FR2631406A1 - METHOD FOR MANUFACTURING A PACKET OF BLADE SPRINGS HAVING A NUMBER OF SPRINGS-BLADES OF DIFFERENT LENGTHS - Google Patents

Abstract

Method of manufacturing springs. To make a leaf spring package, we first calculate a template leaf spring package with the same number of leaf springs (n = 1 ... i) and the template leaf springs serving as templates for sizing leaf springs of the leaf spring package to be manufactured; each leaf spring to be manufactured is calculated from the predetermined length l2, width b2 or thickness h2 of the longest leaf spring to be manufactured for the dimensions, and starting from this model leaf spring (index 1 ) and the leaf spring to be manufactured (index 2), we determine the ratio L = l1 / l2 of the lengths of the leaf springs, B = b1 / b2 of the width of the leaf springs, the ratio H = h1 / h2 of the thickness of the leaf springs, the ratio E = E1 / E2 of the modulus of elasticity and the ratio C = C1 / C2 of the spring coefficients, as well as by calculation according to the formula C = EH ** 3.B / L ** 3 and on the basis of the ratios thus determined, each further leaf spring is calculated, and, on the basis of these values, the desired leaf spring packs are produced. The invention relates to the manufacture of leaf springs for suspension.

Description

A method of manufacturing a package of leaf springs having a number

  The present invention relates to a method of manufacturing a package of leaf springs comprising

  a number n of leaf springs of different lengths

  are arranged in a staggered manner and pressed against each other in the middle of their length and clamped together, a bundle of leaf springs resting at both ends of the longest leaf spring against an element to be suspended as example

a motor vehicle.

  The usual calculation of spring packs-

  Blades is based on the assumption that all sections

  superimposed leaf springs present the same flam-

  bage. This hypothesis is only a crude approach to real conditions and does not allow for this

  reason to use the material optimally.

  The object of the present invention is therefore to create a method of manufacturing a package of leaf springs which, in combination with the following first principles, namely: a) a total spring coefficient, determined

  (b) a length and width or thickness

  the longest leaf spring.

  c) the same material and the same modulus of elasticity E for all leaf springs, d) leaf springs which are in contact with each other and each time in the median clamping area and at the fulcrums, (e) the thickness of a leaf spring must be equal over the entire effective length, and (f) the width of all leaf springs must be equal over the effective length to satisfy the condition that

  the induction of forces in the package of springs-

  blades the maximum voltage must be of the same amplitude

in all leaf springs.

  For this purpose, the invention relates to a method of the above type characterized in that to produce a package of leaf springs which must have a certain

  overall coefficient of spring and a number of

  blade-spells made of the same material having the same modulus of elasticity, a package of model leaf springs having the same number is first calculated

  of leaf springs and leaf springs models ser-

  of models for sizing leaf springs of the package of leaf springs to be manufactured, this calculation taking into account the following assumptions, namely: a) all model leaf springs are made of the same material having the same module elasticity, b) the model leaf springs touch each time at their fulcrum and in the central clamping zone, c) the thickness of a model leaf spring is the same throughout the effective length, d) all model leaf springs have the same width throughout the effective length, e) the tension is the same in all leaf springs

  between the points of support when a force is

  pick in the package of leaf springs,

  and in that each leaf spring to be manufactured is calculated

  the starting from the length, the width or the

  predetermined thickness of the longest leaf spring to be made, in terms of dimensions, starting from the order of numbering in the package of the similar model leaf spring, and starting from this model leaf spring (index

  1) and the leaf spring to be manufactured (index 2)

  mine the ratio L = - lengths of the springs-

  blades B = b1 / b2 of the width of the leaf springs, the ratio H = h1 / h2 of the thickness of the leaf springs, the ratio E = E1 / E2 of the modulus of elasticity and the ratio

  C-C1 / C2 spring coefficients as well as by cal-

ass according to the formula

C = E.H3.B / L3

  with transformation according to the sought values and corresponding substitution of the known quantities of the model leaf spring and the predetermined quantities

  and or for the missing dimensions or the spring-

  the blade to be made, and thus the relationships thus determined.

