BS 7792-1995 Specification for industrial plate screens《工业用板材筛选规范》.pdf

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1、BRITISH STANDARD BS 7792:1995 ISO 10630: 1994 Specification for Industrial plate screensBS7792:1995 This British Standard, having been prepared under the directionof the Materials and Chemicals Sector Board (I/-), waspublished under the authorityof the Standards Boardand comes into effect on 15 Febr

2、uary 1995 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference LBI/37 Draft for comment 92/84784 DC ISBN 0 580 23719 2 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee LBI/37, S

3、ieves, screens and particle sizing, upon which the following bodies were represented: BLWA Ltd (The Association of the Laboratory Supply Industry) British Cement Association British Coal Corporation Coated Abrasives Manufacturers Association Guild of Metal Perforators Institution of Chemical Enginee

4、rs Institution of Mining and Metallurgy Ministry of Defence NABIM Society of Chemical Industry Society of Cosmetic Scientists Woven Wire Association The following bodies were also represented in the drafting of the standard, through a subcommittee: British Aggregate Construction Materials Industries

5、 Minerals Engineering Society Amendments issued since publication Amd. No. Date CommentsBS7792:1995 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Definitions 1 4 Symbols 2 5 Requirements 2 6 Test procedure 3 7 Irregula

6、rities caused by the perforating process 3 8 Surface characteristics 4 9 Perforated metal plate in coils 4 Figure 1 Examples of hole arrangements 5 Figure 2 Characteristics of a perforated plate 6 Figure 3 Measurement of amount out-of-square 6 Figure 4 Cross section of perforated metal plate 7 Figur

7、e 5 Measurement of wavy edge 7 Figure 6 Measurement of edge bow 8 Figure 7 Patterns of perforations caused by different tool arrangements 8 Table 1 Symbols used to describe perforated metal plate 2 Table 2 Tolerances on width and length 3 Table 3 Tolerances on squareness 3 Table 4 Tolerances on widt

8、h of margins 3 Table 5 Tolerances on flatness 4 Table 6 Maximum height of burrs 4 List of references Inside back coverBS7792:1995 ii BSI 10-1999 National foreword This British Standard has been prepared by Technical Committee LBI/37. It is identical with ISO10630:1994 Industrial plate screens Specif

9、ication and test methods, published by the International Organization for Standardization (ISO). ISO10630 has been prepared by Subcommittee7of Technical Committee ISO/TC24, with the active participation and approval of the United Kingdom. A British Standard does not purport to include all the necess

10、ary 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. Cross-references International Standard Corresponding British Standard ISO 2194:1991 BS 7579:1992 Spec

11、ification for designation and nominal sizes of openings for woven wire cloth, perforated plate and electroformed sheet for industrial screens (Identical) BS 6620 Industrial plate screens ISO 7805-1:1984 Part 1:1991 Guide for screens of thickness 3 mm and above (Identical) ISO 7805-2:1987 Part 2:1991

12、 Guide for screens of thickness below 3 mm (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This

13、 will be indicated in the amendment table on the inside front cover.BS7792:1995 BSI 10-1999 1 1 Scope This International Standard specifies technical requirements and test methods for perforated metal plate used for industrial screening purposes and supplied in flat or coiled form. It applies to per

14、forated plates of low carbon steel according to ISO7805-1 and ISO7805-2 with nominal sizes of holes from1mm for round holes and4mm for square holes up to125mm according to ISO2194, and with a maximum plate thickness of12,5mm. 2 Normative references The following standards contain provisions which, t

15、hrough reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of a

16、pplying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 2194:1991, Industrial screens Woven wire cloth, perforated plate and electroformed sheet Designation and nominal sizes of openings. ISO 7805-1:

17、1984, Industrial plate screens Part1:Thickness of 3 mm and above. ISO 7805-2:1987, Industrial plate screens Part2:Thickness below 3 mm. 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 plate flat rolled material for the manufacture of perforated met

18、al plate,3mm to12,5mm thick, the edges of which are allowed to deform freely during rolling, supplied in flat form and generally in rectangular shape, but also in any other shape according to a design sketch 1) 3.2 sheet flat rolled material for the manufacture of perforated metal plate, less than3m

