Device for the biocide-free disinfection of cooling lubricants

Abstract

The invention relates to a device (10) for the biocide-free disinfection of cooling lubricants, comprising a withdrawal line (24, 28), a pump (32) for conveying the cooling lubricant through the device (10), a heating assembly (38) for heating the cooling lubricant to be disinfected to a disinfection temperature, and a discharge line (26, 42) for discharging the disinfected cooling lubricant from the device (10). The invention is characterized in that a reactor (36) is provided downstream of the heating assembly (38) in the conveying direction, said reactor being designed to maintain the heated cooling lubricant at the disinfection temperature in the reactor (36) for a predetermined period of time before the cooling lubricant leaves the reactor (36).

Description

[0001] Device for biocide-free disinfection of cooling lubricants

[0002] The invention relates to a device for the biocide-free disinfection of cooling lubricants according to the type specified in the preamble of claim 1.

[0003] Cooling lubricants are used in manufacturing technology during workpiece machining, for example during cutting and forming, on machine tools to dissipate heat and reduce friction between the tool and workpiece through lubrication. Additionally, in some machining processes, cooling lubricants also serve to remove chips by rinsing them from the working environment, thereby ensuring better dimensional accuracy of the workpiece and improved surface finish.

[0004] Mixed friction is the primary factor in machining and forming processes. Cooling lubricants reduce friction through lubrication, thereby minimizing tool wear, workpiece heating, and energy consumption. Additives can be incorporated into cooling lubricants to tailor them to a wide range of requirements.

[0005] Cooling lubricants are designed to remove heat from the point of contact as quickly as possible to prevent changes in the microstructure of the surface layers of the tool and workpiece. Machining accuracy also benefits from good cooling. In water-miscible cooling lubricants, the high heat capacity of the water content contributes to cooling in addition to the evaporation of the water.

[0006] A distinction is made between two types of cooling lubricants: non-water-miscible and water-miscible. -2 WO BO / mg 05.09.2025 Water-miscible cooling lubricants, in particular, are regularly contaminated by microorganisms (fungi and bacteria) in use. During extended work breaks, for example, on weekends, bacteria can multiply. This can be noticeable through strong odors and possibly also discoloration of the cooling lubricant. Infestation often results in health problems for workers who come into contact with cooling lubricants. In addition to frequently occurring minor inflammations of everyday wounds, skin rashes and allergic reactions can also occur. Technical problems can be caused by the blockage of pipelines by fungal filaments and / or slime bacteria.Bacterial growth can also change the pH value of cooling lubricants and consequently attack the metallic materials of the workpieces being machined and the tools used.

[0007] There are few methods for combating bacteria and fungi in cooling lubricants. Irradiation with ultraviolet light is widely used. This works relatively easily with transparent liquids. However, with cooling lubricants, UV rays only penetrate superficially due to their milky appearance and impurities. Therefore, the cooling lubricant must be reduced to such a thin film that UV light can penetrate it. This proves to be a major challenge in practice, and the results are often modest: often only about 60-80%, and sometimes even less than 50%, of the bacteria and fungi present in the cooling lubricant are killed.

[0008] The most widespread use is that of biocides, i.e., bactericides and fungicides. These undoubtedly have the advantage of being cost-effective and very efficient. However, biocides are classified as hazardous substances under the EU's CLP Regulation (Regulation on Classification, Labelling and Packaging of Substances and Mixtures), requiring proper and therefore expensive handling.

[0009] Biocides can cause considerable health problems. These range from minor inflammation of everyday wounds and skin rashes to allergies and irritation of the skin, eyes, and mucous membranes. Concentrates, in particular, which are being used more and more frequently, must never come into contact with the skin, as even the smallest splashes can lead to significant health damage. -2 WO BO / mg 05.09.2025 Avoiding biocides would therefore reduce the health risks for employees and tend to help reduce sick leave.

