JP4033282B2 - Purification method of aqueous liquid for metal processing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aqueous liquid for metal working that is a water-diluted solution of an emulsion-type or soluble-type water-soluble cutting fluid used in metalworking processes such as cutting and grinding in a machine factory, etc. Further, the present invention relates to a method for purifying metal powders such as cutting and grinding, and cutting oil that is a processing oil such as mineral oil.
[0002]
[Prior art]
In the cutting and grinding processes in machine factories and the like, an aqueous liquid for metal processing containing cutting oil (processing oil) is provided to provide each function such as wetting, cooling, lubrication and corrosion prevention during cutting and grinding. used. As this aqueous processing liquid, an emulsion type (containing mineral oil, surfactant, etc.) and a soluble type (containing oil, surfactant, etc.) are known. Emulsion-type cutting fluid is milky white when diluted with water to make an aqueous solution for metal processing, while soluble type cutting fluid is translucent when diluted with water to make an aqueous solution for metalworking. It will be. After using this processing aqueous liquid, the liquid contains cutting oil, machine oil such as hydraulic oil / lubricating oil, and cutting, ground metal powder (debris) and the like.
[0003]
Therefore, in order to reuse the metal working aqueous liquid, it is necessary to perform a purification treatment. Conventionally, such a used aqueous solution for metal processing is stored in a dirty tank, the metal powder is precipitated and removed, filtered through a filter to remove residues, and contaminants such as metal powder are removed. It was. However, such a purification method cannot remove fine metal powder. That is, if the filter is made finer, fine metal powder can be removed, but there is a problem that clogging is likely to occur and the purification efficiency is significantly reduced.
[0004]
Japanese Patent Laid-Open No. 7-328888 discloses a method for removing fine metal powder by applying centrifugal force to the metal working fluid using a centrifugal separator in order to remove the fine metal powder. For example, it is described that a metal powder having a particle size of about 5 to 10 μm or more can be removed by applying a centrifugal force of 300 to 800 G. However, with this method, it is difficult to remove ultrafine metal powder of less than 5 μm.
[0005]
As a method for removing impurities such as fine metal powder using a centrifugal separator, a method using oil-water separation or solid-liquid separation with a high centrifugal force of 2000 to 10,000 G is also known. This can be used when the aqueous solution for metalworking is a solution type using a soluble oil, but there is a problem that the micelle is destroyed in the case of a micelle type emulsion type or a soluble type.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to remove fine metal powder having a particle size of 5 μm or less contained in an aqueous metal working liquid used for metal working such as metal cutting and grinding. An object of the present invention is to provide a method for purifying an aqueous liquid for micelle-containing emulsion-type metal processing that does not deteriorate the characteristics.
[0007]
[Means for Solving the Problems]
The present invention is a method for purifying an aqueous liquid for metal working containing micellar cutting oil containing metal powder generated by metal processing such as metal cutting and grinding, the metal containing the metal powder A first step of removing a part of the metal powder from the aqueous processing liquid by precipitation, on the liquid surface of the aqueous metal processing liquid, a part of the remaining metal powder is made into micelles contained in the aqueous liquid. A second step of floating together with a portion of the oil that is not present and removing the floated material; and a third step of removing a portion of the remaining metal powder by filtering the aqueous metal working liquid from which the metal powder has been removed. A replenishment oil is added to the purified metal working aqueous liquid in advance or in any of the steps of the first purification stage, and the oil content in the aqueous liquid containing the replenishment oil is Adjust the amount of non-micellar oil to 0.5% by mass or more. Below, the aqueous solution was introduced into a centrifugal separator, a second purification step removed together with encompassing oil which metal powder ultrafine particle size of less than 20μm by the centrifugal force of 800～1200G; metals including and It exists in the purification processing method of the aqueous liquid for a process.
