Technology You Can Use 2442

Wireless Sensing Bridges the Gap

Noncontact transmission of power and data provides automatic safety switch

Sensing the positioning of a large progressive stamping die to avoid damage is normally a routine task for inductive and photoelectric proximity sensors. When the die is in two pieces that are separated by 0.125-inch air gap, the design requires a more innovative solution. Wired connections between the sensors and the power would inevitably result in damaged connectors or wiring. To solve this problem, engineers from Balluff and Ultra Tool & Manufacturing made a wireless connection.

Locating a power remote system, with noncontacting transmission capability on one side of the air gap and sending the power to a receiver and sensors on the other side is the first step. Inductive coupling links the remote to the receiver that is approximately 0.25-inch (from 4 to 12 mm) away and the sensors are hard-wired to the receiver unit. The same inductive coupling technique transmits the sensor measurements from the receiver unit to the main control system. The technology is based on straightforward inductive principles. For a primer, go to http://rbi.ims.ca/4390-508 .

Using the wireless remote, heavy dies are positioned without wires crossing over the die. This eliminates concern for wires and connectors initially and during servicing. Ultra Tool & Manufacturing designed steel mounting blocks to protect the transmitter, sensors, and receiver, and incorporated the air gap for the power remote in their tooling.

The position sensors' role is for error proofing-to prevent costly damage to the large die. Four position sensors mounted in the die ensure that the various steps in the progressive die happen in the proper sequence. The sensors detect slugs from the stamping fallout, avoid dual hits, ensure that the metal being stamped is in the right position in the die as it moves forward, and that material is ejected correctly. The sensors send back the position information from the stamped material to the central controller. When a problem is detected, the sensors trigger the press's emergency stop system. The combination of power remote and position sensors ensures that the part is being made correctly and in proper position for the next step.

CONTACT:Tom Draper, Balluff Inc. Tel: 800-543-8390; e-mail: [email protected]http://rbi.ims.ca/4390-505
Ultra Tool Manufacturing Inc.http://rbi.ims.ca/4390-506

Rotary Tool Integrates Wet Cutting Capability

Direct drive brushless motor provides high-positioning accuracy

Wet cutting with rotary tools has typically meant adding external components that also add friction and inertia to the process. The external approach uses a clear aperture rotary union with a correspondingly large seal diameter to provide clearance for the tube material and transfer of the pneumatic control through the rotating shaft. A separate pneumatic gripper or collet assembly is then added to provide the automated material handling. Using a "designed for" instead of "adapted to" approach, Aerotech engineers designed functions into a direct-drive brushless motor to produce a system that simplifies wet cutting and improves performance.

Aerotech's ASR1200 integrates both a pneumatically operated collet chuck for automated material handling and a sealed water jacket for wet cutting processes. A threaded retaining cap for the collet enables a simple changeover with full clamping force applied when no air pressure is present. A custom-designed frictionless, seal-less rotary union delivers air to the rotating collet assembly. The combination collet chuck and rotary union reduces friction by as much as 50 percent.

The fluid delivery system uses an O-ring assembly inside the unit to seal the tubing against the inner diameter (I.D.) of the shaft. The seal between the outer diameter of the tubing material and the I.D. of the rotating shaft of the stage allows the delivery of fluid through the center of the tubing material being laser processed providing the wet cutting capability. Since the shaft of the stage becomes a sealed pressure vessel rotating with the tubing, there is no friction-related wear between the seal and the tubing.

The direct drive brushless motor technology with the integrated functions provides positioning accuracy of plus or minus 72.8 murad ( plus or minus 15 arc sec) and repeatability of plus or minus 14.6 murad ( plus or minus 3 arc sec), peak acceleration of 35,000 rad/s2, (continuous 13,600 rad/s2), and higher top speeds (2,000 rpm) than gear- or belt-driven mechanisms that are typically limited to 100 to 500 rpm. The unit's resolution is 2,048 cycles/rev with an analog (sin/cos) output. The maximum axial load is 3.0 kg (6.6 lbs) and the maximum radial load is 2.0 kg (4.4 lbs) with maximum inertial loading of 5 x 10-4 kg-m2 (0.07083 oz-inch2).

CONTACT:Steve McLane, Aerotech Inc. Tel: 412-967-6854;
e-mail: [email protected]http://rbi.ims.ca/4390-507