Model 635.XX Axial Extensometers

Transcription

1 m be certain. Model 635.XX Axial Extensometers Product Information A

2 Copyright information Trademark information 2014 MTS Systems Corporation. All rights reserved. MTS is a registered trademark of MTS Systems Corporation within the United States. These trademarks may be protected in other countries. All other trademarks or service marks are property of their respective owners. Publication information Manual Part Number Publication Date A October Axial Extensometers

3 Contents Introduction 5 Specifications 6 Safety Information 7 Safety Information Overview 7 Read all manuals 7 Personnel Qualifications 8 System Hazard Zones 8 Avoid Pinch and Crush Points 8 Installation 9 Zero Extensometer Output 9 How to Mount an Extensometer 10 About Quick Attachment Springs 10 About Metal Extension Springs 11 Extension Spring Table 12 About Elastic Bands Axial Extensometers 3

4 4 635 Axial Extensometers

5 Introduction This manual describes the MTS 635.xx axial extensometer family. Axial extensometers measure changes along the length of a specimen. Axial extensometers are suitable for a variety of static tensile testing applications. Accessories are available such as knife edges and attachment methods. Not all accessories are available for all models. 635 Axial Extensometers Introduction 5

6 Specifications Part Number Model Number 1 (Gage Length) 2 (Travel) 3 * 4 * F mm 25 mm mm mm F mm 10mm mm 77.5 mm F mm 25 mm 69.1 mm mm F mm 10 mm 61.5 mm 77.5 mm F mm 5mm 59.2 mm 77.5 mm F mm 5mm 39.6 mm 77.5 mm * Value rounded to nearest 1/10 mm. 6 Introduction 635 Axial Extensometers

7 Safety Information Safety Information Overview Extensometers are used to provide specimen feedback in material test systems. Operators using extensometers should be aware of the system level safety information. Test systems are designed to generate single-axis or multi-axial motions and forces simultaneously in a controlled laboratory environment and impart these motions and forces into a test specimen that is secured to the system. When you prepare to operate the system and during system operation, ensure the following: Do not use or allow personnel to operate the system who are not experienced, trained, or educated in the inherent dangers associated with high-performance servo hydraulics and who are not experienced, trained, or educated with regard to the intended operation as it applies to this test system. Do not disable safety components or features (including limit detectors, light curtains, or proximity switches/detectors). Do not attempt to operate the system without appropriate personal safety gear (for example, hearing, hand, and eye protection). Do not apply energy levels that exceed the maximum energies and velocities for the system design. Refer to the system specifications. Do not test a specimen that exceeds the minimum (if applicable) or maximum allowable mass. Refer to the system specifications. Do not use specimens that are combustible, flammable, pressurized, or explosive. Do not modify the system or replace system components using parts that are not MTS component parts or effect repairs using parts or components that are not manufactured to MTS specifications. Do not operate the system in an explosive atmosphere. Read all manuals Do not use the system in a test area where uncontrolled access to the test system is allowed when the system is in operation. Study the contents of this manual and the other manuals provided with your system before attempting to perform any system function for the first time. Procedures that seem relatively simple or intuitively obvious may require a complete understanding of system operation to avoid unsafe or dangerous situations. 635 Axial Extensometers Safety Information 7

