JPH09202935A - Compacted vermicular graphite cast iron and sliding device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compacted vermicular graphite cast iron excellent in wear resistance and castability and capable of stabilizing pearlitic structure by forming it from hypo-eutectic components and specifying the area ratio of as cast pearlite. SOLUTION: This compacted vermicular graphite cast iron (CV for short) is composed of hypo-eutectic components having, by weight ratio, 3.3-3.8% C and 1.5-3.0% Si, and the area ratio of as cast pearlite is regulated to >=90%. C is an essential component to precipitate graphite, and Si is a component necessary to stabilize CV. In order to stabilize pearlitic structure at >=90% area ratio, carbon equivalent is represented by hypo-eutectic components. In this CV, pearlitic structure is stabilized by forming a flake graphite cast iron into a composition in the hypoeutectic range and also forming the form of graphite into compacted vermicular form.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel compact
Vermicular graphite cast iron.

[0002]

2. Description of the Related Art For example, a sheave driven by winding a wire rope for suspending a car of an elevator is generally made of flake graphite cast iron (Ferrun Casting, hereinafter abbreviated as FC). This is because graphite is compatible with the wire rope due to the self-lubricating action, and is easy to process and inexpensive. The sheave has a V-shaped cross-section in the rope groove around which the wire rope is wound in order to secure a friction driving force with the wire rope, or an undercut rope for preventing the wire rope from coming into contact with the bottom of the rope groove. It has a groove. That is, the wire rope is brought into contact with the side surface of the rope groove, the contact surface pressure is increased, and the frictional force is increased. As described above, if the wedge effect between the wire rope and the rope groove is used, the frictional force is increased, but there is a problem that the wire rope accelerates the wear of the sheave and shortens the life of the sheave.

As a material having better wear resistance than the above FC, there is spheroidal graphite cast iron (Ferrum Casting Ductile, hereinafter abbreviated as FCD) in which the matrix structure is pearlite in the as-cast state (Japanese Patent Laid-Open No. 57-188645). Japanese Patent Laid-Open No. 1-12304
No. 8 bulletin). However, since the FCD has a dense structure and high hardness, it generally has the same machinability during machining as the above FC.
It is not suitable as a material for sheaves for elevators, because it is inferior to the above and the casting price is expensive.

On the other hand, mechanical properties, physical properties, machinability,
Compact Vermicular Graphite Cast Iron (Compact Vermicular Graphi) whose castability is between FC and FCD.
te, hereinafter referred to as CV) is considered (JP-A-60-24).
8864, JP 61-3866).

[0005]

The above-mentioned CV has intermediate characteristics between the above FC and FCD, but its wear resistance and castability are still low, and in addition, the safety of the pearlite structure is not sufficient. It was not fully satisfactory as a cast iron having intermediate characteristics with FCD.

One of the objects of the present invention is to obtain a compact vermicular graphite cast iron capable of improving wear resistance.

Another object of the present invention is to obtain a compact vermicular graphite cast iron having excellent castability.

Another object of the present invention is to obtain a compact vermicular graphite cast iron capable of stabilizing the pearlite structure.

[0009]

In order to achieve the above object, the present invention uses compact vermicular graphite cast iron in a weight ratio of C: 3.3 to 3.8%, Si: 1.5 to 3.0. % Of as-cast pearlite having an area ratio of 9%
It is composed of 0% or more.

In the above structure, C is an essential component for precipitating graphite, and Si is a component necessary for stabilizing the structure of CV. In addition, in order to stabilize the pearlite structure at an area ratio of 90% or more, the carbon equivalent is a hypoeutectic component. In the conventional CV, the graphite shape is made into a compact vermicular shape in the range of hypereutectic FCD component composition, whereas in the new CV, the shape of graphite is compact in the range of hypoeutectic component composition of FC. The vermicular shape was used to stabilize the pearlite structure.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A novel compact vermicula graphite cast iron (Ferrum Compact Vermicula) according to the present invention will be described below.
r, hereinafter abbreviated as FCV).

