EP3178561A1

EP3178561A1 - Discharge crushing device and discharge crushing method

Info

Publication number: EP3178561A1
Application number: EP16196401.0A
Authority: EP
Inventors: Yuichi Hata; Syougo Utumi; Genichiro Matsuda; Takashi Nakamura; Mingyu SUN
Original assignee: Panasonic Corp
Current assignee: Panasonic Corp
Priority date: 2015-12-08
Filing date: 2016-10-28
Publication date: 2017-06-14
Anticipated expiration: 2036-10-28
Also published as: CN106853410B; JP2017104790A; CN106853410A; EP3178561B1; JP6339994B2

Abstract

The present disclosure provides a discharge crushing device and a discharge crushing method which are highly efficient with a small loss of energy. The discharge crushing device is configured to crush, by pulse discharge, an object to be crushed mounted on a processing target held between upper and lower electrodes, and is characterized as follows. Specifically, the discharge crushing device includes a container to be filled with liquid, an upper electrode and a lower electrode disposed in the liquid in the container, a pulse power source configured to generate pulse discharge by applying a high voltage pulse between the upper electrode and the lower electrode, and an air bubble generation device configured to generate air bubbles in the liquid. The object to be crushed is disposed on a lower surface of processing target, and the air bubbles exist in the liquid on the lower surface of processing target.

Description

BACKGROUND

1. Technical Field

The present disclosure relates to a discharge crushing device and a discharge crushing method that crush an object by pulse power discharge, and particularly relates to a discharge crushing device and a discharge crushing method that crush a used electrical product.

2. Description of the Related Art

Various kinds of work are required for recycling used home appliances and the like. In dismantling, it is required to individually disassemble various forms of screw fastening parts and soldering parts, which makes it difficult to achieve automation, and thus manual dismantling by a worker is mainly employed. The manual dismantling provides the flexibility of work but has low operation efficiency, and thus it has been desired to develop a method of automatically and efficiently dismantling various kinds of used home appliances.
PTL 1 discloses a method in which materials to be recycled, including ceramic components such as a battery and a fuse, computer components, and capacitors are placed still in a reaction container filled with liquid, and pulse discharge is generated between a plurality of electrode rods and a container substrate provided in the liquid so as to destroy plastic exteriors and the like. PTL 2 discloses a method for pulse discharge crushing, in which liquid between electrodes is filled with air bubbles before discharge, and water hammer pressure is generated by cavitation collapse of the air bubbles, which is caused by shock wave generated by pulse discharge, thereby achieving highly efficient crushing.

Citation List

Patent Literature

PTL 1: Japanese Translation of PCT Publication 2014-532548
PTL 2: Unexamined Japanese Patent Publication No. 10-57832

However, when air bubbles exist at a position distant from a processing target on a discharge path or between the discharge path and the processing target in liquid, a loss of energy of high-voltage pulse discharge is caused by water hammer pressure generated by cavitation collapse of the air bubbles.

