The object of the invention is an apparatus as defined in the preamble of claim 1 and a method as defined in the preamble of claim 10 for handling process fluid.

The apparatus and method according to the invention, hereinafter more concisely the solution according to the invention, is a solution applicable to cleaning machining fluids to be used in machine tools for machining with chip removal in the engineering & metal industry and also applicable to the maintenance and measurement of the properties of such machining fluids, which can be installed e.g. in connection with CNC machines. The solution according to the invention can also be used in other industrial sectors in which process fluid is used. The solution according to the invention can operate fully automatically as a continuous process, or as a unit to be transferred from one machine to another.

The solution according to the invention can be used for cleaning essentially all process fluids and for adjusting their concentrations. The solution is very well suited to handling machining fluids and advantageously for handling the machining fluids to be used in machining metals, e.g. for adjusting a concentration for cleaning.

For the sake of simplicity, in the context of this application the solution according to the invention is presented in more detail only in conjunction with handling machining fluid for metals, but the process fluid being referred to can just as well be a fluid for some other purpose .

Machining fluids in the machining with chip removal of metals, which are commonly also called cutting fluids or cutting coolants, are used, inter alia, to cool the workpiece and machine tool used, lubricate the process surface, protect the workpiece and machine tool from corrosion, improve chip management, and remove metal particles from the machining interface.

Machining fluids can be divided into four basic types, namely; cutting oils, emulsion-based machining fluids, semisynthetic, and synthetic machining fluids. The most widely used in industry are emulsion-based machining fluids. The solution according to the present invention is suited for cleaning all machining fluids and also for cleaning other fluids, although in this context the main focus is only on emulsion-based machining fluids.

Emulsion-based machining fluids are often mixtures of oil and water, to which various additives could have been added to improve e.g. the service life, thermal capacity, lubrication ability of the machining fluid or to prevent the amount of corrosion targeting machining devices or machining workpieces. Emulsion-based machining fluids are in most cases delivered as a concentrate to be mixed with water with a mixing ratio of e.g. 1/10-1/20. In this case, the concentration of the concentrate part in the mixed machining fluid, i.e. more concisely the concentration, is 10%-5%. One drawback of emulsion-based machining fluids is that various microflora easily form in them, and the microflora quickly impair the service life of the machining fluid and finally make the machining fluid completely unfit for service. In addition to this, microflora cause odor nuisances and also occupational health hazards and illnesses for machine tool users, such as e.g. skin allergies and respiratory disorders. The contamination of machining fluids makes it necessary to replace them relatively often. Replacement of each machining fluid incurs, inter alia, the following costs and detriments: procurement of new machining fluid, interruption to production, worktime spent on replacement, disposal of contaminated machining fluid as hazardous waste, environmental impact of non-renewable fuel used for disposal.

The microflora of machining fluids containing water use the organic compounds of the machining fluids as their nutrition and growth medium. Attempts can be made to prevent and control the formation of microflora in machining fluids by adding biocides to the machining fluid mix, which biocides are various disinfection agents, pesticides and industrial protective agents and preservatives. Biocides are, however, toxic chemicals that cause, inter alia, allergic reactions, respiratory disorders and also other illnesses for users of machine tools. In addition to this, most biocides disrupt the operation of a biological wastewater treatment plant, if large quantities of them find their way into a sewer, and they also otherwise interfere with the biological waste handling of biodegradable machining fluids. According to what is known in the art, the concentration of machining fluids is measured in most cases with a manually- operated optical refractometer, with which the concentrations of substances dissolved in the machining fluid are measured. The use of a manually-operated refractometer is, however, unreliable because the machining fluid easily makes the prism of the refractometer dirty, in which case the results given by the device are unreliable or even incorrect. Furthermore, manual measurement is inaccurate, laborious and time-consuming.

During machining, harmful oils, not belonging to the machining fluid but originating from the machine tools and workpieces being machined, hereinafter more concisely leakage oils, mix into the machining fluid, which leakage oils are generally environmentally-harmful, mineral-based oils that change the chemical properties of machining fluids, in which case the machining fluids no longer function in the desired manner. Leakage oils also burn and attach to the blades of the machine tool, resulting in breakage of the cutting blades. Leakage oils also collect small particles and other dirt on their surfaces and thus offer a good breeding ground for harmful microbes. Leakage oils are removed e.g. with various oil skimmers, however these require separate apparatuses that increase both complexity and costs. Furthermore, oil skimmers only act to remove oils on the surface, and do not remove oils mixed into machining fluid, which are even more detrimental to the blades of machine tools. When machining metals, various solid particles, e.g. metal particles and shavings, always get into the machining fluid. Some of these solid particles settle to the bottom of the machining fluid reservoir while some circulate along with the machining fluid in the machining system. These solid particles impair the surface quality of the workpiece and might cause wear, or even breakage, of the machine and cutting fluid system, particularly of blade bits, pumps, rails and bearings.

