Title of Invention

ROPE DRIVE ELEMENT FOR DRIVING SYNTHETIC FIBER ROPES

Abstract This rope drive element for driving synthetic fiber ropes, preferably for a rope drive (1) of an elevator installation, ensures a consistently good selected tractive capacity which is largely independent of external influences which reduce friction. According to the invention, at least part of the rope running surface (7,17,27) is given a surface (14,37) with roughness grade N7 to N12. The surface is formed either by mechanical machining or by use of a suitable coating, preferably a plasma coating of corundum. In preferred embodiments the synthetic fiber rope or ropes run in rope grooves (7,17,27) in which the surface is formed, for example, only in the bed of the rope groove (7), in the area of the flanks (17), or over a wide area of the surface of the rope groove (27). By correspondingly suitable arrangement of these differently formed rope grooves (7,17,27) on a drive element (2), a desired tractive behavior can be systematically effected. (Figures 3a,3b,3c)
Full Text Rope Drive Element for Driving Synthetic Fiber Ropes
Description
The invention relates to a rope drive element for driving synthetic fiber ropes, preferably for a rope drive of an elevator installation, with the characteristics stated in the preamble to Claim 1.
Rope drives of this type are used in materials handling, especially in mining and the construction of cranes and elevators, or on aerial cableways and similar installations. It is known that the function of such rope drives is based on the driving force being transferred to the section of rope which is in contact at any time with the rope drive element, e.g. the traction sheave, rope drum, or similar. As the rope runs over the traction sheave it is bent, which causes compensating movements of the strands of a multi-layer rope.
The tractive capacity of such traction systems is restricted to operating ranges with sufficient frictional engagement between the traction sheave and rope. For example, on a rope traction elevator at least the difference in weight between the counterweight and car must be compensated by the frictional force on the traction sheave. The torque must also be transferred from the traction sheave to the rope by frictional engagement. For this reason, rope drives are designed in such manner that there is always sufficient tractive capacity for the various hoisting situations, e.g. normal travel, emergency

stopping, loading, and unloading. The range of frictional engagement is limited in essence by a minimum and maximum so-called allowable system coefficient of friction between the traction sheave and the rope passing over it.
To create the appropriate coefficient of friction on the traction sheave, on conventional traction sheaves shaped grooves, e.g. V-grooves or undercut semicircular grooves, are cut whose shape exerts a specific pressure on steel ropes so that the rope is gripped to a greater or lesser degree. However, these traction sheave grooves cannot be used for fully-synthetic suspension ropes. With these synthetic fiber ropes the desired coefficient of friction can be effected very well by the material used, as for example polyurethane, polyamide or similar, and its hardness. However, deviations in the coefficient of friction due to manufacture, or unforeseeable reductions in the system coefficient of friction due to oil, lubricants, or other liquids, could permanently impair the tractive capacity. Under unfavorable conditions it can therefore not be ruled out that the rope moves without the drive being able to affect this movement. This could lead to damage to persons or property.
The objective of the invention is therefore to propose a traction system for synthetic fiber ropes which ensures a consistently good tractive capacity which is largely independent of environmental influences.
According to the invention, this objective is achieved by a traction system with the characteristics stated in Claim 1,

which is especially characterized in that at least part of the rope running surface of the rope drive element has a surface of roughness grade N7 to N12. The dependent claims contain expedient and advantageous further developments and/or embodiments of the invention stated in Claim 1.
With the traction system according to the invention, the scatter of the system coefficients of friction of the combination of rope surface and running surface of the rope drive element, as for example a rope pulley, traction sheave, rope drum, deflected drive belt, or similar, is much smaller. Tests by the applicant have shown that with a rope running surface with a surface according to the invention, the system coefficient of friction in operation under normal conditions increases and advantageously stays constant at this higher level even if lubricants or other liquids become present.
The surface peak-to-valley height and/or the grain size of the coating are adapted to the Shore hardness of the rope sheath in such manner that by suitable combination in each case any requirement in respect of wear or function can be effected. To increase the service life of the rope sheath and to stabilize the long-term tractive capacity of the rope drive, for smaller peak-to-valley heights a friction partner with a lower Shore hardness is used, whereas for higher Shore hardnesses synthetic materials with harder surfaces are used for the sheaths of ropes or covering layers of strands.

