CN111699150A

CN111699150A - Traction wheel elevator

Info

Publication number: CN111699150A
Application number: CN201880089064.XA
Authority: CN
Inventors: S.梅基马蒂拉
Original assignee: Kone Corp
Current assignee: Kone Corp
Priority date: 2018-03-22
Filing date: 2018-03-22
Publication date: 2020-09-22
Also published as: WO2019180300A1

Abstract

The invention relates to a traction sheave elevator comprising an elevator car (1), a hoisting machine (4) having a traction sheave (5) and hoisting ropes (3) arranged to transfer drive from the traction sheave (5) to the elevator car (1), and the traction sheave (5) comprises circumferential rope grooves (7), which rope grooves (7) have a coating (9), which coating (9) has a contact surface (10) for contact with each hoisting rope (3). The coating (9) in the rope groove (7) is a metal layer on the surface of the rope groove (7), and the contact surface (10) of the coating (9) of the rope groove (7) is harder than the base material of the traction sheave (5).

Description

Traction wheel elevator

Technical Field

The present invention relates to a traction sheave elevator according to the preamble of claim 1.

Background

Generally, elevators comprise a hoisting or driving machine with a traction sheave and hoisting ropes to drive the elevator car under the control of an elevator control system. The drive machine usually comprises a hoisting motor which rotates a traction sheave which engages with a hoisting rope connected to the elevator car and advantageously also to a counterweight or counterweight. Thus, the driving force is transmitted from the hoisting motor to the elevator car via the traction sheave and the hoisting ropes.

One problem in the known elevator arrangement is the slipping of the hoisting ropes in the rope grooves of the traction sheave. The sliding of the rope in the rope grooves of the traction sheave depends on the load conditions and the rope elasticity.

The transmission of the driving force is based on the friction between the rope grooves of the traction sheave and the hoisting ropes made of stranded wires. The rope grooves of the traction sheave have a certain friction on the hoisting ropes. The rope friction is usually lower than the torque affected by the hoisting motor, because the friction has an upper limit above which the rope slides on the rope grooves of the traction sheave. Thus, by increasing the coefficient of friction between the hoisting rope sheave and the rope grooves of the traction sheave, the mechanical efficiency of the elevator system can be improved. Typically, this is achieved by undercutting the bottom of the rope groove and selecting suitable materials and lubricants. The most common materials used for the traction sheave and the hoisting ropes in pairs are cast iron for the traction sheave and carbon steel for the hoisting ropes.

The elevator car and the counterweight loaded in relation to the car can be made lighter if the traction and the friction coefficient can be made higher. This is beneficial for elevator lay-out and energy consumption. Thus, the moving mass can be reduced, which means less energy is required to move the payload.

The hoisting ropes also slide in the rope grooves due to the elasticity of the system. The rope stresses on different sides of the traction sheave differ, which results in different elastic elongations of the rope at different positions. When a highly stressed rope is moved to a position where the stress is lower, it will contract. In order to prevent slipping due to the elasticity of the rope, the rope ideally has a high elastic coefficient.

The hoisting ropes also slip due to dynamic conditions. There are differences in the diameter, groove contact and spring constant of the ropes, which results in uneven rope stress that is compensated by slipping during movement of the elevator car.

The service life of the hoisting ropes depends to a large extent on the wear between the ropes and the rope grooves of the traction sheave. The wear itself depends on the pressure and the force between the rope and the rope groove of the traction sheave. The groove pressure and the sliding together determine the wear rate. The more the rope slides, the higher the contact pressure, the faster the rope wears and the diameter of the rope also decreases. Typically, for example, when wear reduces the rope diameter to 6% below the nominal diameter, the rope must be discarded. With regard to power consumption and rope life, the greatest friction is optimal, which results in a minimization of rope slip in the rope grooves of the traction sheave.

Rope wear is related to the wear of the rope grooves of the traction sheave. If the material of the traction sheave is too soft, the rope grooves usually wear too fast. Generally, the rope is made of high carbon pearlite, cold drawn wire or ferritic stainless steel wire, which has high hardness and high wear resistance. The hardness of the rope groove of the traction sheave is adjusted to the hardness of the rope so that wear of the entire system is minimized. The traction sheave and the deflection pulleys are typically made of cast iron having a hardness in the range of 200 to 350 HB. Typical materials for the traction wheel are carbon steel, cast iron such as gray cast iron, spheroidized cast iron, and heat treated austempered iron. Coatings for rope grooves have been used to increase wear resistance and friction.

