JPH0713514B2 - Crankshaft for rotary compressor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft for a compressor, and more particularly to a crankshaft of a rotary compressor for a heat pump, which has good productivity and excellent wear resistance.

[Background of the Invention]

Generally, a method using a heat pump has been favored as a safe and comfortable heating, and recently, the amount of CFC used as a heat carrier substance has been increasing for the purpose of energy saving. For this reason, the oil in the compressor was diluted with liquid freon, and its sliding parts, especially the crankshaft, came to be operated under extremely severe conditions. As a countermeasure against this, an expensive bearing material such as a sintered alloy or carbon has been used, and an expensive material such as a hardened material or cast alloy alloy, which is difficult to process, has to be used for the crankshaft.

[Object of the Invention]

An object of the present invention is to provide an inexpensive rotary compressor crankshaft having excellent wear resistance without using these expensive bearing materials and without using hard materials that are difficult to process.

[Outline of Invention]

Sulphonitriding is a surface treatment method developed in France and is a very effective means of applying it to the surface of sliding parts under severe operating conditions. However, the processing temperature is 600 ℃
Due to the high temperature close to, the material containing the stress inherent in the material and the phase including the phase that changes around this temperature is distorted by the treatment, and cannot be applied to high precision parts such as the crankshaft of a rotary compressor.

On the other hand, in the manufacturing process of ferrite cast fine graphite cast iron by die casting, the melted and held molten metal is rapidly cooled in the die during solidification, so that the finely divided graphite forms a mass, and the annealing step Since the carbide is decomposed into ferrite and surrounds the graphite group, it has high strength and excellent workability, and is used as a part of a rotary compressor that requires high-precision processing. Further, the inventors have used this cast iron as the crankshaft of the present compressor because it has excellent wear resistance despite the fact that it is a ferrite material, but it has been used as a crankshaft of a rotary compressor. There was a difficulty in using it under the conditions.

Therefore, the inventor has variously improved the sliding characteristics of the ferrite fine graphite cast iron having this excellent workability,
This material is completely annealed and has a very small internal stress. Also, even if a slight internal stress generated by roughing is removed by strain relief annealing, it is hardly deformed even if it is subjected to the sulphidic nitriding treatment. I found a thing.

By subjecting the ferrite fine graphite cast iron having almost no internal stress to the sulphidizing and nitriding treatment as described above, it is possible to manufacture a crankshaft for a compressor having excellent workability and excellent wear resistance.

Next, the reason for setting the strength and the thickness of the nitrosulfurized layer will be described. For a crankshaft of a rotary compressor, it is required to have a strength of 25 kg / mm ² or more, and if it is less than this strength, the various features of fine graphite cast iron are lost, so 25 kg / m 2
Specified as m ² or more. If the thickness of the sulphurization chamber treatment layer is 4 μm or more, sufficient life characteristics cannot be obtained, and if it is 20 μm or more, the variation in dimensional change becomes large and it cannot be used as the crankshaft of a rotary compressor. 4μm ~ 20μ
It was defined as m.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings and Table 1.

The figure shows that the ferrite fine graphite cast iron and ordinary cast iron crankshafts are roughly machined, strain relief annealing is performed at 600 ° C for 2 hours, and after finishing machining, 520 to 570 ° C for 0.5 hour is subjected to sulfuritriding treatment for approximately 5 hours.
This is data obtained by measuring the straightness of a product having a μm compound layer. Straight cast iron crankshaft straightness 4.5 × 10 ^-5
In contrast to the following, the ferrite fine graphite cast iron crankshaft has a very high accuracy of 1.5 × 10 ^-5 or less and can be used sufficiently as the crankshaft of a rotary compressor. In addition, a compressor using this crankshaft is used with a dilution ratio of 90% (liquid CFC 90
Table 1 shows the results of a two-week harsh test in a lubricating oil of 10 parts of oil. Crankshafts that have been subjected to nitrocarburizing treatment in this way exhibit extremely superior wear resistance compared to conventional combinations of materials. According to the present embodiment, there is an effect that a rotary compressor using an inexpensive material having good workability can be operated with high efficiency under severe conditions.

[Advantages of the Invention] As described above, according to the present invention, it is possible to perform highly precise sulphididitriding treatment with less deformation on a crankshaft made of ferrite fine graphite cast iron with good workability, and to significantly improve this wear resistance. Since it can be improved, there is an effect that an efficient rotary compressor can be manufactured at low cost.

[Brief description of drawings]

The figure is a graph showing the accuracy of a crankshaft that has been subjected to nitrosulfurization treatment.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical indication location F04B 35/01 39/00 103 A 7618-3H (72) Inventor Iizuka Todai 800 Oita Tomita, Ohira-machi, Shimotsuga-gun, Tochigi Prefecture Stock company Hitachi Co., Ltd.Tochigi factory (72) Inventor Kazushi Fukuda 800, Odaira-cho, Shimotsuga-gun, Tochigi Tomita 800 Co., Ltd. Tochigi Plant (72) Inventor Eiichi Takeuchi 785, Funashita, Minowa-cho, Kohoku-ku, Yokohama-shi, Kanagawa Inside Tokyo Heat Treatment Industry Co., Ltd. (72) Toshio Abe Funakashi, Minowa-cho, Yokohama-shi, Kanagawa Seventy-fiveth Street, Tokyo Heat Treatment Industry Co., Ltd. (72) Inventor Masaaki Sahara, Seventy-five, Funashita, Minowa-cho, Kohoku-ku, Yokohama-shi, Kanagawa

Claims (1)

[Claims] 1. A compound layer having a tensile strength of 25 kg / mm ² or more obtained by die casting or the like and having a tensile strength of 25 kg / mm ² or more, and a compound layer of 4 to 20 μm that is subjected to a nitrosulfurization treatment on the surface. Characteristic crankshaft for rotary compressor.