To achieve the advantages according to the invention it is of no significance whether the synthetic fiber rope runs on a cylindrical surface of the rope drive element or in a shaped groove, as for example a semicircular groove. It is equally possible for there to be rope grooves with different shapes of profile, as for example a double semicircular groove, in which a complementary double or twin rope runs, etc. The advantages which can be achieved with the invention are, in principle, also achieved irrespective of the shape selected for the rope running surface of the rope drive element.
As it runs over a traction sheave, the synthetic fiber rope adapts itself to the profile of the semicircular groove and under load deforms on the contact surface, or in the profiled groove, from its original circular shape to an , oval section. According to the deformation, the specific pressures of the rope in the rope groove over the cross section of the groove are not constant but increase toward the base of the groove. This distribution of the specific pressures is more pronounced with a greater load on the rope.
In an advantageous preferred further development of the invention in its embodiment with shaped grooves, the surface according to the invention is formed over parts of a groove and used to effect the distribution of the load-dependent specific pressure over the cross section of the shaped groove to adjust the tractive behavior of the rope and thereby to fulfil a desired functional requirement.

Taking an embodiment of the traction sheave according to the invention with semicircular shaped grooves, in a first version the surface according to the invention is limited to an angular range of, for example, 45° on the bed of the groove. The system coefficient of friction of this shape of groove is consequently high at the base of the groove and decreases toward the two sides. Correspondingly, the tractive behavior of a synthetic fiber rope running in this groove with no load on the rope is deliberately less pronounced than with a greater load acting on the synthetic fiber rope when the rope is pulled further into the shaped groove and lies on the bed of the groove with a maximum of specific pressure.
A second preferred exemplary embodiment of a shaped groove according to the invention is to form the surface according to the invention symmetrically over two areas of the flanks of the cross section of the semicircular groove which are separated from each other. A load-dependent tractive behavior is also obtained with this embodiment. Here, in contrast to the exemplary embodiment previously described, the surface of the bed of the groove now has a lower peak-to-valley height. As a consequence, the traction of the heavily loaded synthetic fiber rope running in a semicircular groove formed in this way is less pronounced than that in the previous exemplary embodiment. On the other hand, the tractive behavior in the low load range is largely independent of the environmental influences.
In an advantageous third embodiment, the surface according to the invention is formed in an angular range of up to

140° over almost the entire cross section of the groove. According to the invention, a synthetic fiber rope running in this shape of groove displays a high level of tractive behavior which is independent of the load on the rope and the environmental influences acting on it.
The surface according to the invention, which corresponds to a roughness average of Ra = 1.6 to 50 /im, can be obtained either by a mechanical finishing process suitable for creating a resistant surface texture, as for example knurling or similar, or else by coating the surface, preferably with corundum plasma.
Coating the rope running surface affords the additional possibility of subsequently converting conventional traction sheaves or rope drums for the advantageous tractive behavior with synthetic fiber ropes. The coating can either be applied to the desired areas on the steel groove or else appropriately flexible stiffeners are first plasma coated and then these pre-prepared plasma strips are attached to the desired point of the surface over which the rope runs by bonding with adhesive, fastening with screws, and/or some other means.
In a further development of the invention the tractive behavior of a traction sheave with several shaped grooves formed in its circumference is systematically adapted to the selected requirements for the traction system by combining the embodiments of groove surfaces previously described.

