JP4062410B2 - Manufacturing method and manufacturing apparatus for glass pipe for optical fiber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for manufacturing an optical fiber glass pipe, and more particularly to an optical fiber glass pipe manufacturing method and an apparatus for manufacturing an optical fiber glass pipe by a piercing method.
[0002]
[Prior art]
In the production of optical fiber glass pipes so far, a cold working method using a drill, a method of applying ultrasonic waves to the tip of the drill, and a glass rod as a material being heated and softened, for example, at a high temperature. There is a piercing method in which a carbon jig that can withstand is inserted.
[0003]
An example of this piercing method is disclosed in Japanese Patent No. 2798465. FIG. 5 shows a manufacturing apparatus 30 for manufacturing a glass cylinder such as an optical fiber glass pipe by the piercing method.
In other words, an inlet side bed 32 is provided on the left side and an outlet side bed 33 is provided on the right side in FIG. 5 with a heating furnace 31 as a heating means, for example, being a high frequency induction furnace.
[0004]
On the entrance bed 32, a first spindle feed table 34 is provided as a moving means that is movable in the carry-in direction (left-right direction). Chucks 35 and 36 are provided on both sides of the first spindle feed table 34, and a long glass rod 37 as a workpiece is held by the chuck 36 on the heating furnace 31 side (right side in FIG. 5). And rotated by a rotation drive mechanism.
[0005]
The tip of the glass rod 37 supported by the first spindle feed table 34 is positioned inside the heating furnace 31, and when a predetermined alternating current is energized to the coil 38, a heating element 39 such as graphite generates heat. The glass rod 37 is heated to the softening point.
In order to stabilize the posture of the long glass rod 37, a support roller 40 is provided at an intermediate position. The position of the support roller 40 can be adjusted in the vertical direction and in the horizontal direction in FIG.
[0006]
On the other hand, on the outlet side bed 33, a second spindle feed table 41 is provided as moving means that can move in the left-right direction in FIG. Chuckes 42 and 43 are provided on both sides of the second spindle feed table 41, and a quartz glass dummy cylinder 44 is rotatably held by the chuck 42 on the heating furnace 31 side.
The tip of the dummy cylinder 44 is fitted to the outer periphery of a drawing die 45 provided integrally with the heating element 39 of the heating furnace 31, and the tip of the dummy cylinder 44 is a long workpiece that is a workpiece. The glass rod 37 is fused to the front end surface.
[0007]
Further, a fixed base 46 is fixedly provided at the right end of the outlet side bed 33 in FIG. 5, and one end (right end) of the fixed shaft 47 is supported. The other end (left end) of the fixed shaft 47 reaches the center of the heating furnace 31 through the inside of the dummy cylinder 44, and the tip is smaller than the outer diameter of the glass rod 37 and is made of carbon. A drilling jig 48 that can withstand high temperatures is attached.
[0008]
Therefore, when drilling the glass rod 37, first, the first spindle feed table 34 and the second spindle feed table 41 are restrained from moving in the loading direction, and the end of the glass rod 37 and the end of the dummy cylinder 44 The glass rod 37 is heated and fused to the softening point in the heating furnace 31 while rotating concentrically and rotating.
At this time, the fixed shaft 47 to which the drilling jig 48 is attached is fitted in the dummy cylinder 44 in advance, and the tip of the drilling jig 48 is engaged with the center of the tip of the glass rod 37.
[0009]
Next, the first spindle feed table 34 and the second spindle feed table 41 are confirmed while rotating the glass rod 37 and the dummy cylinder 44 after confirming that the glass rod 37 is in a heated state capable of being drawn. Is moved in the loading direction at a predetermined feed rate.
As described above, the glass pipe for optical fiber is formed from the glass rod 37 by the piercing method.
[0010]
According to such a piercing method, it is excellent in that the inner surface of the hole processed by the drilling jig 48 is smooth, and that large and long base materials can be opened with a high yield. Yes.
[0011]
[Problems to be solved by the invention]
By the way, in the processing by the piercing method, it is ideal that the viscosity of the glass rod 37 at the penetration portion is always constant, and there is no variation in the dimensions such as the residual stress after processing and the outer diameter and inner diameter of the product.
However, in the conventional piercing method as described above, since the processing viscosity is different in the part where the shape of the glass rod changes slightly during processing, the distribution of residual stress after cooling causes cracks during reheating. There is a problem in that, for example, it tends to occur, and the dimensional accuracy after processing deteriorates, so that the characteristics in the longitudinal direction after fiber formation change.
[0012]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a method of manufacturing a glass pipe for an optical fiber that can prevent variations in residual stress and dimensions by perforating under the same viscosity. And providing a manufacturing apparatus.