  mined, each other leaf spring is calculated and on the

  These values are based on these values.

desired spells. -

  According to another characteristic of the in-

  vention, each model leaf spring is calculated

  the formulas of the elastic line of a beam embedded in one side, the free end of which

  distance is subjected to a force P and which at the distance

  it is subjected to a force U of direction oppc3é to that of

  force, apply the following formulas:

  vantes: x2 x2 (VII) E.J.n = P. - (3.lb (n) - X) -U. - (3.1 (n) y-X)

6 6

X2 1

  (VIII) E.J.n = P. - (3-1b (n) -X) -U.- (3.X-la (n))

6 6

the s X s lb.

  According to another characteristic of the in-

  vention, the leaf spring, model, of dimensions

  vante, corresponding to the index (n + 1) satisfies the following conditions, namely: 1. at the location X = lb (n) = la (n +) it must have the same buckling as the calculated model leaf spring previously and corresponding to the index (n),

  2. between the embedding point and the point of

  by the model-order blade spring (n) calculated previously, the order-type leaf spring (n + 1) must have the same maximum marginal tension as the leaf spring (n) ,

  and in that the force P is equal to the force U and

  if the tension and moment of buckling are constant

in zone a, that is to say Xla.

  According to another characteristic of the in-

  vention, equations (vII) and (VIII) elastic lines (only for other lengths and other thicknesses of blades h (n +,)) as well as for the leaf spring model order (n + 1) next apply

  and the contact conditions give the following equation:

  vante: (Ix) i. PLb (n) (lb (n + 1) - lb (n) = E.h3 2 (n + 1)

3 2

  1 [P.lb (n) P * la (n) [6. (3-lb (.1) lb (.) _ - (3 - 1b (.) (N), E. h 6 6 (n) and the condition of identical marginal stresses gives the following equation: (X) P. (lb (n + 1) - lb (n)) P. (lb (n) - la (n)

2 2

(n +) h (n)

  equations in which the formula of the model is used.

  of surface inertia J = b.h3 / 12 and the moment

  where W = b.h2 / 6 corresponding to the rectangular section

supposedly of the leaf springs.

  According to another characteristic of the invention

  equations (IX) and (X) are resolved according to the

  two unknowns, namely, the length lb (n + 1j and the

  thickness h (n + 1) of the following model leaf spring in searches (n + 1) by the following equations:

(XI)

3. lb (n) (lb (n) - la (n)).

h (n + 1) = h (n) * 22

3 2 2

(2.Ib (n) - 3. 1 (n) lb (n) + la (n))

(XII)

  lb (n + 1) lb (n) + () * lb (n) - la (n)) -

  h (n) Thus, a package of model leaf springs corresponding to the ideal conditions is first calculated. From there, we calculate the dimensions of the leaf springs of a package of leaf springs to be realized

  then, on the basis of quantities thus obtained,

  naked. The method according to the invention will be explained below with reference to the drawings in which: FIG. 1 shows a recessed beam whose free end is loaded for calculating a half leaf spring, FIG. particularly

the process according to the invention.

  In a package of leaf springs, ideal,

  With a stack of leaf springs, by definition, the forces are transmitted from one leaf spring to the other.

  at the level of the respective ends of each

  out-blade. In addition, the length of the different leaf springs and the constant blade thickness are fixed over the entire length of each spring blade to have the same marginal tension in each leaf spring.

  maximum, to the free end of the blade.

  Then, for a package of leaf springs to

  realize, we first calculate a package of

  model blade-spells with the same number of springs-

  blades n = 1 .... i and which serves as a model.

  The calculation of this package of leaf springs

  is done taking into account the conditions explicitly

  hereafter: (a) all model leaf springs are made

  in the same material with the same elasticity

  E, b) the leaf springs of the model touch only at the fulcrums and in the middle clamping area, c) the thickness of a model leaf spring is the same everywhere over the entire effective length, d) all model leaf springs have the same width over the entire effective length, and e) the tension is the same in all model leaf springs between the bearing points when inducing

  a force in the package of model leaf springs.