Preferred exemplary embodiments of the invention are illustrated in the drawings and described in detail below. The drawings show:
Figure 1 A diagrammatic view of a rope pulley according
to the invention in the direction of its axis of rotation and a synthetic fiber stranded rope running over it;
Figure 2 - A half-sectional view parallel to the axis of
rotation of the traction sheave from Figure 1;
Figure 3a A diagrammatic partial section of the rope
groove of a first exemplary embodiment of a traction sheave according to the invention;
Figure 3b A diagrammatic partial section of the rope
groove of a second exemplary embodiment of a traction sheave according to the invention;
Figure 3c A diagrammatic partial section of the rope
groove of a third exemplary embodiment of a traction sheave according to the invention;
Figure 4a A partial section of a fourth exemplary
embodiment of the traction sheave according to the invention with a double rope groove with a twin rope lying in it;
Figure 4b A partial section of a fifth exemplary
embodiment of the traction sheave according to the invention with double groove;
Figure 4c A partial section of a sixth exemplary
embodiment of the traction sheave according to the invention with double groove;

Figure 4d A partial section of the double groove of the
traction shave according to the invention from
Figure 4a; Figure 4e A partial section of a seventh exemplary
embodiment of the traction sheave according to
the invention with double groove; Figure 4f A partial section of an eighth exemplary
embodiment of the traction sheave according to
the invention with double groove.
Figure 1 shows diagrammatically for the example of an elevator installation a rope drive 1 for driving five synthetic fiber ropes 4 passing over a traction sheave 2 each lying over an angle of wrap 3 of almost 180° on the outer circumference of the traction sheave 2. The five synthetic fiber ropes 4 serve as driven traction ropes for raising and lowering an elevator car 5, which is fastened to one end of each of the ropes 4, whereas the second end of each of the five synthetic fiber ropes 4 is connected to a counterweight 6. As they run over the traction sheave 2 the five synthetic fiber ropes 4 are permanently loaded by the mass forces of the elevator car 5 and counterweight 6. According to the invention, the traction system illustrated comprising traction sheave 2 and five synthetic fiber ropes
4 passing over it is so designed that under the load of car
5 and counterweight 6 sufficient frictional engagement is ensured to transfer the driving torque of a drive machine via traction sheave 2 to the synthetic fiber ropes 5.
On a rope traction elevator the maximum limit for the coefficient of friction is derived from the safety

requirement that when the counterweight 6 strikes the buffers the ropes 4 slip on the traction sheave 2. This ensures that if the elevator car 5 travels beyond the upper stop it is not pulled under the ceiling of the hoistway headroom and the suspension rope 4 is not loaded to the limit of its breaking load even though the traction sheave 2 continues to turn. The result would be total failure of the rope. On the other hand, the coefficient of friction must not be below a minimum value, so that the difference in weight between the car 5 and counterweight 6 can be neutralized on the traction sheave 2 by the frictional force components,
For this purpose, in the exemplary embodiment illustrated, to guide the synthetic fiber ropes 4, shaped grooves 7,17,27 are formed on the outer circumference of the traction sheave 2 which have a shape of groove which essentially corresponds to the outer curvature of the hoisting rope 4, i.e. that part of the cross section of the rope 4 lying on them. In the embodiments of the traction sheave 2 shown in Figures 2 to 3c the rope grooves 7,17,27 are formed as semicircular grooves.
Figure 2 illustrates a half-section of an embodiment of the traction sheave according to the invention 2. The traction sheave 2 has a hub 8 with a hole 9 drilled centrally through it to t^ke a drive shaft. The traction sheave 2 fits exactly on the drive shaft on which it is mounted and fastened in a non-rotating manner with a key and keyway 10 so as to transmit the drive torque. A rim 11 having essentially the form of a hollow cylinder is connected

