JP2005225704A - Method of extending glass base material - Google Patents

Method of extending glass base material Download PDF

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JP2005225704A
JP2005225704A JP2004035115A JP2004035115A JP2005225704A JP 2005225704 A JP2005225704 A JP 2005225704A JP 2004035115 A JP2004035115 A JP 2004035115A JP 2004035115 A JP2004035115 A JP 2004035115A JP 2005225704 A JP2005225704 A JP 2005225704A
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base material
glass base
load
temperature
stretching
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JP4224705B2 (en
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Kiichiro Kawasaki
希一郎 川崎
Sumio Hoshino
寿美夫 星野
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Sumitomo Electric Industries Ltd
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Sumitomo Electric Industries Ltd
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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
    • C03B37/01225—Means for changing or stabilising the shape, e.g. diameter, of tubes or rods in general, e.g. collapsing
    • C03B37/0126—Means for supporting, rotating, translating the rod, tube or preform
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
    • C03B37/01225—Means for changing or stabilising the shape, e.g. diameter, of tubes or rods in general, e.g. collapsing
    • C03B37/0124—Means for reducing the diameter of rods or tubes by drawing, e.g. for preform draw-down
    • C03B37/01242—Controlling or regulating the down-draw process

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacture, Treatment Of Glass Fibers (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the load to be applied to a part for grasping a glass base material at the time of starting the extension of the glass base material. <P>SOLUTION: In this method of extending the glass base material, a glass base material G is arranged in a heating furnace 2, the glass base material is heated, and the load supporting the glass base material G is measured with a load measuring device 10 fixed to an upper part chuck 3, and after the measured force becomes a specified value over a specified time t1, the extension of the glass base material is performed. And, when the glass base material is arranged in the heating furnace 2, the temperature of a core pipe 5 is preliminarily made to be at a temperature lower than the extension temperature. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、ガラス母材を加熱して延伸する方法に関する。   The present invention relates to a method for heating and stretching a glass base material.

従来、ガラス母材を加熱炉内で加熱して延伸する際には、ガラス母材を加熱炉内に配置する前、あるいは、ガラス母材を加熱炉内に配置するときに、加熱炉のヒータをガラス母材の延伸を行う温度まで昇温させていた。そして、ガラス母材を所定の位置に配置させた直後に、ガラス母材を把持する送り側と引取り側のチャックを相対移動させてガラス母材に張力をかけ、延伸を開始していた。   Conventionally, when a glass base material is heated and stretched in a heating furnace, before the glass base material is placed in the heating furnace or when the glass base material is placed in the heating furnace, the heater of the heating furnace Was heated to a temperature at which the glass base material was stretched. Immediately after placing the glass base material at a predetermined position, the feeding side and the take-up side chucks for gripping the glass base material are moved relative to each other to apply tension to the glass base material and start stretching.

また、母材インゴットをこれより小径の母材ロッドに延伸して光ファイバ母材を製造する方法において、母材インゴットの引取りを開始するまでに、引取り側においてロッドに張力を与えたときの伸びを測定することにより、母材インゴットの引取り開始時期を決定することが知られている（例えば、特許文献１参照。）。特許文献１に記載された延伸方法によれば、延伸後の光ファイバ母材の曲がりを低減化することができるとされている。   Also, in the method of manufacturing an optical fiber preform by drawing a preform ingot to a smaller-diameter preform rod, when the rod is tensioned on the take-up side before the take-up of the preform ingot is started. It is known to determine the start time of taking the base material ingot by measuring the elongation of the base material (see, for example, Patent Document 1). According to the stretching method described in Patent Document 1, it is said that the bending of the optical fiber preform after stretching can be reduced.