According to what is known in the art, a full circulation system based on continuous cleaning is generally used for cleaning machining fluids, the system comprising a separate cleaning device, such as a microfilter, by means of which it is endeavored to filter e.g. solid particles and leakage oils from the machining fluid that has come from a machining device. Solutions based on full circulation comprise many large, complex and expensive devices, which often handle only individual tasks, not a full process, and also take up expensive floor space. In addition, the devices require many different maintenance procedures.

Also known in the art is a method based on batch cleaning, wherein the machining fluid is transferred to a separate batch cleaning process in which the machining fluid is cleaned and later returned back into circulation. A problem with batch cleaning is that the machining fluid to be cleaned must be transferred completely out of the machining fluid system to separate cleaning, in which case completely new machining fluids need to be added to the machining fluid system. In such a case the machine tools are unused during the fluid change. In addition, changing machining fluids always incurs additional costs. Another problem is that batch cleaning is one-off cleaning, in which case the fluid starts gathering dirt again immediately after cleaning, and therefore is not continuously clean in any phase except commissioning.

According to what is known in the art, settling tanks connected to the machining system are also widely used, in which tanks the solid particles in machining fluid settle to the bottom of the reservoir, and particles that are lighter than the machining fluid, such as oils, rise to the surface of the machining fluid, from where they are skimmed off e.g. by means of oil skimmers. These types of solutions do not, however, remove leakage oils dissolved in the machining fluid, nor the smallest solid particles which remain in the machining fluid and cause wear of machine tool parts and expensive cutting blades. In addition, machining fluid sitting in reservoir tanks is an excellent breeding ground for microbes, which shorten the service life of machining fluids. Another drawback is that settling tanks often require a lot of space and comprise complex reservoir solutions that, with their various compartments, hamper cleaning and increase manufacturing costs. Separation devices based on centrifugal force, such as centrifuges and hydrocyclones, are also in use. Small particles always remain in the machining fluid, however, when using centrifuges. In addition, degradation of the emulsion has been observed in the case of emulsion-based machining fluids. Hydrocyclones are suited only for separating very small particles, so the device is not suited e.g. for the shavings mainly produced in machining metals. Another problem with separating devices based on centrifugal force is that they are not suited for all machining. These devices have significant challenges in removing e.g. the extremely fine metal dust produced when grinding cast iron.

UVC light, which effectively destroys the microbes in machining fluid, has also been used for the destruction of microbes in machining fluid. The main problem has been that UV lamps get dirty very quickly because the UV lamps have been in the cleaning fluid, or immediately above the fluid, without protective structures. Often a brittle fused silica sleeve, which breaks easily, is used as protection of the lamps. Dirt accretion also significantly weakens the efficiency of the radiation eliminating microbes. One further problem is that in solutions known in the art the surface area of the fluid used in UV filtering is generally very small, in which case the UV radiation is not sufficient for destroying all the microbes and cleaning is slow.

The aim of the present invention is to eliminate the aforementioned drawbacks and to provide an inexpensive, simple, reliable and cost-efficient apparatus and method for handling process fluid, such as machining fluid. The apparatus according to the invention is characterized by what is disclosed in the characterization part of claim 1. Correspondingly, the method according to the invention is characterized by what is disclosed in the characterization part of claim 10. Other embodiments of the invention are characterized by what is disclosed in the other claims. For implementing its purpose, the apparatus according to the invention for handling process fluid, such as machining fluid, comprises a fluid inlet, a filtering unit, a microbe elimination unit provided with one or more radiation sources transmitting radiation destroying microbes, such as UVC radiation, and a fluid outlet as well as a control & adjustment system for the functions of the apparatus. The apparatus preferably comprises a measuring unit connected to the control & adjustment system of the apparatus for measuring and adjusting the properties of the process fluid being conducted through the apparatus.

The method according to the invention can be implemented in the apparatus according to the invention. In this case solid particles and leakage oils are removed from the process fluid to be cleaned, such as machining fluid, taken into the apparatus by conducting the fluid through the filtering unit. After this, the maintenance and monitoring of the fluid and the predictability of the service life of the fluid are measured from the process fluid as well as the essential values as regards the condition and the concentration of the process fluid. After the measuring functions, the surface area of the process fluid exposed to radiation destroying microbes is expanded for elimination of the microbes, and radiation, such as UVC radiation, destroying microbes is directed at the expanded surface area of the fluid for destroying the microbes in the process fluid. Finally, the cleaned process fluid is removed from the apparatus.

One advantage of the solution according to the invention is that the solution lengthens the service life of machining fluids by cleaning them of all impurities, such as solid particles and leakage oils, by eliminating microbes and by adjusting the concentration of the machining fluids and the optimal settings for maintenance fully automatically. In this case manual, and possibly unreliable, measurement according to prior art becomes unnecessary. In this case also the need to replace the machining fluid is reduced and the need for toxic biocide additives is eliminated. Furthermore, the occupational health hazards and environmental hazards caused by machining fluids and biocides are reduced. Since machining fluid per se is classified as hazardous waste, environmental problems decrease through a reduction in the changes needed and through more opportunities to use eco-friendlier fluids.

