JP7743016B2 - Heating device and heating method - Google Patents
Heating device and heating methodInfo
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Description
本発明は、短時間かつ均一に被加熱物を内部まで加熱できる加熱装置及び加熱方法に関する。 The present invention relates to a heating device and heating method that can heat an object to its interior uniformly and in a short time.
従来、ＣＦＲＰ（炭素繊維強化複合材料）、ＧＦＲＰ（ガラス繊維強化複合材料）を含む樹脂等のワーク（被加熱物）に対し、赤外線を用いた急速加熱を行うと、被加熱物の表面が優先して加熱されるため、被加熱物の表面と中心とで温度差が生じ、被加熱物全体を均一に加熱することが困難であった。さらに、加熱時の温度制御のため、放射温度計で温度測定をしようとしても、赤外線の散乱光が放射温度計の測定領域（赤外領域）と重複し、精度良く温度測定を行うことができなかった。特に、厚さが２ｍｍ以上の、一般に厚物と呼ばれる被加熱物を急速加熱しようとすると、被加熱物の表面と中心とで数１０℃以上の大きな温度差が生じる。この温度差は、加熱後に行われるプレス成形等の工程において品質の低下を招く一因となっていた。そのため、これまで厚物の加熱は、時間を掛けてゆっくりと加熱することで、試料の表面と中心との温度差を低減させることで対応されており、生産性が悪かった。 Conventionally, when infrared light is used to rapidly heat workpieces (heated objects) made of resins, including CFRP (carbon fiber reinforced composite material) and GFRP (glass fiber reinforced composite material), the surface of the object heats preferentially, resulting in a temperature difference between the surface and center of the object, making it difficult to uniformly heat the entire object. Furthermore, even when attempting to measure the temperature using a radiation thermometer to control the temperature during heating, the scattered infrared light overlaps with the measurement range (infrared region) of the radiation thermometer, making accurate temperature measurements impossible. In particular, when attempting to rapidly heat what are commonly called thick objects, i.e., objects with a thickness of 2 mm or more, a large temperature difference of several tens of degrees Celsius or more occurs between the surface and center of the object. This temperature difference is one of the factors that leads to reduced quality in processes such as press molding that are performed after heating. For this reason, thick objects have traditionally been heated slowly over a long period of time to reduce the temperature difference between the surface and center of the sample, resulting in poor productivity.
そのような中、特許文献１には、加熱炉内でコンベアによりワークを搬送しながら、上流の第１加熱域において、ワークの表層温度を目標温度まで急速に昇温させ、第１加熱域の下流の均熱域において、ワークの表層温度の急降下を抑制する程度に加熱温度を制限して、ワークの表層側から内部側への伝熱によりワークの内部温度を上昇させ、さらに下流の第２加熱域において、表層温度を目標温度まで再び昇温させてワークの表層温度及び内部温度が目標温度範囲内となるように加熱することで、ワークの表層と内部とで温度差が小さくなるように加熱する技術が開示されている。 Patent Document 1 discloses a technology for heating workpieces so that the temperature difference between the surface and interior of the workpiece is small, by transporting the workpieces on a conveyor within a heating furnace in a first heating zone upstream, rapidly raising the surface temperature of the workpiece to a target temperature, limiting the heating temperature in a soaking zone downstream of the first heating zone to a level that prevents a sudden drop in the surface temperature of the workpiece, and raising the internal temperature of the workpiece by heat transfer from the surface side to the interior of the workpiece, and then further downstream in a second heating zone, raising the surface temperature again to the target temperature, heating the workpiece so that the surface and internal temperatures are within the target temperature range.
しかし、特許文献１で開示される加熱方法は、加熱炉の各加熱域における温度及び昇温時間（コンベアの速度）の設定をして加熱しているに過ぎない。そのため、ワークの形状等の条件が変わる度に、最適な加熱条件を検討する必要があり、加熱装置の自動制御には程遠いと言わざるを得ない。また、温度帯の違う各加熱域を上流から下流に向けて並設する必要があるため、炉長を長くとらなければならず、大型の加熱装置が必要となる。 However, the heating method disclosed in Patent Document 1 simply involves setting the temperature and temperature rise time (conveyor speed) in each heating zone of the heating furnace. As a result, it is necessary to consider the optimal heating conditions each time the shape of the workpiece or other conditions change, and it must be said that this method is far from automatic control of the heating device. Furthermore, because each heating zone with a different temperature range needs to be installed side by side from upstream to downstream, the furnace must be long, necessitating a large heating device.
そこで、本発明の目的は、放射温度計を用いた加熱温度の自動制御が可能で、ワークを短時間且つ均一に加熱することのできる加熱装置及び加熱方法を提供することにある。 The object of the present invention is to provide a heating device and heating method that allows automatic control of the heating temperature using a radiation thermometer and can heat a workpiece uniformly and in a short time.