特許第３１５１３６７号公報Japanese Patent No. 3151367

ところで、ヒータの温度が延伸を行う温度に達しても、ガラス母材（母材インゴット）がその内部まで十分に加熱されるまでには、ある程度の時間を要する。そのため、上記の延伸方法では、ガラス母材が十分に軟化しないまま延伸が開始され、ガラス母材を把持する部分に過大な荷重がかかってしまうことがあった。   By the way, even if the temperature of the heater reaches the temperature at which stretching is performed, a certain amount of time is required until the glass base material (base material ingot) is sufficiently heated to the inside. For this reason, in the above-described stretching method, stretching is started without sufficiently softening the glass base material, and an excessive load may be applied to a portion that holds the glass base material.

そして、ガラス母材を把持するチャックに所定の値以上の荷重が加わると、延伸装置の安全装置が働いて、延伸装置の運転が停止してしまうことがあった。その場合には、延伸装置の稼働率が低下し、得られるガラス母材の生産性が低下してしまう。
また、ガラス母材が十分に軟化しないままガラス母材に大きな張力が加わると、ガラス母材の両端側に取り付けられた、ガラス母材を把持するためのダミー棒が損傷してしまうおそれもあった。ダミー棒が損傷してしまうと、安全に延伸作業を行うことが困難となるため、一旦ガラス母材を延伸装置から外して、損傷したダミー棒を再加工するか、あるいは交換しなければならなかった。 When a load of a predetermined value or more is applied to the chuck that grips the glass base material, the stretching device safety device may work, and the stretching device may stop operating. In that case, the operation rate of the drawing apparatus is lowered, and the productivity of the obtained glass base material is lowered.
In addition, if a large tension is applied to the glass base material without sufficiently softening the glass base material, the dummy rods for gripping the glass base material attached to both ends of the glass base material may be damaged. It was. If the dummy bar is damaged, it will be difficult to perform the drawing process safely, so the glass base material must be removed from the drawing device and the damaged dummy bar must be reworked or replaced. It was.

また、上記特許文献１に記載された延伸方法においても、まず引取り側のチャックから母材インゴットに張力を与えて、母材の伸び量を測定するため、チャックやダミー棒には過大な荷重がかかってしまうことが同様に想定される。   In the stretching method described in Patent Document 1 above, too much load is applied to the chuck or dummy bar because tension is applied to the base material ingot from the take-up side chuck and the base material ingot is measured. It is also assumed that it will be applied.

本発明は、延伸開始時にガラス母材を把持する部分にかかる負荷を低減することのできるガラス母材の延伸方法を提供することを目的としている。   An object of the present invention is to provide a method for stretching a glass base material that can reduce a load applied to a portion that holds the glass base material at the start of stretching.

上記課題を解決することのできる本発明に係るガラス母材の延伸方法は、加熱部を備えた加熱炉内にガラス母材を配置し、前記加熱部により前記ガラス母材を加熱して、前記ガラス母材を支持している荷重を測定し、加熱開始後に前記測定した荷重が所定の時間にわたり所定の値になった後、前記ガラス母材の延伸を開始するものである。   The glass base material stretching method according to the present invention that can solve the above-mentioned problem is that a glass base material is disposed in a heating furnace provided with a heating part, the glass base material is heated by the heating part, The load supporting the glass base material is measured, and after the measured load becomes a predetermined value over a predetermined time after the start of heating, the glass base material starts to be stretched.

また、本発明に係るガラス母材の延伸方法において、前記荷重は、前記ガラス母材をその両端を把持して垂直方向に配置し、その上端側で前記ガラス母材を支持している荷重であることが好ましい。   Further, in the glass base material stretching method according to the present invention, the load is a load in which the glass base material is gripped at both ends and arranged in the vertical direction, and the glass base material is supported on the upper end side. Preferably there is.

