Processing debris removal device and pH adjustment method

Abstract

Reduce carbon dioxide usage. [Solution] A processing debris removal device is provided, comprising: a water tank to be treated; a carbon dioxide supply unit that supplies carbon dioxide to the water to be treated stored in the water tank to be treated; a process tank that stores the water to be treated supplied from the water tank to be treated; a removal unit that removes processing debris from the water to be treated stored in the process tank to produce purified water; a purified water tank that stores the purified water supplied from the process tank; a first supply unit that supplies to the water to be treated a fluid in the purified water tank that contains carbon dioxide that was dissolved or mixed in the purified water but has been separated as a gas from the purified water; a water to be treated pH measuring unit that measures the pH of the water to be treated stored in the water to be treated tank; and a controller, wherein the controller decides whether or not to supply the fluid in the purified water tank to the water to be treated by the first supply unit based on the pH of the water to be treated in the water to be treated tank measured by the water to be treated pH measuring unit.

Description

[Technical Field]

[0001] The present invention relates to a processing debris removal device that removes processing debris contained in water to be treated, and a pH adjustment method that adjusts the pH of a processing debris removal device's .... [Background technology]

[0002] In processing equipment such as grinding equipment and cutting equipment that processes workpieces such as semiconductor wafers, processing water such as pure water is supplied to the processing area to remove heat and processing debris generated in the processing area during processing of the workpiece. Therefore, the wastewater discharged from the processing equipment contains processing debris.

[0003] Therefore, in a processing debris removal device that removes processing debris from wastewater and reuses the water, a technique has been proposed in which processing debris is removed from wastewater by electrophoresis (see, for example, Patent Document 1).

[0004] Furthermore, in a processing debris removal device, a technique has been proposed in which carbon dioxide is supplied to the wastewater to increase the electrical conductivity of the wastewater in order to remove processing debris from the wastewater by electrophoresis (see, for example, Patent Document 2).

[0005] However, not all of the carbon dioxide supplied to the wastewater is dissolved in the wastewater, and the carbon dioxide that does not dissolve in the wastewater is usually discharged from the processing debris removal device and lost. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-146418 [Patent Document 2] Japanese Patent Publication No. 2022-89048 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above problems, and aims to reduce the amount of carbon dioxide used by effectively utilizing the carbon dioxide supplied to wastewater. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a processing debris removal device for removing processing debris contained in water to be treated, the device comprising: a water tank for storing the water to be treated; a carbon dioxide supply unit for supplying carbon dioxide to the water to be treated stored in the water tank for treatment; a process tank for storing the water to be treated delivered from the water tank for treatment; a removal unit having at least a pair of electrodes provided in the process tank, which uses electrophoresis to retain the processing debris contained in the water to be treated stored in the process tank on one of the at least a pair of electrodes, thereby removing the processing debris from the water to be treated and producing purified water; a first supply unit that supplies the fluid in the purified water tank containing carbon dioxide that was dissolved or mixed in the purified water but has now separated as a gas from the purified water to the water to be treated tank; a water to be treated pH measuring unit that measures the pH of the water to be treated stored in the water to be treated tank; and a controller, wherein the controller determines whether or not to supply the fluid in the purified water tank to the water to be treated by the first supply unit based on the pH of the water to be treated in the water to be treated tank measured by the water to be treated pH measuring unit.

[0009] Preferably, the processing debris removal device further includes a disposal section for disposing of the fluid in the purified water tank, and the first supply section has a switching section for switching the destination of the fluid to the treated water tank or the disposal section, and the controller controls the switching section based on the pH of the treated water in the treated water tank measured by the treated water pH measuring section, thereby switching whether the fluid in the purified water tank is to be supplied to the treated water tank or the disposal section.

[0010] Also, preferably, the processing debris removal device further includes a gas amount measuring unit that measures the amount of gas in the purified water tank, and the controller determines whether or not to supply the fluid in the purified water tank to the treated water tank by the first supply unit based on the amount of gas measured by the gas amount measuring unit.

[0011] Preferably, the processing debris removal device further includes a second supply unit that supplies the purified water in the purified water tank to the treated water tank via a second path different from the first path along which the first supply unit supplies the fluid from the purified water tank to the treated water tank, and a purified water pH measuring unit that measures the pH of the purified water stored in the purified water tank, and the controller causes the second supply unit to supply the purified water to the treated water tank when the pH of the purified water satisfies a predetermined condition.

[0012] According to another aspect of the present invention, in a processing debris removal device for removing processing debris contained in water to be treated, a pH adjustment method for adjusting the pH of a water tank in which the water to be treated is stored includes a first pH adjustment step of supplying carbon dioxide to the water to be treated stored in the water tank to adjust the pH of the water to be treated; a purified water production step of generating purified water by using electrophoresis to remove the processing debris contained in the water to be treated, the pH of which has been adjusted by the first pH adjustment step; a water storage step of supplying the purified water to an airtight purified water tank and storing it therein; A pH adjustment method is provided, which includes a pH measurement step of measuring the pH of the water to be treated in a water tank, and a second pH adjustment step of supplying a fluid containing carbon dioxide that was dissolved or mixed in the purified water stored in the purified water tank but has been separated as a gas from the purified water to the water to be treated in the tank if the pH of the water to be treated in the pH measurement step is higher than a predetermined value, but not supplying the fluid to the water to be treated stored in the tank if the pH of the water to be treated in the pH measurement step is lower than the predetermined value. [Effects of the Invention]

[0013] A processing debris removal device according to one embodiment of the present invention comprises a carbon dioxide supply unit that supplies carbon dioxide to water to be treated stored in a water tank to be treated, a process tank that stores the water to be treated supplied from the water tank to be treated, a removal unit that removes the processing debris from the water to be treated to produce purified water, an airtight purified water tank that stores the purified water supplied from the process tank, and a first supply unit that supplies a fluid containing carbon dioxide in the purified water tank that was dissolved or mixed in the purified water but has separated as a gas from the purified water to the water tank to be treated.

