KR100272191B1 - Heat treatment method for rotating compressor roller - Google Patents

Abstract

PURPOSE: A method for heat treating a roller for a rotary compressor is provided to reduce manufacturing cost and improve quality of the roller by settling defects due to generation of cracks. CONSTITUTION: The method comprises the processes of preheating a roller manufactured of Mo-Ni-Cr cast iron consisting of 3.3 wt.% of C, 2.1 wt.% of Si, 0.65 wt.% of Mn, 0.3 wt.% of Ni and 0.6 wt.% of Cr and continuous casting cast iron consisting of 3.45 wt.% of C, 2.7 wt.% of Si, 0.68 wt.% of Mn, 0.39 wt.% of Cu, 0.1 wt.% of Cr and 0.11 wt.% of Mo at the temperature of 900 deg.C for 30 minutes; heating the roller under the environment that is maintained with a carbon potential of 1.3 wt.% for 90 minutes and quenching the heated roller to an oil coolant of 50 deg.C; washing the quenched roller in an alkali cleaning agent in which the temperature of 80 deg.C is maintained for 30 minutes; and manufacturing a roller having a strength of HRC 52 by tempering the seasoned roller at the temperature of 250 deg.C for 2 hours after seasoning the washed roll by leaving it alone in the air for 4 hours.

Description

Heat treatment method of roller for rotary compressor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method of a roller for a rotary compressor, and in particular, employs a seasoning process that can stabilize residual austenite generated during the heat treatment of the roller for a rotary compressor, thereby eliminating defects caused by cracking. It relates to a heat treatment method of a roller for a rotary compressor to reduce the manufacturing cost and improve the quality.

In general, rotary compressors, which are mainly used in household appliances such as refrigerators or air conditioners, have recently become lighter and smaller. In addition, in order to improve the performance of the rotary compressor and reduce the manufacturing cost, a lot of researches are being made to fundamentally improve the materials of the mechanical components constituting the rotary compressor.

Among the mechanical parts of rotary compressors, the vanes and rollers perform relative sliding motion under high loads. Therefore, the wing and the roller can be worn by contact with the counterpart rotating at high speed in a low temperature refrigerant.

Japanese Patent Application Laid-open No. 60-73082 discloses a rotary compressor made of a roller- and blade or any one of these containing ferrous alloys. Here, metal carbides and metal oxides are formed and dispersed in the tempered martensite matrix during the tempering process for producing the rollers and vanes. In addition, nitrogen is dissolved in the martensite matrix. At this time, the metal oxide functions to seal the sintered pores in order to improve the fluid tightness of the compressor.

However, as the roller and the blade are manufactured using the iron-containing sintered alloy, the compressor roller is subjected to high load. Therefore, there is a problem that the wing and the roller performing the relative sliding motion under high load are worn by the contact with the counterpart rotating at high speed.

In view of this, various materials have been proposed to provide excellent wear resistance to wings and rollers and to improve mechanical properties such as dimensional accuracy and toughness for maintaining tolerances at low temperatures. In particular, cast iron has been mainly used as a material of the roller.

Cast iron is a Fe-C alloy containing about 2.0 to 6.67% of carbon (C). The structure of cast iron is basically formed of pearlite and graphite, but the amount, thickness or cooling rate of carbon (C) and silicon (Si) It also changes greatly. If the carbon (C) equivalent is small and the cooling rate is high, the process reaction following the initial crystallization becomes white cast iron from which austenite and cementite are crystallized. In addition, when the carbon equivalent is large and the cooling rate is small, ferrite and graphite precipitate in the vacancy reaction, thereby obtaining ferrite cast iron. White cast iron is hard and brittle, and ferrite cast iron is soft but has low wear resistance. Therefore, pearlite cast iron is preferable as cast iron for general machinery.

Cast iron is superior in castability, heat resistance and machinability compared to steel. However, the tensile strength, fatigue limit and impact value are low. In order to remedy this drawback, various treatments and addition of alloying elements have been made. Moreover, alloy elements, such as nickel (Ni) and chromium (Cr), may be added in order to improve the heat resistance and corrosion resistance of cast iron.

The heat treatment process of the roller (roller heated) made of such cast iron is as follows. First, preheat for about 30 minutes to a temperature range of about 850 ~ 930 ℃ in the furnace. After that, the solution is held in the furnace for 60 to 90 minutes and then quenched in an oil refrigerant maintained at a temperature range of about 30 to 80 ° C. At this time, RX gas is used as the carrier gas and propane (C ₃ H ₈ ) gas is used as the enrichment gas, and the carbon (C) potential in the atmosphere is maintained at 1.2 to 1.5% by weight. do. Thereafter, the resultant was washed for 30 minutes at an temperature of 80 ° C. using an alkali cleaner, and then tempering was performed for 120 minutes at a temperature range of about 200 to 300 ° C.

By the way, in the case of heat treatment by the above-described method, a large amount of residual austenite is present after quenching, and this results in cracks as it is transformed into martensite during tempering, thereby producing a defective product.

The present invention has been made to solve the conventional problems as described above, an object of the present invention is to provide a heat treatment method of a roller for a rotary compressor to reduce the manufacturing cost and improve the quality by eliminating the defects caused by cracks. .

