JP4577624B2

JP4577624B2 - Method for producing spherical particles

Info

Publication number: JP4577624B2
Application number: JP2007232879A
Authority: JP
Inventors: 拓志上田; 元通伊藤; 光司佐藤; 武平林; 健久保井
Original assignee: Hitachi Metals Ltd
Current assignee: Hitachi Metals Ltd
Priority date: 2007-09-07
Filing date: 2007-09-07
Publication date: 2010-11-10
Anticipated expiration: 2022-03-29
Also published as: JP2007330968A

Description

本発明は、溶融体から球状粒子を製造する方法に関する。 The present invention relates to a method for producing spherical particles from a melt.

金属、樹脂、或いはガラスなどの材料からなる球状の粒子は、溶融体を出発原料として種々の方法で製造されており、例えば特開２０００−１４４２１６号公報には、所定の微小粒径を持ち且つ所定の真球度を持つ球状粒子の製造方法としてＢＧＡ用半田ボールの製造方法が開示されている。これは、滴下ノズルを有する収容容器内の溶融金属に振動を与えながら、該滴下ノズルから溶融金属を冷却液面に滴下させ、該冷媒により冷却して球状金属粒子を製造する方法において、冷媒として球状金属粒子を酸化させず、後処理で除去・分離が容易な潤滑油を用い、また該滴下ノズルから該冷媒液面までの距離を特定の範囲の長さにするとともに、球状金属粒子を洗浄して潤滑剤を除去し、粒径に基づいて分級し、さらに真球度に基づいて選別するものである。
特開２０００−１４４２１６号公報 Spherical particles made of a material such as metal, resin, or glass are produced by various methods using a melt as a starting material. For example, JP 2000-144216 A has a predetermined fine particle size and As a method for producing spherical particles having a predetermined sphericity, a method for producing a solder ball for BGA is disclosed. This is because, in the method of manufacturing spherical metal particles by dropping molten metal from the dropping nozzle onto the cooling liquid surface while cooling the molten metal in the container having the dropping nozzle and cooling with the refrigerant, Lubricating oil that does not oxidize spherical metal particles and can be easily removed and separated by post-processing is used, and the distance from the dripping nozzle to the coolant liquid surface is set to a specific range, and the spherical metal particles are washed. Then, the lubricant is removed, classified based on the particle diameter, and further selected based on the sphericity.
JP 2000-144216 A

上記公報には、ノズルの径及び振動数を調整することにより、潤滑油中に平均値として所望粒径の球状金属粒子を得ることができる、と記載されている。しかし、製造ロット毎に、溶融金属の温度、材質、量など粒径に影響する諸条件は変動するため、これに対応してノズル径及び振動数を調整しなければならないが、具体的な調整方法は開示されていない。経験則をもとに調整するにしても、粒子製造工程後の潤滑油除去、乾燥後の分級工程又は粒径測定工程を経て、はじめて球状粒子が所望の粒径であるか否かが確認されるため、規格外品を大量に製造してしまう恐れがある。また、たとえ平均値としては所望粒径であっても、所定寸法範囲外品が大量に含まれてしまい、歩留まりが低下する恐れもある。即ち、この粒子製造方法はオープンループの製造方式であり、粒子製造中の条件変動には対応できないため、信頼性及び安定性に問題がある。また、潤滑油中から球状金属粒子を取出し、潤滑油を除去する工程が必要であり、製造時間が長くなるだけでなく装置的にも複雑となる。従って、本発明は、溶融体を球状粒子化する工程で、所定粒径のそろった球状粒子を信頼性高く安定して製造することができる球状粒子の製造方法を提供することを目的としている。 The above publication describes that spherical metal particles having a desired particle diameter can be obtained as an average value in the lubricating oil by adjusting the nozzle diameter and frequency. However, the conditions that affect the particle size, such as the temperature, material, and quantity of the molten metal, vary from production lot to production lot, so the nozzle diameter and frequency must be adjusted accordingly. The method is not disclosed. Even if it is adjusted based on empirical rules, it is only confirmed whether the spherical particles have the desired particle size after the removal of the lubricating oil after the particle production process, the classification process after drying, or the particle size measurement process. Therefore, there is a risk of manufacturing a large amount of non-standard products. Moreover, even if the average particle size is a desired particle size, a large amount of products outside the predetermined dimension range are included, and the yield may be reduced. That is, this particle manufacturing method is an open-loop manufacturing method and cannot cope with a change in conditions during particle manufacturing, and thus there is a problem in reliability and stability. Further, a step of taking out the spherical metal particles from the lubricating oil and removing the lubricating oil is necessary, which not only increases the manufacturing time but also complicates the apparatus. Accordingly, an object of the present invention is to provide a method for producing spherical particles, which can reliably and stably produce spherical particles having a predetermined particle size in the step of making the melt into spherical particles.

