Vacuum generation device

Abstract

To use drain water of a water-sealing type vacuum pump as sealing water without newly installing a heat exchanger in a circulation path.SOLUTION: A vacuum generator comprises: a water-sealing type vacuum pump having a suction port, a discharge port and a water supply port; a suction pipe part for making an object to which a vacuum generated by the water-sealing type vacuum pump is transmitted and the suction port communicate with each other; a drain tank communicating with the discharge port, and storing drain water discharged from the discharge port; a circulation pipe part communicating with the drain tank and the water supply port, and making the drain water which is stored in the drain tank circulate to the water-sealing type vacuum pump as sealing water; and a water supply pipe part communicating with a cold water supply source and the water supply port, and supplying cold water as the sealing water to the water-sealing type vacuum pump. A part of the suction pipe part is arranged in the drain tank, and when using the water-sealing type vacuum pump, the drain water which is heated by the water-sealing type vacuum pump, and stored in the drain tank is cooled by the suction pipe part which is cooled by vacuum evaporation cooling.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vacuum generating device for generating a vacuum.

Background Art

[0002] Workpieces such as semiconductor wafers are ground using a grinding device and cut using a cutting device. Processing devices such as grinding devices and cutting devices usually include a holding table for sucking and holding a workpiece under negative pressure. The holding table is connected to a vacuum generating device, and the negative pressure generated by the vacuum generating device is transmitted to the holding table.

[0003] As such a vacuum pump (i.e., a vacuum pump) used in a vacuum generating device, a water-sealed vacuum pump that generates a negative pressure using an impeller disposed in a casing and sealing water supplied to the casing is generally used.

[0004] In a water-sealed vacuum pump, for example, cold water at about 20°C is used as the sealing water. With the use of the water-sealed vacuum pump, the sealing water is discharged from the casing as drainage, so new sealing water is supplied to the casing to supplement the discharged sealing water.

[0005] The drainage from the casing and the sealing water supplied to the casing are, for example, about 5 L / min each. Therefore, when all the drainage from the casing is discarded, a relatively large amount of water is consumed. Thus, it is conceivable to reuse the drainage from the casing by circulating it back to the sealing water.

[0006] However, due to the heat generation of a motor or the like associated with the use of the water-sealed vacuum pump, the sealing water in the casing rises by about 2°C to 3°C per minute. In addition, in a water-sealed vacuum pump, a limit temperature (for example, 50°C) for normal operation is predetermined.

[0007] Therefore, simply circulating the wastewater from the casing back into the seal water would cause the water-sealed vacuum pump to quickly reach the aforementioned limit temperature, making long-term operation difficult. Thus, it has been proposed to install a heat exchanger in the circulation path that circulates the wastewater as seal water, cooling the wastewater before reusing it as seal water (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2002-144181 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, installing a new heat exchanger increases the manufacturing cost of the vacuum generating device. This invention has been made in view of these problems, and aims to utilize the drainage from a water-sealed vacuum pump as sealing water without installing a new heat exchanger in the circulation path. [Means for solving the problem]

[0010] According to one aspect of the present invention, a vacuum generating apparatus is provided, comprising: a water-sealed vacuum pump having a suction port, a discharge port, and a water inlet; a suction pipe section connecting the suction port to an object to which the vacuum generated by the water-sealed vacuum pump is transmitted; a drainage tank communicating with the discharge port for storing drainage discharged from the discharge port; a circulation pipe section communicating with the drainage tank and the water inlet for circulating the drainage stored in the drainage tank to the water-sealed vacuum pump as sealing water; and a water supply pipe section communicating with a cold water supply source and the water inlet for supplying cold water as sealing water to the water-sealed vacuum pump, wherein a part of the suction pipe section is located inside the drainage tank, and when the water-sealed vacuum pump is in use, the drainage heated by the water-sealed vacuum pump and stored in the drainage tank is cooled by the suction pipe section cooled by vacuum vaporization cooling.

[0011] Preferably, the suction pipe section includes a check valve having a main body made of a material with a higher thermal conductivity than the material of the pipe constituting the suction pipe section, and the check valve is located inside the drain tank.

