Integration of Machining and Measuring Processes Using On-Machine Measurement Technology

This paper presents an integration methodology for ma chining and measuring processes using OMM (On-Machine Measurement) technology b ased on CAD/CAM/CAI integration concept. OMM uses a CNC machining center as a me asuring station by changing the tools into measuring probes such as touch-type, laser and vision. Although the measurement accuracy is not good compared to tha t of the CMM (Coordinate Measuring Machine), there are distinctive advantages us ing OMM in real situation. In this paper, two topics are handled to show the eff ectiveness of the machining and measuring process integration: (1) inspection pl anning strategy for sculptured surface machining and (2) tool path compensation for profile milling process. For the first topic, as a first step, effective mea suring point locations are determined to obtain optimum results for given sampli ng numbers. Two measuring point selection methods are suggested based on the CAD /CAM/CAI integration concept: (1) by the prediction of cutting errors and (2) by considering cutter contact points to avoid the measurement errors caused by cus ps. As a next step, the TSP (Traveling Salesman Problem) algorithm is applied to minimize the probe moving distance. Appropriate simulations and experiments are performed to verify the proposed inspection planning strategy, and the results are analyzed. For the second topic, a methodology for profile milling error comp ensation is presented by using an ANN (Artificial Neural Network) model trained by the inspection database of OMM system. First, geometric and thermal errors of the machining center are compensated using a closed-loop configuration for the improvement of machining and inspection accuracy. The probing errors are also t aken into account. Then, a specimen workpiece is machined and then the machi ning surface error distribution is measured on the machine using touch-type pro be. In order to efficiently analyze the machining errors, two characteristic err or parameters (W err and D err) are defined. Subsequently, these param eters are modeled by applying the RFB (Radial Basis Function) network approach a s an ANN model. Based on the RBF network model, the tool paths are compensated i n order to effectively reduce the errors by employing an iterative algorithm. In order to validate the approaches proposed in this paper, a concrete case of the machining process is taken into account and about 90% of machining error reduction is successfully accomplished through the proposed approaches.

Therapeutic efficacy observation on moxibustion with moxa of different storage years for moderate-to-severe primary knee osteoarthritis

Objective:By observing the differences in Western Ontario and McMaster Universities osteoarthritis index(WOMAC)and visual analog scale(VAS)scores in moxibustion treatment for moderate-to-severe primary knee osteoarthritis(KOA)with moxa of different storage years(3-year moxa and 1-year moxa from Qichun,Huanggang City,Hubei Province,China)through a randomized clinical trial,to objectively evaluate the differences in therapeutic efficacy of moxibustion with moxa of different storage years.Methods:A total of 63 patients with moderate-to-severe KOA who met the inclusion criteria were randomized into moxibustion group 1 and moxibustion group 2 by central randomization method,with 32 cases in moxibustion group 1 and 31 cases in moxibustion group 2.Moxibustion group 1 was treated with moxa stored for 3 years,and moxibustion group 2 was treated with moxa stored for 1 year.Dubi(ST 35),Neixiyan(EX-LE 4)and Heding(EX-LE 2)were selected in both groups,and the treatment lasted 20 min per time,3 times a week.The immediate efficacy was compared after 6 times of treatment,and long-term efficacy was compared at follow-up 4 weeks after the end of treatment.Results:During the treatment,there were 2 dropouts in moxibustion group 1,and 1 dropout in moxibustion group 2.The total effective rate in the two groups was 83.3%and 60.0%,respectively.Followed up at 4 weeks after the end of treatment,the total effective rate in the two groups was 80.0%and 66.7%,respectively.There were no statistical differences between the two groups(both P>0.05).After treatment and 4 weeks after the end of treatment,the WOMAC and VAS scores in both groups decreased significantly compared with those before treatment(all P<0.01);the scores of stiffness item of WOMAC in moxibustion group 1 were lower than those in moxibustion group 2(both P<0.05);there were no statistical differences in the scores of pain item and dysfunction item of WOMAC,and VAS scores between the two groups(all P>0.05).Conclusion:Moxibustion with moxa of different storage years(stored for 3 years and 1 year)both can improve the pain,stiffness and motor function in patients with moderate-to-severe KOA.While moxa stored for 3 years has a better therapeutic efficacy in improving stiffness of the knee joint than that stored for 1 year.