また、本発明に係るガラス母材の延伸方法において、前記加熱炉内に前記ガラス母材を配置した後、前記加熱部の温度を１７００℃以上に昇温させてから延伸を開始することが好ましい。なお、ガラス母材の延伸を良好に行うためにガラスを十分に軟化させる加熱部の温度が１７００℃以上であり、例えば好適な温度範囲は、１７００℃から１９００℃程度である。また、ここで挙げた加熱部の温度とは、ガラス母材を加熱するための部材（ヒータや炉心管等を含む）の内側表面の最高温度を基準としている。   In the glass base material stretching method according to the present invention, it is preferable that the glass base material is placed in the heating furnace, and then the temperature of the heating unit is raised to 1700 ° C. or higher before starting the stretching. . In addition, the temperature of the heating part that sufficiently softens the glass in order to satisfactorily stretch the glass base material is 1700 ° C. or higher. For example, a suitable temperature range is about 1700 ° C. to 1900 ° C. Moreover, the temperature of the heating part mentioned here is based on the maximum temperature of the inner surface of a member (including a heater and a core tube) for heating the glass base material.

また、本発明に係るガラス母材の延伸方法において、前記加熱炉内に前記ガラス母材を配置する際の前記加熱部の温度を１１００℃以下とすることが好ましい。   Moreover, in the extending | stretching method of the glass base material which concerns on this invention, it is preferable that the temperature of the said heating part at the time of arrange | positioning the said glass base material in the said heating furnace shall be 1100 degrees C or less.

本発明によれば、延伸開始時にガラス母材を把持する部分にかかる負荷を低減することができ、確実かつ安全性の高い延伸作業を行うことができる。   According to the present invention, it is possible to reduce a load applied to a portion that holds the glass base material at the start of stretching, and a reliable and highly safe stretching operation can be performed.

以下、本発明に係るガラス母材の延伸方法の実施の形態の例を、図面を参照して説明する。
図１に、本発明に係るガラス母材の延伸方法を実施することのできる延伸装置を示す。図１に示すように、本実施形態で用いられる延伸装置１は、ガラス母材Ｇを垂直に配置する縦型の延伸装置であり、ガラス母材Ｇを加熱する加熱炉２と、ガラス母材Ｇに接続されたダミー棒Ｇ１，Ｇ２を把持する上部チャック３及び下部チャック４を備えている。上部チャック３は加熱炉２の上側に配置され、下部チャック４は加熱炉２の下側に配置されている。 Hereinafter, an example of an embodiment of a glass base material stretching method according to the present invention will be described with reference to the drawings.
In FIG. 1, the extending | stretching apparatus which can implement the extending | stretching method of the glass base material which concerns on this invention is shown. As shown in FIG. 1, a stretching apparatus 1 used in the present embodiment is a vertical stretching apparatus that vertically arranges a glass base material G, a heating furnace 2 that heats the glass base material G, and a glass base material. An upper chuck 3 and a lower chuck 4 for holding dummy rods G1 and G2 connected to G are provided. The upper chuck 3 is disposed on the upper side of the heating furnace 2, and the lower chuck 4 is disposed on the lower side of the heating furnace 2.

加熱炉２には、ガラス母材Ｇを加熱するための円筒状の炉心管５が設けられ、炉心管５の外周側には円筒状のヒータ６が設けられている。これらの炉心管５とヒータ６により、加熱炉２の加熱部が構成されている。炉心管５及びヒータ６は、カーボンで形成されている。特に、炉心管５及びヒータ６は、ガラス母材Ｇに不純物を付着させることを防止するために、高純度カーボンであることが好ましい。
ヒータ６は、通電させることで抵抗加熱することができ、炉心管５は、ヒータ６により加熱されて昇温する。但し、ヒータ６は誘導加熱方式で発熱させても良い。
さらに、加熱炉２は、ガラス母材Ｇを配置する加熱炉２の内側の空間に窒素等の不活性ガスを導入できるように構成されている。 A cylindrical furnace core tube 5 for heating the glass base material G is provided in the heating furnace 2, and a cylindrical heater 6 is provided on the outer peripheral side of the furnace core tube 5. The furnace tube 5 and the heater 6 constitute a heating section of the heating furnace 2. The core tube 5 and the heater 6 are made of carbon. In particular, the core tube 5 and the heater 6 are preferably high-purity carbon in order to prevent impurities from adhering to the glass base material G.
The heater 6 can be heated by resistance by being energized, and the core tube 5 is heated by the heater 6 to be heated. However, the heater 6 may generate heat by an induction heating method.
Furthermore, the heating furnace 2 is configured so that an inert gas such as nitrogen can be introduced into a space inside the heating furnace 2 in which the glass base material G is disposed.