Owing to the automation, one advantage is that the measuring interval for machining fluids becomes sufficiently frequent, and it also enables the real-time maintenance, reliable measurement and accurate documentation of the measurement results of machining fluids. In this case the machining fluid circulating in the system is constantly acceptably clean for process use. Automation also reduces the amount of work needed for maintenance of the machining fluid.

One significant advantage is that, owing to automatic measurements performed with precise and versatile measuring sensors, the physical and chemical properties, concentration and amount of microbes can be inspected and adjusted continuously and essentially in real-time. In this case e.g. the precise measuring of concentration avoids e.g. foaming of the machining fluid and the problems caused by that, and at the same time it is possible to control the amount of machining fluid to be added to the circulation of the system so that e.g. the machining fluid reservoir is not overfilled. It can be verified by means of precise temperature measuring whether the temperature of the machining fluid is at the optimal level so that the machining properties of the machining fluid do not suffer. This is particularly important in precise machining in which the effect of thermal expansion plays an important role.

Another advantage of the solution according to the invention is that the apparatus according to the invention can be controlled either locally or by means of a remote connection, and that the apparatus conveys to the user real-time information about the properties, chemical composition, amount and flow velocity of the machining fluid and also about the amount of microbes in the machining fluid.

Yet another advantage is that the radiation sources transmitting UVC radiation are not in contact with the machining fluid, in which case they do net get dirty, so consequently their radiant power remains maximal. Furthermore, the UVC radiation can be brought to bear on the large surface area of the machining fluid, in which case elimination of the microbes is as effective and rapid as possible. It is also an advantage that the radiant power of the UVC radiation and the low velocity of the machining fluid can be adjusted in real-time during the cleaning process, in which case the amount of energy to be used for cleaning can always be kept at the optimum level. Another advantage of the apparatus according to the invention is that the simple structure of the apparatus, which can be assembled from modules, enables easy movability of the device to new locations, and scalability to new size classes, and that the apparatus is customizable to the needs of the user. Another advantage is that the modules can be delivered for servicing and back to the customer as postal packages, in which case logistics costs are low.

In the following, the invention will be described in more detail by the aid of one example of its embodiments with reference to the simplified and diagrammatic drawings attached, wherein

Fig. 1 presents a diagrammatic and simplified view of one handling apparatus of machining fluid according to the invention, Fig. 2 presents a diagrammatic and simplified side view of one handling apparatus of machining fluid according to the invention, and its main components,

Fig. 3 presents a simplified view of the top part of the apparatus according to Fig. 2, as viewed perpendicularly from above with the cover of the apparatus opened,

Fig. 4 presents a diagrammatic and simplified side view of the top part of the apparatus according to Fig. 2, when sectioned, with the cover detached above the apparatus, Fig. 5 presents a diagrammatic, simplified and sectioned side view of the top part according to one embodiment of the apparatus according to Fig. 2, with the cover detached above the apparatus, and Fig. 6 presents a diagrammatic and simplified view of the data transmission arrangement of a handling apparatus according to the invention for machining fluid . Figs. 1-3 present one handling apparatus 1 according to the invention for machining fluid, more concisely maintenance apparatus 1, or even more concisely apparatus 1. In Fig. 1 the apparatus is presented diagrammatically and in Fig. 2 as viewed from the side. Fig. 3 presents the top part of a maintenance apparatus 1 as viewed directly from above, with the cover 9a of the apparatus opened, and Fig. 4 a simplified and sectioned direct side view of it with the cover 9a raised directly upwards and detached from the maintenance apparatus 1 itself.

The maintenance apparatus 1 comprises a supportive frame part, itself resting on its bedplate, onto the support of which frame part the components of the maintenance apparatus 1 are fastened. The maintenance apparatus 1 supported by the frame part comprises, inter alia, an inlet 2 for the machining fluid to be cleaned, an outlet 3 for the cleaned machining fluid, and between them a flow channel 2a for machining fluid, a pump unit 5, with suction pump 6a and high-pressure pump 6b, connected to the inlet 2, one or more filtering units 7 with filtering means 7a, and also a measuring unit 8 and an elimination unit 9 for microbes in the machining fluid. Preferably the filtering means 7a are filter inserts intended for the purpose.

The maintenance apparatus 1 also comprises an intermediate inlet 4 for clean machining fluid, with actuators such as a dosing valve and possible pump, intended to increase the concentration of the machining fluid. Preferably the machining fluid to be added is mixed with the machining fluid concentrate into emulsion in connection with the intermediate inlet 4. The water to be mixed can also be purified before bringing it into the maintenance apparatus 1 and mixing it with the machining fluid concentrate. The purification can be performed e.g. with reverse osmosis filtration, with a separate carbon filter or in some other corresponding manner. The purification is performed preferably with a water purification unit to be connected modularly to the apparatus as and when needed.

Additionally, the maintenance apparatus 1 comprises a data processing unit 10 with conventional peripherals, more concisely a computer 10, and a, preferably wireless, transmitter/receiver 11 connected to it. There is also a control & adjustment system of the maintenance apparatus 1 in the computer 10.