[0014] By having the first supply unit supply a fluid containing carbon dioxide from the purified water tank to the treated water tank, the carbon dioxide supplied to the treated water can be effectively utilized, thereby reducing the amount of carbon dioxide used in the carbon dioxide supply unit compared to when no fluid is supplied to the treated water tank.

[0015] The processing debris removal device also includes a treated water pH measuring unit that measures the pH of the treated water stored in the treated water tank, and a controller, and the controller decides whether or not to supply the fluid containing carbon dioxide in the purified water tank to the treated water tank based on the pH of the treated water in the treated water tank measured by the treated water pH measuring unit.

[0016] If the pH of the water in the tank is strong acidity, for example, less than 3.0, the processing waste contained in the water will aggregate and tend to settle in the tank, making it difficult to remove the processing waste by electrophoresis in the process tank. Note that the processing waste removed in the process tank may be reused as material, so if it cannot be removed in the process tank, the processing waste will not be reused.

[0017] In response to this, the controller controls the first supply unit to supply the fluid containing carbon dioxide in the purified water tank to the water tank based on the pH of the water in the tank (for example, when the pH is relatively high, such as 4.0 or higher). This prevents the processing waste from flocculating and settling in the tank.

[0018] In another aspect of the pH adjustment method of the present invention, carbon dioxide is supplied to the water to be treated stored in a water tank to adjust the pH of the water to be treated (first pH adjustment step), the processing debris contained in the pH-adjusted water to be treated is removed using electrophoresis to produce purified water (purified water production step), the purified water is supplied to an airtight water tank to be treated and stored (storage step), the pH of the water to be treated in the water tank to be treated is measured (pH measurement step), and if the pH of the water to be treated is above a predetermined value, a fluid containing carbon dioxide that was dissolved or mixed in the purified water stored in the water tank to be treated but has been separated as a gas from the purified water is supplied to the water to be treated stored in the water tank to adjust the pH, but if the pH of the water to be treated is below the predetermined value, the fluid containing carbon dioxide is not supplied to the water to be treated stored in the water tank to be treated (second pH adjustment step).

[0019] In this pH adjustment method, by supplying a fluid containing carbon dioxide from the purified water tank to the treated water tank, the carbon dioxide supplied to the treated water can be effectively utilized, thereby reducing the amount of carbon dioxide used in the carbon dioxide supply section compared to when no fluid is supplied to the treated water tank.

[0020] In addition, provided that the pH of the water to be treated is above a predetermined value, a fluid containing carbon dioxide that was dissolved or mixed in the purified water stored in the purified water tank but has been separated as a gas from the purified water is supplied to the water to be treated stored in the treated water tank, thereby preventing processing debris from coagulating and settling in the treated water tank. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a diagram showing a grinding device and a machining chip removal device. [Figure 2] FIG. 2 is a block diagram of a processing debris removal device. [Figure 3] FIG. 1 is a flow diagram of a pH adjustment method in a processing debris removal device. DETAILED DESCRIPTION OF THE INVENTION

[0022] An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a diagram showing a grinding apparatus 2 and a machining chip removal apparatus 30. In this embodiment, the grinding apparatus 2 is shown as an example of a machining apparatus that machines a workpiece 11.

[0023] However, instead of the grinding device 2, a cutting device for cutting the workpiece 11 with a cutting blade, a bit cutting device (i.e., a surface planer) for cutting and flattening one side of the workpiece 11 using a bit cutting tool, etc. may be used.

[0024] The grinding device 2 shown in Fig. 1 includes a rectangular parallelepiped base 4. The X-axis, Y-axis, and Z-axis shown in Fig. 1 are perpendicular to one another. The Z-axis is parallel to the up-down direction (i.e., a direction parallel to the vertical direction). The base 4 has an opening 4a, and a disk-shaped chuck table 6 is provided above the opening 4a.

[0025] The chuck table 6 has a disk-shaped frame made of non-porous ceramics. A disk-shaped recess with a diameter smaller than the outer diameter of the frame is provided in the center of the frame, and a disk-shaped porous plate made of porous ceramics is provided in this recess.

[0026] A negative pressure is transmitted to the porous plate from a suction source (not shown) such as a vacuum pump. The upper surfaces of the frame and the porous plate are substantially flush with each other and function as a holding surface 6a that holds the workpiece 11 by suction. A cylindrical rotating shaft 6b is provided at the bottom of the frame, and the rotating shaft 6b rotates by power transmitted from a rotation drive source 8 such as a servo motor.

[0027] A grinding unit 10 is provided above the chuck table 6. The grinding unit 10 is configured to be movable along the Z axis by a Z-axis direction movement mechanism (not shown) having a motor and a ball screw.

[0028] The grinding unit 10 has a cylindrical spindle housing 12. A part of a spindle 14 is accommodated in the spindle housing 12 so as to be rotatable by an air bearing (hydrostatic air bearing).

[0029] A stator (not shown) that constitutes a motor is provided within the spindle housing 12, and a cylindrical spindle 14 that is partially provided within the spindle housing 12 functions as a rotor that constitutes the motor.

[0030] The lower end of the spindle 14 protrudes downward below the lower end of the spindle housing 12, and the center of the upper surface of a disk-shaped mount 16 is fixed to the lower end of the spindle 14. An annular grinding wheel 18 is attached to the lower surface of the mount 16, concentrically arranged with the mount 16, using bolts (not shown) or the like.

[0031] The grinding wheel 18 has an annular base. A plurality of grinding stones are arranged at approximately equal intervals around the circumference of the base on the bottom surface of the base. When the spindle 14 is rotated, the grinding wheel 18 rotates around the spindle 14 as the rotation axis.

[0032] When grinding the workpiece 11, the chuck table 6 and the grinding wheel 18 are rotated in a predetermined direction, and the grinding unit 10 is lowered along the Z axis at a predetermined speed, thereby grinding the workpiece 11.

