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JJG 139-2014 English PDF (JJG139-2014)

JJG 139-2014 English PDF (JJG139-2014)

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JJG 139-2014: Verification regulation of Tension, Compression and Universal Testing Machines

This Regulation is applicable to the initial verification, subsequent verification and in-use inspection of tension, compression and universal testing machines.
JJG 139-2014
JJG
NATIONAL METROLOGY VERIFICATION
REGULATION OF THE PEOPLE REPUBLIC OF CHINA
Tension, Compression and Universal Testing Machines
ISSUED ON: AUGUST 01, 2014
IMPLEMENTED ON: FEBRUARY 01, 2015
Issued by: General Administration of Quality Supervision, Inspection and Quarantine
Table of Contents
Introduction ... 5
1 Scope ... 7
2 Normative References ... 7
3 Overview ... 7
4 Metrology Performance Requirements ... 8
4.1 Level of testing machines ... 8
4.2 Co-axiality of the clamping device for the tensile test ... 8
4.3 Zero drift ... 8
4.4 Displacement measuring device ... 9
4.5 Deformation measuring device ... 9
4.6 Noise ... 9
5 General Technical Requirements ... 9
5.1 Appearance ... 9
5.2 Afterburner system ... 10
5.3 Force measuring system ... 10
5.4 Electrical equipment ... 10
5.5 Safety protection device ... 10
6 Measuring Instrument Control ... 11
6.1 Verification conditions ... 11
6.2 Verification items and verification methods ... 11
6.3 Processing of verification results ... 19
6.4 Verification period ... 19
Appendix A Co-Axiality Inspection Specimen ... 20
Appendix B Original Records for Verification of Testing Machine ... 21
Appendix C Verification Results in the Inner Page Format of Verification Certificate of Testing Machine ... 23
Verification Regulation of Tension, Compression and
Universal Testing Machines
1 Scope
This Regulation is applicable to the initial verification, subsequent verification and in-use inspection of tension, compression and universal testing machines (hereinafter referred to as testing machines).
2 Normative References
This Regulation cites the following documents:
JJG 762 Extensometer
GB/T 2611-2007 General Requirements for Testing Machines
GB/T 3159-2008 Hydraulic Universal Testing Machines
GB/T 16825.1-2008 Verification of Static Uniaxial Testing Machines - Part 1: Tension/Compression Testing Machines - Verification and Calibration of -he Force- Measuring System
For dated references, only the dated version applies to this Regulation; for undated references, the latest edition (including all amendments) applies to this Regulation. 3 Overview
Tension, compression and universal testing machine is a testing machine that applies force value mechanically or hydraulically; it is mainly composed of an afterburner system, measuring system, safety protection device, etc. It is a testing machine that measures the mechanical properties of materials. It is applicable to the tension, compression and other mechanical property tests of the metallic and non-metallic materials and components; with the help of accessories, it can also be used for bending-proof, bending, shearing and peeling tests, etc. 5.2 Afterburner system
5.2.1 The rack of the testing machine shall have enough test space to facilitate the loading and unloading of specimens, specimen fixtures, standard force gauges and other auxiliary devices. 5.2.2 The test force applied and removed by the testing machine shall be stable, without shock and vibration. The friction force between the oil cylinder and piston of the hydraulic testing machine, under no-load conditions, when the working piston runs within the effective stroke, the change of the indication value of the test force shall be less than 1/2 of the absolute value of the allowable error of the lower measurement limit.
5.2.3 The holding time of the test force shall be no less than 30s. During this period, the variation range of the force indication shall not exceed 0.2% of the maximum force value of the testing machine.
5.3 Force measuring system
5.3.1 The resolution r of the analog indicating device shall be the ratio of the width of the pointer to the distance between the centers of two adjacent scale lines (scale interval). 5.3.2 Resolution of digital indicating device: start the testing machine; under zero load condition, if the change of the indication value is no more than one increment, the resolution r shall be considered as an increment; if the change of the indication value is greater than one increment, the resolution r is half of the range plus an increment.
5.3.3 The computer display or digital indicating device shall directly display the force value in the unit of force; and shall be able to display the zero point and maximum value of each indication range and the direction of the force (for example: "+" or "-"). 5.4 Electrical equipment
The electrical equipment of the testing machine is safe and reliable, and there is no leakage phenomenon. The insulation resistance between the power cord and the chassis shall be greater than 1M??.
5.5 Safety protection device
5.5.1 When the applied test force exceeds 2% to 5% of the maximum test force of the testing machine, the safety device shall act immediately to stop the testing machine from adding force. 5.5.2 When the moving chuck of the testing machine runs to the limit position of its working range, the limit device shall act immediately to stop the movement.
corresponding accuracy) for verification. During verification, firstly clamp the test specimen on the chuck and apply an initial force of about 1% of the maximum test force of the testing machine; adjust the zero point of the co-axiality tester; and then apply the test force to 4% of the maximum test force. Note that the maximum force used in the inspection shall not cause plastic deformation of the inspection specimen; and measure the elastic deformation of the opposite sides of the specimen, which shall be measured for three times each in the direction perpendicular to each other. The co-axiality is calculated according to Formula (1). The results of each verification shall meet the requirements of Table 2.
Where:
e ?€? Co-axiality between the center line of the upper and lower chucks in the afterburner system and the forcing axis of the testing machine, in %;
?????????????????? - In the same measuring point, and in the same measurement, the arithmetic mean of the deformation on both sides of the inspection specimen, in mm;
