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| Specifications for the TTD Series of |
| Tension/Compression Testing Machines |
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| Revised: Feb. 3, 2002 |
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| Introduction |
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| The TTD Series of bench mounted tension/compression testing machines presently includes six different capacities. These include the following models and their ratings: |
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| TTD-65KN (65 kN / 15,000 lb Capacity) |
| TTD-5OKN (50 kN / 11,000 lb Capacity) |
| TTD-35KNI (35 kN / 8,000 lb Capacity) |
| TTD-25KN (25 kN / 5,500 lb Capacity) |
| TTD-10KN (10 kN / 2,200 lb Capacity) |
| TTD-5KN ( 5 kN / 1,100 lb Capacity) |
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| Figure 1 shows the Model TTD-5OKN version of the testing machine with the Optional polycarbonate safety shield in place. All other models of the TTD series are of similar design except the TTD-35KNI. Figure 2 shows the special design of the TTD-35KNI which has an integral Lower Compression plate and Upper Compression platen for performing compression tests on large parts. |
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| The machines in the TTD series feature a double ball screw driven loading crosshead which travels vertically up and down between the upright ball screws. The lower ends of the ball screws are mechanically coupled to a variable speed DC servo motor with tachometer feedback for accurate closed loop speed control. The crosshead motion is controlled by front panel mounted Up/Down and Stop/Start switches. The test speed is accurately set between 0 - 100 % of the maximum speed using a front panel mounted 10 turn vernier control or 3 digit speed control selector. Figure 3 shows the front panel view of the TTD-5OKN with the standard setup of control switches and speed control vernier. Figure 4 shows the closeup view of the TTD-35KNI with the 3 digit speed control selector and the optional crosshead position indicator. Additional details on the crosshead position indicator are provided in the Options Section. Figure 5 is a closeup view of the digital display used for monitoring the test load and for indication of peak load at test completion. |
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| The major dimensions of the models in the TTD series are shown in Figure 6. Figure 6 also shows the main part designations and includes details on the TTD-35KNI version which has integral Upper and Lower Compression Platens for performing compression tests. Other systems may include other types of tensile and compression grips or specialized test fixtures. |
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| Motor Control System |
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| The main components of the TTD series motor control system consists of a servo amplifier, a DC power supply for powering the servo amplifier, and a DC servo motor with a tachometer mounted on its rear shaft. The servo amplifier is a four quadrant regenerative operation high switching frequency motor controller which is operated in tachometer feedback (speed control) mode. The high frequency (33 kHz) operation results in a very compact size, high efficiency, and accurate speed regulation when a tachometer is utilized for closed loop control. Operation is possible to as low as 2% of the maximum rated speed at reduced load capacity. |
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| The electrical circuitry to control the crosshead consists of the following elements. The Up/Down selector switch determines the movement direction of the crosshead when the motor is running. The Stop/Start selector switch will cause the motor to begin rotating and moving the crosshead at the speed indicated by the Speed Control setting. The lower limit of the speed for full capacity operation of the TTD series of testing machines is 5 mm/min (0.2 in/min) although the machine may be operated at a reduced load capacity below this low speed limit range. |
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| Load Display System - General Information |
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| The microprocessor display board utilizes a precision DC conditioner for the functions of excitation and amplification of the load cell signal. In addition, the system allows for the scaling and display of the calibrated load cell signal in one of three Operator chosen Engineering Units, continuous monitoring of the maximum compressive and tensile loads applied to the load cell, monitoring the status of the upper and lower crosshead travel limit settings, and the operation of taring or zeroing of the load cell if any changes in the grips or test setup have been made. The load cell signal is measured using a 12 bit A/D converter whose sampling rate is controlled by an on board microprocessor. The microprocessor also serves the |
| functions of monitoring the front panel push button switches, monitoring the test maximum and minimum load cell signal, and monitoring and indication of the load cell capacity limits. |
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| Detailed Description of Load Display System |
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| The load display system was designed to overcome some of the shortcomings of the various displays which are commercially available for amplification and display of load cell signals. These displays typically calculate and display the maximum and minimum loads at the same low speed rate of approximately 3 / second (ie. 3 Hz). The ATM display externally updates at approximately 3 Hz but internally updates at a conversion rate of over 800 Hz. The high speed conversion rate ensures that peak loads are accurately calculated at the time of sample failure which is usually a high speed event. Displays which convert at a rate of approximately 3 Hz. tend to inaccurately calculate the failure load in situations of rapid load changes. |
