Method for removing oil from metal chips, and equipment for removing oil from metal chips.

Abstract

An oil removal apparatus for removing oil from non-ferrous metal chips comprises a container for metal chips and a container for recovered oil. The container for metal chips works in cooperation with a magnetic field generating member, and when either the container for metal chips or the magnetic field generating member rotates, it generates a rotating magnetic field that affects the metal chips and passes through them, heating the metal chips. The oil evaporates from the metal chips and is then condensed and recovered in the oil container. A method for removing oil from metal chips is also described and claimed.

Description

Technical Field

[0001] The present invention relates to a method and equipment for removing oil from metal chips, as described in the preamble of the corresponding independent claim.

[0002] As is known, metal working processes such as turning, cutting, milling and drilling produce metal product chips. In addition to transporting workpieces in the processing area, these processing operations also use aqueous or oily cutting fluids, which include light oil, heavy oil, aqueous emulsions and the like. In the present specification, such cutting fluids are simply referred to by the term "oil". Oil is not only used as a lubricant, but also serves to reduce heat and friction generated by tools in the processing area. As a result, the generated chips retain a considerable amount of oil, which hinders their direct reuse in factories, for example.

[0003] Therefore, it is necessary to remove residual oil present on the chip surface so that the metal material can be reused, that is, recycled. In this regard, various methods and equipment for removing oil from chips, although partial, are currently known.

[0004] The first of these removal methods uses water containing detergents and / or solvents to clean chips heated to a temperature of about 80°C. This method requires a large amount of water, and therefore requires periodic treatment of the water. Equipment for performing water-based cleaning is remarkably large and comprises at least one large cylindrical container rotationally driven about a longitudinal axis. Alternatively, one or more augers are provided within the cylindrical container to move the chips.

[0005] The aforementioned prior art methods have been shown to have several problems. The first and most significant problem is that, although only a small portion of the oil is recovered (yet requiring highly specialized equipment), at least several percent of oil and water remain on the chips. Furthermore, there are problems with oil-water separation, along with issues related to the treatment of the wash water. As previously mentioned, the treated water contains a large amount of oil (the oil concentration may vary). The emulsion, solvent, and / or detergent mixture of water and oil is extremely contaminant and cannot be treated under normal conditions. Therefore, treatment must be carried out with extreme care and at considerable expense.

[0006] In addition to that, a related problem is the high consumption of heated water.

[0007] Furthermore, companies that provide cleaning facilities typically do not offer any water or wastewater treatment services, and the same applies to waste oil treatment facilities. Consequently, these waste materials must be stored, requiring a large amount of space for storage.

[0008] Furthermore, the cleaned tips need to be dried to remove any remaining moisture.

[0009] Another prior art method for removing residual oil from metal chips utilizes ultrasound. The metal chip is immersed in a tank containing a liquid, primarily water with additives. A dedicated piezoelectric transducer (or a similar high-frequency resonant generator) emits ultrasound waves, which shock the metal chip and partially remove the oil from it.

[0010] This prior art method also requires drying the cleaned metal chips using a dryer. Therefore, the same problems as previously pointed out regarding the method of cleaning metal chips arise with respect to the treatment of water containing oil, additives, and detergents.

[0011] Another prior art method for removing oil from metal chips utilizes centrifugal force. This method, using a centrifuge capable of continuous cycle operation, can, in the best case, reduce the centrifuged material to a moisture residue (oil) of approximately 2%. However, even with this method, the amount of residual oil in the metal chips is still at a level that causes problems when the metal chips are introduced into a melting furnace. In fact, the presence of oil causes chemical changes in the metal material, generating gases in the melting furnace. These gases must be properly filtered before being released into the atmosphere.

[0012] Furthermore, because centrifugal separators are quite large, centrifugal separator plants occupy a vast area.

[0013] Another method used to remove oil from metal chips generated during machining involves pyrolysis carried out in a state-of-the-art pyrolysis reactor equipped with an auger made of ceramic or stainless steel. The associated problems with this method are that the plant becomes larger, requiring not only a considerably large pyrolysis reactor itself, but also a considerably large facility for loading and unloading the metal chips into the reactor.

[0014] Within the pyrolysis reactor, a gas usable by the burner and a liquid, partly formed from hydrocarbons and also usable by the burner, are generated. Furthermore, the burner must be equipped with a flue gas treatment and reduction system to treat the flue gas before releasing it into the atmosphere.

[0015] However, these systems are extremely expensive, require a lot of energy to operate, and while they can process small amounts of metal chips, they produce residues that are costly to process and difficult to deal with.

[0016] Other methods involve using infrared radiation to evaporate the oil from the metal chips, or utilizing the high-temperature gas discharged from the melting furnace. In this case, the metal chips are placed in a chamber (with a chimney) above the melting furnace and then exposed to the high-temperature gas. After the oil has evaporated at least partially (or after a predetermined residence time has elapsed), the metal chips are mechanically fed into the melting furnace and allowed to fall in by gravity. With this method, there is no guarantee that the temperature of the metal chips can be precisely controlled. Therefore, the temperature of the metal chips can cause changes in their chemical composition to the extent that it impairs their metallurgical properties.