[0012] Preferably, the system further includes a chilled water flow rate adjustment unit that includes an on / off valve provided in the water supply pipe section and adjusts the flow rate of the chilled water, a drainage temperature detection unit that includes a temperature sensor provided in the circulation pipe section and detects the temperature of the drainage in the circulation pipe section, and a controller that controls the chilled water flow rate adjustment unit, wherein the controller increases the flow rate of the chilled water by the chilled water flow rate adjustment unit when the temperature of the drainage detected by the drainage temperature detection unit reaches a predetermined temperature or higher. [Effects of the Invention]

[0013] In a vacuum generating apparatus according to one aspect of the present invention, a portion of the suction pipe is located inside a drainage tank. When using a water-sealed vacuum pump, the drainage heated by the water-sealed vacuum pump and stored in the drainage tank is cooled by the suction pipe, which is cooled by vacuum vaporization cooling. Therefore, the drainage is cooled without installing a new heat exchanger in the circulation pipe between the drainage tank and the water-sealed vacuum pump, and the drainage from the water-sealed vacuum pump can be used as sealing water. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram showing a vacuum generation device. [Figure 2] This is a block diagram of a vacuum generation apparatus in a comparative example. [Figure 3] This is a perspective view of a polishing apparatus incorporating a vacuum generator. [Modes for carrying out the invention]

[0015] Referring to the accompanying drawings, an embodiment according to an aspect of the present invention will be described. FIG. 1 is a schematic diagram showing a vacuum generating device 2 according to the embodiment. In FIG. 1, a part of the components of the vacuum generating device 2 is shown by functional blocks, symbols, etc.

[0016] The vacuum generating device 2 has a water-sealed vacuum pump 4 that generates a vacuum. The water-sealed vacuum pump 4 includes a casing 4a having a cylindrical inner wall. Inside the casing 4a, an impeller (i.e., a rotor) that can rotate in an eccentric manner from the central axis of the cylinder is provided.

[0017] When the water-sealed vacuum pump 4 is in use, sealing water 6a is supplied into the casing 4a. As the impeller rotates, the sealing water 6a in the casing 4a moves along the cylindrical inner wall, forming a so-called liquid ring.

[0018] In a state where the liquid ring is formed, as the eccentric impeller rotates, the volume of the space surrounded by the impeller and the liquid ring changes. Along with this volume change, air containing liquid (e.g., water) is sucked in from the suction port 4b provided in the casing 4a.

[0019] Furthermore, the sucked air is compressed by the rotation of the impeller, and this compressed air is exhausted from the discharge port 4c provided in the casing 4a. Through such a series of operations, the water-sealed vacuum pump 4 generates a vacuum with a pressure lower than the atmospheric pressure.

[0020] When discharging air from the discharge port 4c, a part of the sealing water 6a used is discharged as drainage 6c. For example, 5 L / min of sealing water 6a is discharged. Therefore, when the water-sealed vacuum pump 4 is in use, the sealing water 6a is supplied to the water inlet 4d of the casing 4a through the water supply pipe portion 10.

[0021] The water supply pipe portion 10 includes a pipe communicating with the cold water supply source 8 and the water inlet 4d, and supplies cold water 6b as the sealing water 6a to the water-sealed vacuum pump 4. The cold water supply source 8 is not a part of the components of the vacuum generating device 2 but is externally attached to the vacuum generating device 2.

[0022] The cold water supply source 8 has a tank (not shown) in which water is stored. The water in the tank is maintained at a predetermined temperature of about 20°C by a cooling device or the like. From the tank, cold water 6b with a flow rate of, for example, 5 L / min is supplied to the water supply pipe portion 10 by a pump (not shown).

[0023] As the cold water 6b, it is preferable to use water (such as distilled water, tap water, etc.) containing impurities at an appropriate concentration. For example, if ultrapure water or pure water with relatively few impurities (for example, the specific resistance value at 25°C exceeds 10 MΩ·cm) is used as the cold water 6b, the pipe portion constituting the vacuum generating device 2 is relatively likely to corrode.

[0024] Also, for example, if tap water with relatively many impurities (for example, the specific resistance value at 25°C is about 0.01 MΩ·cm) is used as the cold water 6b, bacteria are relatively likely to multiply in the pipe portion constituting the vacuum generating device 2.