[0013]
[Means for Solving the Problems]
In order to achieve the above-described object, a method for manufacturing a glass pipe for optical fiber according to the present invention, as described in claim 1, heats a glass material mainly composed of quartz glass and having a circular outer shape by a heating means. The optical fiber glass pipe is made by softening and piercing a drilling jig having an outer diameter smaller than the outer diameter of the glass material relative to the end of the glass material in the axial direction. And
A penetration pressure when the drilling jig is penetrated into the glass material at a constant speed is detected, and the heating means is controlled so that the penetration pressure becomes constant by feeding back the detection signal. .
[0014]
Here, as a glass raw material used as a material, a solid glass rod or a hollow glass pipe having a small hole in the center can be used. As a heating means, a high-frequency induction furnace, an electric resistance furnace, or the like can be used, but a high-frequency induction furnace having a high temperature rise / fall rate is preferable. Moreover, the penetration pressure at the time of penetrating the drilling jig into the glass material can be detected by using a load sensor such as a load cell. Alternatively, it is possible to detect from the power consumption for driving the moving means.
When the drilling jig is relatively inserted into the glass material, the drilling jig is fixed in the heating means, and the glass material is pushed into the drilling jig while being rotated. preferable.
[0015]
In the manufacturing method of the optical fiber glass pipe configured as described above, the softening state of the glass material can be determined from the pressure when the drilling jig is inserted into the glass material at a constant speed. When is small, the heating by the heating means can be reduced to lower the temperature and softening can be reduced. Alternatively, when the penetration pressure is high, the heating by the heating means can be strengthened to raise the temperature and further soften.
Therefore, in this method of manufacturing a glass pipe for optical fibers, the glass material to be perforated can be in an appropriate softened state, so that it can be perforated under the same viscosity.
As a result, since the processing viscosity is different from the conventional one, the distribution of residual stress after cooling causes cracks during reheating, and the dimensional accuracy after processing deteriorates. The problem of deteriorating the longitudinal fluctuation of the material can be solved.
[0016]
The apparatus for manufacturing a glass pipe for an optical fiber according to the present invention is characterized in that, as described in claim 2, a glass material whose main component is quartz glass and whose outer shape is circular is heated and softened by a heating means, An apparatus for manufacturing a glass pipe for an optical fiber, in which a drilling jig having an outer diameter smaller than the diameter of the glass material is axially penetrated from the end of the glass material in the heating means by the moving means to open the hole. There,
The penetration pressure becomes constant based on a detection signal from the penetration pressure detection means for detecting the penetration pressure when the jig for drilling is penetrated into the glass material at a constant speed. And a control device for controlling the heating means.
[0017]
Here, as a glass raw material used as a material, a solid glass rod or a hollow glass pipe having a small hole in the center can be used. As a heating means, a high-frequency induction furnace, an electric resistance furnace, or the like can be used, but a high-frequency induction furnace having a high temperature rise / fall rate is preferable. In addition, the penetration pressure when the drilling jig is inserted into the glass material can be detected by the power detection means such as the load sensor such as a load cell and the power consumption (current, voltage, etc.) of the moving means such as a motor. The detection signal is fed back to the control device.
When the drilling jig is relatively inserted into the glass material, the drilling jig is fixed in the heating means, and the glass material is pushed into the drilling jig while being rotated. preferable.
[0018]
In the optical fiber glass pipe manufacturing apparatus configured as described above, the pressure when the drilling jig is inserted into the glass material at a constant speed is detected by the intrusion pressure detecting means, and this detection signal is fed back to the control apparatus. By doing so, it is possible to determine the softening state of the glass material. Therefore, when the penetration pressure is small, the heating by the heating means can be reduced by the control device to reduce the temperature and the softening can be reduced. Alternatively, when the penetration pressure is high, the control device can promote heating by the heating means to raise the temperature and promote softening.
Therefore, in this optical fiber glass pipe manufacturing apparatus, the glass material to be perforated can be in an appropriate softened state, so that it can be perforated under the same viscosity.
As a result, since the processing viscosity is different from the conventional one, the distribution of residual stress after cooling causes cracks during reheating, and the dimensional accuracy after processing deteriorates. The problem of deteriorating the longitudinal fluctuation of the material can be solved.
[0019]
Moreover, the manufacturing apparatus of the glass pipe for optical fibers which concerns on this invention is the manufacturing apparatus of the glass pipe for optical fibers described in Claim 2 as described in Claim 3, The said penetration pressure detection means is the said piercing | piercing. The load cell is provided at the rear end of the fixed shaft with the jig attached to the front end.