[0010] It is known that biocides can be avoided by thermally disinfecting cooling lubricants to remove bacteria and fungi. For this purpose, ph-cleantec offers a mobile device that draws cooling lubricant from the coolant reservoir of a machine tool and heats it to over 65°C. The mobile device is equipped with a suction hose and a pump that draws the cooling lubricant to be disinfected from the reservoir and continuously passes it through a heating unit. The heating unit heats the cooling lubricant to over 65°C, and it is then returned to the cooling lubricant reservoir via a discharge hose. This process continues until, for example, the cooling lubricant reservoir contains only a predetermined number of colony-forming units per milliliter (CFU / ml) of bacteria. The upper limit is 10 6CFU / ml. If the limit is exceeded, disinfection is mandatory.

[0011] In terms of results, thermal disinfection is certainly one of the most efficient methods for disinfecting cooling lubricants. Since it requires no chemicals or biocides, it is also environmentally friendly and safe for human health. Finally, thermal disinfection is extremely cost-effective, requiring only a small investment in a disinfection machine and low operating costs, primarily electricity. Furthermore, disinfection can be carried out during ongoing production. This also disinfects the cooling lubricants in the machine tool's lines. Consequently, there are no machine tool downtime costs during the disinfection process.

[0012] However, the well-known thermal disinfection method has the disadvantage that it does not guarantee complete disinfection of all cooling lubricants. Furthermore, operating costs have increased considerably due to rising energy costs, specifically electricity costs.

[0013] The invention is therefore based on the objective of providing a device for the biocide-free disinfection of cooling lubricants, which reduces the germ load more efficiently and also operates more economically.

[0014] This problem is solved, according to a first aspect of the invention, by the characterizing features of claim 1 in conjunction with its preamble features. -2 WO BO / mg 05.09.2025 The dependent claims constitute advantageous embodiments of the invention.

[0015] The invention is based on the understanding that the efficiency of reducing microbial contamination depends not only on the temperature alone, but also on the duration for which the cooling lubricant is held at a predetermined sterilization temperature to ensure complete sterilization. Furthermore, heat energy from the sterilized cooling lubricant can be transferred to the cooling lubricant being sterilized, thereby reducing energy costs.

[0016] The device for biocide-free disinfection of cooling lubricants according to the invention is equipped with a dispensing line, a pump for conveying the cooling lubricant through the device, a heating unit for heating the cooling lubricant to be disinfected to a disinfection temperature, and a discharge line for dispensing the disinfected cooling lubricant from the device. According to the invention, a reactor is provided downstream of the heating unit, which maintains the heated cooling lubricant at the disinfection temperature in the reactor for a predetermined period before the cooling lubricant leaves the reactor. By keeping the cooling lubricant at the disinfection temperature for a predetermined period, it can be easily ensured that all germs are killed.

[0017] Preferably, the reactor is designed such that the cooling lubricant remains in the reactor for at least 15 seconds, preferably 20 seconds, and particularly 30 seconds. It has been shown that complete elimination of germs is possible within this timeframe for all cooling lubricants at predetermined sterilization temperatures.

[0018] To maintain the cooling lubricant at a predetermined sterilization temperature within the reactor, the reactor is equipped with a temperature sensor that interacts with a control device, which in turn interacts with the heating unit. This allows the heating unit to be adjusted accordingly, ensuring that the predetermined sterilization temperature is maintained in the cooling lubricant until just before it exits the reactor.

[0019] In particular, the control device, in conjunction with the temperature sensor and the heating unit, limits temperature deviations of the sterilization temperature in the reactor to up to -2 WO BO / mg 05.09.2025 ■+ / -0.5°C (switching temperature difference). This ensures high quality and reliability of the sterilization of the cooling lubricant.

[0020] Proteins, and therefore bacteria and fungi, are destroyed at temperatures above 60°C. To operate as efficiently as possible in a continuous process, higher temperatures are targeted in the prior art. However, this is disadvantageous with regard to optimizing energy consumption. According to the invention, in conjunction with the reactor and the associated period during which the cooling lubricant remains at the sterilization temperature in the reactor, the heating unit can now heat the temperature of the cooling lubricant to above 60°C, but does not need to exceed a maximum of 64.5°C. In particular, the sterilization temperature should be in a temperature range between 60°C and 64°C, especially preferably in a temperature range between 60°C and 63°C, and more preferably between 60°C and 62.5°C.

