CA1276478C - Method for providing a cylindrical member with increased resistance to torsional stresses and a cylindrical member constructed in accordance with said method - Google Patents
Method for providing a cylindrical member with increased resistance to torsional stresses and a cylindrical member constructed in accordance with said methodInfo
- Publication number
- CA1276478C CA1276478C CA000522641A CA522641A CA1276478C CA 1276478 C CA1276478 C CA 1276478C CA 000522641 A CA000522641 A CA 000522641A CA 522641 A CA522641 A CA 522641A CA 1276478 C CA1276478 C CA 1276478C
- Authority
- CA
- Canada
- Prior art keywords
- cylindrical member
- winding
- strip
- torque
- windings
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C3/00—Shafts; Axles; Cranks; Eccentrics
- F16C3/02—Shafts; Axles
- F16C3/026—Shafts made of fibre reinforced resin
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C53/00—Shaping by bending, folding, twisting, straightening or flattening; Apparatus therefor
- B29C53/56—Winding and joining, e.g. winding spirally
- B29C53/58—Winding and joining, e.g. winding spirally helically
- B29C53/581—Winding and joining, e.g. winding spirally helically using sheets or strips consisting principally of plastics material
- B29C53/582—Winding and joining, e.g. winding spirally helically using sheets or strips consisting principally of plastics material comprising reinforcements, e.g. wires, threads
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C53/00—Shaping by bending, folding, twisting, straightening or flattening; Apparatus therefor
- B29C53/80—Component parts, details or accessories; Auxiliary operations
- B29C53/8008—Component parts, details or accessories; Auxiliary operations specially adapted for winding and joining
- B29C53/8016—Storing, feeding or applying winding materials, e.g. reels, thread guides, tensioners
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Ocean & Marine Engineering (AREA)
- Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A cylindrical member (1) such as a trans-mission shaft is provided with high strength in torsion and light weight by means of a composite strip (2) wound helically around the cylindrical member under tension and in opposite directions (F1, F2) in succession. The tension exerted on the strip is such that a winding (2a, 2c) formed in one direction (F1) exerts on the cylindrical member a torque which is equal and of opposite direction to the torque exerted by the winding (2b, 2d) formed in the opposite direction (F2). The sum of these torques is at least equal to the maximum design torque to be exerted on the cylindrical member (1), thereby ensuring that the windings acting in opposition to the applied torque are never in compression and that the cylindrical member is under zero torsional stress.
A cylindrical member (1) such as a trans-mission shaft is provided with high strength in torsion and light weight by means of a composite strip (2) wound helically around the cylindrical member under tension and in opposite directions (F1, F2) in succession. The tension exerted on the strip is such that a winding (2a, 2c) formed in one direction (F1) exerts on the cylindrical member a torque which is equal and of opposite direction to the torque exerted by the winding (2b, 2d) formed in the opposite direction (F2). The sum of these torques is at least equal to the maximum design torque to be exerted on the cylindrical member (1), thereby ensuring that the windings acting in opposition to the applied torque are never in compression and that the cylindrical member is under zero torsional stress.
Description
~ ~7~
A ~ETH~D FOR PROVIDING A CY~INDRICAL MEM~ER WITH
INCREASED RESISTANCE TO TORSIONAL ST~ESSES AND A
CYLINDRICAL MEMBER CONSTRUCTED IN ACCORDANCE
WITH SAID METHOD
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to a method for reinforcing a cylindrical memher such as a transmission shaft which is intended to be subjected to a torque.
The invention is also directed to a cylindrical member which is endowed with increased torsional strength and which can be constructed in accordance with the method aforesaid.
Description of the Prior Art A typieal transmission shaft is constituted by a solid or hollow cylindrical member such as a metal tube (usually of steel) whieh is subjeeted to torque under serviee conditions. The torque in turn produces shearing stresses in the eylindrieal member.
Depending on the eharaeteristies of the material constituting the eylindrical member and on the value of torque, the member is subjected to a rotational displacement through a torsional angle of greater or lesser value.
In order to endow the transmission shaft with resistance to shearing stresses while assuming a limited ~ i27~78 torsional angle under the action of the maximum torque to be exerted on the cylindrical member, the thickness and diameter of said member must be of sufficient value.
In consequence, when said cylindrical member is coupled to a motor having high maximum torque, the member is relatively heavy and cumbersome.
Moreover, as the weight of a transmission shaft is greater, so it becomes more essential to devote greater care and accuracy to dynamic balancing of the shaft in order to guard against vibrations. It may prove necessary in addition to provide intermediate bearings for this purpose.
For these reasons, it is a desirable objective to minimize the weight of transmission shafts without, however, reducing their torsional strength and torque-transmitting capacity.