[0020]
In the optical fiber glass pipe manufacturing apparatus configured as described above, the pressure when the drilling jig is inserted into the glass material is detected by the load cell via the fixed shaft to which the drilling jig is attached. be able to.
[0021]
Moreover, the manufacturing apparatus of the glass pipe for optical fibers which concerns on this invention is the manufacturing apparatus of the glass pipe for optical fibers described in Claim 2 as described in Claim 4, The said penetration pressure detection means is the said movement. The power detection means detects power consumed by the means.
[0022]
In the optical fiber glass pipe manufacturing apparatus configured as described above, the power consumption of the moving means for moving the jig relative to the glass material when the punching jig penetrates the glass material. Can be detected by detecting the power using the power detection means.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments according to the present invention will be described below in detail with reference to the drawings. In the embodiment described below, the members and the like already described in FIG. 5 are denoted by the same or corresponding reference numerals in the drawing, and the description is simplified or omitted.
[0024]
1 to 4 show an embodiment of an optical fiber glass pipe manufacturing apparatus according to the present invention. In this optical fiber glass pipe manufacturing apparatus 10, a high-frequency induction furnace is used as a heating furnace 31 that is a heating means for softening and processing a glass material, and this heating furnace 31 is connected to the control device 11. Has been. Further, as another heating means of the high frequency induction furnace, one that can raise the temperature up to about 2000 ° C. that makes it possible to soften and process the quartz glass using an electric resistance furnace using a carbon heater can be used. The high-frequency induction furnace is preferable because it can control the temperature rise and fall quickly, and enables high-precision control.
[0025]
Further, as shown in FIG. 2, a load cell 12 as an intrusion pressure detecting means is attached between the rear end portion of the fixed shaft 47 to which the drilling jig 48 is attached at the front end and the fixed base 46. The load cell 12 is connected to the control device 11.
The first spindle feed table 34 as a moving means that holds the glass rod 37 as a glass material is moved by a moving means (not shown) and is moved and supplied to the heating furnace 31 at a constant speed.
[0026]
Next, the manufacturing method of the glass pipe for optical fibers using the manufacturing apparatus 10 of the glass pipe for optical fibers mentioned above is demonstrated.
When the tip of the glass rod 37 is softened by the heating furnace 31, the first spindle feed table 34 is moved to the heating furnace 31 side, and the glass rod 37 is fed at a constant speed. At this time, the tip of the glass rod 37 is pushed outward (outer peripheral side) by the drilling jig 48 to provide the internal space 14.
As the glass rod 37 is carried in, an inert gas 13 such as N ₂ or Ar is supplied in the carrying-in direction.
[0027]
The penetration pressure when the glass rod 37 is carried and pressed against the drilling jig 48 is detected by the load cell 12 via the fixed shaft 47 and fed back to the control device 11.
In the control device 11, if the fed-in penetration pressure is smaller than a predetermined pressure, it is determined that the glass rod 37 is too soft and the temperature of the heating furnace 31 is lowered. On the other hand, when the penetration pressure is higher than the predetermined pressure, it is determined that the glass rod 37 is not sufficiently softened, and the heating furnace 31 is heated.
[0028]
FIG. 3 shows another embodiment of the optical fiber glass pipe manufacturing apparatus according to the present invention. In this manufacturing apparatus, the first spindle feed table 34 is driven by the motor 50 toward the heating furnace 31, and numerical values such as current and voltage supplied to the motor 50 are detected by the control device 51. When the detected current value or voltage value is smaller than a predetermined value, the control device 51 determines that the glass rod 37 is too soft and lowers the temperature of the heating furnace 31.
[0029]
On the other hand, if the detected current value or voltage value is larger than a predetermined value, it is determined that the glass rod 37 is not sufficiently softened, and the heating furnace 31 is heated. Thus, by detecting the current value and voltage value of the drive motor 50 of the first spindle feed table 34, the softened state of the glass rod 37 can be detected, and from the detected current value and voltage value. The control device 51 performs feedback control of raising and lowering the temperature of the heating furnace 31, so that the softening of the glass rod 37 disposed in the heating furnace 31 can always be kept constant.
[0030]
FIG. 4 shows an apparatus for manufacturing an optical fiber glass pipe according to the present invention, which includes a flow rate control device. A furnace core tube 55 is disposed inside the heating furnace 31 of the manufacturing apparatus, and a glass pipe is manufactured in the furnace core tube 55. An inert gas 13 is introduced into the furnace core tube 55 via a flow control device 56. The softened state of the glass rod 37 disposed in the furnace core tube 55 depends on the current value and voltage value of the drive motor 50 of the load cell 12 connected to the fixed shaft 47 and the first spindle feed table 34 described above. To be judged. In order to maintain the softened state of the glass rod 37 at a desired constant level, if a slight temperature increase or decrease in temperature is required in the vicinity of the furnace 31 of the furnace core tube 55, the glass rod 37 is introduced into the furnace core tube 55. The temperature can be controlled by controlling the flow rate of the inert gas.