8 Personnel Qualifications Do not allow unqualified personnel to perform any of the system maintenance, setup, or operating procedures. Operation and maintenance of the system by unqualified personnel can expose them and others to hazards that can cause damage to equipment and injury or death. The system maintenance, setup, and operating procedures should only to be performed by trained personnel. MTS offers training classes that provide the necessary skills training. System Hazard Zones Avoid Pinch and Crush Points The area around and including the test system is considered hazardous. Generally, hazards result from motions that occur during system operation. However, there are latent pressure, overturning, and settling/unexpected movement hazards that can occur prior to or after system operation, during specimen installation, or during maintenance and repair. The hazard zone includes the entire system and an additional area of at least 1 meter (3.3 feet) around the system perimeter. In addition, the hazard zone should be extended to include the optional hydraulic power source (when purchased) and any associated hoses, cables, and hardline. Whenever personnel enter this defined zone they should be outfitted with adequate and appropriate safety attire including hearing protection, safety glasses, hard hat, and safety shoes. Never wear loose fitting clothing when in the test area. Never enter the test area when hydraulics are on. When possible, install the extensometer on the specimen before installing the specimen in the grips. Pinch points exist between the parts of the grip or fixture that contact the specimen. Be aware of these pinch points when installing a specimen or working around the grip or fixture during test setup. High forces generated when grip pressure is activated can pinch, cut, or crush anything in the path of the grip/ fixture specimen contact area and cause serious injury. Stay clear of any potential pinch points. A crush point exists between the grips. Whenever possible, use tongs or similar tool when handling the specimen during specimen installation. Never allow any part of your body to enter the path of machine movement or to touch moving machinery, linkages, hoses, cables, specimens, and so forth. These present serious crush points or pinch points. 8 Safety Information 635 Axial Extensometers

9 Installation This section describes how to mount the extensometer to a specimen and zero the extensometer output. Contents Zero Extensometer Output 9 How to Mount an Extensometer 10 About Quick Attachment Springs 10 About Metal Extension Springs 11 Extension Spring Table 12 About Elastic Bands 14 WARNING Handling the extensometer while it is selected as the active control mode can cause the actuator to move unpredictably. Unpredictable actuator movement can cause personnel injury or damage to the test equipment. Ensure that the extensometer is not active when installing it to a specimen. Zero Extensometer Output The shield of the Extensometer (pin E for PT style connector and pin A for Amphenol style connector) must be connected to the controllers chassis ground. This is typically accomplished by using a metal or metalized plastic connector and a braided shielded cable from the controller to the Extensometer cable, see MTS cable part numbers xx PT style or xx Amphenol style for an example. Typically, you would zero the extensometer output as follows: 1. Zero pin installed. 2. Extensometer attached to the specimen with attachments properly adjusted. 3. Remove the zero pin with a rolling action taking care not to slide the knife edges on the specimen while the zero pin is being removed. 4. Zero the electronics at the specified initial gage length. The purpose of zeroing the extensometer output is to identify the starting position of the extensometer to the system controller. An extensometer usually needs to be zeroed (at least checked) after it has been installed. For example, suppose the extensometer is installed and is a bit off from its calibrated zero position. The controller can be programmed to accept the current output from the extensometer as the zero output. 635 Axial Extensometers Installation 9

10 How to Mount an Extensometer See your controller manual for information on establishing the extensometer zero output signal. The electrical output of the extensometer is adjusted so that zero strain equals zero volts output. Axial extensometers can be installed using quick attachment springs, extension springs, or elastic bands. The quick attachment springs are anchored in one of several holes to accommodate various specimen sizes and clip onto the specimen. Installing the quick attach springs in the various holes also controls the hold-down force between the knife edges and specimen contact. Extension springs and elastic bands mount the extensometer to a specimen in the same way. Prerequisites The extensometer must be configured with the appropriate attachments for the specimen and test. The extensometer must also be calibrated for use. Every range defined for the extensometer should be calibrated. Procedure When installing an axial extensometer on a specimen, the arms of the extensometer must be in the zero reference position. About Quick Attachment Springs 1. Zero the arms of the extensometer. This can be accomplished using the zero pin. 2. Hold the extensometer so that its knife edges contact the specimen. 3. Secure the upper arm around of the extensometer the specimen. If you are using an anchored spring mount, clip the spring around the specimen. If you are using extension springs or elastic bands, connect one to the hook attachment of the upper arm. Use a small utility hook to grab the other end and pull it around the specimen to the other attachment hook. 4. Repeat Step 3 for the lower arm of the extensometer. 5. Zero the extensometer s output. A. Remove the zero pin. B. Check the extensometer output at your controller. C. If necessary, zero the extensometer output at your controller. Quick attachment springs hold the extensometer onto the specimen with a pair of special springs that clip around the specimen (see the following figure). 10 Installation 635 Axial Extensometers

