Degassing device and degassing method for ultrasonic deburring system

Abstract

To provide an ultrasonic / vacuum-type degassing device and a degassing method thereof that can be incorporated into a deburring system that removes burrs from a workpiece with a cavity formed by ultrasonic waves and give stable degassing performance.SOLUTION: A degassing device includes: a cylindrical container which is positioned with its central axis in a vertical orientation; a degassing port which is located near an upper part of the cylindrical container to evacuate an internal closed space; a supply port which is positioned below the degassing port and on a sidewall of the cylindrical container to supply cleaning liquid into an internal closed space; a discharge port which is located at a bottom plate to discharge the cleaning liquid from the internal closed space; a window part which is provided by penetrating the sidewall of the cylindrical container below the supply port; a sealing wall which is provided to close the window part; and a vibrator which is attached to a rear surface of the sealing wall so as to reciprocate a front surface of the sealing wall toward the central axis. The degassing method uses the degassing device to introduce the cleaning liquid into the cylindrical container so as to heighten a water level position relative to the window part, and uses the vibrator to oscillate the sealing wall and radiate compressional waves to the cleaning liquid in the cylindrical container toward the central axis.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a degassing device and a degassing method for an ultrasonic deburring system in which a workpiece is placed in a degassed cleaning liquid and burrs are removed from the workpiece by a cavity formed by ultrasonic waves, and in particular to an ultrasonic / vacuum type degassing device and a degassing method. [Background technology]

[0002] There is known a deburring system in which a workpiece is immersed in a cleaning solution and ultrasonic waves are applied to the workpiece to remove burrs from the workpiece by forming cavities in the cleaning solution. In order to enhance the impact effect of cavitation caused by the formation and collapse of cavities, it is preferable to thoroughly remove gas in the cleaning solution that can become the core of cavities.

[0003] For example, Patent Document 1 discloses a deburring system in which a degassing means using hollow fibers is provided in the middle of a circulation path that circulates a cleaning liquid in a storage tank (deburring tank) equipped with an oscillator that irradiates ultrasonic waves while cooling the cleaning liquid. Although the degassing capacity depends on the hollow fibers, it is said that the system can degas the dissolved oxygen to 1 mg / l or less.

[0004] Patent Document 2 discloses a degassing device for a deburring system that applies ultrasonic waves to a degassing tank that is vacuumed after being supplied with a cleaning liquid. A vacuum pump is connected to the top side of the degassing tank that forms a closed space, and an ultrasonic vibrator with a vibration frequency of 25 KHz to 2 MHz is attached to the bottom side. When a cleaning liquid is supplied to the degassing tank and vibrations with a vibration frequency in the range of 35 to 45 KHz, particularly vibrations with a vibration frequency of 40 KHz, are applied, the amount of dissolved oxygen (DO value) is reduced to 2.5 mg / l or less within 10 minutes. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-180757 A [Patent Document 2] Patent No. 5999857 Summary of the Invention [Problem to be solved by the invention]

[0006] Although degassing means using hollow fibers have high degassing performance, the degassing ability of the hollow fibers changes due to dirt from the circulating cleaning liquid. In particular, in ultrasonic deburring systems, the cleaning liquid inevitably contains dirt and often contains surfactants and rust inhibitors, causing significant damage to the hollow fibers. On the other hand, ultrasonic / vacuum degassing devices that apply ultrasonic vibrations to cleaning water in a vacuum space to degas are less susceptible to the effects of dirt from the cleaning liquid, but they have problems such as a lack of degassing performance and operational stability.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide an ultrasonic / vacuum degassing device and degassing method that can be incorporated into a deburring system that includes a deburring device that places a workpiece in a degassed cleaning liquid and removes burrs from the workpiece by using a cavity formed by ultrasonic waves, and that can provide stable degassing performance. [Means for solving the problem]