At least the pumps 6a and 6b of the inlet end of the maintenance apparatus 1, the measuring unit 8 with its actuators, the microbe elimination unit 9 with its actuators, and the intermediate inlet 4 with its actuators are connected to the computer 10 and/or to the control & adjustment system of the maintenance apparatus 1. The suction pump 6a is arranged to suck the machining fluid to be cleaned via the inlet 2 into the maintenance device 1 for handling. Preferably the outlet of the suction pump 6a is connected to the inlet of the high-pressure pump 6b, which high-pressure pump 6b is arranged to raise the pressure of the machining fluid to be cleaned to be so high that the machining fluid is able to flow through all the filtering means 7a of the filtering unit 7 of the maintenance apparatus and after them to the measuring unit 8 and onwards to the microbe elimination unit 9 and after that onwards, e.g. by gravity, or alternatively pumped, back to the machine tool or machining fluid reservoir via the outlet 3. Preferably the high-pressure pump 6b is a pump with adjustable pressure, in which the pressure can be adjusted to e.g. between 0.5-10 bar.

The filtering unit 7 connected to the outlet of the high- pressure pump 6b is after the high-pressure pump 6b in the flow direction of the machining fluid to be cleaned, which pump 6b pushes by means of pressure the machining fluid through all the filtering means 7a of the filtering unit 7. Preferably there are more than one filtering means 7a connected in series with one another. Preferably the filter of the first filtering means of the series is the coarsest and filters the largest particles out of the machining fluid flow. The filter of the second filtering means of the series is the second most coarse, et cetera, and finally the filter of the last filtering means of the series is the finest of all. The filtering unit 7 can comprise e.g. six filtering means 7a connected consecutively in series. The filtering means 7a can also be connected in parallel, e.g. two parallel sets of three filtering means connected in series. The filtering means 7a of the filtering unit 7 are easily and quickly replaceable, owing to the modularity of the maintenance apparatus 1, according to the properties of the machining fluid and/or the cleaning requirement. The filtering means 7a are preferably fastened to the apparatus 1 with quick-connect couplings or corresponding coupling, in which case their replacement is rapid and easy. Owing to the modularity, the apparatus 1 can be quickly and easily configured for the desired machining fluid or according to the contamination requirements for machining fluids in different operating sites. More than one filtering unit 7 can be installed in the maintenance apparatus 1. In the case of more than one filter unit 7, the filter units can be installed in parallel or in series, thus providing either increased handling speed of the maintenance apparatus 1 or improved filtering capacity. Filter units 7 installed in parallel are similar to each other, but individual filtering means 7a installed in series, of course, become denser as the machining fluid travels through the filter units.

If necessary, according to the operating site requirements, filtering means 7a can be used in the apparatus 1 also without a microbe elimination unit 9. Such an example worth mentioning is e.g. the use of microemulsion fluid as a machining fluid, in which case the microbe elimination unit 9 causes an undesired reaction in the machining fluid by gradually making macroemulsion fluid from the microemulsion fluid. In that case it is advantageous to clean the machining fluid by adding fine filtering to the series of filtering means 7a in such a way that the precision of filtering is increased with denser filtering means, until the desired filtering level is achieved. For filtering in this case, first a modular coarse filtering means is disposed to replace the elimination unit 9, which filtering means removes the largest particles from the fluid. After that, the filtering is performed with a filtering means 7a and finally in a fine filtration module, which together with the coarse filter replaces the elimination unit 9. In the fine filtering module, the filtering after the series of filtering means 7a occurs e.g. with a 1 pm silver-coated filter, in which case bacteria do not grow in the filter itself and the service life of the filter lengthens. Finally the filtering is performed with e.g. a 0.2 or 0.45 pm filter, in which case microbes remain in the filter but the microemulsion fluid itself still passes through the filter.

The filtering means 7a of the filtering unit 7, the fine filtering module and the elimination unit are selected based on the quality and composition of the machining fluid and are adjusted, if necessary, based on the values obtained by measuring the machining fluid. Selectable are thus for microemulsion fluids dense filtering with a fine filtering module and also with filtering means 7a, and for macroemulsion fluids as well as for other machining fluids a combination of filtering occurring by means of filtering means 7a and the elimination unit 9. Owing to the modularity, the configuration of the maintenance apparatus 1 is easy to change according to the machining fluid selected.

The quality (cleaning efficiency and fluid concentration) of the machining fluid is adjusted on the basis of measurement results (measurement of concentration, measurement of contamination) with replacement of the modular filtering means 7a of the filtering unit 7, with automatic adjustment of the concentration of the machining fluid, and with adjustment of the power of the microbe elimination unit 9. Thus, in the method, both the fluid

(concentration) and the apparatus (cleaning efficiency) are adjusted on the basis of measurement results. In the filtering unit 7 is adjustable high pressure, preferably e.g. up to a value of 10 bar. In each of the filtering means 7a of the filtering unit 7 downstream of one another, i.e. in the filtering phase, solid matter of a finer grain than upstream is filtered out of the machining fluid. Preferably the filter material of the filtering means 7a is oleophilic or hydrophobic material, which absorbs oil into itself and rejects water. In this case the filter material allows through the actual machining fluid emulsified in water, but other oil and solid particles remain in the filter. The filter material can be e.g. melt blown polypropylene.

