This standard specifies the measurement method, measurement device, sampling, specimen preparation and calculation formula for the transverse bending of hot bimetallic strips and strips. JB/T 7131-2002 Hot bimetallic transverse bending test method JB/T7131-2002 Standard download decompression password: www.bzxz.net

ICS29.120.20
Machinery Industry Standard of the People's Republic of China
JB/T7131—2002
Replaces JB/T7131-1993
Hot bimetal transverse bending test method
Standard test method for cross curvature of thermostat metals (ASTM B478-85 [Reapproved 1997], MOD 2002-12-27 issued
2003-04-01 implementation
The State Economic and Trade Commission of the People's Republic of China issued Foreword,
1 Scope..
2 Terms and definitions
3 Overview of measurement methods
4 Significance and application.
5 Measuring device.
Specimen preparation
8 Test steps.
9 Calculation formula.
10 Test report,
JB/T 7131-2002
Appendix A (Informative Appendix) Comparison of the number of this standard and the number of ASTMB478-85 (confirmed in 1997) Appendix B (Informative Appendix) Accuracy and deviation. Figure 1 Schematic diagram of transverse bending measurement method
Figure 2 Typical fixture for measuring transverse bending Table A.1 Comparison of the number of this standard and the number of ASTMB478-85 (confirmed in 1997) Table 4
JB/T7131-2002
This standard is modified to adopt the American Society for Testing and Materials standard ASTMB478-85 (1997 This standard replaces JBT7131--1993 "Hot Bimetal Transverse Bending Test Method". This standard is redrafted based on ASTMB478-85 (confirmed in 1997). The "keywords" have been deleted, and a comparison table of the chapter and article numbers of this standard and ASTMB478-85 (confirmed in 1997) is listed in Appendix A. Taking into account my country's national conditions, modifications were made when adopting the ASTM standard. The relevant technical differences have been compiled into the standard text, and the margins of the clauses they involve are marked with a vertical single line. Technical differences and reasons Because: It is coordinated with GB/T4461-1992 "Hot Bimetallic Strip", and the calculation formula of the transverse bending curvature radius is added; for the convenience of standard application, the test temperature is adjusted from 24℃±0.5℃ to 24℃±2℃. Compared with JB/T7131-1993, the main changes of this standard are as follows: the writing format conforms to GB/T1.1-2000 "Guidelines for Standardization Work Part 1: Structure and Writing Rules of Standards"; the test temperature is adjusted from 20℃ to 24℃ (1993 Edition 9.1, this edition 8.4): Appendix A and Appendix B of this standard are both informative appendices. This standard is proposed by the China Machinery Industry Federation. This standard is under the jurisdiction of the National Electrical Alloy Standardization Technical Committee. This standard is drafted by the Shanghai Electric Science Research Institute. The main drafter of this standard: Yu Jie.
This standard was first issued in 1993, and this is the first revision. Ⅲ
1 Scope
Thermostatmetal transverse bending test method
JB/T7131—2002
1.1 This standard specifies the measurement method, measuring device, sampling, specimen preparation and calculation formula of transverse bending of thermostatmetal sheets and strips.
This standard is applicable to the measurement of transverse bending of thermostatmetals and also to the precise measurement of transverse bending of other materials. 1.2 This standard does not cover all safety factors. Before using this standard, the user is responsible for establishing an appropriate safety system. 2 Terms and definitionsbZxz.net
The following terms and definitions apply to this standard. 2.1
Thermostatmetal
A composite material composed of two or more layers of metal or alloy components, usually made into sheets or strips. Due to the different thermal expansion properties of each component layer, the bending of the material changes with the change of temperature. 2.2
Transverse bend
erosseurvature
<Material> Deviation from the plane in the entire width direction, expressed as chord height, in mm. 3 Overview of measurement method
The measurement of transverse bend is shown in Figure 1: that is, the deviation of the entire width (L) of the hot bimetallic specimen from the plane (chord height C) is measured. Place the specimen on the pad of the special measuring device with the convex surface facing up, and use a depth micrometer to measure the distance from the highest point of the specimen to the plane of the pad. The transverse bend or the radius of curvature of the transverse bend of the specimen is calculated by the formula. Note: In the normal case, the highest point is at (or close to) the center of the specimen. Specimen
77777X7777777777777777777X77X777 Reference plane
Figure 1 Schematic diagram of transverse bending measurement method
4 Significance and application
This standard provides a method for determining the size and direction of transverse bending (inherent property of thermal bimetal) 5 Measuring device
5.1 Fixture - The typical fixture for measuring transverse bending is shown in Figure 2: It consists of a base, a reference plane, a bracket, a guide rail, a depth micrometer, a parallel pad and an electrical contact indicator. The upper end surface of the base is the reference plane, and above it is a movable guide rail. The rail is parallel to the reference plane. A movable bracket is assembled on the rail. 5.2 Depth micrometer - The minimum graduation value is not more than 0.0025mm. The end of the measuring rod should be made into a spherical surface and fixed on the movable bracket. It can move on the guide rail along the width direction of the specimen to find the highest point of the specimen. 1