[0017] In all of the prior art cases, the gases (oil-rich smoke and vapor) generated during processing are not taken into consideration. Such oil-rich smoke and vapor must not be directly discharged into the atmosphere without special treatment or filtration.

[0018] European Patent Publication 2862948A1 discloses a method for removing petroleum substances from materials contaminated with petroleum substances. In this method, the contaminated material is purified by indirect heating in a sealed furnace to a temperature between 250°C and 750°C, and the sealed space of the furnace is cleaned with a protective gas atmosphere having a maximum oxygen content of 15% by volume. Subsequently, the mixture of gas and water vapor produced by evaporation and further decomposition of liquids derived from the petroleum substances and contaminated materials present in the furnace is discharged from the sealed space of the furnace and cooled to condense.

[0019] During the refining process, materials contaminated with petroleum substances are mixed, heated to the target temperature, and after the refining process is complete, the contaminated materials are cooled by the water atomization method.

[0020] During condensation, the non-condensable portion of the gas-water vapor mixture is discharged for further processing and / or at least partially returned to the purification process as a process gas.

[0021] This prior art document also discloses a refining furnace having a heat source that indirectly heats the sealed space of the furnace, and an outlet for extracting material from which petroleum substances have been removed, as well as an inlet for introducing material contaminated with petroleum substances. The furnace is equipped with a supply inlet for supplying inert gas from a pressurizing source, as well as a mixing device provided within the furnace space for mixing the materials to be fed in.

[0022] A pipe is provided for extracting a mixture of gas and steam, which is produced by the decomposition and evaporation of the input fluid and sent to a condenser equipped with branched outlet pipes for each condensation product.

[0023] British Patent No. 635436A discloses a vacuum distillation method in which an evaporation surface made of a conductive material is rotated, a component to be distilled is placed on the evaporation surface in a magnetic field generated by several suitable magnets, and the temperature is raised to the distillation point using eddy currents generated within the evaporation surface. The magnets may be U-shaped and the heating effect may be controlled by adjusting their proximity to the rotating surface, or the magnets may be electromagnets and the degree of heating may be controlled by changing the current flowing through the electromagnets.

[0024] By heating the evaporation surface, the component to be distilled is evaporated, recovered by condensation on the surface covering the evaporation surface, dropped into a ring-shaped recovery channel, and extracted through a dedicated extraction channel. [Overview of the project] [Problems that the invention aims to solve]

[0025] The object of the present invention is to provide a method and apparatus for removing oil from metal chips made of non-ferrous metal materials derived from machining processes ("oil removal"), which is an improvement over prior art processing methods and equipment for removing oil from metal chips.

[0026] In particular, an object of the present invention is to provide a method for removing oil from a metal chip, which removes at least almost all of the oil present inside and on the surface of the metal chip, thereby reducing the amount of oil residue to 0.4% or less of the amount of oil before treatment.

[0027] Another object of the present invention is to provide a method of the above-mentioned type, which is environmentally friendly when implemented, does not generate materials to be discarded or special waste, and results in a closed system (circular economy). In particular, the method according to the present invention aims to provide part of a circular economic system for manufacturing mechanical parts by machining using cutting oil and recovering chips generated thereby.

[0028] Another object of the present invention is to provide a method for removing oil from metal chips, which enables the metal chips to be reused in a melting furnace after the treatment is completed, without requiring pretreatment such as drying and without causing metallurgical changes such as oxidation to the metal chips.

[0029] Another object of the present invention is to provide an apparatus for implementing the above type, which is compact and reduced in overall size, but has high performance, and can recover oil adhering to the surfaces and inside of metal chips with a cleanliness that allows the recovered oil to be reused in machining processes.

[0030] Another object of the present invention is to provide an apparatus for implementing the above type, which is more cost-effective than known similar apparatuses.

[0031] Another object of the present invention is to provide an apparatus for implementing the above type, which has high energy efficiency and can be fully automatically operated throughout the entire process. Means for Solving the Problem

[0032] These objects, and other objects that will be further apparent to those skilled in the art, are achieved by the method and apparatus described in the independent claims. Brief Description of the Drawings

[0033] To facilitate a better understanding of the present invention, the following drawings, which are merely given by way of non-limiting example, are attached. [Figure 1] It is a schematic diagram showing a first embodiment of the apparatus according to the present invention. [Figure 2] Figure 1 is a perspective view showing a portion of the equipment. [Figure 3] Figure 2 is a top view of the portion shown. [Figure 4] This is a cross-sectional view along line 4-4 in Figure 3. [Figure 5] This is a cross-sectional view along line 5-5 in Figure 4. [Figure 6] This is a cross-sectional view along line 6-6 in Figure 5. [Figure 7] This is a cross-sectional view along line 7-7 in Figure 3. [Figure 8] This is an enlarged view showing details of the area marked with symbol A in Figure 7. [Figure 9] This shows a further portion of the equipment shown in Figure 2. [Figure 10] Figure 9 shows an enlarged view of a further portion of the component. [Figure 11] This is a cross-sectional view along line 11-11 in Figure 10. [Figure 12] This is an upper perspective view showing a second embodiment of a part of the equipment according to the present invention. [Figure 13] This is a cross-sectional view along line 13-13 in Figure 12. [Figure 14] This is a cross-sectional view along line 14-14 in Figure 13. [Figure 15] This is a cross-sectional view along line 15-15 in Figure 14. [Figure 16] This is an enlarged view showing some of the components of the equipment shown in Figure 12. [Figure 17] This is a perspective view showing another component of the equipment shown in Figure 12 during one step of implementing the method according to the present invention. [Figure 18] This is a perspective view showing another component of the equipment shown in Figure 12 in another stage of implementing the method according to the present invention. [Figure 19] This is a schematic side view showing a third embodiment of the equipment according to the present invention. [Figure 20] Figure 19 is a perspective view of a part of the equipment shown. [Modes for carrying out the invention]