SUMMARY

The present disclosure is intended to solve such a problem and an object thereof is to provide a discharge crushing device and a discharge crushing method which are highly efficient with a small loss of energy.
To solve the above-described problem, a discharge crushing device according to an aspect of the present disclosure is configured to crush, by pulse discharge, an object to be crushed mounted on a processing target held between upper and lower electrodes, and includes the following configuration. Specifically, the discharge crushing device includes: a container holding liquid; the upper electrode and the lower electrode disposed in the liquid in the container; a pulse power source configured to generate pulse discharge by applying a high voltage pulse between the upper electrode and the lower electrode; and an air bubble generation device configured to generate air bubbles on a lower surface side of the processing target held between the upper and lower electrodes in the liquid so that the object to be crushed is disposed on a lower surface of the processing target. When the pulse power source applies a high voltage pulse between the upper electrode and the lower electrode, the object to be crushed is crushed by shock wave due to collapsing and disappearing of air bubbles generated by the pulse discharge, the air bubbles existing on the lower surface side of the processing target.
A discharge crushing device according to another aspect of the present disclosure is configured to crush, by pulse discharge, an object to be crushed mounted on a processing target held between upper and lower electrodes, and includes the following configuration. Specifically, the discharge crushing device includes: a container holding liquid; a ground electrode connected with the processing target disposed in the liquid in the container; a pair of positive electrodes disposed facing each other so as to sandwich the processing target; a discharge circuit configured to cause the pair of positive electrodes to alternately perform pulse discharge. After discharge at one of the pair of positive electrodes, air bubbles are generated on a one positive electrode side of the processing target, and the discharge circuit performs discharge at another of the pair of positive electrodes while the air bubbles exist on the one positive electrode side of the processing target, to crush the object to be crushed by shock wave due to collapsing and disappearing of the air bubbles generated by the discharge at the one positive electrode.
A discharge crushing method according to another aspect of the present disclosure crushes, by pulse discharge, an object to be crushed mounted on a processing target held between upper and lower electrodes in liquid, and includes the following configuration. Specifically, the method includes: while air bubbles exist on a lower surface side of the processing target, generating pulse discharge by applying a high voltage pulse between the upper and lower electrodes in the liquid to crush the object to be crushed by shock wave due to collapsing and disappearing of air bubbles generated by the pulse discharge.
A discharge crushing method according to another aspect of the present disclosure includes generating pulse discharge by applying a high voltage pulse between a positive electrode and a ground electrode in liquid to crush, by shock wave generated at the pulse discharge, an object to be crushed on a processing target disposed in a range to which the shock wave travels, and includes the following configuration. Specifically, the method includes: when the high voltage pulse is applied while the ground electrode is provided in contact with the processing target, and a pair of the positive electrodes are disposed facing each other so as to sandwich the processing target, generating air bubbles by discharge at one of the pair of positive electrodes to crush an object to be crushed disposed on a one positive electrode side of the processing target, by shock wave due to collapsing and disappearing of the air bubbles generated by the discharge at the one positive electrode; and generating air bubbles by discharge at another of the pair of positive electrodes to crush an object to be crushed disposed on an another positive electrode side of the processing target, by shock wave due to collapsing and disappearing of the air bubbles generated by the discharge at the one positive electrode.
The aspects of the present disclosure provide a discharge crushing device and a discharge crushing method which can highly efficiently crush an object to be recycled, in particular, a used home appliance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a configuration of a discharge crushing device according to a first exemplary embodiment;
FIG. 2 is a diagram illustrating a configuration of a discharge crushing device according to a second exemplary embodiment;
FIG. 3 is a diagram illustrating a configuration of a discharge crushing device according to a third exemplary embodiment;
FIG. 4 is a diagram illustrating a configuration of a discharge crushing device according to a fourth exemplary embodiment;
FIG. 5 is a partial sectional view of the discharge crushing device according to the fourth exemplary embodiment taken along line A-A' in FIG. 4; and
FIG. 6 is a diagram illustrating a configuration of a discharge crushing device according to a fifth exemplary embodiment.

DETAILED DESCRIPTION

Exemplary embodiments the present disclosure will be described below with reference to the accompanying drawings.