The precise aim of the present invention is to accomplish this objective by providing a method for re-inforcing a cylindrical member such as a transmission shaft which is intended to be subjected to a torque while limiting its diameter and/or its weight as well as the torsional angle.
SUMMARY OF THE INVENTION
In accordance with the method of the present invention, a composite small-section strip is wound helically around the cylindrical member aforesaid under 9, 2 ~478 a pre~etermined tension so as to form in a predetermined direction a first helical winding which completely sur-rounds the cylindrical member. A second winding is then formed in the opposite direction so as to pass symmetric~
ally across the first winding, whereupon the direction of winding is again reversed in order to obtain a third winding having the same direction which is parallel to the first winding, and so on in sequence. The operation is continued until the entire surface of the cylindrical member is covered by a whole number of windings in one direction, said whole number being equal to the number of windings in the opposite direction. The tension exerted on the strip is such that a winding formed in one direction exerts on the cylindrical member a low torque which is equal and of opposite direction to the torque exerted by the winding formed in the other direction.
The sum of these torques is at least equal to the maximum torque to be exerted on the cylindrical member in order to ensure that the windings acting in opposition to the torque are never in compression and that the permissible stress in the strip is not exceeded.
The torque exerted by the strip windings formed in one direction consequently balances the torque exerted by the strip windings formed in the opposite direction, with the result that the cylindrical supporting member is subjected to zero torsion.
7~i~iL7~3 When a torque is applied to the cylindrical member, tensile stresses induced by the torque in the windings formed in the same direction as said torque prevent twisting of the cylindrical member whereas, in the windings formed in the opposite direction, this torque produces a reduction in tension, the difference between the two being equal to the applied torque.
The effect thereby achieved is to limit the torsional angle of said cylindrical member. It is thus possible to reduce the diameter of said cylindrical member or its thickness in the case of a tubular member in order to make it lighter in weight.
In an advantageous embodiment of the invention, the angle at which the strip is wound on the cylindrical member is reversed each time there is a change from winding in one direction to winding in an opposite direction in order to ensure that the turns in one direction of winding pass across the turns in the other direction symmetrically with respect to a generator-line of the cylindrical msmber.
Moreover, by reason of the tension appliedto the strip during the winding operation, each turn of strip exerts on the cylindrical member a circumferential stress and a longitudinal stress which increases with each successive turn. On the other hand, the torsional stress induced by winding is constant and becomes zero ~7~78 when the winding operation stops by reason of the equilibrium between the opposite windings which are in equal number. The resultant of these stresses gives rise to a circu~lferential compression and to an axial com-pression which do not produce any torsional stress inthe cylindrical member. These compressions are not modified at the time of application of a torque of lower value than the maximum design torque since an increase in tension in one direction is compensated by a reduction by the same value in the other direction.
Preferably, the angle at which the strip is wound around the cylindrical member is equal to plus or minus 45 with respect to the axis of the tube.
This angle is of optimum value when the cylindrical member is intended to withstand torsional stresses alone. However, said angle may be smaller or larger than 45 in cases where the tube is also intended to withstand bending stresses or an internal pressure in addition to the torsional stresses.
According to another aspect of the invention, the cylindrical member such as a tran~mission shaft which is intended to be subjected to a torque as constructed in accordance with the method of the invention is re-inforced by windings of a strip consisting of continuous fibers embedded in a resin and e~tending in the direction of the strip.
~.~7~7~3 By way of example, the strip under consider~
ation is fabricated in accordance with the method described in French patent N 2,51~,441.
A strip of this type is remarkable both for its great flexibility, its low specific gravity, its high breaking strength and its high modulus of elasticity, with the result that the strip is particularly well-suited for the present application.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 iS a fragmentary plan view which shows a cylindrical member constituting a transmission shaft and illustrates the practical application of the method in accordance with the invention.
FIG. 2 is a developed view of the cylindrical member in the plane of the figure and showing on the left the stress equilihrium with zero torque and on the right the state of stresses under the action of a torque.
DETAILED DESCRIPTION OF TIIE INVENTION
FIG. 1 illustrates the method in accordance with the invention for reinforcing a cylindrical member 1 which may be a tubular member of metal and is intended to be subjected to a torque. By way of example, this cylindrical member 1 can be a transmission shaft for an automotive vehicle.
In accordance with this method, a strip 2 i5 wound completPly around said cylindrical memher 1 under ~.zt76~7~
a predetermined tension and in a predetermined direction F1 so as to form a first helical winding 2a.
A second windin~ 2b is then formed in the opposite direction F2 so as to pass across the first winding.
The direction of winding is then reversed in order to obtain a winding 2c which is in juxtaposed relation with the first winding 2a or separated from this latter by a spatial interval equal to a whole number of strips.
The direction of windiny is again reversed in order to obtain a winding 2d which is in juxtaposed relation with the second winding 2b or separated from this latter by a spatial interval equal to a whole number of strips.