  As a leaf spring behaves symmetrically with respect to its plane of symmetry when it is subjected to a force, it is possible to use for the calculation conditions relating to the leaf spring package, model, as the beginning of the calculation of the elastic line, a beam embedded on one side which, as shown in Figure 1, is loaded at the free end of the blade by a force P; in a second point

  (corresponding to the support provided by the

  model model directly below) the beam is subjected to a force U of opposite direction to the previous one.

  In this figure, the (n) represents the length

  free of the model leaf spring bearing the reference

  this (n) in the zone (a) between the central embedding point up to the point of application of the force U. The

  reference 1b (n) denotes the free length of the spring

  Model blade bearing the reference (n) between the central recess point to the point of support of the force P.

  By posing E.J.'1 "= M (x), relation in the-

  which M = moment of flexion, E = modulus of elasticity, J = moment of inertia of the surface (constant), m = local bending, we obtain for the first zone a), that is to say 0 sx Sla (n), the following equations: (I) Eji "= P (lb (n) - X) - U (La (n) - X) X2 x2 (II) EJ ' = P. (lb () X- -) U. (l1. (N) .X- -) + C

2 2

X2 X3 X2 X3

  (III) E.J.n '= P. (lb (n) .-) - U. (1 (n). - - -) + Cl.X + C2

2 6 2 6

  For the second zone b) 1a x lb (n) we obtain the following equations: (IV) EJ = P (lb (n) - X) X2 (V) EJ = P (lb (n) .X- - ) + C3

X2 X3

  (VI) E.J.T = P - (lb (n) .-) + C3 X + C4

2 6

  Constants C1, C2, C3, C4 derive from the following four boundary conditions, namely 1. X = o> m = o (no buckling) 2. X = o -> a '= o (horizontal tangent, no slope ) 3 year - () = b 3. X = la (n) -> t (a) = t (b) (point of application of force U) 4. X = la (n) -> T ( a) = "'(b) (at the point of application of the force U, common tangent and

same slope).

  The following equations are obtained for the elastic line of the beam sketched in Figure 1: x2 X2 (VII) E.J.q = P. - (3.lb (n) - X) -U. - (3. 1a (n) -X) - (VIII) E.J., n = P. - (3 lb (n,) - X) -U -. (3.X-1, ()

6 6

  X 1a X22a (n) (VIII) JJ.1 = P - (3.Ib (n) -X) -U. - (3.X-i, (yn))

6 6

the sx <lb-

  In order to use the material optimally, it is further assumed that the force U is equal to the force

  P because the tension and the moment of buckling are con-

  in area a, that is, X <la.

  The model leaf spring, following the tail-

  the, bearing the index (n + 1) to be determined by the calculation, must satisfy the following conditions according to the definition given previously (see figure 2): 1. this leaf spring must have at point X = lb ( n) = the (n +, l), the same buckling as the model leaf spring

  previous reference (n).

  2. Between the point x = o and the fulcrum (with

  plication of the force U = P) by the leaf spring mod-

  the (n) preceding, it is necessary that the spring-leaf model (n + 1) following, presents the same marginal tension - that the spring-blade model (n) already known, on the

length la (n) -

  Equations (VII) and (VIII) for the lines

  elastics also apply to the model leaf spring

  the next (n + l) simply by changing the length and

  taking another blade thickness h (+1).

  The condition of contact is reflected in the

  following equation (IX): i P Lb (n) '(lb (n + 1) - lb (n) = E.h3 2 (n + 1)

3 2

  [P.Ib (n) pIa () (n) (3 (3.1 b (n) -la (n ") eH3 6.6.b (n + 1) -Ib (n + 1) 6 (n ) With the condition of the same marginal tension one obtains another equation (X) to satisfy: P. (lb (n + 1) - lb (n)) P. (lb (n) - la (n)

2 2

h (n + 1) h (n)

  In equations (IX) and (X) we have already used

  the formulas of the surface moment of inertia J and

  of the moment resistant W of the rectangular section sup-

  placed leaf springs with j = b.h3 / 12 and w =

  b.h2 / 6, where b is the width and h is the thickness.