Preferably new machining fluid is added, if necessary, via the intermediate inlet 4 to the flow channel 2a of the machining fluid after the filtering unit 7 and before the measuring unit 8 in the flow direction of the machining fluid to be cleaned. The addition is implemented by means of the dosing valve 4a, which dosing valve 4a can be e.g. a solenoid valve connected to the computer 10. The infeed is arranged to occur automatically under the control of the control & adjustment system of the maintenance device 1 on the basis of the concentration value measured from the machining fluid. In this case the computer-controlled dosing valve 4a allows new machining fluid, adjusted to be suitable in its concentration, into the system through the measuring unit 8. The concentration of the new machining fluid can be adjusted either manually to one level, which is usually sufficient, but when needed the concentration can also be adjusted with the assistance of the computer 10. In conjunction with the addition, the same values are measured from the machining fluid in the measuring unit 8 as otherwise for the machining fluid, but in particular the concentration and the amount of machining fluid. An advantage of the measurement is also that the validity of the calibration of the sensors of the measuring unit 8 can be ensured.

The addition of machining fluid occurring via the intermediate inlet 4 keeps the machining fluid circulating in the system always as far as possible within permitted operating limits. It is also advantageous that the machining fluid reservoir is provided with one or more surface sensors, connected to the control & adjustment system of the maintenance device 1, for measuring the level of the surface of the machining fluid. This solution prevents the machining fluid reservoir flooding over its edges.

In the flow channel 2a, the measuring unit 8 is after the adding point of machining fluid in the flow direction of the machining fluid to be cleaned. The measuring unit 8 comprises one or more measuring means 8a for measuring the properties of the machining fluid to be cleaned and for delivering the measurement results to the control & adjustment system of the maintenance device 1. Such measuring means are, inter alia, a measuring sensor for the amount of dissolved oxygen, an oxidation-reduction potential measuring sensor, a measuring sensor for the pH value of the machining fluid, an electrical conductivity measuring sensor, a measuring sensor for the TDS value of the fluid, as well as a measuring sensor for temperature and flow velocity.

With the measuring sensor for the amount of dissolved oxygen, the amount of free oxygen dissolved in the machining fluid is measured, i.e. the saturation of the machining fluid as regards oxygen. Since microbes consume oxygen, the amount of microbes in the machining fluid can be monitored with this measurement. The more microbes there are in the machining fluid, the lower is the amount of dissolved oxygen. According to the invention, the saturation percentage of dissolved oxygen is measured and calculated, and it is monitored in real-time. The saturation percentage means the amount of dissolved oxygen in relation to the amount of oxygen in a saturated solution. In this case the saturation percentage calculated as a function of time indicates the increased amount of aerobic microbes. The amount of oxygen is preferably measured with a Clark electrode functioning as a sensor in the measuring unit 8, which electrode produces a voltage signal for an A/D converter in the maintenance apparatus 1 or in connection with the apparatus, the digital signal produced by which A/D converter is conducted onwards for processing either in the own computer 10 of the apparatus and/or to an external server. The oxidation-reduction potential describes the oxidation and reduction capability of the solution. The higher the potential is, the greater the tendency of the substance to reduce, i.e. act as an oxidizer. In an oxidation-reduction reaction, the reduction side loses electrons and the oxidation side gains electrons. Although the reaction involves the movement of electrons, i.e. oxygen is not necessarily needed at all, oxygen is often involved. Aerobic microbes are active with a clearly higher potential value whereas anaerobic microbes with a low, or even negative, potential value. In addition to determining the level of microbes, the ability of the fluid to resist changes, more particularly oxidation, is measured by means of the oxidation-reduction potential, which in practice means the breakage of fluid components caused by oxygen. In this way, in the solution according to the invention, the chemical stability of the machining fluid can be advantageously measured with the measuring sensor for the oxidation-reduction potential.

Correspondingly, the pH value of the machining fluid is measured with the measuring sensor of the pH value. Adjusting it affects the functioning of the emulsifier, growth in the amount of bacteria, and also the corrosion of materials in contact with the machining fluid. A pH value that is too low weakens the efficacy of the emulsifier and, correspondingly, a high pH value prevents microbe growth and corrosion. How many ions have dissolved in the machining fluid is determined with the measuring sensor for electrical conductivity. With this data, it can be decided how stable the machining fluid is with regard to forming an emulsion. Correspondingly, with the measuring sensor for the TDS value, it is determined how many solid particles have dissolved in the machining fluid, more particularly salt ions, mineral ions and metal ions (Total Dissolved Solids).