The operation is thus continued until the entire surface of the cylindrical member is covered by a number of lS windings in a direction F1 equal to the number of windings in the opposite direction F2.
In order to carry out the aforementioned winding operations, the cylindrical member 1 is rotated about its axis X-X' and the strip 2 is displaced lateral-ly by making use of means known per se in a directionparallel to the axis of the cylindrical member 1 (as shown by the arrow F in FIG. 1).
The tension exerted on the strip 2 is such that the windings 2a, 2c formed in the direction of the arrows Fl exert on the cylindrical member 1 a torque which is equal and of opposite direction to the torque 69~8 exerted by the windings 2b, 2d which are formed in the other direction F2 and which is calculated so that the sum of said torques is at least equal to the maximum design torque to be exerted on the cylindrical member 1.
In order to satisfy this condition, the number of windings which have a given direction such as F1 must clearly be equal to the number of windings which have a reverse direction such as F2.
As will be readily apparent, it is necessary to ensure that the cylindrical member l affords resistance to the circumferential and longitudinal com-pressive stresses induced by the windings under tension of the strip 2 without exceeding its permissible stress.
Similarly, the tension exerted on the strip 2 must be lower than its maximum permissible stress with a view to ensuring that said strip 2 is capable of accepting the additional tensile stress produced at the time of application of the maximum torque on the cylin-drical member 1 without exceeding the value of permissible stress.
It is apparent from FIG. l that the angle a at which the strip is wound on the cylindrical member 1 is reversed each time a winding 2a, 2c in the direction F
changes over to a winding 2b, 2d in the opposite direction F2, thereby ensuring that the windings of the strips in one direction pass across the windings '7~
in the opposite dir~ction and symmetrically with respect to a generator-line of the c~lindrical member.
In the example illustrated in FIGS. 1 and 2, the angle a at which the strip 2 is wound on the cylin-drical member 1 is equal to plus or minus 45, thisangle being considered as an optimum value within the scope of the application considered ln the present invention.
The nature of the strips, the number of layers of windings and their total thickness are defined as a function of the torque to be applied to the cylindrical member 1. These values may be readily calculated from the known mechanical characteristics of the strip and in particular its elastic limit as well as those of the cylindrical member.
It is understood that the strip windings are attached at least to the ends of the cylindrical member 1. This attachment can be carried out by mechanical clamping, welding or bonding according to the nature of the material which forms the strip 2.
Said strip 2 is preferably made from continu-ous fibers. Non-limitative examples include glass, carbon, aramide fibers embedded in a thermoplastic resin such as a polyamide resin. Said strip 2 is preferably obtained in accordance with the method described in ~rench patent N 2,516,441 cited earlier.
~.~76471~
The attachment of a fiber-resin composite strip to the ends of the cylindrical member 1 or to the entire surface of this latter can readily be performed by thermoplastic welding, that is to say by heating the composite strip during winding on the cylindrical member l to a sufficient temperature to obtain surface melting of the strip surface which is intended to be applied on the cylindrical member l, this member having previously been coated in the hot state with the same thermoplastic resin. This technology is described in French patent N 2,491,044.
Referring now to FIG. 2, the technical effects and advantages of the method in accordance with the invention and of the reinforced cylindrical member obtained by this method will now be explained.
The developed view in the plane of this figure illustrates a steel tube 1 having a diameter equal to D and a circumference equal to ~D.
The successive windings of the strip 2 have been carried out with an angle a equal to plus 45, for example in the case of the odd-numbered layers 2' (shown in dashed lines in FIG. 2),and equal to minus 45 in the case of the even-numbered layers 2 (shown in full lines in the figure).
It will be assumed that the strips 2 and 2' have been wound on the cylindrical tube 1 under a ~.Z~76~L~8 tension such that the resultant stress T in the strip is equal to 2/3 of the maximum permissible stress S in said strip : T = 2S/3.
The thickness of the windings is calculated so as to afford resistance to the torque Mt with a stress equal to S. When the torque Mt is applied to the tube 1, an additional stress equal to Tj2 is developed in the strips 2 and a stress reduction equal to T/2 is produced in the strips 2'. The difference in stress between the windings 2 and 2' is therefore equal to 3T/2 - T/2 = T corresponding to a torque having a value Mt which acts in opposition to the applied torque and balances this latter.
The stress in the winding 2 is accordingly equal to 3/2 x 2S/3 = S, which is the permissible stress in the strip.
In FIG. 2, it is observed that the longitudinal and circumferential components of T in each winding, namely sl/2 and sc/2,give rise in both situations to a longitudinal compression equal to sl and to a radial compression equal to sc.