[0021] According to an advantageous embodiment of the invention, the residence time in the reactor is controlled as a function of the predetermined sterilization temperature, for example, by adjusting the pump's delivery rate or by a throttle, preferably adjustable, for the cooling lubricant located downstream of the pump, and preferably the reactor. The following relationship results: The lower the sterilization temperature, the longer the cooling lubricant must remain at the sterilization temperature in the reactor. The higher the sterilization temperature, the shorter the residence time of the cooling lubricant in the reactor.

[0022] To reduce energy consumption, at least one heat exchanger is provided, which is located upstream of the heating unit, through which the cooling lubricant to be disinfected can be heated by the heat emitted by the disinfected cooling lubricant and the disinfected cooling lubricant can be cooled.

[0023] Preferably, several heat exchangers are provided for this purpose in order to transfer as much heat as possible from the sterilized coolant to the coolant being sterilized. The heat exchangers are, in particular, connected in series for this purpose.

[0024] The heat exchanger(s) can have a capacity sufficient to cool the sterilized cooling lubricant to at least 25°C, in particular to at least 24°C, preferably to 23°C. 23°C generally corresponds to room temperature. -2 WO BO / mg 05.09.2025 According to a further advantageous embodiment, the heat exchanger is designed as a plate heat exchanger.

[0025] In particular, the surface of the plate heat exchanger is textured to increase the surface area for efficient heat transfer.

[0026] Plate heat exchangers are generally available with H, L, and M surface textures. The M texture is preferred because it creates a large "thermal length," allowing for the transfer of heat even with minimal temperature differences. This texture offers very good specific heat output with low pressure drop.

[0027] Preferably, the pump has a delivery rate of at least 7.5 liters per minute, and in particular 10 liters per minute. This delivery rate ensures optimal disinfection results.

[0028] To increase the effectiveness of the disinfection process, a UV lamp is integrated into the reactor so that the cooling lubricant to be disinfected is additionally disinfected using UV light. For this purpose, the cooling lubricant to be disinfected is passed by the UV lamp in the reactor.

[0029] The above-mentioned problem is also solved according to a further aspect of the invention by a method for biocide-free disinfection of cooling lubricants with a device as just described, in which the residence time of the cooling lubricant in the reactor is at least 15 seconds, preferably 20 seconds, in particular 30 seconds at disinfection temperature.

[0030] The inlet temperature to the reactor can be above 60°C but not more than 64.5°C, in particular in a temperature range between 60°C and 64°C, especially preferably in a temperature range between 60°C and 63°C, preferably between 60°C and 62.5°C.

[0031] Preferably, the temperature deviations of the sterilization temperature of the cooling lubricant in the reactor are limited to a range of up to + / -0.5°C of the sterilization temperature (switching temperature difference).

[0032] Furthermore, the cooling lubricant can be cooled to at least 25°C, in particular at least 24°C, preferably to 23°C, i.e., to room temperature, after the reactor. -2 WO BO / mg 05.09.2025 It has proven to be particularly energy-efficient to feed the heat extracted from the cooling lubricant back into the cooling lubricant before it enters the heating unit.

[0033] The cooling lubricant can be conveyed through the device at a flow rate of at least 7.5 liters per minute, in particular 10 liters per minute.

[0034] Further advantages, features and application possibilities of the present invention will become apparent from the following description in conjunction with the exemplary embodiments shown in the drawings.

[0035] The description, claims, and drawing use the terms and associated reference numerals listed below. In the drawing, this means:

[0036] Fig. 1 schematic side view of a device according to the invention, and

[0037] Fig. 2 shows a schematic representation of the individual steps in the disinfection process using the device according to Fig. 1.

