1、 STD-AECMA PREN 38q-ENGL L77b LOL23LL 0032728 225 Edition approved for publication AECMA STANDARD NORME AECMA AECMA NORM C6 Chairman Comments should be sent within six months after the date of publication to prEN 3848 Edition P 2 October 1996 PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE INDUST
2、RIES (AECMA) Gulledelle 94 - 8-1200 BRUXELLES - Tel. (32) 2 775 81 10 - Fax. (32) 2 775 81 11 ICs : ENGLISH VERSION Aerospace series Semi-finished metallic products Methods of measuring form deviations Supersedes edition P 1 September 1994 Srie arospatiale Demi-produits mtalliques Mthodes de mesure
3、des dfauts de forme Luft- und Raumfahrt Metallisches Halbzeug Meverfahren fr Formabweichungen This “Aerospace Series“ Prestandard has been drawn up under the responsibility of AECMA (The European Association of Aerospace Industries). It is published on green paper for the needs of AECMA-Members. It
4、has been technically approved by the experts of the concerned Technical Committee following comment by the Member countries. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, wit
5、hout re-identification of the standard. After examination and signature of the AECMA Standard Checking Centre (NPSI 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 formal vote.
6、 1996-10-31 AECMA Gulledelle 94 B-1200 BRUXELLES Mr Grgoire I I I aecma 199 Page 3 prEN 3848 : 1996 I Scope This standard specifies the methods of measuring deviations from the nominal form of semi-finished metallic products for aerospace applications. This standard does not apply to : - extruded se
7、ctions : see EN 2066 ; - folded sections : see EN 2065. 2 Normative references This European Standard incorporates by dated or undated reference provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. F
8、or dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 2065 Folded profiles aluminium alloys -
9、General tolerances - Aerospace series 1) EN 2066 Extruded sections in aluminium and aluminium alloys - General tolerances - Aerospace series 1) 3 Measuring condition The dimensions shall be measured using measuring instruments which are of the accuracy required by the dimensions and the dimensional
10、tolerances. All dimensions shall be checked at the ambient temperature of the workshop or laboratory, and, in the event of dispute, at a temperature between 15 OC and 25 OC. Deviation from flatness of the base plate shall be less than the flatness tolerance for the product being checked. 4 Sheet and
11、 plate 4.1 Squareness The squareness deviation shall be measured as the difference in length of diagonals AA and BB as shown in figure 1. 4.2 Lateral Curvature The lateral curvature (FI shall be measured as indicated in figure 2, with the sheet or plate resting on a horizontal base plate. 4.3 Flatne
12、ss Deviation from flatness VI resulting from arching, buckling or edge waves, shall be measured as shown in figures 3 to 6, using a lightweight straight-edge and a feeler gauge, dial gauge or scale, with the sheet or plate resting on a horizontal base plate concave side upwards, except when the size
13、 of the product precludes this. 1) Published as AECMA Standard at the date of publication of this standard Page 4 prEN 3848 : 1996 5 Round bar 5.1 Straightness Deviation from straightness (YI) per metre of total length (XI), expressed in mm/m, and (Y21 on any length (X2), as specified in the dimensi
14、onal standard, shall be measured as shown in figure 7, with the bar placed on a horizontal base plate so that its mass minimizes the deviation. 5.2 Roundness Roundness deviation shall be measured as the difference between the maximum and minimum diameters at the same cross-section. 6 Hexagonal bar 6
15、.1 Straightness Deviation from straightness (YI) per metre of total length (XI), expressed in mm/rn, and (Y21 on any length (Xz), as specified in the dimensional standard, shall be measured as shown in figure 7, with the bar placed on a horizontal base plate so that its mass minimizes the deviation.
