KR20110039410A - Metal alloy for a crane wheel and method of munufacturing the crane wheel using the alloy - Google Patents

Abstract

PURPOSE: A metal alloy for a crane wheel and a method for manufacturing a crane wheel using alloy are provided to improve the strength, abrasion resistance, and tenacity of a crane pulley. CONSTITUTION: As C 0.32-0.42w%, Si 0.15-0.35w%, Mn 0.80-1.20w%, P 0.04w% or less, S 0.04w% or less, V 0.15-0.35w%, and Fe 97.60-98.56w% are mixed and fused, alloy for a crane pulley is manufactured. The materials are melted at a temperature of 1,630±50°C, thereby making molten metal. The molten metal is injected into a casting mold at a temperature of 1,560±50°C and molds an auxiliary pulley. After the auxiliary pulley is heated in a thermal process furnace at 860±10°C and is cooled at the temperature of 550-600°C, annealing is performed. A rope groove is cut on the circumferential surface of a rim(2) of the annealed auxiliary pulley, and a flow-line is produced. The groove of the pulley is spray-quenched.

Description

Metal alloy for a crane wheel and method of munufacturing the crane wheel using the alloy}

The present invention relates to a pulley that supports and moves a rope in a crane that is used in an industrial field, and in particular, it is possible to increase the service life by reducing the wear of the rope over the pulley and to improve the wear resistance to extend the life of the pulley. It relates to a crane pulley alloy and a crane pulley using the same.

In general, cranes used to transport heavy goods in industrial sites, such as construction, lifting the goods using a plurality of ropes and pulleys.

Since the pulley for crane has to be transported in a state in which a rope supporting heavy load is caught, the pulley itself has to have high wear resistance, and the rope supported by the pulley rubs with the pulley to easily wear out. .

For this reason, the rope support pulleys of cranes are usually cast (FCD40), forged (S45C) and ordinary cast steel (SC49), SS41, etc. When forming a groove directly contacting the rope (groove), because the quenching depth is thin during high-frequency heat treatment, the surface peeling phenomenon occurs, the rope is in contact with the peeled portion there was a problem that the rope is easily broken.

In addition, the pulley for supporting a crane rope made of the conventional material as described above has a problem such that cracks are generated during use due to its brittleness.

If you look at these existing products by type,

General castings are weak to brittleness, but FCD40 (Ductile castings) is made of molten cast iron by adding Mg, Ce, Ca, etc. to be. FCD40 has a structure that is shaped like flake graphite. According to the kind of matrix, it can be classified into pearlite type and ferrite type.

However, the FCD40 has the advantage of low material cost and high coefficient of friction, but has a problem in that brittleness is strong and cracks are easily generated during use.

On the other hand, SC49 (ordinary cast steel) is difficult to cast the grooves through which the rope passes due to the fluidity problem, and there are defects such as sand bubbles and pin holes, which requires welding repair and causes cracks. In addition, there is a problem in that the cost increases because the material cost is expensive, as well as to perform a separate high frequency heat treatment.

In addition, S45C (forged steel) is a steel with a composition of 0.45% C. The material cost is high, the ratio of product weight to material weight (recovery rate) is extremely low, the processing time and manufacturing cost are high, and the metal breaker is destroyed. It is weak to brittleness and needs to be heat treated separately. In addition, since the quenching depth is not only a surface peeling phenomenon occurs, but also due to the instantaneous heating, the boundary between the heat treated portion and the unheated raw material is heated, there is a problem that peeling occurs in the heat-treated groove (groove).

The characteristics of each product can be summarized into a table as follows.

                Pros and cons comparison table by material

FCD 40 SC 46 SS 41 S 45C ingredient C: 2.5
Si:-
Mn:-
P:-
S: 0.02 C: 0.35
P: 0.040
S: 0.040 C:-
Mn:-
P: 0.050
S: 0.050 C: 0.42 ~ 0.48
Si: 0.15 ~ 0.35
Mn: 0.60 ~ 0.90
P: 0.030
S: 0.035 Characteristic -Molten cast iron
Spheroidal graphite by adding Mg, Ce and Ca.
-Used for high pressure and shows brittleness. -Good yield but bad liquidity
-Many pin hole defects and sand defects.
-It requires welding repair. Tensile strength is defined as 41 ~ 52kgf / mm but C% is not specified.
-It is easy to become abnormal tissue by carburizing with insufficient deoxidation.
-It is easy to soften on the surface of steel and is not suitable as heat treatment material. -Poor yield, long processing time, no disconnection line.
-The steel ingots are rolled or forged at a anneal ratio of 4S or higher.