11 Quick attachment springs can be adjusted to accommodate different specimen thicknesses. They can be adjusted by sliding the spring in or out of the attachment adapter or by anchoring the spring in a different hole on the attachment adapter. Note If the specimen dimension is outside the range of the quick attachment springs, other attachment methods must be used, such as metal extension springs or elastic bands (an assortment is provided with the extensometer), half disks, or wireform springs. About Metal Extension Springs Metal extension springs may be used for testing throughout the temperature range of the extensometer. The metal extension springs are stainless steel with an outside diameter of 3.18 mm (0.125 in). The spring wire is 0.41 mm (0.016 in) thick. More than one spring can be connected end-to-end to accommodate large specimens. 635 Axial Extensometers Installation 11

12 Spring length is selected based on specimen size and required contact force. The recommended contact force is approximately 600 grams. Greater contact force will provide a more secure attachment under conditions where slippage may occur such as operating at high cyclic frequencies. The knife edges can damage the specimen at high contact forces. Less contact force will reduce the possibility of damage to soft specimens; however, the possibility of slippage increases. Round specimens An extension spring attachment method can be used for large and small diameter round specimens. It can be used by all axial extensometers. One spring can be used on smaller diameter specimens. Two springs can be used for larger diameter specimens. Flat specimens An extensometer can be mounted to a flat specimen with extension springs using a disk or wireform attachment. When using a wireform attachment, it is necessary to replace the attachment adapters with knife edge hold-downs. Extension Spring Table The wireform attachment is an optional accessory for wide, flat specimens. Use the following table to determine which extension spring to use for a specific specimen diameter. Depending on the specimen diameter, you can select between different spring lengths and specimen contact forces. The table shows the recommended spring lengths for a specific specimen diameter and the contact force on the specimen for each spring length. 12 Installation 635 Axial Extensometers

13 Note The recommended contact force is approximately 600 grams. Spring Free Length mm (in) Free Length Measurement for Single Spring Free Length Measurement for Multiple Springs 12.7 (0.50) 15.9 (0.62) 19.0 (0.75) 22.2 (0.87) 25.4 (1.00) 28.6 (1.12) 31.8 (1.25) 34.9 (1.37) 38.1 (1.50) Specimen diameter mm (in) Contact Force (grams) 2.0 (0.08) (0.12) (0.16) (0.20) (0.24) (0.28) (0.32) (0.35) (0.39) (0.43) (0.47) (0.51) (0.55) (0.59) (0.63) (0.67) (0.71) (0.75) (0.79) Axial Extensometers Installation 13

14 About Elastic Bands Elastic bands are commonly used for testing at near room temperature. The contact force may be varied by the cross-section size of the elastic band and its overall length. Elastic bands can be used by all axial extensometers. Elastic bands (rubber bands) of the type provided with the extensometer are available from stationery supply stores. Orthodontic elastic bands may also be used and are available from medical supply houses. Round specimens An elastic band attachment method can be used with round specimens. Each knife edge requires a band to secure it to the specimen. Flat specimens An extensometer can be mounted to a flat specimen with elastic bands using a disk or wireform attachment. When using a wireform attachment, it is necessary to replace the attachment adapters with knife edge hold-downs. Contact force Determining the specimen contact force when using elastic bands is difficult. Greater contact force will provide a more secure attachment under conditions where slippage can occur such as operating at high cyclic frequencies. The knife edges can damage the specimen at high contact forces. Less contact force will reduce the possibility of damage to soft specimens; however, the possibility of slippage increases. 14 Installation 635 Axial Extensometers

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