また、炉心管５の内径は、例えば直径１００ｍｍである。この場合、延伸を行うガラス母材Ｇは、例えば直径が８０ｍｍ程度のものを使用することができる。   The inner diameter of the core tube 5 is, for example, 100 mm in diameter. In this case, as the glass base material G to be stretched, for example, one having a diameter of about 80 mm can be used.

また、炉心管５の上方には、ガラス母材Ｇを炉心管５の内側に導入するための空間を形成する上筒７が設けられている。そして、この上筒７の上端には開閉可能な上蓋８が取り付けられている。   Further, an upper cylinder 7 that forms a space for introducing the glass base material G into the core tube 5 is provided above the core tube 5. An upper lid 8 that can be opened and closed is attached to the upper end of the upper cylinder 7.

ガラス母材Ｇの両端には、それぞれダミー棒Ｇ１，Ｇ２が接続されており、一方のダミー棒Ｇ１が上部チャック３に把持され、他方のダミー棒Ｇ２が下部チャック４に把持される。ダミー棒Ｇ１，Ｇ２は、ガラス製のものを好適に用いることができる。
ダミー棒Ｇ１，Ｇ２を含むガラス母材Ｇは、上部チャック３と下部チャック４とによって支持される。本実施形態では、上部チャック３に荷重測定器（ロードセル）１０が取り付けられており、ダミー棒Ｇ１と上部チャック３との間にかかる荷重、すなわち上部チャック３がガラス母材Ｇを支持している荷重を測定することができる。 Dummy rods G 1 and G 2 are connected to both ends of the glass base material G, one dummy rod G 1 is held by the upper chuck 3, and the other dummy rod G 2 is held by the lower chuck 4. As the dummy rods G1 and G2, those made of glass can be suitably used.
The glass base material G including the dummy rods G 1 and G 2 is supported by the upper chuck 3 and the lower chuck 4. In this embodiment, a load measuring device (load cell) 10 is attached to the upper chuck 3, and the load applied between the dummy rod G 1 and the upper chuck 3, that is, the upper chuck 3 supports the glass base material G. The load can be measured.

また、上部チャック３及び下部チャック４はそれぞれ昇降装置（図示せず）に取り付けられており、制御部９によってその駆動が制御される。上部チャック３は、加熱炉２内へのガラス母材Ｇの送り装置として機能する。下部チャック４は、延伸したガラス母材Ｇの引取り装置として機能する。これらの上部チャック３及び下部チャック４の昇降をそれぞれ制御することによって、ガラス母材Ｇの位置制御を行ってガラス母材Ｇに対して適切な加熱を行うことができるとともに、ガラス母材Ｇに張力を加えて、加熱されて軟化した領域を延伸して細径化することができる。
その際、荷重測定器１０の測定値は、制御部９により検出される。 The upper chuck 3 and the lower chuck 4 are each attached to an elevating device (not shown), and the driving of the upper chuck 3 and the lower chuck 4 is controlled by the control unit 9. The upper chuck 3 functions as a feeding device for the glass base material G into the heating furnace 2. The lower chuck 4 functions as a drawing device for the stretched glass base material G. By controlling the raising and lowering of the upper chuck 3 and the lower chuck 4, the glass base material G can be appropriately heated by controlling the position of the glass base material G. By applying tension, the heated and softened region can be stretched to reduce the diameter.
At that time, the measurement value of the load measuring device 10 is detected by the control unit 9.