上記目的を達成するために、請求項１に記載の発明は、加熱装置であって、被加熱物を加熱するための赤外線ヒータと、赤外線ヒータの出力を制御する制御部と、被加熱物の表面温度を測定する放射温度計とを備え、赤外線ヒータは、近赤外線を放射し、被加熱物の表面温度が所定の目標温度になるまで被加熱物を昇温する第１の出力と、第１の出力より低出力で中赤外線から遠赤外線を放射し、被加熱物の内部温度が目標温度になるまで被加熱物の表面温度を維持する第２の出力との間で出力を任意に変更可能であり、第２の出力は、放射温度計によって計測される被加熱物の表面温度に応じて、制御部により制御されることを特徴とする。
請求項２に記載の発明は、上記構成において、放射温度計は、内部が赤外線吸収性を備える材料で塗装された輻射排除筒を備えることを特徴とする。
請求項３に記載の発明は、上記構成において、第１の出力は、赤外線ヒータに係る最大出力であることを特徴とする。
請求項４に記載の発明は、請求項１乃至３の何れかに記載の放射温度計を備える加熱装置を用いる加熱方法であって、被加熱物の表面温度が所定の目標温度になるまで、第１の出力の赤外線ヒータで被加熱物を昇温する加熱ターンと、第２の出力の赤外線ヒータで被加熱物の内部温度が目標温度になるまで被加熱物の表面温度を維持する保温ターンとを実行し、保温ターンにおいて、第２の出力を、放射温度計によって計測される被加熱物の表面温度に応じて、制御部により制御することを特徴とする。
In order to achieve the above object, the invention described in claim 1 is a heating device comprising an infrared heater for heating an object to be heated, a control unit for controlling the output of the infrared heater, and a radiation thermometer for measuring the surface temperature of the object to be heated, wherein the infrared heater is capable of arbitrarily changing its output between a first output that radiates near-infrared rays and heats the object until its surface temperature reaches a predetermined target temperature, and a second output that radiates mid-infrared to far-infrared rays at a lower output than the first output and maintains the surface temperature of the object until its internal temperature reaches the target temperature, and wherein the second output is controlled by the control unit in accordance with the surface temperature of the object to be heated measured by the radiation thermometer.
In accordance with a second aspect of the present invention, in the above-described configuration, the radiation thermometer includes a radiation excluding cylinder the inside of which is coated with a material having infrared absorbing properties.
According to a third aspect of the present invention, in the above-described configuration, the first output is a maximum output related to the infrared heater.
The invention described in claim 4 is a heating method using a heating device equipped with a radiation thermometer described in any one of claims 1 to 3, characterized in that a heating turn is performed in which an infrared heater with a first output heats up the object to be heated until the surface temperature of the object reaches a predetermined target temperature, and a heat retention turn is performed in which an infrared heater with a second output maintains the surface temperature of the object to be heated until the internal temperature of the object reaches the target temperature, and in the heat retention turn, the second output is controlled by a control unit in accordance with the surface temperature of the object to be heated measured by the radiation thermometer.
本発明の主な効果は、放射温度計を用いた加熱温度の自動制御が可能で、ワークを短時間且つ均一に加熱することのできる放射温度計を備える加熱装置及び加熱方法が提供されることである。 The main advantage of the present invention is that it provides a heating device and heating method equipped with a radiation thermometer that allows automatic control of the heating temperature using a radiation thermometer and can heat the workpiece uniformly in a short time.
以下、本発明の実施の形態を図面に基づいて説明する。
図１は、本発明の加熱装置を示す説明図であって、（ａ）は平面図、（ｂ）は（ａ）のＡ－Ａ線断面図である。
加熱装置１は、図１（ａ），（ｂ）に示すように、複数の直管型の赤外線ヒータ２と、被加熱物であるＣＦＲＰ等のワークＷを積載可能で、加熱装置１内を所定方向に向けて進行する移動式のステージ３と、ワークＷの表面温度を測定するための放射温度計４と、赤外線ヒータ２の出力を制御する制御部５とを備える。
本実施例において、ステージ３は、加熱装置１の対向する２辺に沿って設置された２本のレールＲ上を移動するものであり、その際のステージ３の移動機構は、公知の移動機構が適用される。
制御部５は、各赤外線ヒータ２それぞれに個別接続され、それぞれの赤外線ヒータ２を個別に制御するものでも良いし、全赤外線ヒータ２を一律に制御するものでも良い。また、制御部５は、放射温度計４とも接続しており、放射温度計４によって計測された温度に応じて赤外線ヒータ２の出力を調整可能となっている。なお、赤外線ヒータ２の出力は、停止状態である０％と最大出力である１００％との間の任意の値で調節可能である。
ワークＷは、加熱装置１によって加熱されることで、潜在応力を解消したり、加熱後にプレス成形等による変形加工、積層複合化等の加工が施されたりする。
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory diagram showing a heating device of the present invention, where (a) is a plan view and (b) is a cross-sectional view taken along line AA of (a).
As shown in Figures 1(a) and 1(b), the heating device 1 includes a plurality of straight tube infrared heaters 2, a movable stage 3 on which a workpiece W such as CFRP to be heated can be loaded and which moves in a predetermined direction within the heating device 1, a radiation thermometer 4 for measuring the surface temperature of the workpiece W, and a control unit 5 for controlling the output of the infrared heaters 2.
In this embodiment, the stage 3 moves on two rails R installed along two opposing sides of the heating device 1, and a known movement mechanism is used as the movement mechanism for the stage 3.
