JPH01255412A - Method of laying cable - Google Patents

Abstract

PURPOSE:To lay a cable without causing a sag of the cable, by selecting torque characteristics of a tracting machine on the side of the top and of ones on the side of the rear, and by setting the maximum tracting force of the tracting machine on the side of the rear lower than the load the machine is to bear. CONSTITUTION:The cable 1 to be laid is wound around a drum 2, at the tip of which a rope 6 is bound. In order to lay the cable 1, a tracting machine M2 at the tip and one M1 on the rear are provided. The tracting machine M2 tracts the rope 6 and winds it with a winder 7. The tracting machine M1 on the rear tracts the cable 1 in the section S1. The maximum torque of the tracting machine M1 on the rear is set lower than the torque necessary for tracting the cable 1. The torque in shortage is to be borne by the tracting machine M2 at the tip. The traction and stoppage of traction is performed only by the control of the tracting machine M2 at the tip, so that no sag of cable will be caused.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a cable laying method suitable for laying long cables such as optical fiber cables.

(Technical background of the invention and its problems) When laying a cable inside a conduit or a tunnel, a winch or an endless belt-type traction device is used.

In particular, long lengths such as optical fiber cables, etc.
Conventionally, for cables that must be prevented from being subjected to abnormal tension during installation, the following installation method has been adopted.

FIG. 5 is a schematic diagram showing an example of a conventional cable installation method.

In the figure, cable l is wound around drum 2,
It is pulled out from its tip 3 and installed in a conduit or the like.

Here, at the time of starting the installation of the cable l, the distal end portion 3 of the cable l is first pulled out by one traction device M3. After that, when the length of the cable l becomes longer, as shown in FIG. , for example two intermediate traction machines M2. Install M3. This intermediate traction machine M2. For M3, cable 1
It will be installed in a suitable manhole etc. in the section where the cable will be laid.

and each intermediate traction machine M2. M3 is provided to feed out the cable l in the direction of the arrow 4 in conjunction with the tip traction machine Ml. In addition, each intermediate traction machine M2. A slack detector is arranged in front of each M3. As a result, each intermediate traction machine M2. When the traction force from the other traction machine works in front of M3 and the slack in cable 1 is removed,
Start sending out cable l. On the other hand, when no traction force is acting in front of the cable 1, a certain amount of slack occurs in the cable 1, so each of the intermediate traction machines M2 and M3 detects this and stops feeding out the cable 1.

As described above, according to the installation method shown in FIG. 5, it is possible to drive a plurality of independently installed traction devices in synchronization with each other while creating a certain range of slack in the cable l. .

Therefore, this method has the advantage that there is no need to run separate control lines etc. in order to synchronize each traction device with each other. However, the provision of a sag detector complicates the mechanism, and the setting of operating conditions becomes complicated.

Apart from this, there is also known a method which is similar to the method shown in FIG. 5 in that it is a speed follow-up type, but which performs constant torque type control.

In this method, each traction device as shown in FIG. 5 is set so as to send out the cable with a traction force of a constant torque.

In this case, no slack detection device is used. In other words, once cable installation using this method is started, the traction device will always rotate with the set constant torque even if the load fluctuates due to the condition of the conduit, the condition of the cable, the frictional force of the cable, etc. do.

Therefore, if the load is less than the set torque, the traction device continues to feed out the cable, and if the load exceeds the set torque, the traction device stops feeding out the cable.

However, with this method, if the load is sufficiently smaller than the set torque, the cable will be fed out beyond the amount of cable fed out by the traction device installed in front, causing abnormal slack in the cable and causing buckling. There is a risk of causing On the other hand, if the load exceeds the set torque, the traction device will stop, which will act as a brake and apply a load to the front traction device, adversely affecting the cable in front and slowing down the entire installation process. Disturb the harmony. When such a phenomenon occurs, the operator is required to constantly readjust the traction force of each traction device to an appropriate value. However, this type of operation requires considerable skill and has the drawback of requiring mastery of techniques for responding to various changes in external conditions.

(Object of the Invention) The present invention has been made with attention to the above points, and can further automate and save labor in laying long cables.
Furthermore, it is an object of the present invention to provide a cable installation method that does not require sensors such as slack detectors or control lines. Another object of the present invention is to provide a cable laying method that can prevent unnecessary slack from occurring in the cable when the cable is being pulled and can smoothly pull the cable.

(Summary of the Invention) The cable installation method of the present invention uses at least two traction machines, a tip-side traction machine installed at the front end of the cable, and a rear-side traction machine installed behind it. In the case of towing and laying, the torque characteristics of each of the above-mentioned traction machines are set so that the traction force gradually decreases as the traction speed increases, at least in a steady operating range near the maximum traction speed (traction speed under no load). and the torque characteristics of the front side traction machine and the rear side traction machine are set such that the maximum traction speed of the front side traction machine exceeds the maximum traction speed of the rear side traction machine, and the rear side traction machine is The maximum traction force of the machine is set to be a predetermined amount lower than the load to be borne, while the traction force of the tip side traction machine is set to a traction force higher than the load to be borne by at least the predetermined amount. It is characterized by this.

(Example of the invention) Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 is an explanatory diagram of the operation of a traction machine when the cable laying method of the present invention is implemented.

Before this explanation, a schematic configuration of a system implementing the present invention will be explained.

FIG. 2 is a schematic diagram of an installation system implementing the method of the invention.

In the figure, a cable 1 to be laid is wound around a drum 2, and a lobe 6 is tied to the tip of the cable 1. In order to lay this cable 1 in this section, two endless belt type traction machines Ml and M2 are installed. In this figure, the traction machine M1 on the side closer to the drum 2 will be referred to as the rear traction machine M1, and the traction machine M2 located toward the distal end of the cable 1 will be referred to as the distal traction machine M2.

In this figure, a tip-side pulling machine M2 pulls the lobe 6, and the lobe 6 is wound up on a winding machine 7.

In this system, as shown in the figure, the rear traction machine Ml pulls the cable 1 in the section S1, and the front traction machine M1 pulls the cable 1 in the section S1.
2 pulls the cable 1 and lobe 6 in section s2. In this case, the force required for the rear traction machine Ml to pull the cable 1 in this section St is set as ft. In addition, let f2 be the force required for the tip side traction machine M2 to pull the cable 1 etc. in the section S2, and actually the rear side traction machine M2.
Let F 1 be the traction force when the tip side traction machine M2 is operating.

Incidentally, in the system shown in FIG. 2, each towing machine is equipped with a control device as shown in FIG. 3.

In FIG. 3, an endless belt 1o of a traction machine that pinches and pulls a cable 1 is connected to a motor 1 via a decelerator 11.
It is driven by 2. A speed sensor 13 is attached to the rotating shaft of the motor 12 to detect its traction speed.

Furthermore, in order to detect the actual pulling speed of the cable 1,
A speed sensor 14 is attached.

Further, in order to drive this motor 12, a power supply circuit 15 and a control circuit 30 are provided. The power supply circuit 15 includes a rectifier 17 that rectifies a commercial power supply 16, a power unit 18 that is controlled by a control circuit 30 and supplies a predetermined drive power to the motor 12, and a current limiter that limits the supplied current.
19, a current sensor 20 that monitors the supplied current, and a brake unit 21 that is used to apply a brake to the motor 12.

The control circuit 30 also includes a CPU that controls the operation of the entire device.
(microprocessor) 31, ROM (read-only memory) 32, setting switch 33 for manually inputting instructions for operation control, D/A converter 34, and A/A converter 34.
D converter 35 and two pulse counters 36, 37
It is composed of.

This device is for controlling the traction machine to operate with predetermined torque characteristics, which will be explained later in FIG. is driven.

The microprocessor 31 detects the rotational speed of the motor 12 by counting the output signal of the speed sensor 13 with a pulse counter 36. Further, the actual running speed of the cable is detected by counting the detection signal of the speed sensor 14 with a pulse counter 37.

Further, the current supplied to the motor 12 detected by the current sensor 20 is converted into a digital signal via the A/D converter 35 and is input into the microprocessor 31 . or,
Based on this information, the microprocessor 31 calculates the drive current and voltage of the motor 12, and the D/A converter 3
4 to control the power unit 18. As described above, the power unit 18 supplies a predetermined drive voltage and drive current to the motor 12 under its control. Here, the current limiter 19 is a circuit that limits the maximum output current of the power unit 18 in order to maintain the maximum tractive force previously set by the setting switch 33.