After melting with curapora, graphite spheroidizing treatment, inoculation treatment and desulfurization treatment are carried out, a molten metal having the composition of components shown in Table 1 is poured into a mold, and thereafter, it is solidified while adjusting the cooling rate with a chiller. A test piece was manufactured. The mechanical properties, the spheroidization ratio of graphite, the pearlite conversion ratio of the base structure, and the like were measured for these test pieces. In Table 1, sample N
o.1 and 2 are comparative examples, and sample No. 3 is an example according to the present invention. Then, the carbon equivalent (C +
1 / 3Si)

[0013]

[Table 1] Is more than 4.3% and is hypereutectic, while sample No. 3 is less than 4.3% hypoeutectic. Table 2 shows various measurement results of these samples 1 to 3. As can be seen from Table 2, samples No. 1 and 2, which became hypereutectic components, had pearlite conversion rates of 68% and 74%, while samples No. 3, which became a hypoeutectic component, had pearlite. The rate was increased to 94%, and the FCV became a stable pearlite structure. The metal structure of this sample No. 3 in the as-cast state is characterized by the rounded tip of flake graphite, as shown in the micrograph (magnification of 100 times) of FIG. 1, and crystallized into a nearly perfect pearlite matrix. You can see how it is going. Further, it can be seen from Table 2 that Sample No. 3 is superior in various mechanical properties (tensile strength, elongation, hardness).

[0014]

[Table 2] As can be seen from the component structure of Table 1, in the case of the FCV of the present invention (Sample No. 3), in addition to C and Si, Mn and S were added.
It has n, Cu, S, Mg, P and Fe. Of these, C is an essential component for precipitating graphite, and FCV
For that, 3.0-3.9% is required. But 3.
If it is less than 3%, the tendency of chilling (precipitation of carbide) becomes large, while if it exceeds 3.8%, ferrite tends to come out, so the range of 3.3 to 3.8% is practical, and A preferred range is 3.4 to 3.6%. When Si is added in a small amount, the stability of FCV is hindered and the tendency of chilling becomes large. On the other hand, when the addition amount is increased, the shape of graphite becomes coarse and ferrite is easily formed. Is practical, and the most preferred range is 1.8 to 2.5%.

Further, Mn is effective for stabilizing the pearlite structure, but if it is contained in a large amount, the tendency of chilling is increased, so the range of 0.2 to 0.8% is preferable.

Although the addition of Sn is generally restricted, it should be noted that the addition of 0.03% or more stabilizes the pearlite structure. However, when the content exceeds 0.25%, the graphite shape becomes flaky and F
Since CV graphite shape cannot be obtained, 0.03 to 0.2%
Is desirable.

Cu is generally limited in addition, but it is noted that the addition of 0.25% or more makes FCV a pearlite matrix and improves the yield strength and toughness. However, if it exceeds 2.0%, segregation is likely to occur in the structure, so 0.25 to 1.5% is preferable.

S is a component that inhibits spheroidization of graphite,
If it is less than 0.01%, the graphite is spheroidized and becomes close to spheroidal graphite cast iron. Then, the shrinkage becomes large, and casting defects such as cast cavities easily occur due to sink marks. On the other hand, if the content is 0.09% or more, the graphite becomes scaly, and a stable FCV cannot be obtained. Therefore, the range of 0.01 to 0.08% is preferable.

If Mg is less than 0.05%, the graphite shape becomes flake graphite, and if it exceeds 0.04%, it becomes spheroidal graphite, and casting defects such as slag bite occur. Therefore, 0.005
The range of 0.04% is desirable.

When P exceeds 0.1%, iron phosphide (steadite), which is a hard structure, is deposited in the matrix, and when a cast iron is used to form a pulley or the like, wear of the wire rope, which is a counterpart member, is accelerated. , 0.1% or less.

As described above, according to the embodiment of the present invention, the pearlite structure can be stabilized with the area ratio of 90% or more, and the FCV excellent in wear resistance can be obtained. Further, since the above FCV is obtained in an as-cast state, it is unnecessary to perform treatment after solidification, and the FCV has excellent castability.
Is obtained.

Next, the case where the elevator sheave is formed by the FCV according to the present invention will be described with reference to FIGS. In general, the elevator apparatus has a hoisting machine 3 installed in a machine room 2 formed at the top of a hoistway 1, and a hoisting machine 3 described later is moved up and down by the hoisting machine 3. The hoisting machine 3 includes an electric motor 4, a speed reducer 5 for reducing the rotation of the electric motor 4, and a sheave 6 connected to an output shaft of the speed reducer 5.
The electromagnetic brake 7 is provided for braking the input shaft of the speed reducer 5. The sheave 6 has a plurality of rope grooves 6G on its outer circumference. The wire rope 8 is wound around the rope grooves 6G, and both ends of the sheave 6 are suspended in the hoistway 1 so that the car 9 and the counterweight can be balanced. 10 are connected. Then, when the sheave 6 is rotated by the electric motor 4, the wire rope 8 is moved by the frictional force with the rope groove 6G, and the car 9 is moved up and down.

