《ISO-4666-3-1982.pdf》由会员分享，可在线阅读，更多相关《ISO-4666-3-1982.pdf（9页珍藏版）》请在三一文库上搜索。
1、International Standard 4666/3 0 - depth 130 mm; - height 230 mm. The bottom of the chamber should be situated 25 IL 2 mm above the balance beam. A thermocouple of the same type as that used in the lower plate should be used for measurement of the temperature in the chamber. The thermocouple should b
2、e positioned at a distance of 6 to 9 mm towards the right hand side behind the rear edge of the plate and at a height midway between the plates. A length of at least 100 mm of the thermocouple wire should be within the chamber. The air circulation within the chamber is provided by a radial fan of 75
3、 mm diameter, operating at a rotational frequency of 25 to 28 Hz. The air intake should have a diameter of 60 mm. The air outlet should measure 40 mm x 45 mm. The grid shelf for supporting test pieces during conditioning should be fitted IO+ 2 mm above the bottom of the chamber. A diagram of the hea
4、ting chamber is shown in figure 2. 6.2 Measuring gauge The gauge for measuring the height and diameter of test pieces shall conform to the requirements of IS0 4646. A dial gauge having a circular foot probe of diameter 10 mm and exerting a pressure of 22 f 5 kPa is suitable. 6.3 Timer A stopwatch or
5、 other similar device shall be used. 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 02:16:45 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 4666
6、/3-1962 IE) 7 Procedure 7.1 Preparation of flexometer Locate the machine on a firm foundation. Adjust the levelling screws in the base to bring the machine into a level position in all directions at a point just to the rear of the fulcrum of the loading lever. With the loading lever locked in place
7、with the pin, place a level on the lever bar and verify the level setting. Adjust the eccentric to give a stroke or a double amplitude of 4,45 f 0,03 mm. This is best accomplished by means of a dial micrometer resting on either the cross bar of the upper anvil or by means of adapters attached to the
8、 loading arm of the eccentric. NOTE - The 4,45 mm stroke is selected as the standard for calibration purposes. When strokes other than 4,45 mm are to be used, the displacement of the lower anvil should be maintained within the tolerance specified for its height above the loading lever. The tolerance
9、 for all stroke settings shall be 5 0,03 mm. Raise the top anvil as far as the eccentric will permit by its rota- tion. Place a calibrating block of height 25,0 + 0,Ol mm on the lower anvil. NOTE - A suitable block may be made from brass having a diameter of 17,8 mm. The end to be placed on the lowe
10、r-anvil should be counterbored for clearance of the thermocouple disc. Raise the anvil by means of the micrometer until the bottom side of the metal cup holding the thermocouple is 67 Z!I 3 mm above thk top of the loading lever. The loading lever shall be in the locked position. Adjust the cross bar
11、 of the upper anvil, maintaining a parallel setting with the lower anvil and a firm contact with the calibrating block. The micrometer should now be set at zero. This may require disengagement of rhe gear train nearest the vernier scale of the micrometer. Remove the calibrating block and recheck the
12、 stroke or double amplitude for 4,45 mm setting. Set the pointer on the mark at the end of the lever bar. This establishes the level position. Remove the locking pin from the loading lever and gently oscillate the lever system to determine the point of rest. If the bar does not come to rest in appro
13、ximately the level position, slowly return it to its level position and release. If movement from the level position is observed, add or remove a weight to or from the required inertia weight to obtain a balance. 7.2 General test operation Check the machine for proper adjusment (see 7.1) and the re-
14、 quired test conditions (see clause 8). Place the necessary weights on the rear hanger to give the desired load. If a stroke otherthan 4,45 mm is desired, a new zero setting will be required on the micrometer after adjusting the eccentric to the new stroke. Proceed as outlined in 7.1 to obtain the z
15、ero setting. For elevated temperatures requiring the use of the heating chamber, allow a minimum of 2 h for preheating of the ap- paratus and the attainment of equilibrium prior to the start of test. Maintain the lower anvil at the zero setting, that is, 67 mm above the loading lever during the cond
16、itioning period. Measure and record the height of the test piece. Then measure its hardness in accordance with IS0 48. When the heating chamber is to be used, place the test piece in the chamber on the platform. Condition for a minimum of 30 min before the start of test. Before starting the test, th
