This refers to the overall structure of the bending machine 100 according to one or more embodiments. For example... Figure 1 As shown, the bending machine 100 includes an NC (Numerical Control) device 10 that functions as a control device for controlling the bending machine 100. The NC device 10 is connected to a machining program database 50 via a network. The bending machine 100 includes an upper worktable 1, a lower worktable 3, and left and right side plates 5R and 5L. An upper mold support 2 is mounted on the upper worktable 1, and a lower mold support 4 is mounted on the lower worktable 3.

[0027] The upper worktable 1 is configured to be raised and lowered by hydraulic cylinders 6L and 6R arranged on the left and right sides. Hydraulic cylinders 6L and 6R are referred to as the worktable lifting mechanism 6. The worktable lifting mechanism 6 sometimes includes actuators other than the hydraulic cylinders 6L and 6R. The worktable lifting mechanism 6 causes the upper worktable 1 to descend closer to the lower worktable 3 or rise further away from the lower worktable 3.

[0028] A punch Tp, serving as the upper die, is mounted on the upper die support 2, and a die Td, serving as the lower die, is mounted on the lower die support 4. Figure 1 The diagram shows a modular type where the upper mold support 2 is integrally mounted along the entire length of the lower end of the upper worktable 1. However, it can also be a type where multiple intermediate plates for mounting the punch Tp are provided along the length of the lower end of the upper worktable 1. The intermediate plates also serve as the upper mold support.

[0029] Installing a punch Tp on the upper worktable 1 means installing the punch Tp on the upper mold support 2 or the intermediate plate. Installing a die Td on the lower worktable 3 means installing the die Td on the lower mold support 4. Sometimes two or more punches Tp are arranged and installed on the upper worktable 1, and sometimes two or more dies Td are arranged and installed on the lower worktable 3.

[0030] A reverse travel limiter 40 is disposed on the rear side of the lower worktable 3. The reverse travel limiter 40 has abutment members 42a and 42b that move in the left-right direction along the reverse travel limit bracket 41. Here, abutment members 42a and 42b are provided, but the number of abutment members is not limited to two. Abutment members 42a and 42b are configured to move in both the height direction and the front-back direction.

[0031] Before the operator places the metal sheet W, the object of processing, on the die Td and bends it by clamping the metal sheet W with the punch Tp and the die Td, the abutments 42a and 42b move to positions corresponding to the die Td. The operator positions the inner end of the metal sheet W on the die Td by abutting it against the abutments 42a and 42b. That is, the abutments 42a and 42b function in a way that determines the front-to-back position of the metal sheet W when it is placed on the die Td.

[0032] On the left side of the bending machine 100, an operator 7 is provided via arm 7a, having a display 71 and an operation section 72 containing multiple operation buttons. The operator 7 is connected to the NC device 10. A foot switch 8 is connected to the NC device 10, which has an open foot switch 81 for raising the upper worktable 1 and an closed foot switch 82 for lowering the upper worktable 1.

[0033] Figure 2 This illustrates the structure of the angle sensor included in the bending machine 100. Although in Figure 1 The illustration is omitted, but as shown Figure 2 As shown, the bending machine 100 includes angle sensors 21F and 21R for measuring the angle of the metal sheet W when it is bent. Angle sensor 21F is a first angle sensor, and angle sensor 21R is a second angle sensor. Angle sensor 21F is positioned in front of the die Td, and angle sensor 21R is positioned behind the die Td. Angle sensors 21F and 21R are so-called contact angle sensors. Figure 2 In the example shown, angle sensors 21F and 21R are configured close to the die Td. Angle sensors 21F and 21R can also be configured at a position separate from the die Td.

[0034] Angle sensors 21F and 21R are configured to be raised and lowered via sensor lifting mechanisms 22F and 22R, respectively. When it is necessary to measure the angle of the metal plate W, the lower angle sensors 21F and 21R are moved upward via sensor lifting mechanisms 22F and 22R under the control of the NC device 10.

[0035] Angle sensors 21F and 21R each have a main body 211 and a protrusion 212 that is movable relative to the main body 211. A slightly protruding front end portion 213 is provided at the upper end of the protrusion 212. Figure 2 In the state before the processing of the bent metal plate W is started, the protrusions 212 of the angle sensors 21F and 21R are in the least protruding state. Figure 3 This indicates the angle of the metal plate W detected by angle sensors 21F and 21R. For example... Figure 3As shown, when the punch Tp descends and the metal plate W bends, the protrusion 212 protrudes upward in a corresponding manner to the upward displacement of the metal plate W.