[0034] Referring to the attached drawings above, a first embodiment of an oil removal device for removing residual oil from metal chips is shown in Figures 1 to 11. The oil removal device according to the first embodiment comprises a cylindrical container 1 configured to accommodate metal chips derived from metal processing of metal products. The cylindrical container 1 is a cylindrical body 12 (see, for example, Figure 4), which is hollow at the location indicated by reference numeral 13, closed at the bottom by a movable and openable / closable lower closing member 14, and closed at the top by a removable, i.e., openable / closable lid 15. A beam 16 (see Figure 2) which is combined with a lifting member (not shown) is attached to the lid 15, and the cylindrical body 12 can be opened and closed by the operation of the lifting member. The cylindrical body is configured to accommodate metal chips from which oil should be removed in its hollow portion 13. The metal chips are placed in the hollow portion through the end of the cylindrical body 12 to which the lid 15 is attached.

[0035] The lower closing member 14 preferably includes a connecting member 17 to a pipe 18 connected to an inert gas, preferably nitrogen gas, storage unit 19. Between the inert gas storage unit 19 and the cylindrical body 12, a conventional solenoid valve 9 equipped with a check valve and a conventional pressure reducer 20 are provided.

[0036] In a preferred embodiment of the invention described above, the connecting member 17 opens into the inert gas diffusion chamber 21 (see Figure 8). The diffusion chamber for the inert gas (hereinafter sometimes abbreviated as nitrogen) is composed of a lower closing member 14 and a bottom plate 22 (see in particular the one shown in Figure 5). The bottom plate has a shape like a recessed plate and is placed on the lower closing member 14 and fixed to the lower closing member. Between the bottom plate 22 and the lower closing member 14, a plurality of flow paths 24 for nitrogen diffusion are provided within the inert gas diffusion chamber 21, and the ends of the flow paths are located near the edge 25 of the bottom plate. Between the edge 25 of the bottom plate and the lower closing member 14, a space is provided that allows nitrogen to enter the hollow portion 13 of the cylindrical body 12.

[0037] This configuration allows the inert gas to be evenly distributed throughout the metal chip within the hollow section 13. It is clear that the present invention may also involve not allowing the inert gas to enter the inert gas diffusion chamber 21. The use of inert gas is not essential. Using inert gas reduces the risk of oxidation of the metal chip, which helps improve yield and subsequent melting processes in the foundry.

[0038] Referring specifically to Figure 6, the hollow section 13 (the section housing the metal chip) is divided into several sections (at least two sections) 13A, 13B, and 13C by a plurality of partition walls or fins 26 integrally connected to the wall (outer wall) 12 of the cylindrical body 12, with the longitudinal rod 30 positioned along the longitudinal central axis W of the cylindrical body 12. The longitudinal rod is made of iron or a ferromagnetic material. Each of the plurality of fins or partition walls 26 has a first section 26A made of a non-ferrous metal material (e.g., stainless steel, copper, or aluminum), similar to the material constituting the cylindrical body 12, which is fixed to a second section 26B of the partition wall using bolts 31, and the second section is integrally connected (e.g., by welding) to the longitudinal rod 30. The second section 26B of the partition wall is made of iron or a ferromagnetic material, as in the latter case.

[0039] The partition wall or fin 26 is slightly separated from the lid 15 so that its tip near the lid forms a chamber 34 (see Figure 7 in particular) near the lid, through which a passage 35 formed in the lid opens. The chamber 34 communicates with the passage 35, which has a gas opening 35A in the cylindrical body 12, and the opening is connected to a duct 36 equipped with a check valve 37 and a bypass solenoid valve 38. Two conduits or ducts 39 and 40 branch off from this bypass solenoid valve. The first duct 39 is equipped with a two-way solenoid valve 41, while the second duct is equipped with a solenoid valve 40A and a vacuum pump 42. The first and second ducts 39 and 40 are reconnected by a T-connector 43. Thus, the first duct 39 forms a bypass route to the second duct.

[0040] A T-type connector 43 is provided with a final duct or conduit 44 whose tip connects to a member 45 that performs oil condensation and air discharge. The member 45 that performs oil condensation and air discharge comprises a main body 46 that houses a ventilator 47 configured to draw in oil and air, and the main body is located within the final duct or conduit 44 as already described, and guides the oil-containing air to a filter / purifier 48 located within the main body 46. The air is preferably further filtered by a filter 50 and then discharged outside the member 45 that performs oil condensation and air discharge through an outlet 51 of the main body 46.

