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1、International Standard 4647 0 + b) the complete identification of the cord; c) details of the rubber compound, cure time and temperature; d) the method of preparing test pieces; e1 the conditioning temperature and relative humidity; f) the test temperature; g) any non-standardized procedure(s); h) t
2、he number of test pieces tested; j) all individual test results and the arithmetic mean of the results; k) the type of grip used; m) the type of failure; nl the date of test. -,-,- Is0 4847-1982 (E) Annex Preparyation of silicone-rubber-faced bars A.1 Silicone compound preparation A.l,l The compound
3、 used shall be a self-bonding grade of silicone rubber of hardness about 60 IRHD. A.1.2 Depending on the mould plate size available, press out between sheets of polyester a 50 to 60 g piece of the com- pound, using two flat mould plates to obtain as even a thickness (1,5 mm) as-possible. The pressin
4、g is best done in a hydraulic press at very low pressure (less than 175 kPa). A hand-pump press is preferable. The platens may be heated to 50 to 70 OC, if preferred. A.1.3 After pressing for 2 to 3 min, examine the silicone rub- ber to see if the required thickness has been reached. It may not be p
5、ossible to attain 1,5 mm, but up to 2 mm is per- missible. A.1.4 Remove the sheet of silicone rubber and store it on a flat cool surface, still protected by the polyester film. A.2 Bar preparation A.2.1 Remove as much old silicone rubber as possible by scraping, mechanical wire-brushing of the bars,
6、 or similar means. A,2.2 Degrease the bars in a vapour degreasing bath, using trichloroethylene or perchloroethylene, for 30 to 60 min. A.2.3 Abrade the bars on the bonding surfaces only, using fine emery cloth. Light shot or vapour blasting may be used, but it is advisable to protect the non-bondin
7、g surfaces to pre- vent unnecessary roughening. A.2;4 Finally clean the bars by wiping liberally with a clean cloth soaked in a petroleum solvent, the solvent being allowed to evaporate. Apply the silicone strip as soon as possible after cleaning. A.3 Bonding procedure A-3.1 Cut strips from the poly
8、ester film-protected silicone rubber to fit the bonding areas on the bars. If the silicone rub- ber is unavoidably thick, the width of the strips (normally about 10 mm) may be reduced by 1 to 2 mm to prevent excessive spew. A.3.2 Peel the polyester film from one face of the strip, place the exposed
9、face on the freshly cleaned bonding area and, manually, lightly press into contact. Avoid contact with the exposed silicone surface and the prepared bar surface to prevent contamination and hence poor bonding. A.3.3 Prepare two bars at a time. These should be used as a pair, and preferably marked fo
10、r easy identification. A.3.4 Place the bars in a suitable mould, side by side, with the siliconed faces uppermost. The top layers of polyester film may now be removed if preferred, but to facilitate easy demoulding a piece of polyester film, sufficient to cover the mould cavity, should be inserted.
11、Alternatively, the mould lid should be sprayed with a PTFE aerosol mould lubricant. A-3.5 With the lid located by the matching holes and pegs of the bars, place the mould in a press while the platens are warm- ing up, and use a low pressure to spread the silicone. When the full curing temperature of
12、 160 OC is reached, apply the highest possible safe pressure and vulcanize for 15 min. A.3.6 Cool the bars, preferably in the mould in the press still under pressure. If this is not possible, allow the complete mould to cool out of the press, as at this stage the silicone is still weak and prone to
13、damage when hot. A.3.7 When cool, carefully remove the faced bars from the mould. This may be facilitated by removing one of the screwed- in mould end stops, allowing a thin lever to be inserted under the bars. A.3.8 Excess silicone spew, etc., may then be trimmed off, or this may be deferred until
14、after the oven cure. A.3.9 When all the bars to be re-faced have been press- cured, store them for 18 to 24 h at 200 OC. Remove excess spew, etc., if this was not carried out at the previous stage. NOTES 1 When in use, the silicone rubber may protrude beyond the edge of the bar. If a trial pull-thro
15、ugh test piece is moulded, the amount of ex- cess silicone may be measured by examining the test piece cross- section, which will be of H-section if the silicone protrudes. The edge of the silicone should be trimmed back from the edge of each bar by slightly less than the depth of the indentation ca
16、used in the pull- through test piece. 2 With normal usage, a minimum of 500 test mouldings can be ex- pected before the bars need to be refaced. A- -,-,- IS0 4647-1982 (E) Rubber + - L Direction of applied force Figure 1 - Test piece Dimensions in millimetres Material HA. Steel Four slots 0,8 or 1,2
17、 wide t and 3,0 deep, remove burrs Figure 2 - Suitable mould for H-pull test NOTE - The mould as shown will produce 16 test pieces. It may be fabricated to produce a larger or smaller number but the dimensions that govern the size of the test pieces shall not be altered. IS0 4647-1982 (E) Dimensions
18、 in millimetres Plan Mould frame R x - R - x R x R x R - - X - - 2 S 2 S 2 P 2 P R P R P R X, IO 10 IO 10 IO IO X X Mould top plate m R5 R6 zz 72 Mould base plate Method A SectionA-A Method B R - Rubber cavity, width X and depth Y (see 5.1 and 6.1) S - Silicone-rubber-faced bar P - Plain spacer bar
19、C - Cord grooves, width 0,8 or 1,2 (see clause 5.1) Figure 3 - Methods of preparation of test pieces -,-,- IS0 4647-1982 EI Drill and tap to facilitate attaching to tester 7 a Lu - - Break all sharp edges and corners with slight radii Dimension mm A 1,6 B 12,5 c 25,0 D JO,0 E 7,o F 14.0 G 48 H 2,0 F
20、igure 4 - Test piece grip NOTE - The important dimension is indicated by an asterisk and shall not be altered. All other dimensions are included for guidance and may be altered if desired. 7 -,-,- IS0 4647-1982 (El Dimensions in millimetres -d-k - Figure 5 - Alternative test piece grip NOTE - The lower part of the grip is spring loaded with a spring tension of between 5 and 15 N to minimize deformation of the rubber. 8