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Investigating the operating scenarios of a planetary strander through multi-body simulations

ㆍ Product: Planetary Stranding Machines

ㆍ Purpose of Analysis: Predict both maximum internal loads and the highest power demand

Planetary stranders are large machines used to produce steel strands and ropes in single- or multi-operation processes. These machines are designed to combine many stranding elements while twisting them around a common axis. The stranding elements are initially wound on reels, which are mounted on rotating cages. The extraordinary moving masses and the risks that would result from a structural failure are critical issues in the design of stranders. Mario Frigerio S.p.A., Italy, which is a leading manufacturer of stranders, was asked to develop customized planetary stranders that had to meet exceptional specifications. RecurDyn software was used to virtually analyze all the possible operating scenarios. Simulation results provided both the maximum loads for parts, sizing and, at the same time, the required information for choosing the huge electric motor powering the machine.

Process

① Imported the CAD geometry which included about 100 bodies. Bodies were connected using many types of kinematical joints.

② Friction on rotating shafts was considered.

③ Parameterized spools were built internally to reproduce different loading conditions (i.e. different types of ropes that the machine can produce).

④ All planetary gear units were modeled through the coupler entities.

⑤ 64 load cases were considered, focusing on 3 working phases: acceleration, constant speed, and emergency braking.

Key Technologies for Analysis

• Kinematic joints with friction

• Parameterized geometries for reels

• Coupler constraints for gear couplings

• Batch simulation of multiple operating scenarios

Toolkits

• RecurDyn/Professional

Customer Challenges

• Wide range of difficult-to-predict operating conditions specific to the customer’s needs

• Extreme dynamics due to the unbalanced reels rotating at relatively high speeds

• Identifying the optimal motor capacity

- If too small, the machine to not work in some operating conditions

- If too large, it would increase the total cost with no benefits.

Solutions

• Professional multibody simulation can quickly calculate the power peaks in dynamic conditions.
• Parameterized geometries allow for fast change of working scenarios.
• Calculation of the inertial loads and reaction torques is automatic.

Planetary Stranding Machine Reaction torques and forces on planetary gear units

Outcomes

• The maximum (sizing) loads acting on each machine component were obtained for proper structural verification.
• The crucial information required to choose appropriate electric motors was obtained by processing the simulation results from multiple load cases.

Other Applications

• Improving the capacity of a coffee capsule machine using multi-body simulation
  • Verification of the motion laws for the design improvement
  • Simplifying the structure of the main frame using simulation
• Virtual prototyping of sheet metal processing machine to improve capacity and precision
  • Reproduction of the dynamic behavior of the sheet metal processing machine
  • Improvement of the design of the machine control systems
  • Accurate prediction of the vibration of the system, required stiffness or thickness