This is the final of a three-part series that spoke to the various feedback devices that are provided as options on Parker Servo Motors. Part 1 & Part 2 provided the basic theory of operation for the devices and provided some guidance on why you might choose one versus the other, along with some helpful formulas for calculating required resolution. The following is a quick summary and recommendations on selecting the best feedback device for your motion control application.
Incremental encoders (optical)
Good resolution - up to 20,000 ppr on standard Parker product
Good for applications where going back to home for out of application situation (power down) is not a concern
Provide absolute position upon powering up (no homing required)
Provide a very high resolution
16 bit = 65,536 ppr
20 bit = 1,048,576 ppr
Options for memory download to support “smart” encoder option
Option to allow for single cable from the motor for power and feedback
Good resolution (12 bit)
Very rugged – 40g vibration and 200g shock
High temp suitability – up to 200 deg. C
Provide absolute position within a single turn
Accuracy not as good as incremental or absolute encoders
Article contributed by Jeff Nazzaro, gearhead and motor product manager, Electromechanical & Drives Division, Parker Hannifin Corporation.
31 Jul 2019
In an industrial manufacturing environment, t-slot framing is often used for workstations, machine guarding, enclosures, tables, carts and more. When you have your initial idea for building with t-slot framing, how do you convey the concept? Do you use a piece of paper, CAD or even the famous napkin to sketch out your thoughts?
Traditionally, and still today, the “napkin sketch” method is how most t-slot aluminum framing companies encourage the user to send in information. It is very effective and allows the customer to quickly convey their ideas.
You might notice a trend that takes the customer from the “paper napkin sketch” to the “electronic or digital napkin sketch.” With the increasing use of 3D CAD systems, customers can use electronic tools to create their designs. The user libraries can be downloaded from the web and all the parts and components become available for use in your CAD system. Some companies offer a plug-in to a specific 3D CAD system. This means that their software works with that specific 3D CAD system, which may or may not be the system that you’re using. Other companies offer a standalone tool that can export files into various 3D CAD formats.
Here are a few ways to access these tools
With so many projects and the time constraints that go along with them, it is important for users to work efficiently. Using an electronic tool to “sketch” your design will allow you to import that assembly into your current project. This is very valuable if it is part of a larger machine design. Also, being able to interact with a trusted partner to quickly receive a quote helps with the process of understanding project costs along the way.
Are you ready to take your concept to completion? Start with the Parker T-Slot Aluminum Design Architect (TADA). This is a free tool that you can use to design your tables, carts, workstations, enclosures and more. We also have a network of Design Centers located throughout North America that are ready to help you with your design needs using T-slot aluminum framing.
Parker is making t-slot aluminum framing design easier than ever. For mechanical design engineers, lean manufacturing leaders and do-it-yourselfers, the Parker T-Slot Aluminum Design Architect (TADA) software allows you to take more creative control over your assembly designs. Download your free, fully functional copy today.
Article contributed by Mario Mitchell, product manager for T-slot Aluminum Framing, Electromechanical & Drives Division North America, Parker Hannifin Corporation.
11 Apr 2019
Stretch films are essential in the packaging industry as they provide a versatile and high-quality solution for packing products in a safe and economical way. Film is produced by a flat die extrusion process where AC motors and AC variable speed drives play a significant role in ensuring a high-quality output.
The process starts with the extruder that is essentially a pump that melts and transports fluids of high viscosity. The polymer enters into the extruder via a gravimetric feed, and through the combined actions of heat and mechanical stress, the material is melted, mixed and pushed through an extrusion head to give the desired shape. After exiting the extrusion head, the material enters a cooling unit, here water cooled ‘chill rolls’ reduce the temperature of the film before it is finally wound onto rolls.Extruder
The extruder consists of a hollow cylinder in which rotates a single or double screw driven by an electric motor; this is usually coupled to the plasticising screw by a gearbox. The motor provides the torque required and rotates at a speed necessary to obtain the expected melt flow rate. Any failure in the precise control of the screw speed can cause changes in film thickness in the machine direction.
For the past 20 years, AC motors have typically taken over from DC motors in the control of the extruder screw in cast film line applications. They have been able to deliver many advantages in terms of convenience, reliability, low maintenance and a reduction in the overall dimensions of the system solution. AC motors are controlled by AC variable speed drives that guarantee stable rotation - even at very low speeds (via a closed loop circuit through incremental encoders), provide short circuit protection (low or high voltage), and incorporate EMC filters to eliminate electrical noise and interference.
In recent years, along with AC motors and drives, torque motors have also been utilised in screw extrusion control. These offer a complete direct drive solution that does not require the assembly of different elements such as a gearbox, belts and pulleys. Torque motors guarantee uniformity in the motion, linearity and constancy in the extrusion of the plastic material.Cooling section
As previously mentioned, when the material leaves the extrusion head, it is melted on chilling rolls that form the cooling section of the cast film production line. The cooling unit is comprised of a primary quenching roll, that cools the film on one side, and a secondary roll, that cools the film on the opposite side. It also includes a motorised roll positioning system for correct vertical and cross machine direction alignment of the rolls, and in many cases a vacuum box and/or air knife.