These stresses in the cylindrical member permit dimensioning of this latter in accordance with conventional rules established in strength of materials analysis. Furthermore, the fact of obtaining torsional prestress by means of a succession of multiple small-l Z76~7~3 section windings which balance each other in pairs permits the use of a cylindrical member having low torsional resistance and therefore of lightweight con-struction.
If the windings had been formed under zero tension, the stress produced in one of the windings under the action of a torque Mt would have been equal to T, thus producing a torsional angle having double the value obtained in the case of windings formed under tension in accordance with the invention and the wind-ings of opposite direction would have been in compression, thus entailing the risk of flexural deformation or buckling of the fibers.
In consequence, by utilizing the method in accordance with the invention, it is possible to reduce the torsional angle of the tube 1 by one-half the angle which would have been required for windings performed under zero tension.
The cylindrical member which is thus reinforced in accordance with the invention therefore exhibits a behavior which is totally different from that of a conventional shaft of metal or of composite materials since the applied torque is absorbed by a differential tractive force in the composite windings and longi-tudinal and circumferential compressive forces in thecylindrical supporting member with a reduced torsional stress arising from a torsional angle having a value of l.Z769~7~
one-half and a high value of tensile modulus of the composite winding compared with that of the torsional modulus of the cylindrical member.
The possibility of reducing the torsional angle of a transmission shaft offers a very significant advantage in certain applications such as load-handling robots.
Furthermore, the invention makes it possible in respect of a given maximum torque to reduce the dia-meter and especially the weight of a transmission shàftas shown by the numerical example given below.
For the transmission of a torque having a value of 400 mN, it is necessary to make use of a steel tube having a breaking strellgth of 800 MPa, an external lS diameter of 29 mm and an internal diameter of 23 mm, namely a thickness of 3 mm and weighing 1923 g per meter in length.
In accordance with the method of the preaent invention, the same torque of 400 mN can be transmitted by a steel tube of identical strength having an external diameter equal to 27 mm and an internal diameter equal to 25 mm, namely a thickness of 1 mm covered by a winding equal in thickness to l.S mm and formed by means of a strip of Kevla~ fibers embedded in a polyamide resin, the total weight of tube and winding being 830 q per meter in length.
*Trade Mark ~.~7~
The fact of being able to reduce the weight and/or the diameter of the transmission shaft makes it possible not only to produce a relatively lightweight vehicle or installation equipped with a transmission shaft of this type and thus to increase performances but also to reduce the difficulties presented by the need to obtain perfect dynamic balance of a transmission shaft of large diameter which rotates at high speed~
thus often making it possible to suppress one or a number of intermediate bearings.
A ~ETH~D FOR PROVIDING A CY~INDRICAL MEM~ER WITH
INCREASED RESISTANCE TO TORSIONAL ST~ESSES AND A
CYLINDRICAL MEMBER CONSTRUCTED IN ACCORDANCE
WITH SAID METHOD
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to a method for reinforcing a cylindrical memher such as a transmission shaft which is intended to be subjected to a torque.
The invention is also directed to a cylindrical member which is endowed with increased torsional strength and which can be constructed in accordance with the method aforesaid.
Description of the Prior Art A typieal transmission shaft is constituted by a solid or hollow cylindrical member such as a metal tube (usually of steel) whieh is subjeeted to torque under serviee conditions. The torque in turn produces shearing stresses in the eylindrieal member.
Depending on the eharaeteristies of the material constituting the eylindrical member and on the value of torque, the member is subjected to a rotational displacement through a torsional angle of greater or lesser value.
In order to endow the transmission shaft with resistance to shearing stresses while assuming a limited ~ i27~78 torsional angle under the action of the maximum torque to be exerted on the cylindrical member, the thickness and diameter of said member must be of sufficient value.
In consequence, when said cylindrical member is coupled to a motor having high maximum torque, the member is relatively heavy and cumbersome.
Moreover, as the weight of a transmission shaft is greater, so it becomes more essential to devote greater care and accuracy to dynamic balancing of the shaft in order to guard against vibrations. It may prove necessary in addition to provide intermediate bearings for this purpose.
For these reasons, it is a desirable objective to minimize the weight of transmission shafts without, however, reducing their torsional strength and torque-transmitting capacity.
The precise aim of the present invention is to accomplish this objective by providing a method for re-inforcing a cylindrical member such as a transmission shaft which is intended to be subjected to a torque while limiting its diameter and/or its weight as well as the torsional angle.
SUMMARY OF THE INVENTION
In accordance with the method of the present invention, a composite small-section strip is wound helically around the cylindrical member aforesaid under 9, 2 ~478 a pre~etermined tension so as to form in a predetermined direction a first helical winding which completely sur-rounds the cylindrical member. A second winding is then formed in the opposite direction so as to pass symmetric~
ally across the first winding, whereupon the direction of winding is again reversed in order to obtain a third winding having the same direction which is parallel to the first winding, and so on in sequence. The operation is continued until the entire surface of the cylindrical member is covered by a whole number of windings in one direction, said whole number being equal to the number of windings in the opposite direction. The tension exerted on the strip is such that a winding formed in one direction exerts on the cylindrical member a low torque which is equal and of opposite direction to the torque exerted by the winding formed in the other direction.
