New Zwick high-precision spring-testing instrument

The increasing use of powerful miniaturized mechanical and electromechanical units is influencing product development in many sectors, including the automobile industry and medical technology. Springs used for these applications are also becoming ever smaller, but must still deliver precision and reliability, placing greater demands on testing technology. To meet this challenge, Zwick has developed a new high-precision spring-testing instrument featuring fast, easy operation. This hand-operated spring tester records spring compression stress-strain characteristics in full, with no need to stop at the measuring points. Load and deflection are recorded synchronously.

Intensive development work has created a concept which guarantees highly accurate test results. One important factor in this is mechanical compensation of load cell deformation, ensuring maximum precision in deflection measurement under load (resolution 0.12 µm). The reference line of the deflection measuring system lies along the same axis as the spring length being measured. That practically eliminates the length measurement error.

Other important factors in providing highly accurate measurement are the extremely stiff load frame and load application aligned to the specimen centerline, resulting in minimal elasticity through the entire test arrangement.

Integrated mechanical overload protection of the load cell provides reliable damage prevention, avoiding tester downtime and load cell replacement and calibration costs.

The machine possesses three adjustable mechanical limit switch stops for starting position, pre-stress length and minimum permissible test length.

The new spring tester is suitable for production line use and in design and development, while standard interfaces enable connection of additional measuring equipment such as dimensional measuring devices.

The addition of the proven testXpert® II testing software to the manually-operated spring tester produces an ideal package for testing small springs and ensures simple, quick, safe and reliable testing.

The testXpert® II Test Program is ideally adapted to the requirements of spring testing. Contents include integrated histogram and statistics functions, pre-defined specific results, online graph and test result recording plus optional Statistical Process Control (SPC) functions, while flexible, efficient interfaces allow testXpert® II to communicate with an organization's IT infrastructure.

Zwick Roell Group in profile
Zwick Roell Group customers benefit from more than 150 years of experience in the manufacturing of high quality testing systems.  Zwick is the global leader in static testing and is experiencing significant growth with its dynamic test systems.  A financially strong and family run business, its innovative product developments, diverse product range, and global support provide tailored solutions targeted specifically at the needs of both Research and Development and Quality Assurance customers.  Serving more than 20 industry sectors with 960 employees, via manufacturing facilities in Germany, regional headquarters in Atlanta, Georgia, USA and Singapore, as well as offices in 56 countries worldwide, the brand name Zwick is a guarantee of the highest quality and support.

For further information, view website: www.zwick.com   Refer to page 50

The Moog servomotor-driven servo-proportional valve

Moog's Industrial Group, a division of Moog Inc. (NYSE: MOG.A), designs and manufactures high performance motion control solutions combining electric, hydraulic and hybrid technologies. The company is a leader in providing high performance motion control to the industrial market. Today, Moog announced a new actuation concept that makes its Servomotor-driven Servo-Proportional Valves exceed current performances.

Although hydraulic servo- and proportional valves currently available on the market have supported numerous applications in a variety of industries for years, some applications didn't further develop. They lacked a valve that could perform to their specific requirements. Moog has developed an actuation concept that enables the Servomotor-driven Servo-Proportional Valve to reach an unprecedented level of dynamics combining very high flow and high frequency bandwidth. It is particularly recommended for high performance applications such as test systems, die casting machinery and steel production.

With more than half a century of experience designing, manufacturing, and supporting hydraulic technology and a few decades of experience with electric solutions, Moog is globally recognised as a motion control expert. As customers keep increasing technology expectations, Moog continues to respond to difficult motion control challenges with designs and products that meet customer expectations and help them push the boundaries of their own applications.

"This is a great opportunity for us to demonstrate our expertise in applying a new concept to existing technology in a way that matches the needs of our industrial customers. Applications such as testing, and die casting using high frequencies and high amplitudes can now reach the higher dynamics they require to perform. High frequency, flow rates and pressure levels can now be combined as never before, opening up new actuation possibilities. We look forward to developing the new valve more extensively with our customers to create new applications based on dynamic closed-loop pressure or force and acceleration control. We can reach impressive dynamic characteristics such as a step response time of 2.5 ms, a phase lag of 45 degree at 150 Hz and +/- 90% amplitude with a maximum flow of 600l/min.