Accordingly, the present invention solves the problem of the rope support pulley of the conventional general crane as described above, the wear of the rope is less, the production rate of the product can be increased by increasing the production rate compared to the input amount of the raw material, while the tension It is an object of the present invention to provide an alloy for a pulley of a crane that can increase strength and wear resistance and toughness at the same time, and a method of manufacturing a crane pulley using the alloy.

Pulley for crane of the present invention for achieving the above object is element C: 0.32 ~ 0.42w%, Si: 0.15 ~ 0.35w%, Mn: 0.80 ~ 1.20w%, P: max 0.04w%, S: max 0.04 W%, V: 0.15 ~ 0.35w%, Fe: 97.60 ~ 98.56w% by mixing to make a alloy made by melting at a temperature of 1,630 ± 50 ℃.

And the manufacturing method of the wire rope pulley for crane according to the present invention is a melting process of melting the alloy material at a temperature of 1,630 ± 50 ℃ to make molten metal, and injecting the molten metal into a mold at a temperature of 1,560 ± 50 ℃ rope After the molding process of casting a preliminary pulley having a conventional rim without forming a groove into which the rope is fitted, the preliminary pulley made through the forming process is gradually heated to 860 ± 10 ℃ in a heat treatment furnace. Cooling at a rate of 20 ° C. per hour from 550 to 600 ° C., followed by slow cooling to room temperature in air to form a spheroidized carbide to form a spheroidized carbide. Rope grooves are cut on the circumference of the rim in accordance with rope specifications in a hot rolling forming machine (M / C) equipped with a forming roller. After the forging is formed by hot forging at a temperature of 1,245 ± 30 ℃, the forged molding process forms a short flow line. After forging process, it is 840 ~ 880 ℃ for homogenizing in the austenite zone. After heating again Spray quenching by spraying the grooves of the pulley through which the rope passes through spray quenching process, and heating the grooved part of the molding cured through the quenching process to 450 ~ 500 ℃ for at least 5 hours. It consists of a tempering process that retains and tempers in the air to obtain Sorbite and Truesite.

The pulley for crane of the present invention made through the above process is superior in strength, wear resistance and toughness than the existing product, and shows excellent superiority in terms of economics due to the reduction of airborne in the production process and economic life of extending the product life.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail.

The rope support pulley of the crane according to the present invention has elements C: C0.32 to 0.42w%, Si: 0.15 to 0.35w%, Mn: 0.80 to 1.20w%, P: max 0.04w%, S: max 0.04w%, V: 0.15 ~ 0.35w%, Fe: 97.60 ~ 98.56w% by mixing and melting at a temperature of 1630 ± 50 ℃ made by alloy.

Among the elements, carbon (C) influences the change in the properties of iron, and is dissolved in austenite to form martensite through quenching, thereby causing tensile strength improvement.

Carbon combines with added vanadium and the like to form a hard carbide, and is employed in the matrix structure surrounding the carbide.

Tensile strength in the range of 0.32 ~ 0.42w% of carbon forms Min 52kg / mm². In addition, the carbon increases the hardness, the elongation and cross-sectional shrinkage of the carbon content in the above range also shows excellent mechanical properties. It also stabilizes the austenite matrix.

In addition, elemental manganese (Mn) acts as a deoxidation desulfurization agent, greatly affects the process reaction depending on the addition ratio with silicon (Si), and serves to remove dissolved oxygen in the molten metal during solidification.

Therefore, it is preferable to add more than 0.5w% of manganese, which shows an effective effect as a deoxidation desulfurization agent, and when the amount of manganese exceeds 2.0w%, there is a disadvantage that wear resistance is reduced and brittleness is promoted. desirable. It also increases quenchability, increases strength and is effective as a deoxidizer. Manganese refines the pearlite and hardens the ferrite to improve the yield strength of carbon steel. When a large amount is added, the oxide may react with the furnace material to precipitate. Therefore, manganese content is defined as 0.80 ~ 1.20w%.