[0008]
The above-mentioned cutting oil is a processing oil component for imparting functions such as wetting, cooling, lubrication, and anticorrosion during metal processing such as cutting and grinding. Mineral oil (mineral oil), fats and fatty acids It consists of at least one selected from. The emulsion type cutting fluid containing cutting oil has mineral oil as an essential component as cutting oil, and the soluble type cutting fluid has oil and fat as essential components as cutting oil. In addition, the term “oil” in the present invention means all other oils such as the cutting oil, the replenishing oil, and the machine oil.
[0009]
The above method of the present invention is generally carried out continuously.
[0010]
In the purification treatment method, the amount of oil that has not been micellized in the second purification stage is preferably 0.5 to 2% by mass. Further, the centrifugal force of the centrifugal separator in the second purification stage is preferably 800~1000G especially. This centrifugal force is generally set in a range in which the micelles are not decomposed according to the binding force of the micelles in the aqueous metal working liquid. Furthermore, the aqueous liquid for metal processing after completion of the second purification stage contains 5 to 35% by mass of a surfactant based on the non-volatile content after removal of the solid content such as metal powder of this liquid (when using an emulsion type). Is preferably 15 to 30% by mass, and preferably 5 to 20% by mass when a soluble type is used. In the second purification stage, the metal powder having a particle diameter of less than 20 μm is removed by centrifugal force. In the present invention, even ultrafine metal powder having a particle diameter of less than 5 μm is removed. The metal working aqueous solution is usually used by diluting a commercially available cutting fluid with water. The content of the cutting fluid at that time, that is, the non-volatile content is preferably 1 to 10% by mass, particularly 2 to 5% by mass. % Is preferred. In addition, the replenishment oil is added immediately before the metalworking aqueous solution is introduced into the centrifuge. It is preferable to add.
[0011]
In the present invention, the replenishing oil may be the same mineral oil, fat or the like as the cutting oil, or may be different. The replenishing oil is preferably a mineral oil different from the cutting oil. That is, the replenishment oil is preferably higher in affinity with the metal than the cutting oil. In the present invention, the metal generally contains at least a light metal such as an aluminum alloy.
[0012]
The present invention also provides a replenishing oil in a method for purifying a metal working aqueous liquid that removes metal powder from a metal working aqueous liquid containing a micellized cutting oil containing metal powder generated by metal processing. The amount of oil in the aqueous liquid containing the replenished oil is adjusted to 0.5% by mass or more, and under this condition, the aqueous liquid is introduced into a centrifuge. There is also a purification processing method for an aqueous liquid for metal processing, comprising a purification step of removing ultrafine metal powder having a particle diameter of less than 20 μm together with oil containing the powder by centrifugal force of 800 to 1200 G.
[0013]
Also in the above method, the above-described preferred embodiment can be applied.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is an emulsion type or a soluble type (a lot of water-soluble components such as alkanolamine compared to the emulsion type) used in metal working processes such as cutting and grinding in machine factories. After removing the rough metal powder from the metal processing aqueous liquid (containing the used cutting oil consisting of cutting and grinding metal powder, cutting oil, etc. in the water), add replenishment oil, and the micelles in the liquid It is characterized by removing fine metal powder of less than 20 μm, particularly less than 5 μm, with a relatively low centrifugal force (generally 800 to 1500 G) under the condition of containing 0.5% by mass or more of free oil that has not been converted into a solid.
[0015]
The purification treatment method of the present invention can be performed, for example, as follows. This will be described with reference to FIGS.
[0016]
FIG. 1 shows an example of an apparatus for performing the purification treatment method of the present invention. Emulsion type metal working aqueous liquid (including metal powder by cutting and grinding, free oil (usually flotation oil) etc.) discharged from TRM (cutting line consisting of transfer machine etc.) is dirty tank (precipitation) It is fed to a separation tank 1. Replenishment oil that is difficult to be micelle is usually added to the trough 13 below the TRM from the oil replenishing device 12 and sent to the dirty tank. In the dirty tank, coarse metal powder having a particle size of 50 μm or more is generally precipitated and removed (first step). In this step, for example, as shown in FIG. 2, a scraper conveyor is installed at the bottom of the tank, and the metal powder that continuously settles can be removed. The precipitate contains not only metal powder but also other impurities such as cutting machine dust.
