FR2645930A1 - ELASTIC RING - Google Patents

Abstract

The invention relates to elastic rings. In an elastic ring comprising an elastomeric interlayer 13 interposed between rigid inner and outer elements 11, 12, the interlayer is reinforced by a sleeve 14 of the tubular type, of substantially non-rigid shape. The sleeve 14 is preferably semi-rigid and is preferably formed of a material having a flexural strength of between 600 and 2,500 kgf / cm ** 2. Main application: elastic rings to resist fatigue.

Description

This invention relates to an elastic ring

  a type which comprises an inner rigid member, an outer rigid member which surrounds and is spaced from the inner rigid member, and an intermediate layer of resilient elastomeric material which extends between the

  stiff inside and outside and assembles them.

  The invention relates in particular to an elastic ring

  of the type described above and in which the

  tercalaire elastic elastomeric material is provided with an embedded reinforcement, intended, among other things, to increase the

  radial rigidity of the ring compared to larigidi-

  radial section it would present if the intermediate layer

was not reinforced.

  The invention furthermore relates, although

  exclusively, an elastic ring with a

  drowned as described above and in

  which the elastomeric material is precompressed radially

  is lying. In a known form of elastic ring of this

  type, the embedded reinforcement is equipped with a tubular

  steel wire. This insertion is arranged to divide the elastic elastomeric spacer layer into parts

  tubular radially inner and radially outer

  in the classical technique, these parts are

  both attached to the insertion by adhesion. The pre-

  radial compression of the interlayer is obtained

  by a necking of the outer rigid element to pre-

  compress the radially outer tubular part of

  the intermediate layer, and the radial tubular part

  the inner layer of the intermediate layer is then subjected to precompression by expansion of the inner rigid element, which must therefore be

tubular section shape.

  Although the ring shape described in the

  The preceding paragraph has good performance and good resistance to fatigue when used in many applications, it is affected by the disadvantage of being long and expensive to manufacture in Europe.

  because of the need to carry out two operations,

  see a narrowing operation and a scaling operation

  tation, to ensure the pre-compression of the two parts, radially inner and radially outer, of the intermediate layer of resilient elastic elastomeric material. In addition, the ring must necessarily possess

  a rigid inner tubular element and not full.

  Moreover, for certain applications, it can be seen that the fatigue strength of the elastic ring

  is not as good as one wants.

  To avoid the need to perform both shrinkage and expansion operations and also to allow the use of solid interior elements of solid section, it has already been proposed to make use of an interlayer reinforcement comprising two shells semicylindrical steel which, as in oas a reinforcement of tubular steel, are attached to the radially inner and radially outer portions of the interlayer. During the initial assembly, the adjacent longitudinal edges of the shells are arranged to be slightly spaced in the circumferential direction. Following the narrowing of the element

  the outer part of the outer layer

  tercalaire is compressed and tends to bring the adjacent edges of the shells closer to each other, to determine

  also a compression of the radially inte-

  of the intermediate layer, without this requiring

  of dilation of the inner rigid element.

  The use of a reinforcement composed of a pair of semicylindrical shells thus improves the ease of manufacture and also makes it possible to use a

  rigid element inside a massive sectional shape.

  Unfortunately, these benefits are frequently compensated

  in many applications of the product by a reduction

  resistance to fatigue. In particular, undesirable stresses may occur at the adjacent longitudinal edges of the shells, which constraints

  are concentrated in the regions of these longitudinal edges.

  and this leads to premature failure of the

  fatigue ring. There is also a risk of experiencing difficulties

  used to correctly position the shells in the molding tool. The present invention aims in its widest aspect, to achieve an improved elastic ring

  of the kind having a reinforced interlayer.

  In another of its aspects, the invention aims to achieve

  an improved elastic ring, precompressed radially

  which has the ease of manufacture of the rings

  of the type which includes reinforced shells

  the semi-cylindrical, which does not require the use of a rigid inner member of a hollow section shape and which can be designed to possess

good resistance to fatigue.

  According to the present invention, the interlayer

  elastic elastomeric material contained in a

  elastic ring is reinforced by a reinforcing layer

  tubular material made of a material that is capable of deforming in response to compressive forces

  manifest in a radially inte-

  upper or radially outer layer of the

  lar. The tubular reinforcement layer is preferably

  able to respond to compressive forces

  of this nature, which are exerted as a result of the dilation

  radially contraction or radial contraction of a respective inner or outer rigid element, causing

  radial compression of the other of said parts tu-

  radially inner and radially outer bungs

of the interlayer.

