JP2004010947A - Intermittent powder-application device and powder compacting machine with lubrication into mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intermittent application device, which stably, surely and quantitatively supplies a predetermined quantity of a powder such as a lubricant used in a mold, to a die, even when the powder is intermittently supplied in an extremely short cycle like a tenth to several seconds or shorter. <P>SOLUTION: This application device for precisely and quantitatively supplying the predetermined quantity of the powder in a short cycle, comprises a powder feeding section, a quantitative sectioning unit connected to the powder feeding section, a drive motor for driving the sectioning unit, the pipeline for pneumatically transporting the powder that have been sectioned from the quantitative sectioning unit, a nozzle for supplying the powder to a part to be coated by spraying, and a clutch mechanism for switching a mode between transmission of the driving force of the above drive motor to the above sectioning unit and disconnection, in the short cycle. <P>COPYRIGHT: (C)2004,JPO

Description

【００５８】
上記表１からも明らかな様に、従来のエアインジェクションタイプの間欠供給装置を使用した場合でも、本発明装置を用いた場合と同程度の微量の間欠供給を実施できるが、本発明装置では切出し量の標準偏差が１／２レベル以下に減少しており、間欠定量供給精度が著しく高められることを確認できる。また、従来から粉体塗料の塗装用として用いられているスクリュータイプの供給装置では、１．０秒以下の短時間の間欠送給が不可能であり、且つ実現可能な間欠サイクルの下限値である１．０秒／回を実施した場合でも、切出し量の標準偏差が非常に大きく、高精度の定量間欠送給にそぐわないことが分る。
【００５９】
以上、本発明の粉体間欠供給装置を、粉末冶金用粉末を型内潤滑成形法によって圧粉成形する際の粉末潤滑剤の間欠供給を代表的に取り上げて説明したが、本発明は、要するに少量の粉末を短い間欠周期で定量的に精度よく送給し得るようにしたところに特徴を有するものであるから、こうした特徴を活かせば、例えば焼結部品のサイジング用潤滑剤の塗布、熱間鍛造における潤滑剤の塗布、錠剤成形による離型剤の塗布、アルミニウムなどの金属容器内面へのフッ素系粉末樹脂などの内面コーティング、オートバイのタイヤ用スポーク内面への防錆用粉体樹脂の塗布など、様々の分野で有効に活用できる。
【００６０】
【発明の効果】
本発明は以上のように構成されており、粉末供給部、該粉末供給部に接続した定量切出し装置、該切出し装置を駆動する駆動モータ、該定量切出し装置から切り出された粉末を気流輸送する輸送管路、該粉末を被塗布部へ噴霧供給するノズルを備えた粉末塗布装置において、特に、駆動モータと定量切出し装置を電磁クラッチを介して接続し、該クラッチの切り替えにより定量切出し装置を短い周期で間欠作動させることによって、所定量の粉末を高精度で間欠塗布し得ることになった。
【００６１】
そして該間欠塗布装置における気流輸送管路に、気流輸送される粉末を摩擦帯電させる帯電部を設け、該帯電部で粉末に与えられる帯電圧によって粉末の送給量を自動的に検知し、送給不足となったときはその信号によってアラーム装置を作動させ、或いは粉末塗布装置を自動停止するような制御機構を設けておけば、塗布不足による欠陥製品の発生を未然に防止することができ、製品歩留りを高めることが可能となる。更には、粉末の供給不足に起因して生じることのある設備への過負荷も軽減できる。
【００６２】
従ってこの間欠塗布装置は、例えば粉末冶金用粉末を圧粉成形する際に、金型内面へ型内潤滑剤を間欠塗布するための装置などとして有効に活用できる。
【図面の簡単な説明】
【図１】本発明に係る粉末の間欠塗布装置を用いた型内潤滑圧粉成形装置の全体構成を示す説明図である。
【図２】帯電部の構成と、帯電圧を利用した粉末供給量の検知・制御機構を例示する説明図である。
【図３】圧粉成形金型装置の具体的な構造と作動機構の例を示す概略説明図である。
【図４】圧粉成形金型装置の具体的な構造と作動機構の例を示す概略説明図である。
【図５】圧粉成形金型装置の具体的な構造と作動機構の例を示す概略説明図である。
【図６】圧粉成形金型装置の具体的な構造と作動機構の例を示す概略説明図である。
【図７】圧粉成形金型装置の具体的な構造と作動機構の例を示す概略説明図である。
【図８】粉末潤滑剤切出し部におけるタイマー作動例を示す説明図である。
【図９】帯電部で検知される帯電電圧の変動パターンの一例を示す図である。
【符号の説明】
１　　粉末潤滑剤供給ホッパー
２　　撹拌翼
３　　撹拌用モータ
４　　加振機
５　　定量切出し用スクリュー
６　　駆動モータ
７　　電磁クラッチ
８　　定量供給ホッパー
９　　粉末気流送給器
１０　帯電部
１１　アラーム装置
１２　圧粉成形金型装置
１３　自動制御部
１４　流動エア供給部
１５　帯電信号処理機構
Ｌ　　送給管路
Ｄ　　ダイス
Ｐ_１、Ｐ_２　パンチ
Ａ　　金属粉末供給装置
Ｎ　　粉末潤滑剤供給ノズル
Ｒ　　ロッド
Ｍｅ　粉末冶金用金属粉末[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an intermittent powder applying apparatus and an in-mold lubricating compacting apparatus for powder metallurgy equipped with the apparatus, and particularly to a method for intermittently supplying and applying a predetermined amount of powder in a short cycle with high accuracy. The present invention relates to an intermittent coating device devised as described above and a powder compacting device in which the device is applied to the application of an in-mold lubricant for powder metallurgy.
