1、DEUTSCHE NORM October 1994 Countersunk flat head screws Penetration depth of cross recesses English version of DIN EN IS0 7721-2 (IS0 7721 -2 : 1990) This standard incorporates the English version of Is0 7721 -2. ICs 21.060.1 O Descriptors: Fastener, screw, countersunk head screw, cross recessed hea
2、d, dimensions. Senkschrauben. Teil 2: Eindringtiefen von Kreuzschlitzen (IS0 7721-2 : 1990) European Standard EN IS0 7721-2: 1994 has the status of a DIN Standard. A comma is used as the decimal marker. National foreword This standard has been published in accordance with a decision taken by CENTTC
3、185 to adopt, without alteration, International Standard IS0 7721 -2 as a European Standard. The responsible German body involved in its preparation was the Normenausschu Mechanische Verbindungselemente (Fasteners Standards Committee). The main purpose of this standard is to specify the penetration
4、depth of the cross recess of countersunk flat head screws of property class 8.8 so as to satisfy the requirement for sufficient head strength. This can be ensured by providing either a shallower penetration depth (though this may adversely affect wrenchability) or an underhead shoulder (cf. The DIN
5、Standards corresponding to the International Standards referred to in clause 2 and Annex A of the DIN EN IS0 are as follows: IS0 Standard DIN Standard IS0 225 DIN EN 20225 IS0 4757 DIN EN IS0 7046-2). DIN EN IS0 4757 IS0 7046-1 IS0 7046-2 DIN EN IS0 7046-1 DIN EN IS0 7046-2 IS0 7721 DIN EN 27721 Sta
6、ndards referred to (and not included in Normative references and Annex ZA) DIN EN 20225 Fasteners; bolts, screws, studs and nuts; symbols and designations of dimensions DIN EN 27721 Countersunk head screws; head configuration and gauging DIN EN IS0 4757 Cross recesses for screws DIN EN IS0 7046-1 Co
7、untersunk flat head screws (common head style) with type H or type Z cross recess (product grade A); steel of property class 4.8 DIN EN IS0 7046-2 Cross recessed countersunk flat head screws (common head style) (grade A); steel of property class 8.8, stainless steel and non-ferrous metals Internatio
8、nal Patent Classification F 16 B 023/00 EN comprises 6 pages. suth Veflag GmbH, Berlin, has the exclusive right of sale for German StandardspIN-Normen). DIN EN IS0 7721-2 End. Price WOUD - -. 03.95 Sales No. 1106 EUROPEAN CTANDARD NORME EUROPENNE EUROPAISCHE NORM EN IS0 7721-2 July 1994 UDC 621.882.
9、215.6.091.6 Descriptors: Fastener, screw, countersunk head screw, cross recessed head, dimensions. English version Countersunk flat head screws Part 2: Penetration depth of cross recesses (IS0 7721 -2 : 1990) Vis mtaux tte fraise. Partie 2: Profondeur de pntration des empreintes cruciformes Senkschr
10、auben. Teil 2: Eindringtiefen von Kreuzschlitzen (IS0 7721-2: 1990) (IS0 7721-21990) This European Standard was approved by CEN on 1994-07-26 and is identical to the IS0 Standard as referred to. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipu- late the conditions
11、 for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three offic
12、ial versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, B
13、elgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de S
14、tassart 36, B-1050 Brussels O 1994. Copyright reserved to all CEN members. Ref. No. EN IS0 7721 -2 : 1994 E Page 2 EN IS0 7721 -2 : 1994 Foreword International Standard IS0 7721-2: 1990 has been taken over as a European Standard by Technical Committee CEN/TC 185 Threaded and non-threaded mechanical
15、fasteners and accessories from the work of ISOTTC 2 Fasteners of the International Organization for Standardization (ISO). This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, and conflicting national standards withdra
16、wn, by January 1995 at the latest. In accordance with the CENKENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sw
17、eden, Switzerland and United Kingdom. Countersunk flat head screws: penetration depth of cross recesses Endorsement notice The text of the International Standard IS0 7721 -2 : 1990 was approved by CEN as a European Standard without any modi- fication. Page 3 EN IS0 7721-2: 1994 Introduction The pene
18、tration depth of cross recesses for countersunk flat head screws has to satisfy two requirements which act in opposite directions for a given head dimension. First, there is the requirement for suffcient head strength to attain the proof and breaking loads of the respective property class. A shallow
19、 cross recess increases the head strength. On the other hand, the wrenchability of the screw should be satisfactory: this can only be achieved by a sufficiently deep cross recess. IS0 7721-2 was developed in order to find a compromise which, as far as possible, would meet both requirements. This par
