JP5458356B2 - 2-stage balanced fire pump - Google Patents

Description

  The present invention relates to a fire fighting pump that achieves a reduction in weight of a fire fighting pump and improves strength and corrosion resistance to ensure product life.

Generally, fire pumps are required to be lighter, assuming operability at the fire site and ease of transport.
However, fire pumps based on aluminum alloys are difficult to realize due to problems such as durability and wear resistance, and many fire pumps based on copper alloys are used.
Besides fire fighting pumps, pumps based on aluminum alloys are widely used. For example, Patent Document 1 discloses a vane pump using an aluminum alloy for a cylinder and a side block.

JP 2006-125328 A

However, with conventional fire fighting pumps of this type, when fire fighting pumps are manufactured using lightweight metals such as aluminum, their durability and wear resistance are problematic. For example, aluminum is used for the guide vane, the low and high pressure side cover, the water supply liner, the low and high pressure side impellers, and the preload blades that are the main parts of fire fighting pumps. Nickel chrome steel or stainless steel is used for the shaft that supports the preload blade and rotates at high speed to ensure strength and rigidity.
For this reason, corrosion is unavoidable due to a potential difference between different metals at the fitting portion between the shaft and the low / high pressure side impeller and the preload blade.
In addition, the aluminum material has a lower hardness than nickel chrome steel or stainless steel, and there is a possibility that a gap (backlash) may occur due to the secular change of the key groove in the fitting portion.
The present invention has been proposed in view of the above circumstances, and it is possible to form a ceramic coating on the surface of an impeller made of aluminum material, a preload blade, etc., to increase the surface hardness, and to prevent corrosion due to a potential difference by an insulating material. The purpose is to provide a fire fighting pump.

To achieve the above object, the present invention provides a sheet Yafuto composed of a rotatably mounted nickel-chromium steel or stainless steel two-stage balanced type fire pump body, by the key into the key groove formed on said shaft An impeller mainly composed of a fixed and rotatably supported aluminum, a cover member mainly composed of aluminum disposed around the impeller, and a radially outer periphery of the impeller A guide vane mainly made of aluminum, and the impeller has a two-stage configuration of a low-pressure side impeller and a high-pressure side impeller. The impeller is subjected to a ceramic coating treatment with a film thickness of 10 μm in an aqueous solution, and the impeller The surface coating is characterized by performing 20 μm cationic electrodeposition coating .

  Since this invention consists of an above-described structure, there can exist an effect which is demonstrated below.

In the invention according to claim 1, the present invention is key to rotatably supported by the sheet Yafuto composed of a nickel-chromium steel or stainless steel having a key groove formed in the shaft in two stages balance equation fire pump body An impeller mainly composed of an aluminum fixed and rotatably supported by, a cover member mainly composed of aluminum disposed around the impeller, and a radially outer periphery of the impeller. The impeller has a two-stage configuration of a low-pressure side impeller and a high-pressure side impeller, and the impeller is subjected to a ceramic coating treatment with a film thickness of 10 μm in an aqueous solution. Since the impeller is subjected to cationic electrodeposition coating of 20 μm as the surface coating, the surface hardness of the impeller and the preload blade is improved. Generation of play (gap) due to secular change in the key groove of the fitting portion can be prevented. In addition , the surface hardness of the impeller and the preload blade is improved, and the surface treatment film is not scraped or peeled off during assembly during manufacturing. In addition, the ceramic coating can sufficiently withstand wear during the service life of the fire pump, for example, for 18 years. Furthermore, due to the insulating properties of the ceramic coating, it is possible to prevent corrosion due to a potential difference between dissimilar metals between the impeller based on aluminum and the preload blade and the shaft. Furthermore, since the ceramic coating has an insulating property, corrosion due to a potential difference between different metals such as a shaft can be prevented.
In the present invention, since the impeller surface is coated with a cationic electrodeposition of 20 μm, it is excellent in throwing power, suitable for parts having a complicated shape like an impeller, and has a high smoothness on the surface of the coating, and machining. It has a characteristic that reflects the surface roughness of the surface .

FIG. 1 is a cross-sectional view showing an embodiment of a fire fighting pump according to the present invention. FIG. 2 is a cross-sectional view showing a gap between an impeller hole diameter and a shaft shaft diameter in the fire fighting pump. FIG. 3: is explanatory drawing which shows the procedure of the combined cycle test (CCT) by the salt water sprayer of the pump for fire fighting. FIG. 4 is a perspective view showing an impeller body used in the fire fighting pump and a test sample thereof. FIG. 5: is the side view and longitudinal cross-sectional view which cut | disconnected the sample which complete | finished the combined cycle test in the pump for fire fighting.