[0036] like Figure 3 As shown, angle sensor 21F measures the angle θf between the back of the front flange Wff on the front side of the metal plate W (as indicated by the dashed line) and the center line of the punch Tp and die Td. Angle sensor 21R measures the angle θr between the back of the rear flange Wrf on the rear side of the metal plate W (as indicated by the punch Tp and die Td) and the center line of the punch Tp and die Td. The front flange Wff is the first flange, and the rear flange Wrf is the second flange. Figure 2 As shown, the angles θf and θr measured by angle sensors 21F and 21R are input to the NC device 10. The NC device 10 calculates by adding angle θf and angle θr. Figure 3 The bending angle θw of the metal plate W shown.

[0037] The angle sensor for measuring the angle of the metal plate W is not limited to a contact angle sensor; it can also be a laser angle sensor. When using a laser angle sensor, sensor lifting mechanisms 22F and 22R are not required, and the front and rear laser angle sensors are positioned in a fixed vertical direction. The front and rear laser angle sensors have a laser emitting section that irradiates a linear laser beam onto the back of the front flange Wff and the rear flange Wrf, and an imaging section that captures the irradiated linear laser beam. The NC device 10 calculates the angles θf and θr based on the angle of the linear laser beam in the image captured by the imaging section, and then calculates the bending angle θw of the metal plate W.

[0038] In the bending machine 100 configured as described above, the NC device 10 controls the bending machine 100 to bend the metal plate W in accordance with the processing program stored in the processing program database 50.

[0039] Figure 4 This represents an example of the control action of the NC device 10. Figure 4 The diagram illustrates a state where the additional time required for bending the metal sheet W, beyond the actual bending time, is reduced by a unique time-shortening method not performed by the bending machine 100, such as during the load removal period for calculating springback. Figure 4 In the diagram, the horizontal axis represents time, and the vertical axis represents the position of the tip of the punch Tp in the height direction. Figure 4To easily understand the change in the height of the punch tip Tp, the distance between position R3 and position F3 is shown in a magnified view. The distance from position R3 to position F3 is approximately 0.1mm to 0.2mm. Furthermore, the distance from the contact position (described later) to position F3 is approximately 2mm to 3mm.

[0040] The target bending angle of the metal plate W is, for example, 90 degrees. NC device 10, as shown... Figure 4 The upper worktable 1 is raised and lowered as shown to bend the metal plate W to a target bending angle of 90 degrees. When the NC device 10 begins to lower the upper worktable 1, the tip of the punch Tp contacts the metal plate W. The NC device 10 positions the upper worktable 1 at the point where the tip of the punch Tp is... Figure 4 Stop when the contact position is reached, so that the abutment parts 42a and 42b are separated from the metal plate W.

[0041] During the temporary bending process after the tip of the punch Tp contacts the metal plate W, the NC device 10 lowers the tip of the punch Tp to position T1 and temporarily stops it, then lowers it to position T2. Figure 4 In the middle, the upper worktable 1 (punch Tp) is lowered by 2 stages, but the number of stages of descent is not limited to 2 stages.

[0042] Position T2 during the temporary bending is the position used to bend to a predetermined temporary bending angle larger than 90 degrees, which is the target bending angle. During the temporary bending, the NC device 10 controls the table lifting mechanism 6 to lower the upper table 1 to a first depth value for bending the metal plate W to the temporary bending angle. The first depth value of the punch Tp, used to bend the metal plate W to the temporary bending angle after the tip of the punch Tp contacts the metal plate W, is predetermined based on bending theory. The depth value refers to the amount of descent of the punch Tp when the tip of the punch Tp contacts the metal plate W, based on the contact position. That is, the depth value represents the position of the tip of the punch Tp in the height direction. Hereinafter, the depth value will be abbreviated as D value.

[0043] When the temporary bending action is completed, the NC device 10 calculates the first bending angle θw1 as the bending angle θw of the metal plate W based on the angles θf and θr of the front flange Wff and the rear flange Wrf measured by the angle sensors 21F and 21R. The NC device 10 maintains the first bending angle θw1 when the temporary bending action of the metal plate W is completed.

[0044] If the bending of the metal plate W is a temporary bending angle, the NC device 10 moves the bending machine 100 to the load removal period for calculating the springback. During load removal, the NC device 10 controls the upper worktable 1 to rise sequentially in multiple stages to maintain contact between the punch Tp and the metal plate W, and to remove the load from the metal plate W. Load removal refers to removing the load applied to the metal plate W.