The maintenance apparatus 1 also comprises a measuring means 8b for the concentration of the machining fluid, the means preferably being disposed in the measuring unit 8, or in connection with it, and connected to the flow channel 2a as well as to the control & adjustment system of the maintenance apparatus 1. Together with the dosing valve 4a, the measuring means 8b also functions as an adjusting means of the concentration of the machining fluid, which keeps the concentration of the machining fluid and the fluid surface of the machining fluid reservoir at a regulated level based on the measuring of the measuring means 8b. Preferably the properties of the machining fluid added via the intermediate inlet 4 are measured in the phase when it is added or immediately after it.

Measurement of the concentration is based on its concentration in relation to the refraction of light in the fluid. The measuring means 8b of concentration comprises a device to be used for recording images, preferably a digital camera, in which machine vision is arranged to read light that has travelled through the lens of the camera, from the changes in which light the concentration of dissolved substances in the machining fluid is deduced based on the measured refractive index. The measuring results essential with regard to maintenance of the machining fluid measured from the machining fluid are processed in the computer 10, and adjustment of the essential functions of the maintenance device 1 are arranged to occur automatically. A camera and/or video camera can be used for recording images.

After the measuring unit 8, the flow channel 2a of the machining fluid is connected to the microbe elimination unit 9 via the inlet connector 2b. The elimination unit 9 is preferably a box-shaped space provided with walls and also a cover 9a and with a base 9b or flow platform of essentially large surface area, in which space are one or more radiation sources 16 transmitting radiation destroying microbes, e.g. ultraviolet radiation. Preferably the radiation sources are UV lamps transmitting microbe- destroying UVC radiation, e.g. high-power, low-pressure mercury lamps, but they can just as well be UV LEDs or other types of radiation sources. The radiation sources 16 are situated so that they are not in contact with the machining fluid flowing through the elimination unit 9. The radiation sources 16 can be e.g. in the top part of the elimination unit 9, disposed in such a way that the inlet connector 2b of the machining fluid is between the radiation sources 16 and the top surface of the machining fluid on the base 9b of the elimination unit 9, and that the top surface of the machining fluid is sufficiently far below the radiation sources 16. Between the radiation sources 16 and the top surface of the machining fluid can also be a structure protecting the radiation sources 16 from the machining fluid and from splashes of it. The structure of the elimination unit 9 and its actuators are presented in more detail later in connection with Figs. 4 and 6. After elimination of the microbes in the machining fluid, the machining fluid is funneled from the elimination unit 9, e.g. by means of gravity, via the outlet connector 3a to the machining fluid outlet 3 and onwards into the machining fluid reservoir, where it is recirculated for use by the machine tool or to the maintenance apparatus 1. If necessary, the machining fluid is delivered to the machining fluid reservoir by means of an auxiliary pump, which is presented in Fig. 1 with a dot-and-dash line in the flow channel of the machining fluid before the outlet 3 of the machining fluid.

Fig. 2 presents a simplified side view of one handling apparatus 1 for machining fluid according to the invention and its main components, most of which have been described already in conjunction with the description of Fig. 1. The maintenance apparatus 1 is a fully independent unit, easily movable from one place to another, which can also be provided with wheels to facilitate mobility. The maintenance apparatus 1 also comprises a current connector 12 or current conductor for connecting the apparatus to its operating location in the electricity network, and a current switch 13 for switching the apparatus into operation and for switching off the apparatus.

Fig. 3 presents a simplified view of the top part of the maintenance apparatus 1 according to Fig. 2, as viewed perpendicularly from above with the cover 9a of the device opened. In addition to what is mentioned earlier, the maintenance apparatus 1 comprises a device compartment 14, in which preferably the components and actuators associated with operation of the apparatus are disposed.

Fig. 4 presents a diagrammatic, simplified and sectioned side view of one preferred top part of the maintenance apparatus 1 according to Fig. 2, with the apparatus and at the same time the cover 9a of the elimination unit 9 detached, for the sake of clarity, above the elimination unit 9.

Preferably under the radiation sources 16, between the top surface of the flowing machining fluid and the radiation sources 16, is a protective chute 17 ascending upwards from its free edge as a protective structure for the radiation sources 16. In this embodiment, on the top surface of a protective chute 17 in this case is an essentially upward reflecting surface or reflector 18 and correspondingly on the inner surface of the cover 9a of the elimination unit 9 is an essentially downward reflecting surface or reflector 18a. The reflector 18 is adapted to reflect the UV radiation transmitted to the reflector 18a from the radiation sources 16, which in turn is adapted to reflect

UV radiation directed at itself onto the surface 15 of the machining fluid on the base 9b of the elimination unit 9 or on a separate flow platform, said surface being presented as a dashed line in Fig. 5.

Preferably the essentially upward reflecting reflector 18 is arranged to reflect UVC radiation via the essentially downward reflecting reflector 18a above the radiation sources 16 onto the surface 15 of the machining fluid in the bottom part of the elimination unit 9, e.g. on the base 9b or on a corresponding flow surface, preferably onto the entire surface of the whole surface area of the surface 15 of the machining fluid, or at least almost the entire surface of the whole surface area of the surface 15 of the machining fluid.