monolithically via a perforated sheave body 12 to the hub 8.
Cut on the surface of the outer circumference of the traction sheave 2 formed by the cylindrical surface of the rim 11 at regular distances from each other in the direction of the axis are five rope grooves 7,17,27, which according to the invention and as described in greater detail below, all have a plasma coating 14. In elevator construction hitherto traction sheaves 2 with from two to twelve grooves have been usual. In the embodiment described here by reference to Figure 2 five grooves 7,17,27 with semicircular profile are formed (Figures 3a to 3c). However, other shapes of groove are also possible which the specialist knows and can provide according to the form of rope cross section being used in each case, without the essence of the invention thereby changing. Examples of these are shown in Figures 4a to 4f and described further below.
The rope drive 1 is designed in the usual manner so that for the various hoisting situations, e.g. normal travel, emergency stopping, loading, and unloading, sufficient tractive capacity is always present. To create the necessary, or maximum, tractive or drive capacity, i.e. also to keep the tractive capacity within relatively narrow limits for the fully synthetic suspension means which have become known, on the embodiments according to Figure 2 the surfaces of the grooves of the traction sheave 2 according to the invention are partially or completely coated with a plasma coating 14.

Partial coating of a groove 7,17,27 with plasma serves the purpose of using this to fulfil a desired functional requirement for a load-dependent distribution of specific pressure over the cross-section of the shaped groove to effect the tractive behavior of the rope 4.
As it runs over the traction sheave 2, the synthetic fiber rope 4 adapts itself to the profile of the semicircular groove 7,17,27 and under load deforms on the contact surface, or in the profiled groove, from its original circular shape to an oval section. According to the deformation, the specific pressures of the rope 4 in the rope groove 7,17,27 over the cross section of the groove are not constant but increase toward the base of the groove. This distribution of the specific pressures is more pronounced with a greater load on the rope.
Taking an embodiment of the traction sheave 2 according to the invention with semicircular shaped grooves, in the rope groove 7 shown in Figure 3a a plasma coating 14 is limited to an angular range of 45° on the bed of the groove. The coating of the bed of the groove is not limited to the angular range of 45° stated here; on the contrary, to obtain a desired frictional force the angular range of coating in the bed of the groove can be correspondingly selected. The system coefficient of friction of this rope groove 7 is consequently high at the base of the groove and decreases toward the two sides. Correspondingly, the tractive behavior of a synthetic fiber rope 4 running in this groove 7 with no load on the rope is deliberately less

pronounced than the greater load acting on the synthetic fiber rope 4 when the rope 4 is pulled further into the shaped groove 7 and as a result of the rope deformation previously mentioned adapts particularly closely to the bed of the groove and lies in the bed of the groove with a maximum of contact pressure.
In the rope groove 17 illustrated in Figure 3b a symmetrical coating 14 is formed over two flank areas each of 45° of the cross section of the semicircular groove and separated from each other by an angular range of 45°. A load-dependent tractive behavior is also obtained with the plasma coating 14 of parts of this rope groove 17. In contrast to the rope groove 7 described above, here only the bed of the groove is not coated with plasma." As a result, the traction of a synthetic fiber rope 4 running in a semicircular groove 17 having this form is less pronounced than that of the previous exemplary embodiment 7. On the other hand, the tractive behavior in the low-load range is largely independent of the environmental influences.
According to Figure 3c the plasma coating 14 of the rope groove 27 "with an angular range of up to 140° is applied over almost the entire cross section of the groove. A synthetic fiber rope 4 running in this shaped groove 27 displays according to the invention a pronounced tractive behavior at a high level which is independent of the rope load and the environmental influences acting on it. Instead of a complete coating of the groove surface, several