In addition, thermal surface hardening treatments such as flame hardening, induction hardening, and laser hardening have been employed to increase the hardness and wear resistance of traction wheels.

To prevent wear of the traction sheave and the rope, a suitable lubricant is used. The lubricant is typically in the rope. During the rope manufacturing process, the rope or its filaments or strands pass through the lubrication grooves. As a result, the surface strands of the elevator hoisting ropes typically contain 1.0-2.0% of a grease lubricant.

Disclosure of Invention

It is an object of the invention to reduce and eliminate the drawbacks and problems of the prior-art solutions and to achieve a traction sheave elevator with a traction sheave, in which the friction between the rope grooves of the traction sheave and the hoisting ropes is increased by using a material that is harder than the base material of the traction sheave. Another object of the invention is to use a coating in the rope grooves of a traction sheave, which coating has a better wear resistance than the substrate of the traction sheave. A further object of the invention is to achieve a longer life of the hoisting ropes and traction sheave. The elevator with traction sheave according to the invention is characterized by what is presented in the characterization part of claim 1. Other embodiments of the invention are characterized by what is set forth in the other claims.

The inventive content of the application can also be defined differently than in the claims presented below. The inventive content may also consist of several separate inventions, especially if the invention is considered in the light of expressions or implicit sub-tasks or from the point of view of advantages or categories of advantages achieved. In this case, some of the attributes contained in the claims below may be superfluous from the point of view of separate inventive concepts. Also, the different details presented in connection with each embodiment may be applied in other embodiments as well. Furthermore, it is stated that at least some of the dependent claims may be regarded as inventive in their own right, at least in some cases.

In order to achieve the above object, the invention provides a traction sheave elevator comprising an elevator car, a hoisting machine having a traction sheave and hoisting ropes arranged to transfer drive force from the traction sheave to the elevator car, and the traction sheave comprises circumferential rope grooves having a coating with a contact surface for contacting each hoisting rope. Advantageously, the contact surface of the coating of the rope grooves is harder than the base material of the traction sheave. Advantageously, the rope groove coating is performed by using metal spraying or thermal spraying, preferably by using a plasma spraying process.

It is also advantageous if the coating in the rope groove is a metal layer on the surface of the rope groove and comprises a metal alloy sprayed onto the surface of the rope groove. Advantageously, the surface of the substrate is enhanced/made stronger by spraying a coating thereon. Preferably, the coating in the rope grooves has a martensitic metallurgical microstructure and has a greater friction coefficient and greater wear resistance than the corresponding properties of the base material of the traction sheave.

Additionally or alternatively, the parameters of spraying the metal alloy onto the surface of the rope groove are selected such that the surface of the rope groove substrate will be modified. For example, in the case of cast iron as the substrate, in the surface layer of the substrate, at least some of the carbon and/or other particles of the substrate fine structure deform and/or escape from the substrate; some of these particles may migrate into the coating. Thus, the substrate of the traction wheel has a reduced carbon content in the vicinity of the coating.

Additionally or alternatively, the sprayed metal coating is partially mixed with the substrate, thereby forming an intermediate layer or region between the coating and the outer surface of the substrate of the traction sheave groove. The intermediate layer may consist of several sublayers or the composition and material properties of the intermediate layer may change gradually and/or stepwise several times.

The intermediate layer or region may include materials from the substrate and the coating. Advantageously, it comprises a sub-layer which is the treated or converted substrate.

Advantageously, the intermediate layer or region comprises a sub-layer which is a mixture of material from the substrate and the coating.

One advantage of the intermediate layer or region is improved bonding of the coating.

The solution according to the invention has, inter alia, the following advantages: which improves the coefficient of friction and further improves the friction between the hoisting ropes and the rope grooves of the traction sheave. The friction force is the force applied to the hoisting rope, which force is obtained by the combined effect of the friction of the material pairs formed by the rope grooves and the hoisting ropes. Another advantage of the invention is that a higher coefficient of friction makes it possible to obtain a greater rope force at the same torque of the hoisting machine. In practice, the relationship between the weight of the elevator car and the weight of the payload can be made smaller. Another advantage is that a better efficiency factor is obtained. Another advantage is that the wear of the side surfaces of the rope groove of the traction sheave is reduced. Another advantage is that the substrate of the traction sheave can be simple and inexpensive due to the inventive coating of the rope grooves. Another advantage is that the change in the coefficient of friction of the coated rope grooves is more stable than that of rope grooves without a coating. Another advantage is that only the sides of the rope groove can be coated, since the contact area between the hoisting rope and the rope groove is narrow. This makes the manufacture of the traction sheave easier. Another advantage is that the hardness of the coating is in the less abrasive areas of the strands of the rope filaments. Another advantage is that the hardness of the coating is in the area where it wears less strongly. Another advantage is that the coating is effectively resistant to corrosion, and therefore there is no need to protect the rope groove from corrosion, for example during storage and transport.