FIRST EXEMPLARY EMBODIMENT

First, a configuration of discharge crushing device 1 and a discharge crushing method using discharge crushing device 1 according to a first exemplary embodiment are described below with reference to FIG. 1. FIG. 1 is a diagram illustrating the configuration of the discharge crushing device according to the first exemplary embodiment.
Discharge crushing device 1 is configured to crush, by pulse discharge, an object to be crushed mounted on a processing target held between upper and lower electrodes. As illustrated in FIG. 1, discharge crushing device 1 includes container 20 filled with water 10, upper electrode 31 and lower electrode 32 disposed in the liquid, pulse power source 40 configured to apply a high voltage pulse to upper electrode 31, and air bubble generation device 50 configured to generate water flow containing air bubbles 80 (hereinafter referred to as air bubble water flow). Upper electrode 31 is connected with pulse power source 40 and lead wire 33a, and lower electrode 32 is grounded through lead wire 33b. Upper electrode 31 and lower electrode 32 face to each other so as to sandwich the processing target 60. Processing target 60 is supported between upper electrode 31 and lower electrode 32 by a supporting unit (not illustrated), and has a lower surface on which object to be crushed 70 is mounted. Thus, object to be crushed 70 is disposed in a range to which shock wave generated at pulse discharge travels. Air bubble generation device 50 is connected with inflow path 12a including an inflow tube disposed toward the lower surface of processing target 60 from a bottom surface of container 20. Air bubble generation device 50 is configured to inject air-bubble-containing liquid from below processing target 60 through inflow path 12a. Ejection path 13a and ejection path 13b, each including an outflow tube disposed from the lower surface of processing target 60 toward the bottom surface of container 20, are provided below processing target 60. Water 10 is sucked and ejected from container 20 by pump 51 as an exemplary liquid suction device connected with ejection path 13a and ejection path 13b.
Pulse power source 40 only needs to be capable of applying voltage up to 500 kV and outputting discharge current of 30 kA at maximum for a pulse width of 3 µsec, and may be a Marx generator. A preferable discharge condition varies depending on a kind and a size of an object, but the pulse width is preferably 1 µsec to 9 µsec, and the discharge current is preferably 10 kA to 30 kA. A number of times to generate discharge (number of times of pulsing) is preferably 1 to 100. More than 100 times of pulsing results in a longer processing time, which is disadvantage in man-hour. A pulse frequency is not particularly limited, but is typically 1 Hz to 5 Hz.
Air bubble generation device 50 is not particularly limited as long as the device can generate an air bubble having a diameter of 3 mm or smaller. Air bubble generation device 50 may be, for example, an air-liquid mixing device provided with an air-liquid mixing nozzle, an air-liquid two-phase rotation type configured to generate air-bubble-containing liquid by stirring gas in liquid to be mixed, or a pressurized dissolving type configured to dissolve gas into liquid through pressurization.
In the first exemplary embodiment, leading ends of upper electrode 31 and lower electrode 32 each have a circular cone shape. Lower electrode 32 may be formed in various shapes. Lower electrode 32 may have, for example, a flat plate shape, a reticular shape, a lattice shape, or a spiral shape instead of the circular cone shape as illustrated in FIG. 1.
Processing target 60 is not particularly limited, but is preferably a thin object so that the entire object is equally provided with an effect of shock wave due to discharge. Examples of processing target 60 include a circuit board used in an electrical product such as a cellular phone, a game machine, or a flat-panel television. Examples of object to be crushed 70 mounted on the lower surface of processing target 60 include an electric component soldered to a circuit board, such as an IC chip or a chip component.
The following describes an effect of discharge crushing device 1 having the above configuration.
Air bubble generation device 50 is actuated to inject air-bubble-containing liquid toward substantially a center of the lower surface of processing target 60 through inflow path 12a disposed in a lower part of container 20. The air-bubble-containing liquid injected to substantially the center of the lower surface collides against processing target 60, and radially flows in end-face directions (right and left directions in FIG. 1) from substantially the center of the lower surface of processing target 60. Since ejection path 13a and ejection path 13b are provided in the lower part of container 20 (for example, below vicinities of end faces), the air-bubble-containing liquid flowing in each end-face direction of processing target 60 flows toward the lower part of container 20 due to an ejection function through ejection path 13a and ejection path 13b. This prevents the air bubbles from flowing around to an upper surface side of processing target 60, and as a result, the air bubbles hardly exist on the upper surface side of processing target 60 but exist on the lower surface side of processing target 60.
In this state, pulse power source 40 is driven. A high voltage pulse generated by pulse power source 40 is applied between upper electrode 31 and lower electrode 32. Discharge occurs between upper electrode 31 and lower electrode 32. Accordingly, since processing target 60 is disposed between upper electrode 31 and lower electrode 32, creeping discharge occurs in which discharge creeps around from the upper surface of processing target 60 to the lower surface. Shock wave generated by this creeping discharge provides energy to air bubbles 80 on the lower surface of processing target 60. Accordingly, air bubbles 80 each expand, and stop expanding and then start contracting when an inside pressure of the air bubble becomes lower than water pressure. The contraction increases the inside pressure, and finally, the air bubble collapses and disappears. At a moment of the collapsing and disappearing of air bubbles 80, abrupt pressure wave called bubble pulse (hereinafter referred to as bubble shock wave) is generated. Consequently, the shock wave generated by creeping discharge and the bubble shock wave are superposed with each other, thereby efficiently crushing object to be crushed 70 mounted on the lower surface of processing target 60. Since discharge crushing device 1 has the configuration in which the air-bubble-containing liquid generated by air bubble generation device 50 is prevented from flowing around to the upper surface side of processing target 60, a small number of air bubbles 80 exist between upper electrode 31 and processing target 60. Thus, energy generated by the discharge is less likely to be consumed as energy for expanding air bubbles 80, before arriving at processing target 60. This configuration enables more efficient discharge crushing. For example, when object to be crushed 70 is directly crushed only by shock wave, a high voltage pulse at approximately 250 kV is required. In the exemplary embodiment of the present disclosure, however, the use of the bubble shock wave enables crushing with a high voltage pulse at approximately 100 kV, which leads to downsizing of pulse power source 40, thereby achieving highly efficient crushing processing at low cost.
Each air bubble 80 preferably has a diameter of 50 µm to 3 mm, and most preferably, a diameter of 100 µm to 1 mm. When the air bubble has a diameter in these ranges, the shock wave due to discharge can expand air bubbles 80 efficiently.
The number of air bubbles generated by air bubble generation device 50 is preferably controlled to be in a range from 100 to 10000 per cubic centimeter on the lower surface of processing target 60. Controlling the number of air bubbles in this range can maximally enhance a crushing force generated by the superposition of the shock wave due to discharge and the bubble shock wave. In contrast, it is preferable that the number of generated air bubbles on the upper surface side of processing target 60 is as small as possible, and that no air bubble has a diameter of 50 µm or larger.
In the first exemplary embodiment, the air-bubble-containing liquid is injected to substantially the center of the lower surface of processing target 60. However, as long as air bubbles diffuse uniformly on the entire lower surface, the air-bubble-containing liquid is not limited to be injected to a vicinity of the center.
In order to maintain a constant water level of container 20, an amount of liquid ejected through ejection path 13a and ejection path 13b is equal to an amount of air-bubble-containing liquid flowing through inflow path 12a.
The "lower surface" of processing target 60 includes a region 7.5 mm below the actual lower surface of processing target 60. When an amount of air bubbles in this region is larger than an amount of air bubbles on the upper surface side of the processing target (for example, in a region between the upper surface of processing target 60 and a lower end of the upper positive electrode), the superposition of the shock wave and the bubble shock wave is effectively achieved.
Thus, a leading end part of inflow path 12a through which air-bubble-containing liquid is introduced into container 20, in other words, an inlet opening for air-bubble-containing liquid, is preferably installed at a position 7.5 mm to 150 mm below the actual lower surface of processing target 60.
A speed at which air-bubble-containing liquid flows in through inflow path 12a is preferably 100 cm³ to 1500 cm³ per second.
The discharge crushing device and the discharge crushing method according to the first exemplary embodiment of the present disclosure can highly efficiently crush a recycle target object, in particular, a used home appliance. This effect can be at least achieved by each exemplary embodiment described below.