[0041] In contrast, the filter / purifier 48 itself is well known (e.g., a filter membrane, or e.g., a conical metal filter) and recovers oil present in the air drawn in through the final duct or conduit 44. The captured oil drips by gravity into a recovery tray 52 located below the filter / purifier 48. The recovery tray is connected to a tank 54 via a duct 53, as schematically shown in Figure 1, to recover the condensed oil.

[0042] A rotating magnetic field generating member 60 is provided around the cylindrical container 1 (fixed type). The rotating magnetic field enters the hollow portion 13 of the cylindrical body 12, and the rotating magnetic field forms a circuit with the longitudinal rod 30 and the second portion 26 of the ferromagnetic material of the partition wall or fin 26.

[0043] In the embodiments shown in Figures 1 to 11, the rotating magnetic field generating member 60 is configured to generate a radial rotating magnetic field within a metal chip located in the hollow portion 13 of the cylindrical container 1 by magnetic induction. This generates eddy currents within the metal chip, thereby heating it to a desired temperature, for example, 200°C to 300°C. The desired temperature is sufficient to evaporate the oil present on the surface or throughout the metal chip in the hollow portions 13A, 13B, and 13C. It should be noted that the presence of multiple partition walls or fins 26 prevents the metal chip from rotating within the hollow portion (moving due to the action of the rotating magnetic field). In this way, only the metal chip generates heat without moving due to the eddy currents. Furthermore, the partition walls also help to better propagate heat within the cylindrical container 1 and increase the heat exchange surface. Furthermore, the partition wall can also ensure good distribution of nitrogen gas introduced into the lower part of the cylindrical container, and the nitrogen gas is guided to rise relative to the cylindrical container (drawn in by the ventilator 47).

[0044] A metal chip located inside a cylindrical container 1, which is surrounded by a rotating magnetic field generating member or means, is heated uniformly by the generation of a radial magnetic field.

[0045] To explain in detail (see, for example, Figures 7 and 9), the rotating magnetic field generating member 60 is configured to detachably accommodate the cylindrical container so that when the rotating magnetic field generating member 60 heats the metal chip by magnetic induction, the cylindrical container 1 does not move and the metal chip is heated. Therefore, after the cylindrical container is accommodated, the metal chip also remains stationary within the rotating magnetic field generating member 60 during heating without substantially moving.

[0046] The rotating magnetic field generating member 60, also referred to as the "heating member 60" in the following description, comprises one or more heating sections 65 (as in the embodiment) equipped with a known brushless electric motor 250 (see Figures 10 and 11) having the same axis (or being annular), which constitutes a means or member for generating a rotating magnetic field (the brushless electric motor will be described later). Therefore, each heating section 65 has an annular shape with the same axis, overlaps with and / or touches other heating sections (see Figures 2, 4, 5, 7 and 9), and constitutes a central hole 66 configured to function as a housing section or housing chamber for the cylindrical container 1. This housing section has an axis perpendicular (as in the attached drawings) or horizontal to the plane P on which the structure consisting of the rotating magnetic field generating member 60 and the cylindrical container 1 rests when the metal chip is heated by magnetic induction. As will be described later, an annular rotor holding multiple permanent magnets is provided inside each heating section 65 and inside the corresponding brushless electric motor 250, near the location where the cylindrical container 1 is housed.

[0047] In the embodiment shown in the attached drawings (see Figure 9 in particular), a plurality of heating units 35 overlap each other axially, and each heating unit is equipped with an annular electric motor 250. Together, these constitute a rotating magnetic field generating member 60 that houses the cylindrical container 1. Within the rotating magnetic field generating member, the plurality of heating units 35 are held and connected by connecting plates (not shown) provided on both sides of each heating unit 35. Therefore, the rotating magnetic field generating member 60 has an open top surface and a robust shape (a parallelepiped, cube, or cylindrical shape suitable for the number of heating units 65 and the external shape of the heating units) in which the heating units 65 that constitute the rotating magnetic field generating member 60 overlap vertically.

[0048] Referring to Figures 9 to 11, each heating unit 65 is formed in an annular shape and includes an outer containment body 68 with a central hole 69. An electric motor 250 for each heating unit is provided in this central hole. The electric motor 250 comprises an inner rotor having a permanent magnet 71 and a stator 70. The stator 70 is electrically driven through a connector 72 protruding from the outer containment body 30. Inside the outer containment body, a cooling circuit (of the type that uses a fluid such as water or glycol) is provided around the stator 70 and is supplied through a pipe connected to a connector 73 provided inside the outer containment body 68.

[0049] In the embodiment shown in the drawings, the electric motor 250 is provided with an annular rotor 74 (which is cylindrical in the embodiment shown in the drawings) composed of at least one annular body 75. The annular body includes an annular cylindrical member 75A with an axial hole and supports a plurality of permanent magnets 76. The permanent magnets are provided with a housing portion 77 which can be suitably used as a cooling channel for the permanent magnets attached to the annular body 75. It is clear that the annular body 75 and the annular cylindrical member 75A may be configured as separate components.

[0050] The annular body, or annular rotor 74, is supported by bearing members 79 interposed between the hollow portions 80 provided near both ends of the annular body and the permanent magnet rotor 71 (see Figure 11).