[0008] The degassing device according to the present invention is an ultrasonic / vacuum type degassing device incorporated into an ultrasonic deburring system equipped with a deburring device that places a workpiece in a degassed cleaning liquid and removes burrs from the workpiece by a cavity formed by ultrasonic waves, and is characterized in that it has a cylindrical container arranged with its central axis vertical and having an internal closed space whose upper and lower parts are closed by a cover plate and a bottom plate, respectively, a degassing port provided near the upper part of the cylindrical container for evacuating the internal closed space, a supply port provided below the degassing port in the side wall of the cylindrical container for supplying the cleaning liquid to the internal closed space, and a discharge port provided in the bottom plate for discharging the cleaning liquid from the internal closed space, and further includes a window portion provided below the supply port that penetrates the side wall of the cylindrical container, a sealing wall provided to block the window portion, and a vibrator attached to the rear surface of the sealing wall so as to reciprocate the front surface of the sealing wall toward the central axis.

[0009] According to this feature, when the cleaning liquid is introduced into the cylindrical container so that the water surface position is at least higher than the window portion, a compressional wave can be emitted toward the central axis of the cylindrical container, and the air bubbles are immediately moved upward and destroyed without being allowed to float in the cleaning liquid, thereby obtaining stable degassing performance.

[0010] In the above-mentioned invention, the cylindrical container may be cylindrical, and an annular wall extending from the periphery of the window toward the outside of the side wall along a horizontal line extending vertically from the central axis may be provided, and the extending end of the annular wall may be closed to provide the sealing wall along a vertical plane having the horizontal line as a normal line. With such a feature, the flow of the cleaning liquid can be made smooth, and the area of ​​the sealing wall that introduces compressional waves can be made large, thereby obtaining stable degassing performance.

[0011] In the above-mentioned invention, the cleaning liquid is characterized by having foaming properties. According to this feature, even if the cleaning liquid has foaming properties, foaming is immediately eliminated, so that a stable degassing performance can be obtained.

[0012] In the above-mentioned invention, the vibrator may be characterized in that it vibrates at a frequency higher than the frequency of the ultrasonic wave in the deburring device. With this characteristic, high energy can be applied to obtain stable degassing performance.

[0013] The degassing method according to the present invention is a degassing method using an ultrasonic / vacuum type degassing device incorporated in an ultrasonic deburring system equipped with a deburring device that places a workpiece in a degassed cleaning liquid and removes burrs from the workpiece by a cavity formed by ultrasonic waves, the method comprising: a cylindrical container arranged with a vertical central axis and having an internal closed space whose upper and lower parts are closed by a cover plate and a bottom plate, respectively; a degassing port provided near the upper part of the cylindrical container for evacuating the internal closed space; and a supply pipe provided below the degassing port and on a side wall of the cylindrical container for supplying the cleaning liquid to the internal closed space. The cleaning liquid supply system has a supply port and a discharge port provided in the bottom plate for discharging the cleaning liquid from the internal closed space, and includes a window portion provided below the supply port through the side wall of the cylindrical container, a sealing wall provided to close the window portion, and a vibrator attached to the rear surface of the sealing wall so as to cause the front surface of the sealing wall to reciprocate toward the central axis, and is characterized in that the cleaning liquid is introduced into the cylindrical container so as to raise the water level position at least higher than the window portion, and the vibrator vibrates the sealing wall to radiate compressional waves to the cleaning liquid in the cylindrical container toward the central axis.

[0014] According to this feature, by emitting compressional waves toward the central axis of the cylindrical container, the air bubbles are immediately moved upward and destroyed without being allowed to float in the cleaning liquid, thereby achieving stable degassing performance.

[0015] In the above-mentioned invention, the cleaning liquid is characterized by having foaming properties. According to this feature, even if the cleaning liquid has foaming properties, foaming is immediately eliminated, so that a stable degassing performance can be obtained.