[0002]
The present invention is particularly effective as an intermittent coating device for applying a powdered in-mold lubricant to the inner surface of a mold when compacting metal powder for powder metallurgy by employing an in-mold lubrication method. Since it can be utilized, the following description will be made mainly on the intermittent application of the lubricant in the powdery mold. However, the present invention is not limited to such applications as a matter of course, and can be effectively applied to all applications in which it is necessary to apply a predetermined amount of powder intermittently and accurately in a short cycle.
[0003]
[Prior art]
When compacting metal powder for powder metallurgy using a mold, an appropriate amount of a lubricant is usually mixed with the metal powder to smoothly perform the compacting, and the metal powder and the metal powder are mixed with the mold. A method of increasing the lubricity between the inner surfaces is employed. However, the part that needs lubrication most is the contact part between the metal powder and the inner surface of the mold, and the role of the internal lubricant plays a relatively small role.
[0004]
On the other hand, the lubricant mixed into the metal powder becomes an impurity and causes a reduction in the density and strength of the green compact, and furthermore, it takes time for dewaxing during sintering. desired. For these reasons, recently, the in-mold lubrication molding method of minimizing the amount of internal lubricant used in the metal powder and applying the in-mold lubricant to the inner surface of the mold to perform compaction molding has been proposed. It is becoming popular.
[0005]
In addition, as a method of applying the in-mold lubricant to the inner surface of the mold, in the case of a liquid lubricant or a slurry-like lubricant, brush coating or spray coating is employed. When a solid lubricant is used at room temperature as described above, a method in which the lubricant is powdered and uniformly adhered to the inner surface of a mold by an electrostatic adhesion method is widely used.
[0006]
When the lubricant in the mold is applied by the electrostatic adhesion method, the lubricant in the mold is applied to the inner surface of the mold in synchronization with the compacting cycle that is repeatedly performed in a very short cycle of, for example, 3 to 30 times / minute. It is difficult to carry out the molding with high accuracy, and if so, the amount of lubricant attached may fluctuate and molding failure may occur. For this reason, it is necessary to establish a technique capable of reliably supplying a necessary and sufficient amount of the lubricant in a constant amount in accordance with the short compacting cycle and uniformly applying the lubricant to the inner surface of the mold.
[0007]
Under such circumstances, for example, Japanese Patent Application Laid-Open No. 2001-220602 proposes an in-mold lubricant applying apparatus using a powder circulation channel, in which powdery lubricant is continuously circulated in the circulation channel. On the other hand, there is disclosed a method in which the flow path is switched for a predetermined time during the application of the lubricant, and the spray is supplied to the portion to be coated.
[0008]
However, since this method is not basically a method of performing quantitative cutout, it is not only difficult to confirm the amount of spray supply each time, but also it is not always possible to maintain the amount of spray supply constant. That is, in this method, since the powder is constantly circulated together with the airflow (carrier gas), a part of the powder adheres to the pipe wall surface of the circulation line in the circulation process, and the adhered and deposited powder falls off at a certain time. Therefore, the powder concentration in the circulation channel fluctuates considerably. In addition, powder blocking due to static electricity generated by friction during circulation is inevitable, and together with this, the concentration and particle size of the powder circulating in the flow path fluctuate considerably. The amount of powder lubricant supplied varies considerably. Therefore, depending on the spray switching timing, the in-mold lubricant may be insufficiently supplied or excessively supplied, which may adversely affect the stable operation of the compacting itself.
[0009]
On the other hand, in the field of powder coatings, various devices have been proposed in which a predetermined amount of powder coating is supplied stably and continuously to a spray nozzle portion by a pneumatic transport while quantitatively cutting out the powder coating. For example, Japanese Patent Application Laid-Open No. HEI 8-29006 discloses a screw-type quantitative cut-out device for powder coating. Then, the screw of the cutting section is directly connected to the deceleration motor, and the screw is rotated for the driving time of the motor, so that the fixed amount cutting can be performed.