  These two equations (IX) and (X) can be

  Weld according to the unknowns, that is to say the length lb (n + 1) and the thickness h (n + 1) of the following leaf spring (n + 1). We obtain the equations: (XI) 3.1b (n). (lb (n) - la (n)) h (n + 1) = h (n) 2

3 2 2

  (2.Ib (n) - 3.la (n), lb (n) + la (n)) (XII)

  lb (n + 1) lb (n) + h (n + 1) (lb (n) la (n)).

  h2 h (n) Starting from a first leaf spring model n, whose dimensions, that is to say the length lb (n), t the width b and the thickness h (n) are freely chosen, and whose length 1a is equal to zero, from the

  equations (XI) and (XII) the modulus leaf spring is calculated

  order dela (n + l) directly following. To avoid misinterpretation, each model leaf spring whose dimensions were thus calculated according to equations (XI) and (XII) is used for the calculation of the following model leaf spring constituting the base leaf spring and of which the dimensions carry the index (n)

in the equations.

  It should also be noted that

  in this way, the result lb (n + 1) does not

  responds each time to half the length of the model leaf spring; the actual length is double

of the length lb (n + 1).

  Starting from the calculation described above,

  to the package of leaf springs, models, ideal, one

  gets the n model leaf springs whose dimensions

  are not used directly in manufacturing

the package of leaf springs.

  This is why each leaf spring of a

  quet of leaf springs to manufacture and which must have a

  total spring coefficient C2 determined and is

  only be made of leaf spring n = .... i made

  in the same material having the same modulus of elasticity

  from the lengths, widths or thicknesses

  determined from the longest leaf spring to be manufactured, the dimensions are calculated from their order n in the package of leaf springs of the same model. This way

  to proceed will be described in more detail below.

after.

  Starting from a leaf spring model n, predetermined

  undermined by the calculation, the dimensions of which will

  after the index 1, we obtain for the leaf spring n

  whose dimensions must be determined and whose di-

  mensions are index 2, the report of the module of

  E = E1 / E2 elasticity, the ratio of the lengths of

  L = 11/12, the ratio of the thicknesses of the leaf springs H = hl / h2, the ratio of the widths of the

  springs B = bl / b2 and the ratio of coefficients

Springs C = C1 / C2.

  According to the calculation of the first spring coefficient of a beam embedded in one end, one obtains according to the formula

C = E * H3-.B / L3

  with transformation according to the desired size and corresponding substitution of the already known quantities E1, hi, 1l, bl, C1, the springblade such that E2, C2, 12,

  b2 or h2 for the leaf spring of order n with the dimensions

  ideal ideas. Starting from this calculation corresponding to

  longer blade springs to make we have the reports

  E, L, B, H which remain constant and which apply

  for each other leaf spring n in the package of

leaf springs to manufacture.

  On the basis of the quantities thus obtained

  can realize the leaf springs. In the case of a

  direct injection according to such dimensions, we have a

  regular and optimal use of the material. In general

  the values determined, in particular the thicknesses

  do not correspond to semi-manufactured products on the market. In such cases, it is necessary to round

  up or down the calculated dimensions according to

  practical quantities. Such models

  Calculations should be as small as possible because only in this way is it possible to reach at least a very large

  optimal use of the material.

REV E N D I C A T I ONS

  1 ') Method of manufacturing a package of

  leaf springs comprising a number of

  blade spears arranged in a staggered manner and pressed against each other in their middle, a package of leaf springs whose two ends of the longest leaf spring rest against an object to be suspended

  such as a motor vehicle, a process

  characterized in that to realize a package of res-

  spells-blades that must have a certain global coefficient

  spring ball (C2) and - a number of leaf springs (n = 1 ... i) made of the same material having the same modulus of elasticity, a package is first calculated

  of model leaf springs with the same number of

  blade spells (n = 1 ... i) and the model leaf springs used as templates for sizing leaf springs of the package of leaf springs to be produced, this calculation being made taking into account the following assumptions, namely: a) all model leaf springs are made of the same material with the same modulus of elasticity, b) model leaf springs touch each other each time

