BS 8726-1:2002
$167.15
Cylindrical helical springs made from rectangular and square section wire and bar. Guide to calculation and design – Compression springs
| Published By | Publication Date | Number of Pages |
| BSI | 2002 | 34 |
This British Standard provides guidance on the design of parallel sided helical compression springs manufactured from rectangular and square section wire and bar.
This standard applies only to springs made from rectangular section material where the ratio of radial dimension, b, to the axial dimension, h, termed the shape factor, m, is not greater than 2.5 and not less than 0.4.
NOTE 1 This applies because, outside the shape factor range 2.5 to 0.4, it is difficult to coil a spring accurately.
NOTE 2 There are numerous methods of calculating the parameters necessary for the design of springs and initially the designer is free to use any one of these.
Three types of end coils are provided for, i.e. open end, closed end and closed and ground end, the last of these being applicable only to springs where the axial dimension of material is 0.5 mm or greater.
This British Standard differentiates between springs that have or have not been stress relieved after forming, designated group A springs, and springs, the material of which has undergone a structural change by heat treatment after forming, designated group B springs.
This British Standard gives two methods of specifying springs for general purposes and one method of testing springs.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 1 | BRITISH STANDARD |
| 2 | Committees responsible for this British Standard |
| 3 | Contents |
| 5 | 1 Scope 2 Normative references 3 Terms, definitions and symbols 3.1 Terms and definitions 3.1.1 active coils |
| 6 | 3.1.2 angle of grind 3.1.3 bow 3.1.4 buckling 3.1.5 chamfering 3.1.6 closed end 3.1.7 compression spring 3.1.8 compression test 3.1.9 coning 3.1.10 countersink 3.1.11 cramp test 3.1.12 creep 3.1.13 damper coils 3.1.14 dead coils 3.1.15 deflection |
| 7 | 3.1.16 edge dressing 3.1.17 elastic deformation 3.1.18 seating coefficient 3.1.19 fatigue 3.1.20 fatigue limit 3.1.21 fatigue strength 3.1.22 fatigue test 3.1.23 finish 3.1.24 fitted length 3.1.25 free length 3.1.26 grinding 3.1.27 group A springs 3.1.28 group B springs |
| 8 | 3.1.29 hand 3.1.30 heat stabilization 3.1.31 helical spring 3.1.32 helix angle 3.1.33 hysteresis 3.1.34 index 3.1.35 inside coil diameter of a spring 3.1.36 linearity 3.1.37 load test 3.1.38 modulus of elasticity 3.1.39 natural frequency 3.1.40 open end 3.1.41 outside coil diameter 3.1.42 parallelism |
| 9 | 3.1.43 permanent set 3.1.44 pitch 3.1.45 prestressing 3.1.46 rate 3.1.47 relaxation 3.1.48 residual range 3.1.49 safe deflection 3.1.50 shot peening 3.1.51 solid length 3.1.52 solid force 3.1.53 space |
| 10 | 3.1.54 spring seat 3.1.55 squareness 3.1.56 stress 3.1.57 stress correction factor 3.1.58 stress range 3.1.59 stress relieving 3.1.60 stroke 3.1.61 vapour blasting 3.1.62 variable pitch spring 3.1.63 variable rate spring |
| 11 | 3.2 Symbols |
| 12 | 4 General 5 Methods of calculation 5.1 Stress correction factor 5.2 Stress 5.3 Rate 5.4 Natural frequency |
| 13 | Figure 1 – Design chart for stress |
| 14 | Figure 2 – Design chart for rate 5.5 Buckling |
| 15 | Figure 3 – Seating coefficient v for various end conditions 5.6 Number of coils 5.7 Solid length |
| 16 | 5.8 Effect of coating thickness on spring rate Figure 4 – Critical relative deflection for |
| 17 | Figure 5 – Critical relative deflection for |
| 18 | 6 Tolerances 6.1 General 6.2 Dimensional tolerances |
| 19 | 6.3 Property tolerances |
| 20 | Table 1 – Calculated tolerances for group A springs with more than 3.5 and less than 5 total coils Table 2 – Calculated tolerances for group B springs with more than 3.5 and less than 5 total coils 7 Specifying springs for general purposes 7.1 Introduction |
| 21 | 7.2 Method one (customer design) using Data Sheet 1 |
| 22 | Figure 6 – Data sheet 1 |
| 23 | Figure 7 – Hand of coiling Figure 8 – End coil form Figure 9 – Coil end formed from tapered bar |
| 25 | 7.3 Method two (application for spring design) using Data Sheet 2 |
| 27 | Figure 10 – Data sheet 2 |
| 28 | 8 Methods of verification 8.1 General 8.2 Dimensional verification |
| 29 | Figure 11 – Measurement of free length and parallelism |
| 30 | Figure 12 – Measurement of squareness Figure 13 – Measurement of bow |
| 31 | 8.3 Property verification 8.4 Performance verification |
| 33 | Annex A (informative) Modulus of rigidity of some materials Table A.1 – Modulus of rigidity values Annex B (informative) Typical tolerances on rectangular section material Table B.1 – Typical tolerances on rectangular section material |