また、制御部９はヒータ６に流す電流量を制御して、ヒータ６の発熱温度を制御することができる。ヒータ６に流す電流量は、炉心管５の内側表面の最高温度が所定の値となるように制御すると良い。炉心管５の温度は、加熱炉２に取り付けられた放射温度計によって測定することができる。   Further, the control unit 9 can control the heat generation temperature of the heater 6 by controlling the amount of current flowing through the heater 6. The amount of current flowing through the heater 6 is preferably controlled so that the maximum temperature of the inner surface of the core tube 5 becomes a predetermined value. The temperature of the core tube 5 can be measured by a radiation thermometer attached to the heating furnace 2.

この延伸装置１を用いてガラス母材Ｇの延伸を行うには、まず、荷重測定器１０が取り付けられた上部チャック３によりダミー棒Ｇ１を把持し、上蓋８を開いて上筒７の上方から加熱炉２内にガラス母材Ｇを導入する。そして、ガラス母材Ｇの下部のダミー棒Ｇ２を下部チャック４により把持し、上部チャック３と下部チャック４の位置を制御して、ガラス母材Ｇの下端近傍部分が最初に加熱されるように炉心管５の内側にガラス母材Ｇを配置する。なお、このとき上部チャック３と下部チャック４との間でガラス母材Ｇに若干の張力を作用させ、ガラス母材Ｇの位置を安定させる。   In order to stretch the glass base material G using the stretching device 1, first, the dummy rod G 1 is gripped by the upper chuck 3 to which the load measuring device 10 is attached, the upper lid 8 is opened, and the upper cylinder 7 is viewed from above. A glass base material G is introduced into the heating furnace 2. Then, the lower dummy rod G2 of the glass base material G is held by the lower chuck 4, and the positions of the upper chuck 3 and the lower chuck 4 are controlled so that the vicinity of the lower end of the glass base material G is heated first. A glass base material G is disposed inside the furnace core tube 5. At this time, a slight tension is applied to the glass base material G between the upper chuck 3 and the lower chuck 4 to stabilize the position of the glass base material G.

ガラス母材Ｇが炉心管５の内側に配置されるときには、ガラス母材Ｇの急激な加熱を避けるため、ヒータ６に電流を流さずにヒータ６及び炉心管５を室温のままとしておく。もしくは、炉心管５を延伸温度より低い温度に加熱しておく。好ましくは、炉心管５の内側表面の最高温度が１１００℃以下となるようにしておくと良い。   When the glass base material G is disposed inside the furnace core tube 5, the heater 6 and the core tube 5 are left at room temperature without passing an electric current through the heater 6 in order to avoid rapid heating of the glass base material G. Alternatively, the core tube 5 is heated to a temperature lower than the stretching temperature. Preferably, the maximum temperature of the inner surface of the core tube 5 should be 1100 ° C. or lower.

ガラス母材Ｇを延伸させる際の炉心管５の温度は、上記のように１７００℃から１９００℃程度の高温であるため、この延伸温度の状態でガラス母材Ｇを炉心管５の内側に配置した場合には、急激な加熱が行われることとなって、ガラス母材Ｇに歪みやクラックが発生してしまうおそれがある。例えば、ガラス母材Ｇとダミー棒Ｇ２との境界部分にクラックが発生しやすい。そのため、本実施形態では、ガラス母材Ｇを延伸開始位置に配置した後、炉心管５の温度を延伸温度まで昇温させるようにしている。そして、ガラス母材Ｇが延伸を良好に行うことのできる温度まで加熱されて十分に軟化したことを検知した後に、下部チャック４を下方に移動させてガラス母材Ｇの延伸を開始する。   Since the temperature of the core tube 5 when the glass base material G is stretched is as high as about 1700 ° C. to 1900 ° C. as described above, the glass base material G is disposed inside the core tube 5 at this stretching temperature. In such a case, the glass base material G may be distorted or cracked due to rapid heating. For example, cracks are likely to occur at the boundary between the glass base material G and the dummy bar G2. For this reason, in the present embodiment, after the glass base material G is disposed at the stretching start position, the temperature of the core tube 5 is raised to the stretching temperature. Then, after detecting that the glass base material G is heated to a temperature at which it can be satisfactorily stretched and is sufficiently softened, the lower chuck 4 is moved downward to start stretching the glass base material G.

