JPH0710582A - Cutting method and device for optical fiber preform - Google Patents

Abstract

PURPOSE:To eliminate the occurrence of cracking and residual stress in an optical fiber preform. CONSTITUTION:This cutting method for the optical fiber preform has a stage for holding and fixing the optical fiber preform 1 to a rotary cutter 5 in such a manner that the respective axial lines are paralleled, a stage for rotationally driving both of the optical fiber preform 1 and the rotary cutter 5 in the same direction or opposite directions at a proper rotating speed and a stage for feeding the optical fiber preform 1 at a proper cutting in speed while rotting the rotary cutter 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cutting both ends of an optical fiber preform so as to leave an effective portion in the center thereof, and a cutting device used in that case.

[0002]

2. Description of the Related Art As shown in FIG. 4, an optical fiber preform 1 made by depositing soot by the VAD method, for example, has a center portion in the longitudinal direction in which the diameter ratio of the core 1A and the cladding 1B is accurately set to a predetermined value. Although it is formed, it does not always have this predetermined diameter ratio at both ends,
Before the stretching step, a cutting step is performed in which both end portions are cut to leave this central portion called a so-called effective portion.

[0003]

This cutting process is conventionally carried out by applying a rotary cutter of a diamond blade to a fixed optical fiber preform. When the cutting is started by the rotary cutter, the optical fiber preform is rotated. The compressive stress due to the pressing force acting from the cutter and the bending stress of the optical fiber preform, which is one beam member, tend to be concentrated at the contact point with the first cutter, which causes cracks in the optical fiber preform in extreme cases. Alternatively, there is a drawback that it breaks and becomes unusable, and even if it is not so severe, this stress concentration has an adverse effect on the transmission characteristics of the optical fiber of the product later.

[0004]

The present invention has been made to solve this problem, and the means of the invention according to claim 1 to solve the problem is to use an optical fiber preform as a rotary cutter. On the other hand, a step of holding and fixing such that the respective axes are parallel to each other, a step of rotationally driving the optical fiber preform and the rotary cutter in the same direction or in opposite directions at an appropriate rotation speed, and the rotary cutter. And a step of feeding the optical fiber preform with an appropriate cutting speed while rotating the optical fiber preform.

The means of the invention according to claim 2 is a device for holding and fixing an optical fiber preform to be cut, a rotation supporting device for rotatably supporting the tip of the optical fiber preform, and the optical fiber. A cutting unit including a rotary shaft parallel to the axis of the base material and a rotary cutter attached to an end of the rotary shaft and having a rotation surface orthogonal to the axis, and the cutting unit orthogonal to the axis of the optical fiber base material. It is a cutting device of an optical fiber preform having a cutting feed device for feeding in a direction.

[0006]

Since the optical fiber preform, which is the member to be cut, is rotated, the stress generated when the rotary cutter contacts is
It is evenly distributed over the entire circumference of the optical fiber preform.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus according to an embodiment of the present invention will be described with reference to FIGS. The chuck 2 for gripping and fixing the optical fiber preform 1 to be cut is fixed on the base and slowly rotated by the preform drive motor 3 at a relatively slow rotation speed of up to about 20 rpm. Reference numerals 2A, 2
Reference numeral B denotes a rotation supporting device for the optical fiber preform 1, which is a means for adjusting the central axis of the optical fiber preform 1 to be exactly parallel to the rotation axis of the rotary cutter described later.

As shown in FIG. 3, the rotation supporting devices 2A and 2B are provided with two rollers 22 rotatably mounted on a Y-shaped bracket 21 mounted on a base so as to be vertically adjustable. By lowering the height of the bracket 21, the height of the optical fiber preform 1 with respect to the base surface can be adjusted.

The rotary cutter 5 and the rotary shaft having the tip fixed thereto form a cutting unit 4, which is provided in a position parallel to the optical fiber preform 1. The cutter driving motor 6 that rotationally drives the cutting unit 4 is slidably guided by the guide rods 9A and 9B so as to move integrally with the cutting unit 4 in the direction orthogonal to the rotation axis, that is, the cutting feed direction.

