CN113093647B - Method and device for identifying reverse gap based on response data of numerical control machine tool - Google Patents
Method and device for identifying reverse gap based on response data of numerical control machine tool Download PDFInfo
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- G05B19/401—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes
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Abstract
The utility model discloses a method and a device for identifying a reverse gap based on response data of a numerical control machine, belonging to the technical field of numerical control and comprising the following steps: when the numerical control machine tool executes a reverse instruction, the method isCommand speed signal v generated by target horizontal feed shaftc(t), current signal I (t), encoder displacement signal pe(t) and encoder speed signal ve(t) obtaining the time t at which the commanded speed crosses zero in the commanded speed signal0And then a time t separated therefrom by a predetermined time period3(ii) a Delaying the time in the encoder speed signal relative to the commanded speed signal by an amount eiEliminate to obtain a command speed signal vc(t‑ei) According to ev(t)＝vc(t‑ei)‑ve(t) calculating the velocity difference ev(t); calculating the speed difference ev(t) during a time period t0～t3At the time of mutation t in (1)1And the current signal I (t) during a time period t0～t3At the time of mutation t in (1)2(ii) a Calculating an encoder displacement signal pe(t) during a time period t1～t2The resulting displacement increment, whose absolute value is identified as the reverse gap. The utility model can improve the identification precision and realize the dynamic reverse clearance identification of the semi-closed loop control machine tool.
Description
Technical Field
The utility model belongs to the technical field of numerical control, and particularly relates to a reverse gap identification method and device based on numerical control machine tool response data.
Background
The reverse clearance of the numerical control machine tool is characterized in that the reverse clearance of the numerical control machine tool is a mechanical clearance from the head end of a machine tool kinematic chain to the whole process of an executive component, so that when the executive component of the machine tool moves from a forward direction to a reverse direction, the error between the movement amount of the executive component and a theoretical value is represented as a larger nonlinear following error when a feeding system moves in the reverse direction and a larger over-quadrant projection when a circle drawing outline instruction is executed, the machining precision of the machine tool is reduced, and particularly for a high-precision machine tool, the improvement of the precision of the machine tool is limited due to the existence of the reverse clearance. It is therefore particularly important to accurately measure and compensate for the reverse gap.
The reverse clearance exists at the joint of mechanical parts, and comprises a clearance between a motor shaft and a gear shaft due to key coupling, a clearance between a gear pair, a clearance between a gear and a lead screw due to key coupling, a clearance between a coupler and a key coupling, a lead screw nut clearance and the like, so that direct measurement cannot be carried out.
The dial indicator is used for manual measurement, the measurement process is simple, the whole-process operation of measurement personnel is needed, large manual measurement errors exist, and the dial indicator is mainly used for occasions with large reverse clearances.
Although the laser interferometer has higher measurement precision, the laser interferometer also has the defects of manual measurement error and low automation degree. Meanwhile, the two measurement modes are used for reading under the condition that the feeding shaft is static, the measured reverse clearance is static and cannot reflect the relation between the reverse clearance and the feeding speed, and the reference significance of a static measurement result on the function of compensating the reverse clearance at different speeds of the numerical control machine tool is not large.
At present, a common method is to use a grating scale to measure the reverse gap, for example, in patent document CN2013107369370 entitled "method for monitoring reverse gap of numerically controlled machine tool with full closed loop servo system", the difference of grating scale data at the same encoder position before and after the reverse direction is recorded by the grating scale and the encoder on the full closed loop machine tool as the value of the reverse gap at that point. The method avoids the influence of Abbe errors caused by using a laser interferometer, and can measure the reverse clearance of the whole process of the machine tool, but most of machine tools used in the current factory are semi-closed loop machine tools, and the measuring condition can not be realized.
In addition to the above-mentioned conventional measurement methods, there are also methods for identifying the mechanical clearance based on the current signal of the machine tool in the current research.