SECOND EXEMPLARY EMBODIMENT

Next, a configuration of discharge crushing device 2 and a discharge crushing method using discharge crushing device 2 according to a second exemplary embodiment are described below with reference to FIG. 2. FIG. 2 is a diagram illustrating the configuration of the discharge crushing device according to the second exemplary embodiment. Discharge crushing device 2 according to the second exemplary embodiment is configured by further providing discharge crushing device 1 according to the first exemplary embodiment with liquid inflow path 14. Any element identical to a corresponding element of discharge crushing device 1 is denoted by an identical reference numeral. The air bubble formation condition in the first exemplary embodiment is similarly applied in the second exemplary embodiment.
As illustrated in FIG. 2, in discharge crushing device 2 according to the second exemplary embodiment, liquid inflow path 14 including a liquid inflow tube inserted downward is provided in an upper part of container 20. Water 10 containing no air bubbles is transferred from pump 52 as an exemplary liquid transferring device, is injected through an outlet opening of liquid inflow path 14 disposed in water 10 in container 20, and collides against a substantially central part of the upper surface of processing target 60. Water 10, which has collided against the substantially central part of the upper surface of processing target 60, flows radially in each end-face direction of processing target 60.
The following describes an effect of discharge crushing device 2 having the above configuration.
It is important that no air bubbles 80 exist between upper electrode 31 and the upper surface of processing target 60 to prevent energy generated by discharge from being consumed as energy for expanding air bubbles 80 before arriving at processing target 60. Water 10 containing no air bubbles, which is injected through the outlet opening of liquid inflow path 14, flows radially in each end-face direction of processing target 60. Accordingly, air bubbles 80 are prevented from flowing around the vicinities of the end faces of processing target 60 to the upper surface side of processing target 60. When processing target 60 is a circuit board, a hole penetrating through an upper surface and a lower surface of the circuit board, for example, a through-hole, may be formed in the circuit board. When the circuit board is provided with the through-hole, air bubbles 80 may flow upward to the upper surface side of processing target 60 through this through-hole. In discharge crushing device 2 according to the second exemplary embodiment, however, water 10 containing no air bubbles is injected through the outlet opening of liquid inflow path 14 and is caused to collide against the upper surface of processing target 60. With this configuration, a water pressure of injected water 10 can prevent air bubbles 80 from passing through the through-hole of processing target 60, and can also remove, from the upper surface side, any air bubble having passed through the through-hole.
Water containing air bubbles and water containing no air bubbles are ejected from discharge crushing device 2 through ejection path 13a and ejection path 13b. The number of generated air bubbles is preferably controlled to be 100 to 10000 per cubic centimeter on the lower surface of processing target 60.

