1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 131-7:1998 ICS 77.040.
2、10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Notched bar tests Part 7: Specification for verification of the test machine used for precision determination of Charpy V-notch impact energies for metalsThis British Standard, having been prepared under the direction of the E
3、ngineering Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 December 1998 BSI 1998 First published May 1990 Second edition December 1998 The following BSI references relate to the work on this standard: Committee reference ISE/NFE/4/4 Draft f
4、or comment 97/700424 DC ISBN 0 580 28214 7 BS 131-7:1998 Amendments issued since publication Amd. No. Date Text affected Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee ISE/NFE/4, Mechanical testing of metals, to Subcommi
5、ttee ISE/NFE/4/4, Toughness testing, upon which the following bodies were represented: AEA Technology BEAMA Ltd. Electricity Association GAMBICA (BEAMA Limited) Institute of Materials Lloyds Register of Shipping Ministry of Defence National Physical Laboratory Railtrack Society of British Aerospace
6、Companies Limited UK Steel Association United Kingdom Accreditation Service Welding Institute Coopted membersBS 131-7:1998 BSI 1998 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Normative references 1 3 Definitions 1 4 Symbols 1 5 Principle 6 6 Verification of det
7、ails of test machine 6 7 Overall verification 13 8 Certificate of calibration 13 Bibliography 14 Figure 1 Types of hammer 2 Figure 2 Relationship of parameters used in calibration of machine 3 Figure 3 Test piece anvils 4 Figure 4 Configuration of anvil face 5 Figure 5 Disposition of reference surfa
8、ces 7 Figure 6 Configuration of test piece supports and anvils 8 Figure 7 Form and dimensions of striking edge 9 Figure 8 Striking edge with gauge bar in position 10ii BSI 1998 BS 131-7:1998 Foreword This part of BS 131 has been prepared by Subcommittee ISE/NFE/4/4. It supersedes BS 131-7:1990 which
9、 is withdrawn. It is intended that this part of this British Standard should be used in conjunction with BS 131-6, Notched bar tests Part 6: Method for precision determination of Charpy V-notch impact energies for metals. BS 131-6 and BS 131-7 are designed to satisfy the demand from sectors of Briti
10、sh industry for a more stringent standard of Charpy testing appropriate to the needs of specific applications where a more precise measure of Charpy impact energy is required. This part imposes strict control on machine parameters in order to meet the requirements of BS 131-6. The requirements of qu
11、ality control testing will continue to be met by BS EN 10045-1 and BS EN 10045-2, or BS 131-1, BS 131-4 and BS 131-5 unless BS 131-6 and BS 131-7 are specified in the product standard. A machine that has been calibrated to BS 131-7 may be used for testing in accordance with BS EN 10045-1. However, a
12、 machine calibrated to BS EN 10045-2 may not be used for testing in accordance with BS 131-6. Caution should be exercised when comparing results obtained on machines calibrated to different parts of this standard or with BS EN 10045. A British Standard does not purport to include all the necessary p
13、rovisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 1
14、4, an inside back cover and a back cover. BSI 1998 1 BS 131-7:1998 1 Scope This part of BS 131 specifies the way in which the test machine used to carry out precision Charpy V-notch impact tests is verified. 2 Normative references The following normative document contains provisions which, through r
15、eference in this text, constitute provisions of this part of this British Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the publication referred to applies. BS 131-6, Notched bar tests
16、Part 6: Method for precision determination of Charpy V-notch impact energies for metals. 3 Definitions For the purposes of this part of BS 131 the following definitions apply. 3.1 compensated machine machine in which correction for the loss in energy of the pendulum due to windage and friction has b
17、een made such that on a free half-cycle of swing of the pendulum from the release position the indicated absorbed energy is zero 3.2 non-compensated machine machine in which no correction for loss of energy due to windage and friction has been made NOTE With a machine of this type the indicated abso
18、rbed energy on a free half-cycle of swing of the pendulum will have a small positive value. 3.3 centre of strike that point on the striking edge of the pendulum at which, in the free hanging position of the pendulum, the vertical plane of the striking edge meets the upper horizontal plane of a test