19、m thick, the edges of which are allowed to deform freely during rolling, supplied in flat form and generally in rectangular shape, but also in any other shape according to a design sketch 1) 3.3 coil flat rolled sheet for the manufacture of perforated metal plate, the edges of which are allowed to d

20、eform freely during rolling and which immediately after the final rolling pass is wound into regular superimposed laps 3.4 perforated plate screening surface consisting of a plate with uniform holes in symmetrical arrangement. The holes may be square, slotted, circular or of other regular geometrica

21、l shape 3.5 plate thickness thickness of the plate before perforation 3.6 feed direction direction in which a plate or sheet was fed through the perforating press 3.7 punch side surface of a perforated plate which the punch entered 3.8 hole size diameter of a round hole or distance between opposite

22、sides of a square hole of a perforated metal plate 3.9 pitch distance between corresponding points of two adjacent holes in a perforated plate 3.10 bridge width; bar distance between the nearest edges of two adjacent holes in a perforated plate 3.11 margin distance between the outside edges of the o

23、utside rows of holes and the edges of a perforated plate 3.12 percentage open area ratio, expressed as a percentage, of the total area of the holes to the total area of the perforated part of the plate (excluding any non-perforated parts) 1) After perforation, plates and sheets are both designated a

24、s “perforated plate”, see3.4.BS7792:1995 2 BSI 10-1999 3.13 roller levelling cold mechanical operation on a perforated metal plate to promote flattening 4 Symbols SeeTable 1. 5 Requirements 5.1 Hole size and pitch (see Figure 1) The tolerances on the hole size and the pitch of both round and square

25、holes are specified in ISO7805-1 for perforated plate of thickness of3mm and above, and in ISO7805-2 for perforated plate of thickness below3mm. 5.2 Plate thickness (see Figure 2) The plate thickness shall be less than the nominal hole size and less than the bridge width (bar), unless otherwise agre

26、ed between the interested parties. NOTE 1The uniformity of the plate thickness before perforation depends on the tolerances applied at the rolling mill which supplies the unperforated material and conforms to the so-called “mill tolerances”. Specific tolerances, if required, shall be agreed before o

27、rdering. 5.3 Plate width and length (see Figure 2) The tolerances on plate width a 1and plate length b 1for plates cut on all edges are given in Table 2. NOTE 2Stock sizes of perforated plates are usually supplied without cutting after perforation and roller levelling. In these cases, because stretc

28、h may occur during perforation, deviations on width and length may be larger than rolling mill tolerances appropriate to the unperforated material supplied. The tolerances in Table 2 do not then apply. 5.4 Squareness (see Figure 3) The departure from squareness, c, generally referred to as the “amou

29、nt out-of-square”, of cut perforated metal plates is quantified by the orthogonal projection of a transverse edge (plate width a 1 ) onto a longitudinal edge (plate length b 1 ). It is expressed as a percentage of a 1 . Percent out-of-square = The tolerances on squareness are given in Table 3. 5.5 W

30、idth of margins (see Figure 2) The tolerances on the width of margins e and f are given in Table 4. Table 1 Symbols used to describe perforated metal plate 100c a 1 - Symbol Interpretation Figure reference a 1 overall length of the short side of a plate (plate width) Figure 2 a 2 length of the short

31、 side of the perforated area of a plate Figure 2 b 1 overall length of the long side of a plate (plate length) Figure 2 b 2 length of the long side of the perforated area of a plate Figure 2 c amount out-of-square of a rectangular plate Figure 3 e width of the margins on the long sides of a plate Fi

32、gure 2 e 1 width of the larger e-margin, if not equal Figure 2 e 2 width of the smaller e-margin, if not equal Figure 2 f width of the margins at the short sides of a plate Figure 2 f 1 width of the larger f-margin, if not equal Figure 2 f 2 width of the smaller f-margin, if not equal Figure 2 g dev

33、iation from edge flatness Figure 5 h deviation from edge straightness Figure 6 p pitch of holes Figure 1 t plate thickness Figure 2 t 1 height of turn-in zone of hole Figure 4 t 2 height of cutting zone of hole Figure 4 t 3 height of breakaway zone of hole Figure 4 t 4 height of burr on hole Figure

34、4 w hole size, measured on punch side Figure 1 w b hole size, measured on reverse (burr) side Figure 4BS7792:1995 BSI 10-1999 3 Table 2 Tolerances on width and length Table 3 Tolerances on squareness Table 4 Tolerances on width of margins 5.6 Flatness The tolerances on the flatness of perforated met