In patent document CN2015105593135 entitled "method for predicting wear state of ball screw of numerical control machine tool", this method considers that the wear amount of the screw is the size of the reverse gap, and collects three-phase current i of the numerical control machine toolu、iv、iwCalculating to obtain root mean square value
And after the wavelet packet component of the signal sensitive section is reconstructed, the variance is obtained to be used as the prediction of the wear state of the screw rod. Although the method is sufficiently compactThe wear condition of the ball screw is determined, but the wear amount-characteristic amount curves obtained in different machine tools are different, and the wear amount of the reverse clearance cannot be calculated quantitatively.
In the paper "servo system online transmission gap identification and its negative effect suppression", the drive motor is controlled with a triangular wave velocity signal, and the gap amplitude is identified by calculating the integral of the velocity difference between the time t1 when the gears are disengaged and the time t2 when they are reengaged. However, the torque current fluctuates and has high speed, and the spikes are more after differentiation, so that the detection at the time t1 and the time t2 is inaccurate.
In general, the existing method for identifying the reverse clearance of the numerical control machine tool has the technical problems that the identification precision is low, and the dynamic reverse clearance identification of a semi-closed loop control machine tool cannot be realized.
Disclosure of Invention
Aiming at the defects and improvement requirements of the prior art, the utility model provides a reverse clearance identification method and a reverse clearance identification device based on numerical control machine tool response data, and aims to solve the technical problems that the existing numerical control machine tool reverse clearance identification method is low in identification precision and cannot realize dynamic reverse clearance identification of a semi-closed loop control machine tool.
To achieve the above object, according to one aspect of the present invention, there is provided a reverse gap identification method based on response data of a numerical control machine, including:
extracting a command speed signal v generated by the numerical control machine tool on a target horizontal feed shaft when executing a reverse commandc(t), current signal I (t), encoder displacement signal pe(t) and encoder speed signal ve(t) obtaining the time t at which the commanded speed crosses zero in the commanded speed signal0And time t0After and spaced therefrom by a predetermined time tlastAt time t3；
Encoder speed signal ve(t) relative to the command velocity signal vcTime delay e of (t)iAfter elimination, a synchronized command velocity signal v is obtainedc(t-ei) According to ev(t)＝vc(t-ei)-ve(t) calculating the velocity difference ev(t); respectively calculating the speed difference ev(t) during a time period t0～t3At the time of mutation t in (1)1And the current signal I (t) during a time period t0～t3At the time of mutation t in (1)2；
Calculating an encoder displacement signal pe(t) during a time period t1～t2The displacement is incremented and its absolute value is identified as the reverse gap.
In actual operation of the machine tool, obvious nonlinear following errors occur at the reverse motion, the following errors are difficult to eliminate only by PID control, and the main factors causing the nonlinear following errors are reverse clearance and friction force. A mechanical play exists between the screw and the nut, the screw moving against the nut before the reverse process begins. The technical principle of the utility model for identifying the reverse gap is as follows:
(1) at the time when the command speed is zero, the reverse process begins, and the encoder reverse time is delayed to t due to the hysteresis of the command response1Time of day;
(2)t1at the moment, the encoder moves towards the reverse direction, the lead screw is separated from the nut at the moment due to the existence of the reverse gap, the lead screw is in a no-load state at the moment, the acceleration is increased, the speed of the encoder is suddenly increased relative to the slowly-changed command speed, and the starting moment of the gap period corresponds to the sudden-change moment of the speed;
(3) after the encoder passes through the clearance length, the clearance period is ended, the screw rod is contacted with the nut again, but because the friction force value is larger at low speed, the current is increased in order to overcome the friction force to drive the load to move, and the position with the largest current change rate in the reverse direction is t2；
(4) Time period t1～t2The absolute value of the displacement increment of the inner encoder is the size of the reverse gap.
The utility model obtains the moment t of the zero crossing of the command speed in the command speed signal0And time t0After and spaced therefrom by a predetermined time tlastAt time t3From which a reverse data segment, i.e. time segment t, can be determined0～t3By reasonably setting the preset time tlastCan ensure that the whole process of the occurrence of the reverse gap is contained in the determined time period t0～t3Therefore, the utility model can accurately find the reverse data segment by using the instruction data with less fluctuation, and further can find the reverse data segment in the time period t0～t3The specific time period of occurrence of the reverse gap is determined, so that the target range can be reduced, the problem of inaccurate identification parameters is effectively reduced, and the identification precision is improved.
