JPH0215318B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for repairing defects in aluminum tubes that house optical fibers in, for example, power-optical composite cables.

(Prior Art) This type of aluminum pipe needs to be manufactured continuously for 1000 to 3000 m.

Traditionally, the manufacturing of aluminum tubes containing optical fibers was carried out at the 7th
As shown in the figure and FIG. 8, the optical fiber 4 is supplied from the tape supply 1 in a state housed in the groove 6 of the aluminum spacer 5, and the optical fiber 4 is vertically attached to the center of the upper surface of the aluminum tape 2' and formed. Process 7
The aluminum tape 2' is pipe-formed so as to incorporate the spacer 5 containing the optical fiber 4, and then the seam part 9 of the formed aluminum pipe 2 is welded in the welding step 8, and then after cooling. In the diameter reduction step 10, the aluminum tube 2 is reduced in diameter to a required size, work-hardened, and then wound up with a winder 11. In this case, if the aluminum pipe has a defective part 13 such as a pinhole in the welded part 12, water will enter through the defective part 13, so even one pinhole will result in a defective product.

Conventionally, defects in the aluminum tube 2 have been repaired by thermal means such as electric welding or aluminum soldering, or by adhesive.

(Problem to be Solved by the Invention) However, in the case of repair by thermal means, for example, if the diameter of the aluminum tube 2 that accommodates the optical fiber 4 is small, the entire tube in the repaired portion will be annealed and the aluminum tube will be annealed. There is a problem that the mechanical strength of the tube 2 is reduced. On the other hand, in the case of repair using adhesive, there is a problem that the repaired part lacks thermal strength and the repaired part easily peels off due to vibration.

The purpose of the present invention is to suppress the decrease in mechanical strength,
Another object of the present invention is to provide a method for repairing defects in aluminum pipes that does not reduce the reliability of repaired parts due to heat, vibration, etc.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides that when repairing a defective part of an aluminum tube by laser welding, the laser discards the first few pulses and performs a welding process at each pulse. The feature is that the repair is performed by overlapping the parts by 50% or more.

(Function) When performing repairs in this manner, by discarding the first few pulses of the laser pulse, stable repairs can be performed using stable laser pulses. Furthermore, since repairs are performed by overlapping the welding location by 50% or more with each laser pulse, it is possible to use a location where the laser heat is stable, resulting in uniform penetration.

(Example) Examples of the present invention will be described below with reference to FIGS. 1 to 3. In this embodiment, when repairing the defective part 13 of the aluminum tube 2 as shown in FIG.
Uses YAG laser. When this laser energy is irradiated continuously, the energy is not stable for the first few pulses and has large fluctuations as shown in FIG. Therefore, when repairing a defective part 13 such as a pinhole using a laser, the penetration 14 of the defective part 13 performed pulse by pulse may be too small or too large as shown in FIG. As shown in FIG. 5, if the proper penetration is small, it will easily break, and if it is large, holes will form and the optical fiber will be thermally damaged. Therefore, in the present invention, when repairing the defective portion 13 of the aluminum tube 2, the first few pulses of the continuous pulse output of the laser are avoided, and the laser pulse 15 is injected at 50% every pulse after the pulse becomes stable. This is done by overlapping the laser pulses by more than % and using a stable heat area on the center side of the laser pulse 15 to obtain a certain level of penetration.

At this time, the aluminum tube 2 is fixed to a holder 16 as shown in FIG. 6, and the defective portion 13 is irradiated with a laser pulse 15 from the laser welding machine 17. The holder 16 is fixed to a moving table 18, and the moving table 18 is provided on a position adjustment table 19. The position adjustment table 19 is used to align the direction of the crack in the defective portion 13 with the direction of movement of the moving table 18. When the direction of the crack in the defective portion 13 matches the moving direction of the moving table 18, laser welding is performed by synchronizing the laser irradiation and driving of the moving table 18 so that the laser pulses 15 overlap by 50% or more.

(Effects of the Invention) As explained above, in the present invention, when repairing a weld defect using a laser, the first few pulses are discarded and the laser welding is performed, so stable laser pulses are used to weld the repair. It can be done by
In addition, the laser pulse cuts 50 welding points per pulse.
Since the repair is performed with an overlap of more than %, the repair can be performed using the stable heat area on the center side of the laser pulse to obtain a certain level of penetration. Therefore, according to the present invention, defective portions of aluminum tubes can be repaired stably and efficiently.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of the state of repair according to the present invention, Fig. 2 is a side view showing an example of a defective part of an aluminum tube, Fig. 3 is a plot diagram showing the energy level of the laser pulse, and Fig. 4 5 is an enlarged cross-sectional view showing a defective repair state and a normal repair state of the welded part, FIG. 6 is a side view showing an example of the repair state of the aluminum pipe in this example, and FIG. 7 is an optical FIG. 8 is a process diagram showing an example of the manufacturing process of the fiber-filled aluminum tube, and a cross-sectional view showing an example of the optical fiber-filled aluminum tube. 2... Aluminum pipe, 12... Welded part, 13... Defective part,
15...Laser pulse.

Claims (1)

[Claims] 1. Defect repair of aluminum pipes, which is characterized in that when repairing defective parts of aluminum pipes by laser welding, the first few pulses of the laser are discarded, and the repair is carried out by overlapping the welding part by 50% or more for each pulse. Method.