[0016] In the above-mentioned invention, the vibrator may be characterized in that it vibrates at a frequency higher than the frequency of the ultrasonic wave in the deburring device. Also, the vibration frequency may be 50 KHz or more. According to this feature, it is possible to provide high energy and obtain stable degassing performance. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram of an ultrasonic deburring system in which a degassing apparatus according to an embodiment of the present invention is used. [Diagram 2] FIG. 2 is a side view of a degassing device according to an example of the present invention. [Diagram 3] FIG. 2 is an exploded perspective view of a main part of the degassing device. [Figure 4] FIG. 2 is a top cross-sectional view of the degassing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a degassing device as one embodiment of the present invention will be described with reference to Figs. 1 to 4.

[0019] 1, the degassing device 10 is an ultrasonic / vacuum type degassing device, and is incorporated into a deburring system 50. The deburring system 50 includes a deburring device 30 that immerses a workpiece in a degassed cleaning liquid and removes burrs from the workpiece by using a cavity formed by ultrasonic waves.

[0020] In addition to the degassing device 10 and deburring device 30 described above, the deburring system 50 includes a circulation pump 21 for circulating the cleaning liquid supplied from the degassing device 10 within the system, a cooling device 22 for controlling the cleaning liquid supplied to the deburring device 30 at a predetermined temperature, and a purification device 23 for removing impurities from the cleaning liquid used for deburring by the deburring device 30 and discharged, and is equipped with a vacuum pump 29 for drawing a vacuum inside the closed space of the degassing device 10.

[0021] The degassing device 10 is a device that degasses the cleaning liquid to be supplied to the deburring device 30. Details will be described later. The cleaning liquid degassed by the degassing device 10 is sent out by the circulation pump 21, guided to the cooling device 22, adjusted to a predetermined temperature, and supplied to the deburring device 30.

[0022] As described above, the deburring device 30 irradiates ultrasonic waves to the cleaning liquid, generates cavitation in the cleaning liquid, and forms cavities in the cleaning liquid, and deburrs the workpiece by the shock waves caused by the bursting of the cavities. Since deburring is performed by the cavities, it is preferable to form cavities with high energy. Therefore, for example, the deburring device 30 includes two tanks, a cleaning tank 31 and an overflow tank 32. The cleaning tank 31 can maintain a constant liquid level of the cleaning liquid in the cleaning tank 31 by overflowing the cleaning liquid beyond a partition of a predetermined height provided between the cleaning tank 31 and the overflow tank 32. The cleaning tank 31 can irradiate ultrasonic waves from a vibration plate horizontally arranged at the bottom toward the liquid level, and fix the depth at which the cavity is formed by forming standing waves, and can impart relatively high energy to the formed cavity. In this way, the workpiece immersed in the cleaning liquid in the cleaning tank 31 can be deburred.

[0023] The cleaning liquid used in the deburring device 30 is guided to the purifying device 23. The purifying device 23 purifies the cleaning liquid in multiple stages using a plurality of filters (not shown). Since the cleaning liquid discharged from the overflow tank 32 and the cleaning liquid discharged from the cleaning tank 31 are polluted in different ways, multiple stages of filters are provided to correspond to each of them. The cleaning liquid purified by the purifying device 23 is then guided to the degassing device 10 and circulated.

[0024] The deburring system 50 also includes pumps and valves (not shown) so that the flow path and flow rate of the cleaning liquid can be appropriately controlled. A liquid supply port for adding the cleaning liquid is provided in the overflow tank 32 of the deburring device 30, and a liquid drain port for discharging the cleaning liquid outside the deburring system 50 is provided branching off at the rear of the circulating pump 21.

[0025] 2, the degassing device 10 includes a main body 1 which is a substantially cylindrical container, a cover plate 2 which closes an upper part of the main body 1, and a bottom plate 3 which closes a lower part of the main body 1, and is disposed with the central axis V of the main body 1 vertical. The main body 1 includes flanges 1a and 1b at its upper and lower ends, respectively, and the cover plate 2 and the bottom plate 3 are fastened and fixed to the flanges 1a and 1b by bolts and nuts (not shown), respectively. As a result, the degassing device 10 has an internal closed space 1c of the main body 1. The internal closed space 1c is a space for storing the cleaning liquid L and for evacuating the upper side of the liquid surface of the cleaning liquid L, as will be described later.