A diamond grinding wheel is used as the rotary cutter 5, and the rotation speed of its drive motor 6 is set to 2000 to 3000 rpm. Further, a feed screw shaft 8 is provided in the middle of the two guide rods 9A and 9B in parallel with the cutting unit 4 in order to give the cutting unit 4 a feed for cutting.

The feed screw shaft 8 is rotationally driven by a feed drive motor 7. The lead screw shaft 8 can also be rotated by a manual feed handle 10. The cutting feed speed can be adjusted within a range of about 10 mm per minute. Reference numeral 14 is a limit switch for setting the start and end of cutting of the rotary cutter 5.

When the cutting of the optical fiber preform 1 by the rotary cutter 5 is started, the rotary cutter 5 and the optical fiber preform 1
An appropriate cooling liquid is supplied to the contact point of. The cooling liquid is stored in the cooling liquid tank 11, pumped by the pump 12, and poured into the cutting position through the liquid injection pipe 13.

The optical fiber preform 1 and the rotary cutter 5 may rotate in the same direction or in opposite directions, but what is important is that the optical fiber preform 1 which is the member to be rotated rotates. That is, the stress when the cutter 5 presses the optical fiber preform 1 is dispersed in the circumferential direction. This avoids stress concentration and prevents cracks and residual stress from occurring in the base material.

[0014]

According to the present invention, since the optical fiber preform to be cut is rotated, the stress generated when the rotary cutter comes into contact with the optical fiber preform is uniformly dispersed over the outer circumference of the optical fiber preform. Since there is no concentration in one place, there is an effect that a crack, breakage, or generation of residual stress can be prevented and an efficient cutting operation can be performed.

Further, since the cutting position of the optical fiber preform is located between the rotary supporting device and the chuck, the optical fiber preform is in the form of a simple supporting beam, and bending stress can be minimized. Therefore, there is an effect that the chance of residual stress is reduced, which is extremely advantageous in terms of producing a good quality optical fiber.

[Brief description of drawings]

FIG. 1 is a plan view showing an apparatus according to an embodiment of the present invention.

FIG. 2 is a side view of the device of the present invention as seen along the axis of the optical fiber preform.

FIG. 3 is a simplified side view showing a rotation supporting device for an optical fiber preform.

FIG. 4 is a simplified perspective view for explaining the meaning of cutting both ends of the optical fiber preform.

[Explanation of symbols]

 1 Optical Fiber Base Material 2 Chuck 2A, 2B Rotation Support Device 3 Base Material Drive Motor 4 Cutting Unit 5 Rotating Cutter 6 Cutter Drive Motor 7 Feed Drive Motor 8 Feed Screw Shafts 9A, 9B Guide Rod 10 Manual Feed Handle 11 Coolant Tank 12 Pump 13 Injection pipe 14 Limit switch

Claims (2)

[Claims] 1. A step of holding and fixing the optical fiber preform (1) so that its axes are parallel to the rotary cutter (5), and the optical fiber preform (1) and the rotary cutter (5). ) And rotatably driven in the same direction or in opposite directions at an appropriate number of revolutions, and a step of feeding the optical fiber preform (1) at an appropriate cutting speed while rotating the rotary cutter (5). Method of cutting optical fiber preform. 2. A device (2) for holding and fixing an optical fiber preform (1) to be cut, and a rotation supporting device (2A) for rotatably supporting the tip of the optical fiber preform (1). A cutting unit (4) including a rotating shaft parallel to the axis of the optical fiber preform (1) and a rotating cutter (5) attached to an end of the rotating shaft and having a rotating surface orthogonal to the axis.
Cutting feed device (7, 8, 9A, 9) for feeding the cutting unit (4) in a direction orthogonal to the axis of the optical fiber preform.
B, 10) and an optical fiber preform cutting device.