CN1140691A - Elevator device - Google Patents

Abstract

Disclosed is an elevator which comprises a steel wire and a rotational pulley around which the steel wire stretches; wherein the steel wire is coated with a layer of steel wire which is Hv 420-460 in hardness and 165kgf/mm<2> in tensile strength; the pulley is made of dense cast vermicular graphite with a speed of 4 800-5 400m/s and a hardness of HB200-250, the dense cast vermicular graphite contains hypoeutectic and the pearlite range under cast state is more than 90%. The steel wire and the pulley which match with each other in use are long in service.

Description

Elevator device

This application is that the application date is September 12, 1991, the application number is 91108989-4, and the title of invention is a divisional application of the invention patent application of "dense worm-like graphite cast iron and the elevator pulley made thereof".

The present invention relates to an elevator device in which the pulleys are made of dense worm-like graphite cast iron.

For example, a steel wire rope hangs the elevator car and extends around a pulley, and the pulley driving the wire rope is generally made of flake graphite cast iron (hereinafter referred to as FC for iron castings) with a pearlite basic structure. FC is more suitable for steel wire rope, because flake graphite makes FC have self-lubricating effect, and FC is easy to process and not too expensive. The above-mentioned pulley has a rope groove for receiving the wire rope to provide the required friction transmission force for driving the wire rope. The rope groove has a V-shaped cross-section, or is recessed to protect the wire rope from contacting the bottom of the rope groove. That is, the wire rope is in contact with the side surface of the rope groove to increase the pressure therebetween, thereby increasing the frictional force. Although the wedge effect between the wire rope and the rope groove can be used to increase friction, this has the problem that the wire rope increases the wear of the pulley, thereby shortening the life of the pulley.

We know that the wear resistance of ductile iron (hereinafter referred to as FCD for ductile iron castings) is better than the above-mentioned FC, and the basic structure of FCD is as-cast pearlite (Japanese Patent Unexamined Publication Nos. 57-188645 and 1-123048). However, due to the dense structure and high hardness of FCD, the cutting performance of general machining is worse than that of FC. In addition, the casting cost of FCD is relatively high. Therefore, FCD is not suitable as a material for manufacturing elevator pulleys.

Densified vermicular graphite cast iron (hereinafter referred to as CV) has been proposed in Japanese Patent Unexamined Publication Nos. 60-248864 and 61-3866. CV is between FC and FCD in terms of mechanical properties, physical properties, cutting performance and castability.

Although the above properties of CV are between FC and FCD, its wear resistance is close to that of FC, and its castability is close to that of FCD. Furthermore, the stability of the pearlitic structure of CV (the pearlitic structure is said to have "stability" if the basic structure can be easily converted into the pearlitic structure) is not sufficient. Therefore, CV is not yet fully satisfactory as a cast iron having properties intermediate between FC and FCD.

It is an object of the present invention to provide an elevator apparatus in which the sheaves and ropes used in conjunction with each other have a high service life.

The object of the present invention is achieved through the following technical solutions, an elevator device comprising a steel wire rope and a rotatable pulley, the steel wire rope extends around the pulley, wherein the steel wire rope has a hardness of Hv420 to 460, tensile Outer steel wire with a strength of 165kgf/ ^mm2 , the pulleys are composed of ultrasonic waves with a passing speed of 4,800 to 5,400 m/s, a hardness of H _B 200 to 250, including a hypoeutectic composition and having a percentage of as-cast pearlite domains not less than Made of 90% dense worm-like graphite cast iron.

The advantage of the present invention is that the service life of the steel wire rope and the pulley made of the above materials can be doubled.

The dense worm-like graphite cast iron used in the present invention has a hypoeutectic composition, and its as-cast pearlite area percentage (from the cast iron microstructure, that is, the ratio of the area of the pearlite part to the entire area except cast iron graphite) , that is, the area of the pearlite part/the entire area of the cast iron except graphite × 100) is not less than 90%.

Among the components of the above composition, C is the main component for precipitating graphite, and Si is the main component for stabilizing the structure of CV. Meanwhile, it is important that, in order to stabilize the as-cast pearlite structure whose pearlite region percentage is not less than 90%, the carbon equivalent must be within the range of the hypoeutectic composition. In conventional CV, graphite has a dense worm-like structure with a CV composition in the hypereutectic range. On the other hand, in the CV used in the present invention, graphite is made to have a dense worm-like structure whose composition is in the hypoeutectic range to stabilize the pearlite structure.

