A method for spindle thermal elongation variation detection and compensation

Abstract

A kind of spindle thermal elongation change detection and compensation method, comprising the following steps: 1) spindle tool length is detected in cold state, and is recorded as l 0 2) before using spindle thermal elongation change compensation, it needs to be carried out first spindle thermal equilibrium calibration;Spindle warm-up change law calibration is carried out by "spindle thermal equilibrium calibration program", and compensation function parameter value is obtained;Spindle thermal elongation change law calibration must be carried out before use;3) after machining is completed, whether the thermal elongation compensation of spindle is judged according to the measurement length.The detection efficiency and result accuracy of in-machine measurement are improved in the present application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of measurement and compensation, and particularly relates to a method for detecting and compensating thermal elongation change of a main shaft. BACKGROUND

[0002] Thermal elongation change of a main shaft is an inevitable application problem in numerical control machining. With the continuous application of in-machine measurement technology in numerical control machining, the influence of thermal elongation change of the main shaft needs to be accurately detected and compensated to ensure the authenticity of measurement data and guide accurate, stable and efficient numerical control machining application.

[0003] In-machine measurement application is often frequently alternated with machining process. In the machining process, the machine tool parts heat up due to the rotation of the main shaft and the movement of the machine tool, and the temperature of the main shaft changes obviously. The temperature of the main shaft gradually rises at the beginning of machining and finally tends to be stable with the passage of time. In the measurement process, the main shaft stops rotating, the chiller continues to work, and the temperature of the main shaft begins to drop and gradually tends to be stable. Therefore, the temperature of the main shaft changes constantly in machining and measurement, and the elongation of the main shaft caused by the change of the temperature of the main shaft has a certain influence on the machining quality and measurement data.

[0004] At present, the machine tool is warmed up before use. In machining, the main shaft temperature can be stabilized by warming up to obtain a good machine tool state. In the measurement process, the machine tool state cannot be stabilized by warming up, the warming up time is long, and the machining efficiency is affected. The in-machine measurement working condition is mostly after machining, the main shaft of the machine tool is in the rapid change stage of cooling, and the working condition is complex and difficult to use warming up. SUMMARY

[0005] The purpose of the present application is to provide a method for detecting and compensating thermal elongation change of a main shaft to solve the above problems.

[0006] To achieve the above purpose, the present application adopts the following technical scheme:

[0007] A method for detecting and compensating thermal elongation change of a main shaft, comprising the following steps:

[0008] 1) Detect the main shaft tool length in the cold state, denoted as l0;

[0009] 2) Before using the compensation of thermal elongation change of the main shaft, the thermal equilibrium calibration of the main shaft needs to be performed first. The thermal elongation change law of the main shaft is calibrated through a "main shaft thermal equilibrium calibration program" to obtain the compensation function parameter value. The thermal elongation change law of the main shaft must be calibrated before use.

[0010] 3) After machining is completed, it is judged whether to perform thermal elongation compensation of the main shaft according to the measurement time. According to experimental experience, the following general law is obtained:

[0011] ① Measurement time is within 5 minutes, no compensation (the spindle elongation changes within 2 μm);

[0012] Measurement starts, first detects the tool length of the measuring head, and saves the current tool length as l1, then executes the measurement program, and completes the measurement;

[0013] ② Measurement time is more than 5 minutes, compensation is required (the spindle elongation changes more than 2 μm);

[0014] Measurement first detects the tool length of the measuring head, and saves the current tool length as l1, then executes the measurement program, and completes the measurement, and then detects the tool length of the measuring head again, and saves the current tool length as l ’ 1; manually export the measurement data and the corresponding measurement time, save it as a TXT document in a specified form; run the "thermal compensation program", open the measurement data document according to the prompt and confirm, complete the compensation and save; ③ Measurement is performed after cooling for 30 minutes, no compensation is required;

[0015] Measurement starts, first detects the tool length of the measuring head, and saves the current tool length as l1, then executes the measurement program, and completes the measurement.

[0016] The application also has the following additional technical features:

[0017] As a further specific optimization of the technical solution of the application: the "spindle thermal balance calibration program" is a special calibration macro program, and its main purpose is to obtain the parameter value of the compensation function, and the main logic of the program is:

[0018] 001, the program starts;

[0019] 002, detect the tool length l0;

[0020] 003, the spindle starts at a warm-up speed, and the tool length l i is continuously detected;

[0021] 004, judge whether the stable warm-up reaches the stable state, the judgment method is: continuously detect the tool length for 5 times, the error of adjacent two times is not more than 0.2 μm, and the total error of 5 times is not more than 0.3 μm;

[0022] 005, the maximum calibration time is not more than 60 minutes, if it has not reached the stable state at 60 minutes, record the tool length l ’ ∞ , and a pop-up window alarm is prompted;

[0023] 006, the program ends.