本発明は、容器内の細孔から溶融体を注出して球状粒子を製造する方法において、所定直径の粒子を製造するための実製造工程と、実製造工程に先立って行うサンプル製造工程とを有し、サンプル製造工程では、オリフィスから滴下された粒子直径と粒子間距離を測定し、これらのデータを粒子直径と粒子間距離との相関を表した所定式に代入して所定式中の定数を規定するとともに、測定された粒子直径をもとに狙い値に近い直径の粒子が得られる操作量を求め実製造工程における操作機器の初期操作量とし、実製造工程では、操作機器を前記初期操作量で作動し、滴下中の粒子間距離をインラインで測定し、測定された粒子間距離を定数が規定された前記所定式に代入して滴下中の粒子直径を算出し、算出された粒子直径に基づいて操作機器を制御することを特徴としている。また、本発明は、容器内の細孔から溶融体を注出して球状粒子を製造する方法において、所定直径の粒子を製造するための実製造工程と、実製造工程に先立って行うサンプル製造工程とを有し、サンプル製造工程では、オリフィスから滴下された粒子直径と粒子間距離を測定し、これらのデータを粒子直径と粒子間距離との相関を表した所定式に代入して所定式中の定数を規定し、定数が規定された前記所定式に粒子直径の狙い値を代入して粒子間基準距離を求めるとともに、測定された粒子直径をもとに狙い値に近い直径の粒子が得られる操作量を求め実製造工程における操作機器の初期操作量とし、実製造工程では、操作機器を前記初期操作量で作動し、滴下中の粒子間距離をインラインで測定し、測定された粒子間距離と前記粒子間基準距離とを比較して操作機器を制御することを特徴としている。また、本発明は、容器内の細孔から溶融体を注出して球状粒子を製造する方法において、所定直径の粒子を製造するための実製造工程と、実製造工程に先立って行うサンプル製造工程とを有し、サンプル製造工程では、オリフィスから滴下された粒子直径と粒子間距離を測定し、これらのデータを粒子直径と粒子間距離との相関を表した所定式に代入して所定式中の定数を規定し、定数が規定された前記所定式に粒子直径の狙い値を代入して粒子間基準距離を求めるとともに、実製造工程における粒子間距離をその求めた粒子間基準距離にするための操作機器の操作量を所定の調整ルールにより決定することを特徴としている。前記所定式としては、D＝αλ^１／３で表される（ここで、Ｄは粒子直径、λは粒子関距離、αは定数である。）を用いることが望ましい。前記発明における粒子間距離の測定は、滴下中の複数の粒子を撮像し、粒子間の距離を画像処理で算出するようにすることが好ましい。また、粒子間距離の測定に当たって、作動距離が滴下ラインと同一寸法となるようにセットした既知寸法のマーキングを撮像して、倍率調整後の画素サイズを自動校正するようにするとよい。 The present invention relates to a method for producing spherical particles by pouring a melt from pores in a container, and an actual production process for producing particles having a predetermined diameter and a sample production process performed prior to the actual production process. In the sample manufacturing process, the particle diameter dropped from the orifice and the distance between the particles are measured, and these data are substituted into a predetermined expression representing the correlation between the particle diameter and the distance between the particles, and the constants in the predetermined expression In addition, the operation amount for obtaining particles having a diameter close to the target value based on the measured particle diameter is obtained and used as the initial operation amount of the operation device in the actual manufacturing process. Operates with a manipulated variable, measures the inter-particle distance during dropping in-line, substitutes the measured inter-particle distance into the predetermined formula for which a constant is defined, calculates the particle diameter during dropping, and calculates the calculated particle Operation based on diameter It is characterized by controlling the vessel. The present invention also relates to an actual manufacturing process for manufacturing particles having a predetermined diameter in a method for producing spherical particles by pouring a melt from pores in a container, and a sample manufacturing process performed prior to the actual manufacturing process. In the sample manufacturing process, the particle diameter dropped from the orifice and the distance between the particles are measured, and these data are substituted into a predetermined expression representing the correlation between the particle diameter and the distance between the particles. And substituting the target value of the particle diameter into the predetermined formula for which the constant is defined to obtain the inter-particle reference distance, and obtaining particles having a diameter close to the target value based on the measured particle diameter. The operation amount is determined as the initial operation amount of the operation device in the actual manufacturing process. In the actual manufacturing process, the operation device is operated at the initial operation amount, and the interparticle distance during dropping is measured in-line. Distance and interparticle base It is characterized by controlling the operating device by comparing the distance. The present invention also relates to an actual manufacturing process for manufacturing particles having a predetermined diameter in a method for producing spherical particles by pouring a melt from pores in a container, and a sample manufacturing process performed prior to the actual manufacturing process. In the sample manufacturing process, the particle diameter dropped from the orifice and the distance between the particles are measured, and these data are substituted into a predetermined expression representing the correlation between the particle diameter and the distance between the particles. In order to obtain the inter-particle reference distance by substituting the target value of the particle diameter into the predetermined formula in which the constant is defined, and to make the inter-particle distance in the actual manufacturing process the obtained inter-particle reference distance The operation amount of the operating device is determined by a predetermined adjustment rule. As the predetermined formula, it is desirable to use D = αλ ^1/3 (where D is a particle diameter, λ is a particle distance, and α is a constant). In the measurement of the interparticle distance in the invention, it is preferable that a plurality of particles being dropped are imaged and the distance between the particles is calculated by image processing. In measuring the interparticle distance, it is preferable to image a marking having a known dimension set so that the working distance is the same as that of the dropping line, and automatically calibrate the pixel size after the magnification adjustment.

本発明によれば、半田ボールに限らず、実製造開始時から所定の直径の球状粒子を製造できるので、大量に規格外品を製造してしまうことがない。また、製造中の球状粒子の直径を精度よく監視し、これをもとに製造条件を調整することができるので、所望の粒径範囲の球状粒子を信頼性高く製造することができる。また、粒径のばらつきが大きく、大量に規格外品を含むような球状粒子を後工程に流すことがないので、生産効率を高めることができる。 According to the present invention, not only solder balls but also spherical particles having a predetermined diameter can be produced from the start of actual production, so that non-standard products are not produced in large quantities. Further, since the diameter of the spherical particles being manufactured can be accurately monitored and the manufacturing conditions can be adjusted based on this, the spherical particles having a desired particle size range can be manufactured with high reliability. Moreover, since the dispersion | variation in a particle size is large and a spherical particle which contains a nonstandard product in large quantities is not sent to a post process, production efficiency can be improved.

球状粒子は種々の製品があり、その性状及び材質によって種々の製造方法が採られるが、本発明は、容器内の溶融体を細孔から注出・滴下して球状化させる製品に適用できるものである。なお、溶融体は、自重で注出される場合だけでなく、容器内に圧力をかけて注出される場合も多く、注出される方向も必ずしも鉛直方法とは限らないが、以下、半田ボール（以下単にボールと言う）を対象とし、重力方向に注出される例で説明する。なお、本発明でいう製造方法は、容器内の溶融体を細孔から注出・滴下して球状化させる工程に係わるものであり、球状粒子形成後の分級、検査等の後工程を規定するものではない。 There are various types of spherical particles, and various manufacturing methods are adopted depending on their properties and materials. The present invention can be applied to products in which the molten material in a container is spheroidized by pouring and dropping from the pores. It is. The melt is not only poured out by its own weight, but is often poured out by applying pressure into the container, and the direction in which the melt is poured is not necessarily a vertical method. This will be described with an example in which it is poured out in the direction of gravity. The production method referred to in the present invention relates to the step of spheroidizing the molten material in the container by pouring and dripping from the pores, and defines the subsequent steps such as classification and inspection after the formation of spherical particles. It is not a thing.

図１は本発明に係わるボール製造装置の一例を示す概略図である。溶融金属（以下、溶湯と称す）１は、細孔３を有した容器２に、温度調節手段（図示せず）で所定の温度に調整されて収容されており、容器２は配管を介してガス調圧手段と接続され、内部を所定圧力に調整することができる。細孔３は、所望のボール直径に合せて、所定の穴径を有した形状に形成されている。容器２内の細孔３の上方には加振ロッド４が配設され、例えばピエゾ素子のような振動子５により、所定の振動数と振幅を溶湯１に付与することができる。細孔３の下方で、細孔から滴下してほぼ球状に分離されたボール６の落下ラインの左右には、ボール６を撮像するためのカメラ７とストロボランプ８が配設されている。前記ガス調圧手段、振動子５、カメラ７及びストロボランプ８は、制御装置９に電気的に接続されている。制御装置９にはパソコンなどの演算・記憶手段や画像処理手段が備えられている。 FIG. 1 is a schematic view showing an example of a ball manufacturing apparatus according to the present invention. Molten metal (hereinafter referred to as molten metal) 1 is accommodated in a container 2 having pores 3 at a predetermined temperature adjusted by a temperature adjusting means (not shown). Connected to the gas pressure adjusting means, the inside can be adjusted to a predetermined pressure. The pores 3 are formed in a shape having a predetermined hole diameter in accordance with a desired ball diameter. An excitation rod 4 is disposed above the pores 3 in the container 2, and a predetermined frequency and amplitude can be imparted to the molten metal 1 by a vibrator 5 such as a piezoelectric element. A camera 7 and a strobe lamp 8 for taking an image of the ball 6 are disposed on the left and right sides of the drop line of the ball 6 dropped from the pore and separated into a substantially spherical shape below the pore 3. The gas pressure adjusting means, vibrator 5, camera 7 and strobe lamp 8 are electrically connected to a control device 9. The control device 9 is provided with calculation / storage means such as a personal computer and image processing means.

ストロボランプ８は振動子５の周波数に同期して発光し、カメラ７は略球状に形成された複数のボール６を静止画像として撮像することができる。カメラ７には、視野内に少なくとも２個のボール６が撮像されるような倍率の光学系が装着される。撮像された静止画像は制御装置９に送られ、画像処理等で後述する所定の処理が行われる。なお、静止画像を得るためには、ストロボランプ８に代え、連続照明光発光手段とシャッターを用い、シャッターを振動子５の周波数に同期させて開閉するようにしてもよい。 The strobe lamp 8 emits light in synchronization with the frequency of the vibrator 5, and the camera 7 can capture a plurality of balls 6 formed in a substantially spherical shape as still images. The camera 7 is equipped with an optical system with such a magnification that at least two balls 6 are imaged in the field of view. The captured still image is sent to the control device 9, and predetermined processing described later is performed by image processing or the like. In order to obtain a still image, continuous illumination light emitting means and a shutter may be used in place of the strobe lamp 8, and the shutter may be opened and closed in synchronization with the frequency of the vibrator 5.

次にボールの製造方法について説明する。ボール６の製造は、溶湯１が保持された容器２内にガス調圧手段で所定圧力を付与するとともに、溶湯１に浸漬した加振ロッド４に振動子５から高周波振動を伝え、溶湯１を所定速度で細孔３から注出させることにより行う。細孔３を通過した直後の溶湯１は柱状であるが、直ぐに付加された振動により分断されて滴下し、冷却されて球状となる。溶湯温度、容器内圧力、振動数などを制御する温度調節手段、ガス調圧手段、振動子の操作機器は、ボールの材質や量及び所望の直径に合せ、かつ形成された細孔３の性状等を考慮した経験的に得られた所定の操作量に設定される。この操作量によって、細孔３を通過した液柱の断面積、注出速度及び分断タイミングが決まり、ボール６の直径が規定される。 Next, a ball manufacturing method will be described. The ball 6 is manufactured by applying a predetermined pressure to the container 2 in which the molten metal 1 is held by gas pressure adjusting means, and transmitting high-frequency vibration from the vibrator 5 to the vibration rod 4 immersed in the molten metal 1. It is carried out by pouring from the pores 3 at a predetermined speed. The molten metal 1 immediately after passing through the pores 3 has a columnar shape, but is divided and dropped by the vibration added immediately and cooled to become spherical. The temperature adjusting means for controlling the molten metal temperature, the pressure in the container, the vibration frequency, etc., the gas pressure adjusting means, and the vibrator operating device are adapted to the material and amount of the ball and the desired diameter, and the properties of the formed pores 3 It is set to a predetermined operation amount obtained empirically considering the above. The operation amount determines the cross-sectional area of the liquid column that has passed through the pores 3, the pouring speed, and the dividing timing, and the diameter of the ball 6 is defined.

上述したように、各操作機器の基本的な操作量は経験的に求められているが、溶湯温度や、細孔の形状や面粗さ等のばらつきにより溶湯が細孔を通過する時の抵抗や通過後の温度などを常に同一とすることは難しく、操作量が同じでも形成されるボールの直径が常に狙い値どおりになるとは限らない。これは、製造ロットが異なると特に著しくなる。また、同じ製造ロットであっても、製造中の時間経過に伴い、溶湯の温度変化による粘度や比重などの物性値変動や、細孔穴部への溶湯の付着や表面の損傷など細孔性状変動や、溶湯量の減少などに伴う押出し力の変動などにより液柱の断面積や速度などが変動すると、分断されたボールの容量が変動しボール直径が変動してくる。従って、所定寸法範囲のボールを安定して得るためには、ボール製造中にインラインでボール直径に関する情報を求め、この情報をもとにインラインで制御可能なガス調圧手段、振動子などの操作機器を適宜制御することが好ましく、さらに製造ロットに係わらず製造開始時から狙い値どおりのボールが得られるように操作機器の初期操作量を設定することが望ましい。 As described above, the basic operation amount of each operating device is empirically determined, but the resistance when the molten metal passes through the pores due to variations in the molten metal temperature, pore shape, surface roughness, etc. It is difficult to always keep the same temperature after passing, and the diameter of the formed ball is not always the target value even if the operation amount is the same. This is particularly noticeable with different production lots. In addition, even with the same production lot, over time during production, changes in physical properties such as viscosity and specific gravity due to temperature changes of the molten metal, and fluctuations in pore properties such as adhesion of molten metal to the pore holes and surface damage If the cross-sectional area or speed of the liquid column fluctuates due to fluctuations in the extrusion force accompanying the decrease in the molten metal amount, etc., the volume of the divided ball fluctuates and the ball diameter fluctuates. Therefore, in order to stably obtain a ball within a predetermined size range, information on the ball diameter is obtained in-line during ball production, and operations such as gas pressure control means and vibrators that can be controlled in-line based on this information are obtained. It is preferable to control the device as appropriate, and it is desirable to set the initial operation amount of the operating device so that a ball according to the target value can be obtained from the start of manufacturing regardless of the manufacturing lot.

そのために、実際の製造に入る前にまず少量のボールを製造するサンプル製造を行う。サンプル製造は、対象のボールに対して経験的に得られている基本的な操作量をもとにし、圧力や振動数などの条件を変えたｎ種類の組み合わせで行い、各サンプル製造時のボール直径を測定する。通常、サンプル製造条件に応じて異なった直径のボールが得られるため、狙い値に近い直径のボールが得られた時の条件を抽出し、それを実製造に用いるという方法を採用することが考えられる。しかし、そのためにはｎ数を大きくする必要があり、その分生産効率が低下するし、また必ずしも狙い値に近い直径のボールが得られるとは限らない。このため、少ないサンプル製造（ｎ＝１〜４程度）で操作量を決定できるような方法を採用することが望まれる。初期操作量を決定するだけであれば、前記サンプル製造で得られたボール直径が狙い値に近いものがなくても、多数の製造実績をもとにした経験則などから適宜決めるようにすることもできるが、実際に形成されるボール直径を確認したり、製造中の操作量を見ながら操作機器を制御するためには、ボール直径情報を有する制御量がインラインで求められなければならない。 Therefore, before starting actual production, sample production for producing a small amount of balls is first performed. Samples are manufactured in n combinations with different conditions such as pressure and frequency, based on the basic operation amount obtained empirically for the target ball. Measure the diameter. Usually, balls with different diameters are obtained according to sample manufacturing conditions. Therefore, it is considered to adopt a method of extracting the conditions when a ball with a diameter close to the target value is obtained and using it for actual manufacturing. It is done. However, for that purpose, it is necessary to increase the number of n, and accordingly, the production efficiency is lowered, and a ball having a diameter close to the target value is not always obtained. For this reason, it is desirable to employ a method that can determine the manipulated variable with a small sample production (n = 1 to 4). If only the initial manipulated variable is to be determined, even if the ball diameter obtained in the sample manufacturing is not close to the target value, it should be determined as appropriate based on empirical rules based on numerous manufacturing results. However, in order to check the ball diameter actually formed or to control the operating device while watching the operation amount during manufacture, the control amount having the ball diameter information must be obtained in-line.

ボール直径に係わる制御量としては、ボール直径そのものを用いてもよいが、本発明者らはボール間距離を用いた方が好ましいことを見出し、制御量としてボール間距離を用いることにした。即ち、本発明者らは、下記で示される理論式１より、ボール直径Ｄと滴下してほぼ球状となった時のボール間距離λとに相関があることに着目し、後述するようにボール間距離の変動の方が、ボール直径の変動より感度高く表れること、かつ正確に球状に形成されていなくても安定して計測できることを実験により確認した。式１は、オリフィスから出た単位時間当たりの液中の重量とこれから分離して球状化した全ボールの重量は等しい、ということから導かれたものである。なお、インラインでボール間距離を測定する方法については後述する。
Ｄ＝αλ^１／３ …（１）
定数αは、サンプル製造時に測定したボール直径とボール間距離を、式１のＤ、λに代入することで算出できる。実際には、ボール直径やボール間距離の測定誤差、溶湯温度の変動などでばらついて異なる値となることがあるため、例えば平均値を計算して用いるとよい。 Although the ball diameter itself may be used as the control amount related to the ball diameter, the present inventors have found that it is preferable to use the inter-ball distance, and decided to use the inter-ball distance as the control amount. That is, the present inventors pay attention to the fact that there is a correlation between the ball diameter D and the inter-ball distance λ when dropped into a substantially spherical shape from the theoretical formula 1 shown below. It was confirmed by experiments that the variation in the inter-distance appears more sensitively than the variation in the ball diameter, and that it can be measured stably even if it is not accurately spherical. Equation 1 is derived from the fact that the weight of the liquid per unit time that exits the orifice is equal to the weight of all the balls that are separated and spheroidized. A method for measuring the distance between balls in-line will be described later.
D = αλ ^1/3 (1)
The constant α can be calculated by substituting the ball diameter and inter-ball distance measured at the time of sample manufacture into D and λ of Equation 1. Actually, the value may vary depending on the measurement error of the ball diameter and the distance between balls, the fluctuation of the molten metal temperature, and the like. For example, an average value may be calculated and used.

その製造ロット用の定数αが規定されると、製造するボール直径の狙い値を式１のＤに代入することで、制御量としてのボール間距離の基準値λｓを求めることができる。製造開始時にボール間距離を基準値λｓにするための操作機器の初期操作量は、製造時に収集したデータをもとにした調整ルールを決めておき、これをもとに決定すればよい。なお、サンプル製造において、ボール直径Ｄが狙い値にほぼ一致するような場合、ボール間距離の基準値λｓはその時の測定値を用い、操作機器の初期操作量もその時のものを用いるようにしてもよい。 When the constant α for the production lot is specified, the reference value λs of the distance between the balls as the control amount can be obtained by substituting the target value of the diameter of the ball to be produced into D of Equation 1. The initial operation amount of the operating device for setting the ball-to-ball distance to the reference value λs at the start of manufacturing may be determined based on an adjustment rule based on data collected during manufacturing. When manufacturing the sample, when the ball diameter D is substantially equal to the target value, the reference value λs of the distance between the balls is the measured value at that time, and the initial operation amount of the operating device is also used at that time. Also good.

ボール間距離λは、後述するようにインラインで測定するため、製造中に基準値λｓと比較することで、製造されているボールの直径に係わる情報をモニター表示したり、操作機器を制御したりすることができる。即ち、製造開始直後においては、ボールが所望の狙い値通りにあるか否かをモニタリングし、製造されたボール直径が狙い値から所定範囲外れている場合は、アラームを発して製造を中止するようにするとよい。また製造中においては、ボール直径を所定寸法範囲内に維持するように制御を行うようにするとよい。制御は、手動でも自動でもいずれで行ってもよい。手動で制御する場合は、測定されるボール間距離λをもとに、例えば前記式１からボール直径又はボール直径の変動値を算出し、ボールの寸法履歴などが視覚的、感覚的にわかるようにモニタ表示すると、操作者は経験や或は予め決めたマニュアルなどをもとに制御すべき操作機器に対し適切な微調整を行うことができる。また、自動で制御する場合は、例えば制御量の偏差と各操作機器の操作方法の関係を制御ルールとして設定しておけば、公知の方法でフィードバック制御をすることができる。 Since the inter-ball distance λ is measured in-line as will be described later, information related to the diameter of the ball being manufactured can be displayed on the monitor or the operation device can be controlled by comparing it with the reference value λs during the manufacturing. can do. That is, immediately after the start of production, it is monitored whether or not the ball is at a desired target value. If the manufactured ball diameter is out of the predetermined range from the target value, an alarm is issued to stop the production. It is good to. During manufacture, control may be performed so as to maintain the ball diameter within a predetermined size range. Control may be performed either manually or automatically. In the case of manual control, based on the measured distance between balls λ, for example, the ball diameter or the fluctuation value of the ball diameter is calculated from the above equation 1, so that the ball size history etc. can be visually and intuitively understood. When the monitor is displayed on the monitor, the operator can make an appropriate fine adjustment to the operating device to be controlled based on experience or a predetermined manual. In the case of automatic control, for example, if the relationship between the control amount deviation and the operation method of each operation device is set as a control rule, feedback control can be performed by a known method.

ここで、ボール直径の変動とボール間距離の変動の関係について説明する。図２は、直径の異なる４種類のボールを製造した時の、ボール直径変動とボール間の距離変動との関係の一例を示したものである。例えば、直径３００μｍのボールの場合、直径が１μｍ大きくなる毎にボール間の距離が約９μｍ長くなっており、また、直径６００μｍのボールの場合、直径が１μｍ大きくなる毎にボール間の距離が約４μｍ長くなっており、直径の小さなボールほど、直径の変動がボール間の距離変動として大きく表われることがわかる。即ち、形成されるボール直径の変動は、滴下するボール６間の距離変動として、数倍〜十数倍に拡大されて表われる。このことは、ボールを撮像して画像処理で寸法計測する場合、画像分解能が同じであれば、ボール間の距離を算出する方が、直径を算出するよりも数倍〜十数倍精度よく算出できることを示している。従って、ボール間距離を計測してボール直径の変動に換算すれば、精度高くボール直径を捉えることができることになり、ボール間距離を制御量として設定することが有効であることがわかる。 Here, the relationship between the change in the ball diameter and the change in the distance between the balls will be described. FIG. 2 shows an example of the relationship between the ball diameter variation and the distance variation between the balls when four types of balls having different diameters are manufactured. For example, in the case of a ball having a diameter of 300 μm, the distance between the balls is increased by about 9 μm every time the diameter is increased by 1 μm. In the case of a ball having a diameter of 600 μm, the distance between the balls is increased by about 1 μm. It can be seen that as the diameter of the ball is 4 μm longer, the smaller the diameter, the greater the variation in diameter appears as the distance between the balls. That is, the variation in the diameter of the formed ball appears as a variation in the distance between the dropped balls 6 by several times to several tens of times. This means that when measuring the dimensions of an image by imaging the balls, if the image resolution is the same, calculating the distance between the balls is several times to ten times more accurate than calculating the diameter. It shows what you can do. Accordingly, if the distance between the balls is measured and converted into a change in the ball diameter, the ball diameter can be captured with high accuracy, and it can be seen that it is effective to set the distance between the balls as the control amount.

次に、ボール間距離をインラインで算出する方法を詳細に説明する。前述したように、カメラ７の視野内には少なくとも２個のボール６が撮像されるようにし、画像処理でボール６の重心を演算し、ボール６の重心間距離を算出する。精密に距離を算出するためには、光学系の倍率を高くし１画素当たりの分解能を上げることが好ましいが、ボール直径によってボール間距離が異なるので、ボール直径が変わっても視野内に同一数のボールを撮像するとすると、ボール間距離が小さいものほど倍率を上げて撮像することができることになる。このために、カメラ７に倍率変更手段を装着しておくとよく、製造する種々のボール直径に合わせて適宜倍率調整を行うためには、ズームレンズのように連続的に倍率を変えることができるものを装着することが好ましい。また、ストロボランプ８にコリメータを設置して平行光とし、カメラレンズにテレセントリックレンズを使用すると、落下中のボール６がふらついたり曲がったりして作動距離が多少変動しても、測定精度にはほとんど影響を与えないためさらに好ましい。また、何らかの原因でボール６が斜めに落下した場合でも、ボール間距離を正しく算出するためには、上記光学系を例えば直交するように２組配置し、各々の撮像画像から落下角度を算出し、補正するようにするとよい。 Next, a method for calculating the distance between balls in-line will be described in detail. As described above, at least two balls 6 are imaged in the field of view of the camera 7, the center of gravity of the ball 6 is calculated by image processing, and the distance between the centers of gravity of the balls 6 is calculated. In order to calculate the distance accurately, it is preferable to increase the magnification of the optical system and increase the resolution per pixel. However, since the distance between the balls varies depending on the ball diameter, the same number in the field of view even if the ball diameter changes. If the ball is imaged, the smaller the distance between the balls, the higher the magnification can be taken. For this purpose, it is preferable to attach a magnification changing means to the camera 7. In order to adjust the magnification appropriately according to various ball diameters to be manufactured, the magnification can be changed continuously like a zoom lens. It is preferable to wear a thing. In addition, if a collimator is installed on the strobe lamp 8 to produce parallel light and a telecentric lens is used for the camera lens, the measurement accuracy will be almost the same even if the working distance varies slightly due to the falling ball 6 being fluttered or bent. This is more preferable because it does not affect the operation. In addition, even when the ball 6 falls obliquely for some reason, in order to calculate the distance between the balls correctly, two sets of the optical systems are arranged so as to be orthogonal, for example, and the drop angle is calculated from each captured image. It is better to correct it.

ズームレンズにより倍率を調整する場合、撮像素子１画素当たりの実際の測定寸法、即ち画素サイズが連続的に変わるため、都度校正することが必要となる。このため、図３に示すように、その表面に寸法が既知のマーキングが施された校正治具１０を用い、倍率調整後のカメラ７でマーキングを撮像することで、寸法ｓに相当する画素数から画素サイズを正確にかつ即座に算出することができる。マーキングとしては、直径寸法がｓの円形パターンや、複数の点又は線を中心間距離が寸法ｓとなるように形成したパターンを用いるとよい。また、校正治具１０を、その表面がカメラ７に対しボール６の落下ラインとほぼ同じ距離になるように設置すれば、画素サイズの算出にカメラ７からの距離の違いを考慮する必要がなくなるだけでなく、製造前にマーキングに焦点を合わせておくことで、製造中のボール６へピント合わせを行う操作が不要となる。この時、ボールの落下ライン近くに設置して、カメラ７でボール６と同時に撮像するようにすれば、製造中にリアルタイムで画素サイズの校正を行うことも可能となり、気温の変化などによる光学系の変動など誤差要因をキャンセルした精度のよい測定を行うことができる。 When the magnification is adjusted by the zoom lens, the actual measurement size per pixel of the image sensor, that is, the pixel size is continuously changed, so that calibration is required every time. For this reason, as shown in FIG. 3, the number of pixels corresponding to the dimension s is obtained by imaging the marking with the camera 7 after the magnification adjustment using the calibration jig 10 having the marking with the known dimension on the surface thereof. From this, the pixel size can be calculated accurately and immediately. As the marking, it is preferable to use a circular pattern having a diameter dimension of s or a pattern in which a plurality of points or lines are formed so that the distance between centers is the dimension s. Further, if the calibration jig 10 is installed so that the surface thereof is substantially the same distance as the drop line of the ball 6 with respect to the camera 7, it is not necessary to consider the difference in distance from the camera 7 in calculating the pixel size. In addition, focusing on the marking before manufacturing eliminates the need to focus on the ball 6 being manufactured. At this time, if it is installed near the ball drop line and the camera 7 captures the image simultaneously with the ball 6, it is possible to calibrate the pixel size in real time during manufacturing, and the optical system due to changes in temperature, etc. It is possible to perform accurate measurement with error factors such as fluctuations canceled.

また、ボール製造装置によっては、滴下中のボール６が合体することを阻止するため、落下ライン回りにボール６に電気的反発力を付与するための荷電部が設けられたものがある。このような製造設備を用いる場合、ボール落下ラインに校正治具１０を近づけすぎると、電荷などの影響により校正治具１０にボール６が引っ張られて付着したり、ボール経路が大きく曲がったりする不具合が発生することがある。これを防止するために、校正治具１０をセラミックなど電気的な絶縁材とするとよい。また、絶縁材を用いない校正治具１０であっても、カメラ７とボール落下ライン間のカメラ光軸上に、４５度の傾きをもったハーフミラー１１を設け、ハーフミラー１１の反射光軸上で、光路長がカメラ７とボール６間の距離と等しくなる位置に校正治具１０を設置することで、電荷部の影響を受けないようにすることもできる。 Some ball manufacturing apparatuses are provided with a charging portion for applying an electric repulsive force to the ball 6 around the drop line in order to prevent the ball 6 being dropped from coalescing. When such a manufacturing facility is used, if the calibration jig 10 is too close to the ball drop line, the ball 6 is pulled and attached to the calibration jig 10 due to the influence of electric charge or the like, or the ball path is greatly bent. May occur. In order to prevent this, the calibration jig 10 may be an electrical insulating material such as ceramic. Even in the calibration jig 10 that does not use an insulating material, a half mirror 11 having a 45 degree inclination is provided on the camera optical axis between the camera 7 and the ball drop line, and the reflected optical axis of the half mirror 11 is provided. The calibration jig 10 is installed at a position where the optical path length is equal to the distance between the camera 7 and the ball 6 so that the influence of the charge portion can be avoided.

また、画素サイズを製造前に校正するだけでボールを製造する場合には、校正治具１０を移動できるようにし、製造時には電荷部から離れた位置に退避するようにしてもよい。逆に、カメラ７を水平移動あるいは旋回できるようにし、移動後の所定位置において、カメラ７の撮像中心線に対向し、カメラ７からの距離がボール６までの距離と同じで電荷部から離れた位置に校正治具１０を設置するようにしてもよい。また、前記ハーフミラー１１に代えてフルミラーを用い、フルミラーを退避させるようにしてもよい。 Further, when a ball is manufactured simply by calibrating the pixel size before manufacturing, the calibration jig 10 may be moved, and may be retracted to a position away from the charge portion during manufacturing. On the contrary, the camera 7 can be moved horizontally or turned, facing the imaging center line of the camera 7 at a predetermined position after the movement, and the distance from the camera 7 is the same as the distance to the ball 6 and away from the charge part. The calibration jig 10 may be installed at the position. Further, a full mirror may be used in place of the half mirror 11, and the full mirror may be retracted.