THIRD EXEMPLARY EMBODIMENT

Next, a configuration of discharge crushing device 3 and a discharge crushing method using discharge crushing device 3 according to a third exemplary embodiment are described below with reference to FIG. 3. FIG. 3 is a diagram illustrating the configuration of the discharge crushing device according to the third exemplary embodiment. Discharge crushing device 3 according to the third exemplary embodiment includes components same as those of discharge crushing device 1 according to the first exemplary embodiment, and is different from discharge crushing device 1 in arrangement of an inflow path and an ejection path. Any element identical to a corresponding element of discharge crushing device 1 is denoted by an identical reference numeral. The air bubble formation condition in the first exemplary embodiment is similarly applied in the third exemplary embodiment.
As illustrated in FIG. 3, in discharge crushing device 3 according to the third exemplary embodiment, inflow path 12b and ejection path 13c are provided to side surfaces of container 20. Inflow path 12b is connected with air bubble generation device 50, and ejection path 13c is connected with pump 51 as an exemplary liquid suction device. Inflow path 12b and ejection path 13c are aligned on a substantially identical axis below processing target 60. Air-bubble-containing liquid injected through inflow path 12b flows along the lower surface side of processing target 60, and is ejected out of container 20 through ejection path 13c.
In this manner, according to the third exemplary embodiment, air bubbles 80 flow along the lower surface side of processing target 60, and thus is prevented from flowing around to the upper surface of processing target 60.

FOURTH EXEMPLARY EMBODIMENT

Next, a configuration of discharge crushing device 4 and a discharge crushing method using discharge crushing device 4 according to a fourth exemplary embodiment are described below with reference to FIGS. 4 and 5.
FIG. 4 is a diagram illustrating the configuration of the discharge crushing device according to the fourth exemplary embodiment, and FIG. 5 is a partial sectional view of discharge crushing device 4 taken along line A-A' in FIG. 4. The configuration according to the fourth exemplary embodiment is the same as the configuration of the third exemplary embodiment except for channel 90. The air bubble formation condition in the first exemplary embodiment is similarly applied in the fourth exemplary embodiment.
As illustrated in FIG. 4, discharge crushing device 4 according to the fourth exemplary embodiment is provided with channel 90 on the lower surface of processing target 60. As illustrated in FIG. 5, channel 90 has a substantially U-shaped section and a length shorter than a length of processing target 60 in a direction in which air bubbles 80 flow. When processing target 60 is held such that the lower surface of processing target 60 covers an opening of channel 90, object to be crushed 70 mounted on the lower surface of processing target 60 is disposed in channel 90. With this configuration, air bubbles 80 flow in a space enclosed by the lower surface of processing target 60 and channel 90, and thus can be prevented from flowing around to the upper surface of processing target 60. Channel 90 is preferably made of an electrically insulating material. The electrically insulating material is, for example, plastic. An electrically insulating material is preferable because, when channel 90 is made of an electrically conducting material, discharge occurs between upper electrode 31 and channel 90, and thus creeping discharge flows a shorter distance along the lower surface of processing target 60, which leads to reduction in generation of the shock wave due to discharge over the entire lower surface of processing target 60.
A distance between a bottom surface of channel 90 and the lower surface of processing target 60 is preferably in a range from 40 mm to 200 mm. This range allows the superposition of the shock wave and the bubble shock wave to occur effectively without increase in a size of the device.