[0038] Figure 1 shows a schematic side view of a device 10 for biocide-free disinfection, comprising a housing 12. The housing 12 is cuboid in shape. On the front side 12a, underneath the housing 12, it is provided with rotatable rollers 14. On the rear side 12b, underneath the housing 12, it has two fixed rollers 16 aligned longitudinally. The rollers 14 and 16 are located in the corner regions of the housing 12 and connected to a base 12c of the housing 12.

[0039] The rollers 14 are equipped with a parking brake 18, which can be activated and deactivated by pivoting about an axis parallel to the axis of the associated roller 14 using a foot.

[0040] The upper part of the housing 12 is provided with a cover 12d. In the area of ​​the cover

[0041] In the rear area 12b, a handrail 20 extending transversely to the housing is provided, which is connected to the housing 12 laterally via a bracket 22. -2 WO BO / mg 05.09.2025 The housing 12 is provided with a side wall 12e on each side. On the side wall 12e, which is located on the left side when looking towards the front side 12a, an inlet opening 24 for introducing cooling lubricant to be sterilized is provided in the area of ​​the bottom 12c, as well as an outlet opening 26 to the side of it for dispensing sterilized cooling lubricant from the device 10.

[0042] A first line 28 connects to the inlet opening 24 and runs to a plate heat exchanger 30, where it opens into a first inlet opening 30a. A pump 32 is connected to the first line 28.

[0043] At the end of the plate heat exchanger 30 furthest from the first line 28, there is a first outlet opening 30b, to which a second line 34 is connected, extending to a reactor 36. A heating unit 38 is interposed in the second line 34 between the plate heat exchanger 30 and the reactor 36.

[0044] At an inlet opening 36a of the second line 34, located on the side furthest from the reactor 36, there is an outlet opening 36b of the reactor 36, to which a third line 40 is connected. The third line 40 opens into a second inlet opening 30c of the plate heat exchanger 30. At the far end of the second inlet opening 30c, an outlet opening 30d is provided in the plate heat exchanger 30, to which a fourth line 42 is connected, terminating in the outlet opening 26 of the casing 12.

[0045] The cooling lubricant to be disinfected, introduced via the inlet opening 24, is conveyed by the feed pump 32 from the inlet opening 24 via the first line 28 to the plate heat exchanger 30 and then via the second line to the heating unit 38 and the reactor 36. A UV lamp is integrated into the reactor 36 such that the liquid to be disinfected passes through the UV light of the lamp. The cooling lubricant is disinfected in the reactor 36. The disinfected cooling lubricant is then fed via the third line 40 to the plate heat exchanger 30 and finally via the fourth line 42 to the outlet opening 26 of the housing. The disinfected cooling lubricant is conveyed out of the device 10 via the outlet opening.

[0046] During the sterilization process, the inlet opening 24 is connected via a hose to a tank containing the coolant to be sterilized. The outlet opening 26 is also connected to the tank via another hose. The sterilized coolant is returned to the tank (Tank-2 WO BO / mg 05.09.2025) via the second hose. Through this continuous supply and sterilization process, all the coolant in the machine tool connected to the tank is ultimately sterilized over a specific period of time.

[0047] The device 10 is mobile thanks to the rollers 14, 16 and is moved as needed to the tanks of the machine tools for disinfecting the cooling lubricant.

[0048] The heat from the sterilized coolant is transferred to the coolant being sterilized in the plate heat exchanger 30. For this purpose, the sterilized coolant and the coolant being sterilized flow in opposite directions in separate channels within the plate heat exchanger 30. To optimize heat transfer, the contact surfaces of the channels, and thus the contact surfaces of the coolant with the plate heat exchanger 30, are embossed with a so-called M-shaped pattern.

[0049] The reactor 36 is equipped with a temperature sensor 44, which measures the temperature of the cooling lubricant to be disinfected within the reactor 36 and transmits this value to the control unit 46 via a line 48. Depending on the delivery rate of the feed pump 32 and the specified disinfection temperature, the heating unit 38 is activated or deactivated, or the heating power is increased or decreased accordingly. The control device limits temperature deviations of the disinfection temperature in the reactor 36 to up to +1 to 0.5 °C (switching temperature differential).