17、e lower platen temperature and the ambient test temperature shall be equal. With the upper anvil or cross bar in its highest position, lower the bottom anvil and quickly position the test piece thereon, inverting its position from that used during the warm-up period. Raise the lower anvil by means o
18、f the micrometer until a firm contact is established with the upper anvil or hammer. Remove the locking pin and apply the load. Then advance the micrometer until the beam is again restored to its original level position as determined by the indicator. If the test piece had an original height of exac
19、tly 25,0 mm, then the micrometer reading may be used without correction for the compression height. When the original height of the test piece is less than 25,0 mm, then the difference shall be subtracted from the micrometer reading. For a test piece of height greater than 25,0 mm, the difference sh
20、all be added to the micrometer reading. For a smooth start, restore the pin to the locked position of the loading lever, and back off the micrometer three to four turns. Then loosen the pin, start the machine, and remove the pin completely. Immediately restore the beam to the level position by means
21、 of the micrometer and record the reading. Subject this reading to the same corrections as used for the static measurements. CAUTION - If the initial running deflection is less than one half of the impressed stroke or does not exceed this value within 1 or 2 min of the start, an unreliable and misle
22、ading temperature rise will be obtained. The loading lever must be maintained in a level position throughout the test. NOTE - The thermocouple in the lower anvil will stabilize at a temperature approximately 6 C lower in an ambient chamber temperature of 100 “C. This is the base temperature above wh
23、ich the temperature rise is measured. Any momentary drop in the base temperature at the start of the test should be disregarded. If a recorder is not used to obtain a continuous temperature rise curve, obtain a series of measurements using a suitable poten- tiometer. Plot the readings and draw the t
24、emperature rise curve. 7.2.1 Determination of temperature rise and of compression set To determine the temperature rise and the compression set, continue the test for the recommended test duration of 25 min, provided that no premature failure occurs in the test piece. Longer test durations may be re
25、quired if steady state conditions Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 02:16:45 MDTNo reproduction or networking permitted without license from IHS -,-,- are always to
26、 be attained, At the end of the test, remove the test piece from the apparatus and after storage for 1 h for cool- ing to standard laboratory temperature, measure the height h,. 7.2.2 Determination of fatigue resistance To determine the fatigue life, continue the test until breakdown occurs, Incipie
27、nt breakdown is revealed by an irregularity in the temperature curve (sudden temperature rise), by a marked in- crease in creep and by the onset of internal porosity. If no breakdown occurs, more severe testing conditions should be selected (see clause 81, The same test conditions shall be maintaine
28、d throughout a series of tests intended for comparison of a group of com- pounds. 9 Evaluation of test data 9.1 Temperature rise If the temperature in the bottom area of the test piece is 0, at the beginning of the test and 0% after 25 min of testing, then the temperature rise, Ad, expressed in degr
29、ees Celsius, is given by the formula 7.2.3 Determination of creep To determine creep, measure the test piece height 6 s after the stat-t of the cyclic loading and then after a specified test dura- tion. 8 Test conditions The conditions specified in the following table are normally employed in tests
30、with this compression flexometer. 1) A pre-stress of 1,O MPa is equivalent to a weight on the balance beam of 11 kg; a pre-stress of 2,0 MPa is equivalent to a weight of 22kg. Tests with the heating chamber removed are referred to as “room temperature” tests, or tests at standard laboratory temperat
31、ure. These may be selected for special test purposes if desired. The standard laboratory temperature used shall be specified in the test report. For the measurement of temperature rise a chamber tem- perature of either 55 OC or 100 OC may be selected with a stroke of 4,45 mm or 5,71 mm. Any of these
32、 choices of temperature and stroke may be used with either the I,0 or 2,0 MPa pre-stress on the test piece. These choices ordinarily give a temperature rise that is essentially at equilibrium after the normal test duration of 25 min. However, test times longer than 25 min may be selected, if desired