[0017]
The oil skimmer tank 2 arranged next to the dirty tank 1 and on the opposite side of the primary filtration tank 3 is connected to the dirty tank 1 by a pipe 2a, and the floating oil (mainly containing fat and oil and containing impurities) is oil. It is removed by a schema or the like (second step). The oil schema tank 2 may be provided between the dirty tank 1 and the primary filtration tank. In this step, for example, as shown in FIG. 3 (i), a resin plate disk having a magnet on the surface rotates while immersing the lower part in the surface of the liquid, so that floating oil or the like adhering to the surface is collected by a scraper. To be removed. Alternatively, as shown in (ii), the belt may be rotated and collected. Usually, floating oil sludge is filled into drums.
[0018]
The floating oil is mainly derived from oil adhering to a machine or the like, supplementary oil or the like, but cutting oil (particularly mineral oil) may also be included. These usually contain metal powder, but are lighter than water, so the amount and particle size of the metal powder are small. In general, floating oil contains not only metal powder but also a large amount of impurities.
[0019]
The above-mentioned coarse metal powder and aqueous metal processing liquid from which floating oil has been removed are fed to the primary filter tank 3 through the pipe 3a, filtered through a filter, and mainly have a particle size of 20 μm or more (preferably less than 50 μm). The metal powder is removed (third step). This filtration step is performed, for example, by introducing a processing aqueous liquid onto the filter as shown in FIG. The filtrate is fed to the primary clean tank 4 through the pipe 4a and stored. Generally, the filter is # 80 to 100 (80 to 100 mesh). A part of the processing liquid may be supplied from the primary clean tank 4 to the processing point of the TRM.
[0020]
Furthermore, in order to raise the precision of filtration, a filtration process is performed again. Therefore, the third step, that is, the primary filter tank 3 and the primary clean tank 4 may be omitted. The filtered aqueous solution for metal processing is fed to the secondary filter tank 5 through the pipe 5a and filtered through a filter. Generally, metal powder having a particle size of 20 μm or more (preferably less than 50 μm) is mainly removed. (Re-third step). The filtrate is fed to the secondary clean tank 6 through the pipe 6a. Generally, the filter is # 100 to 120 (100 to 120 mesh). A part of the processing liquid may be supplied from the secondary clean tank 5 to the TRM for cleaning the workpiece seating surface.
[0021]
The secondary clean tank 6 has a configuration shown in FIGS. 5 and 6, for example. As shown in FIG. 5, the filtrate from the secondary filter tank 5 is fed to the secondary clean tank 6 through a pipe 6a. A part of the fed metal processing aqueous liquid (filtrate) is sent from the pipe 11a to the oil content measuring device (oil-in-liquid particle counter) 11 and the oil content on the TRM shown in FIG. 6 (see FIG. 1). A signal related to the oil amount is transmitted to the electromagnetic valve 12b of the replenishing device 12 via the wiring 11b. In accordance with this signal (that is, the oil amount in the specified liquid is reached), an appropriate amount of replenishment oil to be replenished is fed from the oil replenishing device 12 of FIG. 6 through the pipe 12a. The replenishment oil is fed to the dirty tank 1 via the trough 13 below the TRM. The replenishing oil is selected according to the cutting fluid used and the intended use, and is generally preferably an oil that is compatible with the metal powder, but it may be mineral oil, fat or fatty acid constituting the cutting oil, or other oil. The first to third steps correspond to the first processing stage of the present invention.
[0022]
Next, the second processing step, which is a characteristic part of the present invention, is performed as follows, for example.
