FEATURE MACHINE BUILDING, FRAMEWORKS & SAFETY Constructing low vibration tools
A manufacturer of construction equipment is using Siemens Digital Industries software solutions to enhance product durability and quality, reducing vibration levels and enabling their permissible daily use to increase by 300%
W
hen building new products, designers may need to seek ways in which to reduce
vibrations as much as possible to meet health and safety requirements. Established in 1941, Hilti develops and manufactures construction equipment for use worldwide. Its TE 3000- AVR, for example, is its most powerful concrete demolition hammer. Featuring low vibrations and a brushless motor, this is designed to offer impressive hammering impact energy for rapidly demolishing large concrete structures. Not only is this capable of an exceptionally
high breaking performance – up to six tons of concrete per hour – but it is versatile, and is easy to operate and transport. The hammer also features active vibration reduction (AVR), which makes the tool less tiring to use.
MEETING STANDARDS To preserve the health of operators, tools need to be certified according to relevant international standards. So, to meet requirements, Hilti relies on the human body vibration filter add-in in Simcenter Testlab software, a powerful certification tool for analysing vibrations transmitted to the human body. The application gives real-time feedback and clearly indicates limit values and/or violations as specified in the International Organization for Standardization (ISO) 2631, ISO 5349 and the European Normalization (EN) 60745 standards. The AVR functionality used by Hilti allows
operators to be less exposed to vibration, thus increasing permissible daily use of the tool. For example, a large hammer drill without any anti-vibration measures has a vibration level between 20 and 30m/s². This means workers can use them for no longer than 30 minutes per day. The development of efficient vibration reduction technologies combined with extensive testing allows the user to reduce this level to below 10m/s², thus increasing permitted use time to two hours per day – a 300% increase. Prior to the certification process, Hilti products
undergo a series of comprehensive tests which help to shorten the product development cycle and answer market demand for longer product lifetime, enhanced reliability, high performance and low weight. At the Hilti Competence Center for Health &
Safety Technologies, group manager Lars Melzer and his team are tasked with challenging the performance of new tools: “There are two ways of qualifying new developments, the full system tests and the component tests,” he
14 APRIL 2020 | DESIGN SOLUTIONS
said. “We make use of the testing hardware and software in the Simcenter portfolio to perform these tests in an efficient and reliable manner.” In a system test, a complete functional
power tool is tested according to its real-life applications. The test procedure reproduces simplified load cases collected on artificial work pieces. On the other hand, a component test focuses on a single component, such as a switch, electronic assembly, battery interface, motor, etc., which is isolated from the power tool. Component tests are performed on specific test rigs or a shaker (see image, below).
Images courtesy of Hilti Deutschland AG
capabilities available in Simcenter Testlab: impact testing, operational deflection shapes (ODS), experimental modal analysis (EMA) and operational modal analysis (OMA). These allow the Hilti team to identify potential damages and plan the mounting conditions of the device under test (DUT) or the test specimen on the shaker. Following this, the team performs vibration
measurements using Simcenter Testlab Signature Acquisition and Spectral Testing for defining and executing several tests corresponding to various applications and load cases. Simcenter SCADAS is used to acquire data that generates representative shaker profiles. The selected parameters for the load cases consist of a combination of tool, user, workpiece, insert (such as drill bit) and feed force.
UNDERSTANDING VIBRATION BEHAVIOUR Component tests require shorter amounts of time, are less costly and can be executed even before the first prototype or tool is available. To ensure the product’s high quality, reliability and efficiency, shaker tests require a clear process. It begins with acquiring data using Simcenter
SCADAS hardware and Simcenter Testlab Spectral Testing software. The Hilti engineers perform an analysis on the data, using the Simcenter Testlab Signature acquisition capabilities to better understand the component’s vibration behaviour. Simcenter Testlab Impact Testing helps the team perform accurate shaker test setup. Simcenter Testlab Mission Synthesis is used throughout the shaker tests and validation. Finally, at the end of the process, the data is stored, managed and shared in an interactive graphical manner with the Simcenter Testlab Desktop application. Matthias Patalong, development engineer
on Melzer’s team, said: “Simcenter helps us set up quick and reliable component tests with minimal effort. All necessary functions are integrated within one software solution, making data conversion unnecessary.” To get an understanding of the dynamic
behaviour of the system in the first phase, the team relies on the structural testing and analysis
DESIGNING THE FIXTURE For excellent fixture design, Hilti relies on tools from the Siemens Digital Industries Software portfolio, including the computer-aided design (CAD) module in NX software, as well as numerical analysis and physical testing tools from the Simcenter portfolio. The process starts with designing the fixture
using NX CAD. Then, performing a numerical modal analysis using Simcenter 3D is only a step away. The fixture design is iterative and done in active collaboration between the design and simulation teams; and the Siemens software suite supports effective communication between the different teams. Once the fixture is manufactured, the team
performs the required physical tests and analyses to validate its design: experimental modal analysis and ODS analysis. Once the fixture is validated, the physical component test is executed. The test item and its fixture are placed on the shaker and instrumented. The testing team feeds the defined test signal to the shaker, determines the frequency limit for the test and adapts the signals if required. One of the main benefits of performing shaker
component tests is that other conditions can be assessed simultaneously with the vibration tests.
Siemens Digital Industries
www.sw.siemens.com
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