ボール間距離は、校正された画素サイズをもとに撮像画像から算出するが、１画面内のボール間距離を平均したり、複数の画面分を平均したりしてデータ処理して算出するとよく、これらをさらに移動平均処理すると、変動を連続的に大きく捉えることができ、操作機器の制御処理が容易になる。なお、ボール間距離の算出は、カメラ７による撮像画像を画像処理して求める方法だけでなく、ボール落下ラインの、落下速度が安定した所定位置において、落下中のボール６をレーザや近接センサや静電容量センサなどの非接触式物体検出センサを用いて検出し、その検出時間間隔をもとにして行うこともできる。この場合のボール距離の測定精度は、センサの応答性とボール６の落下速度の安定性で決まる。 The distance between balls is calculated from the captured image based on the calibrated pixel size, but it is better to calculate the distance between balls within one screen or by averaging multiple screens and processing the data. When these are further subjected to moving average processing, fluctuations can be captured continuously and control processing of the operating device becomes easy. The calculation of the distance between the balls is not limited to a method of obtaining the image captured by the camera 7 by image processing, but the falling ball 6 can be detected by a laser, a proximity sensor, or the like at a predetermined position on the ball drop line where the drop speed is stable. Detection can be performed using a non-contact type object detection sensor such as a capacitance sensor, and the detection time interval can be used. In this case, the measurement accuracy of the ball distance is determined by the responsiveness of the sensor and the stability of the falling speed of the ball 6.

本発明を実施する製造システムの概念図である。It is a conceptual diagram of the manufacturing system which implements this invention. 滴下するボールの直径変動と距離間隔変動の関係を示す図である。It is a figure which shows the relationship between the diameter fluctuation | variation of the ball | bowl to drop, and distance interval fluctuation | variation. マーキングが形成された校正治具の撮像例を示す図である。It is a figure which shows the example of an imaging of the calibration jig | tool with which the marking was formed.

Explanation of symbols

１・・溶融金属、２・・容器、３・・細孔、４・・加振ロッド、５・・振動子、６・・ボール、７・・カメラ、８・・ストロボランプ、９・・制御装置、
１０・・校正治具 1 .... Molten metal, 2 .... Container, 3 .... Pore, 4 .... Excitation rod, 5 .... Vibrator, 6 .... Ball, 7 .... Camera, 8 .... Strobe lamp, 9 .... Control apparatus,
10. ・ Calibration jig

Claims

In the method for producing spherical particles by pouring the melt from the pores in the container, it has an actual production process for producing particles of a predetermined diameter, and a sample production process performed prior to the actual production process,
In the sample manufacturing process, the particle diameter dropped from the orifice and the distance between the particles are measured, and these data are substituted into a predetermined formula representing the correlation between the particle diameter and the inter-particle distance to define a constant in the predetermined formula. Along with the measured particle diameter, the amount of operation to obtain particles with a diameter close to the target value is obtained and used as the initial operation amount of the operation device in the actual manufacturing process,
In the actual manufacturing process, the operating device is operated with the initial operation amount, the inter-particle distance during dropping is measured in-line, and the measured inter-particle distance is substituted into the predetermined formula in which a constant is defined, A method for producing spherical particles, characterized by calculating a particle diameter and controlling an operating device based on the calculated particle diameter.

In the method for producing spherical particles by pouring the melt from the pores in the container, it has an actual production process for producing particles of a predetermined diameter, and a sample production process performed prior to the actual production process,
In the sample manufacturing process, the diameter of particles dropped from the orifice and the distance between the particles are measured, and these data are substituted into a predetermined formula representing the correlation between the particle diameter and the distance between the particles to define the constants in the predetermined formula. Substituting the target value of the particle diameter into the predetermined formula in which the constant is defined, the inter-particle reference distance is obtained, and the manipulated variable for obtaining particles having a diameter close to the target value is obtained based on the measured particle diameter. As the initial operation amount of the operating device in the actual manufacturing process,
In the actual manufacturing process, the operation device is operated with the initial operation amount, the interparticle distance during dropping is measured inline, and the operation device is controlled by comparing the measured interparticle distance with the interparticle reference distance. A method for producing spherical particles.

In the method for producing spherical particles by pouring the melt from the pores in the container, it has an actual production process for producing particles of a predetermined diameter, and a sample production process performed prior to the actual production process,
In the sample manufacturing process, the diameter of particles dropped from the orifice and the distance between the particles are measured, and these data are substituted into a predetermined formula representing the correlation between the particle diameter and the distance between the particles to define the constants in the predetermined formula. In addition, the target value of the particle diameter is substituted into the predetermined formula in which a constant is defined to determine the interparticle reference distance, and the operation of the operation device for setting the interparticle distance in the actual manufacturing process to the calculated interparticle reference distance. A method for producing spherical particles, wherein the amount is determined by a predetermined adjustment rule.

4. The predetermined formula is represented by D = αλ ^1/3 (where D is a particle diameter, λ is a particle distance, and α is a constant). The manufacturing method of the spherical particle as described in above.

The method for producing spherical particles according to claim 1, wherein a plurality of particles being dropped are imaged and a distance between the particles is calculated by image processing.

6. The method for producing spherical particles according to claim 5, wherein a marking having a known dimension set so that the working distance is the same as the dropping line is imaged, and the pixel size after magnification adjustment is automatically calibrated.