Machine tool rapid movement acceleration adjustment system and method

Abstract

A rapid traverse acceleration adjustment system for a machine tool comprises a signal measurement module, a signal judgment module, and an acceleration optimization module. The machine tool comprises a servo motor and a structural casting. The signal measurement module measures the electronic signal generated when the servo motor drives the structural casting to move linearly from a first specific position to a second specific position, or from the second specific position back to the first specific position. The signal judgment module determines whether the actual maximum current value of the motor is equal to the motor specification value based on the measured electronic signal. Based on the determination result, the acceleration optimization module calculates and adjusts the rapid traverse acceleration to an optimal value, and then determines and adjusts the smoothing time.

Description

Technical Field

[0001] The present invention relates to an acceleration adjustment method for a machine tool, and more particularly to an acceleration adjustment system and method for a machine tool in a non-machining rapid movement stroke. Background Art

[0002] The primary functional requirement for today's machine tools is the ability to perform high-speed and high-precision cutting. With the rapid development of controllers, optimizing the rapid traverse acceleration parameters of structural castings during non-machining travel can enable machine tools to meet these requirements. However, machine tool manufacturers often use foreign controllers such as FANUC, HEIDENHAIN, or SIEMENS. Machine adjusters are less familiar with controller operation and tend to approach parameter optimization conservatively. While adjusting a set of axial non-machining travel acceleration parameters can accommodate various machines, it fails to maximize machine performance and achieve optimal movement efficiency. However, setting a single rapid traverse acceleration parameter too high can cause structural vibration in the machine, which in turn can produce chatter marks on the machined surface. Therefore, determining the optimal set of axial rapid traverse acceleration parameters is a pressing issue for machine adjusters. Summary of the Invention

[0003] This invention discloses a system and method for adjusting the rapid traverse acceleration of machine tools. This method adjusts the rapid traverse acceleration of machine tools based on the machine structure vibration and the maximum motor current. Because each machine tool's parameter settings are not identical, adjusting a single set of controller parameters cannot meet the needs of all machines. Consequently, requiring adjustments for each machine tool reduces work efficiency and equipment performance. The present invention's method can replace manual adjustments and significantly improve adjustment efficiency.

[0004] In order to achieve the above-mentioned purpose, the present invention provides a machine tool rapid movement acceleration adjustment system suitable for connecting a machine tool having a servo motor and a structural casting. This system comprises a signal measurement module, a signal judgment module and an acceleration optimization module. The signal measurement module measures the electronic signal during the period when the machine tool servo motor drives the structural casting to move from a first specific position to a second specific position, or from the second specific position back to the first specific position. The signal judgment module judges whether the actual maximum current value of the servo motor is close to but not greater than the specification value of the servo motor based on the measured electronic signal. The acceleration optimization module adjusts and determines the rapid movement acceleration of the structural casting based on the judgment result, and then adjusts and determines its smoothing time.

[0005] The present invention further provides a method for adjusting the rapid movement acceleration of a machine tool, suitable for use with a machine tool having a servo motor and a structural casting. The method comprises the following steps: providing a signal measurement module to measure the electronic signal generated when the machine tool's servo motor drives the structural casting to move from a first specific position to a second specific position, or when the second specific position returns to the first specific position; providing a signal judgment module to determine, based on the measured electronic signal, whether the actual maximum current value of the servo motor is close to but not greater than the specified value of the servo motor; and providing an acceleration optimization module to adjust and determine the rapid movement acceleration of the structural casting based on the judgment result, and then further adjust and determine its smoothing time. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 Diagram showing the architecture of the machine tool's rapid traverse acceleration adjustment system.

[0007] Figure 2 Schematic diagram showing a structural casting moving back and forth between two specific positions.

[0008] Figure 3 Schematic diagram showing the change of electronic signal over time.

[0009] Figure 4 Graph showing feed rate versus actual motor current value.

[0010] Figure 5 A diagram showing the motor's factory specifications and adjusting the rapid traverse acceleration.

[0011] Figure 6 Schematic diagram showing feed rate versus position error.

[0012] Figure 7 Graph showing smoothed time versus rapid motion acceleration.

[0013] Figure 8 Flowchart showing the method for adjusting the rapid traverse acceleration of a machine tool.

