A method for coupling error protection and compensation

Abstract

The present invention discloses a method for coupling error protection and compensation. The method comprises the following steps: 1) setting a threshold value, coupling the axial driving axis and the driven axis to start motion processing; 2) when the error between the driving axis and the driven axis is greater than the set threshold value, an alarm is issued and processing is stopped; 3) checking the synchronization error between the driving axis and the driven axis, and when the synchronization error is greater than the set threshold value, the coupling diagnosis mode is turned on; 4) moving the driving axis in the coupling diagnosis mode, performing synchronization error elimination, and then checking the synchronization error; 5) when the synchronization error is greater than the set threshold value, jumping to step 4) until the synchronization error is less than the set threshold value; 6) turning off the coupling diagnosis mode and continuing processing. A method for coupling error protection and compensation in the present invention can protect and eliminate the error of the axial coupling motion of the machine tool, can limit the position error of the coupling axis, ensure the efficiency of processing, and reduce safety hazards.

Description

Technical Field

[0001] The invention relates to the field of numerical control machining, and in particular to a method for coupling error protection and compensation. Background Art

[0002] In CNC machining, in order to meet the processing requirements of different machine tools, machines tend to develop in the direction of large-scale and complex, and often involve the situation of two axial coupling and simultaneous motion processing. At present, the coupling methods generally include master-slave coupling, mechanism coupling and load-bearing coupling, etc. The purpose of coupling is to make the two axes move simultaneously in a certain proportion.

[0003] However, due to servo lag problems such as mechanisms or motors, the two axial movement distances are often different (similar to forward and backward movement), which leads to deformation of the mechanism and errors in the processed workpiece. Simple coupling motion cannot guarantee the accuracy of the movement distance, and it is also impossible to protect the mechanism and eliminate errors. If the coupling error continues to accumulate, the load rate of the motor movement process will soar, and the movement cannot be synchronized, resulting in deformation of the mechanism, motor stalling, and even motor damage, which will not only affect the efficiency of processing and production, but also cause safety hazards. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method for coupling error protection and compensation.

[0005] According to one aspect of the present invention, a method for coupling error protection and compensation is provided, comprising the following steps:

[0006] 1) Set a threshold value to couple the axial driving axis and the driven axis to start motion processing;

[0007] 2) When the error between the driving axis and the driven axis is greater than the set threshold, an alarm is issued and processing is stopped;

[0008] 3) Check the synchronization error between the active shaft and the driven shaft. When the synchronization error is greater than the set threshold, start the coupling diagnosis mode;

[0009] 4) Move the active axis in the coupling diagnosis mode, perform synchronization error elimination, and then check the synchronization error;

[0010] 5) When the synchronization error is greater than the set threshold, jump to step 4) until the synchronization error is less than the set threshold;

[0011] 6) Turn off the coupling diagnostic mode and continue processing:

[0012] The method for performing synchronization error elimination includes the following steps:

[0013] a) Start the origin search mode and enable the active axis and the driven axis to move together;

[0014] b) When the driven axis returns to the origin, the active axis moves simultaneously and the origin offset is set;

[0015] c) When the active axis returns to the origin, the driven axis moves simultaneously;

[0016] d) Determine through the PLC axis that the position coordinate difference between the active axis and the driven axis encoder is within a reasonable range;

[0017] e) Turn off the coupling and synchronization, use the PLC axis to control the driven axis and execute the PLC axis to return to the origin;

[0018] f) Turn on coupling and synchronization, and proceed with processing if origin search is completed, otherwise jump to step a).

[0019] A method for coupling error protection and compensation in the present invention protects and eliminates the error of the axial coupling motion of the machine tool by coupling the axial direction to follow the origin and re-calibrating after emergency stop. It can limit the position error of the coupling axis, and when the position difference between the active axis and the driven axis is greater than a specified value, there will be an early warning to prevent the coupling error from accumulating. This not only ensures the processing efficiency, but also reduces safety hazards.

[0020] In some embodiments, in step 1), the driving shaft and the driven shaft are coupled in a 1:1 pair. This is beneficial in that it describes the coupling of the driving shaft and the driven shaft.

[0021] In some embodiments, in step 3), when the synchronization error is not greater than a set threshold, the alarm is reset and the processing is continued. This is beneficial in that the processing can be continued when the error does not affect the processing.

[0022] In some embodiments, in step 3), the active shaft is moved by setting a hand wheel or inch motion. The benefit is that a specific method of moving the active shaft is described.

[0023] In some implementations, in step b) and step c), if the origin search fails, the process jumps to step a). The benefit is that, in the above steps, if the origin search fails, synchronization error elimination can be performed again.