図２に、本実施形態における、ガラス母材Ｇの延伸を開始する際の上部チャック３の荷重Ｆ（Ｎ）の時間軸変化と炉心管５の内側表面の最高温度Ｔ（℃）の時間軸変化のグラフを示す。
まず、時間軸（横軸）の開始点（グラフ中左端）は、ガラス母材Ｇが延伸開始位置に配置された時を示しており、この時の炉心管５の温度Ｔは室温である。そして、これ以降にヒータ６への通電を開始して炉心管５の温度Ｔを昇温させる。炉心管５の温度Ｔが延伸温度近くまで上がると、ガラス母材Ｇの下端近傍部分は加熱されて徐々に軟化していく。そして、炉心管５の温度Ｔが延伸温度で安定した直後にはガラス母材Ｇの軟化は外周近傍部分のみであり、その後ある程度の時間が経過してから、ガラス母材Ｇは内部まで十分に軟化される。 FIG. 2 shows the time axis change of the load F (N) of the upper chuck 3 when starting the drawing of the glass base material G and the time axis of the maximum temperature T (° C.) of the inner surface of the core tube 5 in this embodiment. The graph of change is shown.
First, the starting point (left end in the graph) of the time axis (horizontal axis) indicates the time when the glass base material G is disposed at the drawing start position, and the temperature T of the core tube 5 at this time is room temperature. Thereafter, energization of the heater 6 is started and the temperature T of the core tube 5 is raised. When the temperature T of the core tube 5 rises to near the stretching temperature, the vicinity of the lower end of the glass base material G is heated and gradually softens. Immediately after the temperature T of the furnace core tube 5 is stabilized at the stretching temperature, the glass base material G is softened only in the vicinity of the outer periphery, and after a certain amount of time has passed, the glass base material G is sufficiently expanded to the inside. Softened.

ガラス母材Ｇが軟化する前は、ガラス母材Ｇとダミー棒Ｇ１，Ｇ２の総重量が上部チャック３と下部チャック４とに分配されて支持されているが、ガラス母材Ｇの下端近傍部分が軟化するにつれて、ガラス母材Ｇの下端近傍部分とダミー棒Ｇ２の重量は下部チャック４により支持され、ガラス母材Ｇの大部分とダミー棒Ｇ１の重量は上部チャック３により支持されるようになる。したがって、図２に示すように、上部チャック３にかかる荷重はガラス母材Ｇの下端近傍部分の軟化とともに増加し、内部まで十分に軟化された後は荷重が所定の値で安定する。そして、制御部９では、炉心管５の温度を延伸温度に昇温させた後に、荷重測定器１０から検出した荷重の測定値が予め設定された所定時間ｔ１（秒）にわたって安定したことを検知すると、ガラス母材Ｇが十分に軟化したとみなして、上部チャック３及び下部チャック４の移動を開始して延伸を行う。   Before the glass base material G is softened, the total weight of the glass base material G and the dummy rods G1 and G2 is distributed and supported by the upper chuck 3 and the lower chuck 4, but a portion near the lower end of the glass base material G. So that the weight of the glass base material G near the lower end and the weight of the dummy bar G2 is supported by the lower chuck 4, and the weight of the glass base material G and the weight of the dummy bar G1 are supported by the upper chuck 3. Become. Therefore, as shown in FIG. 2, the load applied to the upper chuck 3 increases with the softening of the vicinity of the lower end of the glass base material G, and the load is stabilized at a predetermined value after being sufficiently softened to the inside. Then, the control unit 9 detects that the measured value of the load detected from the load measuring instrument 10 is stable for a predetermined time t1 (seconds) after the temperature of the core tube 5 is raised to the stretching temperature. Then, it is considered that the glass base material G is sufficiently softened, and the upper chuck 3 and the lower chuck 4 are moved to perform stretching.