The element vanadium (V) is a ferrite element that refines grains, improves toughness, increases tempering resistance, increases toughness during secondary curing, and improves creep resistance. In addition, the affinity for carbon and nitrogen is relatively strong, forming a stable composite carbide to improve the high temperature strength and breaking strength.

On the other hand, when the amount of carbon is small, the grain size becomes finer as the amount of vanadium increases, thereby stabilizing the matrix phase. If the vanadium content is higher than 2.0w%, vanadium is expensive and disadvantageously economically disadvantageous, and the metal protective film is soluble and has the disadvantage of progressing oxidation. Therefore, the content of vanadium is to be limited to 0.15 ~ 0.35w%.

In addition, silicon (Si) among the elements is effective as a deoxidizer because silicon oxide in molten steel is easily combined with manganese oxide to facilitate flotation. Since it is solid-solution in ferrite, it does not affect the mechanical properties of steel, but when it is added more than 2.0w%, toughness is lowered and plastic processing property is impaired, but silicon is added to improve fluidity and solidification by adding silicon due to the fluidity problem in forming step do. Therefore, the content of silicon is defined as 0.15 to 0.35w%.

Test data for measuring the physical properties of the specimens according to the content of the element according to the alloy of the present invention is shown in the table below.

Types of Psalms

division C (%) Si (%) Mn (%) P (%) S (%) V (%) Psalm 1 0.38 0.21 0.88 0.020 0.017 0.25 Psalm 2 0.37 0.26 0.94 0.015 0.019 0.23 Psalm 3 0.40 0.22 1.15 0.020 0.022 0.20 Psalm 4 0.39 0.25 0.93 0.018 0.024 0.24 Psalm 5 0.34 0.27 0.96 0.015 0.018 0.21 Psalm 6 0.36 0.26 0.86 0.019 0.017 0.19 Psalm 7 0.38 0.28 0.94 0.019 0.023 0.24 Psalm 8 0.37 0.24 0.89 0.021 0.018 0.21 Psalm 9 0.38 0.27 1.00 0.018 0.025 0.23 Psalm 10 0.39 0.29 0.83 0.019 0.014 0.20 Psalm 11 0.40 0.26 0.91 0.022 0.018 0.25 Psalm 12 0.37 0.31 0.98 0.018 0.016 0.21 Psalm 13 0.41 0.27 1.03 0.016 0.023 0.24 Psalm 14 0.38 0.32 1.16 0.018 0.019 0.20 Psalm 15 0.36 0.29 1.04 0.015 0.021 0.26 Psalm 16 0.39 0.33 0.95 0.023 0.018 0.22 Psalm 17 0.37 0.28 0.93 0.019 0.020 0.24 Psalm 18 0.36 0.26 1.07 0.020 0.018 0.20 Psalm 19 0.39 0.27 1.10 0.018 0.019 0.25 Psalm 20 0.37 0.29 0.90 0.017 0.021 0.22

Specimen Property Data

division YP (kgf / mm²) TS (kgf / mm²) EL (%) ROA (%) HB Psalm 1 53.2 81.8 22.4 45.8 245.0 Psalm 2 55.9 80.2 22.1 44.9 240.0 Psalm 3 57.6 79.8 21.7 43.3 238.0 Psalm 4 55.7 78.9 22.6 46.1 244.0 Psalm 5 54.9 80.3 21.8 44.8 241.0 Psalm 6 55.1 81.3 22.0 42.5 240.0 Psalm 7 56.5 80.9 21.7 46.0 243.0 Psalm 8 53.4 79.2 22.2 45.7 247.0 Psalm 9 57.4 82.1 21.8 46.3 243.0 Psalm 10 57.0 80.5 21.5 44.1 250.0 Psalm 11 57.1 81.8 22.3 45.8 242.0 Psalm 12 55.7 83.2 22.0 43.4 233.0 Psalm 13 58.9 83.5 22.3 45.1 242.0 Psalm 14 59.1 79.0 21.8 44.8 247.0 Psalm 15 59.8 80.4 21.6 46.4 245.0 Psalm 16 57.7 81.8 21.9 47.2 247.0 Psalm 17 58.2 82.2 22.5 42.6 238.0 Psalm 18 57.0 79.7 22.3 45.6 239.0 Psalm 19 59.8 80.8 21.7 44.1 233.0 Psalm 20 54.3 79.1 21.9 43.9 249.0

On the other hand, the method of manufacturing a crane pulley according to the present invention, after mixing the elements of the alloy configured as described above, and melted to a temperature of 1,630 ± 50 ℃ to make a molten metal (S1).