locally limited areas in this angular range can be coated with plasma.
According to the invention, by systematically arranging one or more of the differently coated rope grooves 7,17,27 as described above on a traction sheave 2, the tractive behavior of a rope drive 1 can be systematically adapted to specified functional requirements.
Thanks to the surface roughness according to the invention, which is here created by means of a plasma coating 14, the system coefficient of friction of the combination of rope surface and running surface of the traction sheave 2 in the normal state is higher and remains constant at this level, even if lubricants or other liquids become present.
The surface finish of the rope running surfaces, here the rope grooves 7,17,27, created by means of the plasma coating 14 according to the invention has peak-to-valley heights and grain sizes which are adapted depending on the wear and/or functional specifications to the Shore hardness of the rope sheath or the sheath of the covering layer of strands of polyurethane, polyamide, or similar. In this respect, for smaller peak-to-valley heights (lower Ra values) a friction partner has to be provided which has a lower Shore hardness. Similarly, for higher Shore hardnesses, harder synthetic surfaces have to be provided.
The surface roughness of the plasma coating 14 combined with fully synthetic hoisting ropes 4 has a roughness grade lying in the range N7 to N12 which corresponds to an

average surface peak-to-valley height of Ra = 1.6 to 50 µm. In the embodiment illustrated in Figures 1 to 3 an N9 plasma coating 14 is combined with a synthetic rope sheath with Shore hardness A. On the other hand, surface roughnesses of NIO and above should be combined with rope sheaths with greater hardness, e.g. Shore hardness D.
In Figures 4a to 4f exemplary embodiments of a rope sheave 18 according to the invention are illustrated with twin grooves 19,20,21,22,23 in which, as shown in exemplary manner in 4a, a so-called twin rope 24 runs. The twin rope 24 is symmetrically constructed from two multilayer synthetic fiber stranded ropes 25,26 twisted in opposite directions of twist, which are joined together by a common rope sheath 28 into the non-rotating twin rope 24 having a cross-section in the form of a dumbbell. The shape of the double groove is made complementary to the contour of the respective twin rope 24. The shape of the double groove 19,20,21,22,23 along the direction of the axis of the rope sheave 18 consists in each case of a central section and two outer profiles 29, 30 with the central section 31,32,33,34 between them. The outer profiles 29,30 are in each case formed from one half of a semicircular groove and are identical in all the embodiments illustrated in Figures 4a to 4f. The central section 31 has a contour with outward radial curvature whereas the central section 32 of the double groove 32 is curved radially inward (Figure 4b). The double groove 33 illustrated in Figure 4c has a central section 33 which forms a radially inward-directed channel 36. In Figure 4d the double groove 19 from Figure 4a is shown without the twin rope 24 lying in it. In the double

groove 22 the central section 34 has a trapezoid form radially directed outward. In the double groove 23 the two outer parts of a semicircular groove are joined to each other in a straight line by a flat, level central section 35. According to the invention, in the area 37 all the double-grooved embodiments 19,20,21,22,23 are provided with the rope running surface according to the invention by means of plasma coating. As on exemplary embodiments described earlier, this can take the form of a coating of the complete groove surface or of a number of locally limited areas.

List of Reference Numbers
1. Rope drive
2. Traction sheave
3. Angle of wrap
4. Synthetic fiber rope, multilayer
5. Elevator car
6. Counterweight
7. Rope groove, bed coated
8. Hub
9. Drilled hole
10. Key and keyway
11. Rim, cylindrically shaped
12. Sheave body, perforated
13. Axis of rotation
14. Plasma coating 15.
16.
17. Rope groove, coated on flanks
18. Rope sheave
19. Double groove
20. Double groove
21. Double groove
22. Double groove
23. Double groove
24. Twin rope
25. Synthetic fiber rope
26. ' Synthetic fiber rope
27. Rope groove, bed coated
28. Rope sheath
29. Outer profile

30. Outer profile
31. Central section
32. Central section
33. Central section
34. Central section
35. Central section
36. Channel
37. Plasma coating