Drawings

In the following, the invention will be described in detail by means of an exemplary embodiment with reference to the enclosed simplified and schematic drawings, in which

Fig. 1 presents in a simplified and diagrammatic side view a typical traction sheave elevator, in which the solution of the invention can be used,

figure 2 presents in a simplified and diagrammatic cross-section the peripheral part of a traction sheave used in an elevator according to the invention,

fig. 3 shows, in a simplified and schematic cross-sectional view, an outer peripheral part of the traction sheave according to fig. 2, with hoisting ropes in the rope grooves,

figure 4 shows in an enlarged and simplified and schematic cross-sectional view a part of the surface layer of the rope groove of the traction sheave according to the invention,

fig. 5 shows, in an enlarged, simplified and schematic cross-sectional view, the interface between the substrate of the rope groove of fig. 4 and the coating of the rope groove, and

figure 6 shows a graph of the friction coefficient of the rope groove of the original cast iron and an advantageous coating of the rope groove according to the invention.

Detailed Description

Fig. 1 presents in a simplified and diagrammatic side view a typical traction sheave elevator in which the solution of the invention can be used. The elevator comprises at least an elevator car 1 and a counterweight 2, which elevator car 1 and counterweight 2 are connected to each other by means of one or more hoisting ropes 3, which hoisting ropes 3 form a hoisting roping. Preferably, the hoisting ropes 3 are wire ropes having a wire forming at least a part of the outer surface of the rope 3. Advantageously, the hoisting ropes 3 are steel wire ropes. A first end of the hoisting ropes 3 is fastened to the elevator car 1 and a second end of the hoisting ropes 3 is fastened to the counterweight 2. The counterweight 2 may also be a balance weight. Hereinafter, when only the balance weight 2 is referred to, both are referred to.

The elevator also comprises a hoisting machine 4 having a traction sheave 5 and a traction motor 4a rotating the traction sheave 5. In this embodiment the hoisting machine 4 is placed above the elevator car 1 and the counterweight 2, but the hoisting machine 4 may also be below the elevator car 1 and the counterweight 2 or in some other suitable position in relation to the elevator car 1 and the counterweight 2. In this embodiment the hoisting ropes 3 are arranged to pass over the traction sheave 5 and the diverting pulley 6 such that the contact angle or wrap angle between the traction sheave 5 and the hoisting ropes 3 is long enough to provide sufficient friction to transfer driving force from the hoisting motor 4a to the elevator car 2 via the traction sheave 5 and the hoisting ropes 3.

Fig. 2 and 3 show, in a simplified and schematic cross-sectional view, an outer peripheral portion of a traction wheel 5 according to the invention. Fig. 2 shows the peripheral part of the traction sheave 5 without the hoisting ropes 3 and in fig. 3 the profile of the hoisting ropes 3 is shown.

In this embodiment the traction sheave 5 comprises on its outer circumference four similar circumferential grooves 7 for the hoisting ropes 3. The rope grooves 7 are parallel to each other and the cross section of each groove 7 is formed as suitable as possible for the hoisting rope 3. The cross-section of the groove 7 may be, for example, semicircular, a so-called U-shaped groove, or may resemble the letter V, a so-called V-shaped groove. For traction between the hoisting rope grooves 7 and the hoisting ropes 3, the grooves 7 are often undercut so that the ropes 3 do not hit the bottom of the rope grooves 7. As shown in fig. 2 and 3, the rope groove 7 in this embodiment of the invention is an undercut U-shaped groove having an undercut 8 at the bottom of the rope groove 7.

Each circumferential rope groove 7 of the traction sheave 5 comprises a metallic circumferential coating 9, which metallic circumferential coating 9 is arranged to cover at least the contact area between the hoisting ropes 3 and the coating 9. Advantageously, the coating 9 covers at least a part of each side of the rope groove 7 along the entire circumferential length of the rope groove 7. Furthermore, each coating 9 comprises a metal circumferential contact surface 10 for each contact point with the hoisting ropes 3. Advantageously, the coating 9 comprises a metal contact surface 10 at least on each side of the rope groove 7.