[0033] When grinding the workpiece 11, grinding water 15 such as pure water is supplied to the contact area between the movement trajectory of the bottom surfaces of the multiple grinding wheels and the workpiece 11, for example, from a grinding water supply nozzle (not shown).

[0034] During grinding, processing waste (grinding waste in this example) 13 is generated from the workpiece 11. When the surface to be ground of the workpiece 11 is one side of a silicon single crystal substrate, silicon powder is generated as processing waste 13. The used grinding water 15 contains this processing waste 13.

[0035] A cover 20 having a rectangular upper surface is provided on the bottom of the frame of the chuck table 6. A water case 22 is provided on the bottom of the cover 20 to receive used grinding water 15 that drops downward from the outer periphery of the cover 20.

[0036] 1 is provided along the outer periphery of the cover 20 and has a rectangular ring shape in the XY plane. A drain outlet 24 is provided in the bottom plate of the water case 22. The drain outlet 24 is connected to a water tank 32 of the processing debris removal device 30 via a pipe 26.

[0037] 1, the pipe section 26 is shown by a line for convenience. The used grinding water 15 flows from the water case 22 into the untreated water tank 32 at a flow rate of, for example, 30 L / min. The capacity of the untreated water tank 32 is, for example, 50 L, and the machining debris removal device 30 treats the used grinding water 15 at a processing speed that does not cause the untreated water tank 32 to overflow.

[0038] A specific example of the treatment in the machining debris removal device 30 is the removal of machining debris 13 from used grinding water 15. Therefore, hereafter in this specification, the used grinding water 15 containing the machining debris 13 will be referred to as water to be treated 17. The water to be treated 17 is temporarily stored in a water to be treated tank 32. In Figure 1, an example of the liquid level of the water to be treated 17 in the water to be treated tank 32 is indicated by a dashed line.

[0039] A diffuser (not shown) for diffusing gaseous carbon dioxide is provided inside the treated water tank 32. The diffuser is connected to one end of a pipe section 34. The other end of the pipe section 34 is connected to a container 36a containing carbon dioxide gas.

[0040] A valve 34a such as an electromagnetic valve is provided in the pipe section 34. The diffuser, pipe section 34, container 36a, valve 34a, etc. function as a carbon dioxide supply section 36 that supplies carbon dioxide 36b to the water to be treated 17. The carbon dioxide supply section 36 may further include a flow meter, a filter, a dryer, etc.

[0041] Carbon dioxide 36b is supplied at a flow rate of 10 L / min under normal temperature and pressure conditions to the water to be treated 17 stored in the water to be treated tank 32. At least a portion of the supplied carbon dioxide 36b dissolves in the water to be treated 17, and therefore the electrical conductivity of the water to be treated 17 can be increased compared to when the carbon dioxide 36b is not dissolved in the water to be treated 17.

[0042] Increasing the electrical conductivity of the water to be treated 17 makes it easier to remove the processing debris 13 from the water to be treated 17 in the removal unit 44, which will be described later. In this embodiment, carbon dioxide 36b is dissolved to increase the electrical conductivity and adjust the pH of the water to be treated 17 to 3.0 or more and 5.0 or less (for example, 4.0).

[0043] Incidentally, when water with dissolved carbon dioxide gas (i.e., carbonated water) is stored in the container 36a, instead of using a diffuser, the carbonated water (i.e., carbon dioxide 36b) may be supplied from the container 36a to the treated water tank 32. In this case, the pipe section 34, the container 36a, the valve 34a, etc. function as the carbon dioxide supply section 36.

[0044] The tank 32 for treated water is provided with a pH measuring unit 38 for measuring the pH of the water to be treated 17 stored in the tank 32 for treated water. The pH measuring unit 38 for treated water in this embodiment is a pH measuring instrument, and includes a probe 38a including electrodes and a pH measuring main body 38b having a predetermined circuit (not shown) electrically connected to the probe 38a and converting the electrical signal measured by the probe 38a into pH.

[0045] The treated water pH measuring unit 38 may transmit the electrical signal measured by the probe 38a to the controller 90 (described later) without converting it to pH. The treated water pH measuring unit 38 may also have an electrical conductivity meter (not shown), and may measure electrical conductivity instead of measuring pH, and transmit a signal corresponding to the measured electrical conductivity to the controller 90.

[0046] In this case, the controller 90 converts the electrical conductivity into pH to determine the pH of the water to be treated 17 in the water to be treated tank 32, but the pH of the water to be treated 17 is actually measured by the water to be treated pH measuring unit 38.

[0047] The water to be treated 17 is supplied to the process tank 42 via a pipe section 40. In Fig. 1, the pipe section 40 is shown by a line for convenience. In the example shown in Fig. 1, a portion of the pipe section 40 is connected to the top plate of the water to be treated tank 32, but it may also be connected to a side plate or a bottom plate of the water to be treated tank 32.

[0048] The pipe section 40 is provided with a pump 40a such as a turbo pump, a positive displacement pump, or an ejector, and the process tank 42 temporarily stores the water to be treated 17 delivered from the water to be treated tank 32 by the pump 40a.

[0049] The process tank 42 is a rectangular parallelepiped container with an open top. In this embodiment, the process tank 42 is disposed above the untreated water tank 32, but may be disposed in parallel with the untreated water tank 32 at the bottom of the processing debris removal device 30.

[0050] The process tank 42 is provided with a removal section 44 for removing the processing debris 13 from the water to be treated 17 using electrophoresis to produce purified water 19. The removal section 44 has a plurality of holding plates 46.

[0051] Each of the multiple holding plates 46 is a flat metal plate and functions as an electrode. The multiple holding plates 46 are arranged at predetermined intervals inside the process tank 42. For ease of explanation, three holding plates 46 are shown in Figure 1, but the number of holding plates 46 may be four or more.

[0052] The holding plate 46 is made of, for example, stainless steel, but may also be made of a precious metal such as copper (Cu), silver (Ag), platinum (Pt), gold (Au), etc. The holding plate 46 is connected to the positive electrode of a DC power supply (not shown) when removing the processing debris 13.