The control unit 5 may be connected to each infrared heater 2 individually and control each infrared heater 2 individually, or may be connected to all infrared heaters 2 uniformly. The control unit 5 is also connected to the radiation thermometer 4 and is capable of adjusting the output of the infrared heater 2 in accordance with the temperature measured by the radiation thermometer 4. The output of the infrared heater 2 can be adjusted to any value between 0%, which is the stopped state, and 100%, which is the maximum output.
The workpiece W is heated by the heating device 1 to eliminate latent stress, and after heating, is subjected to deformation processing such as press molding, lamination and other processing.
赤外線ヒータ２は、図１（ｂ）に示すように、ステージ３を上下に挟んで、上ヒータユニット２ａと下ヒータユニット２ｂとに配置される。上ヒータ２ａの上方及び下ヒータ２ｂの下方には、加熱効率を向上させるため、反射ユニット６が設けられている。さらに、反射ユニット６の上方及び下方には、加熱装置１の外部に伝熱することを防止するための断熱材７が配置されている。上ヒータ２ａ及び下ヒータ２ｂを設けることで、ワークＷを上下方向両側から同時に加熱できるため、ワークＷの上面及び下面に極端な温度差を生じさせずに、ワークＷを加熱することができる。 As shown in FIG. 1(b), the infrared heaters 2 are arranged in an upper heater unit 2a and a lower heater unit 2b, sandwiching the stage 3 from above and below. Reflection units 6 are provided above the upper heater 2a and below the lower heater 2b to improve heating efficiency. Furthermore, heat insulating materials 7 are provided above and below the reflection units 6 to prevent heat transfer to the outside of the heating device 1. By providing the upper heater 2a and the lower heater 2b, the workpiece W can be heated simultaneously from both above and below, allowing the workpiece W to be heated without causing extreme temperature differences between the top and bottom surfaces of the workpiece W.
図２は、本発明の放射温度計を示す説明図である。
放射温度計４は、図２に示すように、検出器４ａ、レンズ４ｂ、及び所定長さを有する円筒状の輻射排除筒８を備える。
放射温度計４は、計測対象であるワークＷの表面から放射された赤外線をレンズ４ｂを介して検出器４ａにて検出し、電気信号に変換することで、ワークＷの表面温度を測定するものである。輻射排除筒８は、内側が赤外線吸収性を備える黒色塗料によって塗装されている。輻射排除筒８に進入した赤外線は、黒色塗料に吸収されながら進むため、上ヒータユニット２ａと下ヒータユニット２ｂとの間における赤外線の散乱光の影響が抑えられ、放射温度計４によるワークＷの表面温度のより正確な測定が可能となる。なお、輻射排除筒８は、レンズ４ｂへの輻射光（赤外線）の入射を妨げない形状に形成されることが望ましい。輻射排除筒８の径は、大きすぎる場合、レンズ４ｂに入射される散乱光が多くなり、測定精度が低下する可能性がある。一方、輻射排除筒８の径が小さすぎる場合は、レンズ４ｂに入射される輻射光が少なくなるため、測定精度が低下する可能性がある。また、輻射排除筒８は、図１（ｂ）に示すように、赤外線ヒータ２（上ヒータユニット２ａ）とワークＷとの間に先端部が配置される長さを有する。これにより、上ヒータユニット２ａから放射される散乱光の輻射排除筒８へ進入を抑えられる。すなわち、適切な径と適正な長さとを有する形状の輻射排除筒８を用いることで、より正確な放射温度計４によるワークＷの表面温度の測定が可能となる。
FIG. 2 is an explanatory diagram showing the radiation thermometer of the present invention.
As shown in FIG. 2, the radiation thermometer 4 includes a detector 4a, a lens 4b, and a cylindrical radiation excluding tube 8 having a predetermined length.
The radiation thermometer 4 measures the surface temperature of the workpiece W by detecting infrared rays radiated from the surface of the workpiece W via the lens 4b using the detector 4a and converting the infrared rays into an electrical signal. The inside of the radiation exclusion tube 8 is painted with a black paint that is infrared-absorbing. Since the infrared rays that enter the radiation exclusion tube 8 are absorbed by the black paint, the influence of scattered infrared light between the upper heater unit 2a and the lower heater unit 2b is suppressed, enabling more accurate measurement of the surface temperature of the workpiece W using the radiation thermometer 4. It is desirable that the radiation exclusion tube 8 be formed in a shape that does not prevent radiant light (infrared rays) from entering the lens 4b. If the diameter of the radiation exclusion tube 8 is too large, more scattered light will be incident on the lens 4b, potentially reducing measurement accuracy. On the other hand, if the diameter of the radiation exclusion tube 8 is too small, less radiant light will be incident on the lens 4b, potentially reducing measurement accuracy. 1(b), the radiation exclusion cylinder 8 has a length that allows its tip to be positioned between the infrared heater 2 (upper heater unit 2a) and the workpiece W. This prevents scattered light emitted from the upper heater unit 2a from entering the radiation exclusion cylinder 8. In other words, by using a radiation exclusion cylinder 8 having a shape with an appropriate diameter and an appropriate length, it becomes possible to more accurately measure the surface temperature of the workpiece W using the radiation thermometer 4.