The rolls must be perfectly aligned with the web to guarantee uniform tension and to minimise thickness variations across the width of the film. In addition, the angular velocity of the rolls must be well controlled to prevent film thickness fluctuations in the machine direction.Accumulator and winder section
Within the cooling and winding sections we find the accumulator, this is used to allow splicing of the web being fed from an empty winder to a full winder at zero speed without stopping the line.
At the end of the process, a further winder brings the extruder material onto rolls. The winding process has to preserve the film’s properties and dimensions when the rolls are unwound in other downstream processes.
There are several different types of winders, although the typical one used one in cast film applications is a ‘turret’ or ‘centre’ winder where the web tension decreases as the roll diameter increases.
All the movements performed in the cooling, accumulator and winder sections are driven by AC motors and drives that govern the web speed and the correct web tensioning.
AC Drives and Motors
AC Drives with high-end control are very important for guaranteeing high-quality film throughout the process. Easy-to-configure software for the closed loop control and optimum efficiency for many different types of material is a vital element of a cast film line system and process.
Parker's AC30 series with power ratings ranging from 0.75 to 450 kW coupled with the company’s Quicktool software with full IEC61131PLC functionality or Parker DSE Lite software, provides all the features needed to achieve optimum synchronisation between all line sections. It allows customers to create, parameterise and configure user-defined applications using dedicated function blocks such as the winder, PID and diameter calculator. The AC30 series also provides access to a large library of application macros and worked examples.
Connectivity via EtherCAT, Profinet, Ethernet IP and Modbus TCP IP through a dual Ethernet port enables communication between individual drives in a simple and flexible way and supports intelligent data analytics and connection to external servers. The line setpoint can be sent through a very fast channel supported by 1588 time synchronised peer-to-peer communication, and each part of the machine has its own regulation, either within the drives, or through communication protocol by the PLC.
An animation shows how high a performance drive solution supports the optimal control of a cast film line.
Article contributed by Jean-Philippe Olry, application engineer industrial market, Electromechanical & Drives Division Europe of Parker Hannifin Corporation.
4 Apr 2019
Using a variable frequency drive (VFD) can be beneficial in many constant speed applications driven by electric motors, such as those that require controlled starting and have been historically served by a reduced voltage soft-starter (RVSS). While an RVSS and a VFD can both provide a controlled start, let’s examine the benefits of each technology and when it makes sense to use one over the other.
The differences between RVSS and VFDs and when to select one or the other for an application is determined by the following factors (when using a NEMA design B three phase induction motor):
An RVSS can be used to limit inrush current and reduce mechanical stresses on the motor and device it is powering during the starting cycle. The RVSS ramps the starting voltage from 40% (typical) to 100% over a set time (2 - 15 seconds typical). Starting torque is significantly reduced, rising to full torque at rated voltage.
By using an RVSS, locked rotor torque will be approximately:
Rated Torque x 2 x (% applied voltage)2
At a 40% start voltage, locked rotor torque will be:
Locked Rotor Torque = Rated Torque x 2 x (0.40)2 = 0.32 (32% of rated torque)
Because both the voltage and frequency are varied with a VFD, the motor will be at 100% flux at any speed resulting in the ability to produce 100% torque at 100% current at any speed below base speed. Therefore, a VFD can be used as a full torque soft starter in place of an RVSS. When used in this capacity, a VFD is capable of starting loads that require up to 200% torque such as mixers and production machinery with no inrush current.
Parker has recently introduced the AC10 series of general purpose VFDs, available at 230V to 20HP and 460V to 250HP and offer:
Article contributed by Bill Riley, business development manager for the Drives Business Unit, Electromechanical & Drives Division North America, Parker Hannifin Corporation.
6 Mar 2019
For a long time, the use of hydraulic power in industrial processes has been associated with its traditional benefits: high power density, precise control, and long-term performance. Yet these advantages typically come hand-in-hand with equal numbers of potential drawbacks: excess noise, heat generation, and inefficient energy allocation. As we move forward, technologically advanced industrial equipment now requires hydraulic systems that can provide quieter, more economical and more efficient solutions.
Where wasted energy and resulting carbon emissions might have previously been seen as inconsequential, a switch to a tightly-modulated hydraulic system fitted for specific tasks is essential in today’s globally competitive and eco-conscious economy. With various industrial machinery (including die casting machines, presses and plastic injection moulding machinery) placing different demands on hydraulic control, you may wonder: how can highly complex hydraulics systems be adapted for individual requirements?