The sum of these torques is at least equal to the maximum torque to be exerted on the cylindrical member in order to ensure that the windings acting in opposition to the torque are never in compression and that the permissible stress in the strip is not exceeded.
The torque exerted by the strip windings formed in one direction consequently balances the torque exerted by the strip windings formed in the opposite direction, with the result that the cylindrical supporting member is subjected to zero torsion.
7~i~iL7~3 When a torque is applied to the cylindrical member, tensile stresses induced by the torque in the windings formed in the same direction as said torque prevent twisting of the cylindrical member whereas, in the windings formed in the opposite direction, this torque produces a reduction in tension, the difference between the two being equal to the applied torque.
The effect thereby achieved is to limit the torsional angle of said cylindrical member. It is thus possible to reduce the diameter of said cylindrical member or its thickness in the case of a tubular member in order to make it lighter in weight.
In an advantageous embodiment of the invention, the angle at which the strip is wound on the cylindrical member is reversed each time there is a change from winding in one direction to winding in an opposite direction in order to ensure that the turns in one direction of winding pass across the turns in the other direction symmetrically with respect to a generator-line of the cylindrical msmber.
Moreover, by reason of the tension appliedto the strip during the winding operation, each turn of strip exerts on the cylindrical member a circumferential stress and a longitudinal stress which increases with each successive turn. On the other hand, the torsional stress induced by winding is constant and becomes zero ~7~78 when the winding operation stops by reason of the equilibrium between the opposite windings which are in equal number. The resultant of these stresses gives rise to a circu~lferential compression and to an axial com-pression which do not produce any torsional stress inthe cylindrical member. These compressions are not modified at the time of application of a torque of lower value than the maximum design torque since an increase in tension in one direction is compensated by a reduction by the same value in the other direction.
Preferably, the angle at which the strip is wound around the cylindrical member is equal to plus or minus 45 with respect to the axis of the tube.
This angle is of optimum value when the cylindrical member is intended to withstand torsional stresses alone. However, said angle may be smaller or larger than 45 in cases where the tube is also intended to withstand bending stresses or an internal pressure in addition to the torsional stresses.
According to another aspect of the invention, the cylindrical member such as a tran~mission shaft which is intended to be subjected to a torque as constructed in accordance with the method of the invention is re-inforced by windings of a strip consisting of continuous fibers embedded in a resin and e~tending in the direction of the strip.
~.~7~7~3 By way of example, the strip under consider~
ation is fabricated in accordance with the method described in French patent N 2,51~,441.
A strip of this type is remarkable both for its great flexibility, its low specific gravity, its high breaking strength and its high modulus of elasticity, with the result that the strip is particularly well-suited for the present application.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 iS a fragmentary plan view which shows a cylindrical member constituting a transmission shaft and illustrates the practical application of the method in accordance with the invention.
FIG. 2 is a developed view of the cylindrical member in the plane of the figure and showing on the left the stress equilihrium with zero torque and on the right the state of stresses under the action of a torque.
DETAILED DESCRIPTION OF TIIE INVENTION
FIG. 1 illustrates the method in accordance with the invention for reinforcing a cylindrical member 1 which may be a tubular member of metal and is intended to be subjected to a torque. By way of example, this cylindrical member 1 can be a transmission shaft for an automotive vehicle.
In accordance with this method, a strip 2 i5 wound completPly around said cylindrical memher 1 under ~.zt76~7~
a predetermined tension and in a predetermined direction F1 so as to form a first helical winding 2a.
A second windin~ 2b is then formed in the opposite direction F2 so as to pass across the first winding.
The direction of winding is then reversed in order to obtain a winding 2c which is in juxtaposed relation with the first winding 2a or separated from this latter by a spatial interval equal to a whole number of strips.
The direction of windiny is again reversed in order to obtain a winding 2d which is in juxtaposed relation with the second winding 2b or separated from this latter by a spatial interval equal to a whole number of strips.
The operation is thus continued until the entire surface of the cylindrical member is covered by a number of lS windings in a direction F1 equal to the number of windings in the opposite direction F2.
In order to carry out the aforementioned winding operations, the cylindrical member 1 is rotated about its axis X-X' and the strip 2 is displaced lateral-ly by making use of means known per se in a directionparallel to the axis of the cylindrical member 1 (as shown by the arrow F in FIG. 1).