続いて、加熱装置１を用いたワークＷの加熱方法について説明する。
図３は、加熱工程における赤外線ヒータの出力、並びにワークの表面及び断面中心温度の推移イメージを示すグラフである。
まず、ワークＷをステージ３上に載置した後、ステージ３を移動させる。ステージ３の移動に伴い、ワークＷは加熱装置１の内部に移動する。
ワークＷが加熱装置１の内部に移動した後、図３に示すように、制御部５は、ワークＷの表面温度が所定の目標温度となるように第１の出力（ここでは出力１００％）で赤外線ヒータ２によるワークＷの急速加熱を実行する（加熱ターンＨ）。加熱ターンＨでは、高出力の近赤外線が赤外線ヒータ２から放射される。高出力で表面から加熱されるため、ワークＷの内部温度は目標温度より低い。近赤外線の波長領域は、放射温度計４の測定領域と重複するため、加熱ターンＨでは、赤外線ヒータ２からの散乱光を放射温度計４が検出してしまい、ワークＷの表面温度の正確な測定ができない。そのため、加熱ターンＨでは、事前に確認した所定の温度パターンで、ワークＷを目標温度近辺まで短時間で急速昇温させる必要がある。本出願において、近赤外線とは、０．７μｍ～１．５μｍの波長領域の赤外線を指す。また、中赤外線とは、１．５μｍ～４．０μｍの波長領域の赤外線を指し、遠赤外線とは、４．０μｍ～１０００μｍの波長領域の赤外線を指す。
Next, a method for heating the workpiece W using the heating device 1 will be described.
FIG. 3 is a graph showing the output of the infrared heater and the transition of the temperatures on the surface and at the center of the cross section of the workpiece during the heating process.
First, the workpiece W is placed on the stage 3, and then the stage 3 is moved. As the stage 3 moves, the workpiece W moves into the heating device 1.
After the workpiece W is moved into the heating device 1, as shown in FIG. 3 , the control unit 5 rapidly heats the workpiece W using the infrared heater 2 at a first output (here, 100% output) so that the surface temperature of the workpiece W reaches a predetermined target temperature (heating turn H). In heating turn H, high-power near-infrared rays are emitted from the infrared heater 2. Because the workpiece W is heated from the surface at high output, the internal temperature of the workpiece W is lower than the target temperature. Because the wavelength range of near-infrared rays overlaps with the measurement range of the radiation thermometer 4, in heating turn H, the radiation thermometer 4 detects scattered light from the infrared heater 2, preventing accurate measurement of the surface temperature of the workpiece W. Therefore, in heating turn H, it is necessary to rapidly heat the workpiece W to near the target temperature in a short period of time using a predetermined temperature pattern confirmed in advance. In this application, near-infrared rays refer to infrared rays in the wavelength range of 0.7 μm to 1.5 μm. Furthermore, mid-infrared rays refer to infrared rays in the wavelength region of 1.5 μm to 4.0 μm, and far-infrared rays refer to infrared rays in the wavelength region of 4.0 μm to 1000 μm.
ワークＷの表面温度が目標温度近辺に達した後、制御部５は、赤外線ヒータ２の出力を第２の出力（ここでは出力１０％）に変更する。そして、ワークＷの表面温度を目標温度近辺で維持した状態で、ワークＷの内部温度を目標温度近辺まで昇温させる（保温ターンＫ）。保温ターンＫでは、低出力の赤外線、即ち中赤外線から遠赤外線が赤外線ヒータ２から放射される。中赤外線から遠赤外線の波長領域は、放射温度計４の測定領域と重複していない。従って、放射温度計４を用いたワークＷの所定精度以上の表面温度測定が可能となる。また、このとき、一定の散乱光による測定誤差が生じることが考えられるが、放射温度計４に輻射排除筒８を設けたことで、輻射排除筒８が散乱光を吸収するため、散乱光による測定誤差をほぼ抑え、ワークＷの表面からの赤外線に測定対象が絞られ、ワークＷの正確な温度測定（輻射率０．９～０．９５の通常の設定値での測定）が可能となる。放射温度計４によりワークＷの正確な表面温度測定が可能となったことで、保温ターンＫでは、制御部５は、測定された温度に応じて、赤外線ヒータ２の出力を自動で制御している。これにより、加熱装置１は、ワークＷの表面温度を保ちつつ、ワークＷの内部温度が目標温度となるまで適切な加熱処理を実行する。
このように、加熱ターンＨと保温ターンＫとを赤外線ヒータ２の出力変更により実行することで、長い炉長を必要とする大型の従来型の加熱装置と比べ、加熱装置１を小型に設計できる。
また、保温ターンＫでは、赤外線ヒータ２の出力を絞り、放射される赤外線を中赤外線から遠赤外線とすると共に、放射温度計４に輻射排除筒８を設けることで、放射温度計４によるワークＷの正確な表面温度測定が可能となるため、測定された温度を基に、制御部５による赤外線ヒータ２の出力、即ち加熱温度の自動制御が可能となる。これにより、ワークＷの表面温度が目標温度から離れることを防止しながら、ワークＷの内部温度が目標温度となるまで適切に加熱することができる。
After the surface temperature of the workpiece W reaches near the target temperature, the control unit 5 changes the output of the infrared heater 2 to a second output (10% output in this example). Then, while maintaining the surface temperature of the workpiece W near the target temperature, the internal temperature of the workpiece W is raised to near the target temperature (heat retention turn K). In heat retention turn K, low-power infrared rays, i.e., mid-infrared to far-infrared rays, are emitted from the infrared heater 2. The wavelength range of mid-infrared to far-infrared rays does not overlap with the measurement range of the radiation thermometer 4. Therefore, it is possible to measure the surface temperature of the workpiece W with a predetermined accuracy or higher using the radiation thermometer 4. Furthermore, while