Matching optimum performance to size requirements
Taking one application example into consideration – injection moulding machinery (used in rubber, thermoplastic and other polymer industries); Parker has developed an immersed servo motor pump system with the aim of enhancing hydraulic reliability and reducing energy consumption. Hydraulics have long been utilised in this industrial process; with a hydraulic power unit (HPU) as the source and with very large capacity pumps and motors to ensure steady performance. However, Parker’s solution brings in three separate elements (a pump, a servo motor and a drive for control) to match flow rate to the particular requirement, primarily through the rotational speed of the motor.
From opening and closing moulds to plasticising and injecting, there are many auxiliary movements – often occurring in parallel – that take place within plastics machinery. They must be supplied centrally with the required flow and pressure over the briefest of cycle times. Controlled by the speed and torque of servo motor as part of Parker’s solution, careful flow and pressure regulation allows for greater energy efficiency. With the high maximum speed of the small vane pump, a very high volume flow can be achieved with the smallest size. Therefore, component size can be optimised to suit their need and investment costs reduced.Selecting a complete solution
Alongside hydraulic systems available for injection moulding machinery, Parker offers a full-system solution, the Drive Controlled Pump (DCP), which combines a versatile range of AC drive controllers, motors and pumps into tailored packages for the most diverse applications. With the incorporation of an alternating current drive controller, the speed range can be set in advance to a predefined cycle. Whether for a long or short duty cycle, the precise amount of hydraulic power required can be calculated for any particular point in time. When selecting between vane pumps or axial piston pumps, factors of output, required minimum and maximum speeds can be assessed and taken into consideration.
Parker’s DriveCreator dimensioning software tool enables the creation of an energy-efficient, speed-controlled, electrohydraulic DCP solution, while its start-up tool simplifies the task of putting the DCP into operation once selected. To discover more about recommended combinations of individual components, please click here.
This article was contributed by Vincent Sinot, key account manager, Parker Sales Company France.
12 Feb 2019
Although the basic recipe for the solid soap bar has not varied much for decades, the process of making this basic commodity has changed significantly since the advent of industrialisation. Modern factories now produce thousands of pieces of soap per day.
Hirtler Seifen GmbH, from Heitersheim, Germany, is one such soap manufacturer, but unlike many of its peers, it has a history spanning over 125 years. From its traditional origins, the company has grown to become one of the largest manufacturers of soaps and cleansing products in Europe, delivering its products to customers all over the world.
However, the company’s plant was in need of an upgrade to optimise its production line for efficiency, production output and recipe-change flexibility. Hirtler Seifen’s 20-year-old digital servo controllers had reached the end of their useful life, and the rest of the system’s associated components could not be upgraded without undertaking a complete system overhaul.The need to increase speed
Automation solution providers Mattke AG from nearby Freiburg were tasked with bringing Hirtler Seifen’s production line completely up to date with the newest precision movement technology. They realised that this was more than just a simple controller exchange task, because Hirtler Seifen’s primary goal was to increase its production rates from 5,000-6,000 bars of soap per day up to 15,000. They also required greater flexibility to accommodate production line changes.
As the plant was already running 24 hours a day, seven days a week, reducing maintenance-related downtime through better equipment reliability and positioning accuracy was identified as one of the ways in which production could be stepped up.
The decision was made to completely replace the linear axles, motors and servo controllers, from the pre- and post-production handling portals to the cooling system for the soap-free cleansing bars. Mattke selected Parker's LBB080 toothed belt linear actuators, SMH-Series low-inertia brushless servo motors and COMPAX3S single-axis servo drives for the job.A four-week deadline
Hirtler Seifen set Mattke a challenging delivery date: the factory was to be closed for just four weeks, during which time the entire refit had to be completed. Throughout this very tight overhaul period, Parker provided essential custom manufacturing support to Mattke.
After the CAD drawings were completed and system requirements were finalised, Parker worked quickly to complete the mechanical axles for the handling portals, complete with electric thrust cylinder, linear actuators, servo motors and drives, in just three weeks – half the time usually required for such a task. During this time, Mattke’s engineers were hard at work setting up the system software. When the mechanical equipment arrived on-site, the team had just one week to install and set up in time for production to begin.Increased production and flexibility
The project was delivered on time thanks to the close collaboration between Mattke and Parker.
“Our partner, Parker, who manufactured the mechanical axles, put in a great deal of effort and provided a high degree of technical expertise.”
Simon Hübner, technical director, Mattke AG
In addition to the significant increase in volume provided by the overhaul, the new system now offers Hirtler Seifen increased flexibility.
Each of the five products that are currently manufactured by Hirtler Seifen can be manufactured at the same time, but still managed separately. And if the soap manufacturer wishes to add more products to the production run, this will be an easy task.
This article was contributed to by Michael Boerner, key account manager, Automation, Parker Hannifin Germany
1 Feb 2019