The tension exerted on the strip 2 is such that the windings 2a, 2c formed in the direction of the arrows Fl exert on the cylindrical member 1 a torque which is equal and of opposite direction to the torque 69~8 exerted by the windings 2b, 2d which are formed in the other direction F2 and which is calculated so that the sum of said torques is at least equal to the maximum design torque to be exerted on the cylindrical member 1.
In order to satisfy this condition, the number of windings which have a given direction such as F1 must clearly be equal to the number of windings which have a reverse direction such as F2.
As will be readily apparent, it is necessary to ensure that the cylindrical member l affords resistance to the circumferential and longitudinal com-pressive stresses induced by the windings under tension of the strip 2 without exceeding its permissible stress.
Similarly, the tension exerted on the strip 2 must be lower than its maximum permissible stress with a view to ensuring that said strip 2 is capable of accepting the additional tensile stress produced at the time of application of the maximum torque on the cylin-drical member 1 without exceeding the value of permissible stress.
It is apparent from FIG. l that the angle a at which the strip is wound on the cylindrical member 1 is reversed each time a winding 2a, 2c in the direction F
changes over to a winding 2b, 2d in the opposite direction F2, thereby ensuring that the windings of the strips in one direction pass across the windings '7~
in the opposite dir~ction and symmetrically with respect to a generator-line of the c~lindrical member.
In the example illustrated in FIGS. 1 and 2, the angle a at which the strip 2 is wound on the cylin-drical member 1 is equal to plus or minus 45, thisangle being considered as an optimum value within the scope of the application considered ln the present invention.
The nature of the strips, the number of layers of windings and their total thickness are defined as a function of the torque to be applied to the cylindrical member 1. These values may be readily calculated from the known mechanical characteristics of the strip and in particular its elastic limit as well as those of the cylindrical member.
It is understood that the strip windings are attached at least to the ends of the cylindrical member 1. This attachment can be carried out by mechanical clamping, welding or bonding according to the nature of the material which forms the strip 2.
Said strip 2 is preferably made from continu-ous fibers. Non-limitative examples include glass, carbon, aramide fibers embedded in a thermoplastic resin such as a polyamide resin. Said strip 2 is preferably obtained in accordance with the method described in ~rench patent N 2,516,441 cited earlier.
~.~76471~
The attachment of a fiber-resin composite strip to the ends of the cylindrical member 1 or to the entire surface of this latter can readily be performed by thermoplastic welding, that is to say by heating the composite strip during winding on the cylindrical member l to a sufficient temperature to obtain surface melting of the strip surface which is intended to be applied on the cylindrical member l, this member having previously been coated in the hot state with the same thermoplastic resin. This technology is described in French patent N 2,491,044.
Referring now to FIG. 2, the technical effects and advantages of the method in accordance with the invention and of the reinforced cylindrical member obtained by this method will now be explained.
The developed view in the plane of this figure illustrates a steel tube 1 having a diameter equal to D and a circumference equal to ~D.
The successive windings of the strip 2 have been carried out with an angle a equal to plus 45, for example in the case of the odd-numbered layers 2' (shown in dashed lines in FIG. 2),and equal to minus 45 in the case of the even-numbered layers 2 (shown in full lines in the figure).
It will be assumed that the strips 2 and 2' have been wound on the cylindrical tube 1 under a ~.Z~76~L~8 tension such that the resultant stress T in the strip is equal to 2/3 of the maximum permissible stress S in said strip : T = 2S/3.
The thickness of the windings is calculated so as to afford resistance to the torque Mt with a stress equal to S. When the torque Mt is applied to the tube 1, an additional stress equal to Tj2 is developed in the strips 2 and a stress reduction equal to T/2 is produced in the strips 2'. The difference in stress between the windings 2 and 2' is therefore equal to 3T/2 - T/2 = T corresponding to a torque having a value Mt which acts in opposition to the applied torque and balances this latter.
The stress in the winding 2 is accordingly equal to 3/2 x 2S/3 = S, which is the permissible stress in the strip.
In FIG. 2, it is observed that the longitudinal and circumferential components of T in each winding, namely sl/2 and sc/2,give rise in both situations to a longitudinal compression equal to sl and to a radial compression equal to sc.
These stresses in the cylindrical member permit dimensioning of this latter in accordance with conventional rules established in strength of materials analysis. Furthermore, the fact of obtaining torsional prestress by means of a succession of multiple small-l Z76~7~3 section windings which balance each other in pairs permits the use of a cylindrical member having low torsional resistance and therefore of lightweight con-struction.
If the windings had been formed under zero tension, the stress produced in one of the windings under the action of a torque Mt would have been equal to T, thus producing a torsional angle having double the value obtained in the case of windings formed under tension in accordance with the invention and the wind-ings of opposite direction would have been in compression, thus entailing the risk of flexural deformation or buckling of the fibers.
