mayr® power transmission's ROBA®-topstop, a modular construction brake Type series, with individual brakes

If there is a danger of falling loads on vertical axes in areas where personnel have to work, additional measures must be taken to minimise the risk of accidents. The Mauerstetten brake specialist mayr® power transmission has developed brake systems which are capable of providing safety in any critical situation occurring during vertical axes operation.

Vertically-moved masses, in particular when they are heavy parts such as motors or gear boxes, become a serious safety hazard if, on power failure, their movement is inadvertently accelerated or if they drop uncontrollably.

mayr® power transmission offers the ROBA®-topstop, a modular construction brake Type series with individual brakes and redundant dual-circuit brake modules for the prevention of any critical danger situations which can occur during vertical axes operation and which are defined in the DIN EN 954-1, Categories 1-3.

mayr® power transmission offers the ROBA®-topstop, a modular construction brake Type series.

The aspect of safety was not the only target criterion during development of the ROBA®-topstop. The constructional conditions for drive elements in vertical axes were also considered carefully. Due to their adapted flange dimensions, ROBA®-topstop brakes can be integrated problem-free into pre-existing constructions between the servomotor and the counter flange. The modular assembly is flexible enough to allow many different designs, for example with a shaft; with a hollow shaft; with a flexible coupling; with an additional safety clutch for torque limiting or with two individual brakes.

Using a ROBA®-topstop brake system with a hollow shaft and an integrated, insertable shaft coupling means that the separate compensation coupling and the coupling housing usually necessary are no longer needed. A drive line with this brake system is only minimally longer than the usual axis with servomotor and shaft coupling for connection to a spindle or to a gearbox shaft. ROBA®-topstop designs with shafts are principally conceived for installation between the servomotor and the hollow shaft gearbox.

As an independent module, the ROBA®-topstop is capable of holding the vertical axis in any required position. Additional measures for axis support - for example during transport and machine maintenance - are unnecessary.

This advantage means considerable savings in terms of cost and time; for example when replacing the drive motor, and reduces the downtimes during repairs. In addition to this, the device can guarantee the «safe brake» function, if the units are equipped with the correct functional and wear monitoring systems.

Product lllustration: File: F-6-24-Bild1.jpg Due to their adapted flange dimensions, ROBA®-topstop brakes can be integrated problem-free in pre-existing constructions between the servomotor and the counter-flange.

For further information, e-mail: andrew@mayr.co.uk or view website: www.mayr.co.uk

ROBA®-linearstop: A safety brake
for dynamic linear-motion braking actions

Most of the brake elements available on the market today work purely as clamping units. They are only designed to secure the axes at a standstill, and are not suitable for dynamic braking procedures. The ROBA®-linearstop, however, is a fully adequate safety brake according to the Trade Association testing requirements. It enables reliable braking of axes in motion.

The dynamic safety brakes in the ROBA®-linearstop series work according to the fail-safe principle. The braking force is provided by pressure springs and transferred backlash-free via a conical surface onto a collet. This collet clamps the brake rod continuously, without changing its position. In closed position, the brake is able to withstand loads in both directions of motion. Dynamic braking actions can be achieved from speeds with a maximum of 2 m/s.

Figure: Safety brakes of the ROBA®-linearstop series are designed for dynamic braking applications and can be mounted directly onto standard cylinders according to DIN ISO 15552.

Dynamic stops were tested according to the Trade Association testing requirements on the mayr®-Drop Test Stand. In compliance with the Trade Association requirements, the tested elements are switched a million times statically and load-free, and a million times with load assumption. At every thousandth switching, they are braked dynamically from motion. The ROBA®-linearstop brake unit achieved 30,000 dynamic brake applications in fatigue tests with a maximum load and is therefore substantially better than the Trade Association testing requirement, which only stipulates 1,000 dynamic brake applications.

ROBA®-linearstop safety brakes can be mounted directly onto standard cylinders according to DIN ISO 15552. They can also be integrated simply, quickly and without complicated adjustment into different drive constellations. In contrast to other linear braking systems, the ROBA®-linearstop does not have to travel on the carriage. Supplying the pneumatic lines is therefore simplified. The brake can be screwed to a static machine component. The cylindrical piston rod is guided through the central bore of the brake and connected to the carriage of the linear drive.

As the carriage moves, this piston rod pushes itself axially through the ROBA®-linearstop. When the brake closes, the carriage is braked dynamically and then held backlash-free and accurately positioned. The axis is secured in both directions of motion. The brake is released pneumatically at 4 to 6 bar, according to the configured braking force. An integrated sensor continuously reports the switching status of the brake. The ROBA®-linearstop brake unit is supplied in four construction sizes with nominal retention forces of 1.5 kN up to 40 kN.

For further information, e-mail: andrew@mayr.co.uk or view website: www.mayr.co.uk

HMI - Build versus Buy

Any manufacturer of complex machines or vehicles that include HMIs must face a crucial decision: should you build your own human-machine interfaces or should you buy these vital components ready-made or customized from an outside source?

The build versus buy decision is both important and complex, involving many tough questions. Is developing the necessary hardware and software in-house the most cost-effective solution? Is such an engineering project consistent with your core competencies? Do your engineers have the time to develop these devices in house? Have you calculated the opportunity costs involved? Will a commercially available product line provide the features and operating reliability you require at a return on investment (ROI) you can afford?

A closer look
To help you solve the build versus buy dilemma, let us take a closer look at what is involved in designing, building, testing and maintaining a human machine interface system by outlining a typical product development cycle.

Planning
Begin by making an honest assessment of your engineering capabilities. Given your company´s core competencies and priorities as well as the opportunity costs involved. Is the design of a human-machine interface terminal the best use of precious engineering resources?

Design Phase
The first consideration in the engineering design phase is whether your engineers have the experience to design and build complex human-machine interface.

Next, consider that many aspects of electrical and mechanical design are highly specific, if not unique, to the requirements and constraints of the industrial environment. To mount components so they can withstand vibration and shock for example, or to seal displays and keypads from liquids, dust and other environmental hazards is highly specialized knowledge that most engineering design teams struggle to master. Developing those skills from scratch is a costly and time-consuming effort.

Finally, do not discount the complexity of software development for even a simple human-machine interface. Today, most displays provide graphical feedback to the human operator and intuitive navigational elements with a three-dimentional »look and feel». The demands of programming in a graphical environment are many times more complex than programming for character-only displays.

Prototyping
It is important to prototype early and often in the design phase of a new product. Assess your company´s ability to develop mechanical prototypes quickly and cost effectively. Do your engineers have access to a 3D printer, for example, or will they have to send CAD files to an outside service?

Testing
How will your engineering team address the issues of testing both the hardware and software components? Does your team have the capability to design and build test fixtures and write the testing software? Also, fixtures and software must be created prior to the final assembly of a product. Does your company have the equipment to perform environmental tests?

Iteration
How many iterations of a design will your product development schedule allow? There are many potential failure points in the design and manufacture of a human-machine interface. Multiple re-designs and prototypes can use up critical weeks of development time. Yet most complex engineering projects require from three to six prototype stages to fully optimize the final product.

Final Testing and Certification
The final testing and certification could be a demanding discipline. Depending on the environment in which the machine will be used, HMIs may have to be tested for operation over for example extreme temperature ranges, as well as for thermal shock as devices are taken instantaneously from one temperature extreme to another. They may have to meet humidity requirements or be tested for sealing against immersion or high volume liquid spray. They may need to meet vibration and shock tests, and they must withstand electrostatic discharge and electromagnetic interference. …../Continued on the next page.