なお、荷重Ｆや温度Ｔの一例を示すと、ガラス母材Ｇの外径が８０ｍｍで、ダミー棒Ｇ１，Ｇ２を含めたガラス母材Ｇの総重量が例えば１１ｋｇｆである場合は、炉心管５の温度Ｔを１８００℃まで昇温させて、ガラス母材Ｇの下端近傍部分が軟化した後に荷重が安定して荷重測定器１０で検出される値は８ｋｇｆである。また、本実施形態では、軟化を判断する上記の所定時間ｔ１を６０秒とした。   As an example of the load F and temperature T, when the outer diameter of the glass base material G is 80 mm and the total weight of the glass base material G including the dummy rods G1 and G2 is, for example, 11 kgf, the core tube 5 After the temperature T is raised to 1800 ° C. and the vicinity of the lower end of the glass base material G is softened, the load is stably detected and the value detected by the load measuring instrument 10 is 8 kgf. In the present embodiment, the predetermined time t1 for determining softening is 60 seconds.

以上説明した本実施形態のガラス母材の延伸方法によれば、ガラス母材を支持する荷重の変化によりガラス母材が十分に軟化したことを検知して、その後延伸を開始するため、ガラス母材を把持する部分にかかる負荷を低減することができる。したがって、ガラス母材の歪みや割れを防止するとともに、延伸装置の運転を停止させることも防ぐことができる。   According to the glass base material stretching method of the present embodiment described above, the glass base material is detected by detecting that the glass base material is sufficiently softened due to a change in the load supporting the glass base material, and then starts stretching. It is possible to reduce the load applied to the portion that holds the material. Therefore, it is possible to prevent the glass base material from being distorted and broken and to stop the operation of the stretching apparatus.

なお、上記の実施形態では、力測定器を上部チャックに取り付けてガラス母材を支持する荷重を測定したが、下部チャックに荷重測定器を取り付けて、ガラス母材を下方で支持する荷重を測定することによってガラス母材の軟化を検出しても良い。その場合には、ガラス母材の軟化に伴って、測定される荷重は減少していき、十分に軟化されたときにその測定値は安定する。
また、荷重測定器を取り付ける位置は、上部または下部のチャックに限らず、チャックを昇降させる昇降装置に取り付けても良い。 In the above embodiment, the load for supporting the glass base material is measured by attaching the force measuring instrument to the upper chuck, but the load for supporting the glass base material is measured by attaching the load measuring instrument to the lower chuck. By doing so, the softening of the glass base material may be detected. In that case, the measured load decreases as the glass base material softens, and the measured value stabilizes when the glass base material is sufficiently softened.
Further, the position where the load measuring device is attached is not limited to the upper or lower chuck, but may be attached to an elevating device that elevates the chuck.

さらに、本発明はガラス母材を横（水平）方向に配置して、横方向に延伸させる場合にも適用可能である。横方向に延伸する場合には、ガラス母材の自重による変形の影響を抑えるためにガラス母材を軸回りに回転させながら張力をかけていく。その際、チャックにロードセルまたはトルクセンサ等の荷重測定器を取り付けて、延伸開始前にチャックにかかる荷重を測定することで、上記の縦型の延伸方法と同様に荷重の上昇または下降の変化の後に測定値が安定したことを検出して、ガラス母材が十分に軟化したことを検知することができる。   Furthermore, the present invention can also be applied to a case where the glass base material is disposed in the lateral (horizontal) direction and is stretched in the lateral direction. In the case of stretching in the lateral direction, tension is applied while rotating the glass base material around the axis in order to suppress the influence of deformation due to the weight of the glass base material. At that time, a load measuring device such as a load cell or a torque sensor is attached to the chuck, and the load applied to the chuck is measured before starting the stretching, so that the change in the increase or decrease of the load is similar to the above vertical stretching method. It is possible to detect that the glass base material has been sufficiently softened by detecting that the measured value has been stabilized later.