??Lmax - In the same measuring point, and in the same measurement, the deformation value of the side with the larger deformation of the inspection specimen, in mm. 6.2.3.2 For testing machines with a test force no greater than 30kN, use a heavy hammer and a matching centering disc for inspection. The center of the centering disc is engraved with a circle of ??2mm. During inspection, first hang the cone-shaped heavy hammer at the center of the upper fixture; and fix the centering disc at the center of the lower fixture. Move the movable fixture so that the test space is no less than 500mm; adjust the length of the suspension wire; and make the hammer tip as close as possible to the surface of the centering disc; and check whether the hammer tip falls within the specified diameter circle.
6.2.4 Zero drift
After the testing machine is preheated, select the minimum measuring range gear of the testing machine; adjust the zero point; observe the change of the zero-point indication of the testing machine within 15 min; and calculate the zero drift z according to Formula (2): Where:
z ?€? zero drift of force measuring system, in %;
F0d ?€? variation of indication value of zero point of the force measuring system, in N; FL ?€? lower limit of force measuring range, in N.
Its results shall meet the requirements of Table 3.
NOTE:
The lower limit of the measurement range of the testing machine for gear (including automatic gear) is 20% of the measurement range of each gear;
The lower limit of the measurement range of the un-geared testing machine is determined according to the instruction manual. If the instruction manual does not specify or the regulations are not standardized, it shall be determined by the multiple of the resolution:
Level-0.5 testing machine: 400??r;
Level-1 testing machine: 200??r;
Level-2 testing machine: 100??r.
6.2.5 Relative resolution
The relative resolution ?? of the force indicating device shall be calculated by Formula (3): Where:
?? ?€? relative resolution of force indicating device of testing machine, in %: r ?€? resolution of force indicating device, in N;
FL ?€? lower limit of force measuring range, in N.
The results shall meet the requirements of Table 1.
6.2.6 Allowable errors of force values
6.2.6.1 The standard force gauge shall stand for sufficient time to reach a stable temperature. 6.2.6.2 The testing machine shall apply the maximum test force at least three times as pre- compression or pre-tension.
6.2.6.3 Selection of verification points.
a) For the testing machine with gears: the verification points of each gear shall be no less than five; and they are generally evenly distributed according to 20%, 40%, 60%, 80% and 100% of each gear.
F ?€? when increasing the force, the real force value indicated by the standard dynamometer, in N.
The results shall meet the requirements of Table 1.
6.2.6.6 The relative error of forward and backward of indication value
For the testing machine with gears: on the maximum and minimum ranges of the testing machine, perform one force increment and decrement to verify the relative error of forward and backward of indication value.
For the testing machine without gears: within the range of 10%~100% of the measurement range and the range from the lower measurement limit to 10 times the lower measurement limit, three points are evenly selected (the coincident points are not repeatedly verified) to perform one force increment and decrement to verify the relative error of forward and backward of indication value, which shall be calculated according to Formulas (9) or (10): (a) When reading on the dynamometer based on the indicating device of the testing machine: Where:
u ?€? relative error of forward and backward of indication value of the force measuring system, in %:
F ?€? when increasing the force, the real force value indicated by the standard dynamometer, in N;
F?€? ?€? when decreasing the force, the real force value indicated by the standard dynamometer, in N;
??????? - For the same force point, the arithmetic mean of three measurements of standard dynamometer, in N.
(b) When reading on the indicating device of the testing machine based on the standard dynamometer:
Where:
u ?€? relative error of forward and backward of indication value of force measuring system, in %;
Fi?€? ?€? when decreasing force, the force indicated by the force indicating device of the testing machine under test, in N;
Fi ?€? when increasing force, the force indicated by the force indicating device of the testing machine under test, in N;
F ?€? when increasing the force, the real force value indicated by the standard dynamometer, in N.
The results shall meet the requirements of Table 1.
6.2.7 Error of indication value of displacement
Select two points of 1% and 10% of the maximum displacement at any position within the displacement measurement range of the testing machine for verification by a dial indicator or a height gauge. The verification results shall meet the requirements of Table 4. The relative error of indication value of displacement shall be calculated according to Formula (11):
Where:
qD ?€? relative error of indication value of displacement measuring system, in %; D?€? ?€? indication value of the displacement indicating device of the testing machine under test, in mm;
D ?€? indication value of the displacement standard, in mm.
6.2.8 The verification of the extensometer shall be performed according to JJG 762. 6.2.9 Noise
6.2.9.1 Before measuring the noise of the testing machine, the background (environmental) noise shall be measured firstly, and its value shall be at least 10dB (A) lower than the noise sound level of the testing machine. If the difference is less than 3dB (A), the measurement result is invalid. If the difference is (3~10) dB (A), the corresponding correction value shall be selected according to Table 7 and corrected according to Formula (12).
6.2.9.2 During verification, start the testing machine, apply a force of more than 80% of the maximum test force of the testing machine, and then place the microphone of the sound level meter horizontally facing the sound source, 1.0m away from the testing machine and 1.5m above the ground. The measurement is carried out on the test machine, and the measurement around the test machine should not be less than 6 points. The maximum value measured in each measurement point is used as the verification result of the test machine noise, which should

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