[0025] Therefore, as the cold water 6b, it is preferable to use water having a specific resistance value between ultrapure water and tap water (for example, water having a specific resistance value at 25°C of 0.5 MΩ·cm or more and 5 MΩ·cm or less, and as an example, distilled water).

[0026] A first solenoid valve 12 is provided in the water supply pipe portion 10. The first solenoid valve 12 is, for example, normally closed and its opening and closing are controlled by a controller 50 described later. Downstream of the first solenoid valve 12 in the flow direction of the cold water 6b, the water supply pipe portion 10 branches into a first water supply pipe portion 10a and a second water supply pipe portion 10b.

[0027] The first water supply pipe portion 10a also has a pipe, and a first throttle valve 14 is provided in this pipe. The first throttle valve 14 controls the flow rate of the cold water 6b flowing through the first water supply pipe portion 10a to a first predetermined value (for example, 1 L / min).

[0028] The second water supply pipe portion 10b also has a pipe, and a second solenoid valve (on-off valve) 16 is provided in this pipe. The second solenoid valve 16 is, for example, normally closed and its opening and closing are controlled by a controller 50 described later.

[0029] In the second water supply pipe section 10b, a second throttle valve 18 is provided downstream of the second solenoid valve 16. The second throttle valve 18 controls the flow rate of the cold water 6b flowing through the second water supply pipe section 10b to a second predetermined value (for example, 2 L / min) that is higher than a first predetermined value.

[0030] In the flow direction of the chilled water 6b, the first water supply pipe section 10a and the second water supply pipe section 10b are connected at a first position 10c downstream of the first throttle valve 14 and the second throttle valve 18. Therefore, the flow rate of the chilled water 6b flowing through the water supply pipe section 10 is the sum of the flow rate of the first water supply pipe section 10a and the flow rate of the second water supply pipe section 10b.

[0031] For example, when the first solenoid valve 12 is open and the second solenoid valve 16 is closed, chilled water 6b at a first predetermined flow rate (e.g., 1 L / min) is supplied from the first position 10c. In contrast, when both the first solenoid valve 12 and the second solenoid valve 16 are open, chilled water 6b at a flow rate equal to the sum of the first predetermined value and the second predetermined value (e.g., 3 L / min) is supplied from the first position 10c.

[0032] In this manner, the first water supply pipe section 10a, the first throttle valve 14, the second water supply pipe section 10b, the second solenoid valve 16, the second throttle valve 18, etc., each provided in the water supply pipe section 10, function as a chilled water flow rate adjustment unit 20 that adjusts the flow rate of chilled water 6b supplied to the water-sealed vacuum pump 4.

[0033] The chilled water flow rate adjustment unit 20 supplies chilled water 6b, which functions as a seal water 6a, to the water inlet 4d via the third solenoid valve 22 at a predetermined flow rate. The third solenoid valve 22 is, for example, normally closed and its opening and closing is controlled by the controller 50, which will be described later.

[0034] A drain pipe section 24 is connected to the outlet 4c of the water-sealed vacuum pump 4. The drain pipe section 24 includes a pipe that connects the outlet 4c of the water-sealed vacuum pump 4 to the first opening 26a of the drain tank 26.

[0035] The sealing water 6a used in the water-sealed vacuum pump 4 is discharged as wastewater 6c from the outlet 4c through the drain pipe section 24 to the drain tank 26. The first opening 26a is formed near the upper end of the drain tank 26.

[0036] The drainage tank 26 can store, for example, about 10 to 20 liters of drainage 6c. A second opening 26b is formed near the upper end of the drainage tank 26. An overflow pipe 28 is connected to the second opening 26b to prevent water from overflowing from the drainage tank 26 when the water level exceeds a predetermined threshold.

[0037] A third opening 26c is formed near the lower end of the drainage tank 26. A drain pipe 30 is connected to the third opening 26c for forcibly discharging the wastewater 6c from the drainage tank 26. A fourth solenoid valve 32 is provided in the drain pipe 30.

[0038] The fourth solenoid valve 32 is, for example, normally closed and its opening and closing is controlled by a controller 50, which will be described later. When the fourth solenoid valve 32 is opened, the wastewater 6c in the wastewater tank 26 is discharged to the outside of the vacuum generating device 2 via the wastewater pipe 30.

