Mitsubishi Electric is launching the MELSERVO MR-J4 series of servo amplifiers and motors, together with associated motion control modules to suit the full range of Mitsubishi PLCs and PACs. The company says this next-generation servo systems offer safe, user-friendly and energy-efficient motion control for machine builders, systems integrators and machine users seeking to improve the performance of existing equipment. Moreover, the MR-J4 series is claimed to represent a significant advance in servo system technology to the benefit of machine builders and end users alike. For example, in the food industry it could be possible to upgrade equipment by installing MR-J4 servo technology to reduce give away such that the retrofit paid for itself in only a short period.
According to Mitsubishi, the MELSERVO MR-J4 family enables machine builders and end users to improve productivity and reduce energy costs. Numerous innovative and user-friendly functions have been incorporated to boost performance while minimising the effort required for engineering and setting-up servo systems.
The series features single-, dual- and three-axis amplifiers for improved economy, greater energy efficiency and reduced panel space requirements. All of the servo amplifiers can operate with rotary, linear and direct-drive motors from other manufacturers, in addition to the new Mitsubishi J4 servo motors. Amplifiers are available from stock for use with 200V and 400V motors.
By using regenerative braking, significant savings in energy consumption can be achieved, depending on the application; in some cases savings of 30 per cent are possible. Multi-axis amplifiers are the most effective way to achieving these energy savings, but regenerative braking and the resultant energy savings can also be implemented across multiple single- or multi-axis amplifiers. Mitsubishi believes the MR-J4 series is the first family of servos to have been designed specifically with energy savings in mind.
In addition to saving space in the panel, there is a major saving in engineering and commissioning time thanks to the one-touch auto-tune function that matches the machine mechanics to the servo system - and does not require an engineer with servo tuning skills. This 'Advanced Vibration Suppression Control II' function operates in real time and is dynamic so that the MR-J4 system tuning is adjusted automatically should the machine operating conditions change over time due to wear, a product change or other external factors. This new version of the auto-tuning function is a development of that provided with the MR-J3 series servos. Further potential benefits of the sophisticated auto-tuning include improved product quality and faster machine cycle times.
Mitsubishi is offering MR-J4 servo amplifiers rated from 0.1kW to 55kW in two versions: the MR-J4A servo amplifier provides analogue and pulse train connections and is designed for conventional control systems and for speed, torque and closed-loop position control; the MR-J4B servo amplifier comes with connectivity to Mitsubishi Electric’s SSCNETIII/H high-performance servo network to meet the needs of integrated automation systems where complex multi-axis motion control is required. SSCNETIII/H control information is delivered over a full duplex 150Mbps fibre-optic bus, which simplifies connection and commissioning, and permits synchronous co-ordination of up to 96 axes. Both versions of the amplifier come with built-in local I/O for interfacing with signals such as overtravel limits and print mark registration.
Built-in machine condition monitoring
MR-J4 amplifiers also include a life diagnosis function that monitors the condition of the amplifier at a component level and notifies the user of any degradation in its operation. This innovative feature can also monitor motor current and recognise changes in machine dynamics - such as increased vibration and increased motor torque - which aids preventative maintenance, minimises machine downtime and extends machine lifetime.
The carefully matched servo motors are fitted with 22-bit absolute encoders as standard, corresponding to more than four million pulses per revolution, which is claimed to out-perform the accuracy of other servo motors on the market by a factor of four. This results in excellent true-running characteristics and maximum positioning accuracy. Combined with the processing speed of the MR-J4 servo amplifiers and their 2.5kHz frequency response plus inbuilt vibration suppression filter, machine performance can be improved dramatically, with minimised positioning times, reduced cycle times, greater throughput, faster product changeovers, and reduced 'give away' in packaging and bottling applications. Other advantages include, for example, the ability to dispense liquids without stray drips that are wasteful and require time-consuming cleaning, and better control of filling with less aeration.
Built-in safety functions
Features such as STO (Safe Torque Off) and SS1 (Safe Stop 1) are built in as standard, ensuring servo system safety meets EN 61800-5-2. In addition, SS2 (Safe Stop 2 - with torque controlled to maintain a set position), SOS (Safe Operating Stop - with standstill monitoring), SLS (Safe Limited Speed), SBC (Safe Brake Control) and SSM (Safe Speed Monitoring) options are available.
Set-up and diagnostics
MR-J4 servo amplifiers are programmed using the MR Configurator2 software tool, which is part of the integrated iQWorks suite. Functions include calibration, monitoring, extensive diagnostics, read/write of parameters and test operation. The MR Configurator2 ensures stable machine system design, with optimum control and shorter set-up times.
In line with Mitsubishi's longstanding commitment to customer service, the MR-J4 servo amplifiers and motors are backwards-compatible so can be fitted in place of previous-generation MR-J3 products. For example, a J4 amplifier can be installed in place of a J3 amplifier and configured to function exactly as a J3. Similarly, a J4 motor can replace a J3, as it can perform the same way and the mounting dimensions are identical (J4 motors are approximately 10 per cent shorter). Not only does this policy make it easier to replace components but it also enables end users to upgrade machines in a way that is easy to manage.
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