[0053] At least a portion of each holding plate 46 is immersed in the water to be treated 17. If the processing debris 13 is mainly composed of silicon, the processing debris 13 will be negatively charged in the water to be treated 17. Therefore, when the positive electrode of a DC power supply is connected to the holding plate 46 and the holding plate 46 functions as a positive electrode, the processing debris 13 moves within the water to be treated 17 and is attracted to the holding plate 46.

[0054] A rectangular parallelepiped housing 48 having a cavity is provided between two adjacent holding plates 46. For convenience of explanation, two housings 48 are shown in Fig. 1, but the number of housings 48 may be three or more.

[0055] The housing 48 has a top portion 48a and a bottom portion 48b each having a rectangular plate shape, a pair of first side portions each having a rectangular plate shape, and a pair of second side portions 48c having a mesh shape. The top portion 48a, the bottom portion 48b, the pair of first side portions, and the pair of second side portions 48c define an internal cavity of the housing 48.

[0056] The second side portion 48c is a metal mesh and is formed of, for example, stainless steel, but may also be formed of a precious metal such as copper, silver, platinum, gold, etc. The second side portion 48c is connected to the negative electrode of a DC power supply (not shown) when removing the processing debris 13.

[0057] When the processing debris 13 is mainly composed of silicon, the processing debris 13 is negatively charged in the water to be treated 17, and therefore when the second side portion 48c is negative, the processing debris 13 receives a repulsive force from the second side portion 48c.

[0058] The treated water 17, excluding the processing waste 13 that cannot pass through the mesh of the second side portion 48c, passes through the mesh of the second side portion 48c and is extracted as purified water 19 into the pipe portion 62 from the outlet 48d provided on the top 48a of the housing 48.

[0059] In this way, in the removal section 44, the holding plate 46 (i.e., the positive electrode) and the second side portion 48c (i.e., the negative electrode) constitute a pair of electrodes provided in the process tank 42, and the holding plate 46 (i.e., one of the pair of electrodes) holds at least some of the processing debris 13, thereby removing the processing debris 13 contained in the treated water 17.

[0060] In this specification, purified water 19 refers to liquid from which processing debris 13 has been removed using electrophoresis from the water to be treated 17, and does not necessarily refer to water suitable for human consumption. Therefore, purified water 19 may contain processing debris 13 that cannot be removed using electrophoresis in the removal unit 44.

[0061] Incidentally, a pair of protrusions 46a are provided on the upper portion of each holding plate 46, protruding above the top surface 42a of the process tank 42. The pair of protrusions 46a are aligned in the depth direction of the page, and only one of the pair of protrusions 46a, located on the near side, is shown in Fig. 1.

[0062] The chips 13 that have adhered to the holding plate 46 after the predetermined period of time of energization are scraped off by a scraping mechanism 52 provided adjacent to the process tank 42. When scraping off the chips 13 from the holding plate 46, the power supply from the DC power supply is stopped, and then the moving mechanism 50 moves the holding plate 46 to the scraping mechanism 52.

[0063] At this time, the processing waste 13 contains moisture (i.e., sludge), and is held in close contact with the holding plate 46 by cohesive force even when no voltage is supplied to the holding plate 46 from the DC power supply.

[0064] The movement mechanism 50 has a locking portion 50a including a pair of pins that are inserted into the protrusions 46a, respectively. The pair of pins in the locking portion 50a are configured to move toward and away from each other by an actuator (not shown).

[0065] The locking portion 50a is configured to be movable along the height direction of the process tank 42 by a height direction movement mechanism 50b. Furthermore, the height direction movement mechanism 50b is configured to be movable along the horizontal direction by a horizontal direction movement mechanism 50c.

[0066] Although the height direction movement mechanism 50b and the horizontal direction movement mechanism 50c are simplified in FIG. 1, the height direction movement mechanism 50b and the horizontal direction movement mechanism 50c each include a motor, a ball screw, a linear motor, etc.

[0067] The moving mechanism 50 brings the pair of pins in the locking portion 50a close together and inserts them into the pair of protrusions 46a of the holding plate 46, and then lifts the holding plate 46 out of the process tank 42 and moves it to directly above the scraping mechanism 52.

[0068] The scraping mechanism 52 has a box body 52a with an open bottom. A slit 52b is formed at the top of the box body 52a, into which the holding plate 46 can be inserted. The moving mechanism 50 moves the holding plate 46 directly above the scraping mechanism 52, and inserts almost the entire holding plate 46 into the slit 52b.

[0069] At this time, the moving mechanism 50 moves the protrusion 46a above the top surface of the box body 52a, and positions the area of ​​the holding plate 46 that was immersed in the water to be treated 17 below the top surface of the box body 52a.

[0070] A pair of plate portions 52c is provided on the top of the box body 52a so as to sandwich the slit 52b when the top surface of the box body 52a is viewed from above. The pair of plate portions 52c can move toward or away from each other by an actuator (not shown).

[0071] After the holding plate 46 is inserted into the slit 52b, the pair of plate portions 52c is operated to bring the tips of the pair of plate portions 52c into contact with the holding plate 46. By raising the holding plate 46 in this state, the pair of plate portions 52c physically scrapes off the processing debris 13 from the holding plate 46.

[0072] The scraped-off chips 13 fall below the scraping mechanism 52 and are then received by the drying mechanism 54. The drying mechanism 54 has a box-shaped housing 56 with an open bottom. An inlet 56a is provided at the top of the housing 56, through which the chips 13 scraped off from the holding plate 46 fall.

[0073] A belt conveyor 58 is provided inside the housing 56. The processing waste 13 that has passed through the carry-in entrance 56a is received by the belt conveyor 58. An exit 56b through which the dried processing waste 13 passes is provided at the bottom of the housing 56.

[0074] The belt conveyor 58 is inclined from the carry-in entrance 56a toward the carry-out exit 56b. The processing waste 13 that has fallen onto the belt conveyor 58 is dried by heat from a heater (not shown) provided on the belt conveyor, and is transported by the belt conveyor 58.

