JP2690465B2 - How to cut steel pipe casing - Google Patents

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 a steel pipe casing.

[0002]

2. Description of the Related Art Cables for telephone lines or power transmissions are generally bundled by a predetermined number of flexible protective pipes (for example, resin pipes) and passed through a steel pipe casing. Then, the steel pipe casing through which the cable is thus passed is directly buried in the ground, or is installed on the pedestal on the side surface of the common groove.

[0003]

However, in such a conventional technique, once the cable is passed through the steel pipe casing, it is difficult to branch and take out the cable from the middle portion of the steel pipe casing later. It was very difficult. That is, in order to branch and take out the cable inside the steel pipe casing, it is necessary to cut off a part of the steel pipe casing. May accidentally cut, so you have to carefully and carefully perform the cutting work.
It was very disadvantageous in terms of workability. Further, the method using gas cutting or arc cutting is not practical because it may melt the protective pipes and cables in the steel pipe casing at high temperatures.

The present invention has been made by paying attention to such a conventional technique, and provides a method of cutting a steel pipe casing which is easy to work and does not damage a cable in the steel pipe casing.

[0005]

In order to achieve the above-mentioned object, a method of cutting a steel pipe casing according to the present invention comprises a first rotary grinding body for grinding most of the thickness of the steel pipe casing. It comprises one step and a second step of cutting the remaining thickness portion of the steel pipe casing by a pendulum vibration type second grinding body having a smaller thickness than the first grinding body.

[0006]

With the first grinding body having a high grinding ability such as the rotary grindstone of the grinder device, rough grinding is performed to grind most of the thickness of the steel pipe casing (first step). In this first step, the portion near the inner surface of the steel pipe casing is left as it is and is not cut to the end, so there is no risk of damaging the internal cable or protective pipe, and the work is very easy. Further, since most of the thickness of the steel pipe casing is ground by the first grinding body having a high grinding ability, it is also advantageous in terms of work efficiency.

After the first step, the remaining thickness portion of the steel pipe casing is cut by a second pendulum vibration type second grinding body having a relatively low grinding performance (second step). This second grinding is of a pendulum vibration type, and although its grinding ability is lower than that of the rotary first grinding body, it has a characteristic that even if it hits a protective pipe or cable, it will not damage them. In other words, since the second grinding body is a pendulum vibration type with a small width, although a rigid body such as a steel pipe casing is ground, in the case of a relatively soft flexible material such as resin or rubber, those flexible materials are Since it vibrates together with the second grinding body, it is difficult to grind. Therefore, the worker can work with the second grinding body without worrying about damaging the cable or the protective pipe, which is very advantageous in terms of workability. Also,
The second grinding body has a smaller thickness than the first grinding body,
Since the second grinding body does not hit the side surface of the excavation groove formed by the first grinding body, workability in the second step is improved also in this respect. Further, this second ground body does not damage human skin even if it hits it, which is preferable in terms of safety.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described with reference to FIGS.
It will be described based on. 1 is a steel pipe casing with an inner diameter of 3
It has a size of 00 mm and a wall thickness of 8 mm. Seven protective pipes 2 made of resin are housed in the steel pipe casing 1. A plurality of telephone line cables K are passed through each protection pipe 2 in a bundled state (see FIGS. 3 and 4).

Then, in order to branch and take out the cable K in the steel pipe casing 1, a part of the steel pipe casing 1 is provided with two cutting lines 3a and 3b along the circumferential direction and between the cutting lines 3a and 3b. Two cutting lines 4a and 4b along the longitudinal direction are set at opposing positions (see FIG. 1).

As the work, first, the cutting line 3 along the circumferential direction
Each of a and 3b was cut, and then cutting lines 4a and 4b along the longitudinal direction were cut, and the cut portions were removed to expose the internal protective pipe 2 (see FIG. 2). By cutting the cutting lines 3a and 3b along the circumferential direction, the cylindrical portion between the cutting lines 3a and 3b can freely rotate in the circumferential direction. Therefore, when cutting the cutting lines 4a and 4b in the longitudinal direction. In this case, the cutting work may be performed after the cutting lines 4a and 4b are located at the position where the work is most easy (for example, the upper part).
If a part of the steel pipe casing 1 is partially opened in this way, the protection pipe 2 is made of resin, so that it can be easily cut and the telephone line cable K inside can be branched.

Next, the above-mentioned cutting lines 3a, 3b, 4a, 4
A specific cutting method of b will be described. The above cutting lines 3a, 3b, 4a, 4b are cut by the grinder device 5
And two cutting tools of the cutter device 6 were used. The grinder device 5 has a disk-shaped rotary grindstone (first grinding body) 7 that rotates at high speed at the tip, and the cutter device 6 has grinding teeth (second grinding body) 8 that vibrates pendulum with a minute width at the tip.
It has. The rotary grindstone 7 of the grinder device 5 has a large thickness D and a high grinding performance for the steel pipe casing 1. Since the grinding teeth 8 of the cutter device 6 have a small thickness d and only vibrate with a pendulum having a minute width, the grinding performance for the steel pipe casing 1 is relatively low. However, this grinding tooth 8
A material such as resin, rubber, or human skin that is softer than metal and that can vibrate with a minute vibration width of the pendulum vibration is relatively difficult to cut and scratch.