35、al plates, roller-levelled after perforation, as given in Table 5, apply for plates with a maximum length of 2 000 mm; with margins not exceeding plate thickness t +0,5p; and with open areas in the range of20% to40%. For perforated metal plates outside these limits, or with unperforated areas, the t

36、olerances on flatness shall be agreed before ordering. 6 Test procedure 6.1 Hole size and pitch (see Figure 1) Measure the hole size and pitch according to ISO7805-1 or ISO7805-2, depending on the plate thickness. The measurements shall be taken on the punch side of the plate. 6.2 Plate width and le

37、ngth (see Figure 2) Measure the plate width and length with a scale graduated in millimetres. For dimensions of300mm or less, a vernier calliper may be employed. Take the measurement over the entire thickness t. 6.3 Squareness (see Figure 3) If applicable, determine the squareness of cut perforated

38、metal plates by measuring the plate width and length and the amount out-of-square c according to5.4 and6.2. Identify the dimension c with the aid of a try square. 6.4 Flatness Place the plate, punch side uppermost, on a flat reference surface, e.g.a table with a smooth and even top. Use a scale, gra

39、duated in millimetres, which does not flatten the plate, to measure the distance from the highest point of the plate to the reference surface. 7 Irregularities caused by the perforating process 7.1 Breakaway on holes (see Figure 4) When the punch has penetrated deeply into the metal plate from the p

40、unch side, material will begin to tear, or break away, mainly from the reverse side of the plate. It is not possible to predict the precise shape and dimensions of the breakaway zone, but its height t 3does not usually exceed two-thirds of the plate thickness t. The width of the breakaway w bis roug

41、hly related to the plate thickness t and does not usually exceed the nominal hole size w by an amount of0,15t. 7.2 Burrs on holes and shearing burrs (seeFigure 4) Burrs will occur during both the perforating and the cutting (shearing) operations. Dimensions in millimetres Nominal width or length a 1

42、or b 1 Tolerance on a 1or b 1for nominal plate and thickness t t u 3 3 25 % 10 5 p u 20 10 20 p 0,5 pBS7792:1995 4 BSI 10-1999 Table 5 Tolerances on flatness While burrs on holes occur on the reverse side of the plate only, shearing burrs may occur on either the punch side or the reverse side, depen

43、ding on the manufacturing procedure adopted. Not more than10% of the number of holes or10% of the length of a cut edge of a perforated metal plate shall have burr heights in excess of the values stated in Table 6. Measure the burrs on holes with a depth micrometer and the shearing burrs with a verni

44、er calliper. Table 6 Maximum height of burrs 7.3 Wavy edge (see Figure 5) Stresses during perforation can distort the plate and cause variations in flatness in the margin areas, producing a so-called “wavy edge”, particularly if the margins on opposite sides are greater than the plate thickness t +0

45、,5p. The maximum permissible deviation from the flatness of edges g shall be agreed before ordering. 7.4 Edge bow (camber) (see Figure 6) Stresses during perforation and subsequent roller levelling processes can distort the plate, producing curving of the edges (edge bow/camber), particularly if the

46、 longitudinal margins e 1and e 2are unequal and parallel to the direction of perforation. Edge bow is defined as the greatest deviation h of the edge from a straight line extending over the length of the concave side and shall be measured with the aid of a straightedge of sufficient length having a

47、scale graduated in millimetres. The maximum permissible edge bow shall be agreed before ordering. 7.5 Missing holes (see Figure 7) Punches may break during the perforation process and fail to perforate in certain positions. The number of holes missed for this reason should not exceed5% of the total

48、number of holes in a perforated plate. When a multitool punch is used, it may not be possible to complete the pattern of perforations. For example, to minimize tool damage, punches of diameter less than5mm are usually spaced wider apart than the pitches of the holes. This arrangement, however, unavo

49、idably results in missing holes in one or more rows at both ends of the plate (incomplete rows). 8 Surface characteristics 8.1 Surface finish Slight damage of the perforated metal plate by mechanical action during the perforation process cannot be excluded. If this is detrimental to the proposed use, the purchaser should consult with the manufacturer before ordering. 8.2 Cleanliness Perforated metal plates are usually supplied with a light oily film. There should be no excessive seepage of oil after stacking