The DTS uses a 10-mm-pitch, toothed timing belt. Lugs affixed to the belt at equal intervals transmit timing belt motion to the carriages. The carriages, set flush with timing belt and sheaves, leave the entire plane above the DTS open for tool motion.

During dwell, a rotary bar along the front of the carousel locks carriages into position for repeatable precision at the workstations.

The printer maker found the DTS carriage lock system useful for holding carriage tolerance in the workstations at ±0.025 mm. The lock, which uses a pneumatically actuated bar to rotate tabs into corresponding slots on the carriages, eliminates the need for costly positional sensing and feedback beyond the simple limit switch. The locking system also clips expensive electronic drives out of the picture. Instead, an ac motor and low-backlash worm reducer are all that are needed to drive the belt.

Hepco's vee guides further enhance positional accuracy. The rigid way locates the carriages along the other two axes, which go unaddressed by the locking bar.

The carriages use threaded holes accessible from above, making removal and replacement of the various carriage plates an express operation.

Another feature useful to the printer maker was overload protection of the carriages. If a carriage jams in one of the workstations, the lugs employ spring-release tabs that trip out whenever belt resistance exceeds 60 N.

Engineers at Nagle Industries considered several options for the actuator assembly. Die casting or cold forming of components would be expensive, Nagle said. So would making them on a screw machine.

The material choice made it a snap to assemble this actuator for tilt steering wheels.

Plastic parts in place of, or in combination with, metal could bring down assembly costs by acting as their own snap-on fasteners, he explained. But short glass nylon lacked strength.

LNP Engineering Plastics of Exton, Pa., provided Nagle Industries with a long glass fiber-reinforced nylon 6/6, which joined plastic's forming ease with metal's strength. "The composite allows us to mount the cable actuator on the metal bracket without using any fasteners," Nagle said. The material strength is not compromised by its ability to flex without fracturing.

"The actuator arm is like a shaft on a golf club," Nagle said. "It receives a lot of torsional loading." The LNP composite resists twisting and deflection under load. With little shrink-age coming out of the molds, the material holds its original design well, an important consideration for snap-together assembly.

Modular design and control flexibility are key attributes of the motor controllers from Anacon Systems of Mountain View, Calif. Zahid Ansari, vice president of operations and technology there, said the DigiDrive II modular design makes use of a power drive block, interface board, and control interface which bear UL, CSA, and CE approvals from the factory. That saves original equipment manufacturers the time in the development cycle for getting agency approvals, Ansari said.

Meanwhile, OEMs can program velocity/frequency curves, acceleration ramp rates, and eight more parameters into the drive to tune it to a particular motor application, Ansari explained.

Marlow's product manager, Marian Dennison, said the Anacon drive can sit on any pump the company makes, up to 1 hp. Marlow will be offering whirlpool builders the controls packaged in two versions, one with a triple-mode massage and one with single mode. Common functions of the two versions include variable speed, dry-run sensor, and 30-minute shutdown.

One factor in Marlow's selection of the Anacon controller was its low level of inverter whine, Dennison said. The noise from other single-phase, variable-speed controllers Marlow tested was objectionable—not necessarily to the bather, who is immersed in a pool of rumbling water, but to the rest of a household having to hear the humming plumbing.

Gun boring is the conventional approach to machining engine blocks, according to Szuba, who directs R&D at Lamb. The boring bar is normally supported on both ends. While this arrangement keeps deflection low, it suppresses flexibility, he said.

With only one visible means of support, this cantilevered boring bar literally goes full bore.

To illustrate the point, consider an engine block that is used in two distinct applications, Szuba said. Suppose each application used a different cam, and each cam, a different bearing diameter. A conventional boring machine using end supports would need a change of tools before it could make the two hole sizes. Engine manufacturers, for this reason, would normally dedicate a single boring machine to each of the two applications, Szuba said.

With this in mind, engineers at Lamb developed a mechanical structure for a new boring machine that combines droop compensation with laser-guided tool path correction. The result is a machine that superimposes the accuracy of a simply supported boring bar upon the flexibility of a cantilevered arrangement, Szuba said. The Lamb machine bores a 25- to 75-mm hole anywhere within a 250-square-mm work zone without changeover or retooling, he added. Accuracy stays within 5 microns.

It is still a gun boring operation, Szuba said. A tool changer sits below the spindle for switching boring bar assemblies. Two servomotors adjust the machine along the y axis as the boring bar makes its way through an engine block. Droop compensation in this manner keeps consecutive bores running true.

The new machine eliminates any need for an operator to change tools between different fasteners, he said. Assemblies often use a variety of fasteners.

In a manual tool change, an operator installing fasteners may need to handle a workpiece several times. Handling increases the risk of damage to parts, Kelly said. In the case of circuit boards, scrapping them at the fastener-insertion stage of manufacturing is costly.

Through market research, Haeger discovered that seven seconds was about all the time press users would tolerate for tool changes. A typical insertion cycle runs 20 seconds, Kelly said. So the changer needed to be fast. As the tools weigh about a half-pound apiece, the changer had to be stout as well. Finally, the changer needed to hold tool positions within 0.002 inch, Kelly said.

Engineers at Rexroth Star of Charlotte, N.C., designed a new slide especially for the tool changer. Besides needing strength, quickness, and accuracy, a slender changer would keep the hardware from infringing on the work zone.

Rexroth engineers beefed up a stock slide with a heavier rail, then added a predrilled, low-profile baseplate by which it could be attached to the press.

To make speed—as much as 10 inches per second—the engineers specified a half-inch-diameter lead screw. A stepper spins the screw, moving the slide through its full 10-inch range. Three proximity switches keep tabs on overtravel and centering. An anti-backlash nut preloads the screw to take up thread slop during reversals.

To keep the slide clean, Haeger engineers mounted it upside down, then covered it with a neoprene-nylon bellows.

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