[0014] Figure 9 Schematic diagram showing a before and after comparison of the system and method of the present invention. DETAILED DESCRIPTION

[0015] The machine tool rapid movement acceleration adjustment system and method of the present invention mainly discloses how to adjust the two parameters of the optimal rapid movement acceleration and smoothing time of the machine tool structural casting. The so-called optimal rapid movement acceleration refers to the maximum acceleration of the structural casting moving on a single axis without processing, and the smoothing time (curve smoothing time) refers to the time it takes for the structural casting to accelerate from a standstill to the optimal rapid movement acceleration constant, or decelerate from the optimal rapid movement acceleration constant to zero, so as to make the speed change of the structural casting smoother when moving to reduce the vibration of the machine platform. After optimization and adjustment, these two parameters will provide the user with the setting of the rapid movement stroke to fully utilize the performance of the servo motor, increase the movement speed of the structural casting to shorten the movement time, but without causing excessive position error or vibration. The so-called structural casting may be a machine platform, bed or platform in the machine tool that carries workpieces or assembles tools and has the ability to move.

[0016] Figure 1 FIG. 1 is an architecture diagram of a machine tool rapid movement acceleration adjustment system according to an embodiment of the present invention. Figure 1 As shown, a machine tool rapid traverse acceleration adjustment system 100 primarily includes a signal determination module 30 and an acceleration optimization module 40, and optionally includes a signal measurement module 20. System 100 is implemented in conjunction with a machine tool 10. Signal determination module 30 and acceleration optimization module 40 may be computers with computing, storage, and input / output capabilities.

[0017] The machine tool 10 mainly includes a controller 12, a servo loop 14, a servo motor 16, a transmission mechanism 18 and a structural casting 50, wherein the controller 12 controls the operation of the servo motor 16 through the servo loop 14, and then drives the structural casting 50 to move axially through the transmission mechanism 18. The signal measurement module 20 is connected to the machine tool 10 to obtain the current value of the servo motor 16 and all electronic signals such as the position, speed, acceleration and vibration of the structural casting 50. Therefore, the signal measurement module 20 may include devices such as ammeters, accelerometers, and optical rulers. The signal judgment module 30 receives the above signals to judge the machine structure vibration value of the machine tool 10 and the actual current value of the motor. The acceleration optimization module 40 is used to adjust the optimal rapid movement acceleration and smoothing time of the structural casting 50.

[0018] Figure 2 It is a schematic diagram of the machine tool structure casting moving linearly between the first specific position and the second specific position. Figure 2As shown, the present invention optimizes and analyzes the process by using a signal measurement module 20 to synchronously measure and collect all electronic signals during the movement of a structural casting 50 from a first specific position 52 to a second specific position 54, or from the second specific position 54 back to the first specific position 52, as the servo motor 16 drives the structural casting 50 via the drive mechanism 18. The signal measurement module 20 then collects all electronic signals during the movement, or collects all electronic signals during the return from the second specific position 54 to the first specific position 52. The distances traveled during these two periods are equal, and the signals for both round trips are substantially the same. This travel distance is called the rapid travel stroke, and no processing is performed during this travel stroke.

[0019] All electronic signals during the movement of the structural casting 50 from the first specific position 52 to the second specific position 54, such as the feed speed (V), position error (Err), rapid movement acceleration (Acc) of the structural casting 50 and the motor current (T) of the servo motor 16, are recorded in Figure 3 As shown, the position error (Err) refers to the vibration signal of the machine tool 10. When the feed speed (V) of the structural casting 50 changes, such as during deceleration or acceleration, it will cause a large amplitude vibration, which then gradually converges and slows down. The actual maximum current value of the motor is also displayed. The present invention does not limit the number of times the structural casting 50 moves back and forth between the first specific position 52 and the second specific position 54.

[0020] The signal measurement module 20 inputs the aforementioned measured electronic signals into the signal determination module 30 to determine the machine structure vibration and the maximum motor current value, thereby determining whether the actual maximum motor current value is equal to the motor's original manufacturer's specification value. This specification value refers to the motor's original manufacturer's instantaneous maximum current safety value or upper limit. However, it should be noted that in practice, it should be close to but not greater than the motor's original manufacturer's specification value for safety reasons. This applies to all of the following descriptions. Figure 4 When the motor current (T) is displayed at about 145 milliseconds, the actual maximum current value of about 70% appears at the black dot mark, that is, the servo motor 16 is operating at 70% of the original motor specification value at this time. Figure 5 The motor's factory specifications are displayed, with the horizontal axis representing motor speed (rpm) and the vertical axis representing motor torque (Nm). Once the actual maximum current value of the motor is determined, the acceleration optimization module 40 adjusts the rapid movement acceleration (Acc) of the structural casting 50 as follows.