  The fire pump of the present invention has a ceramic film formed on the surface of impellers and preload blades made of aluminum material to increase the surface hardness and is made of an insulating material, thus preventing gaps due to aging. In addition, corrosion due to a potential difference between different metals can be prevented.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating an embodiment. FIG. 1 is a sectional view showing an embodiment of a fire fighting pump according to the present invention. Here, the fire pump 10 includes a shaft 11 rotatably supported on the pump body, a low pressure side impeller 12 mainly composed of aluminum rotatably supported by the shaft 11, and a high pressure side impeller 13. The low pressure side cover member 14 mainly made of aluminum disposed around the low pressure side impeller 12, the high pressure side cover member 15, and the aluminum disposed on the outer periphery in the radial direction of the impellers 12 and 13. Guide vanes 16 made mainly of aluminum, water supply pipe liners 17 made mainly of aluminum, and spare blades 18 made mainly of aluminum disposed in front of the low pressure side impeller 12 and the high pressure side impeller 13. And a ceramic coating 19 is formed on the surfaces of the impellers 12 and 13 and the preload blade 18.

  The shaft 11 is made of nickel chrome steel or stainless steel in order to ensure necessary strength and rigidity, and is rotatably supported on the pump body by a bearing. The pump body is configured by integrally connecting a water supply pipe liner 17, a low-pressure side cover member 14, a guide vane 16, a high-pressure side cover member 15 and the like with a plurality of bolts.

The low pressure side impeller 12 and the high pressure side impeller 13 are fixed to the shaft by a key 21 in a key groove 20 formed in the shaft 11, and the periphery thereof is surrounded by a low pressure side cover member 14, a guide vane 16, and a high pressure side cover member 15. Has been.
The preload blade 18 is also fixed to the shaft by a key 23 in a key groove 22 formed in the shaft 11, and the low pressure side cover member 14 surrounds the periphery thereof. A water supply liner 17 is connected to the side of the low-pressure side cover member 14 so that water is supplied to the pump.

  The low-pressure side impeller 12, the high-pressure side impeller 13 and the preload blade 18 are manufactured using aluminum as a main material, and a ceramic film 19 is formed on the surface to a thickness of 10 μm. Further, the ceramic coating is prepared so that the surface hardness is Hv 1000 to 1200. Furthermore, the ceramic coating has an insulating property.

Next, an endurance test method and test results of the fire pump 10 configured as described above will be described. First, as an evaluation item, 1) Is it strong enough not to damage the surface treatment when the impeller is pressed into the pump shaft?
2) Is the film thickness of the surface treatment appropriate for reaching the product life?
3) Set the allowable limit of corrosion and calculate the product life from the degree of progress of corrosion.
As shown in FIG. 2, when corrosion occurs in the impeller / pump shaft fitting portion and proceeds, the gap due to corrosion becomes loose and the impeller is detached from the central axis and causes interference with the cover. Therefore, the allowable limit of corrosion is the interference between the impeller and the cover.

  FIG. 3 is an explanatory diagram showing a procedure of a combined cycle test (CCT) using a salt sprayer of a fire fighting pump according to the present invention. Here, a combined cycle test (CCT) using a salt spray was performed. The test conditions are in accordance with JASO M609-91, and the test cycle is as follows. First, salt spray is performed for 2 hours at a temperature of 35 ° C. and a salt water concentration of 5% as shown in FIG. Next, it is dried for 4 hours under conditions of a temperature of 60 ° C. and a humidity of 30%. Subsequently, it is moistened for 2 hours under conditions of a temperature of 50 ° C. and a humidity of 95%. The above process, totaling 8 hours is defined as one cycle. This combined cycle test is a severe condition in which drying and wetting are applied to the salt spray test, and corrosion can be accelerated in a short time in a state close to exposure to the actual environment.

  Next, the corrosion measurement results and the gap expansion prediction will be described according to Table 1. Table 1 shows the measurement result of the gap between the impeller and the shaft fitting portion, and the prediction of the tendency of the gap enlargement. As shown in FIG. 5, the test sample 24 was cut in the axial direction as shown in FIG. 5, and the cut surface was observed to measure three locations of gaps T1, T2, and T3 generated by corrosion. In addition, a comparison between an example in which an impeller is alumite-treated and an example in which a ceramic coating treatment according to the present invention is carried out is shown, and a gap value at the time of fitting (fitting tolerance range) And extended in the time series direction. The time required to reach the allowable limit of the gap is 2.6 to 2.8 years (average 2.7 years) for anodizing, and 6.4 to 9.3 years (average 7.5 years) for ceramic coating. )Met.