it is conceivable that a certain amount of measurement error may occur due to scattered light, the radiation exclusion tube 8 provided in the radiation thermometer 4 absorbs the scattered light, thereby almost completely suppressing measurement errors due to scattered light and narrowing the measurement target to infrared rays from the surface of the workpiece W, enabling accurate temperature measurement of the workpiece W (measurement at a normal emissivity setting of 0.9 to 0.95). Since the radiation thermometer 4 makes it possible to accurately measure the surface temperature of the workpiece W, in the heat retention turn K, the control unit 5 automatically controls the output of the infrared heater 2 according to the measured temperature. As a result, the heating device 1 performs an appropriate heating process until the internal temperature of the workpiece W reaches the target temperature while maintaining the surface temperature of the workpiece W.
In this way, by performing the heating turn H and the heat retention turn K by changing the output of the infrared heater 2, the heating device 1 can be designed to be smaller than large conventional heating devices that require a long furnace length.
Furthermore, in the heat retention turn K, the output of the infrared heater 2 is reduced, the infrared rays emitted are changed from mid-infrared to far-infrared, and a radiation exclusion tube 8 is provided on the radiation thermometer 4, which enables accurate measurement of the surface temperature of the workpiece W by the radiation thermometer 4, and therefore enables automatic control of the output of the infrared heater 2, i.e., the heating temperature, by the control unit 5 based on the measured temperature. This makes it possible to properly heat the workpiece W until its internal temperature reaches the target temperature, while preventing the surface temperature of the workpiece W from deviating from the target temperature.
次に、本発明の加熱装置１を用いた加熱試験の結果を示す。
図４は、加熱試験結果を示すグラフである。
加熱試験では、加熱装置１を用い、厚み４ｍｍで１００ｍｍ四方のＣＦＲＰからなるワークＷを３０秒間加熱し、ワーク中央の表面及び内部、ワーク中央から３０ｍｍ地点の表面及び内部、ワーク中央から４５ｍｍ地点の表面及び内部の各計測点における温度計測を行った。なお、ワークＷの表面及び内部の各測定点における温度計測は、熱電対を用いて行った。内部温度は、表面からの深度２ｍｍの箇所での温度である。
Next, the results of a heating test using the heating device 1 of the present invention will be shown.
FIG. 4 is a graph showing the results of the heating test.
In the heating test, a workpiece W made of CFRP with a thickness of 4 mm and a size of 100 mm square was heated for 30 seconds using the heating device 1, and temperatures were measured at the surface and interior at the center of the workpiece, the surface and interior at a point 30 mm from the center of the workpiece, and the surface and interior at a point 45 mm from the center of the workpiece. The temperature measurements at each measurement point on the surface and interior of the workpiece W were performed using thermocouples. The internal temperature was the temperature at a point 2 mm deep from the surface.
加熱試験の結果を図４に示す。図４のグラフは、上述の各計測点において測定された測定温度に加え、電力（赤外線ヒータ２の出力）、放射温度計４が検出したワークＷの表面温度の推移を示している。なお、放射温度計４は、ワーク中央の表面温度を計測した。
まず、加熱ターンＨとして、電力を９０ｋＷ（赤外線ヒータ２の出力は１００％であり、これが第１の出力となる。）とし、ワークＷの表面温度が目標温度である２００℃となるまで加熱を行った。
時間経過と共に、ワークＷの表面温度は、ワークＷの中央、中央から３０ｍｍ地点、中央から４５ｍｍ地点の何れにおいても、加熱開始からほぼ一様に温度が急速に上昇し、およそ１０秒で目標温度に達した。一方、ワークＷの各部における内部温度は、１０秒経過時点でも１２０℃程度であり、ワークＷの表面温度とは大きな差があることが分かる。
また、この時、赤外線ヒータ２からの散乱光により放射温度計４は、正確な温度計測ができていないことが分かる。
The results of the heating test are shown in Figure 4. The graph in Figure 4 shows the measured temperatures at each of the above-mentioned measurement points, as well as the changes in power (output of the infrared heater 2) and the surface temperature of the workpiece W detected by the radiation thermometer 4. The radiation thermometer 4 measured the surface temperature at the center of the workpiece.
First, in the heating turn H, the power was set to 90 kW (the output of the infrared heater 2 was 100%, which was the first output), and the workpiece W was heated until its surface temperature reached the target temperature of 200°C.