Fig. 1 is a photomicrograph showing the metal structure of the dense vermicular graphite cast iron used in the present invention;

Fig. 2 is the front view of elevator pulley;

Figure 3 is a side view, partly in section, of an elevator pulley;

Figure 4 is a schematic diagram showing an elevator device;

Figure 5 is a plan view showing the elevator winching device;

Fig. 6 is the schematic diagram of pulley wear testing device;

Figure 7 is an enlarged cross-sectional view cut along the line B-B in Figure 6;

Fig. 8 is a schematic diagram for explaining the state of pulley wear;

Figure 9 is a graph showing the relationship between test frequency and pulley wear;

Fig. 10 is the schematic diagram of rope life testing device;

Figure 11 is an enlarged cross-sectional view cut along the line C-C in Figure 10;

Figure 12 is an enlarged cross-sectional view of a steel wire rope;

Figure 13 is a graph showing the results of the rope life test;

Fig. 14 is a graph showing the relationship between tensile strength and sound velocity.

Several examples of the novel dense vermicular graphite cast iron used in the present invention (compact vermicular cast iron hereinafter referred to as FCV) will be described below.

The main raw materials such as ductile iron, steel scrap, recycled steel scrap, Fe-Si, Fe-Mn, limestone, etc. and various auxiliary materials with a certain ratio of each are prepared in the cupola with acid lining Melt to obtain a melt. Then, a series of additional treatment processes are carried out on the melt, such as adding a certain proportion of treatment agent for desulfurization treatment, graphite spheroidization treatment, inoculation treatment, etc. within a predetermined time, so as to obtain a melt with the composition shown in Table 1. Each melt was poured into a mold and then solidified while adjusting the cooling rate by a chilled iron to prepare a test piece. For the test piece in the casting state, its mechanical properties, graphite spheroidization rate, pearlitization rate of the basic structure, etc. should be tested. In Table 1, samples 1 and 2 are comparative examples, and sample 3 is an example of the present invention.

Table 1 Sample No. Composition (weight percent) C Si mn sn Cu S Mg P Fe 1 3.68 2.64 0.86 -- -- 0.008 0.022 -- balance 2 3.62 2.35 0.02 -- 0.55 0.030 0.026 -- balance 3 3.41 2.29 0.5 0.07 1.06 0.031 0.020 0.05 balance

Note: No. 1 and No. 2 are comparative examples, and No. 3 is an embodiment of the present invention.

Each of Samples 1 and 2 had a carbon equivalent (C + 1/3 Si) of more than 4.3% to provide a hypereutectic, while Sample 3 had a carbon equivalent of not more than 4.3% to provide a hypoeutectic. However, in order to stabilize P, the carbon equivalent (C + 1/3 Si) is preferably in the range of 4.0 to 4.3%. Various measurement results of Samples 1 to 3 are shown in Table 2.

Table 2 Sample No. Mechanical behavior Spheroidization rate (%) Percentage of spherical photobody area (%) Tensile strength (kgf/mm ² ) Elongation (%) Hardness (H _B ) 1 50.5 7.6 207 69 68 2 48.2 3.2 235 67 74 3 52.5 3.0 248 61 94

Note: No. 1 and No. 2 are comparative examples, and No. 3 is an embodiment of the present invention.

  * The nodularization rate is obtained by taking a circle as a standard and combining the microstructure of stone

It is obtained by grouping ink shapes and then averaging the resulting values.

It can be seen from Table 2 that the percentages of pearlite domains of samples 1 and 2 composed of hypereutectic crystals are 68% and 74%, respectively, while the percentage of pearlite domains of sample 3 composed of hypoeutectic crystals increases to 94%, thus providing FCV with a stable pearlite structure. From the photomicrograph in Fig. 1 (magnification 100 times), it can be seen that for the metal structure of the as-cast sample 3, the flake graphite has rounded ends and crystallizes with an almost complete pearlitic basic structure. It can also be seen from Table 2 that the various mechanical properties (tensile strength, elongation and hardness) of Sample 3 are excellent.

