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Spin Test Equipment Products

Data Acquisition Systems

We design, build and install complete systems for your data acquisition needs, from providing and installing instrumentation to setting up signal conditioning and installing custom built monitoring and controls systems. This eliminates the additional costs, liability issues, and time delays associated with multiple vendors accomplishing various portions of the completed task.

Spin Test Systems

Test Devices designs and manufacturers spin test systems and drive turbines for spin pits. A wide variety of sizes are available from as small as 12" to over 100" rotor capacity. Applications range from production proof testing to sophisticated development testing of complex rotor systems. Test Devices can supply the complete system or a portion of the product custom designed for a particular application. Following is a brief description of a generalized spin test system that includes containment, console and vacuum/auxiliary skid.

Figure 1

Spin Pit Test Chamber

The containment system is purposefully over-designed to insure elastic containment in case of a burst, and has the ability to contain even higher energy rotors that may be designed in the future (using higher strength materials and operating at higher speeds).

Cross Sectional View

Figure 2
Spin Test System Elevation

The above figure is an elevation drawing of a spin pit chamber composed of five major elements that are carefully designed for safe operation and long life.

Casing

The casing is fabricated from high strength steel and is intended to enclose the entire test pit and sustain an airtight vacuum. The casing is generously oversized from the containment cylinder to allow the inner liner to grow elastically (if necessary as a result of an extremely high energy burst) with no effect on the system’s internal vacuum.

Cover and Lid

The cover is constructed of thick, high-strength alloy steel, and is bolted to the casing with one-inch dia. grade 8 hardware. There is an air tight o-ring seal between the casing and the cover, and cover is removable for inspection or for access to the entire chamber.

The lid is specially designed to pilot into the cover’s o-ring seal and accommodate the drive system and instrumentation junction boxes that sit atop the spin pit. The lid opening is held in place by four servo-actuated, high-strength cover locks (lid dogs). The lid dogs are a mechanical safeguard to insure the lid remains in place in the event of a high-speed impact. They also have an automatic closure and interlocking system to prevent operation of the spin pit without the locks in place (i.e. the lid dogs cannot be opened while the drive turbine is rotating).

spin pit lid

Figure 3
Spin Pit Lid

Lid Elevator

In a vertical spin pit the test article is hung vertically from a spindle that is attached to the drive system mounted on the top of the lid. The elevator system is designed to offer quick and convenient manipulation of the test article in and out of the spin pit, and the air float counter-balance aids in the removal of the test article from its attachment to the spindle and drive. This is critical for high-throughput production systems, especially when large or heavy test articles are involved. Once the lid and rotating element are clear of the top of the pit, the elevator system can rotate the assembly to as much as 180 degrees in either direction. The entire system is hydraulically powered.

Part Handling and Optional Air Float Counterbalance

For smaller parts, a simple but effective technique for part handling is to use a wheeled cart with swivel casters. A partially inflated inner tube can be placed on top of the cart; and the test piece should rest on the inner tube. This soft mounting arrangement makes it easy to align the spindle and socket. A cart with a hydraulic lift mechanism can also be used. For larger parts an optional Air Float Counter-balance can be installed on the side of the spin pit casing for test piece installation. This system allows easy coupling and uncoupling of parts into the drive system. The centerline of the counterbalance is located exactly on the centerline of the lid when rotated to the counterbalance position.

Lead Brick and Alternate Material Liner

Test Devices uses a soft lead liner inside the primary containment (forged steel armor liner). The lead:

Catches parts before they reach the cover;
Prevents formation of explosive metal dust ( an especially serious problem for rotors containing aluminum and/or magnesium);
Spreads out the time of force application (mv = F*Dt) which significantly lowers the impact force; and
Damps resonant modes during a burst that can double the stress in the primary containment.

brick pit

Figure 4
Lead Bricks and Retention Ledge

System Control and Monitoring Console

The control console is specifically designed to be the most productive in the industry. Listed below are its major elements and features.

Multi-function digital tachometer, including fast response over-speed trip. The tachometer displays six digits and includes a high-speed computer communications interface. The tachometer is a microprocessor based instrument developed by Test Devices Inc. specifically for spin test applications. It includes dual sensor input with crosscheck comparison to protect against sensor failure, as well as quadrature detection for sensing the rotation of direction of the drive. The overspeed trip system includes a relay for direct control of the system safety trip valve.

Liquid-damped pressure gauges indicating air supply, drive nozzle, brake nozzle, and oil pressure.

Electronic vacuum gauge with limit relay for safety interlock.

Spin stability monitor (vibration meter) using a non-contact proximity probe to measure the vibration of the test piece mounting arbor.

Fig 5 - Console

Figure 5
Modern Control Console for Development Testing. Includes touch screen operator interface, heater controls, LCF capability, tachometer and vibration system.

Turbine speed control system for accurate regulation of steady-state test protocols, including proof tests, burst tests, over-speed tests, etc. Acting in conjunction with the high-speed servo pressure regulating valve, the controller regulates turbine speed within 0.2% of set-point throughout the duration of a test.

High-performance, turbine speed regulating valve assembly, including 50 millisecond response time control servo valve, and high capacity slave regulator valve to control airflow to the turbine.

Touch-screen operator control display. The display is a software and hardware system built on a Pentium computer with SVGA high-resolution color graphic display. The computer used is a standard model, easily maintained by local resources. Operator control is through a touch-screen for simple operation. The operator controls the equipment by touching buttons displayed on the video screen.

Each rotor to be tested in production can be listed on the "setup" page with speed and test duration. The operator sets up the system by touching a softkey labeled with the rotor identifier code, and the machine is then automatically configured to perform the proper test for that rotor. Rotor identifier codes, speeds, and test duration are easily changed by the supervisor through the use of a password which gives access to the data to be changed.

Laser Printer - The laser printer is used to make a permanent record of each test by printing an image of the operator control screen at the end of the test. A data block on the screen allows the operator to input the serial number of the rotor which has been tested, then the document can be printed and stored as a permanent part of the production record for each rotor. The printer can also be used for data logging of temperature, speed and cycle number during low cycle fatigue development testing.

Non-interruptible power supply - A battery-backed inverter power supply is installed in the system to operate all controls and instruments during a power failure. The capacity of the battery backup system is sufficient to maintain operation for 10 minutes after failure of the mains supply. If a test is being run in automatic mode, power failure will cause application of the brake until the rotor has stopped or until main air supply is exhausted.