[0045] exist Figure 4 In the process, the NC device 10 raises the tip of the punch Tp to position R1 and temporarily stops it, calculating the bending angle θw of the metal plate W based on the angles θf and θr measured by angle sensors 21F and 21R. Next, the NC device 10 raises the tip of the punch Tp to position R2 and temporarily stops it, calculating the bending angle θw of the metal plate W again. If the difference between the bending angle θw(R1) at position R1 and the bending angle θw(R2) at position R2 is within a threshold value, then the unloading of the metal plate W is complete. Figure 4 This example illustrates an instance where the difference between the bending angle θw(R1) and the bending angle θw(R2) at position R2 is not within a threshold value, thus indicating that the unloading of the metal plate W is incomplete.

[0046] Thus, during the multiple stages of load unloading of the metal plate W, it is possible to determine whether the load unloading of the metal plate W is complete based on whether the difference between the bending angle θw of the metal plate W at the position immediately preceding the tip of the punch Tp and the bending angle θw of the metal plate W at the position of the latest stage is within a threshold. The method for determining whether the load unloading of the metal plate W is complete based on this bending angle θw is a conventionally used method.

[0047] The NC device 10 raises the tip of the punch Tp to position R3 and temporarily stops it, calculating the bending angle θw of the metal plate W. If the difference between the bending angle θw(R2) at position R2 and the bending angle θw(R3) at position R3 is within a threshold, the NC device 10 determines that the load removal of the metal plate W has been completed at position R3. Furthermore, the stage at which the NC device 10 determines the completion of the load removal of the metal plate W will vary depending on various conditions, such as the distance from position T2 to position R1, the distance from position R1 to position R2, and the distance from position R2 to position R3.

[0048] During load removal, with the metal plate W unloaded, the NC device 10 calculates a second bending angle θw2 as the bending angle θw of the metal plate W based on the angles θf and θr measured by angle sensors 21F and 21R. Even if the metal plate W is bent at a first bending angle θw1 during temporary bending, the bending angle increases due to springback if the load is removed during load removal. The second bending angle θw2 is the bending angle θw of the metal plate W after springback. The NC device 10 calculates the springback amount by subtracting the first bending angle θw1 from the second bending angle θw2.

[0049] If a springback amount is obtained during load removal based on the difference between the second bending angle θw2 and the first bending angle θw1, the NC device 10 moves the bending machine 100 to the follow-up phase. The NC device 10 calculates a second D value, taking into account the springback amount, for bending the metal plate W towards the target bending angle. If the springback amount is simply set to, for example, 2 degrees, then considering setting the target bending angle to 88 degrees, the amount of descent required to bend the metal plate W at a bending angle of 88 degrees when the upper worktable 1 is lowered is considered. However, the springback amount usually varies depending on the target bending angle, so even if the springback amount obtained during load removal is used directly to set the target bending angle, it may not always result in the target bending angle of 90 degrees.

[0050] Therefore, the NC device 10 can calculate a second D value for bending the metal plate W to the set target bending angle based on the springback amount obtained during load removal, instead of directly using the springback amount obtained during load removal.

[0051] During the follow-up process, the NC device 10 controls the table lifting mechanism 6 by dividing the second D value into multiple segments, causing the upper table 1 to descend sequentially in multiple stages by the second D value. Figure 4 In the process, the NC device 10 lowers the position of the tip of the punch Tp from position R3 to position F1 and temporarily stops it, calculating the bending angle θw of the metal plate W. Next, considering the bending angle at position F1, the NC device 10 lowers the position of the tip of the punch Tp to position F2 and temporarily stops it, calculating the bending angle θw of the metal plate W again. Finally, considering the bending angle at position F2, the NC device 10 lowers the position of the tip of the punch Tp to position F3, where the final bending angle of the metal plate W becomes the target bending angle of 90 degrees.

[0052] Here, the follow-up actions during the follow-up period are defined as three stages, but it can be one stage, two stages, or even four or more stages. The number of stages for the follow-up actions is not limited.

[0053] If the metal plate W is bent to the target bending angle, the NC device 10 transfers the bending machine 100 to the final angle measurement period. The NC device 10 maintains the state of contact between the punch Tp and the metal plate W and removes the load from the metal plate W, and calculates the final bending angle θw of the metal plate W based on the angles θf and θr measured by the angle sensors 21F and 21R.

[0054] exist Figure 4 In the process, the NC device 10 raises the tip of the punch Tp to position L1 and temporarily stops it, calculating the bending angle θw of the metal plate W. Next, the NC device 10 raises the tip of the punch Tp to position L2 and temporarily stops it, calculating the bending angle θw of the metal plate W again. Similar to the load removal process, if the difference between the bending angle θw(L2) at position L2 and the bending angle θw(L1) at position L1 is within a threshold, then the load removal of the metal plate W is complete. If the difference between the bending angle θw(L2) at position L2 and the bending angle θw(L1) at position L1 is within a threshold, then the NC device 10 determines that the load removal of the metal plate W has been completed at position L2.

