Groove square tube cutting follow-up and linear axis compensation method

Abstract

The application discloses a kind of bevel square tube cutting follow-up and linear axis compensation method, belong to bevel square tube cutting technical field, including the following steps: before cutting, first do capacitance correction processing;During cutting, Z-axis control mainly reference NC position command, simultaneously through Z-axis temperature rise compensation circuit real-time monitoring the working temperature of capacitance, realize the compensation to the performance change caused by temperature rise of capacitance, and then carry out height error compensation on the basis of NC position command;Judge whether h is equal to set value h0, if not, then cutting position exists error, Z-axis follows measured actual height h and does PID closed loop control;In the processing situation of bevel cutting, in the case that there is angle in swing head shaft, if Z-axis follow-up is started simultaneously, Y-axis position compensation is started simultaneously.The application is mainly NC, and capacitance value feedback is auxiliary, to ensure that cutting path meets expectation.The application can compensate the problem of focal point position deviation caused by swing head swing, and the machining precision is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of groove square tube cutting, in particular to a follow-up and linear shaft compensation method for groove square tube cutting. BACKGROUND

[0002] When laser groove cutting square tubes, it is necessary to ensure the consistency of the processing path, so that the workpiece cut out at the cross section will be flush, which greatly helps the subsequent welding work.

[0003] In the process of groove cutting, it is difficult to accurately control the key parameters such as the angle, width and depth of the groove by traditional methods. For example, mechanical cutting is easily affected by tool wear and machine precision limitations; heat cutting is affected by airflow and heat source stability, resulting in large groove size deviation. When the cutting head swings, the focal point position will deviate, resulting in inconsistent cutting paths before and after the cutting head swings, and poor consistency of the cutting path.

[0004] Therefore, the present application designs a follow-up and linear shaft compensation method for groove square tube cutting to solve the above problems. SUMMARY

[0005] In view of the above shortcomings of the prior art, the present application provides a follow-up and linear shaft compensation method for groove square tube cutting.

[0006] To achieve the above purpose, the present application realizes the following technical solutions:

[0007] A follow-up and linear shaft compensation method for groove square tube cutting, comprising the following steps:

[0008] Step one, before cutting, first do the capacitance correction processing; during cutting, real-time monitor the capacitance value, and deduce the distance h between the nozzle and the metal plate in actual processing;

[0009] Step two, during cutting, Z-axis control mainly refers to the position command of NC, and at the same time, real-time monitor the working temperature of the capacitance through the Z-axis temperature rise compensation circuit, realize the compensation of the performance change of the capacitance due to temperature rise, and then compensate the height error on the basis of the position command of NC;

[0010] Step three, judge whether h is equal to the set value h0, if yes, there is no error in the cutting position, if not, there is an error in the cutting position, and the Z-axis follows the actual height h measured at the moment to do PID closed loop control;

[0011] Step four, in the processing situation of bevel cutting, if the Y-axis position compensation is started at the same time under the condition that the head shaft has an angle, the Z-axis follow-up is started at the same time.

[0012] Further, in step one, before cutting, the height between the nozzle and the metal plate is different, and the generated capacitance value is different, according to the capacitance value being 0 when the plate surface is attached, and gradually recording the capacitance value at different heights, a height-capacitance value table is generated.

[0013] Further, in step one, during cutting, the capacitance value is monitored in real time, and according to the current capacitance value and the height-capacitance value table, the distance h between the nozzle and the metal plate in actual processing is inferred.

[0014] Further, in step two, the Z-axis temperature rise compensation circuit includes a feedback circuit composed of an operational amplifier, a thermistor and the like.

[0015] Further, the thermistor is used as a temperature sensor, and the resistance value change is converted into an electrical signal to feed back to the operational amplifier, and the operational amplifier outputs a corresponding control signal to adjust the voltage applied to the capacitor or the current flowing through the capacitor according to the set reference signal.

[0016] Further, in step three, the Z-axis follows the measured actual height h at the moment to do PID closed loop control, realizes h=h0, and realizes position compensation.

