1、CEN PRENw365B 92 m 3404589 0023305 9 A. E.C. M.A. STAN DARD NORME A.E.C.M.A. A.E.C.M.A. NORM prEN 3658 Issue P 1 January 1992 EDITE PAR LASSOCIATION EUROPEENNE DES CONSTRUCTEURS DE MATERIEL AEROSPATIAL Technopolis - 175, rue Jean-Jacques Rousseau - F-92138 Issy-les-Moulineaux Cdex -Tl. (1) 47.36.98.
2、76 UDC Key words : ENGLISH VERSION Aerospace series Tube bend radii, for engine application Design Standard Srie arospatiale Rayons de cintrage des tubes, pour application moteurs Norme de conception Luft- und Raumfahrt Biegeradien von Rohren, fr Triebwerlcsanwendung Konstruktionsnorrn This .Aerospa
3、ce Series: pre-standard has been drawn up under the responsibility of AECMA (Association Europenne des Constructeurs de Matriel Arospatial). It is published on green paper for the needs of AECMA-Members. It has been technically approved by the experts of the concerned Commission following comment by
4、 the Member countries. Subsequent to the publication of this pre-standard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and signature of the AECMA Standard Checkin
5、g Centre (NPS) and formal agreement of the Official Services of the Member countries it will be submitted as a draft European Standard to CEN (European Committee for Standardization) for final vote. Nota - Extra copies cai iie siipiiiied by B.N.A.E. - Techiiopoiis 54 - 199. riie Jeaii-Jacques Rousse
6、au - 92138 ISSY-LES-MOULINEAUX CEDEX Edition approved for publication 1992-01 -31 Comments should be sent within six months after the date of publication decision A.E.C.M.A. Techiiopolis - 175, rue Jean-Jacques Rousseau 921 38 Issy-les-Moulineaux Cdex - FRANCE C8 Chairman Mr. WILLIAMS 0 aecma 1992 C
7、EN PRENu3658 92 3404589 0023306 O prEN 3658 Page 3 1 Scope and field of application This standard provides details of bend radii used in the manufacture of rigid tubes. It also provides details of the minimum length of straight permissible between such radii during manufacture. 2 Applicability This
8、standard applies to rigid tubes conforming to EN 3717 and produced only in AECMA materials. 3 Reference EN 371 7, Aerospace series - Tubes - Selection for engines fluid systems 4 Purpose To lay the foundations for rigid tube design. 5 Design features and considerations 5.1 To allow an unbroken seque
9、nce of bending operations, all bends in a given tube configuration, should have the same radius. 5.2 tube diameter. The standard bend radius measured to the centre line of the tube has been fixed for each 5.3 must lie in one plane only as shown on figure 1, Bend radii are based on 2,5 D for steel an
10、d 3 D for titanium. Standard bend radii using a range of preferred tube sizes are given in table 1. Bend radii 5.4 The distance between bends in a tube configuration shall be sufficient to facilitate mandrel bending. This requires a straight length to accommodate clamp widths. Minimum lengths quoted
11、 in table 2 should be exceeded wherever possible. 5.5 During bending the wall thickness of the outer side of the bend is reduced (see figure 2). The acceptable minimum wall thickness T1 after bending shall not be less than 90 % of the nominal wall thickness T. 5.6 Ovality may be defined as the diffe
12、rence between the maximum and minimum diameters of a tube at any section normal to the axis (see figure 3). The maximum ovality acceptable at any section of the tube after bending, measured normal to the axis, shall not exceed 10 % of the nominal tube outside diameter. 6 Dimensions 6.1 All dimension
13、s are in millimetres. 1) Published as AECMA pre-standard at the date of publication of the present standard t . CEN PREN83658 92 = 3404589 0023307 2 prEN 3658 Page 4 I Radius Y to lie in one plane only Radius Y (based on 2,5 D for steel diameter of the tube) and 3 D for titanium where D = Outside Fi
14、gure 1 Table 1 Tube outside Radius “ Y “ diameter Steel I Titanium 4 I 10 I 12 5 123 15 8 20 24 9 22,5 27 10 25 30 11 27.5 33 12 30 36 14 35 42 15 37,5 45 37.5 18 45 54 20 50 60 22 55 66 r 25 62,5 75 28 I 70 I 84 32 80 96 I 36 l 90 108 1 40 1 O0 120 45 11 2,5 135 50 125 150 CEN PREN*3658 92 3404589
15、0023308 4 m diameter 4 to 50 prEN 3658 Page 5 used for mandrel bending Length equal to 3 x tube - Figure 2 Table 2 I Tube outside I Minimum length “ Z “ CEN PRENx3b58 92 m 3404589 0023309 b m prEN 3658 Page 6 e-T 5 I. g R Figure 2 T Before bending D = Nominal tube outside diameter R = Bending radius T = Nominal wall thickness TI = Minimum wall thickness after bending After bending % ovality = D max. - D min. X 100 D D min. Figure 3