FIFTH EXEMPLARY EMBODIMENT

Next, a configuration of discharge crushing device 5 and a discharge crushing method using discharge crushing device 5 according to a fifth exemplary embodiment are described below with reference to FIG. 6.
FIG. 6 is a diagram illustrating the configuration of the discharge crushing device according to the fifth exemplary embodiment. In discharge crushing device 5 according to the fifth exemplary embodiment, processing target 60 is held in liquid, ground electrode 101 is provided so as to make contact with processing target 60, and a pair of positive electrodes 100a and 100b are provided spaced apart from each other and facing different surfaces of processing target 60. Discharge crushing device 5 also includes discharge circuit 53 configured to cause positive electrodes 100a and 100b to alternately perform pulse discharge. Objects 70a and 70b to be crushed are mounted on the upper surface and the lower surface of processing target 60, respectively.
Since air bubbles are generated after discharge, the alternate discharge with positive electrodes 100a and 100b can achieve enhancement of the crushing force by using bubbles generated by last discharge on an opposite surface of processing target 60.
Since air bubbles collapse by shock wave generated at a moment of discharge, air bubbles, on a side on which an electrode that is about to perform next discharge is disposed, collapse and disappear by last discharge generated on an opposite surface of processing target 60, and thus a discharge path can be maintained in a state with no air bubbles, thereby preventing current attenuation along the discharge path.
In this manner, air bubbles exist on one of the surfaces, on which an object to be crushed exists, of processing target 60 by discharge, whereas air bubbles hardly exist on the other surface (on which discharge occurs), thereby maintaining the discharge path in a state with no air bubbles.
A discharge waveform preferably has a discharge current peak value of 10 kA or larger so as to, for example, remove an electric component from an electronic substrate.
When positive electrodes 100a and 100b are located above and below processing target 60 so as to sandwich processing target 60, a time from discharge at positive electrode 100a located on the upper side until discharge at positive electrode 100b located on the lower side is preferably set to be a time until air bubbles existing on the upper surface of processing target 60 move upward beyond a range in which the air bubbles contribute to crushing. As for this time, since a moving speed is approximately 100 mm per second at maximum due to buoyancy of a large number of air bubbles, each having a diameter of 3 mm or smaller, generated by discharge and water flow caused by the discharge, and since it is assumed that crushing energy is high in a range twice as large as the bubble diameter, it is calculated that discharge at lower positive electrode 100b is preferably generated in 0.05 seconds or less after discharge at upper positive electrode 100a. In this case, a time after discharge at lower positive electrode 100b until discharge at upper positive electrode 100a is not particularly important because generated air bubbles are accumulated on the surface of processing target 60, which eliminates the need to consider the moving speed of bubbles.
According to the fifth exemplary embodiment, for example, discharge circuit 53 first causes one of the positive electrodes, for example, upper positive electrode 100a to perform pulse discharge. After the pulse discharge, air bubbles are generated on an upper positive electrode side, that is, the upper surface side of processing target 60.
Thereafter, discharge circuit 53 causes the other positive electrode, for example, lower positive electrode 100b to perform pulse discharge. The air bubbles generated on the upper surface side of processing target 60 after the pulse discharge at upper positive electrode 100a are used to crush object 70a to be crushed on the upper surface side of processing target 60 by shock wave due to collapsing and disappearing of the air bubbles.
Thereafter, after pulse discharge at lower positive electrode 100b, air bubbles are generated on a lower positive electrode side, that is, the lower surface side of processing target 60.
Thereafter, discharge circuit 53 causes upper positive electrode 100a to perform pulse discharge. The air bubbles generated on the lower surface side of processing target 60 after the pulse discharge at lower positive electrode 100b are used to crush object 70b to be crushed on the lower surface side of processing target 60 by shock wave due to collapsing and disappearing of the air bubbles.
In this manner, discharge circuit 53 causes a pair of positive electrodes 100a and 100b to alternately perform pulse discharge to generate air bubbles, and then the generated air bubbles are used to crush objects 70a and 70b to be crushed on processing target 60 by shock wave due to collapsing and disappearing of the air bubbles caused by pulse discharge generated on a side opposite to a side on which the air bubbles are generated.
Thus, according to the fifth exemplary embodiment, a pair of positive electrodes 100a and 100b, ground electrode 101, and discharge circuit 53 configure an air bubble generation device also serving as a pulse discharge device.
An effect provided by each exemplary embodiment or modification can be achieved by combining optional exemplary embodiments or modifications among the above-described various exemplary embodiments or modifications as appropriate. A combination of exemplary embodiments, a combination of examples, or a combination of an exemplary embodiment and an example is possible, and also a combination of features in different exemplary embodiments or examples is possible.
The discharge crushing device and the discharge crushing method according to the above aspects of the present disclosure are useful as a discharge crushing device and a discharge crushing method that can highly efficiently crush an object to be recycled, in particular, a used home appliance.

