Automotive technicians assembling prototype vehicle bodies during pre-production use manual punch-riveting tools to join individual sheet-metal parts. Several thousand joints are required per vehicle, and tools must be compact since space is often limited.
Bad joints, which are very costly to repair, can occur if the technician does not set the tool correctly before triggering it. During use, the tool-head is often partly hidden from view, so a sensing system must confirm that the operating ram is fully retracted and prevent the tool from operating if the ram is not in the correct position.
A pneumo-hydraulic cylinder drives the ram, and the compact nature of the tool limits the allowable sensor size. The sensing face is exposed to the high-pressure side of the hydraulic circuit, so the sensor must withstand continuous pressures up to 500 bar (7255 psi) and pressure spikes of 1000 bar (14,510 psi).
Robust inductive sensors from the Contrinex Extra Distance family, High-Pressure range, withstand the high operating pressure of this application. The extended operating distance of patented Condist technology allows the use of thick, hermetically sealed ceramic discs on the sensing faces without compromising the sensors’ performance.
These lightweight M5- and M8-diameter embeddable sensors are 27 mm and 30 mm in length, respectively. The sensors are mounted directly into the wall of the cylinder and do not interfere with the normal operation of the tool. Sensing distances of 1mm (M5 sensor) and 1.5 mm (M8 sensor) eliminate any risk of internal mechanical damage through contact with the ram.
The sensors have an industry-standard PNP normally-open configuration and connect with the customer’s control system via a flexible PUR-sheathed cable. Vacuum-encapsulated electronics ensure excellent resistance to shock and vibration, and no additional electrical or mechanical protection is required.
Previously, users of the punch-riveting tools were unable to check the position of the operating ram with the tool in situ and either incurred downtime or risked costly bad joints. Contrinex high-pressure inductive sensors satisfy the manufacturer’s requirement for small, lightweight, ultra-reliable sensors with an attractive total cost of ownership. The no-cost option of the industry-standard IO-Link protocol ensures that best-in-class performance is coupled with ultimate ease of use in even the most demanding circumstances.
Contrinex sensors and more information are available from PLUS Automation.