[0010]
However, since the powder coating apparatus is basically based on the premise that continuous coating is performed for several minutes to several tens of minutes, it is difficult to apply the powder coating apparatus to a powder metal compacting apparatus which is usually repeatedly performed at an intermittent coating cycle of about 0.1 second. . In particular, in the above powder coating apparatus, the powder supply amount after reaching the steady spray supply state is kept almost constant, but the powder supply amount when the drive motor, which is the drive source of the fixed amount cutting screw, starts up is not. Since it is stable and considerable fluctuations are unavoidable, and the rise time alone requires a time in seconds, the intermittent operation cycle is extremely short, for example, 0.1 seconds to several seconds. It is virtually impossible to apply to supply.
[0011]
Furthermore, Japanese Patent Application Laid-Open No. 2001-29848 discloses a method of preventing spray dripping of supplied powder by performing a control operation using a plurality of electromagnetic valves when performing a screw type fixed amount cutout. . However, also in this method, basically, the intermittent supply of powder is performed by switching a plurality of electromagnetic valves while circulating the powder, and the problem derived from the circulation described above is kept as it is, and for example, several seconds or less. It is not possible to respond to stable intermittent quantitative supply in a short cycle.
[0012]
Further, in any of these methods, a mechanism for automatically detecting whether a predetermined amount of powder has been surely sent in the direction of the spray nozzle is not attached. If the powder lubricant for internal lubrication is not sprayed properly, seizure will occur in the compacting mold and the quality of the compacted body will be impaired, and the mold and the press device will be damaged. .
[0013]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and its purpose is, for example, when performing in-mold lubrication molding for powder metallurgy, for example, 1/10 to several seconds, or very short To provide an intermittent coating device capable of stably and surely supplying a predetermined amount of powder even when intermittently supplying powder such as an in-mold lubricant into a mold in a short cycle. An object of the present invention is to provide a powder compacting apparatus that effectively utilizes the characteristics of the apparatus for in-mold lubrication for powder metallurgy.
[0014]
[Means for Solving the Problems]
The intermittent powder coating apparatus according to the present invention that can solve the above-mentioned problems includes a powder supply unit, a fixed amount cutout device connected to the powder supply unit, a drive motor driving the cutout device, and a cutout from the fixed amount cutout device. A transport pipe for air-flow transporting the powder, a nozzle for spraying the powder to the coated portion, and a clutch mechanism for repeating transmission and disconnection of the driving force from the drive motor to the cutting device in a short time cycle. The gist exists where it is.
[0015]
In the intermittent coating apparatus of the present invention, a charging section for charging the powder is provided in the airflow transport pipe and / or the spray supply nozzle, so that the powder can be electrostatically attached to an object to be coated. Is recommended as a preferred embodiment. Further, the charging unit is provided in the airflow transport conduit and configured to charge the powder by frictional charging, and the charging voltage can be detected by a detection device that detects a charged voltage provided by the charging unit. Alternatively, a control device is provided in addition to the detection device, and when the charging voltage detected by the detection device is out of the set charging voltage range previously input to the control device, the abnormality of the charging voltage is detected. It is preferable to provide a mechanism for operating the alarm device so that the operator can immediately know the abnormality of the electrostatic adhesion amount of the powder. In addition, it is preferable that the control device is provided with an automatic stop mechanism that stops the facility at the same time as detecting the abnormality of the electrostatic adhesion amount because a problem caused by the abnormality of the powder supply amount can be avoided beforehand. .
[0016]
Therefore, this intermittent application device can be effectively used as an apparatus for intermittently applying the in-mold lubricant to the inner surface of the mold when the powder for powder metallurgy is compacted.
[0017]
Further, the powder compacting apparatus according to the present invention is configured such that the above-mentioned intermittent powder applying apparatus is connected to a powder compacting mold, and the clutch mechanism is used to measure powder in accordance with the compacting cycle of the mold. The gist lies in that a control mechanism for intermittently driving the cutting device and intermittently supplying the powder lubricant from the powder spray supply nozzle to the inner surface of the mold is provided.
[0018]
In continuously operating the compacting with a short intermittent cycle using this device, when the charging voltage detected by the detection device is out of the set charging voltage range previously input to the control device, If a mechanism to stop the operation by detecting an abnormality of the charged voltage and activating the alarm device or transmitting an abnormal signal to the drive source of the powder compacting mold is provided, especially when the supply of the powder lubricant is insufficient, This is preferable because it is possible to prevent poor compaction and seizure accidents caused by insufficient lubrication of the mold.