[0039] In the flow direction of the wastewater 6c in the drain pipe 30, the overflow pipe 28 is connected to a predetermined position 30a downstream of the fourth solenoid valve 32, and the wastewater 6c flowing into the overflow pipe 28 is also discharged through the drain pipe 30.

[0040] Near the lower end of the drain tank 26, a fourth opening 26d is formed at a different location from the third opening 26c. One end of a pipe constituting the circulation pipe section 34 is connected to the fourth opening 26d. In other words, the circulation pipe section 34 is in communication with the drain tank 26.

[0041] The other end of the circulation pipe section 34 is connected to the water supply pipe section 10 at a second position 10d, which is located between the first position 10c and the third solenoid valve 22 described above. In other words, the circulation pipe section 34 is in communication with the water inlet 4d of the water-sealed vacuum pump 4 via the third solenoid valve 22.

[0042] A temperature sensor 36a is provided near the fourth opening 26d in the circulation pipe section 34. The wastewater temperature detection unit 36, which includes the temperature sensor 36a, detects the temperature of the wastewater 6c in the circulation pipe section 34.

[0043] By placing the temperature sensor 36a outside the drainage tank 26, the temperature of the drainage 6c can be detected after it has been heated by the water-sealed vacuum pump 4 and then cooled inside the drainage tank 26, as described later.

[0044] Downstream from the wastewater temperature detection unit 36, a pump 38 for supplying wastewater 6c is provided. Further downstream from the pump 38, a check valve 40 is provided. The main body (e.g., housing) of the check valve 40 is made of brass.

[0045] By operating the pump 38, the wastewater 6c in the wastewater tank 26 is supplied as sealing water 6a to the second position 10d of the water supply pipe section 10. In this way, the wastewater 6c in the wastewater tank 26 is circulated as sealing water 6a to the water-sealed vacuum pump 4.

[0046] However, when using the water-sealed vacuum pump 4, the water-sealed vacuum pump 4 heats the wastewater 6c, and the temperature of the wastewater 6c rises above the temperature of the cold water 6b. Moreover, the water-sealed vacuum pump 4 has a predetermined limit temperature at which it operates normally.

[0047] Therefore, in this embodiment, the wastewater 6c is cooled inside the wastewater tank 26. To this end, a portion of the suction pipe section 44, which connects the chuck table (i.e., the object) 42 to which the vacuum generated by the water-sealed vacuum pump 4 is transmitted, and the suction port 4b, is placed inside the wastewater tank 26.

[0048] The suction tube section 44 is mostly composed of a tube 46a made of a resin with relatively low thermal conductivity. For example, the resin used for the tube 46a is a urethane resin with a thermal conductivity of approximately 0.3 W / mK.

[0049] In contrast, a portion of the suction pipe section 44 located inside the drainage tank 26 has a check valve 46b. The check valve 46b has a main body (e.g., housing) made of a metal such as carbon steel, stainless steel, pig iron, or copper alloy. Such metal materials have a higher thermal conductivity than the resin material that constitutes the pipe 46a.

[0050] The main body of the check valve 46b is made of stainless steel, for example, having a thermal conductivity of approximately 16.7 W / mK. The check valve 46b is positioned inside the drain tank 26, for example, resting on the bottom of the drain tank 26, but it may also be positioned a predetermined distance above the bottom of the drain tank 26, as long as it is below the water level of the drain 6c.

[0051] A fluid 44a containing ambient gas (e.g., air), water, and processing debris is drawn in from the chuck table 42. Since the fluid 44a contains water, it is cooled by vacuum vaporization cooling when it is drawn into the suction port 4b. As a result, the temperature inside the suction tube 44 is lower than that of the external environment.

[0052] In this embodiment, a metal check valve 46b is placed at a predetermined position in the drain tank 26 located below the second opening 26b, thereby cooling the wastewater 6c stored in the drain tank 26 by the check valve 46b, which is cooled by the vacuum vaporization cooling of the fluid 44a.

[0053] Furthermore, the cooled check valve 46b cools the wastewater 6c in such a way that it offsets approximately 5% to 10% of the heat generated by the water-sealed vacuum pump 4. In other words, the wastewater 6c is cooled to a temperature higher than that of the chilled water 6b, but lower than that of the wastewater 6c immediately after use.