  at their point of support and in the central area

  (c) the thickness of a model leaf spring is the same throughout the effective length, d) all model leaf springs have the same width throughout the effective length, e) the tension is the even in all leaf springs

  between the points of support when a force is inducing

  in the package of leaf springs, and in that each leaf spring to be manufactured is calculated from the predetermined length (12), width (b2) or thickness (h2) of the leaf spring on longer to manufacture for the dimensions, starting from the order of numbering of the similar model leaf spring in the package, and starting from this model springblade (index 1) and the leaf spring to be manufactured (index 2) on i1

  determines the ratio L = - of the lengths of the res-

12

  blade-widths B = bj / b2 of the width of the leaf springs, the ratio H = hl / h2 of the thickness of the leaf springs, the ratio E = E1 / E2 of the modulus of elasticity and the ratio

  C = C1 / C2 of the spring coefficients as well as by cal-

ass according to the formula

C = E-.H3-B / L3

  with transformation according to the desired sizes and corresponding substitution of the quantities already known

  h1, 11, b1, cl, E1 of the model leaf spring and the large

  predetermined quantities C2, E2, 12 and b2 or h2 for

  missing dimensions b2 or h2 of the leaf spring to manufacture

  quer, and based on the relationships thus determined,

  each other leaf spring and on the basis of these

  values, the packages of leaf springs

read.

  2e) Method according to claim 1, characterized

  characterized in that each model leaf spring is calculated according to the formulas of the elastic line of a beam

  recessed on one side, the free end of which

  tance lb (n) is subjected to a force P and which, at the dis-

  the (n) is subjected to a force U of opposite direction to

  that of the previous force, apply the

  the following ones: x2 X2 (VII) E.J.1 = P. - (3.lb (n) - X) -U. - (3.-1a (n) -X)

6 6

X <1

X2 2

  X lla (n) (VIII) E.J.n = P. - (3.b (n) -X) -U. -. (3.X-l (n))

6 6

* 1aS X s lb.

-

  3) Process according to claim 2, characterized

  characterized in that the model leaf spring of the following dimensions corresponding to the index (n + 1) satisfies the following conditions, namely: 1. at the location X = lb (n) = la (n +) it must have the same buckling as the model-calculated leaf spring -previously and corresponding to the index (n),

  2. between the embedding point and the point of

  by the previously calculated model leaf spring (n), the model (n + 1) leaf spring must have the same maximum marginal voltage as the leaf spring (n) , and in that the force P is equal to the force U and thus the tension and the moment of buckling are constant in

zone a, that is to say XSla.

  4 ") Method according to claims 2 and 3,

  characterized in that the equations (VII) and (VIII) of the elastic lines (only for other lengths and other thicknesses of blades h (n +)) as well as for

  the leaf spring, model, of order (n + 1) according to

  quent and the conditions of contact give the following equation: (Ix) 1 P. Lb (n) E.h3 2 (lb (n + A) - lb (n) = E.h3 2 (n + 1)

3 2

  1 P ib (n) P la (n) P1) (3.1b (n + 1) -1b (n + 1)) - (3b (n) -la (n))] 6 (n) and the condition of identical marginal constraints gives the following equation: (X) P. (lb (n + 1) - lb (n)) P. (lb (n) - la (n)

2 2

h (n + l) h (n)

  equations in which the formula of the model is used.

  of surface inertia J = b.h3 / 12 and the moment

  where W = b.h2 / 6 corresponding to the rectangular section

supposedly of the leaf springs.

  5 ') Process according to claim 4, characterized

  in that the equations (IX) and (X) are solved according to the two unknowns, namely, the length lb (n + 1) and the thickness h (n + 1) of the following model spring in the searches (n + l) by the following equations:

(XI)

  3. lb (n). (lb (n) - la (n)) h (n + 1) = h (n)

3 2 2

(2.lb (n) - 3.la () lb (n) + la (n))

(XII)

  lb (n + 1) lb (n) + h +,) (lb (n) la (n)) h (n)