[0024] In some embodiments, in step d), the position coordinate difference between the active shaft and the driven shaft encoders is the difference between the driven shaft encoder feedback and the active shaft encoder feedback. The invention is beneficial in that it describes a method for calculating the position coordinate difference between the active shaft and the driven shaft encoders.

[0025] In some embodiments, the following steps are also included: 7) emergency stop is initiated, the driving axis and the driven axis are stopped, and error correction is performed after the emergency stop is canceled. The benefit is that the processing can be stopped at any time when needed through the emergency stop function.

[0026] In some embodiments, in step 7), after the emergency stop is cancelled, it is determined whether there is an error between the driving shaft and the driven shaft, and if there is an error, the correction mode is entered. The advantage is that the error can be corrected through the correction mode after the emergency stop is cancelled.

[0027] In some embodiments, after entering the correction mode, the error amount is automatically calculated and it is determined whether it exceeds a set threshold. If it exceeds the set threshold, manual correction is performed. The benefit is that a case of the correction mode is described.

[0028] In some embodiments, if the error amount does not exceed a set threshold, the active axis and the driven axis are decoupled, the driven axis is started, the driven axis is triggered to perform a correction action in the PLC axis mode, and the PLC axis moves to compensate for the overflowed deviation amount. It is beneficial that another case of the correction mode is described. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flowchart of a method for coupling error protection and compensation according to an embodiment of the present invention;

[0030] Figure 2 for Figure 1 A flow chart of a synchronization error elimination method for coupling error protection and compensation is shown;

[0031] Figure 3 for Figure 2 Schematic diagram of the synchronization error elimination method shown. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0033] Figure 1 The flowchart of a method for coupling error protection and compensation according to an embodiment of the present invention is schematically shown. Figure 2 Shows Figure 1 The process of the synchronous error elimination method for coupling error protection and compensation method in Figure 3 Shows Figure 2 The structure of the synchronization error elimination method in FIG. Figure 1-3As shown, this method is used to eliminate the error between the axes during the axial movement of the CNC machining machine to ensure smooth machining. Among them, the CNC machining is controlled by the PLC axis, and the machine has two coupled axes, namely the active axis (set as the A axis) and the driven axis (set as the a axis). That is, when the A axis moves, the a axis will be installed with a set ratio to follow the synchronous movement. For example, the A axis and the a axis can be 1:1 coupled, that is, they move at the same speed, and the two axes will inevitably produce errors during movement.

[0034] The main operation process of this method is described as follows.

[0035] First, an error threshold is set in the system, and then the A-axis and the a-axis start axial movement for processing. When the error between the two axes is greater than the set threshold, the system issues an alarm and stops processing. Then, the synchronization error between the A-axis and the a-axis is checked. If the synchronization error is less than the set threshold, the alarm is reset and processing continues; if the synchronization error is greater than the set threshold, the system turns on the coupling diagnosis mode.

[0036] In the diagnostic mode, the A-axis can be moved by handwheel or jog to eliminate the synchronization error, and then the synchronization error can be rechecked. If the synchronization error is still greater than the set threshold, the system will issue an alarm and reissue the command to continue moving the A-axis to eliminate the synchronization error until the synchronization error is less than the set threshold.

[0037] Finally, turn off the coupling diagnostic mode and continue processing.

[0038] like Figure 2 As shown, the above method for performing synchronization error elimination includes multiple steps, which are mainly described as follows.

[0039] The first step is to start the preset origin search mode and enable the A-axis and a-axis to move together;

[0040] The second step is to execute the A-axis back to the origin (i.e. the motor origin). In the process of returning to the origin, the A-axis will also move with it and set the origin offset. Figure 3 As shown, the arrow is the processing direction, point A is the origin of the a-axis motor, point B is the origin position of the a-axis in the ideal state, and the origin offset is the displacement from point C to point B, which is used to correct the position of the origin.

[0041] The third step is to execute the A-axis back to origin (and its mechanical origin), and the A-axis will also move in the process of returning to origin. Figure 3 As shown, point D is the mechanical origin of the A-axis.

[0042] In addition, in the second and third steps, if the origin search fails, jump to the first step to re-eliminate the synchronization error.

[0043] The fourth step is to determine through the PLC axis that the position coordinate difference between the A-axis and a-axis encoders is within a reasonable range, where the position coordinate difference S between the A-axis and a-axis encoders is the difference in encoder feedback between the two axes, that is, S = a-axis encoder feedback - difference in A encoder feedback.

[0044] Step 5. Turn off the coupling synchronization, use the PLC axis to control the a-axis, and execute the PLC axis to return to its mechanical origin.

[0045] The sixth step is to turn on the coupling and synchronization. If the origin search is completed, proceed with the processing. Otherwise, jump to the first step to eliminate the synchronization error again.