[0054] Therefore, without installing a new heat exchanger in the circulation pipe section 34 between the drain tank 26 and the water-sealed vacuum pump 4, the drained water 6c can be cooled, and the drained water 6c from the water-sealed vacuum pump 4 can be used as the sealing water 6a. Furthermore, this method is more cost-effective than installing a new heat exchanger.

[0055] In addition, by making most of the suction pipe section 44 out of a resin pipe 46a with relatively low thermal conductivity, it is possible to suppress the heating of the vacuum vapor-cooled fluid 44a from the external environment. Therefore, compared to the case where most of the suction pipe section 44 is made out of a metal pipe instead of a resin pipe 46a, the cooling effect of the wastewater 6c at the check valve 46b can be improved.

[0056] Alternatively, instead of the check valve 46b, a portion of the suction pipe section 44 may be made of a metal pipe, and this metal pipe may be placed inside the drainage tank 26. In addition, a portion of the suction pipe section 44 may be made of a metal pipe, and both the metal pipe and the check valve 46b may be placed inside the drainage tank 26.

[0057] The operation of the water-sealed vacuum pump 4, the chilled water flow rate adjustment unit 20, the third solenoid valve 22, the fourth solenoid valve 32, the pump 38, etc., is controlled by the controller 50. The controller 50 is composed of a computer including, for example, a processor (processing unit) represented by a CPU (Central Processing Unit) and memory (storage device).

[0058] The memory includes a main memory such as DRAM (Dynamic Random Access Memory) and an auxiliary memory such as flash memory, a hard disk drive, or a solid-state drive. Software containing a predetermined program is stored in the auxiliary memory. The functions of the controller 50 are realized by operating the processing unit and other components according to this software.

[0059] The controller 50 is not limited to the computer described above; an MCU (Micro Controller Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), etc., may also be used.

[0060] The controller 50 adjusts the ratio of cold water 6b to wastewater 6c that constitutes the seal water 6a according to the temperature of the wastewater 6c in the circulation pipe section 34.

[0061] For example, if the temperature of the wastewater 6c in the circulation pipe section 34 is below 35°C, the controller 50 closes the second solenoid valve 16 to set the flow rate of the chilled water 6b to 1 L / min, and the flow rate of the wastewater 6c supplied from the pump 38 to 4 L / min. This supplies a total of 5 L / min of sealing water 6a to the water-sealed vacuum pump 4.

[0062] In response, the controller 50 increases the flow rate of the chilled water 6b when the temperature of the wastewater 6c detected by the wastewater temperature detection unit 36 ​​reaches a predetermined temperature (for example, 45°C) or higher.

[0063] For example, the controller 50 opens the second solenoid valve 16 (i.e., the chilled water flow rate adjustment unit 20) to set the flow rate of chilled water 6b supplied from the water supply pipe 10 to 3 L / min and the flow rate of wastewater 6c supplied from the pump 38 to 2 L / min. This supplies a total of 5 L / min of sealing water 6a to the water-sealed vacuum pump 4.

[0064] In this way, when the temperature of the wastewater 6c in the circulation pipe section 34 is relatively low, water can be saved while maintaining proper operation of the water-sealed vacuum pump 4 by reducing the consumption of chilled water 6b from the chilled water supply source 8.

[0065] Figure 2 is a block diagram showing a vacuum generating apparatus 52 in a comparative example. In the vacuum generating apparatus 52, the pipe 46a of the circulation pipe section 34 does not pass through the drainage tank 26. Therefore, the check valve 46b of the circulation pipe section 34 is also located outside the drainage tank 26, and even if vacuum vaporization cooling of the fluid 44a occurs, the check valve 46b cannot cool the drainage 6c in the drainage tank 26.

[0066] Figure 3 is a perspective view of the polishing apparatus 62 incorporating the vacuum generator 2. In Figure 3, the X-axis, Y-axis, and Z-axis directions are orthogonal to each other. The polishing apparatus 62 has a base 64. Cassette mounting platforms 66a and 66b are provided on the upper surface of the front portion of the base 64.