  To avoid confusion, it is stated that,

  In this memo, the term "deformation" is

  to mean a change of shape that may be a localized change of shape, as well as a change of dimension that does not necessarily involve a

shape change.

  According to the invention, the tubular reinforcing layer is of a non-metallic material, unlike

  to the steel used in the classical technique.

  Consequently, according to the invention, it is necessary to make use of a reinforcement of a tubular type in a single

  piece, as opposed to a composite set of shell-

  the, and the reinforcement must be made of a material which, unlike the high rigidity of the steel used

  classically, is substantially semi-rigid.

  The semi-rigid reinforcing material should be a material having a modulus of elasticity in the range of 5,000 to 70,000 kgf / cm 2 and, in a more preferred embodiment, in the range of 16,000 to 30,000 kgf. / cm. In this way, if a necking operation is performed on the outer rigid member, this will cause radial compression of the outer portion of the resilient elastomeric spacer layer and will also create circumferential compressive stresses in the tubular reinforcement to provide, thanks to the module

  elasticity of the reinforcement material, a compres-

  radial expansion of the radially interior part

  eure of the interlayer of elastic elastomeric material. Conversely, if you perform an operation of

  dilation on the inner rigid element, when this

  it is of a tubular form, this operation can

  be used to radially compress the radia-

  the inner layer of the intermediate layer, thereby to create circumferential stress stresses in the tubular reinforcement,

  this way a radial expansion of the tubular reinforcement

  which is sufficient to determine a compression

  desired radial of the outer part of the inner layer

  elastic elastomeric tercalaire. In general, it is expected that the radial compression of the outer rigid member will be more advantageous to perform and will have the advantage of

  make it possible to compress the

  interior of the interlayer more easily

  that the compression of the radially outer portion by expansion of the inner rigid element would be achieved. According to another aspect of the invention, it is provided that the intermediate layer of elastic elastomeric material is reinforced by a tubular reinforcing layer made of a material having a flexural strength in the range of 600 to 2500 kgf / cm2 and, preferably, flexural resistance of the gap

from 900 to 1,000 kgf / cm2.

  It is estimated that by providing a layer of reinforcement

  tubular cement made of a material having a resistance

  the flexural strength within the wide range mentioned in the preceding paragraph, the reinforcement is able to deform appropriately when the ring is the seat of a radial relative movement or a movement

  taper between the rigid inner and outer elements

  and therefore able to avoid or reduce the

  manifestation of undesirably high levels of con-

  constraint centers which normally affect

  adversely affect the fatigue strength of the ring.

  In general, materials with a resistance

  bending strength within the aforementioned wide range and, preferably within the restricted range,

  lend themselves to building a layer of

  tubular cement of a thickness which is sufficient to provide the desired reinforcing effect to stiffen the ring, in particular to withstand relative radial displacement between the inner rigid members and

  outside, but which is otherwise sufficiently com-

  squeezable and expandable in the circumferential direction

  to ensure, if desired, the transmission

  radial compression of the radially

  outer or radially outer layer of

  to the other part of the interlayer.

  According to the present invention, it is furthermore preferred that, in the use of the ring, the tubular reinforcing layer can only deform in its elastic limit. In this way, she will tend herself to

  back to its original form and configuration when

  that the ring is discharged from the forces applied from the outside. Non-metallic materials particularly well suited for forming the tubular reinforcing layer include plastics such as polyamides, nylon 6 and nylon 66, acetal, Hytrel and Delrin. The reinforcing layer may be of a textile-type construction but, in general, it

  will not have a sufficiently high flexural strength

  therefore, it is envisaged that normally the tubular reinforcement layer will be formed of a tubular layer

  of non-textile material. However, the reinforcing layer

  tubular cement may comprise embedded reinforcement.

  Thus, for example, the tubular reinforcement may comprise a nylon tubular sleeve 6 which contains an embedded reinforcement of glass fibers.

  cut, balls or spheres, or

  See. The tubular reinforcing layer can be

  provided with at least one opening in its wall. This facilitates

  lite the flow of the material radially towards the

  inside or out through the reinforcing layer

  during the molding operation which forms the parts

  radially inner and radially outer portions of the elastic elastomeric spacer layer. This is

  translated also by continuity and by solidarity

  mechanical assembly between the molded materials of said radially inner and radially outer portions of the spacer layer. The reinforcement layer is

  preferably provided with at least one circumferential series

  many openings. It is envisaged that the thickness

  of the tubular reinforcement layer should be

  only within the range of 15% to 25% of the radial spacing of opposite surfaces of the inner and outer rigid members. This is to be compared on a medium basis with the tubular or semi-cylindrical steel reinforcements used hitherto and which typically have a thickness of the range of 10% to 20% of the radial spacing of the opposite surfaces of the

  rigid elements inside and outside.