20、t of IS0 7721 specifies deep cross recesses for countersunk head screws of low strength: a good wrenchability is achieved and the head strength is still sufficient. This execution will be used in IS0 7046-i (see annex A). For screws of higher strength, sufficient head strength can only be at- tained
21、 by a shallower penetration depth of the cross recesses. If such screws also require good wrenchability, then, under the conditions of the common head style, a shoulder has to be provided under the head, in addition to the larger penetration depth, in order to guarantee suffi- cient head strength. T
22、his compromise, which unfortunately results in different but inter- changeable types of cross recessed flat countersunk head screws, is at the moment the only way of reaching an agreement at the international level. Page 4 EN IS0 7721 -2 : 1994 1 Scope This pari of IS0 7721 specifies the pen -tratio
23、n depth of cross recesses of countersunk flat head screws for the two series I and 2 (deep and shallow, re- spectively). 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this pari of IS0 7721. At the time of publication
24、, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of IS0 7721 are encouraged to investi- gate the possibility of applying the most recent edi- tions of the standards indicated below. Members of IEC and IS0 maintain registers of c
25、urrently valid International Standards. IC0 225:1983, Fasteners - Bolts, screws, studs and nuts - Symbols and designations o dimensions. IS0 4757:1983, Cross recesses for screws. IS0 7721:1983, Countersunk head screws - Head configuration and gauging. 3 Dimensions For application of the penetration
26、depths of cross recesses specified in table 1, different underhead configurations are provided in order to attain suffi- cient head strength (see figure 1 and figure2). Both types salisly the conditions of the common head style as specified in IS0 7721). NOTE 1 specified in IS0 225. Symbols and desi
27、gnations of dimensions are a, = 2,s P Figure 1 - Screw with underhead shoulder amax = 2 P Figure 2 - Screw without underhead shoulder 1) Will be revised and published under number IS0 7721-1 Page 5 EN IS0 7721 -2 : 1994 Table 1 - Dimensions Dimensions In millimetres Recess No. I) Thread I I Metric I
28、 Other ST53 3 M6 ST63 3 sT8 4 H10 4 Application 3) Series 0,6 0,9 1,6 0.9 1.2 1,9 0,9 1,2 1,9 with IS0 4757. 2) Penetration depth measured In accordance with IS0 4757. I I 4, 4,6 8,9 I I Type Z Penetratlon de th*) min. 9 max. 1 rei. 0,s 1,20 1,48 I 1,73 I 2,8 1.76 I 2,Ol I 3 2,73 I 3,18 I 6,3 3,OO 3
29、.45 6,6 4.15 4,60 0,8 5,19 5,64 9, Screws without underherd shoulder Self-tapplng screws Wood screws Screws of property class 4.8 Screws with underhead shoulder Screws of property classes 0.8 and 9.8 Thread cultlng screws Thread forrnlng screws cesses Series 2 Penetr2EHl rni,4“qm,x. rei. - I - I - 1
30、,25 I 1,55 I 2,7 1 I 2,3 I 2,8 I 4,8 :hailow) Penetratlon 0.95 I 1,20 I 1,9 -1-1- 1,22 I 1,47 I 2,5 1,48 I 1.73 1 2,8 1,61 2.05 4 2,73 I 3,18 I 6.3 3,87 I 4,32 I 8,5 I I Screws without underhead shoulder entirely heat Screws of property Thread forming screws Thread cuttlng screws class 8.8 1) Cross
31、recesses In accordance 3) Specified for steel screws, appiicatlon for other materials at manufacturers option. Page 6 EN IS0 7721 -2 : 1994 Annex A (informative) Bibliography I IS0 7046:1983, Cross recessed countersunk flat head screws (common head sfyle) - Product grade A and 2 IS0 7046-21990, Cros
32、s recessed countersunk flat head screws (common head style) - Grade A - Part 2: property class 4.8 only.* Steel of property class 8.8, stainless steel and non-ferrous metals. Annex ZA (normative) Normative reference to international publications with their relevant Europn publiciiths mis European St
33、andard inarporrites by diilcd or undiiied rccrcncc. provisions from other publications. These normative references are cittd iit the appropriate pliccs in the texi and the publications are listed hereafter. For dated references. subsqueni amendmcnts to or revisions of my of these publications apply
34、to this European Standard only when incorporaid in i by amcndmcnt or revision. For undated references the latest edition of the publication refcrnd IO zipplies (including iimendmcnts). Publication Year Title ENIHD - Y ear Is0 225 1 Y83 Fasteners - Bolts. scruvs. siudsSymbols iind EN 20225 1991 designation of dimmions Is0 7721 1983 Countersunk head scmvs - Head configuriiiion and EN 27721 1991 gauging 2) Will be revised and published under number IS0 7048-1.