[0075] The belt conveyor 58 transports the dried chips 13 toward the head pulley, causing the chips 13 to fall into the discharge port 56b due to their own weight. A collection box 60, which is a bottomed box with an open top, is provided directly below the discharge port 56b. The chips 13 that have fallen into the discharge port 56b are collected in the collection box 60.

[0076] Here, we will explain the purified water 19 taken out from the outlet 48d of the housing 48 provided in the process tank 42 and its treatment. The above-mentioned pipe section 62 connects the outlet 48d provided in the top 48a of the housing 48 to the purified water tank 64. In Figure 1, the pipe section 62 is conveniently shown as a line, and the outlet 62a of the pipe section 62 is conveniently shown as a circle.

[0077] The purified water tank 64 is an airtight tank that stores the purified water 19 supplied from the process tank 42. The purified water 19 is supplied from the process tank 42 to the purified water tank 64 by a first pump 74 of a first supply unit 70 or a second pump 84 of a second supply unit 80, which will be described later.

[0078] When the machining debris removal device 30 has been operated for a certain period of time, the purified water tank 64 contains purified water 19, and in addition, carbon dioxide 36b, which had been dissolved or mixed in the purified water 19 but has separated as a gas from the purified water 19, remains above the purified water 19 in the purified water tank 64.

[0079] In addition, since the purified water tank 64 is airtight, the carbon dioxide 36b in the purified water tank 64 does not leak out and disappear from the purified water tank 64. The purified water 19 and the first pump 74 present in the pipe section 62 also contribute to preventing the carbon dioxide 36b from leaking out.

[0080] When the first pump 74 discharges the fluid 21 containing carbon dioxide 36b from the purified water tank 64 to the outside of the purified water tank 64, purified water 19 equivalent to the volume discharged from the purified water tank 64 is newly sucked into the purified water tank 64 through the outlet 62a.

[0081] Furthermore, when the second pump 84 discharges the purified water 19 from the purified water tank 64 to the outside, the purified water 19 equivalent to the volume discharged from the purified water tank 64 is newly sucked into the purified water tank 64 through the outlet 62a.

[0082] The purified water tank 64 is provided with a purified water pH measurement unit 66 for measuring the pH of the purified water 19 stored in the purified water tank 64. The purified water pH measurement unit 66 of this embodiment is a pH measuring device, and includes a probe 66a including electrodes and a pH measurement main body 66b having a predetermined circuit (not shown) electrically connected to the probe 66a and converting the electrical signal measured by the probe 66a into pH.

[0083] The purified water pH measuring unit 66 may transmit the electrical signal measured by the probe 66a to the controller 90 without converting it into pH. The purified water pH measuring unit 66 may also have an electrical conductivity meter (not shown), and may measure electrical conductivity instead of measuring pH, and transmit a signal corresponding to the measured electrical conductivity to the controller 90.

[0084] In this case, the controller 90 converts the electrical conductivity into pH to identify the pH of the purified water 19 in the purified water tank 64, but the pH of the purified water 19 is actually measured by the purified water pH measuring unit 66.

[0085] The purified water tank 64 is also provided with a gas amount measuring unit 68 that measures the amount of gas in the purified water tank 64. The gas amount measuring unit 68 of this embodiment is a level meter (i.e., a level sensor) that can continuously measure the liquid level of the purified water 19 in the height direction 64z of the purified water tank 64.

[0086] Since the maximum liquid level of the purified water 19 is known depending on the capacity of the purified water tank 64, the controller 90 can calculate the amount of gas in the purified water tank 64 from the liquid level of the purified water 19 measured by the level meter.

[0087] However, the gas amount measuring unit 68 may also have a plurality of level switches (i.e., level sensors) arranged discretely along the height direction 64z, a weight sensor that measures the weight of the purified water tank 64 according to the amount of purified water 19, or a capacitance sensor that measures the distance from the top plate of the purified water tank 64 to the liquid level of the purified water 19.

[0088] The capacity of the purified water tank 64 is, for example, 10 L, and when the amount of gas (in this example, mainly carbon dioxide 36b) in the purified water tank 64 exceeds an upper limit value (for example, 1.0 L), fluid 21 is supplied from the purified water tank 64 to the outside of the purified water tank 64.

[0089] However, in order to prevent gas from being supplied as fluid 21 to the outside of the purified water tank 64 from a purified water tank 64 that has no purified water 19 or is almost empty, the fluid 21 may be supplied to the outside of the purified water tank 64 on the condition that the amount of gas in the purified water tank 64 measured by the gas amount measuring unit 68 has increased beyond a predetermined lower limit value.

[0090] In this specification, the fluid 21 containing carbon dioxide 36b mainly contains gaseous carbon dioxide 36b, but may also contain liquid or gaseous purified water 19, or the entire fluid 21 may be gaseous carbon dioxide 36b.

[0091] A pipe 64a is attached to the top plate of the purified water tank 64, and the pipe 64a is connected to a first supply unit 70. The fluid 21 is supplied by the first supply unit 70 from the purified water tank 64 to the treated water tank 32 or the waste unit 72 via the pipe 64a.

[0092] The first supply unit 70 has a first pump 74 such as a turbo pump, a positive displacement pump, an ejector, etc. The first supply unit 70 further has a three-way valve (switching unit) 76 that switches the destination of the fluid 21 between the treated water tank 32 or the waste unit 72.

[0093] The three-way valve 76 of this embodiment is an electrically operated valve whose opening and closing is controlled by a controller 90, which will be described later. One end of a pipe section 64b, the other end of which is connected to the bottom of the tank for water to be treated 32, is connected to the three-way valve 76. However, the one end of the pipe section 64b is not limited to this form and may be connected to the side or top surface of the tank for water to be treated 32.

[0094] When the purified water tank 64 and the tank for water to be treated 32 are connected via the pipe section 64a and the pipe section 64b, the fluid 21 containing the carbon dioxide 36b is fed from the purified water tank 64 to the tank for water to be treated 32.

