International Standard

Transcription

1 International Standard 4757 Cross recesses for screws Empreintes cnrciformes pour v First edition Wl UDC f Ref. No. IS (E) Descriptors : fasteners, screws, cruciform recessed screws, dimensions. -J i >? Price based on 9 pages

2 Th do Foreword n me cu IS0 (the International rganization for Standardization) a worldwide federation of national standards bodies (IS0 member bodies). The work of developing International Standards carried out through IS0 technical committees. Every member body interested in a subject for which a technical committee has been authorized has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaon with IS, also take par? in the work. t Draft International Standards adopted by the technical committees are circulated t o the member bodies for approval before their acceptance as International Standards by the IS0 Council. ap vie re International Standard I S was developed by Technical Committee IS/TC 2, Fasreners, and was circulated to the member bodies in December 98. It has been approved by the member bodies of the following countries: Norway Poland Romania South Africa, Rep. of Spain Sri Lanka Sweden Switzerland S EV United Kingdom of the document on by The member body of the following country expressed dapproval technical grounds: ted USA USSR ra ne ge Germany, F.R. Hungary India Ireland, Italy Japan Korea, Dem. P. Rep. of Korea, Rep. of Mexico Netherlands New Zealand w Australia Austria Belgium Brazil Canada China Czechoslovakia Denmark Egypt, Arab Rep. of Finland International rganization for Standardization, 983 Printed in Switzerland

3 I N TE R N AT NA L STAN DAR D IS (E) Cross recesses for screws Scope and field of application Th International Standard defines two types of cross recesses for screws: - recess type H; - recess type 2. Th document a preview generated by EVS Included in th International Standard a method of penetration gauging for both types.

4 2 Recess type H 2. Dimensions c Th document a preview generated by EVS c- c B-B 2

5 IS (E) Table - Recess type H Dimensions in millimetres ) Th will be replaced by r min mm; r max mm Dimensions shown are theoretical values. Th document a preview generated by EVS 2.2 Recess penetration gauging and gauge dimensions for recess type H The penetration depth of the depth gauge (minimum dimension) indicated in the different product standards. It the test dimension for the usability of the cross recess. The point of the gauge identical with the point of the respective screwdriver. A sleeve serves to guide the gauge and fix the reference plane. Th plane passes through the point of intersection of the recess wings and the top surface of the screw head. It corresponds thus to the surface of a screw with flat head. In the case of crowned screw heads, it lies below the crown in the transition area from the recess wings to the surface of the head. For these screw heads, the reference plane fixed with the help of the bearing surfaces of the gauge sleeve. The penetration depth of the gauge measured from the reference plane by using a dial gauge. The zero and control positions of the depth gauge can be found on a flat surface. Due to the permsible error for the core thickness b of the gauge point, an inaccuracy of up to 0.3 mm can are when measuring the penetration depth. 3

6 IS (E) Th document a preview generated by EVS Gauge Reference plane I L Zero position LT Control position 4

7 I S (E) Th nt me cu do &Minimum length of true form re ap vie I , ted b - Gauge dimensions for recess type H ra Gauge No. ne ge Table 2 A-A w C 5.08 by S EV Th will be replaced by r = 0,25 t 0,025 mm. 5

8 IS (E) 3 Recess type Z 3. Dimensions c-c Th document a preview generated by EVS / 6

9 I S (E) Th do nt me cu Recess g ,s s -npt max. max. + 5 B Y , ,34 3,s , , , , , ted Dimensions shown are theoretical values.,= ra d - 5 0,l ne 2 j ge max Dimensions in millimetres iew a 0.76 ev f No. Recess type 2 pr b - a Table 3 by S EV 7