[0023]
The metal working aqueous solution (filtrate) fed through the pipe 6a is fed to the low speed centrifuge 7 for continuously removing oil (free oil) through the pipe 7a. The metal powder of less than 20 μm is removed together with the oil containing it (free oil, mainly replenishing oil and cutting oil) (second purification stage). In the aqueous metal working liquid processed in the centrifuge 7, 0.5% by mass or more of oil such as replenishing oil that is not micellar floats in the liquid (this is caused by the oil content measuring device and the oil replenishing device). In the centrifuge, and a metal powder having a particle size of less than 20 μm (especially less than 5 μm) with a centrifugal force of 800-1500 G (preferably 800-1200 G, especially 800-1000 G) Oil, which may contain a fine powder of In the present invention, the presence of the oil component containing the replenishment oil and the specific centrifugal force enables particularly fine metal powder having a particle size of less than 5 μm to be removed together with the oil component such as a replenishment oil containing the oil. Have sex.
[0024]
The oil containing the metal powder and the like removed by the centrifuge 7 is sent to the disposal drum through the pipe 7c. Further, the metal working aqueous liquid from which the metal powder or the like has been removed is returned to the secondary clean tank 6 through the pipe 7b. The metal working aqueous solution processed by the centrifuge is supplied to the TRM by the pump 14 via the pipe 6b. In general, the centrifuge 7 does not need to be operated continuously, and is operated according to the contamination state of the aqueous metal working liquid.
[0025]
In addition, the metal powder etc. which were removed with each filter, such as the metal powder which precipitated in the said dirty tank, are sent to the conveyor 10, a water | moisture content is removed, and it removes from a hopper.
[0026]
An object to be processed by the centrifuge, which is a characteristic part of the present invention, will be described with reference to FIG.
[0027]
In FIG. 7, states of the metal powder, the floating oil, the floating oil, and the like contained in the emulsion-type metal processing aqueous liquid fed from the TRM are depicted as enlarged schematic views. Floating oil 71 floats on the liquid surface, as described above, and the emulsion constitutes micelle 72, which is cutting oil 74 (may include other oils) as shown in the figure. Has a structure encompassed by the surfactant 73. On the other hand, the floating oil 75 contains fine metal powder (mainly less than 5 μm, particularly less than 1 μm), and has no or almost no surfactant. The thing (deteriorated micelle) 76 in which the surfactant 73 partially adheres to the floating oil 75 ′ also contains the same metal powder. There are independent fine metal powders 78, and those having a particle diameter of 5 to 10 [mu] m are mainly used when the first to third steps are completed. In the centrifuge, floating oil other than micelles, metal powder, and the like are removed, and a well-purified aqueous liquid for emulsion-type metal processing, which is substantially only micelles, is obtained. In addition, the metal powder described above contains not only metal powder but also impurities other than metal powder.
[0028]
As described above, in the present invention, there is an appropriate amount of oil containing replenishment oil, which mainly contains fine metal powder to become floating oil, and in combination with a specific centrifugal force, fine particles that are a feature of the present invention. The metal powder can be removed.
[0029]
As the centrifuge, for example, a liquid separator as shown in FIG. 8 can be used. This can be obtained from CINC, for example. The metal working aqueous liquid is introduced from the inflow ports 81a and 81b, stirred in the stirring zone 82, and fed into the rotor 84 through the rotary blade 83 at the bottom. Inside the rotor, the aqueous working liquid is pushed upward by the principle of an automatic pump, and separation is started inside the rotor by the action of centrifugal force. The aqueous metal working liquid purified by the specific gravity discharge port 85a is discharged, and the oil containing fine metal powder and the like is discharged in liquid form from the low specific gravity discharge port 85b. 86 is a rotor insertion slot, 87 is a cavity, 88 is a separation blade, and 89 is a centrifugal disk.