The innovative concept is based on an optimized Moog Servo motor directly actuating the valve spool. This integrated design ensures that the valve response is independent from the supply and control pressure so it optimizes energy and offers high dynamics with a minimum heat," said Sherif El Henaoui, Marketing Manager Europe, Moog. For further information view website: www.moog.com/industrial

University of Sheffield extends collaboration with Moog to
create configurations of complex control loops using advanced
features required for bi-axial testing on material stress and fatigue loads

Moog Industrial Group, a division of Moog Inc. (NYSE: MOG.A and MOG.B) and a leader in providing leading-edge solutions and products for the test industry, has completed the latest upgrade to a Mayes biaxial tension/compression test machine for the University of Sheffield. 

The system upgrade for the University of Sheffield included of a complete overhaul of the machine and integrating a new control system. The bi-axial machine uses a traditional cruciform specimen for testing various materials; such as steel, composites and aluminium used in applications such as nuclear waste disposal, airframe testing, and measuring friction and stress loads in landing gear. A team from Moog's facility based in Solihull, United Kingdom, which specializes in Test and Simulation, completed this upgrade that included the installation and calibration of the machine as well as training of the University staff. The University of Sheffield has seven portable test controllers in operation and a further system has since been ordered from Moog.

The test machine upgrade from Moog incorporates a four channel Moog Portable Test Controller.

The test machine upgrade incorporated a four channel Moog Portable Test Controller. Stuart Bibb, Manager Test Systems, said, "The complex control loops required for this customers' test were configured using the advanced features and tools provided by the Moog systems. This is the kind of flexibility and support which makes the Moog Portable Test Controller stand out from the competition." 

Bi-Axial testing is notoriously complex because the specimen has to be held in the absolute centre of the machine, so that the specimen loading is perfectly symmetrical. This means that the system needs to be controlled in both displacement and force, to ensure that the specimen centroid is maintained. The Moog Portable Test Controller achieves this through the use of User Defined Channels and Pseudo Channels (calculation channels).

The Moog system features a host of functional upgrades including the ability to create virtual control channels that represent a defined force and translation through kinematic conversion. "Kinematic conversion makes it possible to provide a set point per DOF (Degrees of Freedom) so it becomes easier to create spectrum," said Bibb. 

"The test controller can synchronize different scenarios through multiple channels and create a virtual DOF. It provides engineers with greater flexibility to create movement and improved control of the test mechanism." 

The system allows engineers to configure the control loop and create feedback from the test specimen, on aspects such as average force and position. Additionally, it can create a sine wave concentrating on the end goal in less than one hour.

Mike Rennison, Experimental Officer, Department of Mechanical Engineering, University of Sheffield said: "We chose the Moog Portable Test Controller because it is much more versatile and flexible than others on the market, enabling us to push the boundaries further during testing. It has also enabled us to upgrade all our equipment to meet the challenges brought to us by our customers. Our experience with the Portable Test Controller has been highly successful and we are ordering additional equipment from Moog."

The Bi-axial machine at University of Sheffield is configured as shown in figure 2, the Moog Portable Test Controller is set up to have an additional four User Channels:- Force 1, Force 2, Translation 1 and Translation 2 in addition to the four hardware channels. 

Figure 1: Bi-axial machine configuration: The User Channels can then be used in the same manner as hardware channels to provide the facility to position the actuators for specimen mounting and apply the correct force distribution. The translation channels are used to keep the specimen location in the desired position and the force channels are used to apply the dynamic load to the specimen in perfect symmetry. 

Figure 1: Bi-axial machine configuration (right), Figure 2: Bi-axial Machine User Channel Configuration (left).

Using the Translation mode, Translation 1, for the 'y' axis and Translation 2, for the 'x' axis, the position of both actuators can be adjusted by using the setpoint command for that axis. This will maintain the distance between the two actuators, moving both the actuators simultaneously, and by the same amount.

Figure 2: Bi-axial Machine User Channel Configuration. The force channels are used to apply the dynamic load to the specimen, Force 1 for the 'y 'axis and Force 2 for the 'x' axis. The dynamic command signal can be applied to both axes simultaneously with a phase lag if required.

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