JPS6347957B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a mouthpiece for a hydraulic oil hose. Conventionally, mineral oil-based oils have been used as hydraulic fluids, and their applications are mainly related to hydraulic control, with working pressures as high as 70 to 200 atmospheres, and mineral oils themselves are flammable. The equipment required sufficient consideration to prevent leakage. However, from the point of view of preventing danger, it is desirable that the hydraulic fluid be flame-retardant, and for this reason, as a result of research into various types of hydraulic fluids such as phosphate ester and emulsion-type hydraulic fluids, flame-retardant Water/glycol (50:50) is increasingly being used as a synthetic hydraulic fluid. On the other hand, it is well known that flexible hoses are often used in hydraulic control devices and the like that use hydraulic fluid for convenience of handling. However, the hose is equipped with a carbon steel hose cap at its tip for connection to the piping system. Because this type of hose is often exposed to the atmosphere during storage before assembling hydraulic control equipment, conventionally the carbon steel cap was treated with galvanized colored chromate (zinc chromate treatment) to prevent rust. things were being used. When using hydraulic fluid with a hose equipped with the zinc-plated, colored chromate-treated nozzle, there was no problem with conventional mineral oil-based hydraulic fluid, but when using water/glycol-based hydraulic fluid, In this case, various problems such as deterioration of the hydraulic oil, generation of sludge, and poor rust prevention of the mouthpiece were found to occur. The present inventors studied the cause and came to the following conclusion. (1) It is thought that a zinc-plated colored chromate-treated hose cap reacts with water and glycol-based hydraulic fluid to produce a black sticky substance (Zn soap sludge). For this reason, sealing defects (poor thread accuracy, hose coming off, etc.) may occur at the mouthpiece, and the generated sludge flows through the hydraulic pipes, causing damage to various equipment (solenoid valves, relief valves, flow valves, etc.). This may cause malfunction of control valves, etc.). (2) Accelerates deterioration of hydraulic oil due to the above chemical reaction. (3) Once the cap has been used for a certain period of time (especially the inner part), the galvanized colored chromate treatment layer has completely disappeared due to the above reaction, so it cannot be expected to have a rust-preventing effect during long-term storage. . FIG. 1 shows a cap attached to a hose, where 1 is the cap, 2 is a hose, and 3 is a tightening fitting attached to the end of the hose. In the case of zinc plating treated with colored chromate, there may be problems such as a decrease in the accuracy of the thread 4, the hose coming off from the hose attachment part 5, a seal failure at the part 6, and sludge from the inside part 7 of the mouthpiece. This generation accelerates the deterioration of hydraulic fluid. The present invention solves the above problems and does not generate sludge even when using water/glycol based hydraulic oil.
This provides a hose fitting for hydraulic fluid that is highly durable and does not cause poor sealing of the hose or damage to various devices of the hydraulic control system. The hydraulic fluid hose cap of the present invention has a coating layer that does not react with water or glycol-based hydraulic fluid by blackening the surface of the steel cap (the shape is not particularly limited) (forming a triiron tetroxide film). was formed. This black dyeing treatment is a simple and low-cost treatment using inexpensive materials, so it does not cause chemical reactions with water or glycol-based hydraulic fluids like the conventional galvanized colored chromate treatment, and it is long-lasting. It is extremely effective in preventing rust during storage. Black dyeing is a surface treatment method aimed at making steel heat-resistant and rust-preventing. An oxidizing agent is mixed with a concentrated aqueous solution of caustic soda to blacken the surface of the steel at a temperature range of 130°C to 150°C. It is something.
As the oxidizing agent to be added, sodium nitrite, soda cyanide, sodium phosphate, lead oxide, sodium thiosulfate, etc. are used. Hereinafter, the superiority of the hydraulic fluid hose cap according to the present invention will be explained in comparison with a conventional galvanized colored chromate treated (zinc chromate treated) cap using a immersion test. In the immersion test, (1) Zinc chromate treated caps and black dyed caps were used as test pieces. (2) As the liquid for the immersion test, both ethylene glycol type and propylene glycol type water/glycol hydraulic fluids were used. (3) The test method is to first wash the test piece thoroughly with petroleum ether, dry it, and then place it in a 350ml glass bottle.
The bottle was sealed. This bottle was placed in a constant temperature bath at 70°C for 30 days, and the occurrence of sludge and changes in the properties of the test liquid were observed. The test results were as shown in Tables 1 and 2.

[Table] In Table 1, Zn and Fe in the liquid were measured by atomic absorption spectrometry.

[Table] In the measurements shown in Table 2, the appearance was determined by visual inspection. Viscosity is expressed in CSt at 40℃, based on JIS K2283 (Petroleum products kinematic viscosity and viscosity test method), preliminary alkalinity is based on JIS K2234 (Preliminary alkalinity test method for antifreeze liquid), and froth is expressed in ml-ml. It is indicated by
This is a value measured based on JIS K2518 (petroleum product foaming test method). As is clear from the table above, with the conventional zinc chromate treatment nozzle, sludge was already generated 6 days after the start of the test, and after 30 days, the amount of Zn dissolved in the liquid was 30 ppm for the propylene type and 56 ppm for the ethylene type. On the other hand, in the case of the black-dyed nozzle according to the present invention, only a small amount of Fe was dissolved in the liquid even after 30 days of testing, and no sludge was generated. It can be seen that chemical reactions with water and glycol-based hydraulic fluids are extremely rare. Furthermore, looking at the changes in the properties of the sample liquid after the number of days of immersion, in the case of the Zn chromate-treated nozzle, the foaming rate was very high, indicating a large change in properties, whereas in the case of the sample liquid of the present invention, In the case of the cap, there is almost no difference from the new solution. As described above, when using the hydraulic oil hose fitting according to the present invention, unlike conventional galvanized colored chromate treated fittings, there is no chemical reaction with water or glycol-based hydraulic oil, and there is no rust prevention effect. This is sufficient to prevent malfunctions in the hydraulic system and deterioration of the hydraulic fluid, and to prevent rust during long-term storage. As a result, hydraulic control using water/glycol-based hydraulic fluid at high pressure can fully function, which brings extremely high industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the mouthpiece installed on a hose. 1...Bag, 2...Hose, 3...Tightening fitting.

Claims (1)

[Scope of Claims] 1. A hydraulic control system using water/glycol hydraulic fluid, characterized in that a steel cap connected to a hose is coated with a protective film formed by blackening treatment. Oil hose cap.