Elimination of errors in the large screw heat bilges cold shrink

Elimination of errors in the large screw heat bilges cold shrink - 2019 11 - 30 in many large, high precision automation machinery, extensive use of ball screw with linear guide rail mobile platform deck or agency ( FIG. 1) And large heat bilges cold shrink of the existence of ball screw, could reach 200 & mu; M above the error. For the similar TFF - LCD industry, and precision of semiconductor manufacturing industry is not acceptable, especially in the imaging system to automatically locate the machine by the cold machine to heat engine in the process of transformation, the error generated by the heat bilges cold shrink phenomenon caused by the dislocation, migration and so on will seriously affect the product precision and quality. Use KEYENCE LB - 70 series laser displacement sensor for real-time detection of the ball screw heat bilges cold shrink variation, the compensation value of feedback to PLC, through compensation calculation takes into account the change quantity, so as to realize the zero error of ball screw. A, ball screw thermal cold drop-off analysis for the larger ball screw is considering the problem of heat bilges cold shrink, THK, chronic kidney disease (CKD), etc. Series screw, for example, generally USES fixed at one end, Connect the motor end) And the other end of the retractable way. Therefore, mobile load motor in screw near the proximal and distal the impact is not the same. Proximal cumulative changes in the quantity is small, also had little impact on the precision of the products and the remote changes due to the expansion of the accumulated throughout the screw, so had a great influence on the accuracy of product ( FIG. 2) 。 Second, the LB - The 70 series laser displacement sensor 1. Laser displacement sensor KEYENCE LB - The 70 series laser displacement sensor has 2 & mu; M high resolution, 0. 15 ms rapid response time, precisely to 0 v set, and can be long distance measurement. Figure 3 a and LB - for the laser controller The appearance of 11 laser head figure. Figure 4 LB - 11 laser head of zero adjustment range and linear range. Other details visible KEYENCE sensor manual and set operation method. 2. After the detection principle is set to 0 v potential, through from the sensor head of laser detection target distance changes into a dc voltage output, then the PLC module, add a piece of analog-to-digital conversion module, thus the real-time voltage changes into a distance. Three, improvement scheme 1. Setting method to sensor head fixed in the machine fixed seat ( Motor side) , reflective piece as the target to the mobile stage monitoring expansion volume change ( FIG. 5) 。 In L1 ( 0mm< l1< 100mm) Place set displacement testing point P1 ( Try to select load in the process of production need to move to the point, avoid increasing cycle time) , in the condition of cold machine adjust output voltage to 0 v ( No expansion amount change) , PLC control in the process of normal production when mobile to P1 point for data collection, record the P1 point expansion of S1, can according to the formula ( 1) The quantity of the expansion of the other displacement point conversion of Sn. S will swell. Through the various of PLC in relationship to the displacement ( Compensation calculated) , can be a variety of temperature and quantity of the expansion of the spot to eliminate the influence of product precision. Figure 6 to show the real-time detection of expansion value in man-machine interface. This plan has been in TFT - LCD manufacturing industry get success in practice, the effect is very good.