In consequence, by utilizing the method in accordance with the invention, it is possible to reduce the torsional angle of the tube 1 by one-half the angle which would have been required for windings performed under zero tension.
The cylindrical member which is thus reinforced in accordance with the invention therefore exhibits a behavior which is totally different from that of a conventional shaft of metal or of composite materials since the applied torque is absorbed by a differential tractive force in the composite windings and longi-tudinal and circumferential compressive forces in thecylindrical supporting member with a reduced torsional stress arising from a torsional angle having a value of l.Z769~7~
one-half and a high value of tensile modulus of the composite winding compared with that of the torsional modulus of the cylindrical member.
The possibility of reducing the torsional angle of a transmission shaft offers a very significant advantage in certain applications such as load-handling robots.
Furthermore, the invention makes it possible in respect of a given maximum torque to reduce the dia-meter and especially the weight of a transmission shàftas shown by the numerical example given below.
For the transmission of a torque having a value of 400 mN, it is necessary to make use of a steel tube having a breaking strellgth of 800 MPa, an external lS diameter of 29 mm and an internal diameter of 23 mm, namely a thickness of 3 mm and weighing 1923 g per meter in length.
In accordance with the method of the preaent invention, the same torque of 400 mN can be transmitted by a steel tube of identical strength having an external diameter equal to 27 mm and an internal diameter equal to 25 mm, namely a thickness of 1 mm covered by a winding equal in thickness to l.S mm and formed by means of a strip of Kevla~ fibers embedded in a polyamide resin, the total weight of tube and winding being 830 q per meter in length.
*Trade Mark ~.~7~
The fact of being able to reduce the weight and/or the diameter of the transmission shaft makes it possible not only to produce a relatively lightweight vehicle or installation equipped with a transmission shaft of this type and thus to increase performances but also to reduce the difficulties presented by the need to obtain perfect dynamic balance of a transmission shaft of large diameter which rotates at high speed~
thus often making it possible to suppress one or a number of intermediate bearings.
Claims (8)
1. A method for providing a cylindrical member such as a transmission shaft with increased resistance to torsional stresses, wherein a composite strip is wound helically around said cylindrical member under a predetermined tension so as to form in a predetermined direction a first helical winding which completely surrounds the cylindrical member, a second winding is then formed in the opposite direction so as to pass symmetrically across the first winding, the direction of winding is then reversed in order to obtain a winding which is parallel to the first winding, whereupon the direction of winding is again reversed in order to obtain a winding which is parallel to the second winding and the operation is continued until the entire surface of the cylindrical member is covered by a double interlaced layer formed by a number of windings in one direction equal. to the number of windings in the opposite direction, the tension exerted on the strip being such that the windings formed in one direction exert on the cylindrical member a torque which is equal and of opposite direction to the torque exerted by the windings formed in the other direction so as to ensure that the winding which is in opposition to the applied torque is never in compression and that the cylindrical member is in a state of zero torsion when all the windings have been completed, the number of layers being so determined that the torque induced by the sum of said windings is at least equal to the maximum torque to be exerted on the cylindrical member without exceeding the permissible stress in the composite strip which works in tension or the permissible stress in the basic cylindrical body which works in compression.
2. A method according to claim 1, wherein the angle at which the strip is wound on the cylindrical member is reversed each time there is a changeover from a winding in one direction to a winding in an opposite direction in order to ensure that the turns in one direction of winding pass across the turns in the opposite direction symmetrically with respect to a generator-line of the cylindrical member.
3. A method according to claim 2, wherein the angle at which the strip is wound on the cylindrical member is equal in addition to plus or minus 45° with respect to the axis of the tube.
4. A method according to claim 1, wherein the tension exerted on the strip at the time of winding is calculated so as to ensure that said strip is capable of accepting the additional tensile stress produced at the time of application of maximum torque to the cylindrical member without thereby exceeding the permissible stress.
5. A method according to claim 1, wherein each winding of the strip is attached at least to the ends of the cylindrical member.
6. A method according to claim 1, wherein the composite reinforcement strip is formed of parallel and continuous fibers embedded in a matrix of thermoplastic resin.
7. A method according to claim 1, wherein the strip is attached to the cylindrical member and to itself by means of a heat-sealing operation performed at the same time as winding under tension.