[0055] With the metal plate W unloaded, the NC device 10 calculates the final bending angle θw of the metal plate W. Then, the NC device 10 controls the table lifting mechanism 6 to raise the upper table 1.

[0056] Next, the explanation is as follows: Figure 4 The control operation of the NC device 10 shown uses a unique time-shortening method executed by the bending machine 100, which reduces the additional time during the load removal period for calculating the rebound amount. Figure 5 The NC device 10 is shown to be connected with Figure 4 Similarly, the measured values ​​of the position of the punch Tp's tip, the angles θf and θr of the front flange Wff and rear flange Wrf, and the bending angle θw of the metal plate W are obtained when the upper worktable 1 is lowered and raised to control the worktable lifting mechanism 6. A thick solid line represents the position of the punch Tp's tip, a thin solid line represents the bending angle θw, a single-dot dashed line represents angle θf, and a dashed line represents angle θr. However, the height direction of the waveform representing the bending angle θw of the metal plate W is offset between angles θf and θr to facilitate understanding of its acquisition through angles θf and θr. The bending angle θw is obtained by adding angles θf and θr.

[0057] exist Figure 5In the process, at position R1 during load removal, the angle θf of the metal plate W is larger than the angle θr. However, at position R2, the angle θr is greater than the angle θf, and the relationship between the two angles is reversed. Thus, a significant change in the angle θf or θr of the metal plate W indicates that load removal has actually been completed at position R2. Let the angles θf and θr of the immediate stage during load removal be denoted as angles θf(n-1) and θr(n-1), respectively. Let the angles θf and θr of the latest stage during load removal be denoted as angles θf(n) and θr(n), respectively.

[0058] The NC device 10 can determine that the unloading of the metal plate W is complete as long as at least one of the following conditions is met: a first condition where the absolute value of the angle difference between angle θf and angle θf(n-1) exceeds a predetermined value, and a second condition where the absolute value of the angle difference between angle θr(n) and angle θr(n-1) exceeds a predetermined value. Whether the first condition or the second condition is met can be determined as follows.

[0059] The NC device 10 determines that the unloading of the metal plate W is complete when either equation (1) or equation (2) is satisfied. The first threshold Δθfth and the second threshold Δθrth can be the same value or different values. The first threshold Δθfth and the second threshold Δθrth are thresholds for the angle difference. Alternatively, during a phase of unloading, the NC device 10 determines that the unloading of the metal plate W is complete when both equation (1) and equation (2) are satisfied. Equation (1) is a first determination equation using the angle difference between angle θf(n) and angle θf(n-1), and equation (2) is a second determination equation using the angle difference between angle θr(n) and angle θr(n-1).

[0060]

[0061] The NC device 10 can also use equations (3) to (6) instead of equation (1) or equation (2) to determine whether the unloading of the metal plate W is complete. Equation (3) represents the ratio Ratioθf of angle θf(n) to angle θf(n-1), and equation (4) represents the ratio Ratioθr of angle θr(n) to angle θr(n-1). The NC device 10 can determine that the unloading of the metal plate W is complete as long as at least one of the following conditions is met: the absolute value obtained by subtracting the ratio Ratioθf from 1 exceeds the third threshold Ratioθfth, and the absolute value obtained by subtracting the ratio Ratioθr from 1 exceeds the fourth threshold Ratioθrth. The third threshold Ratioθfth and the fourth threshold Ratioθrth can be the same value or different values. The third threshold Ratioθfth and the fourth threshold Ratioθrth are thresholds for the ratio of changing angles (angle change ratio). The NC device 10 can also determine that the load removal of the metal plate W is completed when both equations (5) and (6) are satisfied.

[0062]

[0063] Equations (3) and (5) are the third criteria that use the ratio of angle θf(n) to angle θf(n-1). Equations (4) and (6) are the fourth criteria that use the ratio of angle θr(n) to angle θr(n-1).

[0064] The NC device 10 can also use equation (8) to determine whether the unloading of the metal plate W is complete when equation (7) is satisfied, and use equation (10) to determine whether the unloading of the metal plate W is complete when equation (9) is satisfied. Equations (8) and (10) are formulas for determining whether the unloading of the metal plate W is complete based on the angle difference between the angle θf of the front flange Wff and the angle θr of the rear flange Wrf. If the value obtained by subtracting the angle θr(n) from the angle θf(n) is less than the fifth condition of the fifth threshold Δθfr, or if the value obtained by subtracting the angle θf(n) from the angle θr(n) is less than the sixth condition of the fifth threshold Δθfr, then the NC device 10 can determine that the unloading of the metal plate W is complete. The fifth threshold Δθfr is the threshold of the angle difference.