As time passed, the surface temperature of the workpiece W rose rapidly and almost uniformly from the start of heating at the center, 30 mm from the center, and 45 mm from the center of the workpiece W, reaching the target temperature in about 10 seconds. On the other hand, the internal temperature of each part of the workpiece W was about 120°C even after 10 seconds had passed, which is clearly a large difference from the surface temperature of the workpiece W.
At this time, it is also found that the radiation thermometer 4 is unable to measure the temperature accurately due to scattered light from the infrared heater 2.
ワークＷの表面温度が目標温度に達した後、保温ターンＫに切替え、電力をおよそ１０ｋＷ（赤外線ヒータ２の出力はおよそ１０％であり、これが第２の出力となる）に絞り、ワークＷの内部温度が目標温度である２００℃となるまで加熱を行った。
なお、保温ターンＫにおいて、電力は制御部５によって微調整される。オーバーシュートしていたワークＷの表面温度が目標温度に向け変移していくのに併せて、ワークＷの内部温度が緩やかに上昇し、加熱開始からおよそ３０秒で、ワークＷの表面温度及び内部温度の何れもが全計測点において目標温度となった。
このように、加熱ターンＨ及び保温ターンＫを実行することで、３０秒という短時間でも４ｍｍの厚物を均一加熱することができる。
また、この時、放射温度計４は、赤外線ヒータ２の出力が１０％程度に近づくにつれ、ワークＷの表面温度を正確に測定できていることが分かる。これは、赤外線ヒータ２の出力を絞ったことで、放射温度計４の測定領域と重複していない中赤外線から遠赤外線が赤外線ヒータ２から放射されるようになり、散乱光を放射温度計４に輻射排除筒８で排除したことで、放射温度計４によるワークＷの表面温度の正確な測定が可能となったことが分かる。
After the surface temperature of the workpiece W reached the target temperature, the heat retention turn K was switched on, the power was reduced to approximately 10 kW (the output of the infrared heater 2 was approximately 10%, which became the second output), and the workpiece W was heated until its internal temperature reached the target temperature of 200°C.
In the heat retention turn K, the power is finely adjusted by the control unit 5. As the surface temperature of the workpiece W, which had been overshooting, transitions toward the target temperature, the internal temperature of the workpiece W gradually rises, and approximately 30 seconds after the start of heating, both the surface temperature and the internal temperature of the workpiece W reached the target temperature at all measurement points.
In this way, by performing the heating turn H and the heat retention turn K, it is possible to uniformly heat a 4 mm thick object even in a short time of 30 seconds.
It can also be seen that at this time, as the output of the infrared heater 2 approaches approximately 10%, the radiation thermometer 4 is able to accurately measure the surface temperature of the workpiece W. This is because, by reducing the output of the infrared heater 2, mid-infrared to far-infrared rays that do not overlap with the measurement area of the radiation thermometer 4 are emitted from the infrared heater 2, and scattered light is excluded from the radiation thermometer 4 by the radiation exclusion tube 8, making it possible for the radiation thermometer 4 to accurately measure the surface temperature of the workpiece W.
図５は、熱電対を用いて測定されたワーク表面温度と放射温度計を用いて測定されたワーク表面温度との差と、赤外線ヒータの出力との関係を示すグラフである。
図５に、熱電対を用いて測定されたワークＷの表面温度と放射温度計４を用いて測定されたワークＷの表面温度との差と、赤外線ヒータ２の出力との関係をグラフ化して示す。
赤外線ヒータ２の出力が１００％、すなわち第１の出力の場合、熱電対を用いて測定されたワークＷの表面温度と放射温度計４を用いて測定されたワークＷの表面温度との差は、およそΔ６０℃となった。従って、第１の出力の場合、放射温度計４はワークＷの表面温度を正確に測定できていないことが分かる。
赤外線ヒータ２の出力を５０％とすると、熱電対を用いて測定されたワークＷの表面温度と放射温度計４を用いて測定されたワークＷの表面温度との差は、およそΔ２０℃となった。
さらに赤外線ヒータ２の出力を絞り、出力を１０％、すなわち第２の出力とした場合、熱電対を用いて測定されたワークＷの表面温度と放射温度計４を用いて測定されたワークＷの表面温度との差は、ほぼΔ０℃となった。従って、第２の出力とした場合、放射温度計４は、ワークＷの表面温度を正確に測定できる。
FIG. 5 is a graph showing the relationship between the difference between the workpiece surface temperature measured using a thermocouple and the workpiece surface temperature measured using a radiation thermometer, and the output of the infrared heater.
FIG. 5 is a graph showing the relationship between the difference between the surface temperature of the workpiece W measured using a thermocouple and the surface temperature of the workpiece W measured using the radiation thermometer 4 and the output of the infrared heater 2.
When the output of the infrared heater 2 is 100%, i.e., the first output, the difference between the surface temperature of the workpiece W measured using the thermocouple and the surface temperature of the workpiece W measured using the radiation thermometer 4 is approximately Δ60° C. Therefore, it can be seen that, when the output is the first output, the radiation thermometer 4 is unable to accurately measure the surface temperature of the workpiece W.