8. A cylindrical member to be subjected to torque and constructed in accordance with the method according to claim 1, wherein said cylindrical member is reinforced by windings of a strip formed of continuous fibers embedded in a thermoplastic resin and extending in the direction of said strip.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8516842 | 1985-11-14 | ||
| FR8516842A FR2589962B1 (en) | 1985-11-14 | 1985-11-14 | METHOD FOR REINFORCING A CYLINDRICAL ELEMENT WITH TORSIONAL EFFORTS AND A CYLINDRICAL ELEMENT THEREFOR |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1276478C true CA1276478C (en) | 1990-11-20 |
Family
ID=9324810
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000522641A Expired - Fee Related CA1276478C (en) | 1985-11-14 | 1986-11-12 | Method for providing a cylindrical member with increased resistance to torsional stresses and a cylindrical member constructed in accordance with said method |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0222660A1 (en) |
| JP (1) | JPS62113909A (en) |
| AU (1) | AU6500686A (en) |
| CA (1) | CA1276478C (en) |
| ZA (1) | ZA868416B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE523196C2 (en) * | 2001-10-31 | 2004-03-30 | Saab Ab | Device and method of drive shaft |
| EP3382220B1 (en) * | 2017-03-31 | 2020-12-09 | Crompton Technology Group Limited | Composite structural component with tension/compression mechanical joint |
| US20220025922A1 (en) * | 2018-09-21 | 2022-01-27 | Tirsan Kardan Sanayi Ve Ticaret A.S. | Production assembly and method for hybrid composite driveshaft tube |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR337233A (en) * | 1903-12-01 | 1904-04-01 | Claude De Albertis | New rigid transmission system without torsion |
| US3553978A (en) * | 1969-10-06 | 1971-01-12 | Gen Motors Corp | Composite propeller shaft construction and method of making |
| US4331497A (en) * | 1979-08-27 | 1982-05-25 | Allied Corporation | Composite shell |
| FR2491044A1 (en) * | 1980-09-26 | 1982-04-02 | Spie Batignolles | METHOD FOR REINFORCING A HOLLOW BODY MADE BY WINDING A PROFILE, PROFILE FOR ITS IMPLEMENTATION AND PIPELINES RELATING THERETO |
| JPS59137613A (en) * | 1983-01-25 | 1984-08-07 | Mitsubishi Rayon Co Ltd | Transmission shaft made of fiber reinforced composite material |
| GB8323604D0 (en) * | 1983-09-02 | 1983-10-05 | Westland Plc | Fibre-reinforced shaft assembly |
| IT1161532B (en) * | 1983-10-26 | 1987-03-18 | Agusta Aeronaut Costr | STEEL TUBULAR TRANSMISSION SHAFT |
| EP0145810A1 (en) * | 1983-12-20 | 1985-06-26 | Joachim Dr. Schnell | Flexible shaft |
-
1986
- 1986-10-29 EP EP86402426A patent/EP0222660A1/en not_active Withdrawn
- 1986-11-04 ZA ZA868416A patent/ZA868416B/en unknown
- 1986-11-11 AU AU65006/86A patent/AU6500686A/en not_active Abandoned
- 1986-11-12 CA CA000522641A patent/CA1276478C/en not_active Expired - Fee Related
- 1986-11-13 JP JP61268762A patent/JPS62113909A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62113909A (en) | 1987-05-25 |
| ZA868416B (en) | 1987-06-24 |
| AU6500686A (en) | 1987-05-21 |
| EP0222660A1 (en) | 1987-05-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6612556B2 (en) | Multihelical composite spring | |
| US4863416A (en) | Misalignment accommodating composite shaft | |
| US4664644A (en) | Fiber reinforced plastic drive shaft and method of manufacturing thereof | |
| US6409606B1 (en) | Power transmission shaft | |
| US4391594A (en) | Flexible coupling | |
| US4589679A (en) | Safety steering column made of fiber-reinforced synthetic materials | |
| US4322062A (en) | Torsion spring damper | |
| EP0461492B1 (en) | Elastic joint | |
| US4552035A (en) | Reinforced connecting link means | |
| US6824323B2 (en) | Connecting ball joint, for example for an anti-roll bar of a running vehicle | |
| US5364061A (en) | Torque take-up link for a vehicle engine | |
| GB1582320A (en) | Felxible shaft couplings | |
| US5553964A (en) | Mechanical tubular element such as transmission shaft of a motor vehicle | |
| US3576336A (en) | Force transmitting system | |
| EP0052993A1 (en) | Improvements in and relating to load transmission members | |
| US4577736A (en) | Tubular member, especially for a safety steering column for motor vehicles | |
| CA1276478C (en) | Method for providing a cylindrical member with increased resistance to torsional stresses and a cylindrical member constructed in accordance with said method | |
| US5353649A (en) | Non-contact detecting type torque sensor | |
| US4569667A (en) | Flexible coupling | |
| US3240082A (en) | Push-pull cable with reinforced core element | |
| EP0213816B1 (en) | Composite member wound at optimized angles | |
| US4634399A (en) | Structural component for transmitting torque | |
| US4557781A (en) | Elastomeric member and method of manufacture therefor | |
| GB2070194A (en) | Resilient shaft couplings | |
| JPH03236946A (en) | Manufacturer of fiber reinforced cylinder tube |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |