JP3814718B2 - Microsphere sorting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sphere sorting device that sorts defective spheres (deformed spheres) mixed in non-defective spheres (true spheres) using the difference in rolling conditions on a slope.
[0002]
[Prior art]
FIG. 4 shows main deformed spheres included in the microspheres manufactured by the atomizing method. In the figure, (a) is called a twin sphere, and (b) is called a parent-child sphere. (C) is also a kind of twin sphere.
[0003]
Microspheres are also used in electronic devices, optical fiber related products, and the like, and in such applications, true spheres are required. Therefore, selective removal of deformed spheres is indispensable.
[0004]
However, many of the deformed spheres as shown in FIG. 4 have an outer diameter in a specific direction equal to the non-defective diameter, and cannot be removed by a sieve sorter using a mesh screen or a roller sorter that performs sorting using a gap between rollers. Sometimes.
[0005]
As shown in FIG. 5A, when the sphere B is placed on the flat inclined plate 1, the true sphere rolls straight, whereas the deformed sphere has a difference in circumference at the contact portion with the inclined plate. When it is placed diagonally on the inclined plate, it rolls diagonally as shown in FIG. There is a tilt sorting method that sorts by the difference in the rolling direction. However, as shown in FIG. 5 (c), this method uses a cylinder if the twin spheres have the same diameter and the posture on the tilt plate is not tilted. It becomes the same situation as rolling, the deformed sphere rolls down straight and remains in the sphere.
[0006]
Therefore, the present applicant has provided a vertical groove that gives direction to the movement of the sphere, and an inclination selection method using the difference in flight distance between a true sphere that rolls in the groove and a deformed sphere that slides while the rolling is restricted. A device capable of removing the deformed spheres that could not be sorted out in the above is developed and proposed in Japanese Patent Application No. 2000-121124.
[0007]
With the development of the device, spheres of up to about 0.3 mm can be selected well, but for spheres smaller than that, some spheres adhere to the inclined plate and the spheres adsorb each other. A matching phenomenon also occurred, and the movement on the inclined plate stopped, and the subsequent flow of the sphere was blocked, making it impossible to perform proper sorting. In addition, if the inclination of the inclined plate is set to a high angle, a clear difference does not appear in the rolling direction and the flight distance between the true sphere and the deformed sphere, and the selection becomes difficult. .
[0008]
For this reason, selection of spheres having a diameter smaller than about 300 μm is still performed by visual inspection.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to make it possible to automatically sort such microspheres in order to save labor.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, in the present invention, a flat inclined plate on which microspheres are placed and rolled, and a vibration source that vibrates the inclined plate are provided, and the inclination angle of the inclined plate is 3 degrees to 10 degrees. The present invention provides a microsphere sorting device in which the frequency is 300 Hz to 500 Hz, and the upper surface of the inclined plate has an appropriate surface roughness and has a surface on which numerous fine streaks extending in the vertical direction are observed. .
[0011]
The apparatus of tilt swash plate, those formed of a material of the same material as the spheres are screened, those having a conductive film for grounding the processing on the upper surface of the inclined plate, or to form a excitation source electrostrictive element It is preferable to apply a sinusoidal vibration to the inclined plate.
[0012]
Also, a deformed sphere is provided which has a vertical groove that gives a direction to movement of the sphere by inserting a microsphere on the front end side of the inclined plate, and further drops a deformed sphere that slides restrained by the vertical groove from the front end of the inclined plate. It is also preferable to add a collection part and a sorting plate for guiding the true sphere rolling down in the longitudinal groove and falling in front of the deformed sphere collection part to the true sphere collection part.
[0013]
[Action]
According to experts, the reason why microspheres with a diameter of around 300 μm or less stay on the inclined plate is
・ Electrostatic force, van der Waals force, liquid bridging force, and surface roughness of inclined plate were considered.
[0014]
Whatever the cause, the microspheres are stuck to the inclined plate or adsorbed to each other, thereby slowing the flow of the spheres. Therefore, in the present invention, the attached microspheres are separated by applying vibration to the inclined plate.
[0015]
If the tilt angle of the tilt plate is too small, the microspheres will not flow smoothly even if it is vibrated. On the other hand, if the tilt angle is too large, there will be no clear difference between the rolling direction and the flying distance between the non-defective product and the defective ball, which will hinder the selection. coming out.
[0016]
In addition, when the frequency is too low or too high, the effect of applying the vibration is not sufficiently extracted.
[0017]
For the inclination angle of the inclined plate of 3 to 10 degrees and the frequency of 300 Hz to 500 Hz, the best place was selected through experiments.
[0018]
Next, the upper surface of the inclined plate seems to have a good mirror surface considering the rolling resistance of the sphere. However, in practice, the surface on which innumerable fine streaks extending in the vertical direction (front-rear direction of the inclined plate) are observed is better than the mirror surface. By forming this surface, a sphere having a diameter of 300 μm or less is selected. Became possible. The roughness of the upper surface should be in the range of 0.1 mm to 0.4 mm with irregularities due to streak.
[0019]
Note that the effect of static electricity can be eliminated by forming the inclined plate with the same material as the sphere to be selected, or providing the conductive film for grounding on the upper surface of the inclined plate.
[0020]
Further, when an electrostrictive element is used as a vibration source, the influence of electromagnetic force does not appear.
[0021]
Further, the one provided with the longitudinal groove, the deformed ball collecting portion, and the sorting plate is also sorted by a flight distance difference, and the sorting reliability is further increased.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show an embodiment of the present invention. This sorting apparatus includes a flat inclined plate 1 having an inclination angle θ set to 3 ° to 10 °, an excitation source 2 that vibrates the inclined plate, a drive control unit 3 for the excitation source, and a tip of the inclined plate. A holder 4 for supporting the distance, a longitudinal groove 5 (see FIG. 2) provided on the top surface of the tip of the inclined plate 1 for performing the distance difference selection, an opening 7 for dropping the deformed sphere onto the deformed sphere collecting section 6, and a true sphere. It consists of a sorting plate 9 that leads to the true sphere collection unit 8.
[0023]
The inclined plate 1 is preferably made of the same material as the sphere to be selected. The upper surface of the inclined plate 1 is a surface on which countless fine streaks 10 are observed. The streak 10 is unevenness of about 0.1 mm to 0.4 mm, and extends in the front-rear direction of the inclined plate 1 with a minute interval.
[0024]
As the vibration source 2, an electrostrictive element that has no magnetic influence is used. A typical electrostrictive element is a PZT actuator (commercial name, composition of lead-zirconate-titanate), which was used.
[0025]
The drive controller 3 provided the pulse signal output from the sequencer to the excitation source 2 and was not as effective as expected. Therefore, the drive controller 3 provided the signal from the personal computer 3a via the amplifier 3b.
[0026]
The longitudinal grooves 5 are provided at a pitch at which the spheres always enter and flow into the grooves. Further, in order to prevent the sphere that has entered the vertical groove 5 from jumping out of the groove by vibration, the tip of the inclined plate 1 is held by the holder 4 to suppress vibration (amplitude).
[0027]
The opening 7 is provided forward along the tip of the inclined plate 1. Further, the separation plate 9 is provided at a drop point (in front of the opening 7) of a true sphere (good product) that is accelerated and rolls down.
[0028]
The sorting apparatus configured as described above supplies the microsphere B to be sorted, and vibrates the inclined plate 1 by the vibration source 2. Alternatively, a sphere is supplied on the vibrating inclined plate. For vibration, sine wave, triangle wave, rectangular wave, sawtooth wave, white noise, and pink noise were tested, but sine wave was most effective. Further, when the inclination angle of the inclined plate 1 is changed from 1 degree to 10 degrees in increments of 1 degree, and the frequency is 0, 100 Hz, 200 Hz, 250 Hz, 300 Hz, 350 Hz, 400 Hz, 450 Hz, 500 Hz, 600 Hz for each angle. As a result, the flow of the sphere was particularly smooth when the inclination angle was 3 to 10 degrees and the vibration frequency was 350 Hz to 500 Hz (in particular, 350 Hz).
[0029]
This vibration and the fine irregularities (streaks) on the upper surface of the inclined plate effectively act to prevent the adhesion of the microsphere to the inclined plate, which has been a problem in the selection of microspheres of 300 μm or less. Adsorption of spheres is also prevented, and the true sphere and some deformed spheres (a twin sphere with no circumference difference and no inclination of the posture) rolls down straight. On the other hand, the parent-child sphere rolls diagonally and is removed from the true sphere group.
[0030]
Next, the sphere B rolled down straight enters the longitudinal groove 5. Even if the good sphere enters the groove, it is accelerated and continues to roll, jumps out from the tip of the inclined plate 1, falls on the sorting plate 9, and is guided to the true sphere collection unit 8. On the other hand, the twin sphere is restrained by the groove 5 and hardly rolls, decelerates and falls from the opening 7 to the deformed sphere collecting part 6.
[0031]
As described above, in the illustrated apparatus, the distance selection is performed following the inclination selection based on the difference in the rolling direction, and the deformed sphere is removed with high probability.
[0032]
The background of the development of the present invention will be described below.
The causes of adhesion and mutual adsorption of the microspheres on the inclined plate were estimated as four factors: electrostatic force, van der Waals force, liquid bridging force, and surface roughness of the inclined plate, and their influence was investigated. First, when a glass plate having a good surface roughness was used as the inclined plate, the flow of the spheres was slightly improved but not sufficient.
[0033]
Next, when a conductive film (ITO film) was deposited on the glass surface in the suspicion of static electricity, it was better than the glass surface without the ITO film, but when it became a sphere with a diameter of 0.2 mm, it adhered completely. In addition, the sphere having a diameter of 80 μm did not fall on the glass surface on which the ITO film was formed even if the glass plate was turned over.
[0034]
From this phenomenon, I thought that it might be related to minute static electricity that could not be grounded even with an ITO film, and I tried using various commercially available static eliminators, but there was no effect.
[0035]
“There are two metals A and B of work relationship W1 and W2 (W1 <W2) in the item of contact charging in the document“ Basics of static electricity and antistatic technology written by Yuji Murata ”. Electrons move from the small metal A to the large metal B. The movement of the electrons occurs when the surfaces of the two metals are very close together. This is a phenomenon called the tunnel effect. It was considered that the 80 μm sphere did not fall even when the glass plate was turned upside down as a result of the potential difference occurring on the contact surface due to contact charging, and + − attracting each other.
[0036]
In contact charging, the potential of the contact surface cancels out and becomes zero, so that it is considered impossible to remove static electricity with an electrostatic remover that sends in ions. Moreover, this charging is such that +-is attracted to each other, and even if it is a conductor, electricity is not grounded.
[0037]
Further, when the diameter of the sphere becomes small and the electrostatic force becomes larger than the force of rolling on the plane, it not only rolls but also does not fall even if the glass plate is turned upside down. This is because the mass decreases in proportion to the cube of the dimension (radius r) (volume V = 4 / 3πr ³ ), whereas the surface area decreases in proportion to the square (surface area S = 4πr ² ). This is probably because the influence of the surface is relatively increased. When the numerical values when the radius of the sphere becomes 1/10 are compared, the volume becomes 1/1000 while the surface area becomes 1/100.
[0038]
For these reasons, it was thought that the adhesion of the microspheres to the inclined plate was due to static electricity, but after sorting the defects, twin balls were found in the non-defective balls of the same material and size in the tray.
[0039]
If you look closely at this sphere, it can be easily separated by simply pressing it with your finger. When a good ball is placed in a tray and rolled, a twin ball is always found. When all the balls are separated and the tray is shaken, a twin ball appears again. From the description of the previous document, it may be considered that contact charging does not occur between spheres of the same material and substantially the same volume, and it is necessary to consider that there is another attractive force.
[0040]
If the force is not surface roughness or electrostatic force, van der Waals force and liquid bridging force are mentioned.
[0041]
A test was conducted to determine whether an 80 [mu] m copper ball can be subjected to tilt sorting using a copper plate and a stainless steel plate. Both the copper plate and the stainless steel plate were grounded so as to have an inclination angle of 7 degrees and not to have a potential, and an 80 μm diameter copper ball contained in a grounded box was allowed to flow on these plates. In parallel with this, copper balls were flowed under the same conditions on a glass plate provided with an ITO film and a normal soda glass plate without an ITO film. As a result, the flow with a copper plate of the same material was very good. Contact charging does not occur because the sphere and the inclined plate are made of the same material. Moreover, since the test was performed in an atmosphere at an air temperature of 25 ° C. and a humidity of 30%, it may be considered that the influence of the liquid crosslinking force is small. Nevertheless, adhesion of spheres to the copper plate and adsorption of spheres occurred. From this result, it was judged that there was an influence of van der Waals force in addition to static electricity.
[0042]
In addition, when all the spheres are affected by van der Waals forces, a large number of spheres should adsorb each other, but it seems that a special situation is involved because of the fact that several percent adsorb. .
[0043]
Therefore, another experiment was tried. The flow of 80 μm copper spheres was compared using a copper plate with a mirrored surface by lapping the surface and a copper plate with numerous fine irregularities (streaks) on the surface. The copper plate is cleaned, wiped and dried under the same conditions. In this test, it was confirmed that the latter copper plate had better sphere flow and the surface roughness also affected. If you think that a few percent of twin spheres are due to the fact that the surface with good surface roughness approached by chance, the congruity goes.
[0044]
When the two particles are brought closer to each other by van der Waals force, an elastic repulsion force due to deformation acts, and the balance between the two particles causes the particle to settle to the most stable position (position where the potential energy is minimum). This position is such that the interparticle distance z = zo in FIG. 6 is about 0.4 nm in the air.
[0045]
As shown in FIG. 6, the particles are divided into a solid core portion C and an uneven shell portion S and integrated, and the adhesion force Fvb of the rough particles to the mating surface is obtained.
[0046]
Fvb = {z / (z + b)} ² Fv
Here, b is the surface roughness, and Fv is the van der Waals force at a distance z.
[0047]
Depending on the surface roughness, it can be considered that the distance between the two spheres is far from z to zb, and the adhesion force is weakened accordingly. For example, when particles having a diameter of 10 μm adhere to each other at z = 0.4 nm in FIG. 6, if the surface roughness is 0.1 μm, the adhesion is reduced to about 1 / 60,000. As can be seen from the above equation, the rate of decrease is determined only by the ratio of the surface roughness to the distance between the two. Regardless of the particle size, if the surface roughness is 1 μm, the adhesion is further reduced by a factor of 100, which is 6 million minutes 1
[0048]
When the diameter of the sphere is around 300 μm or less, the mass proportional to the cube of the radius becomes very small, so that the influence of external force on the sphere increases. Therefore, in addition to providing vibration, the use of the top surface of the inclined plate as a surface on which fine streaks are observed greatly helps to improve the flow of the microspheres.
[0049]
【The invention's effect】
As described above, the sorting apparatus according to the present invention vibrates the inclined plate to give a separation force to the spheres sucked and adhered to the inclined plates and the spheres sucked and attached to each other, and appropriately roughens the upper surface of the inclined plate. Since the adhesion force of the microspheres to the inclined plate itself is weakened, it becomes possible to select microspheres having a diameter of 300 μm or less, which brings a great industrial benefit.
[Brief description of the drawings]
FIG. 1 is a side view showing an outline of an apparatus according to an embodiment. FIG. 2 is a plan view of an essential part of the apparatus. FIG. 3 is an enlarged front view of an inclined plate. FIG. 5 is a diagram showing the principle of the gradient selection method. FIG. 6 is an explanatory diagram of the relationship between the surface roughness of van der Waals force.
DESCRIPTION OF SYMBOLS 1 Inclined plate 2 Excitation source 3 Drive control part 3a Personal computer 3b Amplifier 4 Holder 5 Longitudinal groove 6 Deformation ball | bowl collection | recovery part 7 Opening 8 True sphere collection | recovery part 9 Sorting plate 10 Streak B Microsphere

Claims (1)

A flat plate that rolls with a microsphere having a diameter of 300 μm or less, an inclined plate provided with a conductive film to be grounded on the upper surface, and a vibration source that vibrates the inclined plate in the thickness direction. The angle is set to 3 to 10 degrees, the frequency is set to 300 Hz to 500 Hz, and the upper surface of the inclined plate is formed into a surface on which innumerable fine streaks extending in the vertical direction are observed, and a minute amount is formed on the tip side of the inclined plate. A vertical groove is provided to allow the sphere to enter and give directionality to the movement of the sphere, and further, a deformed sphere collecting part for dropping the slidable deformed sphere restrained by the vertical groove from the tip of the inclined plate, and the inside of the vertical groove An apparatus for sorting microspheres, which is configured by adding a separation plate that guides a true sphere that rolls down and falls in front of the deformed sphere collection unit to the true sphere collection unit .

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