As a cornerstone of several manufacturing industries, machine tools carry a heavy responsibility for promoting industrial progress. The acceleration of scientific and technological innovation in today’s “intelligent era” has vastly elevated manufacturers’ expectations for machine tool performance. These new expectations encompass greater speed and precision, the traditional measures of machine-tool effectiveness, but also extend to automation, intelligence and other dimensions.
Challenge
In order to meet the market demand for high-efficiency, high-quality products, many machine tool OEMs have begun to explore new transmission technology and control systems in a bid to outperform the competition. For one major OEM, advancements in industrial automation and intelligent manufacturing have created a demand for significantly higher performance in its double-face grinding machines.
These machines process a wide range of shaped and round metal parts as well as nonmetallic thin parts, including bearings, valves, aluminum alloy plates, seals, oil pump blades, piston rings and more, by precisely removing material from two sides of the workpiece at the same time.
Confronted with increasingly stringent processing standards and stiff market competition, the OEM needed its machines to achieve greater dynamic performance and control accuracy along with higher feed and acceleration rates. At the same time, the pressure to improve machining efficiency and accelerate output was met by the need to reduce costs and ensure quality — key challenges that all had to be solved simultaneously.
Solution
Backed by more than 70 years of experience in motion control technology, Kollmorgen has launched a solution consisting of IC Ironcore DDL linear servo motors with AKD servo drives to address the development needs of the machine tool industry, including the demanding requirements of double-face grinding machine applications.
Available for supply voltages as high as 480 VAC, the IC Ironcore DDL linear motor can deliver a continuous force range up to 8,211 N and peak force up to 13,448 N. In this OEM’s application, it achieves a material-removal capability of more than 1 mm in less than 1 second cycle time, with the workpiece processed to an average tolerance of ±0.002 mm. With the high-performance control loop and high-bandwidth response of the AKD servo drive, the speed variance of the slicing and feeding mechanism can be controlled precisely, ensuring precise results at the requisite high speeds.
In this particular application, the IC Ironcore DDL motor responsible for slice feeding reaches a peak thrust of 3,152 N, enabling the 2.5 g acceleration required to achieve the OEM’s target processing speed. The speed command, position command, filtering and delay functions of the AKD servo drive effectively ensure rigidity of motion while minimizing any overshoot, greatly improving the stability of the equipment and providing an assured yield rate.
Results
Compared to the transmission-driven solution that was previously used, Kollmorgen’s direct drive linear solution achieved a 65% improvement in positioning accuracy, 66% increase in acceleration and 75% improvement in control of velocity ripple. These enhancements increased production speed by 15%, setting a new standard for double-face grinding machines in the era of batch customization. At the same time, the simplified direct drive structure dramatically reduced maintenance costs while lowering energy consumption by approximately 20%.
“The combination of Kollmorgen’s DDL linear motors and AKD servo drives breaks through the old technological boundaries of the machine-tool industry. Kollmorgen is helping build a bridge from traditional processes to a future manufacturing model with endless possibilities.” —Double face grinding machine manufacturer