[0065]

[0066] Equations (7) to (10) are the fifth determination formulas that use the relationship between angles θf(n-1) and θr(n-1) and the angle difference between angles θf(n) and θr(n).

[0067] Furthermore, the NC device 10 can also use equations (11) to (13) to determine whether the unloading of the metal plate W is complete. The bending angle θw of the immediate preceding stage during the unloading period is set as bending angle θw(n-1), and the bending angle θw of the latest stage during the unloading period is set as bending angle θw(n). The value obtained by subtracting the ratio of angle θr(n-1) to bending angle θw(n-1) from the ratio of angle θf(n-1) to bending angle θw(n-1) is set as Ratioθ(n-1). The value obtained by subtracting the ratio of angle θrn to bending angle θwn from the ratio of angle θfn to bending angle θwn is set as Ratioθn. If the absolute value of the difference between the value Ratioθ(n-1) and the value Ratioθn exceeds the seventh condition of the sixth threshold ΔRatioθ, the NC device 10 can determine that the unloading of the metal plate W is complete. The sixth threshold ΔRatioθ is a threshold for the angle change ratio.

[0068]

[0069] Equations (11) to (13) are the sixth determination formulas that use the ratios of angle θf(n-1) to bending angle θw(n-1), angle θr(n-1) to bending angle θw(n-1), angle θf(n) to bending angle θw, and angle θr(n) to bending angle θw.

[0070] exist Figure 6A as well as Figure 6B In the diagram, the metal plate W indicated by the double-dotted line exaggerates its position during the immediate preceding stage of load removal, while the metal plate W indicated by the solid line exaggerates its position during the most recent stage of load removal. (See diagram for reference.) Figure 5 As in the example at position R2, the relationship between the magnitudes of angles θf and θr is reversed. Figure 6A or Figure 6B Therefore, the bent metal plate W can change from a state tilted towards the front to a state tilted towards the rear, or from a state tilted towards the rear to a state tilted towards the front.

[0071] Figure 6A as well as Figure 6B Examples are shown of metal plate W changing from a state of tilting towards the front to a state of tilting towards the rear, or vice versa. Unlike these, such as... Figure 6C As exaggerated, there are cases where the metal plate W tilts from the front or rear side, and the tilt increases further. In particular, if there is a large difference between the length of the front flange Wff and the length of the rear flange Wrf, the tilt may increase due to the difference in the weight of the flanges. Figure 6CThis illustrates a situation where the length of the rear flange Wrf is longer than the length of the front flange Wff, and the metal plate W tilts further towards the rear from a state of tilting towards the rear.

[0072] Depend on Figure 5 As shown by the thin solid lines at positions R2 and R3, the bending angle θw of the metal plate W is almost unchanged at positions R2 and R3. This proves that the load removal of the metal plate W was completed at position R2. According to the commonly used method for determining whether the load removal of the metal plate W is complete based on the bending angle θw, such as... Figure 5 As shown, since there is a predetermined difference between the bending angle θw(R1) and the bending angle θw(R2), it is determined that the load removal of the metal plate W at position R2 has not been completed.

[0073] In contrast, a new determination method, which uses at least one of the first to sixth determination equations executed by the bending machine 100 to determine whether the unloading of the metal plate W is complete, can determine that the unloading of the metal plate W at position R2 is complete. That is, if the new determination method executed by the bending machine 100 is used, it is not necessary to set... Figure 4 The phase of position R3 during the unloading process is shown.

[0074] Furthermore, in Figure 5 In the final stage of the follow-up period, at position F2, angle θf is greater than angle θr. However, at position L1 during the final angle measurement period, angle θr is greater than angle θf, and the relationship between angles θf and θr is reversed. Therefore, at position L1 during the final angle measurement period, either angle θf or θr changes significantly, so the load removal is actually completed at position L1. During the final angle measurement period, the NC device 10, similarly to the load removal period, can use at least one of the first to sixth decision equations to determine whether the load removal of the metal plate W is complete.

[0075] However, if the angles θf and θr at position L1 during the final angle measurement period are set as the angles θf(n) and θr(n) of the latest stage, then position F2 (at the last stage of the follow-up period) Figure 4 The angles θf and θr at position F3 are called the angles θf(n-1) and θr(n-1) of the immediate preceding stage.