Now, in the method of the present invention, first, each traction machine, that is, the rear traction machine Ml and the front traction machine M2 shown in FIG.
The torque characteristics of are set as shown in FIG. In this graph, the horizontal axis shows the traction speed of the towing machine, and the vertical axis shows the traction force. As described above, the torque characteristics of any of the traction machines are set so that the traction force gradually decreases as the traction speed increases, at least in the steady operation range 40 near the maximum traction speed V MAX. In reality, for example, in the case of a DC shunt motor, it exhibits a linear torque characteristic as shown by the broken line in the figure, which has a negative slope toward the maximum traction speed V WAX.

When implementing the method of the present invention, a maximum traction force F MAX is also set for each traction machine. This is the third
This is based on the action of the current limiter 19 shown in the figure. As a result, the traction machine operates within the operating range shown by the hatching in the figure. Note that the maximum traction speed V WAX corresponds to the traction speed of this traction machine when no load is applied.

Now, returning to FIG. 1, the torque characteristics and operations of the leading-side traction machine and the rear-side traction machine will be explained in more detail.

Similarly to FIG. 4, FIG. 1 is a graph in which the horizontal axis represents the traction speed and the vertical axis represents the traction force. It goes without saying that this traction speed is proportional to the driving voltage of the motor, and the traction force is proportional to the driving current of the motor.

When carrying out the method of the present invention, as shown in FIG. 1, the torque characteristic of the rear traction machine is set in advance to Ll, and the torque characteristic of the front traction machine is set to L2. In this embodiment, the slopes of the torque characteristics of both traction machines are almost parallel, and the maximum traction speed VZMAX of the leading traction machine is set to exceed the maximum traction speed VlklAX of the rear traction machine (first Figure■
) is set to a value of about 0.5 m per minute, for example. The maximum traction speed V211AX of the tip side traction machine is, for example, 20 m/min. In the present invention, both traction machines are normally driven in a steady operating range 40 as indicated by the arrows in the figure. This steady operation range is, for example, ten meters per minute.

By the way, as shown in FIG. 2, the rear side traction machine M1 and the front side traction machine M2 work in conjunction with each other to pull the cable 1 etc. at the same traction speed. In this example,
As shown in the figure, in the steady operation range 40, the tip side traction machine M2
When the rear-end traction machine M1 and the front-end traction machine are driven at the same speed, the traction force of the front-end traction machine is set to exceed the traction force of the rear-side traction machine.

On the other hand, as shown in FIG. 2, the load borne by the rear traction machine M1 is f1, and the load borne by the front traction machine M2 is f2. On the other hand, the initial maximum traction force of the rear traction machine M1 is set in advance to the value A shown in FIG. 1 (FIG. 1). That is, the rear traction machine is initially set so that its maximum traction force is limited to a value A lower by α than the load f+ to be borne by the rear traction machine. This traction force is, for example, about 160 kg. On the other hand, the maximum traction force of the tip side traction machine is set to H. This traction force H is, for example, approximately 200 kg. This value is the maximum allowable value for the cable and is also the upper limit for the rear traction machine. Note that a value of 0 for a weight of 10 kg is actually appropriate for the above a.

When the above settings are made, first of all, in the system shown in Figure 2, the rear traction force I M1 is set to a maximum traction force that is lower than the load f + that should be borne by the user. , cannot initiate the traction of the cable 1 by itself.

Therefore, the cable 1 will not be towed unless the tip-side traction machine M2 starts towing.

Here, the value where the traction force of the tip side traction machine exceeds f2+α,
For example, it is set to C and traction is started (■ in Figure 1). As a result, as shown in FIG. 1, the tip-side traction machine compensates for the insufficient traction force α of the rear-side traction machine, and traction of the cable l is started. Thereafter, the tip side traction machine M2 gradually increases the traction speed while increasing the traction force as shown by the arrow ■, and reaches the steady operation range 40 described above.

Meanwhile, at the same time, as shown in FIG. Here, the traction speed of both traction machines becomes VR. In this state, the tractive force F1 of the rear traction machine is lower by Δf than the load f+ that the rear traction machine should actually bear. Therefore, the tip side traction machine M2 uses this △f
In order to compensate for this, the distal end side traction machine is driven with a traction force F2 obtained by adding Δf to the load f2 that it should originally bear. In this state, the cable 1 and the lobe 3 are towed at a steady speed by the rear traction machine Ml and the front traction machine M2, respectively.