[0019]
Embodiments and Examples of the Invention
As described above, the present invention has a basic feature in that when a powder is intermittently supplied in an extremely short cycle, a predetermined amount of powder can be stably and surely supplied in a short cycle. The type of powder to be supplied is not particularly limited, but the above-mentioned features of the present invention are most effectively utilized when the powder compaction for powder metallurgy is performed by using an in-mold lubrication method. Since the intermittent supply of the in-mold lubricant is automatically performed, the present invention will be more specifically described below with reference to drawings showing representative examples, mainly on the in-mold lubrication compacting method. To go.
[0020]
However, the present invention is not necessarily limited by the following illustrative examples, and can be implemented with appropriate modifications within a range that can be adapted to the gist of the preceding and the following descriptions. Within the scope.
[0021]
FIG. 1 is a schematic explanatory view showing one embodiment of the present invention, and shows a case in which a fixed-quantity cutting feeder using a screw mechanism and an air conveying / spraying mechanism are employed to perform in-mold lubrication compaction.
[0022]
In the figure, 1 is a powder lubricant supply hopper, 2 is a stirring blade, 3 is a stirring motor, 4 is a vibrator, 5 is a screw for fixed amount cutting, 6 is a drive motor, 7 is an electromagnetic clutch, and 8 is a fixed amount supply hopper. , 9 is a powder air flow feeding device, 10 is a charging unit, 11 is an alarm device, 12 is a powder compacting mold device provided with a spray nozzle and the like, and 13 is an automatic control unit.
[0023]
In this apparatus, a screw 5 for fixed quantity cutting is connected to a lower portion of a powder lubricant supply hopper 1 provided with a stirring blade 2 driven by a stirring motor 3 and a vibrator 4. The screw 5 is connected to a drive motor 6 via an electromagnetic clutch 7 to operate the compacting mold apparatus 12 (opening of the mold → application of lubricant in the mold → supply of raw material powder) as described later. → Powder molding → Die release → Powder compact removal) In accordance with the cycle, the electromagnetic lubricant is intermittently driven by the electromagnetic clutch 7 in order to supply a fixed amount of powder lubricant in the mold direction.
[0024]
That is, the screw 5 connected to the lower portion of the powder lubricant supply hopper 1 is intermittently driven in accordance with the switching cycle of the electromagnetic clutch 7 and intermittently sends out a predetermined amount of the powder lubricant toward the supply hopper 8. In the figure, reference numeral 14 denotes a flowing air device, in which the powder lubricant flowing down from the powder lubricant supply hopper 1 is clogged or hangs on the shelf below the hopper 1 or in the communication portion with the screw 5 and fixed quantity cutting is impossible. In order to prevent stabilization, air for flow is supplied from below the communication portion, and a function of stabilizing a constant amount of powder lubricant in accordance with the rotation of the screw 5 is achieved.
[0025]
The powder lubricant cut out from the tip of the screw 5 into the fixed amount supply hopper 8 by a predetermined amount is sucked in the powder flow feeder 9 in the direction of the transport line L by a carrier gas (usually air) by a venturi mechanism or the like. It is discharged and the entire amount is transported downstream.
[0026]
A charging unit 10 is provided on the transport line L on the upstream side of the powder compacting die apparatus 12, and the powder lubricant transported in the line L is charged in the process of passing through the charging unit 10. Then, it is sent to the powder compacting die apparatus 12. For example, as shown in FIG. 2, the charging portion 10 has an inner wall surface made of a material having a high chargeability such as polyfluoroethylene, and friction between the inner peripheral surface and the powder during the passage of the powder through the charging portion. This causes the powder to be charged. In this apparatus, in order to keep the amount of charge given to the powder constant, only the inner peripheral wall of the charging unit 10 is made of a highly chargeable material, and the transport conduit L other than the charging unit 10 is made of a material which is unlikely to cause frictional charging. Constitute.
[0027]
Therefore, in this charging unit 10, as long as the amount and the flow rate of the powder transported in the pipeline L are constant, a constant charged voltage is applied to the powder, and the charged amount is used as a charging signal. Always detected. Then, when an abnormality occurs in the powder cutout line, the charged voltage fluctuates due to the fluctuation of the amount of the powder passing through the charging unit 10, and this fluctuation is immediately detected by the calculation detecting unit. Then, the signal is immediately sent to the alarm device or a stop signal is issued to the molding die apparatus 12, which will be described later.
[0028]
As a means for charging the powder, in addition to the frictional charging method as described above, for example, a corona discharge unit is provided at the tip of a nozzle or the like when the powder is blown into the mold cavity, and the powder that is transported by air flow is provided. It is also possible to employ a method of charging by corona discharge. In this case, the detection by the alarm device is not a charged voltage by corona discharge, but is performed by providing a separate frictional charging unit.
[0029]
The powder charged by the charging unit 10 is then blown into a mold from a powder supply nozzle arranged facing the powder compacting die apparatus 12, and is electrostatically applied to the inner surface of the cavity.
[0030]
3 to 7 are schematic cross-sectional explanatory views illustrating a specific structure and an operation mechanism of the compacting die apparatus 12, and include a fixed die D and a vertically movable punch P. ₁ , P ₂ And the inner peripheral wall of the die D and the punch P ₁ , P ₂ Is filled with metal powder for powder compaction into a cavity surrounded by upper and lower surfaces of a punch P. ₁ , P ₂ The powder compacting is performed by pressing from above and below.
[0031]
In the figure, A indicates a metal powder supply device, and N indicates a powder lubricant supply nozzle attached at the tip end thereof. ₂ Is lowered to a predetermined position to secure a predetermined cavity shape. First, the powder lubricant is supplied from the powder lubricant supply nozzle N into the cavity, and the static electricity given by the charging unit 10 is used. Apply powder lubricant to the inner wall of the cavity. At this time, the metal powder Me, which is a raw material for compacting, is charged into the metal powder supply device A (FIG. 3).
[0032]
Next, the supply of the powder lubricant from the nozzle N is stopped, and the rod R is operated to advance the metal powder supply device A to supply a predetermined amount of metal powder into the cavity (FIG. 4). Thereafter, when the rod R is operated to retract the metal powder supply device A and the nozzle N from the cavity position, the mold cavity is filled with a predetermined amount of metal powder. Subsequently, as shown in FIG. ₁ And, if necessary, the lower punch P ₂ Is also raised at the same time to perform compacting (FIG. 6).
[0033]
After the compacting is completed, the punch P ₁ And the die D is lowered (and / or the punch P ₂ Is raised) to expose the compact S from the cavity, and then the compact S is discharged out of the mold apparatus 12 by a pusher (not shown) (FIG. 7).
[0034]
Then, after the discharge of the green compact is completed, the process returns to the step shown in FIG. 3 again, and the rod R is actuated to advance the powder lubricant supply nozzle N to the cavity position of the mold. And apply it to the inner surface of the cavity.
[0035]
Such application of powder lubricant to the inner surface of the cavity → quantitative supply of metal powder → punch P ₁ , P ₂ , And a series of steps consisting of taking out the green compact S is taken as one cycle, and the green compact is intermittently repeated at a very short cycle of, for example, 3 to 30 times / min. Compacting is performed continuously.
[0036]
In order to smoothly perform such an intermittent operation, it is necessary to stably supply a predetermined amount of powder lubricant into the cavity and perform intermittent application in accordance with the above-described intermittent operation cycle of the mold apparatus 12. However, at this time, the intermittent powder supply device as illustrated in FIG. 1 according to the present invention exerts its function without regret and guarantees a stable supply of the powder lubricant. Hereinafter, the intermittent feeding mechanism of the powder lubricant will be described again along the example shown in FIG.
[0037]
This equipment is configured so that it can be centrally managed by an automatic control unit 13. The automatic control unit 13 includes the stirring motor 3, the vibrator 4, the drive motor 6 for the fixed quantity cutting screw 5, the electromagnetic clutch 7, Driving sources such as a powder air flow feeding device 9 and a flowing air supply unit 14 are electrically connected, and a voltage detection unit and the like of a charging unit 10 and an alarm device 11, and furthermore, the Punch P ₁ , P ₂ And a metal powder supply device A, a rod R for moving the powder supply nozzle N forward and backward, etc., are electrically connected, so that the above-mentioned series of steps can be controlled and operated automatically.
[0038]
More specifically, the automatic control unit 13 includes, for example, timers 1 to 4 and air adjusters 1 and 2 and the like. ₁ , P ₂ The timing of the powder lubricant supply including the intermittent drive of the electromagnetic clutch 7 is adjusted in accordance with the intermittent operation cycle such as the vertical movement or reciprocation of the rod R, the opening and closing of the powder lubricant supply nozzle N, and the like. Further, in the timers 2 to 4, the pre-injection time is used in the timer 2, the cut-out time is used in the timer 3, and the timer 3 is used in the timer 3 so that the entire amount of the powder lubricant quantitatively cut out from the screw 5 can be reliably fed to the downstream side. The post-injection time is adjusted, and the air adjusting unit 1 adjusts the air pressure for conveyance, and the air adjusting unit 2 adjusts the air pressure for flow.
[0039]
Then, these are punched by the punch P in the powder molding die apparatus 12. ₁ , P ₂ The intermittent supply of the powder lubricant to the mold cavity is performed by operating the metal powder supply device A and the powder supply nozzle N in accordance with an intermittent operation cycle such as an advance / retreat operation source of a rod R for moving the powder supply nozzle N forward / backward.
[0040]
For example, FIG. 8 is an explanatory diagram showing an example of a timer operation in the powder lubricant cutting section. The drive motor 6 is continuously driven, and the electromagnetic clutch 7 is intermittently operated according to the powder lubricant supply timing. A fixed amount of the powder lubricant is cut out from the screw 5. At this time, the conveying air and the auxiliary air are supplied for a relatively long time before and after the operation time of the electromagnetic clutch 7 so that all of the fixedly cut powder lubricant can be reliably sent to the downstream side. The stirring motor 3 and the vibrator 4 are operated slightly extended after the stop of the electromagnetic clutch 7 so that the powder lubricant cut out in the next step is surely sent to the fixed quantity cutting screw 5.
[0041]
Such an intermittent driving time is automatically controlled by the above-described timer mechanism. The set time of the timer can be arbitrarily adjusted according to the size and shape of the green compact, the target productivity, and the like, and should not be interpreted restrictively. However, as a general guide, for example, T ₁ Is 0.1 to 10 seconds, T ₂ Is 0.1 to 3 seconds, T ₃ Is 0.1 to 5 seconds (accuracy is preferably guaranteed in units of 0.01 seconds), T ₄ Is about 0.1 to 3 seconds.
[0042]
That is, according to the present example, the constant-rate cutting device is connected to the drive motor via the electromagnetic clutch to intermittently drive and realize stable feeding using the transport air. Intermittent powder compaction employing in-mold lubrication, which has been difficult, can be efficiently performed in a very short cycle.
[0043]
In the illustrated example, an example in which the most versatile screw mechanism is used as the fixed-quantity cutting device has been described. However, the present invention is not limited to this. It is possible. Further, the specific structure of the powder supply hopper 1 can be arbitrarily changed in accordance with the cutout mechanism of the fixed amount cutout device, and the specific configuration of the air flow feeding device 9 and the like is essential. The specific structure and the like are not limited at all as long as it has a function of reliably transporting the entire amount by air flow.
[0044]
By the way, if the quantitative supply of the powder lubricant is actually performed and the in-mold lubrication and the compacting are performed by using the present invention, the fluctuation of the cut-out amount can be suppressed as small as possible by the intermittent quantitative cut-out using the electromagnetic clutch. However, depending on fluctuations in the flow characteristics of the powder lubricant due to changes in the humidity of the atmosphere, etc., or fluctuations in the fixed-volume cutout portion, including slight pressure fluctuations in the air for feeding, the amount of powder lubricant to be fed may be delicate. May change to In particular, when the supply amount of the powder lubricant is insufficient, the inner surface of the compacting mold becomes insufficient in the mold lubrication, and the compacting molding failure such as seizure or insufficient compaction occurs on the inner surface of the mold. Or damage the mold.
[0045]
Therefore, in a preferred embodiment of the present invention, in consideration of such a situation, the supply amount of the intermittently supplied powder lubricant is always detected, and when a change in the supply amount exceeding an allowable range occurs, the change is immediately detected. It is desirable that an alarm device immediately informs the operator or an automatic stop mechanism for immediately stopping the operation of the compacting die apparatus is provided.
[0046]
FIG. 2 described above shows that when the above-described abnormal supply of the powder lubricant, particularly when the supply is insufficient, the abnormality is automatically detected and the operator is notified by an alarm mechanism, or more preferably, A mechanism is shown in which at least the operation of the compacting mold apparatus is automatically stopped by a detection signal, so that occurrence of defective molding and damage to the mold apparatus can be prevented beforehand.
[0047]
That is, as described above with reference to FIG. 2, in the illustrated charging unit 10, the inner peripheral surface is formed of a highly chargeable material such as polyfluoroethylene, and the powder that passes through the inside of the charging unit 10 with the gas is mixed with the inner peripheral surface. A mechanism for charging by friction is adopted. This charging mechanism has the advantage that the powder can be charged simply and quickly without increasing the flow path resistance so much. In addition, the charging amount of the powder passing through the charging section 10 can be easily changed from the outside as a charged voltage. It has the advantage of being detectable. Furthermore, the present inventors have confirmed that, when such frictional charging is employed, if the charged voltage taken out of the charging unit 10 is detected, the feed amount of the powder conveyed while being charged can be reduced. It was confirmed that it could be detected accurately.
[0048]
In the present invention, based on such knowledge, when the friction charging method is adopted, the charged amount of powder is detected by measuring the charged voltage at the time of powder feeding in the friction charging unit, and the detection signal is detected. Based on this, the change in the powder feed rate is immediately detected, and the change is immediately notified to the operator. In particular, when the feed rate becomes insufficient, the compacting die apparatus is automatically stopped. Effective use as a safety mechanism is recommended as a preferred embodiment.