[0051] Furthermore, each heating section 65 is equipped with an end cover that closes the bearing 81 and the respective end magnetic flange 82, and the end magnetic flange is configured to confine the magnetic field of the permanent magnet (seal the magnetic field within the assembly of permanent magnets 76).

[0052] However, it should be noted that the electric motor 250 used is a ring-shaped coaxial type, preferably a three-phase synchronous type with multiple magnetic poles and windings necessary to optimize torque and obtain the required output. Such a three-phase synchronous electric motor has a high performance of 95% or more. Such a three-phase synchronous electric motor is a "sensorless" type, that is, it does not have transducers to measure the rotor position and the rotation of the electric motor. Based on a calculation algorithm, the control unit of the oil removal equipment that controls the operation of the rotating magnetic field generating member 60 synchronizes all electric motors 250 within the rotating magnetic field generating member and corrects for variations in rotational speed according to temperature distribution conditions suitable for the metal chips housed in the cylindrical container 1.

[0053] Preferably, the electric motors 250 of the continuously adjacent heating units are powered so that the corresponding annular rotors 74 rotate counterclockwise to suppress the torsional torque acting on the cylindrical container 1.

[0054] The temperature of the metal tip is detected by a pin-type temperature sensor 87 housed in the hollow sections 13 (13A, 13B, and 13C) of the cylindrical container 1. The pin-type temperature sensor detects the temperature generated on the metal tip and controls the temperature of the metal tip to maintain it at an optimal value. This causes the oil present on the surface and inside of the metal tip to evaporate completely without altering the metallurgical properties of the metal tip or causing it to melt.

[0055] Temperature sensors are installed at various heights and depths throughout the metal chip. This allows for wide-ranging and effective temperature control in individual areas of the entire metal chip. The temperature sensors may be installed parallel to or perpendicular to the longitudinal central axis W of the cylindrical body.

[0056] It is clear that the temperature in individual areas of the entire metal chip will vary depending on the type of oil present in or on the surface of the metal chip, and the type of metal chip housed in the cylindrical container 1. However, the optimal temperature is generally between 200°C and 340°C.

[0057] The magnetic induction heating element 60 is highly efficient. In fact, the magnets used (neodymium, iron, boron, neodymium-iron-boron) do not require a magnetization current due to their properties.

[0058] As a variation, the rotating magnetic field generating member 60 may have an iron core and be equipped with an electric winding that generates a rotating magnetic field by electromagnetic induction instead of a permanent magnet.

[0059] The use of the oil recovery equipment 1 according to the present invention, and therefore the implementation of the method according to the present invention, begins by opening the lid 15 of the cylindrical container 1 and placing metal chips into the hollow sections 13A, 13B, and 13C of the cylindrical container 13. After closing the lid, the vacuum pump 42 is operated to create a vacuum inside the cylindrical container 1. The seal is provided by a gasket on the lid 15. The air inside the cylindrical container 1 is exhausted from the cylindrical container, passes through the second duct 40, and is discharged from the oil condensation and air discharge member 45.

[0060] After stopping the operation of the vacuum pump described above, according to the embodiment shown in the attached drawings, the solenoid valve 9 is opened to introduce nitrogen into the cylindrical container through the connecting member 17. The introduced nitrogen diffuses substantially evenly into areas 13A, 13B, and 13C of the hollow section 13 due to the action of the inert gas diffusion chamber 21 provided between the lower closing member 14 and the bottom plate 22 of the cylindrical container 1 and the shape of the bottom plate 22.

[0061] Therefore, nitrogen diffuses evenly between the metal tips. This gas avoids the adverse effects of the presence of oxygen in the cylindrical container 1 and effectively prevents the metal tips from oxidizing and altering their metallurgical properties.

[0062] When nitrogen is introduced into the cylindrical container 1, the rotating magnetic field generating member 60 is activated. In the embodiment shown in the attached drawings and described herein, each electric motor 250 of the heating unit 65 is activated. As a result, the annular rotor 74 having permanent magnets 76 (fixed to the annular rotor) rotates, as is well known. The permanent magnets generate a rotating magnetic field within the cylindrical container 1 that passes through the metal tip. This rotating magnetic field generates eddy currents within the metal tip, causing the metal tip to be trapped in the hollow portion and generate heat. As a result, the oil attached to the metal tip evaporates and is collected in the form of vapor in the chamber 34 of the cylindrical container 1 (see Figure 7).

[0063] Therefore, during the heating of the metal tip as described above, nitrogen remains introduced into the cylindrical container 1. This, for the sake of convenience, also helps to prevent oxidation of the metal tip. The inflow of nitrogen stops only after the heating cycle is complete and the metal tip has cooled (i.e., after the metal tip has substantially cooled to a temperature below which oxidation is no longer possible).

[0064] The control unit of the oil removal equipment according to the present invention continuously evaluates the temperature in areas 13A, 13B, and 13C inside the cylindrical container 1 (through a pin-type temperature sensor 87). When the temperature reaches a predetermined value (for example, 250°C), the control unit operates the rotating magnetic field generating member 60 to switch to an operating mode that maintains the temperature at the predetermined value for at least a predetermined time required for oil evaporation (set based on experiments).