33、, for special test pur- poses. For measurement of the fatigue properties of rubber, more severe test conditions are needed, Specifically, strokes of 5,71 mm and 6,35 mm are recommended with the higher pre- stress or force on the balance beam. Selection of the more severe conditions avoids excessive
34、test durations for each test piece. In general, for medium hardness rubbers that have ordinary temperature rise characteristics, a pre-stress of 1,O MPa, a stroke of 5,71 mm and a chamber temperature of 55 OC or 100 OC is recommended. 9.2 Creep The creep, F, expressed as a percentage, is defined as
35、the dif- ference between the test piece height hs, determined 6 s after the start of the cyclic loading, and the test piece height h, determined after the test duration t, referred to the original height ho in the unloaded condition, i.e. h6 - h, F, = - x loo h0 I . I (2) The test piece height shall
36、 be measured as previously described. The balance beam shall be set to its zero position after not more than 6 s of running time. For the original height ho, the nominal value ho = 25 mm shall be used, since the dif- ferences must be within the tolerance range of f 0,2 mm. NOTE - The expression in e
37、quation (2) must be distinguished from the usual definition of creep in other cases, where creep is expressed relative to the initial deformation : F I = hc - “1 ho - hi * * , (3) The definition given in equation (2) has the advantage that there is no need to recalculate with reference to the height
38、 h6 in the loaded condi- tion. The quantity (he - h,)lho can also be easily read on the micrometer or recorded by an automatic compensator, since the original height ho is considered to be constant (within the tolerance limits rt: 0,2 mm). 9.3 Compression set The compression set, S, is given by the
39、difference between the original height ho and the final height h, after 1 h of cooling in an unloaded condition, referred to the original height ho, and is expressed as a percentage, all measurements being made at standard laboratory temperature, i.e. s= hO - he -x loo . . . h0 (4) 9.4 Fatigue life
40、The fatigue life is expressed as the number of cycles, IV, to breakdown or failure of the test piece. Breakdown or the failure criterion must be clearly defined and the definition cited. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Tec
41、hnical Standards 1/9972545001 Not for Resale, 04/25/2007 02:16:45 MDTNo reproduction or networking permitted without license from IHS -,-,- SO 4666/3-1982 (E) 10 Quality control check of flexometer operation It has been found that the use of a standard rubber formulation, prepared and vulcanized as
42、outlined below, allows for a rapid check of the operating condition of the compression flex- ometer. Standard formulation Material Parts (m/m) SBR 1500 100 Zinc oxide 5 Carbon black (N 330) 45 Stearic acid 1 Tetramethylthiuram disulphide 3 This compound should be vulcanized at 150 OC for 50 + 1 min.
43、 Test pieces cut from vulcanized block should give a temperature rise of 27 f 1 OC when tested using a stroke of 4,45 mm, a pre-stress of I,0 MPa and a chamber temperature of loo * I OC. 11 Test report The test report shall include the following particulars : al a reference to this International Sta
44、ndard; bi- sample details : 1) full description of the sample and its origin, 2) compound details and vulcanizing conditions, if known; 1) method of preparation, for example whether moulded or cut or taken from finished products, 2) original height and, in casa of deviations from stan- dard dimensio
45、ns, the diameter, 3) hardness; d) test conditions : 1) pre-stress, in megapascals, 21 stroke, in millimetres, 3) heating chamber temperature, in degrees Celsius; e) test results : I) for the measurement of temperature rise : the test duration, the individual values and the mean value, 2) for the mea
46、surement of creep : the test duration, the individual values and the mean value, as a per- centage, 3) for the measurement of compression set : the test duration, the individual values and the mean value, as a percentage, 4) for the measurement of fatigue resistance : the number of test pieces used,
47、 the criterion of fatigue failure, and the number of cycles to this selected failure point, expressed as individual values and the mean value; fJ any departures from the procedures specified in this International Standard; c) test piece details : gi the date of the test. 5 Copyright International Or
48、ganization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 02:16:45 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 4666/3-1662 (El , d -I /8 1 Upper plate 6 Balance beam 2 Test piece 7
49、 Additional weights 3 Lower plate 8 Weights 4 Micrometer screw 9 Screw 5 Pointer 10 Test piece support Figure 1 - Compression flexometer - General arrangement 6 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 02:16:45 MDTNo reproduction or networking permitted without license from IHS -,