It can be known from the chemical composition in Table 1 that the FCV (sample 3) used in the present invention includes Mn, Sn, Cu, S, Mg, P and Fe in addition to C and Si. In these compositions, C is the main component that precipitates graphite, and the content of C required for FCV is 3.0 to 3.9%. However, if the content is less than 3.3%, the tendency of quenching (that is, the tendency to precipitate carbides) becomes large, and conversely, if the content exceeds 3.8%, ferrite is easily generated. Therefore, its practical range is 3.3 to 3.8%, and the optimal range is 3.4 to 3.6%.

If the amount of added Si is insufficient, it will have a negative effect on the stabilization of FCV and promote the chilling tendency. Conversely, if the amount of added Si is too large, the shape of graphite becomes large so that the basic structure tends to become ferrite. Therefore, its practical range is 1.5 to 3.0%, and the optimal range is 1.8 to 2.5%.

Mn is effective for stabilizing the pearlite structure; however, if it is contained in a large amount, it promotes the chilling tendency. Therefore, its preferable range is 0.2 to 0.8%.

In general, although the addition of Sn is limited, it should be noted that the addition of Sn above 0.03% has the effect of stabilizing the pearlite structure. However, if the Sn content exceeds 0.25%, the shape of graphite becomes flaky, so that the graphite shape of FCV cannot be obtained. Therefore, its preferable range is 0.03 to 0.2%.

Generally, although the addition amount of Cu is also limited, it should be noted that the addition amount of Cu not less than 0.25% will make FCV have a pearlite structure, which is also useful for increasing yield strength and toughness. However, if the Cu content exceeds 2.0%, segregation tends to occur in the structure. Therefore, its preferable range is 0.25 to 1.5%.

In the present invention, S must be added for sure. S is a component for preventing graphite spheroidization. If the S content is less than 0.01%, graphite is spheroidized, and the obtained cast iron is close to ductile iron, thereby increasing the amount of shrinkage. As a result, this shrinkage is prone to casting defects such as voids. On the contrary, if the S content exceeds 0.09%, graphite becomes flaky, so that stable FCV cannot be obtained. Therefore, its preferable range is 0.01 to 0.08%.

If the content of Mg is less than 0.005%, the graphite becomes flaky. On the contrary, if the content exceeds 0.04%, graphite becomes spherical. In both cases, casting defects such as slag inclusions occur, so the preferred range is 0.005 to 0.04%.

If the content of P exceeds 0.1%, iron phosphide (phosphide eutectic), which is a hard substance, is precipitated in the basic structure. In this case, when pulleys and the like are made of such cast iron, the wire ropes wound thereon wear prematurely. Therefore, the P content should be set at not more than 0.1%.

As described above, in the FCV used in the present invention, the pearlite structure can be stabilized at a pearlite region percentage of not less than 90%, and an FCV having excellent wear resistance can be obtained. Furthermore, the above-mentioned FCV can be obtained in a cast state, so that no treatment is required after the cast iron is solidified, and an FCV excellent in castability can be obtained.

The elevator sheave manufactured using the above-mentioned FCV will be described below with reference to accompanying drawings 2 to 5 . Generally, in an elevator device, a winching device 3 is installed in the machine room 2 at the top of the elevator passage 1 . This hoisting device makes the elevator box 9 (described later) ascend or descend. The winching device 3 includes a motor 4, a speed reducer 5 for reducing the speed of the motor 4, a pulley connected to the output shaft of the speed reducer 5, and an electromagnetic brake 7 for braking the input shaft of the speed reducer 5. The pulley 6 has a plurality of rope grooves 6G formed on its outer periphery. The wire ropes 8 each extend around the rope groove 6G. The two ends of steel wire rope 8 link to each other with elevator box 9 and the balance block 10 in elevator channel 1 li respectively. When the motor 4 rotates the pulley 6, the wire rope 8 moves by the friction force between the wire rope 8 and the rope groove 6G, thereby causing the elevator box 9 to go up or down.