Fig. 4 and 5 show in an enlarged, simplified and schematic cross-sectional view a part of the surface layer of the rope groove 7 of the traction sheave 5 according to the invention. Fig. 4 shows a part of the uncoated surface layer of the rope grooves 7 of the traction sheave 5, and fig. 5 shows the same part of the surface layer coated with the coating 9 used on the rope grooves 7 of the traction sheave 5 according to the invention.

Advantageously, the coating 9 is made onto the surface 7a of the rope groove 7 by metal spraying, wherein the pulverized coating is melted and sprayed onto the surface 7a of the rope groove 7 using various techniques. These types of metal spraying or thermal spraying techniques are not explained in more detail herein. The thickness of the coating 9 on the sides of the rope grooves 9 of the traction sheave 5 is preferably in the range of 20-100 μm, advantageously in the range of 25-80 μm. In this case, the uneven surface of the coating 9 and the thickness distribution of the coating 9 do not adversely affect the internal stress of the bottom surface 7a of the rope groove 7 and the coating 9.

Advantageously, the coating 9 is a metal alloy comprising one or more suitable metals, metalloids and non-metals. Preferably, the metallurgical structure of the coating 9 substantially corresponds to a martensitic stainless steel, such as 2Cr13 or grade 420 stainless steel. In an advantageous embodiment of the invention, the coating 9 comprises at least carbon, chromium, manganese and silicon as alloying elements. Preferred contents of alloying elements are as follows (in wt%):

C:0.16…0.25

Cr:12.0…14.0

Mn:1.0…1.5

Si:0.0…1.0

when sprayed onto the surface 7a of the rope groove 7, the coating is partly melted, and when cooled, after spraying, the coating solidifies and forms a martensitic metallurgical microstructure. The microhardness of the coating 9 is 430 … 550HV 550, but if a suitable alloy element mixing ratio and a suitable hardening method are used, the microhardness can be increased to 700 … 850 HV. Thus, the hardness of the coating 9, preferably the hardness of the contact surface 10 of the coating 9, is greater than the hardness of the substrate of the traction wheel 5. The base material of the traction sheave 5 is, for example, cast iron or steel, and the surface 7a of the original rope groove in the outer periphery of the base material is usually of the same material.

The pulverized metallic paint is melted and sprayed onto the uncoated bottom surface 7a of the rope groove 7 with pressure and high speed, so that at least a part of the hard paint particles hit the bottom surface 7a with great force, thereby causing the bottom surface 7a of the rope groove 7 to be deformed. The traction sheave 5 according to the invention thus comprises rope grooves 7, the rope grooves 7 having a metal coating 9 for contact with the hoisting ropes 3, which coating 9 comprises an intermediate layer 12 between the substrate of the traction sheave 5 and a contact surface 10 of the coating 9, which contact surface 10 forms an upper layer of the coating 9. The intermediate layer 12 comprises a mixture of coating material and substrate material in a gradually changing relationship such that the proportional amount of substrate material is greater near the surface of the original substrate material of the traction wheel 5 than near the contact surface 10 of the coating 9.

Between the intermediate layer 12 and the substrate of the traction wheel 5, the original surface 7a of the substrate is at least partially deformed. This improves the fastness of the coating. In fig. 5, the intermediate layer 12 has an upper imaginary limit line 9a against the coating and a lower imaginary limit line 5a against the upper part of the base material of the rope groove 7 of the traction sheave 5. The clear limit lines like the

imaginary lines

5a, 9a do not actually exist but the composition of the material gradually changes from the substrate to the coating or from the material of the traction sheave 5 to the material of the coating 9.

During the metal spraying stage, at least some of the carbon particles 11 also deform and/or escape from the substrate of the traction sheave 5. Some of the carbon particles 11 move to the coating, in particular to the intermediate layer 12 of the coating 9, and some of the carbon particles 11 are completely worn away. The substrate of the traction wheel 5 therefore has a reduced carbon content in the vicinity of the coating 9. However, the substrate of the traction wheel 5 remains unchanged in its deeper regions.

Fig. 6 presents test results as a graph of coefficient of friction against sliding contact. In the test, lubricated high strength steel cords were slid on the surface of spheroidal graphite cast iron (e.g., GJS 700) at various sliding speeds and the coefficient of friction of the contact was determined. Lubricants are typical mineral-based lubricants used in elevator hoisting ropes. Curve 13 represents the coefficient of friction between the steel cord and the original cast iron surface at different sliding speeds. Correspondingly, curve 14 shows the coefficient of friction between the steel cord and the coating 9 according to the invention at different sliding speeds, which coating 9 is sprayed onto the surface of the original cast iron surface using a suitable metal spraying technique. In the test, the sliding speed of the steel rope corresponds to the normal sliding of the rope on the traction sheave during the movement of the elevator car.