  FIG. 4 is a perspective view showing an impeller body used for the fire fighting pump of the present invention and a test sample thereof. For the test sample 24, a part in which a shaft 26 and a key 27 were press-fitted into a boss portion 25 at the center of the impeller was prepared. A stainless steel (SUS) material having a larger potential difference with respect to aluminum was used for the shaft key 27. The impeller central part 28 is coated with two types of different surface treatments, and a shaft key is press-fitted into each. In sample 1, as the corrosion resistance / curing treatment, hard anodized was formed to a thickness of 5 to 8 μm, the hardness was set to 350 to 450 Hv, and the surface coating was a cationic electrodeposition coating having a thickness of 20 μm. In Sample 2, the ceramic coating was formed to a thickness of 10 μm as the corrosion resistance / curing treatment, the hardness was 800 to 1200 Hv, and the surface coating was a cationic electrodeposition coating having a thickness of 20 μm. This time, ceramic coating is a treatment in an aqueous solution, has excellent throwing power, is suitable for parts with complex shapes like impellers, has high smoothness on the coating surface, and reflects the surface roughness of the machined surface have.

  As shown in Table 2, the correlation between the corrosion and the actual environment reaches the clearance value set at the allowable limit in the combined cycle test, as shown in Table 2, about 2.7 years for the alumite treatment and about 7.7 for the ceramic coating treatment. Five years have passed and the product life is about 2.8 times longer than the alumite treatment. However, the combined cycle test environment is more harsh than the average fire pump usage environment, and it is not reasonable to estimate this number of years as the product life. Therefore, when the atmospheric environment of ISO standard is cited and the corrosiveness is distinguished in five stages from C1 (very small) to C5 (very large), the combined cycle test environment corresponds to C5 as shown in Table 3. I think that. The corrosion environment coefficient is 1 time for C1, 2 times for C2, 3 times for C3, 4 times for C4, and 5 times for C5. Moreover, most of the domestic corrosion classifications including coastal areas are classified as C2 (small) or C3 (normal). Most fire engines are stored indoors, and considering the state of use and maintenance, the use environment is considered to be equivalent to C2. Table 2 shows the correlation between the test results and the actual environment in terms of the expansion of the gap in the time series.

As shown in Table 2, in the case of anodizing, it was about 2.7 years in the corrosive category C5 (combined cycle test), and about 6.7 years in the corrosive category C2 (actual environment).
In the case of ceramic coating processing, the corrosiveness category C5 (combined cycle test) is about 7.5 years, the corrosiveness category C2 (actual environment) is about 18.8 years, and the life expectancy required for fire fighting pumps is 18 years. It turned out to be well tolerated.

  In addition, although the said description demonstrated the pumps for fire fighting, such as a turbine pump, it can apply to the centrifugal pump, mixed flow pump, axial flow pump, volute pump, vane pump etc. which used the aluminum material of other forms. .

DESCRIPTION OF SYMBOLS 10 Fire pump 11 Shaft 12 Low pressure side impeller 13 High pressure side impeller 14 Low pressure side cover member 15 High pressure side cover member 16 Guide vane 17 Water supply pipe liner 18 Preload blade 19 Ceramic coating 20 Key groove 21 Key 22 Key groove 23 Key 24 Test sample 25 Boss part 26 Shaft 27 Key 28 Impeller central part 29 Liner ring part

Claims (1)

A sheet Yafuto composed of a rotatably mounted nickel-chromium steel or stainless steel two-stage balanced type fire pump body,
An impeller mainly composed of an aluminum fixed to a keyway formed in the shaft by a key and supported rotatably;
A cover member mainly made of aluminum disposed around the impeller, and a guide vane mainly made of aluminum disposed on the outer periphery in the radial direction of the impeller,
The impeller has a two-stage configuration of a low pressure side impeller and a high pressure side impeller .
A two-stage balance type fire fighting pump characterized in that the impeller is subjected to a ceramic coating treatment with a film thickness of 10 μm in an aqueous solution, and a 20 μm cationic electrodeposition coating is applied to the impeller as a surface coating .

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