In order to determine the effect of an elevator pulley made of FCV with a pearlite phase as the basic structure and a pearlite region percentage of not less than 90%, an abrasion test (life test) was performed using the test apparatus shown in FIGS. 6 and 7 . The testing device comprises two groups of horizontally spaced pulley test pieces 20a and 20b, an idler wheel 21 is located between the two sets of pulley test pieces 20a and 20b but higher than them, a drive wheel 22 and a tension adjustment wheel 23 are positioned on the pulley test piece Outboard of 20a and 20b but lower than these pulleys, the wire rope 8 is connected by a connector 24 in the form of a cordless end and extends around the pulley test pieces 20a and 20b, the idler pulley 21, the drive pulley 22 and the tension adjustment pulley 23. Two sets of pulley test pieces 20a and 20b are installed on two rotating shafts 25 respectively. One ends of the two rotating shafts 25 pass through respective bearings 26, and two sprockets 27a and 27b are respectively mounted on these ends of the two rotating shafts. The number of teeth of the sprocket 27a is slightly different from that of the sprocket 27b. A chain 28 extends around two sprockets 27a and 27b. The driving device 30 is connected to the driving wheel 22 by the driving shaft 29 , and the hydraulic device 31 is connected to the tension adjusting wheel 23 to adjust the distance between the tension adjusting wheel 23 and the driving wheel 22 .

In the test apparatus constructed as described above, the driving device 30 is repeatedly driven in the normal direction and the reverse direction, thereby moving the wire rope 8 in the directions of arrows a and b in FIG. 6 . At this time, as described above, since the number of teeth of the sprockets 27a and 27b is slightly different, the peripheral speed of the pulley sample 20a is different from that of the pulley sample 20b, and the gap between the wire rope 8 and the pulley samples 20a and 20b Slight sliding occurs, and the pulley test pieces 20a and 20b are forcibly worn. In addition to the method of making the number of teeth of the sprocket 27a and the number of teeth of the sprocket 27b different, it is also possible to use a method of making the rotational speed or outer diameter of one set of pulley test pieces different from that of the other set of pulley test pieces.

As the pulley specimens 20a and 20b, pulleys made of FCV with a pearlite phase as the basic structure and a pearlite region percentage of not less than 90%, pulleys made of FCD with a pearlite basic structure, and pulleys made of FC The completed pulleys were installed in the above-mentioned test device and comparative tests were carried out.

As an estimate of the wear of the pulley test piece, due to wear of the pulley test piece 20, the wire rope moves from position 8a shown in FIG. 8 to position 8b. The cross-sectional area 32 of the worn portion was measured as the amount of pulley wear (mm ² ). When measuring the amount of wear of the pulley, use modeling materials to make a mold according to the worn part of the pulley, and then use an enlarged scale to measure the cross-sectional area of the mold.

Fig. 9 shows the results of the above comparison test of the wear (life) of the pulley test pieces. It is clearly shown in Fig. 9 that the wear amount of the pulley made of FCV is significantly smaller than that of the pulley made of FC, and the wear resistance is basically the same as that of the FCD pulley.

Although the pearlite region percentage of FCV made of the above-mentioned pulley test piece is 95%, the test using the same pulley wear test device has confirmed that as long as the pearlite region percentage is not less than 90%, the FCV has good wear resistance. In particular, it has been determined that the wear resistance drops by 30 to 40% at a pearlite domain percentage of 80%.

It has been found that when the amount of rotation of the FCV sheaves described above is converted to the travel distance of a standard elevator at a speed of 105 m/min, the sheave life can exceed the travel distance of 56,000 kilometers. The running distance of 56,000 kilometers is equivalent to the running distance of the above-mentioned standard elevator with a running time of 120 hours per month (which has been determined by the actual operation of the elevator). And 105 m/min is the highest speed of the standard elevator. The above-mentioned running distance of 56,000 kilometers corresponds to a service life of about 7 years. Therefore the pulley of the present invention has greatly improved on the wear resistance compared with those traditional pulleys that will be replaced in 3 to 5 years.

Next, in order to determine the influence of the FCV pulley of the present invention (used on the hoisting device of the elevator) on the steel wire rope, the test device shown in Figure 10 and Figure 11 was used to carry out the life test of the steel wire rope.

In FIG. 10, the pulley test pieces 20a and 20b and the idler pulley 21 are arranged in such a way that the steel rope test piece 33 extends around it in a double S shape, so that the steel rope test piece 33 is curved. This test apparatus is substantially similar to the pulley grinding wheel test apparatus described above, except that the sprocket 28 is absent and the structure shown in FIG. 11 is absent. More specifically, FIG. 11 is a cross-sectional view taken along line C-C of FIG. 10, showing a cross-section of the pulley test piece 20a. The pulley sample 20a surrounded and extended by each wire rope 33 is rotatably supported on the shaft 25 by each individual sliding bearing 34, and the two ends of the shaft 25 are rotatably supported on the bearing 26. With this structure, a continuous bending test of the steel wire rope 33, that is, a bending fatigue failure test (life test) of the steel wire rope 33 can be performed.