19、piece of half standard height or equivalent gauge bar resting on the test piece supports 3.4 centre of percussion that point in a body at which, on striking a blow, the percussive action is the same as if the whole mass of the body were concentrated at that point. When the pendulum delivers a blow a
20、long a horizontal line passing through the centre of percussion there is no resulting reaction at the axis of rotation 3.5 initial potential energy energy theoretically available when the pendulum is located in the release position 3.6 reference specimen test piece of known impact value which can be
21、 used as a reference sample for testing the conformity of a machine to the required accuracy of performance 3.7 gauge bar unnotched bar made to the same nominal dimensions as a full size test piece 3.8 C-type pendulum pendulum in which any portion of the hammer or weighted mass at the lower end of t
22、he pendulum and distance greater than L s 15 mm from the spindle axis passes between the anvils of the impact test machine (see Figure 1) 3.9 U-type pendulum pendulum in which the part of the necessary weighted mass at the lower end is designed to pass below and on either side of the test piece anvi
23、ls of the impact test machine (see Figure 1) 4 Symbols For the purposes of this part of BS 131 the following symbols apply. A Initial potential energy of pendulum A v Calculated absorbed energy F 1 Force at centre of strike when the pendulum is horizontal (see Figure 2) H f Height of fall of centre
24、of strike of pendulum (see Figure 2) H r Height of rise of centre of strike of pendulum (see Figure 2) L a Distance between anvils (see Figures 3 and 4) L p Distance of centre of percussion of pendulum from axis of rotation (the radius of gyration) (see Figure 2) L s Length of pendulum from centre o
25、f strike of pendulum to axis of rotation (see Figure 2) M Moment of force of pendulum at its centre of strike r a Radius of curvature of anvils (see Figure 4) t Time for complete oscillation of pendulum V Impact velocity of pendulum at instant of strike u a Angle of taper of anvils (see Figure 3) u
26、f Angle of fall of pendulum (see Figure 2) u r Angle of rise of pendulum (see Figure 2)2 BSI 1998 BS 131-7:1998 C-type U-type Figure 1 Types of hammer BSI 1998 3 BS 131-7:1998 Figure 2 Relationship of parameters used in calibration of machine4 BSI 1998 BS 131-7:1998 Anvil Striking edge Test piece su
27、pports L a a q Figure 3 Test piece anvils BSI 1998 5 BS 131-7:1998 Figure 4 Configuration of anvil face6 BSI 1998 BS 131-7:1998 1) 1 J = 1 Nm. 5 Principle Individual details of the machine, i.e. all the dimensional features, are first verified. The overall performance of the machine is then verified
28、 by checking that it correctly records the energy values when breaking reference test pieces (see clause 7). 6 Verification of details of test machine 6.1 General The machine shall be calibrated in joules 1) and shall have one or more ranges. The nominal potential energy of these ranges shall be 150
29、 J, 300 J, 450 J and greater in increments of 150 J. The calibration of measuring apparatus shall be traceable to the National Physical Laboratory either directly or indirectly through a hierarchical chain such as that provided by the United Kingdom Accreditation Service (UKAS) in accordance with th
30、e accuracy demanded by the test. 6.2 Frame In order to minimize undue energy losses in the machine itself it shall be made of rigid construction, with all components securely fastened. The machine frame shall have been manufactured in a manner that allows the orientation of the spindle axis, test pi
31、ece supports and anvils to be checked by means of suitable gauging equipment. Reference surfaces shall have been incorporated as follows (see Figure 5): a) a horizontal surface, X, on the base adjacent to or immediately beneath the test piece supports; b) a first vertical surface, Y, perpendicular t
32、o the intended plane of swing of the pendulum and adjacent to or a continuation of the anvil location surfaces; c) a second vertical surface, Z, on a face of the machine frame parallel to the intended plane of swing such as to enable verification of the actual plane of swing. The three reference sur
33、faces shall be mutually perpendicular to one another to within 19 300. Some machines manufactured before the publication of this standard do not carry the Z reference surface. This shall be recorded in the calibration certificate (see clause 8) but if the machine satisfies all other requirements of
34、this standard it shall be deemed to conform to this part of BS 131. NOTE 1 For rigidity of the frame, it is recommended that machines manufactured after the publication of this standard should be such that the mass of that part of the frame below the horizontal plane of the supports is at least 12 t