本発明に係る延伸装置を示す既略断面図である。It is an approximate sectional view showing the extending device concerning the present invention. ガラス母材の延伸を開始する際のチャックの荷重と炉心管の温度の変化を示すグラフである。It is a graph which shows the load of the chuck | zipper at the time of starting extending | stretching of a glass base material, and the change of the temperature of a core tube.

符号の説明Explanation of symbols

１ 延伸装置
２ 加熱炉
３ 上部チャック
４ 下部チャック
５ 炉心管
６ ヒータ
７ 上筒
８ 上蓋
９ 制御部
１０ 荷重測定器
Ｇ ガラス母材
Ｇ１，Ｇ２ ダミー棒 DESCRIPTION OF SYMBOLS 1 Stretching apparatus 2 Heating furnace 3 Upper chuck 4 Lower chuck 5 Furnace core tube 6 Heater 7 Upper cylinder 8 Upper lid 9 Control part 10 Load measuring instrument G Glass base material G1, G2 Dummy rod

Claims (4)

加熱部を備えた加熱炉内にガラス母材を配置し、前記加熱部により前記ガラス母材を加熱して、前記ガラス母材を支持している荷重を測定し、加熱開始後に前記測定した荷重が所定の時間にわたり所定の値になった後、前記ガラス母材の延伸を開始するガラス母材の延伸方法。   A glass base material is arranged in a heating furnace provided with a heating unit, the glass base material is heated by the heating unit, a load supporting the glass base material is measured, and the measured load after heating is started. After the glass has reached a predetermined value over a predetermined time, the glass base material is stretched. 前記荷重は、前記ガラス母材をその両端を把持して垂直方向に配置し、その上端側で前記ガラス母材を支持している荷重である請求項１に記載のガラス母材の延伸方法。   2. The glass base material stretching method according to claim 1, wherein the load is a load in which the glass base material is gripped at both ends thereof and arranged in a vertical direction, and the glass base material is supported on an upper end side thereof. 前記加熱炉内に前記ガラス母材を配置した後、前記加熱部の温度を１７００℃以上に昇温させてから延伸を開始する請求項１または２に記載のガラス母材の延伸方法。   The glass base material stretching method according to claim 1, wherein after the glass base material is arranged in the heating furnace, the temperature of the heating unit is increased to 1700 ° C. or higher and then stretching is started. 前記加熱炉内に前記ガラス母材を配置する際の前記加熱部の温度を１１００℃以下とする請求項１から３の何れか１項に記載のガラス母材の延伸方法。   The glass base material stretching method according to any one of claims 1 to 3, wherein a temperature of the heating unit when the glass base material is disposed in the heating furnace is set to 1100 ° C or lower.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013230960A (en) * 2012-05-02 2013-11-14 Shin-Etsu Chemical Co Ltd Method and apparatus for elongating glass base material
JP2015083535A (en) * 2014-10-30 2015-04-30 信越化学工業株式会社 Drawing device of glass preform
US11454580B2 (en) 2014-10-14 2022-09-27 Heraeus Quartz North America Llc Method for preform or tube drawing based on its viscosity

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013230960A (en) * 2012-05-02 2013-11-14 Shin-Etsu Chemical Co Ltd Method and apparatus for elongating glass base material
US9371246B2 (en) 2012-05-02 2016-06-21 Shin-Etsu Chemical Co., Ltd. Glass base material elongating method and glass base material elongating apparatus
US9862635B2 (en) 2012-05-02 2018-01-09 Shin-Etsu Chemical Co., Ltd. Glass base material elongating method and glass base material elongating apparatus
US11454580B2 (en) 2014-10-14 2022-09-27 Heraeus Quartz North America Llc Method for preform or tube drawing based on its viscosity
JP2015083535A (en) * 2014-10-30 2015-04-30 信越化学工業株式会社 Drawing device of glass preform

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