As a pulley test piece, a pulley made of FCV of the present invention and a pulley made of FC were installed in the above-mentioned wire rope life testing device. A cross-section of an example wire rope test piece 33 used in conjunction with these pulleys is shown in FIG. 12 . In FIG. 12 , the steel wire rope includes a steel core 35 and a ply rope 36 . Each ply rope 36 is made up of three kinds of fine steel wires, namely outer layer steel wire 37 , middle layer steel wire 38 and core steel wire 39 .

The steel wire rope whose outer layer steel wire 37 has a tensile strength of about 135kgf/ ^mm2 is called "E type steel wire rope", and is generally used as a steel wire rope for elevators. Therefore, this wire rope was used in combination with the above-mentioned FC pulley test piece.

A steel wire rope whose outer layer steel wire 37 has a tensile strength of about 165 kgf/mm ² is called "A type steel wire rope". This steel wire rope is used in combination with the FCV pulley test piece of the present invention, and the life test of the steel wire rope is carried out.

Figure 13 shows the results of the steel wire life comparison test, in which the above two types of pulley specimens are combined with the above steel wire rope specimens for practical use respectively, and this test is carried out with the above test device. 13 shows the relationship between the number of reciprocating motions of the wire rope 33 (ie the number of times the wire rope is bent) and the damage state of the outer layer steel wire 37 in contact with the pulley (ie the number of broken steel wires 37). It is clearly shown in Fig. 13 that the damage degree of the A steel wire rope combined with the FCV pulley test piece of the present invention is greatly reduced compared with the damage degree of the E-type steel wire rope combined with the FC pulley test piece, so it can be known that the A-type steel wire rope Combined with FCV pulleys, it is suitable as a hinged device for elevators. In particular, it has been confirmed that the degree of damage to the wire ropes has been reduced by about 50%.

Type A steel wire rope whose outer layer steel wire tensile strength is about 165kgf/ ^mm2 has been described in detail, and similar tests have confirmed that the preferred hardness of the outer layer steel wire of this wire rope is Hv420 to 460.

Next, non-destructive testing of the FCV used in the present invention using ultrasonic waves will be described. We know that, in general, the passing speed of ultrasonic waves passing through cast iron is definitely related to the shape of graphite in cast iron. Therefore, after mastering the relationship between the mechanical properties of cast iron and the passing speed of ultrasonic waves, accurately applying ultrasonic waves to cast iron can classify the shape of graphite in cast iron. Ultrasonic testing was performed on the FCV used in the present invention. The test results in Fig. 14 show the relationship between the tensile strength (mechanical properties) of cast iron and the passing speed of ultrasonic waves. Pulleys made of FCV, pulleys made of FCD, and pulleys made of FC were prepared as cast iron test pieces, and the relationship between the effective strength (tensile strength) of these test pieces and the ultrasonic velocity was found. As can be clearly seen in Fig. 14, the FCV region is between the FC region and the FCD region, and it can be confirmed that the ultrasonic velocity in the FCV region is in the range of 4,800 m/s to 5,400 m/s. Similarly, when the relationship between the hardness of FCV and the ultrasonic velocity was measured, it was found that the hardness corresponding to the ultrasonic velocity of 4,800 m/s to 5,400 m/s was H _B 200 to H _B 250.

Even when a cooling rate adjustment device such as a chill iron is used to adjust the cooling rate of the FCV (comprising a hypoeutectic composition) used in the present invention during solidification, a stable pearlite structure with a different percentage of pearlite domains can be obtained. FCV of less than 90%.

Claims (1)

1. An elevator apparatus comprising a steel wire rope and a rotatable pulley, the ^steel wire rope extending around the pulley, characterized in that the steel wire rope has a hardness of Hv420 to 460 and a tensile strength of 165kgf/mm Layer steel wire, said pulley is composed of dense worm-like graphite cast iron having an ultrasonic passing speed of 4,800 to 5,400 m/s, a hardness of H _B 200 to 250, including a hypoeutectic composition and having a percentage of as-cast pearlite domains of not less than 90% production.

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