35、imes the mass of the pendulum. NOTE 2 To distribute stresses through the frame as uniformly as possible, it is recommended that it include two similar upright pillars to carry the spindle axis, parallel to and equally spaced on either side of the intended plane of swing. NOTE 3 It is recommended tha
36、t the second vertical surface, Z, be on the face of the column adjacent to the pendulum. 6.3 Pendulum clearance The machine shall be constructed so as to minimize interference with the rise of the pendulum by the damaged test piece after initial impact. Endstops for locating specimens and protective
37、 shrouds shall be used only as prescribed in BS 131-6:1998. In a machine with a C-type pendulum, the width of the pendulum shall be no greater than 18 mm within a band of 30 mm height lying between L s 2 15 mm and L s +1 5m m . If protective shrouds are used with a machine having a U-type pendulum,
38、they shall be of minimum hardness 45 HRC. 6.4 Installation 6.4.1 The machine shall be rigidly bolted to a concrete floor or base not less than 150 mm thick and having a mass not less than 40 times that of the pendulum. The fastening bolts shall be tightly secured, preferably to a torque specified by
39、 the manufacturer. This torque value shall be checked at each verification of the machine. 6.4.2 The horizontal reference surface, X, shall be level in any two orthogonal directions to within 08 39 (1 : 1000) after installation. When shims have been used they shall be of ground hardened steel and sh
40、all support the machine over at least 75 % of the contact surface. 6.4.3 A check shall be made at installation and at each subsequent verification of the machine, to ensure that there are no vibrations passing through the machine foundation sufficient visibly to disturb the surface of water in a bow
41、l resting on the frame. 6.5 Supports and anvils 6.5.1 Orientation of supports The level of each test piece support shall be checked individually and shall be parallel to the true horizontal reference surface to within 08 39 (1 : 1000): a) in a direction parallel to the plane of swing; b) in a direct
42、ion perpendicular to the plane of swing of the pendulum. The faces supporting the test pieces shall be coplanar to within 0.05 mm. 6.5.2 Recess A relieving recess shall be provided in the support faces at the junction of the anvil and test piece support surfaces. The width of this recess parallel to
43、 the plane of swing shall not exceed 2 mm. 6.5.3 Orientation of the anvils The face of each test piece anvil shall be checked individually and shall be parallel to the vertical reference surface, Y, to within 08 39 (1 : 1000). The anvil faces shall be coplanar to within 0.05 mm. BSI 1998 7 BS 131-7:
44、1998 NOTE Where a Z reference surface is incorporated, the plane of swing of the pendulum is to be parallel to the Z surface to within 08 39, i.e. 1 : 1000. Figure 5 Disposition of reference surfaces8 BSI 1998 BS 131-7:1998 Figure 6 Configuration of test piece supports and anvils 6.5.4 Angle between
45、 test piece support and anvil faces The angle between the test piece support and anvil faces shall be 90 08 69 (see Figure 6). 6.5.5 Anvil tips 6.5.5.1 Radius of curvature The anvil tips shall have a radius of curvature, r a ,o f mm (see Figure 4). 1 0 +0.05 6.5.5.2 Verticality The anvil tips shall
46、be perpendicular to the horizontal reference surface, X, in planes parallel to the Y reference surface and the intended plane of swing to within 08 39 (1 : 1000) (see Figure 5). 6.5.6 Taper of anvil The angle of taper of each anvil, u a , shall be 798 18 (see Figure 4). 6.5.7 Distance between anvils
47、 The distance between the anvil tips, L a , shall be mm measured at the position shown in 40 0 +0.05 Figures 3 and 4. 6.5.8 Bearings and spindle At the bearing position, the transverse play of the spindle shall not exceed 0.25 mm, and the radial play shall not exceed 0.03 mm. This shall be checked c
48、oncurrently with the check for transverse stiffness in accordance with 6.6.5. The spindle axis shall be: a) parallel with respect to the horizontal reference surface, X, to within 08 39 (1 : 1000); and b) parallel with respect to the vertical reference surface, Y, to within 08 39 (1 : 1000). BSI 199
49、8 9 BS 131-7:1998 a) striker R 8 R 0.25 30 30 8 mm striker ASTM E23 4.0 0.1 4.5 2 mm striker R 2 to 2.5 b) detail of nose of striker All dimensions are in millimetres. Figure 7 Form and dimensions of striking edge 6.6 Pendulum assembly 6.6.1 Configuration of striking edge The striking edge of the pendulum shall be of either the 8 mm tip radius, shown in Figure 7, or the 2 mm tip radius of the following dimensions. The angle of the tip of the striker shall be 308 18, and the radius of curvature of the striking edge shall be m
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