[0049]
Specifically, as shown in FIG. 2, a charging signal processing mechanism 15 is provided in addition to the charging unit 10, and the arithmetic processing unit provided in the processing mechanism 15 is used to transfer the powder in a steady state. The charging voltage corresponding to the amount of charging generated in the step S1 is previously input as a standard voltage. Then, at the time of intermittent feeding of the powder, the actual charging voltage generated when the powder is charged and fed is configured to be converted as necessary and can always be detected, and the charging voltage is compared with a preset standard voltage. To determine the amount of powder to be conveyed. When the charging voltage of the powder during the actual transport falls below the allowable range of the preset standard voltage, the signal is transmitted to the intermittent drive source of the powder compacting mold apparatus 12 and the mold apparatus 12 Is instructed to stop driving. Although the charging signal processing mechanism 15 can be provided independently of the charging unit 10 as shown in the figure, it is usually incorporated in the automatic control unit 13 as shown in FIG. Is done.
[0050]
FIG. 9 is a diagram illustrating a variation pattern of the charging voltage at this time. The charging voltage detected by the charging unit at the time of intermittent feeding in a normal state is approximately 8 V, which is almost constant, and this charging voltage is maintained. As long as the intermittent feed amount of powder (feed amount per cycle) is kept constant. However, when the amount of the powder passing through the charging unit is reduced due to an abnormality in the powder cutting unit or the like, the state immediately appears as a reduction in the charging voltage. Therefore, the lower limit value of the charging voltage in the normal state is input to the charging signal processing mechanism 15 in advance, and when the measured charging voltage falls below the set value, the signal is transmitted to the alarm mechanism 11 or A control line may be set so as to output as a drive stop signal of the powder molding die device 12.
[0051]
If such an automatic detection mechanism and an automatic stop mechanism are attached, even if a slight supply amount abnormality occurs in the powder lubricant that is conveyed from the cutout portion and sent to the mold apparatus 12, the abnormality can be prevented. In addition to being able to detect quickly, by operating the automatic stop mechanism, it is possible to prevent the occurrence of defective molded products, and to prevent damage to the mold equipment due to seizure of the mold, etc. It is preferable because it is possible.
[0052]
Next, a comparison of the change in the feed rate per cycle when the powder lubricant was intermittently fed using an intermittent feeder using an electromagnetic clutch and the change in the same feed rate when the conventional method was used was compared. In order to do this, the following experiment was performed.
[0053]
That is, using zinc stearate (average particle size: 12 μm) as the powder, the intermittent feeding device of the present invention as shown in FIG. 1, a commercially available air injection type intermittent feeding device, and a screw type powder Table 1 shows the results of comparing the amount of variation in the amount of powder fed when intermittent feeding was performed using a paint coating apparatus. However, the specifications of each device were as follows, and the number n was set to 20 in each case.
[0054]
[Intermittent feeding device of the present invention]
A method in which a screw cutting method is adopted and a method of conveying compressed air as a carrier gas is used, a cutting amount: 0.03 to 1.0 g / time, an intermittent feeding switching time: 0.2 to 1.0 seconds, a screw rotation speed. 20-160 rpm.
[0055]
[Commercial air injection intermittent supply device]
A method in which the powder is sucked by a carrier gas and the amount of application is adjusted by the suction time, the amount of application: 0.03 to 1.0 g / time, the suction time: 0.01 to 0.30 seconds.
[0056]
[Screw type powder coating equipment]
Screw-type quantitative cut-out method, cut-out amount: 0.5 to 1.0 g / time, intermittent feed switching time: 1.0 second (short-time switching of 1.0 second or less is practically impossible), screw rotation speed; 10-20 rpm.
[0057]
[Table 1]

[0058]
As is clear from the above Table 1, even when the conventional air injection type intermittent supply device is used, the same small amount of intermittent supply can be performed as in the case of using the device of the present invention. It can be confirmed that the standard deviation of the amount is reduced to less than 1/2 level, and the accuracy of intermittent quantitative supply is remarkably improved. In addition, in the screw type feeding device conventionally used for coating powder coating, intermittent feeding for a short time of 1.0 second or less is impossible, and the lower limit of an intermittent cycle that can be realized is used. It can be seen that even when a certain 1.0 second / time is performed, the standard deviation of the cut-out amount is very large and does not match high-precision quantitative intermittent feeding.
[0059]
As described above, the intermittent powder supply apparatus of the present invention has been described by taking up the intermittent supply of the powder lubricant when the powder for powder metallurgy is compacted by the in-mold lubrication molding method as a representative example. It is characterized by being able to quantitatively and precisely feed small amounts of powder in short intermittent cycles, and by utilizing these characteristics, it is possible to apply lubricants for sizing of sintered parts, Application of lubricant in forging, application of release agent by tableting, coating of inner surface of metal container such as aluminum with fluorine powder resin, application of rust prevention powder resin to inner surface of motorcycle tire spokes, etc. , Can be effectively used in various fields.
