ment. After successful simulation, the operation program was implemented on the welding robot. The first step was to test the programmed trajectory of the robot’s movements without welding and to eliminate potential collisions. Testing of the operation program was repeated until the desired result was achieved. The program should ensure that the frame is welded without any errors in the weld joints and as quickly and simply as possible. To tune the proposed program successfully, testing a sample of 25 frames was necessary. Results The time needed for welding a frame was measured following implementation of the program into the production process. When the time measurement was finished, the average welding time for the frame was calculated. This was added to other times needed for additional operations for lifting fork production. After implementation of the robot into the production process, the time required for welding the lifting forks was approximately 100 min (1 h 40 min). The initial and actual production times for lifting forks are given in Table 4, where the SMAW time is compared with the time when the welding robot was used. Comparison with the initial frame production times showed an overall time reduction of 53% (106.5 min). Associate times took approximately 10% of the total production time. A finished frame is shown in Fig. 6. The manufacturing costs associated with production of the frame for lifting forks is proprietary information of KOVACO. Conclusions The experiment described in this article was conducted in cooperation with KOVACO, spol. s.r.o., Veľká Lehota, Slovakia, with the aim to reduce the overall time for producing lifting fork frames. In spite of repeated efforts, we failed to achieve the required precision for the parts, and therefore the original design drawing was redesigned. Simulation of the proposed program was followed by testing the program within the welding process in the robotized workplace in real time. To eliminate the deficiencies in the program, testing was accomplished on MARCH 2016 / WELDING JOURNAL 57 Fig. 4 — Technical drawing of the lifting fork frame after changing its construction. Fig. 5 — Simulation of welding the lifting fork frame. Table 4 — Comparison of the Initial and Actual Operations Results Time Name of Welding of Frame Manual Welding Time Savings Operation for Lifting Forks with of Frame for Lifting Forks (%) Welding Robot (min) (min) Alignment 36.5 90 60 Welding 58 110 47 Total 94.5 200 53
Welding Journal | March 2016
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