The utility model can complete the identification of the reverse clearance only by extracting the response data of the machine tool from the servo without other measuring tools such as a grating ruler and the like, and the extraction of the response data can not influence the normal operation of the numerical control machine tool, so the utility model can realize the dynamic reverse clearance identification of the semi-closed loop control machine tool without measuring equipment such as the grating ruler and the like.
Further, the air conditioner is provided with a fan,
wherein, T represents the track cycle of the numerically controlled machine tool.
Experiments show that the duration of the reverse gap does not exceed 1/20 of the track period T, the duration of the reverse gap is set to 1/20 of the track period, the reverse data segment can be accurately determined, and the identification speed can be effectively accelerated while the identification precision is ensured.
Further, the time t at which the commanded speed in the commanded speed signal crosses zero0The criterion is as follows:
vc(t0)*vc(t0+1)＜0；
or, vc(t0)*vc(t0+2) < 0 and vc(t0+1)＝0。
The moment t of the zero crossing of the command speed in the command speed signal can be accurately judged through the criterion0I.e., the start time of the reverse data segment, is advantageous for accurately determining the reverse data segment.
Further, the current signal I (t) is in the time period t0～t3At the time of mutation t in (1)2The calculation method is as follows:
low-pass filtering the current signal I (t) and differentiating to obtain a signal dIlow(t)；
Find signal dIlow(t) during a time period t0～t3The extreme value moment in (1) is the time period t of the current signal I (t)0～t3At the time of mutation t in (1)2。
When the machine tool runs, the interference of high-frequency signals such as vibration, electromagnetic interference and the like exists, so that the directly acquired current signals are relatively disordered.
Further, the method for identifying the reverse gap based on the response data of the numerical control machine further comprises the following steps: the identified reverse gap is compensated.
The utility model compensates the identified reverse clearance on the machine tool which accurately identifies the reverse clearance, and can effectively improve the processing precision of the numerical control machine tool.
According to another aspect of the present invention, there is provided a reverse gap recognition apparatus based on response data of a numerical control machine, comprising: the device comprises a data extraction module, a reverse data segment marking module, a gap period identification module and a reverse gap identification module;
a data extraction module for extracting the command speed signal v generated by the numerical control machine tool on the target horizontal feed shaft when executing the reverse commandc(t), current signals I (t), encoder displacement signals pe(t) and encoder speed signal ve(t)；
A backward data segment marking module for obtaining the zero-crossing time t of the instruction speed in the instruction speed signal0And time t0After and spaced therefrom by a predetermined time tlastAt time t3；
A gap period identification module for identifying the encoder speed signal ve(t) relative to the command velocity signal vcTime delay e of (t)iAfter elimination, a synchronized command velocity signal v is obtainedc(t-ei) According to ev(t)＝vc(t-ei)-ve(t) calculating a velocity difference ev(t); a gap period identification module for respectively calculating the speed difference ev(t) during a time period t0～t3At the time of mutation t in (1)1And the current signal I (t) during a time period t0～t3At the time of mutation t in (1)2；
A reverse gap identification module for calculating the encoder displacement signal pe(t) during a time period t1～t2The displacement is incremented and its absolute value is identified as the reverse gap.
The utility model provides a reverse gap identification device based on response data of a numerical control machine tool, which further comprises: a reverse gap compensation module;
and the reverse clearance compensation module is used for compensating the reverse clearance identified by the reverse clearance identification module.
According to yet another aspect of the present invention, there is provided a computer readable storage medium comprising a stored computer program; when the computer program is executed by the processor, the computer readable storage medium is controlled to execute the method for identifying the reverse gap based on the response data of the numerical control machine tool provided by the utility model.