Claims

A discharge crushing device configured to crush, by pulse discharge, an object to be crushed mounted on a processing target held between upper and lower electrodes, the device comprising:
a container holding liquid;

the upper electrode and the lower electrode disposed in the liquid in the container;

a pulse power source configured to generate pulse discharge by applying a high voltage pulse between the upper electrode and the lower electrode; and

an air bubble generation device configured to generate air bubbles on a lower surface side of the processing target held between the upper and lower electrodes in the liquid so that the object to be crushed is disposed on a lower surface of the processing target,

wherein, when the pulse power source applies a high voltage pulse between the upper electrode and the lower electrode, the object to be crushed is crushed by shock wave due to collapsing and disappearing of air bubbles generated by the pulse discharge, the air bubbles existing on the lower surface side of the processing target.
The discharge crushing device according to claim 1, wherein the air bubble generation device is a pump configured to cause liquid containing air bubbles to flow in from the lower surface side of the processing target.
The discharge crushing device according to claim 1 or 2, further comprising a liquid suction device configured to suck, from the lower surface side of the processing target, liquid containing air bubbles having collided against the processing target.
The discharge crushing device according to claim 1, wherein the air bubble generation device is a pump configured to cause liquid containing the air bubbles to flow in along the lower surface side of the processing target.
The discharge crushing device according to any one of claims 1 to 4, further comprising a liquid transferring device configured to cause liquid containing no air bubbles to flow in from an upper surface side of the processing target and cause the liquid to collide against the processing target.
The discharge crushing device according to any one of claims 1 to 5, wherein the liquid is water.
The discharge crushing device according to any one of claims 1 to 6, wherein the processing target is a circuit board.
A discharge crushing device configured to crush, by pulse discharge, an object to be crushed mounted on a processing target held between upper and lower electrodes, the device comprising:
a container holding liquid;

a ground electrode connected with the processing target disposed in the liquid in the container;

a pair of positive electrodes disposed facing each other so as to sandwich the processing target; and

a discharge circuit configured to cause the pair of positive electrodes to alternately perform pulse discharge,

wherein, after discharge at one of the pair of positive electrodes, air bubbles are generated on a one positive electrode side of the processing target, and the discharge circuit performs discharge at another of the pair of positive electrodes while the air bubbles exist on the one positive electrode side of the processing target, to crush the object to be crushed by shock wave due to collapsing and disappearing of the air bubbles generated by the discharge at the one positive electrode.
A discharge crushing method of crushing, by pulse discharge, an object to be crushed mounted on a processing target held between upper and lower electrodes in liquid, the method comprising, while air bubbles exist on a lower surface side of the processing target, generating pulse discharge by applying a high voltage pulse between the upper and lower electrodes in the liquid to crush the object to be crushed by shock wave due to collapsing and disappearing of air bubbles generated by the pulse discharge.
A discharge crushing method including generating pulse discharge by applying a high voltage pulse between a positive electrode and a ground electrode in liquid to crush, by shock wave generated at the pulse discharge, an object to be crushed on a processing target disposed in a range to which the shock wave travels, the method comprising:
when the high voltage pulse is applied while the ground electrode is provided in contact with the processing target, and a pair of the positive electrodes are disposed facing each other so as to sandwich the processing target,

generating air bubbles by discharge at one of the pair of positive electrodes to crush an object to be crushed disposed on a one positive electrode side of the processing target, by shock wave due to collapsing and disappearing of the air bubbles generated by the discharge at the one positive electrode; and

generating air bubbles by discharge at another of the pair of positive electrodes to crush an object to be crushed disposed on an another positive electrode side of the processing target, by shock wave due to collapsing and disappearing of the air bubbles generated by the discharge at the one positive electrode.