Then, the molten metal is put into a mold, and then a pulley of a desired size is formed by using a casting mold, and then cooled to room temperature (S2).

On the other hand, the pulley made in accordance with the present invention, as shown in Figure 2, by connecting the boss portion 1 and the rope rim 2 and the boss and the rim (2) is fitted with a rotating shaft in the center It consists of a supporting arm (3).

By the way, the pulley made according to the method of the present invention, as shown in Figure 1 is not formed in the groove (21) that the rope is caught on the rim (2), it is just filled with the portion that the groove 21 is to be formed It has a cylindrical rim structure.

In the manufacturing process of the wheel according to the present invention, the alloy is managed at a melting temperature of 1,630 ± 50 ° C., the tapping temperature is 1,590 ± 50 ° C., and the injection temperature is 1,560 ± 50 ° C. as in the general casting method.

The work is preheated to the mold in advance at about 200 to 250 ° C, and about 1630 ° C of molten metal is transferred to the preheated ladder. Casting is performed at a temperature of about 1550-1570 ° C.

The molding produced by the casting method as described above is deformed from the dendrite breakdown and casting structure to a stable matrix structure, and the spheroidization annealing is performed to break the precipitated carbide and change it into spherical shape (S3). As a result of the spheroidization annealing, about 80% of the carbide is precipitated to have toughness.

 In general, when the carbide surrounds the grain boundary, the material becomes generally weak. When the heat treatment is performed to spheroidize the carbide, the strength is maintained and the toughness is increased. In order to improve the mechanical properties such as plastic working and machinability, spheroidization of carbides is necessary. For this reason, the method of implementation is spheroidizing annealing.

 In the present invention, the preliminary pulley, which is a molding made by the above casting method, is gradually heated again to 860 ± 10 ° C., and then at a temperature of 860 ± 10 ° C. to a depth of 1 inch (inch) inside the casting for at least 1 hour. After maintaining the conditions (1 hour / inch + α), the cooling is performed at a rate of 20 ° C. per hour up to 550-600 ° C., followed by slow cooling (air cooling) to room temperature in air to form carbides. To achieve.

When the spheroidization annealing is performed through such a process, cracking may occur while the brittleness becomes weaker when heat treatment to obtain high strength is obtained, but since the spheroidized tissue does not generate cracks, toughness may be obtained.

On the other hand, as described above, the pulley made in the casting process according to the method of the present invention is a preliminary pulley formed in a shape in which the groove 21 to which the rope is caught is formed on the rim 2. It is mounted on a Hot Rolling Forming Machine equipped with a Cutting Roller and a Forming Roller, heated to 1,245 ± 30 ℃ with a flame, and then rotated by using a rotating plate. While the grooves 21 are formed by cutting the grooves 21 on the tubular rims 2 without the grooves for supporting the ropes using the cutting rollers, the grooves 21 are formed by the hot rolling forming machine. The rim 2 is hot forged (S4) in accordance with the wire rope standard to generate an rupture line. At this time, the hot forging molding temperature is operated at 1,245 ± 30 ℃ to obtain a dense forging structure.

Thus, forging molding process (S4) according to the present invention is economical, productivity is excellent, because the cutting operation for cutting the groove for the rope 21 and the forming operation for forging the groove proceeds at the same time compared to the existing casting products There is an advantage to get an excellent product. In addition, as cutting and molding are performed at the same time, the productivity is excellent and the production period can be shortened.

In addition, in the method for manufacturing a wire rope support pulley according to the present invention, by forming the boss and the arm of the pulley integrally with the rim portion, the generation of stress caused by welding the boss and the arm portion is prevented. It can be prevented fundamentally.

Then, the grooves 21 are quenched to alleviate the hardening of the pulley. The grooved pulley is heated to 450 to 500 ° C. and tempered in the air for at least 5 hours. Excellent wear resistance.

When the hot forming operation as described above is completed, homogenizing (Hormonizing) at 840 to 880 ° C as a flame, and spray quenching (Spray Quenching) is performed using a spray injector (S5).