Generally, by the above technical solution conceived by the present invention, the following beneficial effects can be obtained:
the utility model provides a method and a device for identifying a reverse gap based on response data of a numerical control machine tool, which are characterized in that firstly, a reverse gap data segment is identified, the starting time of the reverse gap data segment is the time of an instruction speed process, and the ending time of the reverse gap data segment is the time of a preset duration after the starting time; further identifying the starting time and the ending time of a 'gap period' in the reverse gap data segment, wherein the starting time is the time when the speed in the reverse gap data segment changes suddenly, and the ending time is the time when the current signal changes suddenly; finally, the displacement increment of the encoder of the numerical control machine tool between the start time and the end time of the "gap period" is recognized as a reverse gap. Therefore, the identification of the reverse clearance can be completed and the identification precision can be improved based on the technical principle that the response data of the machine tool in each control period is closely related to the state of the machine tool in the machining control process of the numerical control system and the specific principle of the generation of the reverse clearance; the utility model can complete the identification of the reverse clearance without other measuring tools such as a grating ruler and the like only by extracting the response data of the machine tool from the servo without influencing the normal operation of the numerical control machine tool, so the utility model can realize the dynamic reverse clearance identification of the semi-closed loop control machine tool without measuring equipment such as the grating ruler and the like.
Drawings
Fig. 1 is a flowchart of a method for identifying a reverse gap based on response data of a numerical control machine according to an embodiment of the present invention;
FIG. 2 is a schematic view of a mechanical feeding structure of a conventional chicken machine tool;
FIG. 3 is a control block diagram of a prior art Baoji machine tool;
fig. 4 is a schematic diagram of calculating a reverse gap according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and do not limit the utility model. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
In the present application, the terms "first," "second," and the like (if any) in the description and the drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
In order to solve the technical problems that the existing method for identifying the reverse clearance of the numerical control machine tool is low in precision and cannot realize dynamic reverse clearance identification of a semi-closed loop control machine tool, the utility model provides a method and a device for identifying the reverse clearance based on response data of the numerical control machine tool, and the overall thought is as follows: directly utilizing response data of the numerical control machine tool to carry out identification, firstly identifying a reverse gap data segment, wherein the starting time of the reverse gap data segment is the time of the command speed process, and the ending time of the reverse gap data segment is the time after the preset time length after the starting time; further identifying the starting time and the ending time of a 'gap period' in the reverse gap data segment, wherein the starting time is the time when the speed in the reverse gap data segment changes suddenly, and the ending time is the time when the current signal changes suddenly; finally, identifying the displacement increment of the encoder of the numerical control machine tool as a reverse gap between the starting time and the ending time of the gap period; therefore, the identification precision of the reverse clearance is improved, dependence on other measuring tools such as a grating ruler is avoided, and influence on normal operation of the numerical control machine tool is avoided, so that dynamic reverse clearance identification of the semi-closed loop control machine tool is realized.
The following are examples.
Example 1:
a method for identifying a reverse gap based on response data of a numerical control machine, as shown in fig. 1, includes:
extracting a command speed signal v generated by the numerical control machine tool on a target horizontal feed shaft when executing a reverse commandc(t), current signal I (t), encoder displacement signal pe(t) and encoder speed signal ve(t) obtaining the time t at which the commanded speed crosses zero in the commanded speed signal0And time t0After and spaced therefrom by a predetermined time tlastAt time t3(ii) a The reverse instruction is an instruction pulse signal which is sent by a machine tool numerical control system and has a motion direction opposite to that of the previous control cycle; in practical applications, the target horizontal feeding axis may be a horizontal feeding x-axis or a horizontal feeding y-axis, and the method for identifying the reverse gap in each horizontal feeding axis direction is the same, and without loss of generality, in this embodiment, the target horizontal feeding axis is specifically a horizontal feeding x-axis; the numerical control machine tool is provided with a matched encoder and a matched sensor in each feeding direction, and it is easy to understand that response data are acquired from the encoder and the sensor in the corresponding feeding direction when a target horizontal feeding shaft is subjected to reverse gap identification;