[0024] As a further specific optimization of the technical solution of the application: the "compensation function" is a regular change function of the spindle thermal elongation characteristic, and the formula and parameter calculation formula are as follows:

[0025] L = a · e (b·t) + c (1),

[0026] Wherein: a is the thermal elongation coefficient; a = l0- l ∞ , l ∞ Take the equilibrium state tool length, l0take the tool length before measurement;

[0027] b is the thermal elongation time coefficient; b = ln((l i - l ∞ ) / (l0- l ∞ )) / Δt, Δt = t i - t0; calibration, take 30 min tool length to calculate b parameter value;

[0028] c is the equilibrium state tool length; c = l ∞ .

[0029] As the technical scheme of the application is further optimized: the "measurement program" is output by the program writing software or handwritten for the NC program of workpiece features, size, allowance measurement; the measurement time of the data recorded in the measurement.

[0030] As the technical scheme of the application is further optimized: the "thermal equilibrium compensation program" is a special macro program for compensating the measurement data. The compensation method is to determine the "compensation function" according to formula (1), calculate the corresponding thermal elongation compensation value under different measurement time, and add the compensation value to the original measurement value to complete the compensation.

[0031] As the technical scheme of the application is further optimized: the tool length detector is used to continuously measure the spindle tool length, and the continuous change rule of the spindle thermal elongation is obtained; the measurement results of the measurement points in the machine measurement are compensated according to the change rule of the spindle thermal elongation, and more accurate measurement results are obtained.

[0032] As the technical scheme of the application is further optimized: mainly for the change rule of the spindle thermal elongation after machining.

[0033] As the technical scheme of the application is further optimized: the detection and compensation method is also applicable to the research of the change rule of the spindle thermal elongation under other working conditions.

[0034] As the technical scheme of the application is further optimized: the change rule of the spindle thermal elongation after machining is studied, and the purpose is to compensate the influence of the change amount of the spindle thermal elongation on the measurement results in the application process of in-machine measurement.

[0035] As the further specific optimization of the technical scheme of the application, the tool length detection instrument adopted includes a contact type tool setting instrument and a laser tool setting instrument.

[0036] As the further specific optimization of the technical scheme of the application, the tool length detection instrument adopted can accurately detect the tool length of the main shaft, and the repeated accuracy can reach 0.1 μm.

[0037] As the further specific optimization of the technical scheme of the application, in order to ensure high-precision measurement, the workshop environment temperature interval is required to be 10℃-35℃, the temperature change is within ±1℃, and the workshop is far away from other heat sources and vibration sources.

[0038] As the further specific optimization of the technical scheme of the application, the in-machine measurement data is accurately compensated by fitting the change curve of the thermal elongation of the main shaft and time.

[0039] As the further specific optimization of the technical scheme of the application, according to the measurement time of each measurement point in the actual in-machine measurement application, the compensation value on the change curve of the thermal elongation of the main shaft is obtained to complete the compensation of the measurement result.

[0040] As the further specific optimization of the technical scheme of the application, whether the result compensation is needed is determined according to the measurement time, the change curve of the main shaft and other factors during the compensation, and the one-key compensation is completed by running the thermal balance compensation program.

[0041] Compared with the prior art, the application has the following advantages:

[0042] Advantage 1: The application improves the detection efficiency and result accuracy of in-machine measurement. The application realizes accurate detection of the change of the thermal elongation of the main shaft. Combined with a precise tool length detection instrument, the change of the tool length of the main shaft can be accurately obtained, and the highest accuracy can reach 0.1 μm. The relationship curve of the thermal elongation of the main shaft with time is obtained by mathematical formula fitting, and the curve accurately reflects the thermal elongation change characteristics of the main shaft of the machine tool.

[0043] Advantage 2: The application realizes accurate compensation of in-machine measurement results. Through the calibration program, the parameter values in the fitting curve can be obtained. In the measurement process, whether the measurement result needs to be compensated is selected. During the compensation, according to the initial tool setting length l1 and the end tool setting length l ’ 1, the compensation amount in the curve corresponding to the time of each detection point, the accurate compensation of the in-machine measurement result is realized.

