GB2190979A

GB2190979A - Coupling

Info

Publication number: GB2190979A
Application number: GB08711864A
Authority: GB
Inventors: Ludwig Maier
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-05-21
Filing date: 1987-05-20
Publication date: 1987-12-02
Also published as: AU7324987A; GB8711864D0; JPS62283218A; DE3716941A1; ZA863782B

Description

SPECIFICATION Coupling THIS invention relates to couplings and more particularly to flexible couplings. Couplings are normally used to couple a driving member to a driven member and it is generally accepted that it is extremely difficult to align the driving member up with the driven member so that there is no run-out on the coupling whatsoever. Therefore, in practice, in many cases, allowance is made for misalignment by means of flexible couplings. Many different kinds of flexible couplings are known and there are various characteristics which are desirable in flexible couplings. However, a difficulty lies in combining some or all of these characteristics efficiently in a coupling. It is accordingly an object of this invention to provide a flexible coupling which minimizes the abovementioned difficulty. According to the invention there is provided a flexible coupling which comprises an inner sleeve, having radially outwardly extending projections and an outer sleeve having radially inwardly extending projections, wherein the projections of the inner and outer sleeves are disposed between and spaced from each other; and resiliently, flexible cushion means moulded in situ between the sleeves, the areas of the inner and outer sleeves interfacing with the cushion means being pre-treated with a bonding agent prior to moulding of the cushion means, and the sleeves being adapted to be secured one to a driving member and the other to a driven member. The inner and outer sleeves may be manufactured of metal and the flexible cushion means may comprise a substantially annular elastomeric cushion disposed between the inner and outer sleeves. In the preferred form of the invention the inner sleeve is provided with spaced, toothlike projections located circumferentially on at least part of its outer surface and the outer sleeve is also provided with spaced tooth-like projections located circumferentially on at least part of its inner surface, the teeth of the inner and outer sleeves being disposed between and spaced from each other with the cushion means disposed between the teeth. The outer sleeve may be provided with a flange. A composite flexible coupling may comprise two coupling sections in the form of the above couplings, the flanges of such coupling sections being connected to each other and one of the coupling sections being adapted to be connected to a driving member and the other to a driven member. In yet another form of the invention the coupling may include two inner sleeves located within an outer sleeve, the inner sleeves being separated from one another by a resiliently flexible cushion means and the inner sleeves being adapted to be connected one to a driving member and the other to a driven member. The inner sleeves may be adapted to be secured to a shaft by a taper-bush, keying or other locking arrangement. According to yet another aspect of the invention, a method of manufacturing a coupling is provided including the step of pre-treating an inner sleeve and an outer sleeve with a bonding agent and moulding the inner sleeve to the outer sleeve by locating the outer sleeve and the inner sleeve in a die, heating the die to a suitable temperature, injecting an uncured elastomeric compound under pressure into the die and maintaining the compound under pressure and at a suitable temperature throughout a curing cycle, the compound once cured, forming a resiliently flexible cushion means between the inner and outer sleeves. The method may include the steps of pretreating the sleeves by firstly degreasing and shotblasting them and secondly by applying a bonding agent to them prior to injecting the uncured elastomeric compound. The method may include the steps of pretreating the sleeves by firstly degreasing and shotblasting them, and secondly by coating the sleeves with a bonding agent, allowing the substance to dry and thereafter applying a suitable substrate to the sleeves which will aid the bonding process and then allowing the substrate to dry, the substrate comprising a mixture of an uncured rubber compound and a solvent. Furthermore, the method may include the steps of curing the rubber compound at a pressure of between 200 kg/cm and 5000 kg/cm and at a temperature of 135[deg]C to 165.C, the material once cured having a shore hardness of 40 to 70. The invention will now be described by way of a non-limiting example with reference to the accompanying drawings in which: Figure 1 is a diagrammatic, side view of one form of a coupling according to the invention; Figure 2 is a diagrammatic, cross-sectional view on line II-II of figure 1; Figure 3 is a diagrammatic, cross-sectional view on line III-III of Figure 2; Figure 4 is a diagrammatic, side view of a composite coupling; and Figure 5 is a diagrammatic, partially sectioned, side view of another form of a coupling according to the invention. Referring to Figures 1, 2 and 3, a coupling 1 is secured to a shaft 2 by means of a key 3. The coupling includes an outer sleeve 4 and an inner sleeve 5 which are separated from one another by a resiliently flexible, cushion means 6 which is made of a suitable synthetic elastomeric compound. Toothshaped projections 7 and 8 which include par- allel sides 7a and 8a respectively and rounded crowns 7b and 8b respectively are spaced circumferentially on part of the outer surface of the inner sleeve 5 and on part of the inner surface of the outer sleeve 4 respectively. Teeth 8 are arranged so that they are disposed between and spaced from teeth 7 with the cushion means 6 disposed between the teeth. This arrangement allows for a degree of torsional, axial as