  To further facilitate the reduction or elimination of stress concentrations, each axial end portion of the reinforcing layer

  tubular is of reduced wall thickness,

  relatively to the middle part of the layer. The inner and outer surfaces of the reinforcing layer may be shaped to provide the

  end regions of a conical shape.

  An embodiment of the invention will now be described by way of example only with reference to the accompanying schematic drawings in which: FIG. 1 is a longitudinal sectional view of an elastic ring according to the present invention; FIG. end view of the elastic ring of Figure 1; Figure 3 is a longitudinal sectional view of a sleeve variant that can be used in the elastic ring of Figures 1 and 2; and FIG. 4 is an end view of the sleeve of the

figure 3.

  An elastic ring 10 of a circular cross-sectional shape comprises, as shown in FIGS. 1 and 2, inner and outer tubular rigid elements 11, 12, both formed of steel and a

  elastic elastomeric spacer layer 13 in two parts.

  made of natural rubber, which extends between opposite surfaces of the rigid elements 10, 11 and

attached to these surfaces.

  The rubber interlayer 13 is made

  forced from a tubular sleeve 14 of nylon 66 which divides the intermediate layer into radially inner and radially outer portions 16, 15 which are both attached to the sleeve 14. The sleeve 14 is formed of nylon 66 and, for most of its length, it has a thickness of 1.5 mm, which represents 23% of the distance between the opposite inner and outer surfaces of the inner and outer rigid elements are spaced radially. The axial end portions of the wall of the sleeve 14 are of a conical section; this is

  obtained by forming chamfers on the surfaces

  inside and outside of the sleeve 14, at each of its

axial ends.

  The nylon material 66 has a flexural strength of 880 kgf / cm 2 and a modulus of elasticity of 18

  000 kgf / cm. The sleeve 14 has in this case a thick

  1 mm, a length of 39 mm and a diameter

average of 24.5 mm.

  The axial length of the outer rigid element is smaller than that of the inner rigid element

  and the axial length of the sleeve is between

  the rigid elements inside and outside. The man

  chon 14 is disposed substantially halfway in the radial direction between the inner rigid members and

  outside but is slightly closer to the

  rigid interior, so that the parties concerned

  upper and outer 16, 15 of the intermediate layer

  elastic are substantially of the same volume.

  The rigid inner element is of a thickness

  relatively strong wall and is equipped, between

  end regions 17, of a circumferential recess 18 with an axial length which corresponds to the axial length

of the sleeve 14.

  After assembling the elastic ring, as

  described above, and the fixing of the surfaces

  rigid elements and the sleeve to the respective parts of the elastomeric intermediate layer 13, the

  radially outer portion 15 of the intercalated layer

  re is put in a state of precompression by a

  radial traction of the outer rigid element 12. As a result, the sleeve 14 is subjected to circumferential compression stresses and decreases in diameter, thereby effecting compression of the lower portion 16 of the elastomeric spacer layer.

  against the outer surface of the rigid element

  laughing. In an elastic ring according to one aspect of the invention, use is made of a different type of tubular reinforcing sleeve 20, as shown in FIGS. 3 and 4. The sleeve 20 is formed of nylon 66 and

  is equipped, between its ends, with two series 21,

  axially, openings 22 of circular shape.

  Each series 21 comprises four of said openings which

  are evenly spaced in the circumferential direction

  -competitive. The axial end portions of the sleeve 20 may be U-shaped in sectional view, as shown in FIG. 3, or they may be chamfered in the manner described for the sleeve 14 of FIG. The use of openwork type of sleeve

  facilitates the formation of the inner and outer parts

  16, 15 of the rubber interlayer 13 by

  a molding operation in place, in which the

  mouldable material can flow through the wall of the man-

  chon and in which, one can obtain a binding of

  mechanical appearance between the inner and outer parts

16, 15.

  It's easy to understand when reading this

  which precedes the fact of using in an elastic ring

  a reinforcing layer of the specified type which represents a significant difference

  long established in the art of manufacturing

  elastic ring design, facilitates manufacturing and provides the possibility of using tubular-type internal rigid elements without any

  significant disadvantage, such as a limitation of the resistance

  In fact, it is estimated that the use of

  reinforcement layer of the kind described in the pre-

  memory, and in accordance with the present invention,

  leads to an extremely useful improvement of the resistance

  compared to that observed in conventional rings of a known design.

long time.

  Although the invention has been described in part

  a resilient ring in which the reinforced elastomeric interlayer can be subjected to radial prestressing by expansion of

  the rigid element inside or by compression of the element

  external rigid structure, in a modified form, the

  The elastomeric material is not precompressed radially, or it is precompressed radially by others.

  means. Thus, in a modified form, we

  read a ring in the form shown in the figures

  1 to 4, but without radial precompression of the inner layer

rubber tercalaire 13.

Claims (15)

R E V E N D I C A T I ONS   1. Elastic ring comprising a rigid element   interior (11), an outer rigid element (12) which   the inner rigid member is spaced apart and spaced therefrom, and an intermediate layer (13) of elastic elastomeric material which extends between the inner and outer rigid members and which assembles them, characterized in that said intermediate layer (13) of resilient elastomeric material is reinforced by a tubular reinforcing layer made of a material which is capable of deforming in response to compressive forces which manifest themselves   in a tubular part, radially inside or   outer dial (16, 15) of the intermediate layer (13). 2. Elastic ring according to claim 1,   characterized in that the tubular reinforcing layer   (14) is made of a material which is substantially semi-rigid. 3. Elastic ring comprising a rigid element   interior (11), an outer rigid element (12) which   turns the inner rigid member and is spaced therefrom, and an intermediate layer (13) of elastic elastomeric material   which extends between the inner and outer rigid   and assembles them, characterized in that   interlayer (13) of elastic elastomeric material is reinforced by a tubular reinforcing layer (14) made of a material having a flexural strength   contained in the range of 600 to 2,500 kgf / cm2.   An elastic ring according to claim 3, characterized in that the material of said tubular reinforcing layer (14) has a resistance to   bending of the range from 900 to 1000 kgf / cm.   5. Elastic ring according to any one of   preceding claims, characterized in that the   tubular reinforcement layer (14) is a layer of non-metallic material.   6. Elastic ring according to any one of   preceding claims, characterized in that said tubular reinforcing layer (14) is capable of deforming in response to compressive forces occurring in the elastomeric material as a result of   radial expansion or radial contraction of the   rigid inside or outside (11, 12) respecti-   in order to thereby cause radial compression of the other of the radially inner or radially outer tubular parts (16, 15) of the interlayer (13).   7. Elastic ring according to claim 6, characterized in that the parts (16, 15) of the layer   interlayer of elastic elastomeric material which is   wind respectively inside and outside the   tubular reinforcement layer are in radial compression   Diale. 8. Elastic ring according to claim 7, characterized in that the outer rigid element (12) is an element which has been subjected to compression for   cause residual compression of the parts   upper and outer (16, 15) of the intermediate layer   (13) elastic elastomeric material.   9. Elastic ring according to any one of   preceding claims, characterized in that the   tubular reinforcing layer (14) is of a type which, in the normal use of the elastic ring, will tend to return to its shape and its initial configuration when the ring is relieved of the constraints. applied from the outside.   10. Elastic ring according to any of the   preceding claims, characterized in that the   tubular reinforcing layer (14) is formed from   a layer of non-textile material.   11. Elastic ring according to any one of   preceding claims, characterized in that   the radial thickness of the tubular reinforcing layer (14) is between 15% to 25% of the radial spacing of the opposite surfaces of the elements. rigid inside and outside.   An elastic ring according to claim 11, characterized in that said thickness of the tubular reinforcing layer (14) is in the range of 20% to 25% of the radial spacing of the opposite surfaces of the   rigid inner and outer elements (16, 15).   13. Elastic ring according to any one of   preceding claims, characterized in that the   tubular reinforcement layer (14) is provided with   at least one opening (22) in its wall.   14. Elastic ring according to claim 11,   characterized in that the tubular reinforcing layer   lair (14) is provided with at least one circumferential series number of openings (22).   15. Elastic ring according to any one of   preceding claims, characterized in that   at least one axial end region of the tubular reinforcing layer (14) is reduced in thickness   compared to the axially central region.