[0050] Figure 2 shows the individual steps to carry out a disinfection operation.

[0051] In a first step S1, the device 10 is moved to a coolant tank. Hoses are connected to the inlet opening 24 and the outlet opening 26. The other ends of the hoses are placed in the coolant tank.

[0052] In the next step S2, the feed pump 32 is started, which pumps the coolant to be disinfected from the coolant tank of the machine tool via the hose, the inlet opening 24, and the first line 28, through the plate heat exchanger 30, the second line 34, and the heating unit 38 to the reactor 36. The feed pump operates at a flow rate of 10 l / min. The plate heat exchanger 30 and the subsequent heating unit 38 heat the coolant to be disinfected to a disinfection temperature between 60°C and 62.5°C.

[0053] In the next step S3, the cooling lubricant to be disinfected, heated to the disinfection temperature, flows through reactor 36 with the integrated UV lamp 50 for a predetermined period. The cooling lubricant to be disinfected remains at the disinfection temperature in reactor 36 for a period of 30 seconds.

[0054] In a fourth step S4, the now sterilized, but still heated, cooling lubricant is fed via line 40 to the plate heat exchanger 30. In the plate heat exchanger 30, the heat is transferred to the cooling lubricant still requiring sterilization. Several plate heat exchangers 30 can be arranged in series. The sterilized cooling lubricant is thereby cooled to 23 °C, i.e., room temperature.

[0055] In the last step S5, the cooled, sterilized coolant is pumped from the plate heat exchanger via the fourth line 42, the outlet opening 26, and the subsequent hose back into the coolant tank.

[0056] The operation of the device 10 is maintained until the coolant from the coolant tank and the cooling circuit for a machine tool supplied from the coolant tank, including the lines, have been disinfected.

[0057] According to an embodiment not shown here, an adjustable throttle can be connected downstream of the reactor 36 to easily set the predetermined residence time in the reactor 36. Without a throttle, the predetermined residence time is ensured by guiding the flow of the cooling lubricant in conjunction with the feed pump 32.

[0058] The invention is characterized by the fact that, firstly, considerable energy savings can be achieved because the sterilization temperature is kept lower compared to the prior art, and secondly, the sterilization effectiveness is significantly increased through the use of the reactor and the associated residence time of the cooling lubricant to be sterilized at the sterilization temperature. -2 WO BO / mg 05.09.2025 Reference numeral list

[0059] 10 Device

[0060] 12 cases

[0061] 12a front of the housing 12

[0062] 12b rear of the case 12

[0063] 12c Bottom of the case 12

[0064] 12d Cover of the housing 12

[0065] 12e Side walls of the housing 12

[0066] 14 swivel casters

[0067] 16 fixed casters

[0068] 18 Parking brake for the swivel caster 14

[0069] 20 Handrail

[0070] 22 holders

[0071] 24 Inlet opening of the housing 12

[0072] 26 Outlet opening of the housing 12

[0073] 28 first line

[0074] 30 plate heat exchangers

[0075] 30a first entrance

[0076] 30b first exit opening

[0077] 30c second entrance

[0078] 30d second exit opening

[0079] 32 Pump

[0080] BO / mg 05.09.2025 34 second line

[0081] 36 Reactor

[0082] 36a Reactor entrance 36

[0083] 36b Outlet opening of reactor 36

[0084] 38 Heating unit

[0085] 40 third line

[0086] 42 fourth line

[0087] 44 Temperature sensor

[0088] 46 Control unit

[0089] 48 Management

[0090] 50 UV lamps

[0091] 51 first step

[0092] 52 second step

[0093] 53 third step

[0094] 54 fourth step

[0095] 55 fifth step

[0096] BO / mg 05.09.2025

Claims

Patent claims 1. Device (10) for biocide-free disinfection of cooling lubricants comprising a withdrawal line (24, 28), a pump (32) for conveying the cooling lubricant through the device (10), a heating unit (38) for heating the cooling lubricant to be disinfected to a disinfection temperature and a discharge line (26, 42) for dispensing the disinfected cooling lubricant from the device (10), characterized in that a reactor (36) is provided in the conveying direction downstream of the heating unit (38), which is designed to maintain the heated cooling lubricant at the disinfection temperature in the reactor (36) for a predetermined period of time before the cooling lubricant leaves the reactor (36).

