* novel task-oriented HMI simplifies control of plunge grinding operations
Naperville, IL, August 11, 2015 - A comprehensive upgrade of classic high
manufacturer to greatly simplify precision grinding operations on axle
forgings. A key element of the project - which has been managed by APeC
Integration Services, Inc - is the retrofit of customized CNC control based
on NUM's powerful Flexium platform.
Based in Wattsburg PA, APeC is an electrical systems integrator specializing
in upgrading machine tools with modern PLC and CNC control systems.
Established in 1989, the company has built a reputation for enabling clients
to maximize the longevity and performance of their machine investments. Key
retrofit services include upgrading servo and spindle motors and drives, PLC
integration and custom machine controls, and complete CNC replacement.
The machine tools in this particular project are high capacity Landis
centerless grinders, which utilize a dressable grinding wheel and a plunge
grinding cycle to create precision profiles on railcar axle journals. During
grinding, both the axle workpiece and the grinding wheel rotate in the same
direction, which means that the two surfaces are moving in opposite
directions at the point of contact, resulting in smoother operation. Once
the machine is up to speed, the grinding wheel is fed - or 'plunged' - into
the workpiece and makes continuous contact with a single point along its
length. The plunge action is controlled by a servo-driven axis grinding at
several feed rates, with transition points monitored by in-process gauging.
A built-in automated two-axis dresser system with a diamond tipped tool is
used to dress the grinding wheel whenever necessary.
This is the second time that APeC has improved the performance of these
grinders with control systems based on NUM CNC kernels. The original
machines were hydraulically actuated and equipped with tracer type wheel
dressing systems. In the mid 1990's, APeC performed a full mechanical and
electrical upgrade on each machine that included retrofitting a modern CNC
system and in-process gauging instruments. On that occasion, the company
based the upgrades on NUM's Power 1060, which at the time was regarded as
one of most flexible and user-friendly CNC systems on the market.
After a further 20 years' full-time service in a busy production
environment, the machines became due for another mechanical and electrical
upgrade. APeC had supported the machines and worked closely with their
operators throughout this period, during which time it had also developed a
number of ideas for making the machines even easier to operate and more
productive. The upgrade program offered the ideal opportunity to put many of
these ideas into practice.
To expedite machine upgrade and minimize the impact on its customer's
production schedules, APeC managed a three-way development partnership. All
major mechanical re-design, hydraulic, lubrication, and geometrical
rebuilding aspects of the project were handled by EURO Machinery
Specialists, Inc., a company with some 45 years' experience of refurbishing
and modernizing high value metal cutting machine tools. On the control side,
APeC collaborated with NUM USA to develop a unique and intuitive human
machine interface (HMI). This enables operators to learn how to use the
machines very easily and quickly - even if they are unfamiliar with these
types of grinders. Customer benefits include improved worker satisfaction,
less need for training and increased machine productivity.
According to Dave DeCoursey of APeC, "A key project goal was simplifying
machine operation as much as possible. NUM's open Flexium CNC platform
provides the control flexibility and HMI customization facilities that we
needed to develop individual, task-oriented screens. The user interface is
consequently now much more ergonomic. Most operations, such as offset
calculations, calibration, dressing and automatic grinding cycle initiation,
are now performed using single, virtual pushbuttons that are only displayed
Each machine upgrade uses several NUM products, including the CNC kernel,
touch-sensitive operator panel, servo drives and motors. The Flexium CNC
system uses EtherCat I/O communications, making it simple for APeC to
implement an advanced plunge depth control architecture. The in-process
gauging instrumentation previously used for this aspect of machine operation
has been replaced by a linear encoder, which facilitates fast and accurate
depth control, as well as providing real-time feedback to the operator
throughout the grinding cycle. The main control screen features two large
analog-style dials, supported by digital displays, which derive their input
data from separate measurement probes located along the length of the axle
journal, allowing the operator to monitor taper tolerance very easily.
The client- and application-specific HMI software that APeC has developed
for the grinding machine upgrade is task oriented. It uses individual
screens that are tailored to the application, with clear context-sensitive
functions that help to prevent human error. By using the Extended NCK Access
(ENA) facilities of the Flexium CNC controller, each custom PLC-driven
visualization can control and monitor the CNC functions directly. This form
of control approach is specially useful for automated teach type
functionality, such as guiding an operator through machine start-up and
preparing for automatic cycles.
For example, the start-up screen initially displays only the status of the
CNC system and a single 'Shutdown' button. As soon as the CNC system
indicates that it is ready, the start-up screen displays two additional
buttons: Home Screen and Manual Operation. When the operator touches a
displayed button and causes a change of screen, the software automatically
alters the CNC mode accordingly and selects the corresponding part program
if applicable. By confining the operator's available options to just those
that are appropriate at the time, the software helps to ensure consistent
and efficient machine use.
Another major advantage of this type of control approach, with extended
access to the NCK, is that it can be used to help the operator with tool
offsets and adjustments to part program dimensions. When the grinding wheel
or dressing tool is replaced, the operator can manually position the tool on
the desired surface of the wheel, access a password-protected screen and
then simply press a button. The offsets are calculated and pushed into the
dressing program automatically, using the ENA facility. This same facility
allows the operator to alter dressing dimensions and sparkout setpoints
simply by adjusting a value up or down - these are then pushed into the
corresponding part program.
Steven Schilling, General Manager of NUM Corporation in Naperville,
Illinois, says, "The open architecture and advanced functionality of Flexium
CNC systems enable engineering companies to implement innovative machine
control solutions for retrofit or new machine tool projects. In this
instance, APeC and Euro Machinery Specialists, with NUM's support, have
created a CNC retrofit that adds significant value to the customer's
existing manufacturing facilities."