In order to achieve the above object, the present invention provides 3.0 to 3.6% by weight of carbon (C), 1.8 to 2.4% by weight of silicon (Si), 0.5 to 1.0% by weight of manganese (Mn), and 0.2 to 0.4% by weight. Mo-Ni-Cr cast iron consisting of% nickel (Ni), 0.5 to 1.0 wt% chromium (Cr), 0.16 to 0.4 wt% molybdenum (Mo), and 3.2 to 3.6 wt% carbon (C), 2.2 -2.9 wt% silicon (Si), 0.6-1.0 wt% manganese (Mn), 0.25-0.8 wt% copper (Cu), 0.01-0.2 wt% chromium (Cr), 0.07-0.2 wt% molybdenum Roller heated made of (Mo) continuous cast iron was preheated at a temperature of 870 ° C. for 30 minutes, and then heated for 90 minutes in an atmosphere maintained at 1.3% by weight of carbon potential to oil refrigerant at a temperature of 50 ° C. For rotary compressors which are quenched, washed for 30 minutes in an alkaline cleaner maintained at a temperature of 80 ° C., then left for 4 hours in the air, seasoned and then tempered at a temperature of 250 ° C. for 2 hours. It provides a method of heat-treating a multiple.

Preferably, the roller produced by the heat treatment method has a strength of HRC 52.

As described above, according to the present invention, unlike the conventional heat treatment method for a roller for a rotary compressor, the introduction of the seasoning process can completely eliminate defects caused by cracking of the product, thereby reducing manufacturing costs and improving quality. .

Hereinafter, preferred embodiments of the present invention will be described in detail.

In order to stabilize the residual austenite generated during the heat treatment process of the roller for a rotary compressor, the present invention employs a seasoning process in which it is left in the air for 4 hours or more after quenching.

<Example 1>

As the material of the roller for a rotary compressor, cast iron having a component as shown in Table 1 below is mainly used.

Table 1. Chemical Composition of Cast Iron (wt%)

Chemical composition Mo-Ni-Cr Cast Iron Continuous Casting Cast Iron Carbon (C) 3.0 to 3.6 3.2 to 3.6 Silicon (Si) 1.8 to 2.4 2.2 to 2.9 Manganese (Mn) 0.5 to 1.0 0.6 to 1.0 Nickel (Ni) 0.2 to 0.4 - Copper (Cu) - 0.25 to 0.8 Chrome (Cr) 0.5 to 1.0 0.01 to 0.2 Molybdenum (Mo) 0.16 to 0.4 0.07 to 0.2 Phosphorus (P) 0.1-0.3 0.1-0.3 Sulfur (S) 0.15 or less 0.15 or less

The heat treatment process of the roller (roller heated) made of cast iron having such a composition is as follows.

First, 3.3% by weight of carbon (C), 2.1% by weight of silicon (Si), 0.65% by weight of manganese (Mn), 0.3% by weight of nickel (Ni), 0.6% by weight of chromium (Cr), 0.25% by weight Mo-Ni-Cr cast iron consisting of molybdenum (Mo), 3.45 wt% carbon (C), 2.7 wt% silicon (Si), 0.68 wt% manganese (Mn), 0.39 wt% copper (Cu) , A roller made of 0.1 wt% chromium (Cr), 0.11 wt% molybdenum (Mo) continuous cast cast iron was preheated at a temperature of 850-930 ° C., preferably at 900 ° C. for 30 minutes, and then 1.3 weight It heats for 90 minutes in the atmosphere maintained by% carbon potential, and is quenched to 30-100 degreeC, preferably 50 degreeC oil refrigerant. And it wash | cleans for 30 minutes in the alkaline detergent maintained at the temperature of 80 degreeC. Thereafter, the mixture was left to stand in the atmosphere for 3 to 5 hours, preferably 4 hours, and then tempered at a temperature of 250 ° C. for 2 hours.

As a result, the roller for a rotary compressor produced by the present invention exhibited a sufficient hardness of HRC 52, and no cracking occurred.

As described above, according to the present invention, unlike the conventional heat treatment method, the introduction of the seasoning process can completely eliminate defects caused by cracking of the product, thereby reducing manufacturing costs and improving quality.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (1)

3.3 weight percent carbon (C), 2.1 weight percent silicon (Si), 0.65 weight percent manganese (Mn), 0.3 weight percent nickel (Ni), 0.6 weight percent chromium (Cr), 0.25 weight percent molybdenum Mo-Ni-Cr cast iron consisting of (Mo), 3.45 wt% carbon (C), 2.7 wt% silicon (Si), 0.68 wt% manganese (Mn), 0.39 wt% copper (Cu), 0.1 A roller made of continuous cast cast iron of wt% chromium (Cr) and molybdenum (Mo) of 0.11 wt% was preheated at a temperature of 900 ° C. for 30 minutes, and then heated for 90 minutes in an atmosphere maintained at 1.3 wt% of carbon potential. Quenched in an oil refrigerant at 50 ° C., washed for 30 minutes in an alkaline detergent maintained at a temperature of 80 ° C., and then left to stand in air for 4 hours for seasoning and then tempered at a temperature of 250 ° C. for 2 hours. A method of heat treatment of a roller for a rotary compressor, characterized by making a roller having a strength of HRC 52.