[0067] A first cassette 68a containing one or more workpieces 11 is placed on the cassette mounting base 66a, and a second cassette 68b for containing one or more workpieces 11 is placed on the cassette mounting base 66b. Each workpiece 11 is protected on the side opposite to the surface to be polished by a resin protective tape 13.

[0068] An opening 64a is formed between the cassette mounting tables 66a and 66b, and a transport robot 70 having a multi-bar linkage mechanism for transporting the workpiece 11 is installed in the opening 64a. The transport robot 70 transports the workpiece 11 to a positioning table 72, which adjusts the position of the workpiece 11 using a plurality of positioning pins.

[0069] The workpiece 11 is positioned on the positioning table 72 and then transported to the chuck table 76 by the loading arm 74. The chuck table 76 is movable between the loading / unloading position A1 and the polishing position A2 by an X-axis movement mechanism (not shown).

[0070] The chuck table 76 corresponds to the chuck table 42 shown in Figure 1 and has the function of holding the workpiece 11 by suction. The chuck table 76 is rotatable around a rotation axis positioned substantially parallel to the Z-axis direction by a rotation drive source (not shown).

[0071] The chuck table 76 has a metal, disc-shaped frame. A disc-shaped recess is formed in the upper part of the frame. A porous plate made of porous ceramics is fixed in this recess. The upper surfaces of the frame and the porous plate are substantially flush, forming a holding surface 76a that is substantially parallel to the XY plane.

[0072] Grooves, through-holes, etc., that constitute the flow path are formed at the bottom of the recess of the frame. The through-hole that penetrates the bottom of the frame is connected to the suction pipe section 44 of the vacuum generation device 2 described above. Negative pressure is transmitted from the suction pipe section 44 to the upper surface of the porous plate.

[0073] A polishing unit 78 is provided above the chuck table 76, which is positioned at polishing position A2. The polishing unit 78 has a cylindrical spindle housing 80. A portion of a cylindrical spindle 82 is rotatably housed inside the spindle housing 80.

[0074] The lower end of the spindle 82 protrudes below the lower end of the spindle housing 80. A disc-shaped mount 84 is fixed to the lower end of the spindle 82. A disc-shaped polishing wheel 86, which has approximately the same diameter as the mount 84, is mounted on the underside of the mount 84. The polishing wheel 86 has a larger diameter than the chuck table 76.

[0075] The polishing unit 78 is movable in the Z-axis direction by a Z-axis direction movement mechanism 88. The Z-axis direction movement mechanism 88 has a pair of guide rails 90 arranged along the Z-axis direction. A movable plate 92 is fixed to the pair of guide rails 90 so as to be slidable along the Z-axis direction.

[0076] A nut portion (not shown) is provided on the back side of the movable plate 92. A screw shaft 94 is rotatably fixed to the nut portion via a ball (not shown). A drive source 96, such as a stepping motor, is fixed to the upper end of the screw shaft 94.

[0077] The polishing unit 78 described above is fixed to the surface side of the movable plate 92. When the screw shaft 94 is rotated by the drive source 96, the polishing unit 78 moves along the Z-axis direction. During polishing, first, one side of the workpiece 11 is held by suction using the chuck table 76 located at the loading / unloading position A1.

[0078] Next, the chuck table 76 is positioned at the polishing position A2. Then, the chuck table 76 and spindle 82 are rotated, and the polishing pad of the polishing wheel 86 is pressed against the other side of the workpiece 11. At this time, polishing fluid (not shown) is supplied from the polishing fluid supply source 98 through the flow path 82a formed in the spindle 82.

[0079] After polishing, the chuck table 76 is returned to the loading / unloading position A1, and the polished workpiece 11 is transported to the spinner cleaning unit 102 by the unloading arm 100. The workpiece 11, which has been cleaned in the spinner cleaning unit 102, is then transported by the transport robot 70 to the first cassette 68a or the second cassette 68b, which is the source of the transport.

[0080] Furthermore, the structures, methods, etc., according to the above embodiments can be modified as appropriate without departing from the scope of the present invention. The vacuum generating apparatus 2 is not limited to the chuck tables 42 and 76 described above, but can also be applied to chuck tables in which water may enter the suction tube section 44.