The manufacturing process of the present invention has advantages such as cost reduction, productivity improvement, and reduction in production time due to a drastic process reduction.

In addition, economic benefits such as cost reduction can be obtained by simplifying the production equipment, and production of high quality products with a dense structure through a continuous heat treatment process, that is, a continuous process of spray quenching and tempering. This is a possible advantage.

If the spray quenching (Spray Quenching) is carried out in the above process, the water cooling end is abnormally quenched, the other end is air-cooled, so that only the required surface layer can be rapidly hardened.

On the other hand, the cooling rate is partially different according to the size of the product, the type of the transformed phase is different. The mass effect, which differs in the effect of heat treatment according to the size of the material, can be reduced by spray quenching.

In addition, the residual stress generated by heat treatment causes heat treatment cracking and fatigue fracture, but the compressive stress on the surface increases the fatigue strength of the product within the range where cracking does not occur.

Normally, residual stress due to quenching is caused by thermal stress during quenching or by stress accompanying phase transformation. When the steel is quenched, the surface is cooled before the inside, so that the product has a compressive residual stress on the outside and a tensile residual stress on the center. This is called the thermal stress residual stress distribution, and the compressive residual stress is present on the surface to increase the fatigue strength.

In addition, due to the improvement of the quenching depth, the tensile strength of the entire heat treated site is increased, the allowable load is also increased, and the structure of the arm 3 and the boss 1 requiring high toughness and the structure of the rim 2 area where wear resistance is required. You can get this different form.

After quenching as described above, tempering is used (S6), but quenched steels are not suitable for actual use due to internal hardness caused by quenching and internal stress caused by quenching. Is not.

For this reason, it is reheated at a suitable temperature below the transformation point to remove internal stresses and to form a spherical structure in which carbides are spherically dispersed on the ferrite matrix.

Such work is tempering, and steels which usually require strength and high toughness are carried out in a temperature range of 500 to 600 ° C., and tool steels that require hardness and wear resistance are performed at temperatures of about 200 ° C. In this process, the hardened groove portion 21 is tempered.

In the above description, the metal flow line refers to a flow of crystal grains in which steel grains are formed by receiving a stress such as forging or rolling from the outside. In general, the crystal of the metal is elongated in the longitudinal direction when rolling, forging, drawing or the like is performed.

1 is a perspective view and a cross-sectional view of a spare pulley made according to the process of the present invention,

2 is a perspective view and a cross-sectional view of a pulley made in accordance with the process of the present invention,

3 is a perspective view showing a process according to the method of the present invention.

Claims (2)

Element C: 0.33 to 0.42w%, Si: 0.15 to 0.35w%, Mn: 0.80 to 1.20w%, P: max 0.04w%, S: max 0.04w%, V: 0.15 to 0.35w%, Fe: 97.60 Alloy for Crane Pulleys Made by Melting ~ 98.56w% The melting process of melting the alloy material according to claim 1 to a temperature of 1,630 ± 50 ℃ to form a molten metal, and the rope is inserted into a rim on which the rope is supported by injecting the molten metal into a casting mold at a temperature of 1,560 ± 50 ℃ The molding process of forming a preliminary pulley having a conventional rim without forming a groove, and gradually heating the preliminary pulley made through the forming process to 860 ± 10 ° C. in a heat treatment furnace, and then 20 ° C. per hour to 550-600 ° C. Cooling is carried out at a constant speed, and then cooled slowly to room temperature in air to form a spheroidized annealing process to form carbides, and a preliminary pulley having undergone the annealing process, together with a cutting roller and a forming roller. The hot rolling forming machine (Hot Rolling Forming M / C) cuts the rope grooves on the circumferential surface of the rim in accordance with the rope specifications and heats the cut grooves at a temperature of 1,245 ± 30 ℃. After forging and heat back into the stage forging process of generating a ryuseon, after the forging process, the austenite (Austenite) areas 840 ~ 880 ℃ to homo age ranging (Hormonizing) in Spray quenching of grooves of pulleys through which sprays are sprayed by spraying to spray quenching, and quenching of the molded parts cured through the quenching process to 450 ~ 500 ℃ for at least 5 hours. Method of manufacturing a crane pulley consisting of a tempering process of retaining and tempering in the atmosphere to obtain sorbite and truesite

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