16、 6.2 Twist Twist (v) shall be measured as shown in figure 8, with the bar placed on a horizontal base plate so that its mass minimizes the deviation. Twist is the maximum distance, at any point along the measuring length between the bottom surface of the bar and the base plate surface. 6.3 Surface f
17、latness Surface flatness (F) shall be measured on all faces as shown in figure 9. 7 Square and rectangular bar 7.1 Straightness Deviation from straightness (YI) per metre of total length (XI), expressed in mm/m, and (Y21 on any length (Xz), as specified in the dimensional standard, shall be measured
18、 as shown in figure 7, with the bar placed on a horizontal base plate so that its mass minimizes the deviation. 7.2 Twist Twist (v) shall be measured as shown in figure 10, with the bar placed on a horizontal base plate so that its mass minimizes the deviation. The twist is the maximum distance, at
19、any point along the measuring length between the bottom surface of the bar and the base plate surface 7.3 Squareness The squareness deviation (2) shall be measured as shown in figure 1 1. 7.4 Surface flatness Surface flatness (F) shall be measured on all faces as shown in figure 12. Page 5 prEN 3848
20、 : 1996 8 Circular tube 8.1 Straightness Deviation from straightness (Y,) per metre of total length (XI), expressed in mm/m, and (Y21 on any length (Xz), as specified in the dimensional standard, shall be measured as shown in figure 7, with the tube placed on a horizontal base plate so that its mass
21、 minimizes the deviation. 8.2 Roundness Roundness deviation shall be measured as the difference between the maximum and minimum outside diameters at the same Cross-section, see figure 13. 8.3 Eccentricity Eccentricity (t) shall be measured as half the difference between the maximum and the minimum w
22、all thickness at the same cross-section, as shown in figure 14. Figure 1 : Squareness of sheet and plate Side edqe (concave side) / I / F S traight-edge lorb F : lateral curvature : length of the sheet or plate b : width of the sheet or plate Figure 2 : Lateral curvature of sheet and plate _ _ STD-A
23、ECMA PREN 3848-ENGL 397b 301233L 0032732 75b Page 6 prEN 3848 : 1996 S traight-edge f : deviation from flatness b : width of the sheet or plate Figure 3 : Transverse arching of sheet and plate S traight-edge I - f 1 f : deviation from flatness Figure 4 : Longitudinal arching of sheet and plate : len
24、gth of the sheet or plate S traight-edge T f : deviation from flatness W : length of buckle (chord) Figure 5 : Buckling of sheet and plate Straight-edge -l* Base plate TI I f : deviation from flatness W : length of edge wave (chord) Figure 6 : Edge waves of sheet and plate Base plate Page 7 prEN 384
25、8 : 1996 Base plate Straigh t-edge 1 I Y1 : deviation from straightness on total length XI Y2 : deviation from straightness on length X2 Figure 7 : Deviation from straightness of bar and tube ,- Baseplate v : twist a : across flat of the bar Figure 8 : Twist of hexagonal bar Side edge (concave face)
26、 Straight -edge I LL F : deviation from surface flatness a : across flat of the bar Figure 9 : Surface flatness of hexagonal bar STD-AECMA PREN 38VB-ENGL 177b 1012311 0012739 527 - Straigh t-edge Page 8 prEN 3848 : 1996 F 1 -4 c O r- Side edge (concave face) / Base plate P O - v : twist a : thicknes
27、s of the bar Figure 10 : Twist of square and rectangular bar z : squareness deviation Figure 11 : Squareness deviation of square and rectangular bar F : deviation from lateral flatness a : thickness of the bar b : width of the bar Figure 12 : Surface flatness of square and rectangular bar STD=AECMA
28、PREN 3848-ENGL L97b LOL23LL 0032435 Lib5 Page 9 prEN 3848 : 1996 Roundness deviation = Dmax. - Dmi“. D,. : maximum outside of the tube Dmin. : minimun outside of the tube Figure 13 : Roundness of the tube II t : eccentricity amax. : maximum wall thickness of the tube amin. : minimum wall thickness of the tube amax. - amin. 2 t= Figure 14 : Eccentricity of tube