When the output of the infrared heater 2 was set to 50%, the difference between the surface temperature of the workpiece W measured using the thermocouple and the surface temperature of the workpiece W measured using the radiation thermometer 4 was approximately Δ20°C.
Furthermore, when the output of the infrared heater 2 is reduced to 10%, i.e., set to the second output, the difference between the surface temperature of the workpiece W measured using the thermocouple and the surface temperature of the workpiece W measured using the radiation thermometer 4 is approximately Δ0°C. Therefore, when set to the second output, the radiation thermometer 4 can accurately measure the surface temperature of the workpiece W.
上述のように構成される加熱装置１は、ワークＷを加熱するための赤外線ヒータ２と、赤外線ヒータ２の出力を制御する制御部５と、ワークＷの表面温度を測定する放射温度計４とを備え、赤外線ヒータ２は、ワークＷの表面温度が所定の目標温度になるまでワークＷを急速に昇温する第１の出力と、第１の出力より低出力で中赤外線から遠赤外線を放射し、ワークＷの内部温度が目標温度になるまでワークＷの表面温度を維持する第２の出力との間で出力を任意に変更可能であり、第２の出力は、放射温度計４によって計測されるワークＷの表面温度に応じて、制御部５により制御される。
よって、加熱装置１は、赤外線ヒータ２の出力を変更可能とすることで、長い炉長を必要とする大型の従来型の加熱装置と比べ、加熱装置１を小型に設計できる。
また、赤外線ヒータ２の出力を絞り、放射される赤外線を中赤外線から遠赤外線とすることで、放射温度計４によるワークＷの表面温度測定が可能となるため、測定された温度を基に、制御部５による赤外線ヒータ２の出力、即ち加熱温度の自動制御が可能となる。これにより、ワークＷの表面温度が目標温度から離れることを防止しながら、ワークＷの内部温度が目標温度となるまで適切に加熱することができる。
The heating device 1 configured as described above comprises an infrared heater 2 for heating the workpiece W, a control unit 5 for controlling the output of the infrared heater 2, and a radiation thermometer 4 for measuring the surface temperature of the workpiece W, and the infrared heater 2 is capable of arbitrarily changing its output between a first output that rapidly heats the workpiece W until the surface temperature of the workpiece W reaches a predetermined target temperature, and a second output that radiates mid-infrared to far-infrared rays at a lower output than the first output and maintains the surface temperature of the workpiece W until the internal temperature of the workpiece W reaches the target temperature, and the second output is controlled by the control unit 5 in accordance with the surface temperature of the workpiece W measured by the radiation thermometer 4.
Therefore, by making the output of the infrared heater 2 variable, the heating device 1 can be designed to be smaller than large conventional heating devices that require a long furnace length.
Furthermore, by reducing the output of the infrared heater 2 and changing the infrared rays emitted from mid-infrared to far-infrared, it becomes possible to measure the surface temperature of the workpiece W using the radiation thermometer 4, and based on the measured temperature, the output of the infrared heater 2, i.e., the heating temperature, can be automatically controlled by the control unit 5. This makes it possible to properly heat the workpiece W until its internal temperature reaches the target temperature, while preventing the surface temperature of the workpiece W from deviating from the target temperature.
また、放射温度計は、内部が赤外線吸収性を備える材料で塗装された輻射排除筒を備える。
よって、輻射排除筒８に進入した赤外線は、黒色塗料に吸収されながら進むため、ワークＷの表面から放射される赤外線の散乱光の影響が抑えられ、放射温度計４によるワークＷの表面温度のより正確な測定が可能となる。
The radiation thermometer also includes a radiation excluding tube the inside of which is coated with an infrared absorbing material.
Therefore, the infrared rays that enter the radiation exclusion tube 8 are absorbed by the black paint as they travel, thereby reducing the influence of scattered light from the infrared rays emitted from the surface of the workpiece W, and enabling more accurate measurement of the surface temperature of the workpiece W using the radiation thermometer 4.
以上は、本発明を図示例に基づいて説明したものであり、その技術範囲はこれに限定されるものではない。例えば、第１の出力及び第２の出力は、被加熱物を目標温度に所望の時間で加熱可能であれば、任意に設定可能である。
また、赤外線ヒータは、被加熱物を加熱可能であれば、形状及び設置数は限定されず、任意の形状及び設置数で良い。さらに、被加熱物の上方のみ又は下方のみに設置されても良い。
また、放射温度計は、複数設けられても良いし、設置位置も限定されない。
また、輻射排除筒は、被加熱物の表面温度が正確に測定可能であれば、長さ、形状等を任意に設計できる。
また、制御部は、赤外線ヒータの出力変更ができれば良く、自動で赤外線ヒータの出力を制御するものとしても、制御部を介して人為的に赤外線ヒータの出力を変更するものとしても良い。
また、ステージは、レール上を周知の駆動機構によって移動するものに限定されず、例えばステージ自体がベルトコンベアで形成されても良い。
また、加熱装置は、第１の出力の赤外線ヒータで被加熱物の表面を目標温度まで加熱する加熱エリアと、制御部によって第２の出力を調整しながら被加熱物の内部まで目標温度で均一に加熱する保温エリアとが設けられ、加熱エリアから保温エリアへ被加熱物が載置されたステージが移動することで、被加熱物を加熱するものであっても良い。
また、被加熱物の加熱は、被加熱物を加熱するために中赤外線から遠赤外線を放射する赤外線ヒータと、赤外線ヒータの出力を制御する制御部と、内部が赤外線吸収性を備える材料で塗装された輻射排除筒を有し、被加熱物の表面温度を測定する放射温度計とを備える加熱装置を用いて、被加熱物の表面温度及び内部温度が所定の目標温度になるまで、赤外線ヒータの出力を、放射温度計によって計測される被加熱物の表面温度に応じて、制御部により制御しながら実施されても良い。
The present invention has been described above based on the illustrated examples, and the technical scope of the present invention is not limited to these. For example, the first output and the second output can be set arbitrarily as long as the object to be heated can be heated to the target temperature in a desired time.