In addition, it is preferable that the above-mentioned Δf is specifically set to a value of 0 for a weight of 15 kg. Moreover, after the rear traction machine reaches this steady operation range 40, its maximum traction force is F+ +
Lower the value of a slightly (Fig. 1 ■). This value is
For example, the weight is 150 kg. In this way, when being towed in a steady state, each towing machine operates as shown by the arrow in the figure along the torque characteristics within its steady operating range 40.

Next, if some obstacle occurs during towing, or if the installation of the cable 1 is completed, the tip traction machine M2 stops. In this case, the traction speed of the rear traction machine M1 also decreases and the load increases rapidly. Therefore, the traction speed of the rear traction machine decreases along the route shown by the arrow in FIG. The towing speed of this towing machine is set to V in advance. If conditions are set to apply the emergency brake when the temperature drops to a certain level, the rear towing machine Ml will automatically stop.

As explained above, if the torque characteristics of the front traction machine and the rear traction machine are set separately as explained above, and these two traction machines are operated in conjunction, the traction of both Since the speeds are forced to be the same, the traction force of the rear traction machine decreases by △f, and the traction force of the front traction machine decreases by △f.
The traction force increases to compensate for the traction force of f, which allows the cable to be pulled. In addition, if the upper limit of the traction force of the rear traction machine is set appropriately, when the tip traction machine stops towing, the rear traction machine will immediately reduce its traction speed and stop automatically, which will prevent excessive stress on the cable. No traction force is applied. Also, no abnormal cable slack occurs.

The present invention is not limited to the above embodiments.

In the above embodiment, an example was shown in which the cable is pulled by two traction machines, the front traction machine and the rear traction machine.
Even if there are three or more traction machines, if the relationship between the leading traction machine and the rear traction machine is set as described above, all of them can be controlled in the same way. Therefore, set multiple towing machines in order in the relationship explained above,
It is possible to control these traction machines in conjunction without using control lines or slack detectors.

(Effects of the Invention) According to the cable installation method of the present invention described above, the torque characteristics of the leading end traction machine and the rear traction machine are appropriately selected,
Since the maximum traction force of the rear traction machine is set to be a predetermined amount lower than the load that it should bear, the rear traction machine cannot pull the cable independently, and the cable is pulled at the same time as the front traction machine starts towing. Start towing and stop towing at the same time as the tip side towing machine stops. As a result, a plurality of traction machines can be controlled in conjunction with each other, and cable installation work can be carried out without causing unnecessary slack in the cable.

[Brief explanation of the drawing]

Fig. 1 is an operational explanatory diagram explaining the cable laying method of the present invention, Fig. 2 is a schematic diagram of a cable laying system implementing the method of the present invention, and Fig. 3 is a block diagram showing an embodiment of the control device for the traction machine. Figure 4 is an explanatory diagram of the torque characteristics of the traction machine, Figure 5
The figure is an explanatory diagram of a conventional cable installation system. l-111 cable, 2-111 drum, 6---- lobe, 7---- winder, Ml-m-rear side traction machine, M2-m-tip side traction machine, vvAx - - Maximum traction speed, f+-m-Load to be borne by the rear traction machine, f2-
m - Load to be borne by the tip side traction machine. (1 other person) Figure 4\ゝ, Figure 5

Claims (1)

[Claims] In the case where the cable is towed and laid using at least two traction machines, a tip-side traction machine installed on the tip side of the cable and a rear-side traction machine installed on the rear side thereof, each of the traction machines: The torque characteristic is set so that the traction force gradually decreases as the traction speed increases, at least in a steady operating range near the maximum traction speed (traction speed under no load),
The torque characteristics of the tip side traction machine and the rear side traction machine,
The maximum traction speed of the tip side traction machine is set to exceed the maximum traction speed of the rear side traction machine, and the maximum traction force of the rear side traction machine is set to be lower than the load to be borne by a predetermined amount. On the other hand, the cable laying method is characterized in that the traction force of the tip side traction machine is set to a traction force that is higher than the load to be borne by the predetermined amount or more and is driven.