1、BRITISH STANDARD BS 7442-4.2: 1994 Rubber or plastics covered rollers Part4: Requirements Section4.2 Classification by surface finishBS7442-4.2:1994 This British Standard, having been prepared under the directionof the Plastics and Rubber Standards Policy Committee, was published underthe authority
2、of the Standards Board and comes intoeffect on 15 December1994 BSI09-1999 The following BSI references relate to the work on this standard: Committee referencePRM/73 Draft for comment93/301803DC ISBN 0 580 23206 9 Committees responsible for this British Standard The preparation of this British Stand
3、ard was entrusted by the Plastics and Rubber Standards Policy Committee (PRM/-) to Technical Committee PRM/73, upon which the following bodies were represented: British Rubber Manufacturers Association Ltd. British Structural Bearings Manufacturers Association Building Employers Confederation Depart
4、ment of Transport Institution of Medical Laboratory Services Institution of Structural Engineers Malaysian Rubber Producers Research Association Ministry of Defence Royal Society of Chemistry Amendments issued since publication Amd. No. Date CommentsBS7442-4.2:1994 BSI 09-1999 i Contents Page Commit
5、tees responsible Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Definitions 1 4 Classification 1 5 Documentation 2 Annex A (informative) Relation between surface treatment and surface roughness 3 Table 1 Types of surface treatment 1 Table 2 Parameters for specified R a 2 Table 3 Parameter
6、s for specified R z 2 Table A.1 Values of R zas a function of surface treatment 3 List of references Inside back coverBS7442-4.2:1994 ii BSI 09-1999 Foreword This British Standard has been prepared under the direction of the Plastics and Rubber Standards Policy Committee. It is based upon ISO6123-2:
7、1988 but there are significant points of departure from the International Standard. In particular, no attempt is made to classify imperfections because, although the International Standard includes such a classification, it is based on a quantity of “imperfections” declared by their surface area, wi
8、thout any means of measuring the surface area of such imperfections and without any cognizance being taken of the depth of imperfection. Until these issues can be clarified, this standard restricts the classification of surface characteristics to surface finish only, as measured by either surface ro
9、ughness values or type of finish. The surface characteristics of the covering of any roller need to be suitable for the particular process for which the roller is to be used. In some cases it is critical that the surface of the roller, apart from being concentric and of a suitable hardness and resil
10、ience, is as smooth as possible. In other cases the surface roughness may be of very little consequence. Also, as covered rollers are used over such a wide range of industries, from food processing, oil extraction, paper production, and textile production and processes to printing and packaging, it
11、is not possible to specify the surface qualities of the rollers required in every case. Consequently a classification system is proposed which allows the user to select the surface finish most appropriate to the end-use to which the roller is to be put. A British Standard does not purport to include
12、 all the necessary provisions 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, pagesi a
13、ndii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS7442-4.2:1994 BSI 09-1999 1 1 Scope This Section of BS7442 provides a syste
14、m of classifying rubber covered or plastics covered rollers according to the surface finish, determined either by the type of surface treatment, or by the surface roughness. A test method for the determination of surface roughness is included. 2 References 2.1 Normative references This Section of BS
15、7442 incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cited applies: any subsequent amendme
16、nts to or revisions of the cited publication apply to this British Standard only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 2.2 Informative references This Section of BS7442 r
17、efers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Definitions For the purposes of this Section of BS7442 the defini
18、tions given in BS7442-0 and BS7442-1 apply. 4 Classification 4.1 Surface finish The surface finish of a roller cover is dictated by the intended use and is characterized either as a type of surface treatment (see4.2) or as the maximum value of surface roughness (see4.3). 4.2 Classification by surfac
19、e treatment 4.2.1 General Table 1 shows the principal methods of surface treatment, which are used to classify the roller surfaces. These are described in4.2.2.1. The type of surface finish, and the structure or texture which can be achieved, are dependent upon the hardness and composition of the ro
20、ller cover (seeAnnex A). Special treatments, not dealt with in4.2.2.1 are referred to in4.2.2.2. Table 1 Types of surface treatment 4.2.2 Description by surface treatment types 4.2.2.1 Types1 to5 The surface structures described for types1 to4 are produced by regular treatments and have a roughness
21、without preferential direction. a) Type1: polished finish. In soft rubbers, the surface is velvet-like; in hard rubber, ebonite or hard plastics, it is smooth. Grinding marks and scratches are not visible to the naked eye. Sporadic grinding blemishes are permissible. NOTENot all compounds permit thi
22、s finish. b) Type2: fine grinding finish. Slight grinding and feed marks are visible to the naked eye, but are not noticeable to the touch. c) Type3: standard grinding finish. Grinding marks and grinding feed are visible and just noticeable to the touch. d) Type4: turned finish. The surface is solel
23、y turned, with as little feed of the turning tool as practicable. Turning grooves are visible and noticeable to the touch. e) Type5: unground finish. The surface of the roller is without any treatment or dressing, for example a cloth-marked roller surface as it comes from the vulcanization process o
24、r a rough-cast plastics covered roller. 4.2.2.2 Type S: special treatment This applies to surface finishes other than those of types1 to5, for example a fine-cast plastics covered roller, or to a finish for specific applications with a special structure. 4.3 Classification by surface roughness 4.3.1
25、 General Surface roughness is quantitatively expressed in one of the following ways: a) as the arithmetical mean deviation of the profile R a(see BS1134-1), in micrometres; b) as the ten point height of irregularities R z(seeBS1134-1, in micrometres. Surface roughness is determined according to the