[0046] In addition, when the machine is processing, if an emergency stop is required, the emergency stop button can be pressed to start the emergency stop. At this time, the system will stop the A-axis and the a-axis from processing. However, due to factors such as inertia and mechanism assembly, the coupled axes often cause differences in the axial position of the A-axis. Even if the emergency stop is started in a stationary state, the positions of the two axes will change to a certain extent due to the stress of the machine. Therefore, error correction is also required after the emergency stop is canceled.

[0047] After the emergency stop is canceled, it is first determined whether there is an error between the A-axis and the a-axis. If there is an error, the preset correction mode is entered. In the correction mode, the system automatically calculates the error and determines whether it exceeds the set threshold. If the error exceeds the set threshold, manual correction is performed by handwheel or inch movement.

[0048] If the error amount does not exceed the set threshold, the coupling between the A-axis and the A-axis is released, and the A-axis is started at the same time, triggering the A-axis to perform a correction action in the PLC axis mode, and the PLC axis can move to compensate for the overflow deviation.

[0049] Finally, after the compensation is completed, the correction mode is automatically exited, and the A-axis and the A-axis are coupled again to complete the correction.

[0050] In summary, the method for coupling error protection and compensation in the present invention has the following outstanding innovations compared with the prior art:

[0051] 1. It has the error protection function for the axial coupling motion of the machine tool, and there will be an early warning when the error is greater than the set threshold, and the threshold can be adaptively adjusted;

[0052] 2. It has coupling diagnosis function, which can determine (including manual adjustment) the coupling error range, as well as perform calibration and adjustment of operation actions;

[0053] 3. When errors occur, the coupling errors can be eliminated by tracing the origin, including measuring and setting the offset of the driven axis origin, thereby checking the two axial movement error values, etc., to prevent the accumulation of coupling errors;

[0054] 4. During processing, pressing the emergency stop button will automatically decelerate the axis to zero. Due to axial friction and assembly problems, the axial mechanical coordinates will change, resulting in inaccurate position. This method can automatically correct the emergency stop.

[0055] 5. This method also has the function of correcting human errors caused by mechanism combination and assembly, which not only further ensures the processing efficiency but also reduces safety hazards.

[0056] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for coupling error protection and compensation, characterized in that: The following steps are included 1) Set a threshold value to couple the axial driving axis and the driven axis to start motion processing; 2) When the error between the driving axis and the driven axis is greater than the set threshold, an alarm is issued and processing is stopped; 3) Check the synchronization error between the active shaft and the driven shaft. When the synchronization error is greater than the set threshold, start the coupling diagnosis mode; 4) Move the active axis in the coupling diagnosis mode, perform synchronization error elimination, and then check the synchronization error; 5) When the synchronization error is greater than the set threshold, jump to step 4) until the synchronization error is less than the set threshold; 6) Turn off the coupling diagnosis mode and continue processing; 7) When an emergency stop is required, the emergency stop is initiated, the driving axis and the driven axis stop, and after the emergency stop is canceled, it is determined whether there is an error between the driving axis and the driven axis. If there is an error, the correction mode is entered to correct the error; The method for performing synchronization error elimination includes the following steps: a) Start the origin search mode and enable the active axis and the driven axis to move together; b) When the driven axis returns to the origin, the active axis moves simultaneously and the origin offset is set; c) executing the active axis to return to the origin, the driven axis moves simultaneously, and in step b) and step c), if the origin search fails, jump to step a); d) Determine through the PLC axis that the position coordinate difference between the active axis and the driven axis encoder is within a reasonable range, and the position coordinate difference between the active axis and the driven axis encoder is the difference between the feedback of the driven axis encoder and the feedback of the active axis encoder; e) Turn off the coupling and synchronization, use the PLC axis to control the driven axis and execute the PLC axis to return to the origin; f) Turn on coupling and synchronization, and proceed with processing if origin search is completed, otherwise jump to step a).

2. A method for coupling error protection and compensation according to claim 1, characterized in that: In step 1), the driving shaft and the driven shaft are coupled in a 1:1 pair.

3. The method for coupling error protection and compensation according to claim 1, characterized in that: In step 3), when the synchronization error is not greater than the set threshold, the alarm is reset and processing continues.

4. The method for coupling error protection and compensation according to claim 1, characterized in that: In step 3), the active axis is moved by setting the handwheel or jogging.

5. The method for coupling error protection and compensation according to claim 1, characterized in that: After entering the correction mode, the error amount is automatically calculated and it is determined whether it exceeds the set threshold. If it exceeds the set threshold, manual correction is performed.

6. The method for coupling error protection and compensation according to claim 5, characterized in that: If the error amount does not exceed the set threshold, the coupling between the active axis and the driven axis is released, the driven axis is started, the driven axis is triggered to perform correction action in the PLC axis mode, and the PLC axis moves to compensate for the overflow deviation.

Images