[0081] For example, the vacuum generator 2 can also be applied to the chuck tables of other processing equipment such as cutting machines, tool cutting machines, and grinding machines that use water during processing. In addition to the chuck table, the vacuum generator 2 may also supply negative pressure to other suction mechanisms such as suction pads.

[0082] Furthermore, the first solenoid valve 12, second solenoid valve 16, third solenoid valve 22, fourth solenoid valve 32, etc., used in the vacuum generation device 2 are not limited to solenoid valves and may be other types of on-off valves. For example, when controlled manually by an operator, globe valves, gate valves, ball valves, butterfly valves, diaphragm valves, etc., can be used. [Explanation of Symbols]

[0083] 2: Vacuum generator 4: Water-sealed vacuum pump 4a: Casing, 4b: Suction port, 4c: Discharge port, 4d: Water supply port 6a: Water seal, 6b: Cold water, 6c: Drainage 8:Cold water source 10: Water supply pipe section 10a: 1st water supply pipe section, 10b: 2nd water supply pipe section, 10c: 1st position, 10d: 2nd position 11: Workpiece, 13: Protective tape 12: First solenoid valve, 14: First throttle valve, 16: Second solenoid valve (on / off valve), 18: Second throttle valve 20: Chilled water flow rate adjustment unit 22: Third solenoid valve 24: Drain pipe section, 26: Drain tank 26a: first opening, 26b: second opening, 26c: third opening, 26d: fourth opening 28: Overflow pipe, 30: Drain pipe, 30a: Designated position, 32: Fourth solenoid valve 34: Circulation pipe section 36: Drainage temperature detection unit, 36a: Temperature sensor, 38: Pump, 40: Check valve 42: Chuck table (object) 44: Suction pipe section, 44a: Fluid, 46a: Tube, 46b: Check valve 50: Controller 52: Vacuum generator 62: Polishing device, 64: Base, 64a: Opening 66a, 66b: Cassette mounting tray, 68a: First cassette, 68b: Second cassette 70: Transport robot, 72: Positioning table, 74: Loading arm 76: Chuck table, 76a: Holding surface 78: Polishing unit, 80: Spindle housing 82: Spindle, 82a: Flow channel, 84: Mount, 86: Polishing wheel 88:Z-axis direction movement mechanism 90: Guide rail, 92: Moving plate, 94: Screw shaft, 96: Drive source 98: Polishing fluid supply source, 100: Unloading arm, 102: Spinner cleaning unit A1: Loading / unloading position, A2: Polishing position

Claims

1. A vacuum generating device that generates a vacuum, A water-sealed vacuum pump having a suction port, an outlet port, and a water inlet, A suction tube section that connects the object to which the vacuum generated by the water-sealed vacuum pump is transmitted to the suction port, A drainage tank is connected to the outlet and is used to store the wastewater discharged from the outlet. A circulation pipe section is connected to the drain tank and the water inlet, and is used to circulate the drain stored in the drain tank as sealing water to the water-sealed vacuum pump. A water supply pipe section is connected to the cold water supply source and the water inlet, and supplies cold water as sealing water to the water-sealed vacuum pump, Equipped with, A portion of the suction pipe is located inside the drainage tank. A vacuum generating apparatus characterized in that, when using the water-sealed vacuum pump, the wastewater heated by the water-sealed vacuum pump and stored in the wastewater tank is cooled by the suction pipe section, which is cooled by vacuum vaporization cooling.

2. The suction tube section includes a check valve having a main body made of a material with a higher thermal conductivity than the material of the tube constituting the suction tube section. The vacuum generating apparatus according to claim 1, characterized in that the check valve is located inside the drainage tank.

3. A cold water flow rate adjustment unit, which includes an on / off valve provided in the water supply pipe section, and adjusts the flow rate of the cold water, A wastewater temperature detection unit, which includes a temperature sensor provided in the circulation pipe section, detects the temperature of the wastewater in the circulation pipe section. The system further comprises a controller for controlling the chilled water flow rate adjustment unit, The vacuum generating apparatus according to claim 1 or 2, characterized in that the controller increases the flow rate of the chilled water by the chilled water flow rate adjustment unit when the temperature of the wastewater detected by the wastewater temperature detection unit reaches a predetermined temperature or higher.

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