Three 75-kilowatt vector drives in a master/slave configuration control the reel that feeds 12-inch-diameter steel pipes.

The drives are serving what conventionally would have been a hydraulic application, bringing the benefits of the availability of full torque at all speeds and standstill for the control of a massive 18.3-meter reel for the feeding of steel pipe up to 30 centimeters in diameter. The pipe is loaded in 500-meter lengths, which are welded together on the shore and wound onto the reel.

The drive system was reconfigured for this particular vessel. The system comprises three 75-kilowatt drives, complete with software to provide a load-sharing and master/slave changeover facility.

The units work in master/slave configuration—the master unit running in speed control and the other two in torque control as helpers. Effectively, all three work as one big drive acting on a peripheral chain drive. Although the three drives are set up to share the load, if one should fail, the system must continue to run with minimal disruption. In the event the master unit fails, the second in line is reconfigured in milliseconds to run in speed control, with no discernible jolt in the feed.

During normal laying operation, the drives running in torque control are in regeneration mode, producing a considerable amount of energy that has to be dissipated. Two large water-cooled resistors are used for this purpose.

Tapered-hex rollers silently convey up to 7,500 packages per hour and resist the premature wear that usually plagues high-speed rollers

Sandvik has standardized the Taperhex roller for its linear singulator flow controller. The spring-loaded, tapered-hex shafts of the roller lock into the conveyor frame mounting holes to eliminate all possible movement in any direction between the shaft and frame. In one component of the singulator, the rollers are 88 inches long and 2.5 inches in diameter; they are installed on an angle, conveying the packages toward one side. Successive sets of rollers are motor-driven to increase package flow from an initial entrance speed of 200 feet per minute to 400 feet per minute at the end. The combination of skewed rollers and increasing speed increments creates space between packages, so other packages can merge into alignment and form a straight line.

Another component—the side-by-side mover—has three parts: a 6-inch-wide high-friction belt, a skewed-away section of the 16-inch-long rollers, and an in-line section of 4-inch-long rollers. In this section, the width of the friction belt is the same as the narrowest package being handled. Packages that come in contact with the belt are transported through, single file, at 400 feet per minute. Others are diverted to the recirculating slide of the third component, the recirculation conveyor.

When Sandvik first identified roller rattle as a problem, the company had explored shaft-end sleeving but considered that ineffective. It also examined bolting the rollers into place, which would require costly maintenance for its customers.

The Taperhex rollers pop into the conveyor side frame in the same manner as conventional spring-loaded rollers. The self-adjusting tapers wedge tightly in place, regardless of the condition of the mounting holes. The tapered shafts seat tightly in worn holes as well as rounded hex holes, preventing further wear.

The springs are used to increase downward force to planter-row units and improve seed placement in tough soil conditions. They replace steel springs found on conventional agricultural equipment.

The springs, pressurized by a small compressor on the planter frame, generate up to 400 pounds per square inch for proper soil penetration even under adverse conditions. A benefit of the pressurized springs is that they can be adjusted automatically by resetting the pneumatic force on all units. By contrast, conventional steep springs would have to be adjusted individually. Also, the downward force can easily be removed from splitter-row units on narrow-row planters, which makes it easier to adjust for row widths.

Dynapace's customers typically operate the conveyors continuously; therefore, they must work reliably all the time with little maintenance. To drive the transport belts of the conveyors—which in turn create linear motion, equipment rotations, and elevation changes—the company uses permanent-magnet dc gear motors from Bodine Electric Co. in Danville, Ill. Dynapace designed its conveyors with these motors in mind, citing low maintenance, high torque, small size, and consistent motor speed.

When the Whopper Chopper cut-off knife from United Tool Co. (UTC) in Wabash, Ind., needed a controller that would help ensure consistent, accurate cuts, the company chose a drive from Force Control Industries (FCI) in Fairfield, Ohio.