[0065] Throughout the entire heating cycle, the connection between the cylindrical container 1 and the bypass path 39 is opened by the bypass solenoid valve 38, and the check valve 37 (which opens automatically due to the vacuum and nitrogen pressure generated in the bypass path 39 and duct 36 leading to the component that performs oil condensation and air discharge) is opened to discharge oil vapor from the cylindrical container along with nitrogen.

[0066] These vapors (including nitrogen) are drawn by the ventilator 47 into the oil condensation and air discharge component 45 located within the oil condensation and air discharge component body 46. The oil is captured by the filter / purifier 48, where it condenses, and is eventually collected by gravity, dripping into the recovery tray 52 and finally into the tank 54.

[0067] The oil removal equipment 1 according to the present invention can recover oil from the surface and interior of metal chips to a residual level equivalent to less than 0.4% of the initial value. Furthermore, experiments have shown that the recovered oil is pure enough to be mixed with the oil used initially and reused in machining processes.

[0068] Meanwhile, the metal chip from which the oil has been recovered is removed from the cylindrical container 1 by opening the lower closing member 14 and / or tilting the cylindrical container.

[0069] The metal tips are virtually free of residual oil and can be directly introduced into the melting furnace without harmful gases being generated from the metal bath or altering the components of the liquid phase metal.

[0070] Furthermore, the oil removal equipment according to the present invention is small in size yet has a remarkably high processing capacity per hour. For example, if the cylindrical container has a diameter of 1000 mm and a height of 1500 mm, the capacity is approximately 1 m³. 3 This is equivalent to a bronze chip weighing approximately 1500 kg, but the area occupied by the entire oil removal facility is approximately 20 to 25 m². 2 That is the case.

[0071] Moreover, the entire processing cycle, including all processing steps, can be automated.

[0072] In the embodiments of the solution shown in Figures 1 to 11, the oil removal equipment comprises a metal chip container 1 having a rotating magnetic field generating member 60 around it. That is, the rotating magnetic field is generated outside the metal chip container. Figures 12 to 18 show modified embodiments of the oil removal equipment structure according to the present invention, in which the rotating magnetic field generating member 60 is provided inside the metal chip container 1 and is arranged along the longitudinal central axis of the metal chip container. In fact, in Figures 12 to 18, the same reference numerals are used for components corresponding to those shown in Figures 1 to 11, and the metal chip container 1 has an annular shape and includes a central hollow region 100 in which the rotating magnetic field generating member 60 is housed.

[0073] More specifically, the metal chip container 1 includes a preferably circular central wall 101 that forms a central hollow region 100. Between the outer wall 27 of the metal chip container 1 and the circular central wall, partition walls or fins 26 (four in the illustrated example) are provided. These partition walls or fins 26 form four areas, denoted by reference numerals 13A, 13B, 13C, and 13D in the corresponding attached drawings, and partition the hollow portion 13.

[0074] In order to allow the rotating magnetic field to penetrate the hollow portion 13 and to achieve optimal "confinement" of the rotating magnetic field, the central wall 101 and the first portion of the partition wall or fin 26 (a portion similar to the partition wall or fin 26 in the attached drawings relating to the first embodiment of the present invention) are made of a non-ferrous metal material (for example, stainless steel). In contrast, the outer wall 27 and the second portion outer wall 27 of the partition wall or fin 26 coupled to the outer wall 27 are made of a ferromagnetic material.

[0075] With respect to Figures 12 to 18, note that the rotating magnetic field generating member 60 comprises a cylindrical body 105, and a plurality of permanent magnets 76 are provided on the outer wall 106 of the cylindrical body. The cylindrical body 105 is integrally coupled in a known manner to a rotating shaft 107 supported by a bearing 108 provided in a base 109 that detachably supports the metal chip container 1. The metal chip container is provided in a cage 110 that houses the metal chip container, and as will be described later, the cage guides the metal chip container when it is fitted onto the cylindrical body 105 or removed from the cylindrical body.

[0076] In the embodiments described, each compartment 13A to 13D is automatically supplied with nitrogen from a corresponding inert gas storage unit (not shown), and air and nitrogen are discharged from each compartment through a pipe connected to the metal chip container at the location indicated by reference numeral 112 and through a duct 36 (see Figure 12). Furthermore, the metal chip container 1 is provided with an arm 113 on its side perpendicular to the outer wall 27, so that the position of the metal chip container 1 relative to the cage 110 can be changed to allow metal chips to be loaded into and removed from the metal chip container.

[0077] The loading and unloading operations are performed using the support 115 (see Figures 17-18). The metal chip container 1 is attached to the support so that it can rotate freely about an axis X connecting the side arms 113, with its side arms supported by the posts 115 of the support.

[0078] Because of the support 115, the metal chip container 1 can be loaded with metal chips through the hopper member 15. This state is shown in Figure 17. Through the hopper member 117, the metal chip container 1 is rotated while resting on the post 116, allowing the metal chips from which the oil has been recovered to be removed (see Figure 18).