JB/T7131—2002
Reference plane
Degrees and scale
Figure 2 Typical fixture for measuring transverse bending 5.3 Electrical contact indicator - High sensitivity, low current, used to determine the contact status of the depth micrometer measuring end, and sends an electrical signal when the depth micrometer measuring end contacts the sample or parallel pad. 5.4 Parallel pad - Rate steel that carries the sample to be tested, with a size of 6mmx10mmx150mm5.5 Within the moving range of the depth micrometer along the length of the parallel pad, the distance deviation from its measuring end to the parallel pad is not greater than 0.005mm. 6 Sampling
The sampling method is agreed upon by the manufacturer and the customer. 7 Sample preparation
The most important step in preparing the test sample is cutting the sample length. The sample should be straight in the longitudinal direction, and the sample length is approximately equal to the width of the strip. The minimum length of the sample is 20mm. It is advisable to use a sharp blade for shearing. Shearing should not cause serious burrs on the specimen, and the cutting of the specimen should not change its inherent transverse curvature. After cutting, the specimen should be placed for 10 minutes before measurement so that its shape is stable. 8 Test steps
8.1 Place the 6mm wide plane of the parallel pad on the reference plane and move it below the depth micrometer. Its length direction is consistent with the direction of movement of the bracket. Rotate the depth micrometer until the electrical contact indicator sends a signal, indicating that the measuring end is just in contact with the upper surface of the parallel pad. Record the depth micrometer reading at this time as the base point (B) 8.2 Reverse the depth micrometer and move the bracket away. Place the specimen in the center on the parallel pad, with the convex surface facing up, and the two sides of the specimen width in contact with the parallel pad. Be careful to prevent the specimen from tilting or poor contact with the parallel pad. Then move the bracket to the top of the specimen and find the highest point. Measure and record the depth micrometer reading at the highest point of the specimen in the same way as 8.1 (H). 8.3 Use a spherical outer diameter micrometer to measure the thickness of the sample (t). The minimum graduation value of the spherical outer diameter micrometer shall not exceed 0.0025mm. 8.4 All measurements shall be carried out at a temperature of 24℃±2℃, and the sample shall be placed at this temperature for 30 minutes before measurement. 9 Calculation formula
The calculation formula for transverse bending is as follows:
C=BH-
Wherein:
Transverse bending, in mm:
The reading of the depth micrometer at the base point of the parallel pad, in mm: The reading of the depth micrometer at the highest point of the sample, in m; Sample thickness, in mm.
JB/T7131—2002
Note: The transverse bending size of materials with the same radius of curvature changes with the change of the sample width. For example, the transverse bending dimension of a strip with a width of 76.2 mm is 2.3 mm, while the transverse bending dimension of a strip with the same radius of curvature and a width of 25.4 mm is only 0.3 mm. For strips with a low width-to-thickness ratio, they may also be affected by mechanical deformation caused by the mouth during the strip opening or shearing process. The transverse bending dimension takes a positive value (+10), when the active layer is convex (high 9.2 When the passive layer of the hot bimetallic strip is convex (the low expansion surface is convex), the column expansion surface is convex), the transverse bending dimension takes a negative value (-9.3 The calculation formula for the transverse bending curvature radius is as follows: R=
Wherein:
R—transverse bending curvature radius, in mm: C—transverse bending dimension, in mm
L-specimen width dimension, in mm.
Test report
The contents of the test report are as follows:
Material type and brand;
Specimen thickness;
Specimen width:
Measurement temperature:
Reading of the depth micrometer at the base point of the parallel pad; Reading of the depth micrometer at the highest point of the specimen; L2
Transverse bending dimension or transverse bending curvature radius (including positive and negative numbers) (2)
JB/T7131—2002
Appendix A
(Informative Appendix)
Comparison between the chapter and clause numbers of this standard and the chapter and clause numbers of ASTMB478-85 (confirmed in 1997) Table A.1 gives the comparison between the chapter and clause numbers of this standard and the chapter and clause numbers of ASTMB478-85 (confirmed in 1997). Comparison table of chapter and clause numbers of this standard and those of ASTM B478-85 (confirmed in 1997) Table A.1
Chapter and clause numbers of this standard
Chapter 3
Chapter 4
Chapter 7
Chapter 10
Appendix B
Appendix B
(Informative Appendix)
Precision and deviation
ASTM B478-85 (confirmed in 1997) Chapter and clause numbers 3.1
5.4 Notes
9.1 Notes
Chapter 11
The reliability of transverse bending measurement results mainly depends on the cutting method and measuring conditions of the specimen. The common causes of unstable measurement results are the uniformity of the specimen cutting process and the measuring temperature. People's Republic of China
Mechanical Industry Standard
Hot Bimetal Transverse Bending Test Method
JB/T7131—2002
Published and distributed by Machinery Industry Press
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2003 1st edition, 1st printing, April 2017
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