[0095] This allows the carbon dioxide 36b supplied to the water to be treated 17 to be used effectively, so that the amount of carbon dioxide 36b used in the carbon dioxide supply unit 36 ​​can be reduced compared to when the fluid 21 is not supplied to the water to be treated tank 32.

[0096] The pipes 64a and 64b form a first path along which the first supply unit 70 supplies the fluid 21 from the purified water tank 64 to the treated water tank 32. The three-way valve 76 is connected to one end of the pipe 64c, the other end of which is connected to the waste unit 72.

[0097] The waste section 72 is, for example, a drainage facility provided in a factory, a research facility, or the like, but may also be the above-mentioned collection box 60. The fluid 21 delivered to the waste section 72 through the pipe section 64c is discarded in the waste section 72.

[0098] A pipe 64d is attached to the bottom of the purified water tank 64, and the pipe 64d is connected to a second supply unit 80. The second supply unit 80 supplies purified water 19 from the purified water tank 64 via the pipe 64d to the treated water tank 32, the pure water generating device 82a, or the drainage facility 82b.

[0099] The second supply unit 80 has a second pump 84 such as a turbo pump or a positive displacement pump. The second supply unit 80 further has a three-way valve 86 that switches the destination of the purified water 19 between the treated water tank 32 or the pure water generator 82a.

[0100] The three-way valve 86 of this embodiment is also an electrically operated valve controlled by a controller 90, which will be described later. One end of a pipe section 64e is connected to the three-way valve 86, and the other end of the pipe section 64e is connected to the top (or side) of the treated water tank 32.

[0101] When the purified water tank 64 and the treated water tank 32 are connected via pipe section 64d and pipe section 64e (i.e., a second path different from the first path), the purified water 19 in the purified water tank 64 is supplied to the treated water tank 32.

[0102] On the other hand, when the purified water tank 64 is connected to the three-way valve 82c via the pipes 64d and 64f, the purified water 19 in the purified water tank 64 is further purified by the pure water generator 82a and reused as the grinding water 15 for the grinding device 2, or is discarded to the drainage facility 82b. The drainage facility 82b may also be used as the disposal unit 72.

[0103] The pure water generating device 82a includes a filtration filter that filters out and separates relatively large impurities, an ion exchange resin that removes impurity ions from the purified water 19, and an ultraviolet irradiation device that irradiates ultraviolet rays to decompose organic matter contained in the purified water 19.

[0104] Fig. 2 is a block diagram of the above-mentioned machining debris removal device 30. As shown in Fig. 2, the operations of the carbon dioxide supply unit 36, the pump 40a, the removal unit 44, the moving mechanism 50, the drying mechanism 54, the first feeding unit 70, the second feeding unit 80, etc. are controlled by a controller 90.

[0105] 2, the relationship between the tank and the measuring unit and the piping are indicated by solid lines, and the electrical connection between the controller 90 and the components is indicated by dashed arrows. The untreated water pH measuring unit 38, the purified water pH measuring unit 66, and the gas amount measuring unit 68 transmit information obtained by measurement (i.e., pH and gas amount) to the controller 90.

[0106] The controller 90 is configured by a computer including, for example, a processor represented by a CPU (Central Processing Unit) and a memory. The memory includes a main storage device such as a DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a flash memory, a hard disk drive, or a solid state drive.

[0107] The auxiliary storage device stores software including a predetermined program. The functions of the controller 90 are realized by operating the processor and the like in accordance with this software.

[0108] The predetermined program may be stored in a non-transitory tangible recording medium such as a USB (Universal Serial Bus) memory, an optical disk, an SD memory card, or an HDD (hard disk drive) instead of an auxiliary storage device.

[0109] The controller 90 decides whether or not to supply the fluid 21 in the purified water tank 64 to the treated water tank 32 via the first supply unit 70 based on the pH of the water to be treated 17 in the treated water tank 32 measured by the treated water pH measuring unit 38.

[0110] More specifically, the controller 90 controls the three-way valve 76 of the first supply section 70 based on the pH of the water to be treated 17 in the water to be treated tank 32 measured by the water to be treated pH measuring section 38, thereby switching whether the fluid 21 in the purified water tank 64 is to be supplied to the water to be treated tank 32 or the waste section 72.

[0111] When the aim is to adjust the pH of the water to be treated 17 in the water to be treated tank 32 to 4.0 (i.e., when the target pH is 4.0), the controller 90 causes the first supply unit 70 to supply the fluid 21 in the purified water tank 64 to the water to be treated tank 32 when the pH of the water to be treated 17 in the water to be treated tank 32 is 4.0 or higher.

[0112] Therefore, the carbon dioxide 36b supplied from the carbon dioxide supply unit 36 ​​to the water to be treated 17 can be effectively utilized, and the amount of carbon dioxide 36b used in the carbon dioxide supply unit 36 ​​can be reduced compared to when no fluid 21 is supplied to the water to be treated tank 32.

[0113] On the other hand, when the target pH is 4.0 and the pH of the water to be treated 17 in the water to be treated tank 32 is less than 4.0, the controller 90 causes the first feeding unit 70 to feed the fluid 21 to the waste unit 72.

[0114] If the pH of the water to be treated 17 in the water to be treated tank 32 is strongly acidic, for example, less than 3.0, the processing debris 13 contained in the water to be treated 17 will aggregate and tend to settle in the water to be treated tank 32, making it difficult to remove the processing debris 13 by electrophoresis in the process tank 42.

[0115] Therefore, in this case, the controller 90 causes the first feeding unit 70 to feed the fluid 21 to the waste unit 72. This makes it possible to prevent the processing debris 13 from flocculating and settling in the tank 32 for treated water.

[0116] Furthermore, the controller 90 determines whether or not to feed the fluid 21 in the purified water tank 64 to the treated water tank 32 by the first feeding unit 70 based on the amount of gas measured by the gas amount measuring unit 68.