2. Device according to claim 1, characterized in that the reactor (36) is designed such that the cooling lubricant remains in the reactor for at least 15 seconds, preferably 20 seconds, in particular 30 seconds.

3. Device according to claim 1 or 2, characterized in that the reactor (36) has a temperature sensor (44) which interacts with a control device (46) which in turn interacts with the heating unit (38).

4. Device according to claim 3, characterized in that the control device (46) limits temperature deviations of the sterilization temperature in the reactor (36) to up to + / -0.5°C (switching temperature difference).

5. Device according to one of the preceding claims, characterized in that the heating unit (38) heats the temperature of the cooling lubricant to above 60°C but not more than 64.5°C, in particular in a temperature range between 60°C and 64°C, O BO / mg 05.09.2025 particularly preferably in a temperature range between 60°C and 63°C, preferably between 60°C and 62.5°C.

6. Device according to one of the preceding claims, characterized in that the residence time in the reactor (36) is controlled as a function of the predetermined sterilization temperature, for example by adjusting the delivery rate of the pump (32), or a throttle for the cooling lubricant connected downstream of the pump (32), preferably the reactor (36), in particular adjustable.

7. Device according to one of the preceding claims, characterized in that at least one heat exchanger (30) is provided, which is connected upstream of the heating unit (38), via which the cooling lubricant to be disinfected can be heated by the heat emitted by the disinfected cooling lubricant and the disinfected cooling lubricant can be cooled.

8. Device according to one of the preceding claims, characterized in that several heat exchangers (30) are provided, which are in particular connected in series.

9. Device according to one of claims 7 or 8, characterized in that the heat exchanger (30) or heat exchangers (30) have a capacity such that the sterilized cooling lubricant can be cooled to at least 25°C, in particular at least 24°C, preferably 23°C.

10. Device according to one of claims 7 to 9, characterized in that the heat exchanger is designed as a plate heat exchanger (30).

11. Device according to claim 10, characterized in that the surface of the plate heat exchanger (30) is embossed.

12. Device according to claim 11, characterized in that the surface of the plate heat exchanger (30) is provided with an M-embossing.

13. Device according to one of the preceding claims, characterized in that the pump (32) has a delivery rate of at least 7.5 liters per minute, in particular 10 liters O BO / mg 05.09.2025 per minute.

14. Method for biocide-free disinfection of cooling lubricants with a device (10) according to one of the preceding claims, characterized by a residence time in the reactor (36) of at least 15 seconds, preferably 20 seconds, in particular 30 seconds.

15. Method according to claim 14, characterized in that the inlet temperature to the reactor (36) is above 60°C but not more than 64.5°C, in particular in a temperature range between 60°C and 64°C, particularly preferably in a temperature range between 60°C and 63°C, preferably between 60°C and 62.5°C.

16. Method according to claim 15, characterized in that the temperature deviations of the sterilization temperature of the cooling lubricant in the reactor (36) are limited to a range of up to + / -0.5°C of the sterilization temperature (switching temperature difference).

17. Method according to claims 14 to 16, characterized in that the cooling lubricant is cooled to at least 25°C, in particular at least 24°C, preferably 23°C, after the reactor (36).

18. Method according to claim 17, characterized in that the amount of heat extracted from the cooling lubricant is supplied to the cooling lubricant upstream of the heating unit (38).

19. Method according to any one of claims 14 to 18, characterized in that the cooling lubricant is conveyed through the device (10) at a delivery rate of at least 7.5 liters per minute, in particular 10 liters per minute. O BO / mg 05.09.2025

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