Shenyang Machine Tool Corporate, Limited (SMTCL) was founded in 1995 and is a state-owned company in China. SMTCL offers a variety of products, including conventional lathes, CNC lathes, pipe threading lathes and milling and boring machining centers. Their products are used in industries such as automotive, aerospace and defense, and railway transportation.
Today’s competitive environment and the demand for energy efficiency compel industrial machinery manufacturers to develop innovative products that provide maximum performance and minimum operational cost and downtime. Customers require machines that deliver optimal throughput and comply with ever-stricter standards and regulations. Apart from the environmental aspect, this also applies to safety and reliability. This strongly relates to the overall noise and vibration behavior of the design, as strong vibrations can lead to structural damage and potentially even life-threatening situations.
All of this makes designing machines a complex task of balancing conflicting requirements. Speed and precision call for high-velocity, synchronized movement of many interconnected parts. However, the resulting amplified internal force peaks may negatively impact consistent production quality, fatigue resistance and radiated noise. Customers want weight reduction for lower material and logistical costs but still expect the same overall quality. The increased use of controls and intelligent electronic systems helps to deliver optimal performance, yet adds to the design complexity.
“Machine tool technology has evolved dra-matically,” says Zhao Feng, a design engi-neer in research and development (R&D) at Shenyang Machine Tool Corporate Limited (SMTCL), a Chinese state-owned manufacturer. “Compared to earlier days, customers give us more and more bound-ary conditions. They need precision, performance and ease-of-use, but they also must meet new and stricter regula-tions. For the health of the operators, we have to reduce the noise as much as possible, for example. We have to consider so many aspects that a structured and efficient development approach is required.”
Analyzing and refining the machine structure used to be a long process of trial-and-error on expensive physical prototypes, but tight schedules and budgets no longer allow for this approach. Machine manufacturers are looking into various simulation technologies that can help them make the right decisions in the early design stages and deliver higher product quality on the first attempt. This considerably reduces the total development cycle, saving time and money.
The SMTCL engineers found that Simcenter™ solutions from product life-cycle management (PLM) specialist Siemens provide the most complete environment that covers the entire process. By aligning multidomain system simulation, detailed 3D analysis, and test-based engineering in a streamlined development process from concept modeling to physical prototype evaluation, Simcenter solutions help bring innovative, high-quality and eco-friendly designs to market faster than the competition. They enable industrial machinery manufacturers such as SMTCL to deal with the growing technological challenges and increasingly complex customer requirements that come with Industry 4.0.“
By shortening the development time, our products can go to the market earlier, which makes us a technical guide and innovation pioneer,” says Feng. “Simcenter solutions from Siemens provide us with all the necessary tools to optimize reliability and stability in a shorter time. This improves the quality of our products and helps us to build brand value. Moreover, the combination of these tools with Siemens’ computer numerical control (CNC) systems and motor drive systems delivers a complete, integrated solution to build our machines.”
In the first project, the SMTCL engineers successfully validated Simcenter 3D simulation software on the structure of a CNC vertical lathe. While developing that machine, which is especially suitable for difficult-to-cut materials such as ceramics, it was Toolparticularly important to reduce vibration in order to guarantee smooth operation. The engineers analyzed the system’s eigen-frequencies using Simcenter™ Samcef™ software and compared the outcome with modal test results that were obtained with Simcenter SCADAS™ hard-ware and Simcenter™ Testlab™ software.
“Simcenter Samcef combines advanced finite element analysis with multibody simulation in a very unique way,” says Feng. “Thanks to the available features, we can couple the individual machine components, both rigid and flexible, during simulation. The software has very powerful solvers that include capabilities for parallel computation and relies on world-class technology, especially for nonlinear analysis and large deformations. During the first validation, the difference between calculated and measured natural frequencies was lower than 16 percent, which proved the reliability of the flexible parts modeling.”
The modal analysis results already indicated some ways to improve.
“We found rather large modal deformations on the spindle box and the body box in the first eigenmode,” says Feng. “As a result, the main shaft and the working table were relatively displaced, which was bad for the machines’ functioning. That alerted us to the weak connection stiffness between the main shaft box and the body box, and between the body box and the column. We could also conclude that the main shaft box structure had to be reinforced for a better stiffness balance.”
After this successful model validation, the SMTCL engineers further detailed the connections for full nonlinear mechanism dynamic analysis. Between all the flexible components, relations were defined that helped accurately simulate hinges, screws, prismatic connections, constraints and much more. This allows SMTCL engineers to predict dynamic stress on machine components in operation. In this way, the rail, slider, screw, lathe bed, column and body box can be evaluated for various load conditions. This method helped SMTCL uncover potential risks in the early design stages, thus proving its value and becoming a standard part of any future SMTCL machine tool development.
Intense collaboration with Siemens experts helped the SMTCL engineers get up-to-speed quickly with the new package. Thanks to a joint project and dedicated training, Simcenter Samcef was easily adopted.
“We also evaluated other software with similar nonlinear capabilities,” says Feng. “But Simcenter Samcef nonlinear has more efficient capabilities for building the mechanism model. For this reason, it is the better option to build models for machine tools, robots and so on. That was clearly demonstrated by the experts from Siemens during the evaluation.”
This efficiency helps SMTCL reduce development time. “Having this all-in-one solution avoids the need for cumbersome file transfer between the different soft-ware packages that was part of our previous simulation process,” says Feng. “Thanks to Simcenter solutions, we can complete all simulations for a component in about two days. Previously, the same process could take up to five days. We can say that Simcenter Samcef allows us to reduce the time we spend for simulation during development by over 50 percent. And, on top of that, it is more accurate.”
SMTCL engineers want to further deploy Simcenter Samcef in future projects. They even plan to take it to the next level. Another reason they decided to select Simcenter solutions is that these include capabilities for coupling the mechanical system with electronics and controls using Simcenter Amesim™ software.
“This will be the next challenge,” says Feng. “We want to offer our customers a better user experience. Intelligent manufacturing is really the future of our business. By combining the high-end, nonlinear mechanical solution Simcenter Samcef with the electrical simulation in Simcenter Amesim and controls technology, we have all the components in place to help us develop the next-generation machines.”