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| The ATM display board has also been designed to allow Operator input of lower load limits than the load cell capacity for test situations where a test is to be stopped after a preset test load has been applied. If the preset load limit is reached the crosshead motion will stop. The load can then be decreased by reversing the test direction. The Operator can set the display to indicate load in Units of lb, kg, or N for test applications requiring different testing Units. The Operator may also tare the load cell to zero out a, non-zero load reading due to load grips setup changes or during the initial system warmup. |
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| Main Display Function Kev Descriptions |
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| A) Single Key Input Operations |
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| The single key input operations are described as follows: |
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| a) Cal Check |
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| A quick calibration check of the load cell may be performed by use of this key. Load cells provided by ATM are of a full Wheatstone bridge type which utilizes four strain gauges for measurement of the load. Pressing the Cal Cheek switch places a resistor in parallel with one of the four strain gauges which results in an unbalanced bridge and a known load cell output reading. The Operator can then |
| compare this reading to that taken when the load cell was initially calibrated. |
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| b) Set Units |
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| The Set Units key switch allows the Operator to select between the Units lb, kg, or N for load display. Pressing the Set Units key will cause the red light emitting diode (LED) next to the indicated Unit to turn on and the displayed reading to be updated to the selected Unit. |
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| c) Max |
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| The Max key switch is used to display the internally stored maximum tensile load or smallest compressive load (ie. closest to zero load) since the Clear button was last pressed. This load is calculated by sampling the load cell signal at over 800 Hz. The load will be displayed in the Engineering Unit which has been selected. |
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| d) Min |
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| The Min key switch is used to display the internally stored maximum compressive load or smallest tensile load (ie. closest to zero load) since the Clear button was last pressed. This load is calculated by sampling the load cell signal at over 800 Hz. The load will be displayed in the selected Engineering Units. |
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| e) Clear |
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| The Clear key switch is used to reset the display to start recording the maximum and minimum load cell readings. This switch would typically be pressed before the start of a test to ensure that the correct Maximum and minimum load readings have been stored during a test. |
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| f ) Tare |
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| The Tare key switch is pressed to zero the load cell if a change in the loading grips arrangement has been made or if the system electronics are in the warmup period. This is a software tare and is not recorded by the microprocessor display board memory when the AC power switch is turned off. |
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| B) Combined Key Operations |
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| The four combined key operations are used to change the Operator settable load limits. If these limits are exceeded during a test, the crosshead movement will stop and an Error messsage will be displayed. If the maximum load limit or the upper crosshead travel limit setting is reached the Error message E HI will be displayed. If the minimum load limit or the lower crosshead travel limit setting is reached the Error message E LO will be displayed. The combined key operations to change the load limits are described as follows. |
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| a) Max and Clear |
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| Simultaneously pressing and holding the Max and Clear key switches will increment the Operator settable maximum load limit from the present setting. |
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| b) Max and Tare |
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| Simultaneously pressing and holding the Max and Tare key switches will decrement the Operator settable maximum load limit from the present setting. |
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| c) Min and Clear |
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| Simultaneously pressing and holding the Min and Clear key switches will increment the Operator settable minimum load limit from the present setting. |
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| d) Min and Tare |
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| Simultaneously pressing and holding the Min and Tare key switches will decrement the Operator settable minimum load limit from the present setting. |
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| Optional Features |
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| Additional features may be added to the TTD Series of machines for special applications. Some of these options are listed as follows: |
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| a) Safety Shields for Front and Rear (Option TTDxxxx.SAF) |
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| The TTD series machines may be supplied with clear safety shields for the front and/or rear working area of the systems. The safety shield package consists of two side panels and two front hinged panels of 3/8 in (9.5 mm) thick clear polycarbonate sheet. This design ensures a large enclosed working distance for specialized setups. The side panels are approximately 4 in (10 cm) wide and do not open. The hinged doors are secured in place by two sliding bolts. |