[0017] Further, in step four, the position compensation command of the Y-axis=(Z-axis mechanical coordinate command-Z-axis motor feedback)*tan(A-axis absolute coordinate command).

[0018] Further, in step four, the Z-axis and A-axis commands adopt a speed feedforward compensation strategy to compensate for servo lag and communication delay.

[0019] Compared with the prior art, the present application has the beneficial effects that: the present application mainly uses NC (Numerical Control) and capacitance value feedback as auxiliary, to ensure that the cutting path meets the expectations. The servo and Y-axis compensation strategy provided by the present application can compensate for the problem of focal point position deviation caused by the swing head swinging, and ensure that the focal point position of the cutting head is always at the same position of the pipe under the condition of arbitrary swinging of the swing head, thereby ensuring the consistency of the machining path and improving the machining precision. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creating any creative labor.

[0021] Figure 1The principle diagram of a slope groove square tube cutting follow-up and linear shaft compensation method. DETAILED DESCRIPTION

[0022] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0023] Embodiment one: in some embodiments, referring to the drawings of the specification Figure 1 A slope groove square tube cutting follow-up and linear shaft compensation method comprises the following steps:

[0024] Step one: before cutting, first do the capacitance correction processing; during cutting, monitor the capacitance value in real time, and deduce the distance h between the nozzle and the metal plate in actual processing;

[0025] During cutting, the Z-axis control mainly refers to the position command of NC (Numerical Control), and the target is to make the original NC command basically conform to the size and shape of the workpiece. If the workpiece itself is deformed and the size deviates, the nozzle may collide with the workpiece or the laser focal depth error may affect the processing under the condition of only referring to the NC. Therefore, the Z-axis refers to the capacitance value to make corresponding position compensation to avoid the above situations.

[0026] The specific steps of step one are as follows:

[0027] Step 1.1: before cutting, first do the capacitance correction processing. Specifically, because the height between the nozzle and the metal plate is not the same, the capacitance value produced is not the same. According to the fact that the capacitance value is 0 when it is attached to the surface of the plate, and gradually away from the metal plate, the capacitance value at different heights is recorded to generate a height-capacitance value relationship table;

[0028] Step 1.2: during cutting, monitor the capacitance value in real time, and according to the current capacitance value and the height-capacitance value relationship table, deduce the distance h between the nozzle and the metal plate in actual processing;

[0029] Step two: during cutting, the Z-axis control mainly refers to the position command of NC, and simultaneously monitors the working temperature of the capacitance through the Z-axis temperature rise compensation circuit to realize the compensation of the performance change of the capacitance caused by temperature rise, and then compensate the height error on the basis of the position command of NC;

[0030] Specifically, at the same height from the plate surface, the capacitance value will change due to temperature changes. The Z-axis temperature rise compensation circuit includes a feedback circuit composed of an operational amplifier, a thermistor, etc. The thermistor is used as a temperature sensor, and its resistance change is converted into an electrical signal and fed back to the operational amplifier. The operational amplifier outputs a corresponding control signal based on a set reference signal to adjust the voltage applied to the capacitor or the current flowing through the capacitor, thereby compensating for the performance change of the capacitor caused by temperature rise.

[0031] Step 3: Determine whether h is equal to the set value h0. If so, there is no error in the cutting position. If not, there is an error in the cutting position. The Z axis follows the measured actual height h to perform PID closed-loop control to achieve h=h0 and realize position compensation.

[0032] Step 4: Please refer to Figure 1 In the case of bevel cutting, if the swing axis (A axis) has an angle (for example -45°), if the Z axis is turned on at the same time, it will cause the laser cutting position to be wrong (A axis). NC It is the position of the laser under the processing file. Laser This is the actual position of the laser without the groove strategy), then the Y axis also needs to make a certain position compensation;

[0033] Y-axis position compensation command = (Z-axis mechanical coordinate command - Z-axis motor feedback) * tan (A-axis absolute coordinate command);

[0034] Among them, the Z-axis and A-axis commands need to take into account servo lag and communication delay, and are implemented through a speed feedforward compensation strategy to ensure that they match the timing of motor feedback.