[0030]
The aqueous metal working solution used by diluting the emulsion type or soluble type cutting fluid used in the method of the present invention with water can be separated by the following method so that it can be separated (especially by a centrifuge). It has a configuration. That is, an aqueous liquid for metal processing in which cutting oil is formed into micelles with a surfactant. For example, the micelles are not destroyed by a low centrifugal force of 800 to 1500 G, and the micelles are destroyed by a high centrifugal force of 2000 G or more. . In the case of separation with a centrifugal force of 800 to 1500 G, the oil can be recovered without breaking the micelles, and when it is desired to purify the grinding oil in the micelles, for example, the cutting oil can be separated and removed with a high centrifugal force of 2000 G or more. By performing the process of removing only the cutting oil, the metal working aqueous liquid can be recovered even by adding only the cutting oil.
[0031]
The composition of the emulsion-type cutting fluid used in the aqueous metal working liquid is, for example, 50-80% by mass of mineral oil, 0-30% by mass of fats and fatty acids, 0-30% by mass of extreme pressure agent, and 15-15 of surfactant. 35 mass%, alkanolamine and inorganic alkali 0-5 mass%, organic inhibitor 0-5 mass%, preservative 2 mass% or less, nonferrous metal anticorrosive 1 mass% or less, antifoaming agent 1 mass% or less, water 0 Consists of 10% by mass.
[0032]
The composition of the soluble cutting fluid used in the aqueous metal working liquid is, for example, 0-30% by weight of mineral oil, 5-30% by weight of fats and fatty acids, 0-20% by weight of extreme pressure agent, and 5-5 of surfactant. 25 mass%, alkanolamine and inorganic alkali 10-40 mass%, organic inhibitor 5-10 mass%, inorganic inhibitor 0-10 mass%, preservative 2 mass% or less, nonferrous metal anticorrosive 1 mass% or less, antifoaming agent It consists of 1 mass% or less and water 5-40 mass%.
[0033]
As said mineral oil, a thing with low affinity with a metal is preferable, for example, spindle oil and dynamo oil can be mentioned. As fats and oils and fatty acids, those having a low affinity for metals are preferable. For example, synthetic esters and the like can be mentioned in consideration of anti-corrosion properties. As the surfactant, synthetic is preferable, and polyalkylene glycol can be exemplified.
[0034]
In the present invention, replenishment oil is added to capture fine metal powder. It is necessary to use oil that is difficult to form micelles as the replenishment oil. As the replenishing oil, those having high affinity with metals and being resistant to spoilage are preferable, and are generally selected from mineral oils and synthetic oils and fats in consideration of viscosity.
[0035]
【The invention's effect】
By using the method of the present invention, the fine metal powder having a particle size of 5 μm or less in the emulsion-type or soluble-type metal working aqueous solution treated in the first purification stage can be removed, and the growth of microorganisms can be achieved. And the deterioration and reduction of the cutting oil component can be suppressed. Furthermore, at that time, since the liquid characteristics of the ionic state of the aqueous liquid for processing are not deteriorated, the aqueous liquid for metal processing can be used for a long period of time, and the replacement time can be greatly delayed compared to the conventional case. it can.
[0036]
In addition, the metal working aqueous liquid can be recovered even by adding only the cutting oil by performing the step of removing only the cutting oil by using the centrifugal separator at a high centrifugal force.
[Brief description of the drawings]
FIG. 1 is an example of an apparatus for performing a purification treatment method of the present invention.
FIG. 2 is a detailed view of an example of the dirty tank of FIG.
3 (i) and (ii) are detailed views of an example of the oil skimmer tank of FIG. 1, respectively.
4 is a detailed view of an example of the filter tank of FIG.
FIG. 5 is a detailed view of the secondary clean tank of FIG. 1 and its surroundings.
6 is a diagram of the oil replenishment device of FIG. 1 and its surroundings. FIG.