In order to verify the effect when the sheave 6 for the elevator is formed by FCV having a pearlite structure according to the present invention, a wear life test was conducted using the test apparatus shown in FIGS. 6 and 7. The test apparatus includes two sets of test sheaves 20a and 20b installed at intervals in the horizontal direction, an idle pulley 21 located in the upper middle of these two sets of test sheaves 20a and 20b, and the test sheave 20a. , 20
The drive pulley 22 and the tension adjusting pulley 23 located below the outer side of b and the test sheaves 20a and 20b, the idle pulley 21, the drive pulley 22, and the tension adjusting pulley 23 are wound around and connected endlessly by a connecting fitting 24. And a wire rope 8. The two sets of test sheaves 20a and 20b are mounted on a plurality of rotary shafts 25, respectively. One end of the rotary shaft 25 penetrates the bearing 26, and sprockets 27a and 27b having slightly different numbers of teeth are attached to the penetrating end. A chain 28 connects the sprockets 27a, 27b of the test sheaves 20a, 20b. Further, a drive device 30 is connected to the drive pulley 22 via a drive shaft 29,
A hydraulic device 31 is connected to the tension adjusting pulley 23 to adjust the distance from the drive pulley 22.

In the test apparatus having the above structure, the drive unit 30 is rotated in the normal direction and the reverse direction, and this is repeated,
The wire rope 8 travels as shown by arrows a and b in FIG. 6, but at this time, as described above, the sprockets 27a and
7b is a test sheave 20 with slightly different number of teeth.
Since the peripheral speeds of a and 20b are different, a slight slip occurs between the sample sheaves 20a and 20b and the wire rope 8, and the sample sheaves 20a and 20b are forcibly worn. Of. Incidentally, the sprocket 27a,
Instead of the number of teeth of 27b, the speed of one test sheave or the outer diameter may be changed.

The test equipment sheaves 20a, 2
As 0b, a sheave using FCV having a pearlite structure according to the present invention, a sheave using FCD having a pearlite matrix structure, and a sheave using FC were attached and a comparative test was performed.

Here, as a method of evaluating the wear amount of the test sheave, as shown in FIG. 8, the wire rope 8a is displaced to the position 8b due to the wear of the sheave 20, and the worn cross-sectional area 32 is It was decided to measure it as the sheave wear amount (mm ² ). The amount of sheave abrasion was measured by sampling a mold with a modeling compound and enlarging the cross section.

FIG. 9 shows an example of the results of the comparative test of the wear life of the above-mentioned sample sheaves carried out by the above method. As is apparent from FIG. 9, the wear amount of the sheave made of FCV according to the present invention is remarkably reduced as compared with the sheave made of FC, and the sheave of FCD has the same wear resistance.

The FCV used for the above-mentioned test sheave had a pearlite area ratio of 94%, but the pearlite area ratio was 9 based on the test results of a similar sheave abrasion tester.
If it is 0% or more, it has been found to have good wear resistance. As a specific example, it has been confirmed that the wear resistance decreases by 30 to 40% when the pearlite area ratio is 80%.

Converting the sheave made of the FCV into the traveling distance of a standard type elevator having a rated speed of 105 m / min, it has been found that it can withstand use of 56000 km or more.
The mileage of 56000 km is the mileage of the standard elevator in which the traveling time per month is 120 hours, which is obtained from the operation results, and the rated speed of 105 m / min is the fastest elevator as a standard elevator. The above-mentioned traveling distance of 56000 km corresponds to the expiration date of about 7 years, and the wear resistance is greatly improved as compared with the conventional sheave which is actually replaced in 3 to 5 years.

Next, in order to confirm the influence on the wire rope when the FCV according to the present invention is applied to the sheave of an elevator hoist, the life test of the wire rope is carried out by using the test apparatus shown in FIGS. 10 and 11. Was carried out.

In FIG. 10, the test sheaves 20a, 20
b and the idle pulley 21 are arranged so that the wire rope is wound like a double S shape, and the test wire rope 33
Bend. Each part of the test device is almost the same as that of the sheave wear test device described above, and is different from that of the sheave wear test device shown in FIG. That is, FIG. 11 corresponds to FIG.
It is CC sectional drawing which shows the cross section of the part of the test sheave 20a of this. Sample sheave 20 wound with sample wire rope 33
The a is rotatably supported by the slide bearing 34 which is independent between the shaft 25 and the shaft 25 both ends of which are rotatably supported by the bearing 26.
With this configuration, a continuous bending test of the sample wire rope 33, that is, a bending fatigue life test of the wire rope is possible.