[0044] Additional aspects and advantages of the application will be partially given in the following description, partially will become obvious from the following description, or will be understood by the practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0045] 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 embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0046] Figure 1 is a schematic diagram of the spindle thermal elongation detection and compensation method of the present application;

[0047] Figure 2 is a spindle thermal elongation change rule curve diagram of the spindle thermal elongation detection and compensation method of the present application;

[0048] Figure 3 is a flowchart of the spindle thermal elongation detection and compensation method of the present application;

[0049] Figure legend: 1, machine tool spindle; 2, tool holder; 3, tool; 4, tool length detection instrument. DETAILED DESCRIPTION

[0050] The exemplary embodiments disclosed by the present application will be described in detail with reference to the accompanying drawings, which are provided in order to enable a more thorough understanding of the present application and to enable the complete disclosure of the scope of the present application to be conveyed to those skilled in the art. Although the exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application should not be limited by the embodiments described herein.

[0051] A spindle thermal elongation detection and compensation method, the hardware includes machine tool spindle 1, tool holder 2, tool 3 and tool length detection instrument 4 and other components. The tool 3 is installed on the spindle 1 using the tool holder 2, and the machining of the part product is carried out; the tool length detection instrument 4 is fixed on the machine tool workbench and does not move, and the tool length detection instrument 4 has a self-cleaning function, which can clean the detection instrument 4 and the tool 3 during the detection process, ensure that there is no oil stain and waste during the detection process, and ensure the accuracy of the spindle tool length detection.

[0052] The spindle thermal elongation change detection is obtained by detecting the length change of the spindle tool. The length of the spindle tool 3 is continuously detected by the tool length detection instrument 4, so that the change rule of the spindle thermal elongation can be obtained. During the detection process, the environmental temperature is required to be in the range of 10-35℃, the temperature change is required to be within ±1℃, and the detection machine tool is required to be far away from other heat sources and vibration sources to prevent the influence of other heat sources and vibration sources on the spindle thermal elongation change detection; during the detection process, the spindle Z-direction displacement amount is required to be as small as possible to remove the thermal deformation caused by the movement of the screw and the guide rail and to introduce errors in the detection of the length of the spindle tool; generally, the continuous detection time is required to be greater than 1h, and the spindle of the machine tool is required to be restored to the cold state at the end of the detection to ensure the integrity of the detection process.

[0053] Using the above method, the spindle thermal elongation change is tested and verified, and the spindle thermal elongation change rule curve is obtained, as shown in Figure 2 The figure shows that: the spindle generally presents a shrinkage change phenomenon after the machining is completed, and the shrinkage amount will cause a large error in the measurement result; the spindle thermal elongation changes rapidly in the first 30min, and presents a large rapid shrinkage; the change is gradually smooth in the last 30min, and tends to be stable; and a small amplitude of the spindle length elongation change is found in the first 2min, which is caused by the hysteresis of the influence of the spindle temperature on the thermal elongation change; the spindle thermal elongation change is small in the first 5min, and has a small influence on the in-machine measurement data. The change rule curve of the spindle provides sufficient and reliable basis for the compensation of the in-machine measurement result.

[0054] According to the above process, the "spindle thermal equilibrium calibration" program and the "spindle thermal equilibrium compensation" program are developed. The calibration program can automatically realize the continuous detection process of the spindle tool length, and can obtain the spindle thermal elongation change characteristics of the detection machine tool by using mathematical formula for curve fitting according to the spindle tool length change obtained by detection. The parameter of the characteristic curve equation is stored in the corresponding variable of the numerical control system, and this method provides accurate compensation amount for the compensation of the in-machine measurement result. When compensation is needed, the accurate compensation of the measurement result can be quickly completed by running the compensation program.

[0055] The flow is shown in Figure 3

[0056] 1) Detect the spindle tool length in the cold state, and record it as l0;

[0057] 2) Calibrate using the "thermal equilibrium calibration program" to obtain the compensation function parameter value. The calibration of the spindle thermal elongation change rule must be performed before use;

[0058] 3) After the machining is completed, it is judged whether to perform the thermal elongation compensation of the spindle according to the measurement time. According to experimental experience, the following general rules are obtained:

[0059] ​① Measurement time is within 5 minutes, no compensation (the spindle elongation changes within 2 μm) ;

[0060] Measurement starts, first detect the tool length, save the current tool length as l1, then execute the measurement program, and complete the measurement;

[0061] ② Measurement time is more than 5 minutes, compensation is needed (the spindle elongation changes more than 2 μm) ;

[0062] Measurement starts, first detect the tool length, save the current tool length as l1, then execute the measurement program, and complete the measurement; ’ 1; manual export measurement data and corresponding measurement time, save as TXT document in the specified form; run "thermal compensation program", open the measurement data document and confirm according to the prompt, complete compensation and save;

[0063] Measurement starts, first detect the tool length, save the current tool length as l1, then execute the measurement program, and complete the measurement.