FIG. 7 is an enlarged schematic view of states of metal powder, floating oil, floating oil, and the like contained in an aqueous liquid for emulsion-type metal processing fed from TRM.
FIG. 8 is a detailed view of an example of the centrifuge of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dirty tank 2 Oil skimmer tank 3 Primary filter tank 3a, 4a, 5a, 6a, 6b, 7a, 7b, 7c, 11a Pipe 4 Primary clean tank 5 Secondary filter tank 6 Secondary clean tank 7 Centrifuge 10 Conveyor 11 Oil content measuring device 11b Wiring 12 Oil content replenishing device 12b Solenoid valve 13 Trough 14 Pump 71 Floating oil 72 Micelle 74 Cutting oil 73 Surfactant 75 Floating oil 76 Deteriorated micelle 78 Independent fine metal powder 81a, 81b Inlet 82 Stirring zone 83 Rotating blade 84 at the bottom Rotor 84a Gravity discharge port 85b Low specific gravity discharge port 86 Rotor insertion port 87 Cavity 88 Separation blade 89 Centrifugal disk

Claims (9)

A method for purifying a metal working aqueous liquid containing micellar cutting oil containing metal powder generated by metal processing, wherein a part of the metal powder is removed from the metal working aqueous liquid containing the metal powder. First step of removing by precipitation, a part of the remaining metal powder is floated together with a part of the non-micellar oil contained in the aqueous liquid on the surface of the metal processing aqueous liquid, And a first purification step including a third step of removing a part of the remaining metal powder by filtering the metal working aqueous liquid from which the metal powder has been removed; The replenishment oil is added to the aqueous liquid in advance or in any of the steps of the first purification stage, and the amount of the oil in the aqueous liquid containing the replenishment oil that is not micellized is reduced to 0. 0. Adjust to 5% by mass or more, and under this condition, add the aqueous liquid to the centrifuge. Input, and a second purification step removed together with encompassing oil which metal powder ultrafine particle size of less than 20μm by the centrifugal force of 800～1200G; and purification treatment method metalworking aqueous solution containing.   The purification process method according to claim 1, wherein the second purification step is performed under a condition in which the non-micellar oil is present in the liquid in an amount of 0.5 to 2% by mass. The purification treatment according to claim 1 or 2 , wherein the aqueous metal working liquid after the completion of the second purification stage contains 5 to 35 mass% of a surfactant with respect to the nonvolatile content after the solid content of the liquid is removed. Method. The purification method according to any one of claims 1 to 3 , wherein in the second purification step, ultrafine metal powder having a particle size of less than 5 µm is removed. Just prior to introducing the metalworking aqueous liquid in a centrifugal separator, measuring the oil amount that is not within the micelles of oil, adding the addition of the replenishment oil according to the value in the metalworking aqueous solution of the first step according Item 5. The purification treatment method according to any one of Items 1 to 4 . A replenishment oil is added in a purification method of a metal working aqueous liquid that removes metal powder from an aqueous metal working liquid containing micellar cutting oil containing metal powder generated by metal processing. The amount of non-micellar oil in the aqueous liquid containing oil is adjusted to 0.5% by mass or more, and under this condition, the aqueous liquid is introduced into a centrifuge. A purification method for an aqueous liquid for metal processing, comprising a purification step of removing ultrafine metal powder having a particle diameter of less than 20 μm together with oil containing the powder by centrifugal force. The purification treatment method according to claim 6 , which is carried out under a condition in which an oil component that has not been micellized is present in the liquid in an amount of 0.5 to 2% by mass. The aqueous processing liquid for metal processing after completion | finish of a purification | cleaning process is a purification processing method of Claim 6 or 7 containing 5-35 mass% surfactant with respect to the non volatile matter after solid content removal of this liquid. The purification method according to any one of claims 6 to 8 , wherein in the purification step, ultrafine metal powder having a particle size of less than 5 µm is removed.

Images