[0026] The degassing device 10 further includes a degassing port 4 provided near the upper portion of the main body 1 and connected to a vacuum pump 29. This allows the internal closed space 1c to be evacuated through the degassing port 4. A supply port 5 for introducing the cleaning liquid L into the internal closed space 1c is provided below the degassing port 4 on the side wall of the main body 1. In addition, a discharge port 6 for discharging the cleaning liquid L from the internal closed space 1c is provided on the bottom plate 3. Furthermore, an ultrasonic vibrator 11 is provided below the supply port 5.

[0027] Referring also to Figure 3, the main body 1 has a window 12 penetrating the side wall below the supply port 5. The window 12 has a shape in which horizontal cuts of the same depth and in the same direction are made from the side at two locations, top and bottom, of a cylinder, with the ends of both cuts being connected vertically by a straight line (see Figure 3(a) in particular). At this time, it is considered that there is a horizontal line H extending vertically from the central axis V along the direction in which the cuts are made. The window 12 has an annular wall 13 extending along the horizontal line H from near its periphery outward toward the side wall of the main body 1.

[0028] The annular wall portion 13 is fixed, for example, by welding along the periphery of the window portion 12. The annular wall portion 13 is arranged so as to have a substantially rectangular cross-sectional shape when viewed along the horizontal line H, and forms an opening 13a at an extended end portion extending along the horizontal line H. The opening 13a is provided with a flange 14 extending along a plane perpendicular to the horizontal line H around the periphery thereof.

[0029] As shown in Fig. 4, the ultrasonic vibrator 11 has a box-shaped housing, and a wall on one side of the housing is fixed to the flange 14 to form a sealing wall 16 that closes the opening 13a. That is, the sealing wall 16 also closes the window portion 12 through the opening 13a. As described above, the flange 14 is formed along a plane perpendicular to the horizontal line H. Therefore, the sealing wall 16 fixed to the flange 14 is provided along a vertical plane that extends vertically with the horizontal line H as its normal line.

[0030] The ultrasonic vibrator 11 has a plurality of transducers 15 therein. The transducers 15 are attached to the rear surface of the sealing wall 16. The plurality of transducers 15 vibrate in a synchronized manner, thereby causing the front surface of the sealing wall 16 to reciprocate toward the central axis V of the main body 1, and radiating compressional waves that become ultrasonic waves to the cleaning liquid L in front. In particular, by synchronizing the plurality of transducers 15, it is possible to radiate compressional waves having relatively high energy.

[0031] In the degassing device 10, cavitation is generated in the cleaning liquid L by emitting such compressional waves having a relatively high energy. Then, because the pressure in the cavity generated by the cavitation is low, gas components dissolved or suspended in the cleaning liquid are taken in as gas. Then, after the cavity bursts, the gas components remain as bubbles and rise in the cleaning liquid L. The bubbles that rise to the surface of the cleaning liquid L immediately disappear under the low pressure caused by the surrounding vacuum, and the space above is evacuated. In other words, degassing can be performed to remove the gas components from the cleaning liquid L.

[0032] However, if the gas components that have become bubbles in the cleaning liquid L are allowed to float in the cleaning liquid for a long time, they may remain in the cleaning liquid L to be discharged or may be re-dissolved. In other words, the degassing performance may be reduced. Here, according to this embodiment, the sealing wall 16 is provided along a vertical plane (with the normal line of the main surface horizontal), so the vibration direction of the cleaning liquid L, which is the direction of travel of the compressional wave, is horizontal. Therefore, the bubbles that rise in the vertical direction can maintain their rising speed without being affected by the compressional wave with respect to their vertical rising, that is, the bubbles generated by the cavity immediately move upward and disappear at the water surface. This allows the degassing device 10 to obtain stable degassing performance. In addition, even if the cleaning liquid L contains a surfactant and has foaming properties, the bubbles can be immediately caused to rise and disappear, so stable degassing performance can be obtained.