[0064] Optimized: the "spindle thermal compensation program" is a special calibration macro program, and its main purpose is to obtain the parameter value of the compensation function. The main logic of the program is:

[0065] 001, the program starts;

[0066] 002, detect the tool length as l0;

[0067] 003, the spindle starts at the warm-up speed and continuously detects the tool length as l i ;

[0068] 004, judge whether the stable warm-up reaches the stability, the judgment method: continuously detect the tool length for 5 times, the error of adjacent two times is not more than 0.2 μm, and the total error of 5 times is not more than 0.3 μm;

[0069] 005, the maximum calibration time is not more than 60 minutes, if it has not reached the stability at 60 minutes, record the tool length l ∞ at this time, and pop up a box to alarm;

[0070] 006, the program ends.

[0071] Optimized: the "compensation function" is a regular change function of the spindle thermal elongation characteristic, and its formula and parameter calculation formula are as follows:

[0072] L=a·e (b·t) +c (1),

[0073] Wherein: a is the thermal elongation coefficient; a=l0-l∞ , l ∞ Take the equilibrium state tool length, l0 take the measured tool length before;

[0074] b is the thermal elongation time coefficient; b = ln((l i -l ∞ ) / (l0-l ∞ )) / Δt, Δt = t i -t0; calibration, take 30mm time tool length to calculate b parameter value;

[0075] c is the equilibrium state tool length; c = l ∞ .

[0076] Optimized: the "measurement program" is by program writing software output or handwritten for workpiece features, size, allowance, etc. NC program for measurement; measurement data need to be recorded simultaneously.

[0077] Optimized: the "thermal equilibrium compensation program" is a special macro program for compensation processing of measurement data. Its compensation method is to determine the "compensation function" according to formula (1), calculate the corresponding thermal elongation compensation value under different measurement time, and add the compensation value to the original measurement value to complete the compensation.

[0078] Optimized: the tool length detector is used to continuously measure the spindle tool length, and the continuous change rule of the spindle thermal elongation is obtained; according to the change rule of the spindle thermal elongation, the measurement results of the detection point in the machine measurement are compensated, and more accurate measurement results are obtained.

[0079] Optimized: mainly for the change rule of the spindle thermal elongation after machine tool processing.

[0080] Optimized: its detection and compensation method is also applicable to the research of the spindle thermal elongation change rule under other working conditions.

[0081] Optimized: the change rule of the spindle thermal elongation after machine tool processing is studied, and the purpose is to compensate the influence of the spindle thermal elongation change on the measurement results in the application process of in-machine measurement.

[0082] Optimized: the tool length detector includes contact type tool detector and laser tool detector.

[0083] Optimized: the tool length detector can accurately detect the spindle tool length, and the repeatability can reach 0.1 μm.

[0084] Optimized: in order to ensure high-precision measurement, the workshop environment temperature interval is required to be 10℃-35℃, the temperature change is within ±1℃, and it is far away from other heat sources and vibration sources.

[0085] Optimized: the in-machine measurement data is accurately compensated by fitting the change curve of the spindle thermal elongation and time.

[0086] Optimized: according to the detection time of each measurement point in the actual in-machine measurement application, the compensation value on the corresponding spindle elongation change curve is obtained to complete the compensation of the measurement result.

[0087] Optimized: according to the detection time, spindle change curve and other factors, it is determined whether the result needs to be compensated, and one-key compensation is completed by running the "thermal balance compensation program".

[0088] 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 are described clearly and completely above in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0089] Therefore, the above detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments in the present application without making creative efforts are within the scope of protection of the present application.

