JPH0238638B2 - KINZOKUKAKOYUNOFUHAIBOSHIHOHO - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for preventing spoilage of metal working oil, and more specifically, a method for efficiently heat-treating metal working oil to prevent the emulsion of the working oil from being destroyed and to almost increase the temperature of the working oil in a storage tank. and how to prevent corruption. Water-soluble metalworking oils such as cutting oils contain water as well as oil as nutrients and organic substances such as surfactants.Moreover, they come into contact with air during use and provide appropriate heat when cutting metal. , the conditions for microorganisms to grow are in place. Therefore, metalworking oil is easily perishable and requires appropriate management. There is a method of heating metal working oil to prevent it from spoiling, for example, as described in British Patent No.
In No. 1365332, cutting oil that has begun to rot is introduced from a storage tank into a heating device, where it is heated, cooled in a cooler, and then passed through a homogenizer to homogenize the emulsion that is about to separate. It is disclosed that it will be provided.
However, according to this method, the temperature of the cutting oil becomes high, which causes adverse effects such as damage to the material to be cut and the generation of rust, as well as loss of emulsion stability. Therefore, it is essential to use a cooler, homogenizer, etc. Furthermore, according to JP-A-55-102694, a method is adopted in which the metal working oil is heated to 65°C to sterilize microorganisms such as anaerobic bacteria, and then the scum on the top surface is separately removed. However, this method is also undesirable because the metalworking oil is heated to 65° C. or higher, which causes loss of emulsion stability. An object of the present invention is to provide a method for preventing corrosion of metal working oil, which eliminates the above-mentioned drawbacks. The present invention involves a continuous or This is a method for preventing spoilage of metal working oil, characterized in that heat treatment is carried out discontinuously and repeatedly so that the entire amount of metal working oil in a storage tank is heated once every 3 to 20 hours. Metal processing oil such as cutting oil is stored in a storage tank 1 as shown in FIG. Afterwards, it is returned to the storage tank 1 via piping 4 after being processed. As mentioned above, metal processing oil is prone to putrefaction, and if left unattended, it will generate a bad odor and have an unfavorable effect on the working environment. Appropriate sterilization treatment is carried out. Various methods are known for measuring the number of viable microorganisms, and any method can be applied to the present invention. Various criteria can be used to determine when metalworking oil has begun to deteriorate, but the inventor has determined that it should be determined when the number of aerobic bacteria in metalworking oil reaches 1 x 10 ⁷ cells/ml. did. It is desirable to continue the heat treatment according to the present invention until the number of bacteria becomes 1×10 ⁶ cells/ml or less. In the heat treatment according to the present invention, a part of the metal working oil was extracted from the storage tank 1, sent to the heating device 7 through the pipe 5 and the pump 6, and heated at a temperature of 48 to 60°C for 30 seconds to 8 minutes by heat exchange. Afterwards, it is returned to the storage tank 1 via piping 8. It is desirable that the heating time be as short as possible, for example 60
As a guideline, the time should be 30 to 90 seconds when the temperature is 50°C, and 5 to 8 minutes when the temperature is 50°C. In addition, the cycle in which the entire amount of metal working oil in the storage tank 1 is heat treated is
Repeat the cycle continuously or discontinuously for 20 hours, preferably 5 to 15 hours, and confirm that the number of aerobic bacteria in the metalworking oil is 1 x 10 ⁶ cells/ml or less as described above. After that, the heat treatment is finished. After a predetermined period of time, if signs of putrefaction appear due to growth of microorganisms, heat treatment is performed again to prevent putrefaction of the metal working oil. According to the present invention, it is possible to prevent spoilage without destroying the emulsion of the metal working oil, and the temperature of the metal working oil in the storage tank hardly rises even when heat treatment is performed, thereby causing problems that were previously experienced. does not occur at all. In addition, the present invention does not use disinfectants that are harmful to the human body, so it does not deteriorate the working environment, and it is not selective in the type of microorganisms that it sterilizes. It is effective against Next, examples of the present invention will be shown. Example Cutting oil 200, which is an emulsion-type cutting oil (50 times diluted liquid) with 0.5% of a sample of rotten cutting oil added, was put into a storage tank and used for machining work for 7 days without taking any sterilization measures. What I started was acknowledged. Therefore, the cutting oil was extracted from the storage tank at a flow rate of 330 ml/min and led to a heating device via piping. This device brought the samples into contact with hot water at 60°C via piping, where they were exposed to heat for 60 seconds and then returned to the storage tank. It took 10 hours to heat treat all the cutting oil in the storage tank. This treatment was continued continuously, and the number of viable microorganisms in the cutting oil in the storage tank was measured at regular intervals by an agar culture method. Note that the temperature of the cutting oil in the storage tank increased by 1.7 to 2.0°C due to the heat treatment. The measurement results are shown in Table 1.

[Table] Test example 5 ml of emulsion-type cutting oil (30 times diluted liquid) was placed in a small test tube and heated at temperatures of 50°C, 60°C, and 70°C for a specified period of time to determine whether or not there was oil separation on the surface layer and the pH. We investigated the changes. The results are shown in Table 2.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a flow sheet of an embodiment of the method of the present invention. 1... Storage tank, 2, 4, 5, 8... Piping,
3, 6...Pump, 7...Heating device.

Claims (1)

[Claims] 1. A process consisting of extracting a part of the metal working oil from a metal working oil storage tank, heating it at a temperature of 48 to 60°C for 30 seconds to 8 minutes by heat exchange, and then returning it to the storage tank. Repeatedly or discontinuously, the total amount of metalworking oil in the storage tank is
A method for preventing spoilage of metal working oil, characterized in that it is heat treated once every 20 hours. 2. The method according to claim 1, wherein the heat treatment of the metal processing oil is started when the number of aerobic bacteria in the processing oil reaches 1 x 10 ⁷ cells/ml.