encoder speed signal ve(t) relative to the command velocity signal vcTime delay e of (t)iAfter elimination, a synchronized command velocity signal v is obtainedc(t-ei) And according to ev(t)＝vc(t-ei)-ve(t) calculating the velocity difference ev(t); respectively calculating the speed difference ev(t) during a time period t0～t3At the time of mutation t in (1)1And the current signal I (t) during a time period t0～t3At the time of mutation t in (1)2；
Calculating an encoder displacement signal pe(t) during a time period t1～t2Generating displacement increment and identifying the absolute value of the displacement increment as a reverse clearance;
in actual operation of the machine tool, obvious nonlinear following errors occur at the reverse motion, the following errors are difficult to eliminate only by PID control, and the main factors causing the nonlinear following errors are reverse clearance and friction force. A mechanical play exists between the screw and the nut, the screw moving against the nut before the reverse process begins. The technical principle of the utility model for identifying the reverse gap is as follows:
(1) at the time when the command speed is zero, the reverse process begins, and the encoder reverse time is delayed to t due to the hysteresis of the command response1Time of day;
(2)t1at the moment, the encoder moves in the reverse direction, because of the existence of a reverse gap, the lead screw is separated from the nut at the moment, the lead screw is in a no-load state at the moment, the acceleration is increased, the speed of the encoder is suddenly increased relative to the slowly-changed command speed, and the moment of sudden change of the speed corresponds to the starting moment of a gap period;
(3) after the encoder passes through the clearance length, the clearance period is ended, the screw rod is contacted with the nut again, but because the friction force value is larger at low speed, the current is increased in order to overcome the friction force to drive the load to move, and the position with the largest current change rate in the reverse direction is t2；
(4) Time period t1～t2The absolute value of the displacement increment of the inner encoder is the size of the reverse gap.
The utility model obtains the moment t of the zero crossing of the command speed in the command speed signal0And time t0After and spaced therefrom by a predetermined time tlastTime t of3From which a reverse data segment, i.e. time segment t, can be determined0～t3By reasonably setting the preset time tlastCan ensure that the whole process of the occurrence of the reverse gap is contained in the determined time period t0～t3In the practical application,
in the present embodiment, the first and second electrodes are,
wherein T represents the track period of the numerical control machine tool.
Experiments show that the duration of the reverse gap does not exceed 1/20 of the track period T, and the duration of the reverse gap is set to 1/20 of the track period, so that the reverse data segment can be accurately determined, and the identification speed can be effectively accelerated while the identification precision is ensured; it should be noted that the present invention is only an alternative embodiment, and should not be construed as the only limitation to the present invention, and in practical application, t can be directly set for a real numerically controlled machine tool with the duration of the reverse gap thereof knownlastThe value of (1).
As an optional implementation manner, in this embodiment, the time t when the instruction speed in the instruction speed signal crosses zero is the time t0The criterion is as follows:
vc(t0)*vc(t0+1)＜0；
or, vc(t0)*vc(t0+2) < 0 and vc(t0+1)＝0。
The moment t of the zero crossing of the command speed in the command speed signal can be accurately judged through the criterion0I.e., the start time of the reverse data segment, is advantageous for accurately determining the reverse data segment.
As an alternative implementation, in the present embodiment, the current signal i (t) is in the time period t0～t3Time t of mutation in (1)2The calculation method is as follows:
low-pass filtering the current signal I (t) and differentiating to obtain a signal dIlow(t)；
Find signal dIlow(t) during a time period t0～t3The extreme value moment in (1) is the time period t of the current signal I (t)0～t3Time t of mutation in (1)2。
When the machine tool runs, the interference of high-frequency signals such as vibration, electromagnetic interference and the like exists, so that the directly acquired current signals are relatively disordered.
The method for identifying the reverse gap based on the response data of the numerical control machine further comprises the following steps: the identified reverse gap is compensated.
The utility model compensates the identified reverse clearance on the machine tool which accurately identifies the reverse clearance, and can effectively improve the processing precision of the numerical control machine tool.