26、method outlined in4.3.2 to4.3.8. Type Surface treatment Typical appearance orfeel 1 2 3 4 5 Polishing Grinding, fine Grinding, standard Turning Unground finish Smooth to velvet Smooth Tactile fine grain Tactile ridges Process dependentBS7442-4.2:1994 2 BSI 09-1999 4.3.2 Apparatus 4.3.2.1 Profile met
27、er, conforming to BS1134-1 and equipped with a support for use on curved surfaces. The contact stylus shall be calibrated at the indicated measurement values (for example by use of a reference surface of known roughness). The contact stylus shall operate dynamically at an angle of90 to the tangent o
28、f the plane of the roller surface. It shall have a radius of stylus tip of54mmax. It shall exert a static measuring force at mean level of stylus of4mNmax. 4.3.3 Sampling length, evaluation length and cut-off The sampling length l and the evaluation length l nshall be as specified in BS1134-1. NOTEF
29、or rubber covered or plastics covered rollers, common values of cut-off B , sampling length (l) and the evaluation length (l n ) encountered in practice are illustrated in Table 2 and Table 3. Table 2 Parameters for specified R a Table 3 Parameters for specified R z 4.3.4 Test conditions The test sh
30、all be carried out, wherever practicable, at a standard temperature(23 C 2 C or27 C 2 C) in accordance with BS903-A35. The covered roller shall be brought to the test temperature prior to testing to ensure temperature equilibrium and the test temperature recorded. 4.3.5 Measurement For rollers havin
31、g a cover up to and including2.5m in length, the roughness shall be measured in five areas: a) three areas, each120 apart, around the circumference in the middle of the roller; b) one area at each end of the roller, at a distance of10% of the cover length from the end of the roller covering. For rol
32、lers having a cover over2.5m in length, the roughness shall be measured in nine areas: 1) three areas, each120 apart, around the circumference in the middle of the roller; 2) three areas at each end, each120 apart, around the circumference, and each at a distance of10% of the cover length from the e
33、nd. The sampling length of each measurement shall be the evaluation length plus the pre-measuring and the post-measuring lengths. 4.3.6 Test procedure Before measurements are made, clean the cover surface carefully to remove dust and other contaminants which have collected during storage. Ensure tha
34、t the cleaning does not damage the surface. NOTEWiping the surface with propan-2-ol (isopropyl alcohol) has been found to be suitable. Firmly place the roller to be tested with its longitudinal axis horizontal and with the area in which the surface roughness is to be measured uppermost. Place the me
35、asuring equipment on the roller and adjust the pick-up so that the correct static measuring force at the mean level of the stylus is exerted on the surface. Make one measurement in each measuring area with the stylus traverse line parallel to the axis of the roller. 4.3.7 Expression of results For e
36、ach measuring area specified in4.3.5, the arithmetical mean deviation of the profile, R a , or the ten point height of irregularities, R z , respectively, shall be recorded. The roughness of the roller cover surface shall be reported as the average of all readings taken in accordance with4.3.5. 4.3.
37、8 Repeatability and reproducibility The difference between two single test results obtained on identical test material under the repeatability conditions specified for a particular determination will exceed20% on average not more than once in20 cases in the normal and correct operation of the method
38、. The difference between two single and independent test results obtained by two operators working under the specified reproducibility condition in different laboratories on identical test material will exceed50% on average not more than once in20cases in the normal and correct operation of the meth
39、od. 5 Documentation Each delivery of roller covers or covered rollers shall be accompanied by documentation which identifies the delivery in terms of the following information. a) the name and/or distinctive mark of the manufacturer and the batch number; b) the number and date of this British Standa
40、rd, i.e.BS7442-4.2:1994; c) the classification, i.e.the type of surface finish or surface roughness. R a m B mm l mm l n mm 0.1 up to2 2 up to10 0.8 2.5 0.8 2.5 4.0 2.5 R z m B mm l mm l n mm 0.5 up to10 10 up to50 0.8 2.5 0.8 2.5 4.0 12.5BS7442-4.2:1994 BSI 09-1999 3 Annex A (informative) Relation
41、between surface treatment and surface roughness Surface finish may be classified either by treatment (see4.2) or by roughness (see4.3). The approximate relation to be expected between the type of treatment and the surface roughness obtained is given in Table A.1. It should be noted that the same tre
42、atment generates different roughness values on covers not only of different hardnesses but to some extent also of different polymers or compounds and is also dependent upon such factors as machine settings, and speeds (rotational, surface and traverse rates). NOTETable A.1 is restricted to R zvalues
43、 as it is these values, along with maximum profile height (R y ) (see BS1134), shear strength and resilience which are likely to have a significant influence on the performance of the roller in use. Table A.1 Values of R zas a function of surface treatment Cover hardness Roughness value R zof surfac
44、e finish (in 4m max.) IRHD or Shore A Pusey and Jones 1 Polishing 2 Grinding, fine 3 Grinding, standard 4 Turning 5 Unground, finish120 120 to 10 9 to 0 8 7 6 12 10 8 12 10 8 Process dependent4 blankBS7442-4.2:1994 BSI 09-1999 List of references (see clause2) Normative references BSI publications BR
45、ITISH STANDARDS INSTITUTION, London BS903, Physical testing of rubber. BS903-A35:1985, Temperatures, humidities and times for conditioning and testing of test pieces. BS1134, Assessment of surface texture. BS1134-1:1988, Methods and instrumentation. BS7442, Rubber or plastics covered rollers. BS7442
46、-0:1991, Introduction. BS7442-1:1991, Glossary of terms. Informative references ISO publications INTERNATIONAL ORGANIZATION FOR STANDARDIZATION (ISO) Geneva. (All publications are available from BSI Customer Services, Sales Department) ISO6123-2:1988, Rubber or plastics covered rollers Specification
47、s Part2: Surface characteristics. BS 7442-4.2: 1994 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is incorporat
48、ed by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStandards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone find
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