2 years ago

MDA Technologies 1/2015

MDA Technologies 1/2015

Custom motors with high

Custom motors with high power density for robot all-rounders Thorsten Sienk Kuka’s compact robots in the KR Agilus series are agile systems that feature short cycle times and high repeatability, particularly for pick-and-place tasks. Synchronous servo motors from Kollmorgen play a major role in achieving this high precision. Using collaborative co-engineering, the two companies were able to create several benefits for end users. Author: Thorsten Sienk is a freelance technical journalist for Kollmorgen in Ratingen, Germany The performance of the KR Agilus series within its rated load range sets new standards for speed, cycle times and energy supply. They can even handle unusual tasks in base and cover installation positions. Kollmorgen developed the custom motors by adapting motors from the standard AKM servo motor series without compromising performance or quality. Custom motors with high power density As fast all-rounders, the robots in the KR Agilus series are particularly suitable for general industrial applications. With a deadweight of 51 kg, the basic model can support loads up to 6 kg. The compact robots are therefore ideal for process automation in the packaging, electronics, food and pharmaceutical industries. “We made a significant contribution to short cycle times and high precision by adapting our servo motors from the AKM series to Kuka’s spe- cific needs”, says Theo Loy, Sales Manager at Kollmorgen. The co-engineering partner adapted the design of the synchronous servo motors to make them fit perfectly in the joints of the KR Agilus robots. “That also enabled us to increase the already high power density.” Looking back on the start of the partnership, Loy comments: “As part of the development project for their new compact robots, Kuka was looking for a motor manufacturer that could supply custom motors with very high power density. The torque to volume ratio turned out to be the decisive factor that got us into the picture. The AKM servo motors are simply unbeatable.” The project quickly evolved in the direction of collaborative co-engineering. The objective was to find ways to implement custom performance improvements and structural assembly adaptations without sacrificing the advantages of industrial series production. “Although Kuka’s requirements could not be met with off-theshelf motors, we did not want to launch a 28 MDA Technologies 1/2015

DRIVE TECHNOLOGIES 01 02 01 The package size of the motors was reduced significantly for the project 02 The compact robots are particularly suitable for handling tasks like pick-and-place operations full-scale development project with all the associated risks.” Instead, the aim was to optimize standard motors by making controlled modifications. “Standardization, availability and quality are crucial.” With custom adaptations such as cable strain reliefs, modified bearing shells, Kukaspecific connector configurations or special drilled holes in the output shaft, the motor manufacturer could reliably maintain the majority of its standardization, but is that still possible when the entire design geometry is fundamentally changed? The co-engineering process That was exactly what happened with the smallest servo motor in Kollmorgen’s AKM series. Already very small from the start, it had to be made even thinner to fit compactly into the wrist joint of the robot. The co-engineering process started off with 3D models and outside contours, and in the end it involved working with detailed design data. Now only the internals of the AKM1 motor in the KR Agilus robot are the same as its counterpart in the standard product line. In addition, the drive systems and motion control specialist manufactures the motors for the Augsburg-based robot foundry in optimized production cells with custom test processes and quality control procedures, as well as specific packaging for transporting the motors directly from the assembly line to Kuka. To round out the quality management picture, Kollmorgen’s branch in Bruno (Czech Republic) conducted a failure modes and effects analysis (FMEA) for the two coordinated processes. To make things easier for the customer in the project, Kollmorgen also incorporated the engineering expertise of its own suppliers, such as a specially adapted motor brake. “It acts as both a holding brake and an emergency brake”, notes Loy, with an eye to the fact that the KR Agilus is the only robot in its class that features Kuka’s own Safe Operation functionality. That drastically simplifies human-robot interaction. 500,000 different motor configurations The AKM series of high-acceleration permanent-magnet servo motors are available in 28 housing and mounting combinations to facilitate compact machine designs. They also feature reduced energy consumption, extremely high control accuracy and very high availability, and they are compatible with all commonly used supply voltages thanks to specifically adapted stator windings. For truly individual configuration of the synchronous servo motors, Kollmorgen offers a modular range of sizes and power ratings along with other special options. As a result, more than 500,000 different permanent magnet motor configurations are possible within the series using proven standard components. This is further enhanced by the connection system with only one cable between the motor and the controller. The advantages of single-cable connection between servo motors and their controllers extend over the entire value chain in the mechanical engineering sector. Physical transmission of the encoder signal from the AKM motor over the motor cable eliminates an interface. This yields concrete savings by dispensing with a cable and two connectors, which in turn reduces installation time and space requirements for the cabling. About Company name: Kollmorgen Established: 1916 Headquarters: Radford, VA, USA Revenue: $ 500 m Employees: ca. 2,000 worldwide Products: servo motors, automation platforms, linear actuators, drives, controls, … MDA Technologies 1/2015 29


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