The coefficient of friction stabilizes as the material wears during testing. Thereafter, a stable coefficient of friction may be determined. In this test, the measured coefficient of stable friction of the uncoated cast iron material was 0.130, whereas the measured coefficient of stable friction of the cast iron material coated with the coating layer 9 according to the invention was 0.175. In addition, the coefficient of friction and the wear rate of the coating 9 proved to be more stable than those of the surface of the original cast iron.

In addition, the wear resistance of the coating 9 and the original uncoated cast iron surface was measured in the test. The measurement is carried out at a sliding speed of about 2.0mm/s and a contact pressure of 20-40 MPa. The measured wear of the uncoated cast iron material was 0.23mm³Whereas the measured wear of the coating 9 according to the invention was 0.14mm³。

The test results clearly show that the coating 9 according to the invention on the cast iron surface results in a higher friction coefficient for the rope grooves 7 of the traction sheave 5 and that the wear resistance of the coated rope grooves 7 is also better than the wear resistance of the uncoated rope grooves 7 of the cast iron traction sheave. As previously mentioned, the hardness of the coating 9 according to the invention is also greater than the hardness of the substrate of the traction wheel 5.

All these features above make it possible to achieve a traction sheave elevator in which, due to the inventive solution in the traction sheave 5, the friction between the hoisting ropes 3 and the rope grooves 7 is raised, and in which the friction surface of the contact surface 10 or the rope grooves 7 is also harder than the corresponding contact surface of the uncoated rope grooves, so that the wear resistance of the rope grooves 7 of the traction sheave 5 according to the invention is also better than the uncoated rope grooves of the prior art solutions.

It is obvious to the person skilled in the art that the invention is not limited to the examples described above, but that it may be varied within the scope of the claims presented below.

Claims

1. Traction sheave elevator comprising an elevator car (1), a hoisting machine (4) having a traction sheave (5) and hoisting ropes (3) arranged to transfer drive force from the traction sheave (5) to the elevator car (1), and the traction sheave (5) comprises circumferential rope grooves (7), which rope grooves (7) have a coating (9), which coating (9) has a contact surface (10) for contact with each hoisting rope (3), characterized in that the coating (9) in the rope grooves (7) is a metal layer on the surface of the rope grooves (7), and that the contact surface (10) of the coating (9) of the rope grooves (7) is harder than the base material of the traction sheave (5).

2. Traction sheave elevator according to claim 1, characterized in that the coating (9) in the rope grooves (7) is placed in the area where the wear of the strands of the hoisting ropes (3) is minimal.

3. Traction sheave elevator according to claim 2, characterized in that the coating in the rope groove (7) is placed in the area where the wear of the coating (9) is minimal.

4. Traction sheave elevator according to any of the preceding claims, characterized in that the coating (9) in the rope groove (7) is placed in the side area of the rope groove (7).

5. Traction sheave elevator according to any of the preceding claims, characterized in that the coating (9) in the rope grooves (7) has a coefficient of friction which is greater than the coefficient of friction of the base material of the traction sheave (5).

6. Traction sheave elevator according to any of the preceding claims, characterized in that the coating (9) in the rope grooves (7) has a wear resistance that is greater than the wear resistance of the base material of the traction sheave (5).

7. Traction sheave elevator according to any of the preceding claims, characterized in that the coating (9) in the rope grooves (7) comprises a metal alloy sprayed onto the surface of the rope grooves (7).

8. Traction sheave elevator according to any of the preceding claims, characterized in that the coating (9) in the rope grooves (7) has a martensitic metallurgical microstructure.

9. Traction sheave elevator according to any of the preceding claims, characterized in that the coating (9) in the rope grooves (7) comprises essentially 0.16 … 0.25 wt.% carbon; 12.0 … 14.0.0 wt% chromium; 1.0 … 1.5.5 wt% manganese and 0.0 … 1.0.0 wt% silicon.

10. Traction sheave elevator according to any of the preceding claims, characterized in that the substrate of the traction sheave (5) has a reduced carbon content in the vicinity of the coating (9).

11. Traction sheave elevator according to any of the preceding claims, characterized in that between the base material of the traction sheave (5) and the contact surface (10) of the coating (9) of the rope groove (7) there is an area in which the composition and/or material properties change gradually and/or stepwise several times.