The radiation sources 16 and protective chutes 17 are on both side edges of the elimination unit 9 in such a way that a free space of essentially large surface area remains in the center area of the elimination unit 9, above the base 9b, for directing UV radiation at the surface of the machining fluid in the bottom part, e.g. on the base 9b, of the elimination unit 9. Preferably the UV radiation is arranged to be directed at essentially a surface area of the size of the whole base 9b. Preferably the reflectors 18 and 18a are of a material reflecting UVC radiation or they are coated with a material reflecting UVC radiation, e.g. with polytetrafluoroethylene (PTFE), which is also commonly called Teflon.

The desired number of modular elimination units 9 can be connected to the maintenance apparatus 1, one on top of another in the top part of the maintenance apparatus. In this case the elimination efficiency needed can be quickly and easily changed according to the quality of different cleaning fluids and the cleaning need required by them. If, for some reason, there is no need to use the elimination unit 9, or its use weakens the quality of the cleaning fluid, the apparatus 1 can be assembled without the elimination unit 9 and just the filtering unit 7 and fine filtering module can be used for cleaning. Fig. 5 presents a diagrammatic, simplified and sectioned side view of the top part according to one preferred embodiment of the apparatus according to Fig. 2, with the cover 9a of the apparatus detached above the elimination unit 9. In this embodiment, this structure of the elimination unit 9 is otherwise similar to the structure presented in Fig. 4, but now the protective chutes 17 and the essentially upward pointing reflectors 18 are replaced with preferably chute-shaped protection means 19 permeable to UVC radiation, in which case upward pointing reflectors are not needed. For the sake of clarity, the support structures of the protection means 19 are not presented in Fig. 5. The downward-pointing reflector 18a can be similar to the structure presented in Fig. 4. The UVC radiation of the radiation sources 16 now passes both directly through the protection means 19 and as a reflection via the reflector 18a onto the surface 15 of the machining fluid in the bottom part of the elimination unit 9, e.g. on the base 9b or on a corresponding flow surface, preferably onto the entire surface of the whole surface area of the surface 15 of the machining fluid, or at least almost the entire surface of the whole surface area of the surface 15 of the machining fluid. The surface area of the machining fluid to be exposed to UVC radiation can therefore be essentially the whole surface area of the entire base 9b of the elimination unit 9. In the solution according to one preferred embodiment, in the elimination unit 9 between the radiation sources 16 and the surface 15 of the machining fluid is also a thin protective film 19a permeable to UVC radiation. This solution effectively prevents the radiation sources 16 coming into contact with the machining fluid or with splashes of it.

The protection means 19 can be thin films partially permeable to UVC radiation that also partly reflect UVC radiation. In such a case the thickness of the film can be e.g. between 0.02...0.3 mm, suitably between 0.05...0.2 mm and preferably approx. 0.1 mm. Preferably the protection means 19 are PTFE films permeable to UVC radiation.

The protection means 19 can also be thin films that allow UVC radiation to pass through but do not reflect it to any appreciable extent. In such a case the thickness of the film can be e.g. between 0.02...0.2 mm, suitably between 0.04...0.08 mm and preferably approx. 0.05 mm. In this case the protection means 19 can be e.g. fluorinated ethylene propylene films, i.e. FEP films, permeable to UVC radiation, which allow even up to 90% of UVC radiation to pass through. Also the entire surface area exposed to radiation to be covered by a protective film 19a can be this type of FEP film. The whole surface area of the machining fluid in the elimination unit 9 can be covered in this way with this type of protective film, in which case the protection of the radiation sources 16 improves because there is no air contact between the machining fluid and the radiation sources 16. Fig. 6 presents a diagrammatic and simplified view of the data transmission arrangement of a maintenance apparatus 1 for machining fluid according to the invention. The transmitter/receiver 11 of the maintenance apparatus 1 is arranged to transmit, wirelessly 20 and automatically in real-time, the measuring data measured by the measuring means 8a and actuators of the measuring unit 8 of the maintenance apparatus 1 and processed by the computer 10 to an external server 21 for more precise analysis. The analyzed measuring data and other data related to it is arranged to be transmitted from the server 21 onwards wirelessly 22 and automatically, e.g. to a smart device 24 of a user 23 of the machine tool, from which the user 23 is able to examine the operating process 25 of the maintenance apparatus 1 for machining fluid in real-time. Preferably the external server 21 is e.g. a server of the manufacturer of the maintenance apparatus 1. The maintenance apparatus 1 with its control & adjustment system and actuators can also be updated via a transmitter/receiver 11. The maintenance apparatus 1 can also function independently, with or without the assistance of an external server 21. In the method according to the invention the machining fluid to be cleaned is conducted into the inlet 2 of the maintenance apparatus 1, e.g. directly from the machining fluid reservoir. Preferably the machining fluid is conducted from the inlet 2 by means of a suction pump 6a to a high-pressure pump 6b, in which the pressure of the machining fluid is raised to be suitable for passing through the cleaning cycle and filtering unit 7. In the filtering unit 7, the machining fluid is conducted by means of the pressure developed by the high-pressure pump 6b through more than one filtering means 7a connected consecutively in series in such a way that the machining fluid travels first through the coarsest, in terms of its filtering size, filtering means then the second coarsest, and so on, and finally the through the finest filtering means. In each filtering means 7a of the series, finer solid matter than the preceding means in the same series is filtered out of the machining fluid.