[0090] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly placed when the product of the present application is used, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0091] In the description of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "arrangement", "installation", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

Claims

1. A method of spindle thermal elongation variation detection and compensation, characterized by, The method comprises the following steps: 1) detecting the spindle tool length in a cold state, and recording the length as l0; 2) before using the spindle thermal elongation change compensation, the spindle thermal equilibrium calibration needs to be performed first; the spindle thermal elongation change law is calibrated through a spindle thermal equilibrium calibration program, and compensation function parameter values are obtained; before use, the spindle thermal elongation change law must be calibrated; 3) after the machining is completed, whether the spindle thermal elongation compensation is performed is judged according to the measurement time; the following general law is obtained according to experimental experience: ① when the measurement time is within 5 minutes, no compensation is performed; the measurement is started, the measurement head tool length is detected first, the current tool length is saved as l1, then the measurement program is executed, and the measurement is completed; ② when the measurement time is more than 5 minutes, compensation needs to be performed; the measurement head tool length is detected first, the current tool length is saved as l1, then the measurement program is executed, the measurement head tool length is detected again after the measurement is completed, the current tool length is saved as l'1, the measurement data and the corresponding measurement time are manually exported, and are saved in a TXT document in a specified form; the thermal equilibrium compensation program is run, the measurement data document is opened according to the prompt and is confirmed, the compensation is completed and is saved; ③ when the measurement is performed after 30 minutes of cooling, no compensation is performed; the measurement is started, the measurement head tool length is detected first, the current tool length is saved as l1, then the measurement program is executed, and the measurement is completed.

2. The method of spindle thermal elongation variation detection and compensation according to claim 1, wherein, The spindle thermal equilibrium calibration program is a special calibration macro program, and the main purpose is to obtain the compensation function parameter values; the main logic of the program is as follows: 001, the program is started; 002, the tool length is detected as l0; 003、The main shaft opens the rotation speed to warm up, and continuously detects the tool length l i ; 004, whether the stable warm-up reaches the stability is judged; the judgment method is that the tool length is continuously detected for 5 times, the error of adjacent two times is not greater than 0.2 μm, and the total error of the 5 times is not greater than 0.3 μm; 005、Maximum calibration duration does not exceed 60 min, if not yet reached stable at 60 min, record the length of the knife l' ∞ And pop-up alarm prompt; 006, the program is ended.

3. The method of spindle thermal elongation variation detection and compensation according to claim 1, wherein, The compensation function is a regular change function of the spindle thermal elongation characteristic, and the formula and the parameter calculation formula are as follows: L = a e (b·t) + c (1), Where: a is the thermal elongation coefficient; a = l0 - l ∞ , l ∞ Take the equilibrium state tool length, l0Take the pre-measurement tool length; b is the thermal elongation time coefficient; b = ln((l i -l ∞ ) / (l0-l ∞ )) / Δt, Δt = t i -t0; the b parameter value is calculated by taking the length of the knife at 30 min. c is the length of the knife in the equilibrium state; c = l ∞ .

4. The method of spindle thermal elongation variation detection and compensation according to claim 1, wherein, The measurement program is an NC program for workpiece feature, size and allowance measurement which is output by a program writing software or is manually written; 5. The method of spindle thermal elongation variation detection and compensation according to claim 3, wherein, The thermal equilibrium compensation program is a special macro program for compensating the measurement data; The compensation method is to determine the compensation function according to formula (1), to calculate the thermal elongation compensation values corresponding to different measurement times, and to add the compensation values to the original measurement values to complete the compensation.

6. The method of spindle thermal elongation variation detection and compensation of claim 1, wherein, The spindle tool length is continuously measured by using a tool length detector, and the continuous change law of the spindle thermal elongation is obtained; the measurement results of the measurement points in the machine measurement are compensated according to the change law of the spindle thermal elongation, and more accurate measurement results are obtained.

7. The method of spindle thermal elongation variation detection and compensation according to claim 6, wherein, The tool length detector used includes a contact type tool detector and a laser tool detector.

8. The method of spindle thermal elongation variation detection and compensation according to claim 6, wherein, The in-machine measurement data is accurately compensated by fitting the change curve of the spindle thermal elongation and the time.

9. The method of spindle thermal elongation variation detection and compensation of claim 1, wherein, According to the measurement time of each measurement point in the actual in-machine measurement application, the compensation values on the change curve of the corresponding spindle thermal elongation are obtained to complete the compensation of the measurement results.

10. The method of spindle thermal elongation variation detection and compensation of claim 1, wherein, Whether the result compensation needs to be performed is determined according to the measurement time and the spindle change curve factors, and the one-key compensation is completed by running the thermal equilibrium compensation program.

Images