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| The safety shield package includes two hinged door panels, two side panels, and mounting hardware. A complete package is used to enclose each of the front and rear working areas of the system. Price of each package includes factory installation of the safety shields on the machine when ordered with the TTD series machine. |
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| b) Bellows Covers on Ball Screws (Option TTDxxxx.BSC) |
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| The standard TTD series machines include upright sheet metal protective panels around three surfaces of the ball screws. For dusty environments, ATM can supply the TTD machines with bellows over the ball screws to prevent dust from coating the ball screws which may cause premature wear. This option is a factory installed modification and should be ordered with the system. |
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| c) Crosshead Display Option (Option TTDxxxx.CD) |
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| For applications where the crosshead position must be known during the test, the TTD Series machines may be ordered with the crosshead display option. This option involves modifying the system with a Crosshead Display meter mounted on the front panel and mounting of an encoder which is belt driven off one of the ball screws. The crosshead display is a scaleable pulse counter which is setup to display the pulses in units of inches. The display features front panel mounted switches for setting the scale factor and for zeroing the display at a given crosshead position. The meter also has the capability of outputting an analog voltage signal to the rear mounted Crosshead Position Output BNC connector for monitoring the signal using an external meter or for use with the following Upgrade kit. |
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| d) Computer Software Upgrade Kit (Option Model TC-100) |
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| For enhanced operation of the TTD Series machines, a special version of our Model TC-100 Tension/Compression software package which is used with our TTS Series of computer controlled testing machines is available for the TTD Series. The complete Upgrade Kit consists of the TC-100 Software package for performing tension and compression tests and a 12 bit A/D board for monitoring the load cell signal and crosshead position if the crosshead position option is available on the machine. The TC-100 Upgrade Kit is used to graphically display on a computer monitor the test in real time on an X-Y plot. Data points are plotted during the test and a data file may be stored to the computer hard drive at test completion. One page summary reports of the test can also be printed for record keeping purposes. |
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| This option requires use of an IBM PC type 486 or Pentium based computer running a Microsoft DOS 5.0 or higher operating system or Windows95 or Windows98. The software will not function under WindowsNT or Windows2000. A Demonstration diskette of the features in this software package is available. Please contact ATM for information on obtaining a copy of the Demonstration package. |
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| In addition to the listed options, ATM can provide other modifications to the standard machines to accommodate specific requirements. Some of these options include safety door mounted limit switches to shut off the motor, increased working distance between the ball screws, longer travel length, very low speed range for ultra low speed control applications, and others. Please contact us with your additional requirements. |
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| Accessories |
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| A wide range of accessories such as test grips and fixtures can be provided by ATM to allow testing of many different sample types or customer products. The following lists some of the items that are available from ATM. |
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| a) Extensometers |
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| ATM can provide linear, diametral, biaxial, non contact laser types and elevated extensometry equipment for most applications. They are available in a wide range of deflections and temperature ranges for use with the ATM line of software and test equipment. Please contact ATM for your specific requirements for extensometry equipment. |
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| b) Material Testing Grips |
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| An extensive line of material testing grips such as wedge loading tensile grips, clevis grips, compression plates, 3 and 4 point bending fixtures, and others can be provided. Special high temperature grips for ceramics testing are also available. ATM can also custom design test grips or test fixtures to test component parts. Please contact ATM for all your test fixture requirements. |
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| c) High Temperature Test Ovens |
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| ATM can supply split tubular or box type testing ovens in a range of temperature capabilities up to 1,200 F and a very high temperature line for materials testing up to a maximum temperature of 2,800 F. These models mount on swing arms which will attach directly to an upright post mounted on the TTD Series machines for this application. When not in use, the swing arms permit the oven to be swung completely out of the way of the load train. |
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| d) Environmental Chambers |
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| Low temperature environmental chambers with temperature and/or humidity control are also available. These chambers are of mainly stainless steel construction and are designed with the same accessibility as the test ovens. Depending on the size of the chamber, they are either mounted on the ATM TTD Series machines by use of swivel arms or are separately attached by use of other means such as a roll out platform. |
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