Patent Claims
1. Rope drive element for driving synthetic fiber ropes, preferably for a rope drive (1) of an elevator installation, with a rope running surface running around an axis of rotation (13) over which one or more synthetic fiber ropes (4) are in contact for the purpose of transmitting the driving force, characterized in that at least part of the rope running surface has a surface (14,37) of roughness grade N7 to N12.
2. Rope drive element according to Claim 1, characterized in that the rope running surface is formed by one or more rope grooves (27,19,20,21,22,23).
3. Rope drive element according to Claim 2, characterized in that in at least one rope groove (7) the surface (14,37) bounded by the groove bed of the rope groove (7) is formed over an angular range of up to 45°.
4. Rope drive element according to Claim 2, characterized in that
in at least one rope groove (17) the surface (14,37) is formed symmetrically over two flank areas of the rope groove (17) which are at a distance from each other.
5. Rope drive element according to Claim 2,
characterized in that
in at least one rope groove (27) the surface (14,37) is

formed over almost the entire,rope groove (27,19,20,21,22,23) in an angular range of up to 140° .
6. Rope drive element according to Claims 3,4,5,
characterized by
at least three rope grooves (7,17,27,19,20,21,22,23) one behind the other in the direction of the axis of rotation (13) with differently formed surfaces (14,37).
7. Rope drive element according to one of the Claims 1 to
6, characterized in that
the surface is formed as a coating (14,37) with a peak-to-valley height of Ra = 1.6 to 50 µm.
8. Rope drive which has a driven rope sheave (2,18) or a
rope drum with a rope running surface for transmission
of a drive torque onto one or more synthetic fiber
ropes (4) which for the purpose of transmitting the
driving force are in contact with the rope running
surface,
characterized in that at least part of the rope running surface has a surface (14,37) with a roughness average of Ra = 1.6 to 50 µm.
9. Rope drive according to Claim 7,
characterized in that
a surface (14,37) with a roughness average of Ra = 6.3 is combined with a synthetic fiber rope sheath with Shore hardness A.

10- Rope drive according to Claim 7,
characterized in that a surface (14,37) with a roughness average of Ra = 12.5 is combined with a synthetic fiber rope sheath with Shore hardness D.
11. Method of manufacturing a traction sheave for drive machines for hoisting ropes of synthetic fibers, preferably for a rope drive (1) of an elevator installation, on which one or more laid multi-layer stranded synthetic fiber ropes (4) wrap at least part of a running surface of the traction sheave (2,18) and can be driven by means of a traction sheave (2,18), characterized in that the rope running surface (7,17,27,19,20,21,22,23) of the traction sheave (2,18) is provided with a surface coating (14,37) of roughness grade N7 to N12.
12. Method according to Claim 11,
characterized in that the rope running surface is plasma coated (14,37).
13. Method according to Claim 12,
characterized in that the coating material applied is corundum.

14. Rope drive element for driving synthetic fiber ropes, substantially as herein described with reference to the accompanying drawings.


Documents:

915-mas-2000-abstract.pdf

915-mas-2000-claims filed.pdf

915-mas-2000-claims grand.pdf

915-mas-2000-correspondnece-others.pdf

915-mas-2000-correspondnece-po.pdf

915-mas-2000-description(complete) filed.pdf

915-mas-2000-description(complete) grand.pdf

915-mas-2000-drawings.pdf

915-mas-2000-form 1.pdf

915-mas-2000-form 19.pdf

915-mas-2000-form 26.pdf

915-mas-2000-form 3.pdf

915-mas-2000-form 4.pdf

915-mas-2000-form 5.pdf

915-mas-2000-other documents.pdf

915-mas-2000-verification document.pdf

abs-915-mas-2000.jpg


Patent Number 201829
Indian Patent Application Number 915/MAS/2000
PG Journal Number 05/2007
Publication Date 02-Feb-2007
Grant Date 10-Aug-2006
Date of Filing 27-Oct-2000
Name of Patentee INVENTIO AG
Applicant Address SEESTRASSE 55, CH-6052 HERGISWIL, SWITZERLAND
Inventors:
# Inventor's Name Inventor's Address
1 CLAUDIO DE ANGELIS NEGERBERGASSE 1, CH 6004 LUZERN, SWITZERLAND
PCT International Classification Number B66D001/30
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 99810978.9 1999-10-29 EUROPEAN UNION