[0117] For example, when the controller 90 determines that the pH of the water to be treated 17 in the water to be treated tank 32 needs to be made lower than the current pH (i.e., more acidic), and the amount of gas in the purified water tank 64 exceeds 1.0 L, the controller 90 causes the first supply unit 70 to supply the fluid 21 to the water to be treated tank 32.

[0118] Incidentally, the controller 90 may cause the second supply unit 80 to supply the purified water 19 to the treated water tank 32 when the pH of the purified water 19 in the purified water tank 64 measured by the purified water pH measuring unit 66 satisfies a predetermined condition.

[0119] More specifically, if the pH of the purified water 19 is 4.0 or higher, or if the pH of the purified water 19 is higher than the pH of the water to be treated 17, the controller 90 may cause the second supply unit 80 to supply the purified water 19 to the water to be treated tank 32.

[0120] This prevents the processing debris 13 from coagulating and settling within the treated water tank 32, and by circulating the purified water 19 to the process tank 42, the processing debris 13 contained in the purified water 19 can be further removed in the removal section 44.

[0121] Such circulation of the purified water 19 is performed, for example, when the pH of the purified water 19 satisfies a predetermined condition and the purified water 19 in the purified water tank 64 is not supplied to either the pure water generating device 82a or the drainage equipment 82b.

[0122] Next, a pH adjustment method for adjusting the pH of the tank 32 for treated water in the processing debris removal device 30 will be described with reference to Fig. 3. Fig. 3 is a flow chart of the pH adjustment method in the processing debris removal device 30.

[0123] In this embodiment, the pH adjustment method is carried out by having the processor execute the above-mentioned predetermined program and having the controller 90 control the operation of the chip removal device 30.

[0124] In the pH adjustment method of this embodiment, when treating the water to be treated 17 as described above, the following steps are sequentially performed: a first pH adjustment step S10, a purified water production step S20, a water storage step S30, a judgment step S40, and a fluid supply step S52 or a fluid disposal step S54 (i.e., a second pH adjustment step S50).

[0125] The used grinding water 15 flows into the tank 32 from the water case 22 at a predetermined flow rate per unit time, and the pH measuring unit 38 measures the pH of the water 17 in the tank 32 to be treated, thereby monitoring the pH of the water 17 (pH measuring step). The pH measuring step is carried out continuously or intermittently once the water 17 enters the tank 32.

[0126] The controller 90 changes the valve 34a from a closed state to an open state, thereby supplying carbon dioxide 36b from the carbon dioxide supply unit 36 ​​to the water to be treated 17 supplied from the drain outlet 24 of the water case 22 and stored in the water to be treated tank 32. This adjusts the pH of the water to be treated 17 in the water to be treated tank 32 to, for example, weak acidity (first pH adjustment step S10).

[0127] The controller 90 operates the pump 40a to send the treated water 17, whose pH has been adjusted in this manner, from the treated water tank 32 to the process tank 42, and then the processing debris 13 contained in the treated water 17 is removed using electrophoresis in the removal section 44 provided in the process tank 42 (purified water production process S20).

[0128] In the purified water generating step S20, the duration and voltage of current application to the holding plate 46 and the second side portion 48c are controlled by the controller 90. By holding the processing debris 13 on the holding plate 46, the water to be treated 17 becomes purified water 19 from which the processing debris 13 has been removed. As described above, not all of the processing debris 13 has been removed in the purified water 19.

[0129] The purified water 19 is taken out from the outlet 48d of the housing 48, delivered to the purified water tank 64 via the pipe section 62, and stored in the purified water tank 64 (water storage step S30). The controller 90 operates the first pump 74 or the second pump 84 to deliver the purified water to the purified water tank 64.

[0130] The controller 90 determines whether the fluid 21 containing the carbon dioxide 36b in the purified water tank 64 should be fed to the tank 32 for treated water or discarded, based on the pH of the water 17 to be treated in the tank 32 for treated water.

[0131] If the pH of the water to be treated 17 is higher than a predetermined value (e.g., 4.0) (e.g., 4.1) in the pH measurement process (i.e., YES in S40), the controller 90 appropriately operates the first supply unit 70 to supply fluid 21 from the purified water tank 64 to the water to be treated 17 stored in the water to be treated tank 32 to lower the pH (i.e., adjust to a lower value) (fluid supply process S52 of the second pH adjustment process S50).

[0132] This allows for effective use of the carbon dioxide 36b supplied to the water to be treated 17, thereby reducing the amount of carbon dioxide 36b used in the carbon dioxide supply unit 36 ​​compared to when the fluid 21 is not supplied to the water to be treated tank 32. Furthermore, because the pH of the water to be treated 17 is relatively high, at or above a predetermined value, even when the fluid 21 is supplied, it is possible to prevent the processing debris 13 from flocculating and settling in the water to be treated tank 32.

[0133] On the other hand, if the pH of the water to be treated 17 is less than a predetermined value (e.g., 4.0) (e.g., 3.9) during the pH measurement process (i.e., NO in S40), the controller 90 appropriately operates the first supply unit 70 to discard the fluid 21 to the disposal unit 72 without supplying it to the water to be treated 17 stored in the water to be treated tank 32 (fluid disposal process S54 of the second pH adjustment process S50).

[0134] When the pH of the water to be treated 17 is relatively low, the fluid 21 is discarded without being circulated to the water to be treated tank 32, thereby preventing the processing waste 13 from flocculating and settling in the water to be treated tank 32.

[0135] Although not shown in the flow diagram of Figure 3, if the amount of gas in the purified water tank 64 becomes excessive, the fluid 21 may be discarded, or the fluid 21 may be supplied from the purified water tank 64 to the pipe section 34 via a pipe section not shown, thereby utilizing the fluid 21 as a new source of carbon dioxide 36b.

[0136] The controller 90 may further, based on the amount of gas in the purified water tank 64 measured by the gas amount measuring unit 68 (for example, when it determines that the pH of the water to be treated 17 in the water to be treated tank 32 needs to be made lower than the current pH (i.e., closer to acidic) and the amount of gas in the purified water tank 64 exceeds 1.0 L), cause the first supply unit 70 to supply the fluid 21 to the water to be treated tank 32 (excess fluid supply process).