[0021] The higher the rapid acceleration (Acc) of the structural casting 50, the greater the starting load of the servo motor 16, and the higher the actual current value (T). Conversely, the lower the actual current value (T), that is, the motor's actual current value is positively correlated with its rapid acceleration, and the rapid acceleration is positively correlated with the motor's output torque. The following examples are illustrative and not limiting:

[0022]

[0023] Among them, the initial or current stage rapid movement acceleration (Acc1), the next stage rapid movement acceleration (Acc2), the motor specification value (Tgoal), and the actual maximum current value of the motor (Tmax). Formula 1 is an example of using the ratio of the specification value of the servo motor 16 to the actual maximum current value. The current stage rapid movement acceleration is gradually adjusted according to the ratio until the torque value is equal to the torque value upper limit corresponding to the motor specification value (Tgoal). At this time, the next stage rapid movement acceleration (Acc2) will be the optimal rapid movement acceleration (Acc). Figure 5 For example, when the motor speed is 2000 rpm, the current value corresponding to the optimal rapid traverse acceleration (Acc) is recommended not to exceed the current value corresponding to the motor's maximum torque of 50 Nm. This value can be found in the motor performance table. The above determination of the optimal rapid traverse acceleration (Acc) is performed by the acceleration optimization module 40.

[0024] In addition to applying Formula 1, the present invention can also be used when the actual maximum current value (Tmax) of the motor is greater than or less than the motor specification value (Tgoal), such as Figure 5 As shown, the current stage rapid movement acceleration (Acc1) is corrected by decreasing or increasing the difference (ΔA) until the actual maximum current value (Tmax) of the motor is equal to the motor specification value (Tgoal). The next stage rapid movement acceleration (Acc2) obtained at this time is the optimal rapid movement acceleration (Acc). In other words, the adjustment made by the acceleration optimization module 40 can fully exert the maximum performance of the servo motor 16, allowing the structural casting 50 to move at the maximum acceleration without causing damage to the motor. The size of the difference (ΔA) is not limited by the present invention.

[0025] After determining the optimal rapid traverse acceleration (Acc), the next step is to determine the impact of machine vibration signals or position errors on the structural casting 50 and, consequently, the machine tool 10, while the structural casting 50 is moving at this optimal rapid traverse acceleration (Acc). Vibration signals can be obtained, for example, from a linear optical scale, motor encoder, tool tip position, or accelerometer. The signal measurement module 20 obtains a position error (Err) signal, such as the amplitude variation over time, during the movement of the structural casting 50 from a first specific position 52 to a second specific position 54. Figure 6 The display shows that when the feed rate (V) of the structural casting 50 changes, such as at the moment of deceleration and stopping (as shown by the black dot), a maximum position error (Err) of approximately 0.02 millimeters (mm) occurs. Thereafter, the amplitude gradually converges and slows down. The signal determination module 30 determines whether the position error or vibration amplitude of the machine tool 10 after stopping is equal to the user-set amplitude target or falls within the target range. This amplitude target and its convergence time can be set by the user.

[0026] Please see Figure 7 , Figure 7 A schematic diagram illustrating the adjustment of the smoothing time based on the rapid traverse acceleration is shown. The example uses the case where the feed speed (V) of the structural casting 50 is increased from zero to a constant speed, but the same applies when the feed speed is decelerated from a constant speed to zero. Once the optimal rapid traverse acceleration (Acc) of the structural casting 50 is determined, a longer smoothing time (Ts) indicates a smaller amplitude of the position error (Err), and vice versa. This indicates that the smoothing time and position error are inversely related. The following examples are provided for illustration and are not intended to be limiting:

[0027]