[0079] Returning to the description of the rotating magnetic field generating member, the rotating magnetic field generating member 107 is attached to a gear train 120 driven by a transmission member (for example, a belt or chain, not shown), and the transmission member is linked to a gear train 121 spline-coupled to the output shaft 122 of an electric motor 123 located on a base 108 adjacent to the cage 110 for the metal chip container. In this way, when the electric motor 123 is driven, the cylindrical body 105 rotates about axis K within the annular container 1 for the metal chip, and a rotating magnetic field is generated within the metal chip container 1.

[0080] As a modified embodiment, the rotating shaft 107 may be spline-coupled to the rotor 71 of an electric motor 250 having the same axis as described in Figures 9 to 11. This modified embodiment is schematically shown in Figure 15.

[0081] In another embodiment, a cylindrical support 105 is fixed, and an annular container 1 for metal chips rotates about axis K.

[0082] In Figures 19 and 20, components corresponding to those shown in the accompanying drawings described above are denoted by the same reference numerals, and the (fixed) metal tip container 1 is supported in a known manner on a base 109 and mounted on a turntable 200 driven by an electric motor 201 through a transmission member 202. The turntable 200 may be driven in other known manners.

[0083] The rotating base 200 supports a plurality of permanent magnets 76 positioned between the rotating base and the metal chip container 1. This configuration constitutes the heating member 60, which is a rotating magnetic field generating member.

[0084] In this way, a rotating magnetic field (generated by the rotation of the permanent magnet supported by the rotating base 200) is generated correlated between the rotating heating element 60 and the metal chip in the fixed metal chip container. This generates eddy currents that heat the metal chip and evaporate the oil.

[0085] In this embodiment as well, nitrogen is introduced into the metal tip container 1 in a known manner (through the pipe 18) before heating the metal tip, while heating the metal tip, and while removing the oil vapor (through the conduit or duct 36) for condensation in a later process.

[0086] In a modified version of this embodiment, a rotating platform is provided on the metal chip container 1, and a plurality of permanent magnets are supported between the rotating platform and the metal chip container, thereby generating a rotating magnetic field on the metal chip container.

[0087] In the embodiments described with reference to Figures 19 and 20, the rotating magnetic field is generated at the upper or lower end of the metal chip container 1 (in the positional relationship shown in Figures 19 and 20).

[0088] Therefore, the present invention provides a means for generating a magnetic field that affects metal chips (non-ferrous metals such as nickel, cupronickel, magnesium, bronze, and aluminum, and / or alloys thereof) (a plurality of permanent magnets rotating around an axis, a fixed electromagnetic coil or winding through which current flows). In short, relative movement is created between the heating element 60 and the metal chip container 1 so that the metal chips present in the metal chip container 1 are exposed to a rotating magnetic field (in relation to the metal chips). As already described, this situation is achieved by moving the permanent magnet or heating element of the magnetic field generator and stationary the metal chip container 1 (this embodiment is referred to as "movable heating element and fixed container" and is a preferred embodiment), or by rotating the metal chip container 1 relative to the permanent magnet or heating element 60 of the magnetic field generator (this embodiment is referred to as "fixed heating element and rotating container").

[0089] The rotating magnetic field generated between the movable heating element and the fixed container passes through the metal chip, and the induced current circulating within the metal chip heats the metal chip in a short time. This heating is controlled using the temperature sensor 87.

[0090] In the final step of implementing the method according to the present invention as described above, the oil on or inside the metal tip is removed and recovered through an oil condensation and air discharge member as described above.

[0091] The processing method according to the present invention can be performed with small equipment and correspondingly low energy consumption, but with a large processing capacity. The equipment according to the present invention allows for high processing capacity per hour when processing metal chips.

[0092] Although various embodiments of the present invention have been described, various modifications are possible within the scope of protection of the present invention, which has the structural features described in the claims below.

Claims

1. A method for removing oil from metal chips derived from machining processes, wherein the metal chips are housed in a container (1), The metal chip is affected, generating a magnetic field that passes through it, causing relative motion between the magnetic field and the metal chip, thereby heating the metal chip. This heating causes the oil in the container (1) to evaporate, Next, the oil is drained from the container. The discharged oil is condensed and collected in the recovery tank (54). A method characterized by removing the metal chip from which the oil has been removed from the container (1).

2. The method according to claim 1, characterized in that the magnetic field is generated in a rotating manner, and the metal chip is positioned in a stationary state within the container (1).

3. The method according to claim 1, characterized in that the magnetic field is stationary and the container (1) is rotated within the magnetic field.

4. The method according to claim 2 or 3, characterized in that the magnetic field is generated outside the container (1).

5. The method according to claim 4, characterized in that the magnetic field is generated around the container (1) or at either the upper or lower end of the container.

6. The method according to claim 2 or 3, characterized in that the magnetic field is generated at an internal location within the container.

7. The method according to claim 1, characterized in that a negative pressure or vacuum state is created inside the container (1), and then an inert gas such as nitrogen is introduced into the container (1) before the magnetic field is generated.

8. The method according to claim 7, characterized in that the nitrogen is introduced into the container (1) even while the metal chip is being heated until the cooling of the metal chip is completed.

9. During the generation of the magnetic field, the temperature inside the container (1) is controlled. The method according to claim 1, characterized in that when the temperature reaches a predetermined value, the generation of the magnetic field is stopped or adjusted so that the temperature does not exceed the predetermined value, thereby keeping the temperature constant for a predetermined time.