This closed-loop position-control system guides a 255-pound, 96-inch wide knife assembly precisely through a 32-inch stroke

UTC's knife cuts units of fiberglass insulation, or bats, at 60 to 80 chops per minute. The accuracy of each bat is critical to maintaining product quality and minimizing waste. However, accuracy with the dry-friction clutch/brake and open-loop control system that the company had used was difficult to achieve when wielding a 255-pound, 96-inch-wide knife assembly through a 22-inch stroke.

The knife's accuracy requires the crank linkage to stop in exactly the same position in each cycle: 5 degrees after top center. To control brake actuation and deal with loss of accuracy, the manufacturer had used a device known as a rototimer, which required that machine operators adjust the actuation point to hit the stop position. To do this, the machine had to be stopped and the operator needed two wrenches to make the adjustment—a time-consuming, imprecise process.

To reach higher production speeds and accuracy, UTC purchased an oil-shear clutch/brake and closed-loop position-control (CLPC) system from FCI. "The lower inertia of the new clutch/brake has cut our cycle time to about 300 milliseconds, rest to rest," said UTC vice president Troy Poland. "The closed-loop control stops the drive shaft within about 2 degrees every time, virtually eliminating variances in product length."

The multidisk oil-shear clutch/brake is well suited for the high cycle rate and high torque required by the knife. The air-actuated clutch/brakes transmit torque by shearing automatic transmission fluid between multiple friction disks. The fluid absorbs the heat of engagement and dissipates it through the housing. This results in stable torque transmission performance, even at varying speeds and temperatures. The recirculating oil between friction surfaces greatly reduces wear, extending service life.

The CLPC enables oil-shear clutch/ brakes to index with servolike accuracy, at rates of 20 to 30 cycles per minute up to more than 600 cycles per minute. The control is a dedicated, reactive, error-compensating clutch/ brake control for precision indexing. Designed for quick reaction time and repeatable stopping with oil/shear drives, it reportedly outperforms more-expensive programmable-logic-controller-based systems and approaches servo accuracy for a lower cost than servos.

The control system takes data from an incremental encoder—usually on the clutch/brake or reducer output—to record how many encoder counts (if any) it undershoots or overshoots a programmed stop position. The control's software uses a running average of any error to advance or retard the brake's trigger point constantly to hold the stop position. Accuracy of one encoder count from absolute position is achievable at cycle rates of 600 cycles per minute, which is equivalent to ±3 degrees at 1,800 rpm.

After looking to purchase the gears for metalworking equipment from an outside vendor, Ann Arbor Machine Co. (AAM) in Chelsea, Mich., chose to mitigate the effects of long turnaround time by bringing gear manufacture in-house.

A hobbing machine produces gears with diameters ranging from 0.25 to 5 inches; an optional modification increases the maximum gear size to 8 inches.

AAM purchased a Phoenix 125GH six-axis computer-numerical-controlled gear-hobbing machine from The Gleason Works Co. in Rochester, N.Y. For absolute rigidity, the machine uses an all-cast-iron base construction with four completely solid lengthwise walls and a minimum number of openings to produce quality gears consistently. Also, bob overhang is only 7.5 inches, and a patented hob head permits low work arbor heights.

To streamline production, most gears have the same pitch and pressure angles. Gears manufactured are usually straight spur gears, and some have internal splines. All gear cutting is done with 8-inch-long hobs except for straight-sided splines, which are done with 3-inch hobs. Gear blanks are machined in-house.

Software enables the user to program the system for a new gear in approximately 5 minutes. A standard storage capacity exists for up to 100 previously developed part programs. The controller allows automatic setup and control of axial feed, radial feed, hob position, hob speed, and hob swivel-angle setting. To change hobs, the operator presses two buttons on the hob head to chuck and dechuck the tool.

Before purchasing the Phoenix, AAM had considered purchasing a used hobbing machine. However, the machines the company looked at didn't match the versatility, precision, or quality of the new machine. "If we had bought a used machine," said Bob Turke, head of AAM's Gearing Department, "it never would have kept up with all the in-house work. We're very satisfied that we made the right decision to purchase the new machine."

Since implementing the machine, gear turnaround times have been cut from months to hours. Furthermore, the cost per gear was equal to or slightly lower than those from the outside vendor.

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