Furthermore, the shape and number of infrared heaters to be installed are not limited as long as they can heat the object to be heated. Furthermore, the infrared heaters may be installed only above or only below the object to be heated.
Furthermore, multiple radiation thermometers may be provided, and the installation locations are not limited.
Furthermore, the radiation exclusion cylinder can be designed to have any length, shape, etc., as long as the surface temperature of the object to be heated can be measured accurately.
Furthermore, the control unit may be configured to automatically control the output of the infrared heater, or may manually change the output of the infrared heater via the control unit, as long as it can change the output of the infrared heater.
Furthermore, the stage is not limited to one that moves on rails by a known drive mechanism, and the stage itself may be formed of a belt conveyor, for example.
The heating device may also be provided with a heating area in which the surface of the heated object is heated to a target temperature using an infrared heater with a first output, and a heat retention area in which the inside of the heated object is uniformly heated to the target temperature while a control unit adjusts the second output, and the heated object is heated by moving a stage on which the heated object is placed from the heating area to the heat retention area.
In addition, the heating of the object to be heated may be carried out using a heating device comprising an infrared heater that emits mid-infrared to far-infrared rays to heat the object to be heated, a control unit that controls the output of the infrared heater, and a radiation thermometer that has a radiation exclusion tube the inside of which is painted with an infrared-absorbing material and measures the surface temperature of the object to be heated, with the output of the infrared heater being controlled by the control unit in accordance with the surface temperature of the object to be heated measured by the radiation thermometer until the surface temperature and internal temperature of the object to be heated reach a predetermined target temperature.
１・・加熱装置、２・・赤外線ヒータ、４・・放射温度計、５・・制御部、８・・輻射排除筒、Ｗ・・ワーク（被加熱物）。 1. Heating device, 2. Infrared heater, 4. Radiation thermometer, 5. Control unit, 8. Radiation exclusion tube, W. Work (object to be heated).
Claims (4)
前記赤外線ヒータは、近赤外線を放射し、前記被加熱物の表面温度が所定の目標温度になるまで前記被加熱物を昇温する第１の出力と、第１の出力より低出力で中赤外線から遠赤外線を放射し、前記被加熱物の内部温度が前記目標温度になるまで前記被加熱物の表面温度を維持する第２の出力との間で出力を任意に変更可能であり、
前記第２の出力は、前記放射温度計によって計測される前記被加熱物の表面温度に応じて、前記制御部により制御されることを特徴とする加熱装置。 The heating device includes an infrared heater for heating an object to be heated, a control unit for controlling the output of the infrared heater, and a radiation thermometer for measuring the surface temperature of the object to be heated,
the infrared heater is capable of arbitrarily changing its output between a first output that radiates near-infrared rays and heats the object until the surface temperature of the object reaches a predetermined target temperature, and a second output that radiates mid-infrared rays to far-infrared rays at an output lower than the first output and maintains the surface temperature of the object until the internal temperature of the object reaches the target temperature;
The heating device is characterized in that the second output is controlled by the control unit in accordance with the surface temperature of the object to be heated measured by the radiation thermometer.
前記被加熱物の表面温度が所定の目標温度になるまで、前記第１の出力の前記赤外線ヒータで前記被加熱物を昇温する加熱ターンと、
前記第２の出力の前記赤外線ヒータで前記被加熱物の内部温度が前記目標温度になるまで前記被加熱物の表面温度を維持する保温ターンとを実行し、
前記保温ターンにおいて、前記第２の出力を、前記放射温度計によって計測される前記被加熱物の表面温度に応じて、前記制御部により制御することを特徴とする加熱方法。 Using the heating device according to any one of claims 1 to 3,
a heating cycle in which the temperature of the object to be heated is increased by the infrared heater with the first output until the surface temperature of the object to be heated reaches a predetermined target temperature;
a heat retention cycle in which the surface temperature of the object to be heated is maintained by the infrared heater of the second output until the internal temperature of the object to be heated reaches the target temperature;
A heating method characterized in that, in the heat retention turn, the second output is controlled by the control unit in accordance with the surface temperature of the heated object measured by the radiation thermometer.
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| JP2019188770A (en) | 2018-04-27 | 2019-10-31 | 中部電力株式会社 | Resin or resin composite material heater and method |
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