10. The method according to claim 1, characterized in that the metal chip does not rotate about the longitudinal axis (W) of the container (1) while exposed to the magnetic field.

11. Equipment for removing oil from metal chips derived from machining processes, The metal chip is housed in container (1), The aforementioned equipment includes a magnetic field generating member (60) provided in the container for the metal chip, Relative movement occurs between the container (1) and the generated magnetic field. In a device in which the magnetic field penetrates the metal chip inside the container, and the oil attached to the metal chip evaporates due to heating caused by the generation of the magnetic field, A device (47) is provided that extracts the oil vapor generated in the container (1) and sends the oil vapor to a condenser (45) configured to condense the oil vapor. The tank (54) for recovering the condensed oil is connected to the condenser (45) to receive and store the condensed oil. The container (1) is a hollow portion (13) comprising a hollow portion having at least two partition walls (26) that can divide the hollow portion into at least two areas (13A, 13B, 13C, 13D) capable of stably accommodating the metal chip to be placed in the magnetic field, The partition wall (26) is characterized in that it prevents the metal chips contained in the container from moving about the longitudinal axis (W) of the container, which is generated by the rotation of the magnetic field.

12. The partition wall (26) comprises first and second parts (26A, 26B) that are connected to each other and are made of different materials that exhibit different behaviors when exposed to a magnetic field. The apparatus according to claim 11, characterized in that the first and second parts (26A, 26B) are connected to the outer wall (27) of the cylindrical body (12) of the container and to a part provided inside the cylindrical body along the longitudinal axis (W) of the cylindrical body, respectively.

13. The apparatus according to claim 11, characterized in that the magnetic field generating member (60) is provided with a permanent magnet or an electric winding to generate the magnetic field by electromagnetic induction.

14. The apparatus according to claim 11, characterized in that the magnetic field generating member (60) is provided inside or outside the container (1) that houses the metal chip.

15. The container (1) comprises a cylindrical body (12), The magnetic field generating member (60) comprises at least one annular portion (65) having an annular electric motor (250) having the same axis around the cylindrical body (12) of the container. An annular electric motor (250) having the same axis is provided with an annular rotor (74) comprising an annular body (75) that supports a plurality of permanent magnets (76). The annular rotor (74) is driven to rotate around the container (1) by the operation of an annular electric motor (250) having the same axis, and generates a rotating magnetic field to which the cylindrical body (1) is exposed by the action of the permanent magnet (76). The apparatus according to claim 14, characterized in that the container is fixed and contains the metal chips.

16. The container (1) is an annular shape and has a central wall (101) that forms a central hollow region (100) for housing the magnetic field generating member (60). The magnetic field generating member (60) is a cylindrical body (105) comprising a cylindrical body on which a plurality of permanent magnets (76) are provided on the outer wall (106), The apparatus according to claim 14, characterized in that the cylindrical body (105) is rotationally driven within the central hollow region (100) of the container, or the container is rotationally driven around a central support (105) that supports the permanent magnet (76).

17. The container (1) is provided either above or below the magnetic field generating member (60). The apparatus according to claim 14, characterized in that relative movement occurs between the container and the magnetic field generating member.

18. Each first portion (26A) of the partition wall (26) and the outer wall (27) of the cylindrical body (12) provided within the magnetic field generating member (60) are formed of a non-ferrous magnetic material. The portion (30) provided along the longitudinal axis (W) and the second portion (26B) of each of the partition walls (26) are formed of a ferromagnetic material. The equipment according to claim 12 or 15, characterized in that the portion (30) provided along the longitudinal axis (W) is rod-shaped.

19. The portion (100) provided along the longitudinal axis (W) of the cylindrical body (12) of the container (1) is the central hollow region (100) of the annular-shaped container (1), Each second portion (26B) of the partition wall (26) is integrally connected to the central portion (101) of the container that forms the central hollow region (100) where the magnetic field generating member is provided. The apparatus according to claim 12, characterized in that each of the second portions (26B) of the partition wall and the central portion (101) are formed of a non-ferrous magnetic material, while each of the first portions (26A) of the partition wall (26) and the outer wall (27) of the container are formed of a ferromagnetic material.

20. A storage container (19) for an inert gas such as nitrogen is connected to the container (1) that houses the metal chips, A vacuum pump (42) configured to generate negative pressure inside the container before generating the magnetic field, the vacuum pump being connected to the container, Equipped with, The apparatus according to claim 11, characterized in that the inert gas is evenly distributed to the metal chips.

21. The equipment according to any one of claims 11 to 20, characterized in that it has at least one of the following structural features. Multiple temperature sensors (87) are provided inside the container of the metal chip, and the multiple temperature sensors are provided at different heights and depths within the metal chip. The device (47) for discharging oil vapor includes an aspirator connected to the container (1) through a duct, and the duct is connected to a conduit (40) in which the vacuum pump (42) is installed and a bypass conduit (39) of the conduit (40) in which the vacuum pump is installed. The magnetic field generating member (60) includes a permanent magnet, a coil, or an electric winding to generate a rotating magnetic field by electromagnetic induction.

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