[0033] The annular wall portion 13 has a width W wider than the inner diameter of the main body portion 1, and the blocking wall 16 closing the opening 13a can radiate compressional waves with the same width W. This allows the compressional waves to be radiated over a wider range than the inner cross-sectional shape of the main body portion 1. In other words, cavities can be generated over a wider range, improving the degassing performance.

[0034] Incidentally, if there are bubbles such as microbubbles in the cleaning liquid L, they may act as nuclei to easily generate cavities. Larger bubbles are more likely to become nuclei for generating cavities, and even microbubbles are more likely to generate cavities due to resonance when subjected to ultrasonic waves with the same frequency as the characteristic frequency based on the diameter of the bubbles. If the average pressure, specific heat ratio, and density of the surrounding cleaning liquid L are constant, the product of the characteristic frequency and the diameter of the microbubbles is theoretically a constant value. In other words, by emitting compressional waves with a higher frequency, even smaller microbubbles can be used as nuclei for generating cavities and degassed. Therefore, in the degassing device 10, by increasing the frequency of the ultrasonic vibrator 11, it is possible to easily degas bubbles of a wider range of diameters as cavities, and as a result, the number of cavities generated can be increased and the degassing capacity can be improved.

[0035] On the other hand, in the deburring device 30, as described above, the depth at which the cavity is formed is fixed by forming a standing wave, and a relatively high energy is applied to the formed cavity. However, if microbubbles having a natural frequency close to the frequency of the standing wave are present in the cleaning liquid L, it becomes difficult to fix the depth at which the cavity is formed even by the standing wave. In this case, the cavity is formed at a depth other than the predetermined depth, and sufficient energy cannot be applied to the cavity generated at the predetermined depth, resulting in a loss of deburring ability.

[0036] Therefore, in the degassing device 10, in order to remove many air bubbles including such microbubbles, degassing is performed by using ultrasonic waves with a higher vibration frequency than that of the deburring device 30. In other words, it is preferable that the vibrator 15 is made to vibrate at a higher vibration frequency than that of the ultrasonic waves of the deburring device 30. This makes it possible to suppress the generation of cavities at depths other than the predetermined depth in the deburring device 30, without losing energy used to generate cavities at the predetermined depth. In other words, the deburring performance of the deburring device 30 can be maintained at a high level.

[0037] In the deburring device 30, a vibration frequency of, for example, 20 kHz or 25 kHz is used. In this case, in the degassing device 10, the vibration frequency of the vibrator 15 is preferably 40 kHz or more, and more preferably 50 kHz or more.

[0038] 2 again, the main body 1 of the degassing device 10 is provided with a plurality of sensors each consisting of a level switch for sensing the cleaning liquid L stored in the internal closed space 1c. The sensor S1 is provided at a position higher than the supply port 5 and lower than the degassing port 4, and monitors that the cleaning liquid L does not always reach this height. This allows the position of the liquid level (water level) of the cleaning liquid L to be maintained at a position at least lower than the degassing port 4, and a space for evacuation can be secured. The sensor S4 is provided directly above the upper end of the ultrasonic vibrator 11, and monitors that the cleaning liquid L is always present. This allows the position of the water level to be maintained at a position at least higher than the window portion 12. In other words, the sensors S1 and S4 function as safety devices when the degassing device 10 is operated.

[0039] On the other hand, a sensor S2 is provided at a position lower than the supply port 5, and a sensor S3 is provided at a position lower than the sensor S2 and higher than the sensor S4. Then, under normal circumstances, the flow rates of the cleaning liquid at the supply port 5 and the discharge port 6 are adjusted so that the position of the water surface is kept between the sensors S2 and S3. In other words, when the sensor S3 detects the cleaning liquid L, the valve is operated so that the flow rate is greater at the discharge port 6 than at the supply port 5, and when the sensor S3 no longer detects the cleaning liquid L, the valve is operated so that the flow rate is greater at the supply port 5 than at the discharge port 6. This allows the water surface position of the cleaning liquid L to be maintained at a height within a certain range.