Therefore, as shown in FIG. 3, as a first step, most of the thickness of the steel pipe casing 1 is ground by the rotary grindstone 7 of the grinder device 5. Specifically, the grinding groove 1a is formed by grinding about 6 to 7 mm of the thickness of 8 mm.
Is formed, and the last portion 1b of about 1 to 2 mm is left without being cut. In the first step using the rotary grindstone 7, since the grinding ability of the rotary grindstone 7 is high, the time is short, and since it is not cut to the end, the internal protection pipe 2 is not likely to be damaged and the work is very easy. is there.

Then, the portion 1b left in the first step
Is cut by a pendulum vibration type grinding tooth 8 as a second step. Although the pendulum vibration type grinding tooth 8 has a relatively low grinding ability, the remaining portion 1b is thin, so that cutting of this portion does not take much time. Further, since the protection pipe 2 is in close contact with the inner surface of the steel pipe casing 1, the grinding teeth 8 come into contact with the protection pipe 2 when cutting the remaining portion 1b, but a relatively soft material such as resin is As described above, it is not damaged by the grinding teeth 8.
Therefore, even in the second step by the cutter device 6, the worker does not have to damage the protection pipe 2 inside, and the work can be performed very easily. Further, since the thickness d of the grinding tooth 8 is smaller than the thickness D of the rotary grindstone 7 and the side surface of the grinding tooth 8 does not contact the side surface of the excavation groove 1a formed by the rotary grindstone 7, also in this respect, the second step Improves workability.

As described above, according to the present invention, the protection pipe 2 in the steel pipe casing 1 is used in both the first step and the second step.
Since there is no danger of damaging the work, there is no need to perform the work carefully and carefully, which is very advantageous in terms of workability. Also,
Since most of the thickness of the steel pipe casing 1 is performed by the rotary grindstone 7 having high grinding ability, the time required for cutting work can be shortened.

In the above embodiment, two cutting lines 3a and 3b along the circumferential direction and two cutting lines 4a and 4b along the longitudinal direction are set, but the present invention is not limited to this. Instead, any cutting line may be set as long as the protection pipe 2 inside can be exposed by opening a part of the steel pipe casing 1.

Of the two cutting lines 4a and 4b in the longitudinal direction, one cutting line 4a is cut in the first step and the second step, and the other cutting line 4b is the excavation groove 1a formed in the first step. Alternatively, the cutting line 4a, which has been cut, may be pushed open by a hydraulic device or the like, and the protective pipe 2 may be pulled out from the opened portion. At this time, since most of the other cutting line 4b is the excavation groove 1a, the push-opening operation of the one cutting line 4a can be easily performed with a small force.

Further, in the above-mentioned embodiment, the steel pipe casing 1 is provided with the cables K such as telephone lines bundled by the protection pipe 2.
Although the example in which the cable K is passed through the inside is shown, the present invention can be applied to the case where the cable K such as a telephone line is directly passed through the steel pipe casing 1 without using the protection pipe 2.

[0018]

The method for cutting a steel pipe casing according to the present invention has the contents described above, and neither the first step nor the second step has a risk of damaging the protective pipe or the like in the steel pipe casing. It is very advantageous in terms of workability because it does not require careful and careful work. Also,
Since most of the thickness of the steel pipe casing is performed by the rotary first grinding body having high grinding performance, the time required for cutting work can be shortened.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a steel pipe casing according to an embodiment of the present invention.

FIG. 2 is a view showing a state where a steel pipe casing is partially opened.
It is a considerable perspective view.

3 is a cross-sectional view taken along the line SA-SA shown in FIG.

FIG. 4 is a sectional view corresponding to FIG. 3, showing a state in which a cutting line is completely cut.

[Explanation of symbols]

 1 Steel Pipe Casing 2 Protective Pipe 7 Rotating Wheel (First Grinding Body) 8 Grinding Teeth (Second Grinding Body) K Cable

Claims (3)

(57) [Claims] 1. A method of cutting a steel pipe casing in which a cable is bundled by a flexible protective pipe and passed through the inside, wherein most of the thickness of the steel pipe casing is ground by a rotary first grinding body. And a second step of cutting the remaining thickness portion of the steel pipe casing with a second grinding body of a pendulum vibration type having a smaller thickness than the first grinding body. . 2. A method of cutting a steel pipe casing in which a cable is passed inside, the first step of grinding a large part of the thickness of the steel pipe casing with a rotary first grinding body, and a pendulum vibration method. A method of cutting a steel pipe casing, comprising a second step of cutting a remaining thickness portion of the steel pipe casing with a second grinding body having a smaller thickness than the first grinding body. 3. The steel pipe according to claim 1 or 2, wherein a pair of cutting lines extending along the circumferential direction is set on the steel pipe casing, and a pair of cutting lines extending along the longitudinal direction is set at opposing positions between the cutting lines. How to cut the casing.