[0031]
That is, when the glass rod 37 is slightly softened more than desired, the flow rate control device 56 is controlled to increase the flow rate of the inert gas, thereby slightly reducing the ambient temperature in the furnace core tube 55. It is possible to lower it. In addition, when a slight temperature increase is necessary, the ambient temperature can be slightly increased by reducing the flow rate of the inert gas by the flow rate control device 56.
[0032]
According to the optical fiber glass pipe manufacturing method and manufacturing apparatus 10 as described above, the glass rod 37 can always be pierced with a constant viscosity, so that residual stress and dimensional variations can be prevented, and cooling can be performed. It is possible to avoid problems such as the distribution of the residual stress later and the occurrence of cracks during reheating, and the fluctuation of the longitudinal characteristics after fiberization due to the deterioration of dimensional accuracy after processing. .
Further, when the glass rod 37 is carried into the heating furnace 31, the amount of the inert gas 13 supplied between the heating furnace 31 and the glass rod 37 is also controlled at the same time, so that the responsiveness and high accuracy of the control can be achieved. Can be planned.
[0033]
In addition, the manufacturing method and manufacturing apparatus of the glass pipe for optical fibers of this invention are not limited to embodiment mentioned above, A suitable deformation | transformation, improvement, etc. are possible.
That is, in the above-described embodiment, the load cell 12 is provided on the fixed shaft 47 as an intrusion pressure detecting means, but in addition, when a motor, a ball nut, a ball screw, and the like are provided to move the first spindle feed table 34. May be provided with power detection means for detecting the power consumed by the motor, and the penetration pressure may be determined from this power consumption.
[0034]
【The invention's effect】
As described above, according to the method and apparatus for manufacturing a glass pipe for optical fiber according to the present invention, the glass material to be punched can be in an appropriate softened state, so that it can be punched under the same viscosity. To solve problems such as residual stress distribution after cooling and cracking during reheating, and deterioration of longitudinal characteristics of the fiber after fiber processing due to deterioration of dimensional accuracy after processing. Can do.
[Brief description of the drawings]
FIG. 1 is an overall view showing an embodiment of an optical fiber glass pipe manufacturing apparatus according to the present invention.
FIG. 2 is a cross-sectional view showing the main part of the optical fiber glass pipe manufacturing apparatus according to the present invention.
FIG. 3 is an overall view showing another embodiment of the optical fiber glass pipe manufacturing apparatus according to the present invention.
FIG. 4 is a schematic view of an essential part of the apparatus for manufacturing a glass pipe for optical fiber according to the present invention, which is provided with a flow rate control device.
FIG. 5 is an overall view showing an apparatus for manufacturing an optical fiber glass pipe by a conventional piercing method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Manufacturing apparatus 11 Control apparatus 12 Load cell (penetration pressure detection means)
31 Heating furnace (heating means)
34 First spindle feed table (moving means)
37 Glass rod (glass material)
47 Fixed shaft 48 Drilling jig

Claims (4)

A glass material whose main component is quartz glass and whose outer shape is circular is heated and softened by a heating means, and a drilling jig having an outer diameter smaller than the outer diameter is relative to the end of the glass material in the axial direction. A method of manufacturing a glass pipe for optical fiber that is penetrated and opened,
A penetration pressure when the drilling jig is penetrated into the glass material at a constant speed is detected, and the heating means is controlled so that the penetration pressure becomes constant by feeding back the detection signal. Manufacturing method of glass pipe for optical fiber. A glass material mainly composed of quartz glass and having a circular outer shape is heated and softened by a heating means, and a drilling jig having an outer diameter smaller than the diameter of the outer shape is moved in the heating means by the moving means. An apparatus for manufacturing a glass pipe for an optical fiber that is opened by being penetrated relatively in the axial direction from the end of
The penetration pressure becomes constant based on a detection signal from the penetration pressure detection means for detecting the penetration pressure when the jig for drilling is penetrated into the glass material at a constant speed. An apparatus for manufacturing a glass pipe for optical fibers, comprising a control device for controlling the heating means. The apparatus for producing a glass pipe for an optical fiber according to claim 2, wherein the penetration pressure detecting means is a load cell provided at a rear end of a fixed shaft having the drilling jig attached to a tip. The apparatus for manufacturing a glass pipe for an optical fiber according to claim 2, wherein the penetration pressure detection means is a power detection means for detecting power consumed by the moving means.

Images