Faced with competition from low-cost economies, European machine builders need to find ways to maintain their market share. One strategy is to use automation products that require less engineering time and reduce the component count, thereby saving valuable resources. Examples of this include motors with integral drive electronics, and linear actuators that combine the structural elements, bearings and power transmission components (typically a ball screw or belt drive) within a single unit. Similarly, design engineers can today specify inverter drives that deliver performance that competes with more costly and complex servo drives, stepper motors that offer near-servo performance (see panel page 58), and drives and motion controllers that can undertake tasks that would normally require a separate programmable logic controller (PLC).
One European company that is actively developing automation products with greater functionality is Lenze. For example, at the end of 2010 the company extended its L-force 8400 range of frequency inverters with the addition of a Topline version for servo applications. The 8400 range is already proven to give performance up to low-end servo levels - for example, up to 180 cycles per minute with a standard asynchronous motor - but now the Topline versions operate with synchronous motors to deliver performance advantages thanks to the lower inertia of these motors. Being based on high-volume inverters, Topline units are said to be less expensive than even low-specification servo drives (Fig.1).
Lenze's 8400 Topline units were unveiled at the SPS/IPC/Drives exhibition in November 2010, designed for repetitive positioning tasks such as pick-and-place, and storage and retrieval units; 200 per cent overload is available for three seconds and, depending on the application, up to 300 cycles per minute can be achieved with 0.01mm accuracy. In line with the lower-specification Stateline and Highline versions on which it is closely based, the Topline series is available from 0.25kW up to a newly extended maximum of 45kW.
In complex and multi-axis machinery, Topline is said to be easy to integrate. One software application, Lenze L-force Engineer (which is free of charge for the basic version), can be used to set the operating parameters for all 8400 inverters, Lenze controllers, I/O (input/output) modules and HMI (human-machine interface) devices.
Another new product Lenze introduced at SPS/IPC/Drives is the 3200C controller that combines PLC logic, motion control and visualisation in a single unit (Fig.2). By bringing together the latest fast microprocessors with updated operating software, the 3200C delivers a tailored combination of hardware and software that can implement automation systems in a cost-effective way. Designed for centralised control systems, this new offering suits machines with single- and multi-axis drives, giving powerful control over a matching range of external drives and actuators.
Lenze says the 3200C controller is designed to integrate with the Lenze L-force I/O system 1000 to create a single control station with a fast 48MHz backplane bus and a 1 µs time stamp. Up to 64 I/O modules can be combined with digital and analogue I/O, temperature measurement, counters and encoder evaluation.
To ensure that the hardware remains reliable in industrial environments the 3200C uses flash memory for storage instead of hard discs, and the Intel Atom processors operate without requiring a fan - hence there are no moving parts. In the event of a power supply failure, an integrated UPS (uninterruptible power supply) ensures that the retained variables of the controller are saved.
A company well known for its 'smart' drives is Baldor Electric. And its Microflex e100 and Motiflex e100 single- and three-phase smart drives now benefit from new Mint Lite programming capability as well as being compatible with Ethernet Powerlink. These drives are available in a broad choice of power ratings up to 33.5A, with higher ratings coming soon. The versatile drives may be used to control rotary and linear servo motors, linear motors and closed-loop vector motors.
The embedded Mint Lite capability supports basic motion programming requirements, including performing relative and absolute moves, S-ramp profiles, jog and homing movements, changing target positions on the fly, registration moves and reacting to real-time trigger events. The programming facility enables standalone drives to act as controllers in automation and machinery tasks such as cutting or feeding to length, indexing axes, simple pick-and-place tasks, and making machine adjustments such as changing guides or backstops.
More flexible PLC interfacing is another notable feature. Drive manufacturers offer a defined process data exchange interface with PLCs (the drive profile), and the ability to program Baldor's drives means that the standard drive profile may be adapted, typically to simplify the communications process or to optimise the drive's performance characteristics for a specific application.
All of Baldor's Microflex e100 and Motiflex e100 drives come with built-in I/O as standard, plus Canopen manager capability to support distributed I/O expansion and HMI interfacing. Motiflex e100 drives offer card slots for further local I/O expansion and fieldbus connectivity. This versatility enables drives to be configured very cost-effectively to provide single-box controls for automation applications.
If used in a Powerlink system, the local intelligence adds versatile new system building capabilities. Critical events can be acted on, eliminating the impact of network and controller scan time latencies; the faster response of critical axes can therefore be translated directly into higher throughput.
Motion and machine control
Aerotech already has an extensive range of drives and motion controllers, but at the 2010 SPS/IPC/Drives Exhibition the company unveiled its new Motionpac integrated motion and machine controller system. This is described as a PC-based single development environment and machine controller that combines an industry-standard PLC engine with Aerotech's sophisticated multi-axis motion engine. The system is versatile and customisable, and includes programming options such as adding custom function blocks using Microsoft's.NET Framework or running Aerobasic programs directly on the controller and interfacing with other software such as Labview.
Aerotech explains that Motionpac enables users to control multi-axis motion trajectories to within microns using the company's direct-drive positioning mechanics, and with real-time and real-position data acquisition from its nanometre-level encoder technologies; at the same time the system can output position-synchronised pulses to control external events such as the firing pattern of a laser or precisely timed 'electronic gearbox' functions.
In addition, the single development environment is said to enable machine builders and OEMs to benefit from considerably reduced machine integration and build timescales, with the machine tags defined only once and accessible across all applications, regardless of the programming language selected.
For machine builders looking for something beyond a conventional PLC, Bosch Rexroth introduced the Indralogic XLC (extended logic control) towards the end of 2010. According to Rexroth, users can leverage a wide range of new functions to realise modular software projects quicker than before (Fig. 3). All planning, configuration, programming and diagnostic functions are standardised in a single engineering environment; motion control functions are also integrated. Indralogic XLC can be connected to various communication networks thanks to real-time communication via Sercos III and other common communication protocols such as Profinet RT, Profibus and Ethernet/IP.
Stepper motors replace servos
Nanotec Electronic's new SMCI36 motor controller is aimed at engineers who require quick, small and energy-efficient motor controllers for distributed applications (Fig.4). The company says that its Closedloop technology provides energy-efficient motor control and, with the field-oriented control, expensive geared servomotor systems can be replaced with more economical stepper motors. This is particularly true for rotational speeds of up to 1500rpm or torques of up to 10Nm.
Not only is the SMCI36 controller compact, but its Closedloop-capable encoder input means that the motor stator magnetic field is controlled via the rotary encoder, as with a servomotor. The stepper motor therefore cannot lose steps, even at maximum torque. In addition, the current is continually adjusted to suit the required torque, which substantially decreases current consumption and heat generation in comparison with conventional stepper motor controllers, resulting in a reduced electrical power requirement and a longer service life for components.
The combination of dspDrive technology and the SMCI 36 model is said to achieve a low-vibration stepper motor, as is typically required for medical technology, laboratory automation, optical devices and sensitive applications. Thanks to the software-based control circuit, both stepper and brushless DC motors can be controlled with the same hardware.