[0076] Depend on Figure 5The bending angle θw of the metal plate W at positions L1 and L2 shows that there is almost no change in the bending angle θw at positions L1 and L2. This is proof that the load removal of the metal plate W has been completed at position L1. According to the commonly used method for determining whether the load removal of the metal plate W is complete based on the bending angle θw, such as... Figure 5 As shown, there is a large difference between the bending angle θw at position F2 and the bending angle θw at position L1. Therefore, it is determined that the load removal of the metal plate W at position L1 has not been completed.

[0077] In contrast, according to the new determination method executed by the bending machine 100, it can be determined that the load removal of the metal plate W at position L1 is complete. That is, if the new determination method executed by the bending machine 100 is used, it is not necessary to set... Figure 4 The stage of position L2 during the final angle measurement shown.

[0078] As mentioned above, if the new judgment method is used by the bending machine 100, then it is not necessary to set... Figure 4 The diagram shows the phase at position R3 during load removal and the phase at position L2 during final angle measurement. Therefore, the NC device 10 only needs to... Figure 7 The control action shown does not involve positions R3 and L2. (Comparison) Figure 4 and Figure 7 It can be seen that if the new judgment method executed by the bending machine 100 is used, the load removal period required to calculate the springback amount can be shortened, and the final angle measurement period for calculating the final bending angle θw of the metal plate W can be shortened.

[0079] Figure 7 The example shown could determine that the unloading of metal plate W was completed at position R2 during the unloading period, but the unloading of metal plate W was completed at position R1 in the initial stage of the unloading period. If the NC device 10 determines, using at least one of the first to sixth decision equations, that the unloading of metal plate W is completed at position T2 in the final stage of the temporary bending period and at position R1 in the initial stage of the unloading period, the stage at position R2 is not set, and the process transitions to the follow-up stage. In this case, the angles θf and θr at position R1 during the unloading period are the angles θf(n) and θr(n) of the latest stage, and the angles θf and θr at position T2, which is the final stage of the temporary bending period, are the angles θf(n-1) and θr(n-1) of the preceding stage.

[0080] If the new judgment method executed by the bending machine 100 is used, the additional time required for bending the metal sheet W, excluding the actual bending time, can be shortened within the series of steps in bending the metal sheet W. This includes the load removal period for calculating the springback amount and the final angle measurement period for calculating the final bending angle θw of the metal sheet W. By using the new judgment method executed by the bending machine 100, a reduction of several hundred milliseconds in the load removal period is expected. A reduction in time can also be expected during the final angle measurement period. According to the bending machine 100, the processing time for bending the metal sheet W can be shortened.

[0081] Furthermore, setting a final angle measurement period to calculate the final bending angle θw of the metal plate W is not necessary and is sometimes omitted. In this case, it is possible to shorten only the load removal period. If a final angle measurement period is set, the operator does not need to use, for example, a digital bending angle gauge to measure whether the metal plate W has actually been bent to the target bending angle.

[0082] use Figure 8 and Figure 9 The flowchart shown illustrates the actions of the bending machine 100 and the bending machine control method executed by the bending machine 100. Figure 8 In the process of starting the bending process, in step S1, the NC device 10 controls the table lifting mechanism 6 to lower the upper worktable 1 by a first D value, so as to bend the metal plate W to a predetermined temporary bending angle larger than the target bending angle. In step S2, the NC device 10 calculates the first bending angle θw1 of the metal plate W.

[0083] In step S3, the NC device 10 controls the worktable lifting mechanism 6 to raise the upper worktable 1 until the load on the metal plate W is unloaded. In step S4, the NC device 10 calculates the second bending angle θ2 of the metal plate W. In step S5, the NC device 10 calculates the springback amount based on the difference between the second bending angle θw2 and the first bending angle θw1. In step S6, the NC device 10 calculates the second D value of the upper worktable 1 used to bend the metal plate W to the target bending angle, taking into account the springback amount.

[0084] In step S7, the NC device 10 controls the table lifting mechanism 6 to lower the upper table 1 by one or more stages based on the second D value, bending the metal plate W to the target bending angle. In step S8, the NC device 10 controls the table lifting mechanism 6 to raise the upper table 1 until the load on the metal plate W is unloaded. In step S9, the NC device 10 calculates the final bending angle of the metal plate W. In step S10, the NC device 10 raises the upper table 1 to end the bending process.

[0085] Figure 9The specific processing of steps S3 and S8 is explained. Here, we take the case where equation (1) is used as the first decision equation or equation (2) is used as the second decision equation as an example. Step S3 consists of steps S31 and S32, and step S8 consists of steps S81 and S82. The NC device 10 then... Figure 8 In step S2 or S7, in step S31 or S81, the worktable lifting mechanism 6 is controlled to raise the upper worktable 1 by one stage. In step S32 or S82, the NC device 10 determines whether equation (1) or equation (2) is satisfied. If equation (1) or equation (2) is not satisfied (No), the NC device 10 repeats steps S31 or S81 and S32 or S82. If equation (1) or equation (2) is satisfied (Yes), the NC device 10 transfers the processing to... Figure 8 Step S4 or S9.

[0086] As described above, the bending machine 100 removes the load from the metal plate W during the temporary bending period (when bending the metal plate W to a predetermined temporary bending angle larger than the target bending angle), during the load removal period (when the metal plate W is bent to the temporary bending angle), and during the final angle measurement period (when bending the metal plate W to the target bending angle), when bending the metal plate W to the target bending angle. At this time, the NC device 10 determines whether the load removal of the metal plate W is complete based on the change in the angle of the front flange Wff measured by the angle sensor 21F or the change in the angle of the rear flange Wrf measured by the angle sensor 21R, at the latest stage of one or more stages and at the moment before the load is removed from the metal plate W, or at the stage immediately preceding one or more stages.

[0087] NC device 10 is preferably in Figure 7 Such control actions Figures 10-12 Control the lifting mechanism of the worktable as shown in Figure 6.

[0088] exist Figure 10 In this example, the rise of the upper worktable 1 from position T2 at the end of the temporary bending period to position R1 immediately before the completion of unloading of the metal plate W (i.e., position R2) is set as UR1. The initial rise of the upper worktable 1 during the final angle measurement period, i.e., from position F3 at the end of the follow-up period to position L1, is set as UL1. As a first example, the rise UR1 can be set as the rise UL1. If the rise of the upper worktable 1 is set to the initial rise of the upper worktable 1 during the final angle measurement period in order to perform unloading up to the stage before the completion of unloading of the metal plate W during the unloading period, the time required for unloading during the final angle measurement period can be shortened.

[0089] Figure 10 An example is shown where the final angle measurement is performed during the two phases at positions L1 and L2, but with... Figure 7 Similarly, the final angle measurement period could potentially be a single phase, namely position L1. The first example can be used for cases where there are at least two phases during load removal.

[0090] exist Figure 11 In this example, the rise of the upper worktable 1 from position T2 at the tip of the punch Tp at the end of the temporary bending period to position R2 at which the load is removed from the metal plate W is set as UR2. As a second example, k can be obtained by multiplying the rise UR2 by a predetermined coefficient k less than 1. The rise amount of UR2 is set to the rise amount UL1. If the rise amount of the upper worktable 1 is reduced by a predetermined ratio to the initial rise amount of the upper worktable 1 during the final angle measurement period in order to perform load removal up to the stage where the load removal of the metal plate W is completed during the load removal period, the time required for load removal during the final angle measurement period can be shortened.

[0091] Figure 11 An example is shown where the final angle measurement is divided into two phases, L1 and L2, but with... Figure 7 Similarly, the final angle measurement period may be the position L1 stage.

[0092] like Figure 12 As shown, as a third example, the rise amount UR2 can also be set to the rise amount UL1. If the rise amount of the upper worktable 1 is set to the initial rise amount of the upper worktable 1 during the final angle measurement period in order to perform load removal up to the stage where the load removal of the metal plate W is completed during the load removal period, the time required for load removal during the final angle measurement period can be shortened. Figure 12 An example is shown where the final angle measurement period is set to one stage, namely position L1, but it is possible to have more than two stages.

[0093] As in the first to third examples above, the initial rise of the upper worktable 1 during the final angle measurement period can be set based on the rise of the upper worktable 1 up to the stage before the unloading of the metal plate W is about to be completed, or up to the stage before the unloading of the metal plate W is completed. In this way, the combined effects of the reduction in processing time achieved by adopting the new method for determining whether the unloading of the metal plate W is completed can be obtained, as well as the reduction in processing time achieved by adopting the first to third examples.

[0094] This invention is not limited to the one or more embodiments described above, and various modifications can be made without departing from the spirit of the invention. In one or more embodiments described above, the upper worktable 1 is configured as a sliding worktable capable of being raised and lowered, and the lower worktable 3 is configured as a fixed worktable with a fixed position. However, the upper worktable 1 can also be configured as a fixed worktable, and the lower worktable 3 as a sliding worktable. In this case, the worktable lifting mechanism 6 raises and lowers the lower worktable 3. The rising and falling of the upper worktable 1 are replaced by the falling and rising of the lower worktable 3, respectively, and the first and second falling amounts of the upper worktable 1 are replaced by the first and second rising amounts of the lower worktable 3.

