Page 41 - MetalForming Magazine March 2022

A proximity sensor (its yellow face can barely be seen) monitors spring stripper-plate travel. If the stripper fails to reach its full depth at the bottom of the stroke, due to a foreign object coming between the strip and the stripper, the control detects this and stops the press.
accelerated machine wear and even major mechanical damage to the press- es. Proper setups, along with ensuring that the presses are working within their capabilities, will help avoid unscheduled maintenance and unplanned downtime.
Also easing the drain on the main- tenance department are powerful diag- nostic functions inherent in modern press controls that can identify faults causing a press to shut off. Often, this type of fault identification allows the production team to clear issues without assistance from maintenance. For example, consider an air line or piece of scrap that shifts and blocks a light curtain. Such a fault can be identified clearly on the press control and allow operators to resolve it themselves.
In addition, even when a fault requires intervention from a skilled tradesperson or maintenance techni- cian, information provided by the press control allows them to quickly identify the problem, especially when faced with intermittent shutdowns. Once identified, repairs often are simple to execute. Some machine controls even maintain a running history of the faults, including details such as when they occurred. Such detail can prove invalu- able to technicians, preventing them from needing to spend hours at the press trying to capture the cause of an intermittent fault and instead allowing them to immediately begin making the necessary repairs.
Most recently, metal formers have begun to leverage artificial-intelligence (Al) capabilities of press controls, for machine-health monitoring. This tech- nology provides predictive and even prescriptive capability to multiply the impact of the service team. For example, we can use analog sensors to detect and measure temperature, pressure, vibra- tion, current draw and even sound, gathering and analyzing such data con-
tinuously. With AI
monitoring and diag-
nostics available in real
time, machine health
and the prediction of
future downtime
occurs before a break-
down. AI-equipped
controls aim to eliminate unplanned downtime altogether, allowing metal formers to task fewer technicians with equipment-maintenance functions while keeping machine availability at all-time highs.
Sensors to Monitor the Process
In addition to press monitoring, sensors also can monitor the tooling and even the auxiliary equipment around the press. Tooling sensors first and foremost provide protection to prevent die crashes. Sensors can detect critical events during press operation and if events in the tooling fail to occur as required, they signal the press con- trol to issue an emergency stop com- mand to halt the ram motion—quickly and before tooling damage occurs.
One disastrous, damaging press stroke leads to more than just the cost of the parts required to repair the dam- age. The metal former also must account for the labor costs associated with calling to the scene an experi- enced die maker, as well as additional costs for an expedited repair or over- time hours on weekdays or on week- ends. While all of that happens, the press sits idle while production scram- bles to identify the next job it can run and set up the tooling and coil.
Among the events monitored by sensors in progressive dies, feed pro- gression perhaps is the most critical. During material feed, several oppor- tunities for errors exist that can prevent accurate strip advancement. Among them: The feed can slip; the stock can buckle if it encounters resistance due
to camber or wear; punches can snap off and prevent the stop from advanc- ing; and scrap can fail to drop and block the advance of the strip. There is little room for error, as the tooling requires strip positioning with accuracy meas- ured in the thousandths of an inch.
As a relatively simple way to monitor strip progression in a progressive die, stampers can place grounding wires in the tooling that the strip contacts when in its final feed position. Other more precise options: Install proximity sensors to monitor the strip; use sen- sors to detect the position of a French notch-style lever-arm; or use a fiberop- tic or laser-type sensor.
Likewise, in transfer tooling, sensing proper part placement into each die station is the equivalent to sensing strip progression in a progressive die. The transfer tooling must properly place and seat each part in its die sta- tion before the ram closes. Typically, the transfer-tooling end effectors include sensors to ensure proper con- trol of the part during transport to suc- cessive die stations. The tools are designed with positive location features to ensure proper part positioning before the end effector releases the part into the die. This differs greatly from operations using hand transfer of parts; here we trust an operator to ensure proper part placement before initiating the next press stroke.
Part and Slug Ejection
...is another high-priority event that stampers typically monitor. Closing the tool on a formed part that failed
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