[0137] In addition, the controller 90 may cause the second supply section 80 to supply the purified water 19 to the treated water tank 32 (purified water circulation process) when the pH of the purified water 19 meets a predetermined condition (for example, when the pH of the purified water 19 is 4.0 or higher, or when the pH of the purified water 19 is higher than the pH of the water to be treated 17).

[0138] In addition, the structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. An electrically driven valve having three ports (for example, a three-port solenoid valve) may be used instead of the three-way valves 76, 86, and 82c. [Explanation of symbols]

[0139] 2: grinding device, 4: base, 4a: opening 6: chuck table, 6a: holding surface, 6b: rotation axis 8: Rotation drive source 10: Grinding unit, 12: Spindle housing, 14: Spindle 11: Workpiece, 13: Processing waste, 15: Grinding water 16: Mount, 18: Grinding wheel 17: Water to be treated, 19: Purified water, 21: Fluid 20: Cover, 22: Water case, 24: Drain outlet, 26: Pipe section 30: Processing waste removal device 32: Treated water tank 34: Pipe portion, 34a: Valve 36: carbon dioxide supply unit, 36a: container, 36b: carbon dioxide 38: pH measurement unit for treated water, 38a: probe, 38b: pH measurement main body 40: Pipe section, 40a: Pump 42: Process tank, 42a: Top surface 44: Removal part, 46: Holding plate, 46a: Projection part 48: Housing, 48a: Top portion, 48b: Bottom portion, 48c: Second side portion, 48d: Outlet 50: moving mechanism, 50a: locking portion 50b: Height direction movement mechanism, 50c: Horizontal direction movement mechanism 52: Scraping mechanism, 52a: Box body, 52b: Slit, 52c: Plate part 54: Drying mechanism, 56: Housing, 56a: Carrying entrance, 56b: Carrying exit, 58: Belt conveyor 60: Collection box 62: Pipe section, 62a: Discharge port 64: Purified water tank, 64a, 64b, 64c, 64d, 64e: Pipe section, 64z: Height direction 66: Purified water pH measurement unit, 66a: Probe, 66b: pH measurement unit 68: Gas volume measurement unit 70: First feeding section, 74: First pump, 76: Three-way valve (switching section) 72: Disposal Department 80: second feeding section, 84: second pump, 86: three-way valve (switching section) 82a: pure water generator, 82b: drainage equipment, 82c: three-way valve 90: Controller S10: First pH adjustment process, S20: Purified water production process, S30: Water storage process S40: Judgment process S50: second pH adjustment step, S52: fluid supply step, S54: fluid disposal step

Claims

1. A processing debris removal device for removing processing debris contained in water to be treated, a water tank for storing the water to be treated; a carbon dioxide supply unit that supplies carbon dioxide to the water to be treated stored in the water to be treated tank; a process tank for storing the water to be treated delivered from the water to be treated tank; a removal unit having at least one pair of electrodes provided in the process tank, which removes the processing debris contained in the water to be treated stored in the process tank by retaining the processing debris on one of the at least one pair of electrodes using electrophoresis, thereby producing purified water; an airtight purified water tank for storing the purified water delivered from the process tank; a first supply unit that supplies the fluid containing carbon dioxide that was dissolved or mixed in the purified water but has been separated as a gas from the purified water in the purified water tank to the water-to-be-treated tank; a water-to-be-treated pH measuring unit for measuring the pH of the water to be treated stored in the water-to-be-treated tank; a controller; The processing debris removal device is characterized in that the controller decides whether or not to supply the fluid in the purified water tank to the treated water tank using the first supply unit based on the pH of the treated water in the treated water tank measured by the treated water pH measuring unit.

2. Further provided is a disposal unit for disposing of the fluid in the purified water tank, The first supply unit has a switching unit that switches the destination of the fluid to the treated water tank or the waste unit, The processing debris removal device described in claim 1, characterized in that the controller switches whether the fluid in the purified water tank is supplied to the treated water tank or the waste section by controlling the switching section based on the pH of the treated water in the treated water tank measured by the treated water pH measuring section.

3. Further provided is a gas amount measuring unit that measures the amount of gas in the purified water tank, The processing debris removal device described in claim 1 or 2, characterized in that the controller determines whether or not to supply the fluid in the purified water tank to the treated water tank by the first supply unit based further on the gas amount measured by the gas amount measuring unit.

4. a second supply unit that supplies the purified water in the purified water tank to the treated water tank through a second path different from a first path through which the first supply unit supplies the fluid from the purified water tank to the treated water tank; a purified water pH measuring unit for measuring the pH of the purified water stored in the purified water tank, 3. The processing debris removal device according to claim 1, wherein the controller controls the second supply unit to supply the purified water to the untreated water tank when the pH of the purified water satisfies a predetermined condition.

5. 1. A pH adjustment method for adjusting the pH of a water tank in which water to be treated is stored in a wastewater removal device that removes wastewater contained in the water to be treated, comprising: a first pH adjustment step of supplying carbon dioxide to the water to be treated stored in the water to be treated tank to adjust the pH of the water to be treated; a purified water producing step of producing purified water by removing the processing debris contained in the treated water whose pH has been adjusted by the first pH adjusting step using electrophoresis; a water storage step of supplying the purified water to an airtight purified water tank and storing the purified water; a pH measurement step of measuring the pH of the water to be treated in the water to be treated tank; a second pH adjustment step in which, if the pH of the water to be treated is equal to or higher than a predetermined value in the pH measurement step, a fluid containing carbon dioxide that was dissolved or mixed in the purified water stored in the purified water tank but has been separated as a gas from the purified water is supplied to the water to be treated stored in the water to be treated tank to adjust the pH, but if the pH of the water to be treated is lower than the predetermined value in the pH measurement step, the fluid is not supplied to the water to be treated stored in the water to be treated tank; A pH adjusting method comprising:

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