well as lateral movement of the inner and outer sleeves relative to each other. Outer sleeve 4 is provided with a flange 9 which contains a number of spaced bolt holes 10. Referring now to Figure 4, a composite coupling 11 consists of two of the couplings 1, as shown in figure 1, located back-to-back. The couplings 1 are connected to each other via their flanges 9 by means of bolts 12. Composite coupling 11 connects shafts 2 and 13 together. Referring now to figure 4 in which another embodiment of the invention is shown, a coupling 14 includes an outer sleeve 15 and two inner sleeves 16. Inner sleeves 16 are separated from one another and from outer sleeve 15 by a resiliently, flexible cushion means 17. Inner sleeves 16 are provided with flanges 18. In use coupling 1 is secured by means of a taper-bush arrangement 3 to shaft 2 which forms part of a driving member [not shown]. It is possible that the coupling may be secured to the shaft 2 by a key [not shown] or any other suitable locking means. Flange 9 is secured to an adaptor plate of a driven member [not shown]. It is also possible that the connections may be made the other way round. In other words shaft 2 may be connected to the driven member and flange 9 may be connected to the driving member. It is possible that the flexible coupling may be connected to an inflexible coupling, one of the couplings being connected to a driven member and the other to a driving member. The driving member is then aligned with driven member. In practice the members may be aligned with one another without the use of a clock-gauge [not shown] and even if a clock-gauge is utilized, it will be extremely difficult to align the members perfectly. Therefore, the flexibility of the elastomeric compound is designed to accommodate a reasonable degree of parallel and angular misalignment and also end float. In use when two couplings 1 are connected back-to-back as shown in Figure 4 the amount of mis-alignment and end float which can be tolerated by the composite coupling il is increased. The amount of mis-alignment which can be tolerated by the composite coupling 11 depends on its size. It has been found that generally the coupling can tolerate 4 mm of parallel mis-alignment, 5[deg] of angular misalignment and up to 5 mm end float. The amount of torque which can be transmitted by composite coupling 11 also depends on its size. When torque is applied to coupling 1, inner sleeves 5 tends to turn relative to outer sleeves 4. Composite coupling 11 is designed to deflect about 1[deg] when 40% of the rated torque is applied to the coupling and to deflect about 2[deg] when 100% of the rated torque is applied to the coupling. Under shock-loading conditions coupling 11 is designed to deflect about 5[deg] when the rated torque of the coupling is exceeded by 300%. The maximum deflection which the coupling 1 can tolerate is in the region of 15[deg]. It is obvious that the torsional stiffness of the coupling 1 and composite coupling 11 is non-linear. This is extremely important in the case of shock-loading. The coupling should be selected according to the rated torque that will be applied to it. Under normal operating conditions when 100% of the rated torque is applied to the coupling it should not deflect significantly. This means that when a shock load is applied to the coupling it is able to accommodate the shock load by deflecting significantly. This deflection can prevent any damage occurring to the driven unit or driving member. It is clear that the bond between the metal sleeves of the coupling and the flexible cushion means must be very firm and a bonding agent is therefore applied to the sleeves prior to introducing the cushion means in order to obtain a bond which would withstand extreme working conditions such as shock loads. If no bonding agent is used the cushion would be prone to tear away from the sleeves under shock loading conditions or periods of very high torque such as the start-up torque and torque peaks during normal operation of the apparatus to which the coupling is connected. A good application for these couplings 1 and 11 is to be found in crusher drives. A crusher, which is normally driven by an electric motor, can be subject to severe shock loading when a piece of tramp metal passes through the crusher. In such a case the shock loading is more or less instantaneous, and if the coupling between the electric motor and the crusher cannot accommodate the shock, severe damage may be caused to the crusher. The bolts 12 may be designed so that they shear when an excessive load is applied to coupling 11. If a single coupling 1 is used, the bolts connecting it to an adaptor plate could also be designed to shear under excessive loads. Coupling 14 is used in low torque applications. The driven member is connected to one of the inner sleeves 16 and the driving member to the other inner sleeve 16. The members are connected to flanges 18. The couplings are produced in the following manner: The inner and outer sleeves are cast from 38/42 S.G. iron and are machined to size. The sleeves are then cleaned to remove any grease and are shot-blasted with platinum slag. A bonding agent, commonly known as chemlock 252 is applied to the sleeves and it is allowed to dry for approximately two hours. Thereafter a bonding substrate which consists of approximately 20% of the uncured rubber and 80% M.E.B. [methyl ethyl ketone] by mass is applied to the sleeves with a brush. The sleeves are then allowed to dry for approximately one hour. The pre-treatment of the sleeves in this way prior to injecting the elastomeric compound ensures a firm bond between the metal sleeves and the compound which is essential, especially where the coupling is intended to be subjected to high startup torques or torque peaks during normal operation such as for use in crushers.The following two compounds have been found to be suitable for use as flexible, resilient compounds and are composed as follows:

The inner and outer sleeves are placed in a die and the die is then heated to approximately 145[deg]C. The uncured compound which may be compound A or B is injected into the die under pressure which can vary from 200 kg/cm to 5000 kg/cm depending on the size of the coupling. The pressure and temperature are maintained during the curing cycle which can vary from 30 to 65 minutes depending on the size of the coupling. Once the compound has been cured it has a shore hardness of between 40 and 70. The coupling is then removed from the die and any final machining of the coupling can take place. Thereafter the coupling is painted with a suitable paint.

Claims

1. A flexible coupling comprising an inner sleeve having radially outwardly extending projections, and an outer sleeve having radially inwardly extending projections, wherein the projections of the inner and outer sleeves are disposed between and spaced from each other; and resiliently flexible cushion means moulded in situ between the sleeves; the areas of the inner and outer sleeves interfacing with the cushion means being pre-treated with a bonding agent prior to moulding of the cushion means between the sleeves, the sleeves being adapted to be secured one to a driving member and the other to a driven member.

2. A flexible coupling as claimed in claim 1, in which the inner and outer sleeves are metal sleeves and wherein the flexible cushion means comprises a substantially annular elastomeric cushion disposed between the inner and outer sleeves.

3. A flexible coupling as claimed in claims 1 or 2 wherein the projections on the inner sleeve are tooth-like projections located circumferentially on at least part of its outer surface and the projections on the outer sleeve are also spaced tooth-like projections located circumferentially on at least part of its inner surface, the teeth of the inner and outer sleeves being disposed between and spaced from each other with the cushion means disposed between the teeth.

4. A flexible coupling as claimed in any one of claims 1 to 3 in which the outer sleeve has an annular flange.

5. A composite flexible coupling comprising two coupling sections in the form of couplings as claimed in the claim 4, the flanges of such coupling sections being connected to each other and one of the coupling sections being adapted to be connected to a driving member and the other to a driven member.

6. A flexible coupling as claimed in claim 1 in which the inner sleeve is one of two inner sleeves, the inner sleeves being separated from one another by the resiliently flexible cushion means and the inner sleeves being adapted to be connected one to a driving member and one to a driven member.

7. A flexible coupling as claimed in claim 6 in which the inner sleeves are adapted to be secured to a shaft by a taper-bush, keying or other locking arrangement.

8. A method of manufacturing a coupling comprising the steps of providing an inner sleeve having radially outwardly extending projections, an outer sleeve having radially inwardly extending projections, positioning the inner and outer sleeves so that the projections of the sleeves are disposed between and spaced from each other, introducing a resiliently flexible cushion means between the sleeves and pre-treating the areas of the inner and outer sleeves interfacing with the cushion means with a bonding agent prior to introducing the cushion means.

9. A method as claimed in claim 8, including the steps of pre-treating the inner sleeve and the outer sleeve areas with a bonding agent, moulding the inner sleeve to the outer sleeve by locating the outer sleeve and the inner sleeve in a die, heating the die to a suitable temperature, injecting an uncured elastomeric compound under pressure into the die, and maintaining the compound under pressure and at a suitable temperature throughout a curing cycle, the compound once cured forming a resiliently flexible cushion means between the inner and outer sleeves.

10. A method as claimed in claims 8 or 9 including the steps of pre-treating the sleeves by firstly degreasing and shotblasting them and secondly by applying a bonding agent to them prior to injecting the uncured elastomeric compound.

11. A method as claimed in claim 10, including the steps of pre-treating the sleeves by firstly degreasing and shotblasting them and secondly by coating the sleeves with a bonding agent, allowing the substance to dry and thereafter applying a suitable substrate to the sleeves which will aid the bonding process and then allowing the substrate to dry.

12. A method as claimed in claim 9 in which the compound is maintained at a pressure between 200 kg/cm and 5000 kg/cm and at a temperature of between 135[deg]C and

165.C during the curing cycle, the compound once cured having a shore hardness between 40 and 70.

13. A flexible coupling substantially as herein described and/or illustrated.

14. A method of manufacturing a flexible coupling substantially as herein described and/or ilustrated.