[0028] The initial or current smoothing time (Ts1), the next-stage smoothing time (Ts2), the actual maximum amplitude (Ampmax) of the machine, and the target amplitude (Ampgoal) of the machine are included. When the measured actual maximum amplitude (Ampmax) of the machine is equal to the target amplitude (Ampgoal), the next-stage smoothing time (Ts2) at this time is the optimal smoothing time (Ts). However, if the actual maximum amplitude (Amax) of the machine is greater than the target amplitude (Ampgoal), the next-stage smoothing time (Ts2) must be increased, thereby reducing the actual maximum amplitude (Ampmax). Otherwise, the next-stage smoothing time (Ts2) must be shortened until it is equal to the target. At this point, the acceleration optimization module 40 completes the adjustment of the smoothing time (Ts). In addition to applying Equation 2, the next-stage smoothing time (Ts2) can also be adjusted by adding or subtracting a difference (ΔT). The present invention does not limit the size of this difference (ΔT).

[0029] Figure 8 The flowchart of the present invention is a method for adjusting the rapid traverse acceleration of a machine tool. The method is suitable for connecting a machine tool 10 having a servo motor 16 and a structural casting 50, and is implemented by a machine tool rapid traverse acceleration adjustment system 100. First, a set of drive parameters for the structural casting 50, such as the rapid traverse acceleration (Acc1) and the smoothing time (Ts1), are initially set or set according to factory specifications (step S10). The structural casting 50 is then driven using these parameters to move through a rapid traverse, such as from a first specific position 52 to a second specific position 54. During this time, the signal measurement module 20 measures all electronic signals of the machine tool 10, such as motor current and machine vibration signals, (step S20).

[0030] Next, the signal determination module 30 determines whether the actual maximum current value of the servo motor 16 is equal to the factory specification value based on the measured electronic signal, as in step S30. If not, the process returns to step S40, where the acceleration optimization module 40 modifies and updates the rapid movement acceleration (Acc1) without modifying the smoothing time (Ts1). The process then returns to step S20 to move and measure again. If, after multiple modifications, the actual maximum current value of the servo motor 16 is equal to the factory specification value, the rapid movement acceleration (Acc2) at this time will be the optimal rapid movement acceleration (Acc).

[0031] Next, the signal determination module 30 determines whether the actual maximum amplitude of the machine tool 10 is equal to the target amplitude based on the measured electronic signal, as shown in step S50. If not, the process returns to step S60, and the acceleration optimization module 40 modifies and updates the smoothing time (Ts1) without modifying the rapid movement acceleration (Acc2). Then, the process returns to step S70 to move and measure again. After multiple modifications, if the smoothing time (Ts2) is equal to the target amplitude, the optimal smoothing time (Ts) is then determined. Finally, a set of optimal axial rapid movement acceleration (Acc) and its smoothing time (Ts) parameters are determined, as shown in step S80.

[0032] Figure 9 The figure shows the comparison before and after the implementation of the machine tool rapid movement acceleration adjustment system 100 and method of the present invention. Before the implementation, the structural casting 50 is driven to move the rapid movement stroke with the initial setting or the original factory setting parameters. For example, the rotation speed of the servo motor 16 is 2000 (rpm), the feed speed (V0) of the structural casting 50 is a fixed value of 24000 (mm / min), the initial rapid movement acceleration (Acc0) is equal to 2857 (mm / sec / sec) and the smoothing time (Ts0) is equal to 140 milliseconds (ms). The change of the initial rapid movement optimal speed (Acc0) presents an isosceles triangle. At this time, the maximum current value (T) of the motor is about 56 (%), and the motor torque is 38 (Nm). Figure 5 The original motor specifications show a torque cap of 50 (Nm) in intermittent operation mode, with a difference of 12 (Nm). After checking that the position error (Err) meets the convergence time and amplitude targets, this indicates that the initial rapid movement acceleration (Acc0) and smoothing time (Ts0) are too conservative and should be adjusted and optimized.

[0033] Figure 9Furthermore, it is shown that, at the same motor speed and feed rate, after implementing the system and method of the present invention, at the same feed rate (V), the rapid movement acceleration (Acc) can be increased to 3279 (mm / sec / sec) and the smoothing time (Ts) can be shortened to 26 (ms). The change in rapid movement acceleration (Acc) is presented in an isosceles trapezoidal shape. At this time, the maximum motor current value (T) is approximately 73 (%), and the motor torque is approximately 49 (Nm), only 1 (Nm) away from the motor upper limit. After checking that the position error (Err) meets the convergence time and amplitude targets, the adjustment result can improve the movement efficiency by approximately 47% compared to the original factory settings.

[0034] In summary, the adjustment system and method of the present invention utilizes a servo motor to drive a transmission mechanism, which in turn drives the structural casting back and forth between two specific positions. A signal measurement module collects electronic signals during each movement. A signal determination module automatically interprets the electronic signals to determine the machine's actual maximum amplitude and the motor's actual maximum current. Based on these results, an acceleration optimization module adjusts the optimal rapid traverse acceleration and smoothing time, optimizing the machine tool's axial non-machining travel performance while meeting target amplitude requirements. Therefore, the present invention meets the requirements for an invention patent.

[0035]

Explanation of symbols

[0036] 100: Machine tool rapid movement acceleration adjustment system

[0037] 10: Machine tools

[0038] 12: Controller

[0039] 14: Servo loop

[0040] 16: Servo motor

[0041] 18: Transmission mechanism

[0042] 20: Signal measurement module

[0043] 30: Signal judgment module

[0044] 40: Acceleration optimization module

[0045] 50: Structural castings

[0046] 52: First specific position

[0047] 54: Second specific position

[0048] S10-S80: Steps

Claims

1. A machine tool rapid movement acceleration adjustment system, suitable for connecting a machine tool having a servo motor and a structural casting, the system comprising: a signal measurement module configured to measure a plurality of electronic signals generated when the servo motor of the machine tool drives the structural casting to move from a first specific position to a second specific position, or when the servo motor of the machine tool returns to the first specific position; the plurality of electronic signals also including at least a vibration signal of the machine tool when the structural casting stops; a signal determination module for determining, based on the plurality of electronic signals measured, whether the actual maximum current value of the servo motor is equal to the specification value of the servo motor; as well as an acceleration optimization module, for adjusting and determining the rapid movement acceleration of the structural casting according to the judgment result; When the actual maximum current value is not equal to the specification value, the acceleration optimization module is configured to modify and update the rapid movement acceleration without modifying a smoothing time, wherein the smoothing time is the time from when the rapid movement acceleration decelerates to zero; The signal determination module is further configured to determine a maximum position error of the structural casting from the position error signal of the structural casting captured by the signal measurement module, and further derive a temporal variation in the amplitude of the position error of the structural casting to determine whether an actual maximum amplitude generated by the structural casting is equal to a target amplitude. When the actual maximum amplitude is greater than the target amplitude, the acceleration optimization module is configured to increase the smoothing time; When the actual maximum amplitude is smaller than the amplitude target, the acceleration optimization module is configured to shorten the smoothing time until the amplitude target is achieved; The acceleration optimization module is used to adjust and determine the rapid movement acceleration and the smoothing time of the rapid movement acceleration when the actual maximum amplitude of the machine is equal to the amplitude target.

2. A method for adjusting the acceleration of a machine tool rapid movement, suitable for a machine tool connected to a servo motor and a structural casting, the method comprising the following steps: a signal measurement module for measuring a plurality of electronic signals generated when the servo motor of the machine tool drives the structural casting to move from a first specific position to a second specific position, or when the servo motor of the machine tool returns to the first specific position; the plurality of electronic signals also including at least a vibration signal of the machine tool when the structural casting stops; A signal determination module is used to determine whether an actual maximum current value of the servo motor is equal to a specified value of the servo motor based on the plurality of electronic signals measured; Modifying and updating the rapid movement acceleration using the acceleration optimization module when the actual maximum current value is not equal to the specification value without modifying a smoothing time, wherein the smoothing time is the time from when the rapid movement acceleration decelerates to zero; The signal determination module further determines a maximum position error of the structural casting from the position error signal of the structural casting captured by the signal measurement module, and further deduces how the amplitude of the position error of the structural casting changes over time to determine whether the actual maximum amplitude generated by the structural casting is equal to the target amplitude; increasing the smoothing time by the acceleration optimization module when the actual maximum amplitude is greater than the amplitude target; shortening the smoothing time by the acceleration optimization module when the actual maximum amplitude is less than the amplitude target until the amplitude target is achieved; The acceleration optimization module is used to adjust and determine the rapid movement acceleration and the smoothing time of the rapid movement acceleration when the actual maximum amplitude of the machine is equal to the amplitude target.

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