[0095] In one or more embodiments, the reference position is defined as the position where the pressure applied to the metal plate W becomes a predetermined pressure by lowering the punch Tp toward the die Td and bringing the punch Tp into contact with the metal plate W. The amount of descent when the punch Tp descends beyond the reference position is defined as the value D. When the upper worktable 1 is a fixed worktable and the lower worktable 3 is a sliding worktable, the reference position is defined as the position where the pressure applied to the metal plate W becomes a predetermined pressure by raising the die Td toward the punch Tp and bringing the die Td into contact with the metal plate W. The amount of rise when the die Td rises beyond the reference position is defined as the value D.

[0096] This application claims priority based on Japanese Patent Application No. 2024-001220, filed with the Japan Patent Office on January 9, 2024, the entire disclosure of which is incorporated herein by reference.

Claims

1. A bending machine, characterized in that, have: The upper worktable is equipped with a punch. The lower worktable is equipped with punch dies; A workbench lifting mechanism that raises or lowers the upper workbench or the lower workbench; When the metal plate is sandwiched between the punch and the die, and the upper or lower worktable is raised or lowered by the worktable lifting mechanism to bend the metal plate, the first angle sensor measures the angle of the first flange of the metal plate relative to the front side of the punch and the die, and the second angle sensor measures the angle of the second flange of the metal plate relative to the rear side of the punch and the die. as well as The control device calculates the bending angle of the metal plate based on the angles of the first flange and the second flange measured by the first angle sensor and the second angle sensor, and controls the lifting of the upper or lower worktable by the worktable lifting mechanism. After the control device controls the worktable lifting mechanism to bend the metal plate to a predetermined angle by lowering the upper worktable or raising the lower worktable, and then controls the worktable lifting mechanism to unload the load on the metal plate by raising the upper worktable by one or more stages or lowering the lower worktable by one or more stages, at the latest stage of the one or more stages and at the moment of bending the metal plate to the predetermined angle before unloading the load on the metal plate, or at the previous stage of the one or more stages, the control device determines whether the unloading of the metal plate is complete based on the amount or rate of change of the angle of the first flange measured by the first angle sensor or the angle of the second flange measured by the second angle sensor.

2. The bending machine according to claim 1, characterized in that, During the unloading process of the metal plate during a temporary bend, in which the metal plate is then bent to a predetermined temporary bend angle larger than the target bend angle, the control device determines whether the unloading of the metal plate is complete based on the amount or rate of change of the angle of the first flange or the angle of the second flange.

3. The bending machine according to claim 1 or 2, characterized in that, During the follow-up process of bending the metal plate to the target bending angle, during the final angle measurement of calculating the final bending angle of the metal plate, the control device determines whether the unloading of the metal plate is completed based on the amount or rate of change of the angle of the first flange or the angle of the second flange.

4. A control method for a bending machine, characterized in that, A control device controls a bending machine, which includes: an upper worktable on which a punch is mounted; a lower worktable on which a die is mounted; a worktable lifting mechanism for raising or lowering either the upper or lower worktable; a first angle sensor and a second angle sensor. When the metal plate is bent by raising or lowering the upper or lower worktable via the worktable lifting mechanism while the punch and die are clamping the metal plate, the first angle sensor measures the angle of the metal plate relative to the first flange on the front side of the punch and die, and the second angle sensor measures the angle of the metal plate relative to the second flange on the rear side of the punch and die. After the control device controls the worktable lifting mechanism to bend the metal plate to a predetermined angle by lowering the upper worktable or raising the lower worktable, and then controls the worktable lifting mechanism to unload the load on the metal plate by raising the upper worktable by one or more stages or lowering the lower worktable by one or more stages, at the latest stage of the one or more stages and at the moment of bending the metal plate to the predetermined angle before unloading the load on the metal plate, or at the previous stage of the one or more stages, the control device determines whether the unloading of the metal plate is complete based on the amount or rate of change of the angle of the first flange measured by the first angle sensor or the angle of the second flange measured by the second angle sensor.

5. The bending machine control method according to claim 4, characterized in that, During the unloading period, when the metal plate is bent into a predetermined temporary bending angle larger than the target bending angle, the control device determines whether the unloading of the metal plate is complete based on the amount or rate of change of the angle of the first flange or the angle of the second flange during the unloading period for calculating the springback of the metal plate bent into the temporary bending angle.

6. The bending machine control method according to claim 4 or 5, characterized in that, During the follow-up process of bending the metal plate to the target bending angle, and during the final angle measurement of calculating the final bending angle of the metal plate, the control device determines whether the unloading of the metal plate is completed based on the amount or rate of change of the angle of the first flange or the angle of the second flange.

Images