[0040] In this way, by maintaining the water surface position of the cleaning liquid L within a certain range, the pressure applied to the sealing wall 16 of the ultrasonic vibrator 11 can be maintained within a certain range. Since the sealing wall 16 vibrates to radiate compressional waves to the cleaning liquid L, if the pressure received from the cleaning liquid L is too high, the vibration is hindered, and if it is too low, the energy of the vibration is not transmitted sufficiently. Therefore, it is preferable to maintain the pressure applied to the sealing wall 16 within a certain range so that compressional waves of relatively high energy can be radiated.

[0041] Although the embodiments of the present invention and modifications based thereon have been described above, the present invention is not necessarily limited to these examples. In addition, a person skilled in the art will be able to find various alternative embodiments and modifications without departing from the spirit of the present invention or the scope of the appended claims. [Explanation of symbols]

[0042] 1. Main body (cylindrical container) 10 Deaeration device 11 Ultrasonic vibrator 12 Window section 15 Transducers 16 Blockade Wall 30 Deburring device 50 Deburring System

Claims

1. An ultrasonic / vacuum degassing device to be incorporated in an ultrasonic deburring system including a deburring device that removes burrs from a workpiece by inserting the workpiece into a degassed cleaning liquid and forming a cavity by ultrasonic waves, a cylindrical container having an internal closed space with its central axis vertically disposed and its upper and lower ends closed by a cover plate and a bottom plate, respectively; a deaeration port provided near the upper portion of the cylindrical container for evacuating the internal closed space; a supply port provided in a side wall of the cylindrical container below the degassing port and configured to supply the cleaning liquid to the internal closed space; a drain port provided in the bottom plate for draining the cleaning liquid from the internal closed space, a window portion provided below the supply port and penetrating the side wall of the cylindrical container; A sealing wall provided to close the window portion; a vibrator attached to a rear surface of the sealing wall so as to reciprocate a front surface of the sealing wall toward the central axis.

2. The degassing device for an ultrasonic deburring system as described in claim 1, characterized in that the cylindrical container is cylindrical, has an annular wall extending from the periphery of the window portion toward the outside of the side wall along a horizontal line extending vertically from the central axis, and the extending end of the annular wall is closed so that the sealing wall is provided along a vertical plane with the horizontal line as a normal.

3. 2. The degassing device for an ultrasonic deburring system according to claim 1, wherein the cleaning liquid has foaming properties.

4. 4. The degassing device for an ultrasonic deburring system according to claim 1, wherein the vibrator vibrates at a frequency higher than a frequency of the ultrasonic waves in the deburring device.

5. A degassing method using an ultrasonic / vacuum type degassing device incorporated in an ultrasonic deburring system including a deburring device that removes burrs from a workpiece by inserting the workpiece into a degassed cleaning liquid and forming a cavity by ultrasonic waves, comprising: a cylindrical container having an internal closed space with its central axis vertically disposed and its upper and lower ends closed by a cover plate and a bottom plate, respectively; a deaeration port provided near the upper portion of the cylindrical container for evacuating the internal closed space; a supply port provided in a side wall of the cylindrical container below the degassing port and configured to supply the cleaning liquid to the internal closed space; a drain port provided in the bottom plate for draining the cleaning liquid from the internal closed space, a window portion provided below the supply port and penetrating the side wall of the cylindrical container; A sealing wall provided to close the window portion; a vibrator attached to a rear surface of the sealing wall so as to reciprocate a front surface of the sealing wall toward the central axis, A degassing method for an ultrasonic deburring system, characterized in that the cleaning liquid is introduced into the cylindrical container so that the water level is at least higher than the window portion, and the vibrator vibrates the sealing wall to radiate compressional waves into the cleaning liquid in the cylindrical container toward the central axis.

6. The degassing method for an ultrasonic deburring system according to claim 5, wherein the cleaning liquid has foaming properties.

7. 7. The degassing method for an ultrasonic deburring system according to claim 5, wherein the vibrator vibrates at a frequency higher than a frequency of the ultrasonic waves in the deburring device.

8. The degassing method for an ultrasonic deburring system according to claim 7, wherein the vibration frequency is 50 KHz or more.

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