A sheave made of FCV according to the present invention and a sheave made of FC were attached to the above wire rope life test apparatus as test sheaves. An example of the cross section of the sample wire rope 33 combined with this is shown in FIG. FIG.
In FIG. 2, 35 denotes a core rope of a wire rope, 36 denotes a strand composed of three kinds of thin wires, and this strand 36 is an outer layer wire 37, an intermediate wire 38, and a core wire 39.
Consists of

The tensile strength of the outer layer wire 37 is 135 kgf.
/ Mm ² class wire rope E type (or elevator type)
Since it is commonly used as a wire rope for elevators, we decided to combine it with the FC test sheave described above.

Similarly, the tensile strength of the outer layer wire 37 is 165 kg.
The wire rope of f / mm ² class is called Class A, but it is F of the present invention.
It was decided to carry out the life test of the wire rope in combination with the test sheave using CV.

FIG. 13 shows an example of the results of carrying out the life comparison test of the wire ropes by the combination of the test sheave and the test wire rope described above, using the above test apparatus. FIG.
3 is the number of round trips of the test equipment, that is, the test wire rope 3
3 shows the relationship between the number of bending times of No. 3 and the damage state (the number of wire breaks) of the outer layer wire 37 that comes into contact with the sheave of the sample wire rope 33. As is clear from FIG. 13, FC
Compared with the damage of the class E wire rope combined with the test sheave consisting of, the degree of damage of the class A wire rope combined with the test sheave consisting of FCV according to the present invention was significantly reduced, and the hoisting for elevators was improved. It turns out that it is suitable for machine sheaves and wire ropes. Specifically, it has been confirmed that the degree of damage is reduced by about 50%.

The above-mentioned wire rope has a tensile strength of 165 kgf / mm ^{2 of} class A, and the hardness of the outer layer wire of this wire rope is H _V 420 to 460.
It has been obtained from the similar test results that the wire rope is suitable.

Next, the nondestructive inspection of the FCV by ultrasonic waves according to the present invention will be described. Generally, it is known that the passing speed of ultrasonic waves in cast iron has a strong positive correlation with the shape of the underlying graphite. Therefore, by grasping the relationship between the mechanical properties of cast iron and the passing speed of ultrasonic waves, the graphite shape of cast iron can be classified by actually applying ultrasonic waves and measuring the ultrasonic speed. The FCV according to the present invention was also inspected by ultrasonic waves. As an example thereof, FIG. 14 shows test results showing the relationship between the tensile strength, which is the mechanical property of cast iron, and the ultrasonic wave passing speed. The casting of the sample is a sheave made of FCV according to the present invention, a sheave of FCD and an FC sheave.
The relationship between the substantial strength (tensile strength) of the sheave and the ultrasonic velocity is obtained. As is clear from FIG. 14, the FCV region according to the present invention is located between the FC region and the FCD region, and the ultrasonic velocity range in this region is 4800 m.
It turns out that it exists in / s-5400m / s. Similarly, when the relationship between the hardness of the FCV according to the present invention and the ultrasonic velocity was measured, it was found that the hardness at the ultrasonic velocity of 4800 m / s to 5400 m / s corresponds to H _B = 200 to 250.

The FCV according to the present invention described above is a CV having an as-cast pearlite matrix structure composed of a hypoeutectic component, but even a CV composed of a hypoeutectic component is heat treated after solidification, such as quenching and tempering, Alternatively, by performing normalizing, FCV having a pearlite matrix structure can be obtained. On the other hand, for the purpose of adjusting the cooling rate of the FCV composed of the hypoeutectic component during solidification, an FCV having a pearlite matrix structure can be obtained by using a cooling rate adjusting means such as a chill.

[0039]

According to the present invention, it is possible to obtain a compact vermicular graphite cast iron in which the area ratio of the pearlite matrix structure is 90% or more in the as-cast state, and is excellent in wear resistance and castability. Therefore, it is possible to obtain graphite cast iron suitable for a novel compact vermicula suitable for a sheave that drives a wire rope by winding the wire rope.

[Brief description of drawings]

FIG. 1 is a photomicrograph showing the metallographic structure of compact vermicular graphite cast iron according to the present invention.

FIG. 2 is a front view showing an elevator sheave.

[Selection diagram] Fig. 1

FIG. 3 is a partially longitudinal side view of an elevator sheave.

FIG. 4 is a schematic structural diagram showing an elevator device.

FIG. 5 is a plan view showing an elevator hoisting machine.

FIG. 6 is a structural diagram showing a sheave wear test device.

7 is an enlarged cross-sectional view taken along the line BB of FIG.

FIG. 8 is an explanatory diagram showing a worn state of the sheave.

FIG. 9 is a graph showing the relationship between the number of tests and the sheave wear amount.