Example 2:
a reverse gap identification device based on numerical control machine tool response data comprises: the device comprises a data extraction module, a reverse data segment marking module, a gap period identification module, a reverse gap identification module and a reverse gap compensation module;
a data extraction module for extracting the command speed signal v generated by the numerical control machine tool on the target horizontal feed shaft when executing the reverse commandc(t), current signal I (t), encoder displacement signal pe(t) and encoder speed signal ve(t)；
A backward data segment marking module for obtaining the zero-crossing time t of the instruction speed in the instruction speed signal0And time t0After and spaced by a predetermined time period tlastAt time t3；
A gap period identification module for identifying the encoder speed signal ve(t) relative to the command velocity signal vcTime delay e of (t)iAfter elimination, a synchronized command speed signal v is obtainedc(t-ei) According to ev(t)＝vc(t-ei)-ve(t) calculating the velocity difference ev(t); a gap period identification module for respectively calculating the speed difference ev(t) during a time period t0～t3Time t of mutation in (1)1And the current signal I (t) during a time period t0～t3At the time of mutation t in (1)2；
A reverse gap identification module for calculating the encoder displacement signal pe(t) during a time period t1～t2Generating a displacement increment and identifying the absolute value thereof as a reverse gap;
the reverse clearance compensation module is used for compensating the reverse clearance identified by the reverse clearance identification module;
in this embodiment, the detailed implementation of each module may refer to the description in the above method embodiment, and will not be repeated here.
Example 3:
a computer readable storage medium comprising a stored computer program; when the computer program is executed by the processor, the apparatus on which the computer readable storage medium is located is controlled to execute the method for identifying a reverse gap based on response data of a cnc machine as provided in the above embodiment 1.
The beneficial effects of the present invention will be further described by taking the application of the above embodiment in BM8-H Bao chicken vertical processing center as an example. The servo feeding system of the BM8-H chicken numerical control machine tool is structurally shown in figure 2, the machine tool adopts a ball screw transmission system, and the ball screw converts rotary motion into linear motion of a workbench through a nut; as shown in fig. 3, the machine tool adopts semi-closed loop control, the feedback signal of the position loop is from the rotary displacement of the input end of the screw rod measured by the incremental encoder of the motor, the feedback of the speed loop is from the differential value fed back by the position loop, and the feedback of the current loop is from the current of the driving motor; in order to compare the identification precision of the utility model, grating rulers are arranged on the X-axis workbench and the Y-axis workbench of the machine tool; the numerical control system is a Chinese 8 type domestic numerical control system.
For the X-axis of feed, the specific identification process is as follows:
s1: the machine tool executes the position triangular wave command signal of F3000, and the machine tool moves in the forward direction and the reverse direction;
s2: setting a machine tool data acquisition software channel, and acquiring a command speed signal vc (t) of a feeding X axis, a current signal I (t) and an encoder displacement pe(t) encoder speed signal ve(t)；
S3, automatic marking of the reverse process: according to a command speed zero crossing criterion: v. ofc(t0)*vc(t0+1) < 0 or vc(t0)*vc(t0+2) < 0 and vc(t0+1) is 0, accurately finding out the zero crossing point t of the instruction speed03359ms, the reverse duration does not exceed 1/20 of the trajectory period, so the reverse duration is made
Thus t33547ms, interval of interval 3359,3547]；
S4: beginning of the gap period t1And an end time t2Determination of (1): based on the collected response data, the time delay of the encoder speed relative to the command speed is eiThe difference is made for 15ms to obtain a speed difference ev(t); at t0～t3In (e)v(t) the mutation time corresponding to t is t13382 ms; subjecting the current signal I (t) to a 50Hz low-pass filtering and differentiating dIlow(t) at t0～t3To find the instant of the abrupt change in the current signal, i.e. dIlow(t) corresponding extreme time t2＝3386ms；t1And t2The corresponding encoder increment is 1.5 mu m; the gap value of the grating ruler measured under F3000 is 1.6 μm, and the identification error is 6.7%; under the same speed, other identification methods without the help of a grating ruler often have an identification error of more than 20 percent, so that the identification error is known,the identification method provided by the utility model has high identification precision.
The determined reverse data segment (i.e. time segment t)0～t3) And the starting time t of the gap period in the time period1And an end time t2The calculation method of (2) is shown in fig. 4.
According to the same method, the numerical control machine tool executes the triangular wave command signals of F1000, F6000 and F8000 positions on the feeding X axis; according to the same method, the zero numerical control machine executes triangular wave command signals of F1000, F3000, F6000 and F8000 positions on the feeding Y axis; the reverse gap identified based on the method provided in the above embodiment and the reverse gap directly measured using the grating ruler are shown in table 1. According to the results shown in table 1, the maximum error is only 16% at different speeds, and thus the method for identifying the reverse gap based on the response data of the numerical control machine tool provided by the utility model has higher identification accuracy.