[0035] This invention utilizes numerical control (NC) as the primary control method, supplemented by capacitance feedback. This is because when machining non-planar workpieces with significant curvature variations (such as the rounded corners of square tubes), the height of the capacitance feedback is unreliable and unpredictable. Using capacitance height as the primary control method for tracking will result in unstable tracking and height errors. The laser beveling process for square tubes is affected by the geometry of the tube and nozzle, so the reliability of the capacitance value requires a tracking strategy that accounts for these factors, in addition to numerical control, to ensure the cutting path meets expectations.

[0036] The servo and Y-axis compensation strategy provided by the present application can compensate for the problem of focal point position deviation caused by the swing of the swing head, and ensure that the focal point position of the cutting head is always at the same position of the pipe under the condition of arbitrary swing of the swing head, thereby ensuring the consistency of the machining path and improving the machining precision. Precise bevel machining ensures good matching of the welded joint, reduces the generation of welding defects (such as incomplete penetration, slag inclusion, porosity, etc.), and makes the mechanical properties such as strength and toughness of the welded joint closer to the base material, thereby significantly improving the overall quality and reliability of the welded structure. For example, in the field of aerospace, the welded parts after high-precision laser bevel compensation machining can better withstand stress and load under extreme environment, thereby ensuring flight safety.

[0037] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements will not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for servo and linear axis compensation for beveled square tube truncation, characterized by: The following steps are involved: Step 1: Before cutting, perform capacitance calibration. During cutting, monitor the capacitance value in real time and infer the distance h between the nozzle and the metal sheet during actual processing. Step 2: During the cutting process, the Z-axis control refers to the position command of the NC. At the same time, the Z-axis temperature rise compensation circuit monitors the working temperature of the capacitor in real time to compensate for the performance change of the capacitor due to temperature rise, and then compensates for the height error based on the position command of the NC. Step 3: Determine whether h is equal to the set value h0. If so, there is no error in the cutting position. If not, there is an error in the cutting position. The Z axis follows the measured actual height h to perform PID closed-loop control. Step 4: In the case of bevel cutting, when the swing axis is at an angle, if the Z-axis is turned on at the same time, the Y-axis will also start position compensation; In step 1, before cutting, the capacitance values ​​generated vary due to the different heights between the nozzle and the metal sheet. The capacitance value is zero when the nozzle is in contact with the sheet surface, and gradually moves away from the metal sheet. The capacitance values ​​at different heights are recorded to generate a height-capacitance relationship table. In step 2, the Z-axis temperature rise compensation circuit includes a feedback circuit composed of an operational amplifier and a thermistor; In step 3, the Z axis follows the measured actual height h and performs PID closed-loop control to achieve h=h0, thus achieving position compensation. In step 4, the Y-axis position compensation command = (Z-axis mechanical coordinate command - Z-axis motor feedback) * tan (A-axis absolute coordinate command).

2. The method for servo and linear axis compensation of grooved square tube truncation according to claim 1, characterized in that: In step 1, while cutting is in progress, the capacitance value is monitored in real time, and the distance h between the nozzle and the metal sheet during actual processing is inferred based on the current capacitance value and the height-capacitance value relationship table.

3. The method for servo and linear axis compensation for beveled square tube truncation according to claim 1, characterized in that: A thermistor is used as a temperature sensor, and its resistance change is converted into an electrical signal and fed back to the operational amplifier. The operational amplifier outputs a corresponding control signal based on the set reference signal to adjust the voltage applied to the capacitor or the current flowing through the capacitor.

4. The method for servo and linear axis compensation for beveled square tube truncation according to claim 1, characterized in that: In step 4, the Z-axis and A-axis commands use a velocity feedforward compensation strategy to compensate for servo lag and communication delay.

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