Summary of the invention
Technical matters to be solved by this invention provides a kind of cmm accuracy compensation method; Utilization the method can be demarcated the measuring error of coordinate measuring machine quickly and accurately and compensated; Running time is short, and is affected by environment little, and the offset data reliability is high.
The technical scheme that technical solution problem of the present invention is adopted is: this method may further comprise the steps:
Step 1) is utilized the cad model of coordinate measuring machine self, sets several measurement points, writes down the coordinate parameters of each measurement point, and the operating path of each measurement point of setting approach;
Step 2) end with first adapter rod is connected with cantilever, and at the other end of said first adapter rod target is installed;
Step 3) is fixed and is started laser tracker, regulates the light direction of laser tracker, makes laser beam irradiation on said target;
Step 4) starts coordinate measuring machine; Main frame is according to the output command operation of control system; Make target according to the path movement of setting in the step 1), laser tracker is followed the tracks of target, and the distance between each test point recording laser tracker and target and the angle value of laser-beam deflection;
The step 5) control system calculates the setpoint distance value between each measurement point, draws data set a1, the input computing machine; Laser tracker calculates the measuring distance value that target moves between each measurement point, draw data set b1, the input computing machine;
Step 6) computing machine comparing data group a1 and data set b1 calculate the range accuracy offset, and feed back to control system and compensate.
Laser tracker is followed target all the time, gathers the coordinate parameters of target in real time, and the disposable collection of the parameter of all measurement points is accomplished; Reduce the adjustment number of times, save time, and because Measuring Time is short; Measurement environment changes little relatively; Laser tracker is affected by environment, and especially temperature effect is little, and measurement data is more accurate.
For obtaining more comprehensively precision parameter, further comprising the steps of:
Step 7) is pulled down first adapter rod, second adapter rod that changes the outfit, repeating step 3) and step 4);
The step 8) control system calculates the setting vector value between each measurement point, draws data set a2, the input computing machine; Laser tracker calculates the measurement vector value of target between each measurement point, draws data set b2, the input computing machine;
Step 9) computing machine relatively array calculates vectorial accuracy compensation value according to a2 and data set b2, and feeds back to coordinate measuring machine and compensate.
Through using two adapter rod that length is different, draw the vectorial parameter between the measurement point, existing distance value has angle value again, and offset data is more comprehensive, and is more accurate to the compensation of coordinate measuring machine.
The device that is used for this cmm accuracy compensation method comprises coordinate measuring machine and computing machine, and said coordinate measuring machine comprises main frame and control system, and said main frame is provided with cantilever, also comprises laser tracker, target and first adapter rod; Said computing machine is connected with laser tracker with said control system respectively, and an end of said first adapter rod is connected with said cantilever, and the other end is connected with said target.
Be performing step 7) to step 9), also comprise second adapter rod, the length of said second adapter rod is different with the length of said first adapter rod.
The invention has the beneficial effects as follows: the compensation method of this cmm accuracy is creationary to be used in laser tracking technology in the demarcation to coordinate measuring machine; Measure coordinate measuring machine through laser tracker, target and two different adapter rod of length and move in the space site error of any arbitrarily, and draw the accuracy compensation data through Computing.This method is significantly increased than the efficient of traditional scaling method, and the data that obtain are more comprehensive, more can reflect real conditions, and compensation method is science more also, and is more accurate.Only need at initial point laser to be calibrated with group appearance and target, pilot process need not adjustment, so the nominal time is short, the error effect that environmental factors such as temperature are gathered data is less relatively.
The precision compensation method of coordinate measuring machine is that the parameter calibration with the coordinate measuring machine actual motion comes out on the whole, compares with the parameter of program setting, draws offset through computed in software.
Mode as shown in Figure 1, that the present invention adopts Laser Tracking to demarcate continuously.First adapter rod 7 and target 6 is installed on cantilever 4, and laser tracker 5 can be arranged on the pedestal of main frame 1, also can be arranged on ground or other fixed positions.The control system 2 of laser tracker 5 and coordinate measuring machine all is connected with computing machine 3.Target 6 can serve as that axle rotates on X, Y, three directions of Z with the beam reflection point of self.Laser tracker 5 is same as the laser interferometer of measuring equipment and classic method use, need not consider the error of self, after demarcating through relevant departments, can be used as benchmark.Certainly, because the high and laser tracking measurement principle of precision of laser tracker 5 self, the putting position limitation of laser tracker 5 is little, and the distance of distance can not influence measuring accuracy between laser tracker 5 and the target 6.
In the range ability of coordinate measuring machine, choose several measurement points through control system 2, and calculate the optimum operation path, the quantity of measurement point is many more, and demarcation and error of calculation value are accurate more, and 200 measurement points generally can be set.After fixing and starting laser tracker 5, the light direction of adjustment laser tracker 5 makes laser beam irradiation to the target that is positioned at initial position 6, and the distance value between record laser tracker 5 this moment and the target 6 and the angle value of laser beam light direction.Start coordinate measuring machine; The 2 predefined path operations of main frame 1 installation and control system, when target 6 moved between measurement point, laser tracker 5 was followed the tracks of target 6 all the time; Target 6 rotates automatically, and guaranteeing can be with laser beam reflected back laser tracker 5 when diverse location.Every measurement point, laser tracker 5 all can measure and recording laser tracker 5 and target 6 between distance value and the angle value of laser-beam deflection, and calculate two distance values between the measurement point, draw a data set b1.Because the coordinate parameters of measurement point is to utilize the cad model of coordinate measuring machine self to set; So control system 2 can calculate the distance value of setting between each measurement point; Draw another one data set a1, data set a1 just draws when setting measurement point in fact.With two groups of data input computing machines 3; Computing machine 3 just can go out the difference between setpoint distance value and the measuring distance value through computed in software; And draw the trueness error value of coordinate measuring machine; The accuracy compensation value that computing machine 3 draws according to Chebyshev polynomials principle analysis-by-synthesis, and feed back to control system 2 and compensate.
The disposable completion of whole calibrating and measuring process, and laser tracker 5 follows target 6 all the time automatically, need not shut down adjustment midway, guaranteed the continuity and the accuracy of measurement data.And than laser interferometer, laser tracker 5 receives Effect of Environmental such as temperature little, and it is more accurate to measure the gained data.Adopt the method that coordinate measuring machine is carried out accuracy compensation, accuracy and efficient all improve greatly.
For obtaining more comprehensively data, after measuring one group of data, first adapter rod 7 is pulled down, second adapter rod that changes the outfit, second adapter rod is different with the length of first adapter rod 7.According to the above-mentioned steps duplicate measurements once; Because the length of adapter rod changes; Be equivalent to all measurement points simultaneously to some direction translations same distance; Laser tracker 5 combines to calculate the measurement vector value between each measurement point according to these data that measure with data set b1, draw data set b2.Control system 2 calculates the setting vector value of each measurement point, draws data set a2.Data set a2 and data set b2 input computing machine 3 is compared, get final product outgoing vector accuracy compensation value, feed back to control system 2.The length difference of first adapter rod 7 and second adapter rod is big more, and the vectorial accuracy compensation value that draws is accurate more.Vector accuracy compensation value can reflect the precision level of coordinate measuring machine more comprehensively, more accurately, thereby more accurately coordinate measuring machine is carried out accuracy compensation and correction.