TABLE 1 gap identification results of Bao Chicken machine tool at different speeds
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the utility model, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (8)
1. A reverse gap identification method based on numerical control machine tool response data is characterized by comprising the following steps:
extracting a command speed signal v generated by the numerical control machine tool on a target horizontal feed shaft when executing a reverse commandc(t), current signal I (t), encoder displacement signal pe(t) and encoder speed signal ve(t) obtaining a time t at which a commanded speed in said commanded speed signal crosses zero0And said time t0After and at a predetermined intervalDuration tlastAt time t3；
(iv) converting the encoder speed signal ve(t) relative to said commanded speed signal vcTime delay e of (t)iAfter elimination, a synchronized command speed signal v is obtainedc(t-ei) According to ev(t)＝vc(t-ei)-ve(t) calculating the velocity difference ev(t); respectively calculating the speed difference ev(t) during said time period t0～t3At the time of mutation t in (1)1And the current signal I (t) during the time period t0～t3At the time of mutation t in (1)2；
Calculating the encoder displacement signal pe(t) during a time period t1～t2The displacement is incremented and its absolute value is identified as the reverse gap.
2. The method of claim 1, wherein the back gap recognition based on the response data of the NC machine tool is performed by a computer,
wherein T represents the track period of the numerical control machine tool.
3. The method of claim 1, wherein the time t when the command speed crosses zero in the command speed signal is the reverse gap identification method based on the response data of the numerical control machine tool0The criterion is as follows:
vc(t0)*vc(t0+1)＜0；
or, vc(t0)*vc(t0+2) < 0 and vc(t0+1)＝0。
4. The method of claim 1, wherein the current signal i (t) is generated during the time period t0～t3Time t of mutation in (1)2The calculation method is as follows:
carrying out low-pass filtering on the current signal I (t) and then differentiating to obtain a signal dIlow(t)；
Find the signal dIlow(t) during said time period t0～t3The extreme value moment in (1) is the time of obtaining the current signal I (t) in the time period t0～t3At the time of mutation t in (1)2。
5. The method for identifying a reverse gap based on numerical control machine tool response data according to any one of claims 1 to 4, further comprising: the identified reverse gap is compensated.
6. A reverse gap identification device based on numerical control machine tool response data is characterized by comprising: the device comprises a data extraction module, a reverse data segment marking module, a gap period identification module and a reverse gap identification module;
the data extraction module is used for extracting a command speed signal v generated by the numerical control machine tool on a target horizontal feed shaft when executing a reverse commandc(t), current signal I (t), encoder displacement signal pe(t) and encoder speed signal ve(t)；
The reverse data segment marking module is used for obtaining the moment t of the command speed zero crossing in the command speed signal0And said time t0After and spaced therefrom by a predetermined time tlastAt time t3；
The gap period identification module is used for identifying the encoder speed signal ve(t) relative to said command velocity signal vcTime delay e of (t)iAfter elimination, a synchronized command velocity signal v is obtainedc(t-ei) According to ev(t)＝vc(t-ei)-ve(t) calculating the velocity difference ev(t); the gap period identification module is also used for respectively calculating the speed difference ev(t) during said time period t0～t3At the time of mutation t in (1)1And the current signal I (t) during the time period t0～t3At the time of mutation t in (1)2；
The reverse gap identification module is used for calculating the encoder displacement signal pe(t) during a time period t1～t2The displacement is incremented and its absolute value is identified as the reverse gap.
7. The apparatus for identifying a reverse gap based on numerical control machine tool response data according to claim 6, further comprising: a reverse gap compensation module;
and the reverse clearance compensation module is used for compensating the reverse clearance identified by the reverse clearance identification module.
8. A computer-readable storage medium comprising a stored computer program; the computer program, when executed by a processor, controls an apparatus on which the computer readable storage medium is located to perform the method for identifying a reverse gap based on numerical control machine tool response data according to any one of claims 1 to 5.
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