[0060]
【The invention's effect】
The present invention is configured as described above, and includes a powder supply unit, a fixed amount cutout device connected to the powder supply unit, a drive motor for driving the cutout device, and a transportation for pneumatically transporting the powder cut out from the fixed amount cutout device. In a powder coating apparatus provided with a pipeline and a nozzle for spraying the powder to a portion to be coated, in particular, a drive motor and a fixed-quantity cutting device are connected via an electromagnetic clutch, and the fixed-size cutting device is short-cycle by switching the clutch. As a result, the predetermined amount of powder can be intermittently applied with high precision.
[0061]
A charging unit for frictionally charging the powder to be transported by airflow is provided in the airflow transport pipe in the intermittent coating device, and the charged amount of the powder is automatically detected by a charged voltage applied to the powder at the charging unit. If there is a shortage of supply, an alarm device is activated by that signal, or if a control mechanism that automatically stops the powder coating device is provided, it is possible to prevent the occurrence of defective products due to insufficient coating, The product yield can be increased. Further, overload on equipment which may occur due to insufficient supply of powder can be reduced.
[0062]
Therefore, the intermittent coating device can be effectively used as a device for intermittently applying the in-mold lubricant to the inner surface of the mold when, for example, compacting powder for powder metallurgy.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the overall configuration of an in-mold lubrication compacting apparatus using an intermittent powder applying apparatus according to the present invention.
FIG. 2 is an explanatory diagram illustrating a configuration of a charging unit and a mechanism for detecting and controlling a powder supply amount using a charged voltage.
FIG. 3 is a schematic explanatory view showing a specific structure of a compacting die apparatus and an example of an operating mechanism.
FIG. 4 is a schematic explanatory view showing an example of a specific structure and an operation mechanism of a compacting die apparatus.
FIG. 5 is a schematic explanatory view showing a specific structure of a compacting die apparatus and an example of an operating mechanism.
FIG. 6 is a schematic explanatory view showing a specific structure of a compacting die apparatus and an example of an operating mechanism.
FIG. 7 is a schematic explanatory view showing an example of a specific structure and an operation mechanism of the powder molding die apparatus.
FIG. 8 is an explanatory diagram showing an example of a timer operation in a powder lubricant cutout section.
FIG. 9 is a diagram illustrating an example of a fluctuation pattern of a charging voltage detected by a charging unit.
[Explanation of symbols]
1 Powder lubricant supply hopper
2 stirring blade
3 Stirring motor
4 Exciter
5 Screw for quantitative cutout
6 Drive motor
7 Electromagnetic clutch
8 Constant feed hopper
9 Powder air flow feeder
10 Charging part
11 Alarm device
12 Powder compaction mold equipment
13 Automatic control unit
14 Flowing air supply unit
15 Charged signal processing mechanism
L delivery line
D dice
P ₁ , P ₂ punch
A Metal powder supply device
N powder lubricant supply nozzle
R rod
Me Metal powder for powder metallurgy

Claims (7)

A powder supply unit, a fixed-rate cutting device connected to the powder supply unit, a drive motor for driving the cut-out device, a transport conduit for pneumatically transporting the powder cut from the fixed-rate cutout device, and a spray supply of the powder to a portion to be coated. An intermittent powder applying apparatus, comprising: a clutch mechanism for switching between transmission and disconnection of a driving force from the drive motor to the cutting device in a short time cycle. The intermittent coating device according to claim 1, wherein a charging unit that charges the powder is provided in the airflow transport pipe and / or the spray supply nozzle. 3. The intermittent power supply according to claim 2, wherein the charging unit has a function provided in the airflow transport pipe to charge the powder by frictional charging, and includes a detection device that detects a charged voltage provided by the charging unit. 4. Coating device. A control device and an alarm device are provided in addition to the detection device, and when a charged voltage detected by the detection device is out of a set charged voltage range previously input to the control device, the charged voltage is The intermittent application device according to claim 3, further comprising a control mechanism that detects an abnormality of the device and activates an alarm device and / or stops the application device. The intermittent application device according to any one of claims 1 to 4, wherein the intermittent application device is used for applying an in-mold lubricant to an inner surface of the mold when the powder for powder metallurgy is compacted. The apparatus according to claim 4 or 5, wherein the apparatus is connected to a compacting mold apparatus, and the clutch mechanism intermittently drives the powder fixed quantity cutting apparatus in accordance with the compacting cycle of the compacting apparatus. And a control mechanism for intermittently supplying the powder lubricant from the spray supply nozzle to the inner surface of the mold. When the charged voltage detected by the detecting device is out of the set charged voltage range previously input to the control device, a mechanism for detecting an abnormality of the charged voltage and stopping the operation of the compacting die apparatus. The in-mold lubrication compacting apparatus according to claim 6, further comprising:

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