After the filtering unit 7, the machining fluid is conducted along the flow channel 2a to the measuring unit 8. Before the measuring unit 8, however, new, ready-mixed machining fluid is added to the machining fluid via an intermediate inlet 4 for increasing the concentration. In the measuring unit 8, the most important properties of the machining fluid from the viewpoint of the condition of the machining fluid are measured by means of the sensors of the measuring means 8a, preferably in real-time, e.g. the amount of free dissolved oxygen, the oxidation-reduction potential and the pH value of the machining fluid, electrical conductivity, total dissolved solids (TDS), and also the temperature and flow velocity. Additionally, the concentration of the machining fluid is measured, preferably in real-time, with a device to be used for recording images, such as with a digital camera and/or digital video camera and a machine vision application in connection with it, which application is arranged to measure the refractive index of the machining fluid and to function in the manner of a digital refractometer.

After the measuring unit 8, the machining fluid is conducted along the flow channel 2a to the microbe elimination unit 9 via the inlet connector 2b. In the elimination unit 9 the machining fluid is spread onto the base 9b of the unit, or onto some other suitable flow platform with a large surface area, in as thin a layer as possible and thus the surface area of the surface of the machining fluid exposed to UV radiation is increased to be as large as possible. The microbes in the machining fluid are destroyed by directing the UVC radiation of the UV radiation sources 16 onto the surface of the machining fluid on the base 9b of the elimination unit, or on some other suitable flow platform. Preferably UVC radiation is directed at the surface area of the whole base 9a, or almost the whole base. The UVC radiation from the radiation sources 16 is directed at the surface of the machining fluid either directly and/or via reflectors 18, 18a. There can be a number of modular elimination units 9 one on top of another in the apparatus 1, or alternatively the apparatus can be manufactured without an elimination unit. Owing to its modularity, adapting the apparatus to changing requirements is easy and fast.

After the elimination unit 9, the machining fluid is conducted via the outlet 3 out of the maintenance apparatus 1 and again back to the machining fluid reservoir or directly to the machine tool. Preferably the machining fluid is circulated in its own dedicated operating cycle essentially continuously from the machining fluid reservoir 1 to the maintenance apparatus 1 and back to the machining fluid reservoir. Another dedicated operating cycle can be from the machining fluid reservoir to the machine tool or machine tools and back to the machining fluid reservoir. From the data transmitted to the server 21, the following, inter alia, are determined: the amount of microbes in the machining fluid, the chemical properties of the fluid, the amount of ions dissolved in the fluid, and also the concentration and temperature. These affect both the service life of the machining fluid and its properties in the machining process, such as its lubrication, thermal transfer and corrosion inhibition, foaming and dimensional accuracy capabilities.

On the basis of the measuring data, and of the data processed based on it, the properties of the machining fluid and also the condition of the maintenance device 1 are monitored and adjusted. In this case, inter alia, the condition of the filtering means 7a is monitored and the measuring means 8a are calibrated if necessary, and also the active status and power of the UVC radiation sources 16 are monitored and adjusted according to need. Monitoring and adjustment are performed essentially in real-time and preferably automatically and/or manually either via a remote connection from a server 21 or manually from a smart device 24 of a user 23. Preferably the data is presented graphically to users of the machining fluids, in which case monitoring and decision-making is effective. The measuring data is also used to predict the remaining service life of the machining fluid.

It is obvious to the person skilled in the art that different embodiments of the invention are not limited to the example described above, but that they may be varied within the scope of the claims presented below. What is essential is that in the solution according to the invention the machining fluid is cleaned as a polyphase continuous process, and that the essential values from the maintenance viewpoint are measured from the machining fluid with the maintenance apparatus according to the invention. Thus, for example, the materials, shapes, dimensions, amounts and size of the main components, as well as their relationships to each other, can also be different to what is presented above.

It is again obvious to the person skilled in the art that also other process fluids than machining fluids can be handled with the method and maintenance apparatus according to the invention, and that the solution according to the invention can be installed in versatile ways for different devices, and that the solution according to the invention is also suited to different sectors, such as e.g. the chemical industry, food industry, and also to general fluid and water cleaning. Furthermore, the solution according to the invention is not limited solely to an industrial environment. It is also obvious to the person skilled in the art that the cleaning efficiency of the maintenance apparatus can be increased by a multifold factor by connecting in series a number of filtering units and/or measuring & cleaning units of the maintenance apparatus by stacking them one on top of another in such a way that the frame part of the maintenance apparatus can be the same for all, and that the serially connected filtering units and/or measuring & microbe elimination units can be adjusted device- specifically.

It is also obvious to the person skilled in the art that also other components can be connected to the cleaning system for machining fluid according to the invention, such as heat pumps to warm and/or cool the fluid as well as larger filtering units, et cetera.