FIG. 10 is a structural diagram showing a rope life test device.

11 is an enlarged cross-sectional view taken along the line CC of FIG.

FIG. 12 is an enlarged cross-sectional view showing a wire rope.

FIG. 13 is a diagram showing a rope life test result.

FIG. 14 is a diagram showing the relationship between tensile strength and sonic velocity.

[Explanation of symbols]

 6 ... Sheave, 8 ... Wire rope, 9 ... Car basket.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Nara 1070 Ichige, Ichika Katsuta-shi, Ibaraki Hitachi Co., Ltd. Mito Plant (72) Inventor Tatsuhiko Takahashi 1070 Ichige, Ichikatsu, Katsuta-shi Hitachi Co., Ltd. Mito Plant Within

Claims (14)

[Claims] 1. A compact vermicular graphite cast iron comprising a hypoeutectic component and having an as-cast pearlite area ratio of 90% or more. 2. A weight ratio of C: 3.3 to 3.8%, Si: 1.
Compact vermicular graphite cast iron characterized by being composed of a hypoeutectic component having 5 to 3.0% and having an as-cast pearlite area ratio of 90% or more. 3. A compact characterized in that an ultrasonic wave passing speed is faster than that of flake graphite cast iron and slower than that of spheroidal graphite cast iron, and that its tensile strength is higher than that of said flake graphite cast iron and lower than that of said spheroidal graphite cast iron. Vermicular graphite cast iron. 4. The ultrasonic wave passing speed is 4800-5400 m.
/ S, a hardness of H _B 200 to 250, compact vermicular graphite cast iron. 5. A weight ratio of C: 3.3 to 3.8%, Si: 1.
5 to 3.0%, S: 0.01 to 0.08%, Mg: 0.00
Compact vermicular graphite cast iron characterized by being composed of a hypoeutectic component having 5 to 0.04% and P: 0.1% or less and having an as-cast pearlite area ratio of 90% or more. 6. A weight ratio of C: 3.3 to 3.8%, Si: 1.
5 to 3.0%, Cu: 0.25 to 1.5%, Sn: 0.03
Compact vermicular graphite cast iron characterized by being composed of a hypoeutectic component having .about.0.2% and P: 0.1% or less and having an as-cast pearlite area ratio of 90% or more. 7. A weight ratio of C: 3.3 to 3.8%, Si: 1.
5 to 3.0%, Mn: 0.2 to 0.8%, P: 0.1% or less, S: 0.03 to 0.2%, Cu: 0.25 to 1.5%,
Sn: 0.01 to 0.08%, Mg: 0.005 to 0.04
%, The balance consisting of Fe and a eutectic component having unavoidable impurities, and an as-cast pearlite area ratio of 90% or more, compact vermicular graphite cast iron. 8. A first step of obtaining a compact vermicular graphite cast iron composed of a hypoeutectic component, and a heat treatment of the compact vermicular graphite cast iron obtained by the first step to obtain a pearlite area ratio of 90% or more. A method for producing compact vermicular graphite cast iron including a second step. 9. The method for producing compact vermicular graphite cast iron according to claim 8, wherein the heat treatment is quenching and tempering. 10. An area ratio of 90 is obtained by casting a molten metal which is a hypoeutectic component, solidifying and cooling the molten metal by using a cooling adjusting means, and then casting.
% Or more pearlite matrix structure is obtained, a method for producing compact vermicular graphite cast iron. 11. A pair of shaft-supported test sheaves, an idle pulley located between the test sheaves, the pair of test sheaves and a wire rope wound around the idle pulley, and the wire rope. An apparatus for testing wear of sheaves, comprising: a wire rope driving device that drives the wire rope; and a speed difference generating unit that causes a difference in peripheral speed between the pair of test sheaves. 12. A sliding device formed by sliding a second member with respect to a first member, wherein at least one of the first and second members has a flake graphite cast iron with an ultrasonic wave passing speed. A sliding device formed of compact vermicular graphite cast iron that is faster than spheroidal graphite cast iron and has a tensile strength greater than the flake graphite cast iron and smaller than the spheroidal graphite cast iron. 13. A power transmission device for transmitting power by bringing a first member and a second member into contact with each other, wherein at least one of the first and second members has an ultrasonic wave passing speed 1. A power transmission device formed of compact vermicular graphite cast iron that is faster than spheroidal graphite cast iron and slower than spheroidal graphite cast iron, and has a tensile strength greater than the flake graphite cast iron and smaller than the spheroidal graphite cast iron. 14. A compact vermicular graphite cast iron characterized by comprising a hypoeutectic component and having a pearlite area ratio of 90% or more.