JPS5810254Y2 - Continuous cable crosslinking equipment - Google Patents

Description

[Detailed description of the invention] This invention is an improvement of a device that continuously heats and crosslinks uncrosslinked materials such as rubber and plastic that make up the insulation and sheath covering the cable core wire in a crosslinking pipe. It is related to.

Generally, this type of device includes a pump c, a supply pipe d, an overflow pipe e, a tank b, which carries a crosslinked heat medium a such as molten salt heated to a predetermined temperature, as shown in FIG.
For example, an uncrosslinked insulator is coated from a crosshead g of an extruder (not shown) provided at one end of the crosslinked pipe f into the crosslinked pipe f. After the uncrosslinked cable h is inserted and the uncrosslinked object is heated and crosslinked by the crosslinking heat medium a, it is passed from the other end of the crosslinked pipe f through the guide 1 to the next cooling device (not shown). )
I'm trying to send it to.

At this time, in order to prevent the surface of the uncrosslinked coating, which still has poor mechanical strength, from coming into contact with the inner surface of the crosslinked pipe f and being damaged or deformed, conventional methods have been used to prevent the entire length of the crosslinked pipe f from being damaged or deformed. is formed into a catenary shape as shown in the figure, and the cable h is also inserted through the bridge pipe f while being controlled to maintain the corresponding catenary.

However, the control accuracy for maintaining the cable h in a predetermined catenary must be increased in direct proportion to the square of the length of the cable h whose catenary is to be maintained.

To explain in more detail, the approximation formula for the catenary curve is It is expressed as

In this formula, X is the crosshead g of the extruder in Figure 1.
The horizontal straight line length of the cable h connecting the two points, y and the central lower part of the bridge pipe f, y is the vertical straight line length, and C represents a catenary constant number.

Therefore, when we actually calculate the error rate of the permissible vertical displacement at the central low part of the cable h using the above formula, we find that c=
200 m, the inner diameter of the bridge pipe f is 100 m, and the above allowable vertical displacement is ±50 mHx = 15 m, then y =, 0.5625 m y (maximum) = 0.5625 + 0.05 = 0
．． 6125 my (minimum) - 0,5625 - 0,05 =
0.5125 m, and then when x = 30 m, it becomes.

As a result of the above calculation, the value of y is considerably smaller than the value of X, so it is safe to regard the value of X as the length of cable h,
Therefore, doubling the length of X, that is, the length of cable h, will reduce the allowable error rate to 1/4, which will quadruple the control accuracy for maintaining cable h in the allowable catenary shape. must be increased to

For this reason, if the entire length of the bridge pipe f is catenary-shaped as described above, the cable h must be maintained in a catenary over a considerable length, which requires higher control accuracy, which reduces the economic efficiency of the equipment. This is extremely disadvantageous in terms of productivity.

In view of these conventional problems, the present invention was developed by considering the preconception that the entire length of the bridge pipe must be shaped like a catenary.As a result, the cable inserted into the bridge pipe from the entrance side is At the initial stage, a surface cross-linked film is formed on the coating, resulting in a so-called skin cure state, which improves the mechanical properties of the surface layer. By focusing on the fact that the pipe does not bend or deform, and by making only a part of the bridge pipe into a catenary type, it is no longer necessary to control the cables that pass through it as highly as in the past. The aim is to improve equipment economy and productivity.

Here, the surface crosslinked membrane is defined as a layer in which the properties such as the tensile modulus and gel fraction of the insulating coating and sheath up to 0.2 degrees thick from the surface of the cable are at a level ranging from the uncrosslinked level to the optimal crosslinked level. It means that it has reached 50% or more.

This configuration will be explained below based on an embodiment shown in FIG. 2. In the figure, 1 is a crosshead part of an extruder (not shown) that extrudes and coats the cable core with uncrosslinked insulation;
2 is a cross-linked pipe whose one end is connected to the crosshead section 1 and the other end is connected to a cooling device (not shown); 3 is a tank for storing a cross-linked heat medium such as heated molten salt; and 4 is the tank. A pump 6 is connected near both ends of the cross-linked pipe 2 to supply the cross-linked heat medium in the pipe 2 to the cross-linked pipe 2 from its lowest point through the feed pipe 5, and supplies the cross-linked heat medium in the pipe 2 to the tank 3 This is an overflow pipe that returns to the inside, and the structure of these pipes is the same as the conventional one.

In such a continuous crosslinking device, the present invention provides a predetermined crosslinking process for at least a portion of the crosslinked pipe 2 from the crosshead portion 1 to a position where a surface crosslinking film is formed on the sheathing of the insulated cable A inserted. The catenary shape is formed along the catenary line, and the other parts are formed in any shape other than the catenary.In the embodiment shown in FIG. The left part of the center is shaped like a catenary, and the right part is shaped like a straight tube that slopes upward toward the right in the figure, so that the image part is continuous in the center.

Therefore, in order to crosslink the coating of an insulated cable using the continuous crosslinking device according to this embodiment, the heated crosslinking heat medium in the tank 3 is brought to a predetermined temperature via the pump 4, the feed pipe 5 and the overflow pipe 6. At the same time, the insulated cable A whose cable core wire is coated with an uncrosslinked insulator is passed through the crosshead 1 into the crosslinked pipe 2 by an extruder, and then passed through the crosslinked pipe 2. It is sent to the next cooling device via a guide 7 provided on the side of the cooling device.

At this time, the insulated cable A only needs to maintain a corresponding catenary in the catenary-shaped portion of the bridge pipe 2, and control the insulated cable A so that the sheath does not come into contact with the inner surface of the bridge pipe 2. Insertion is performed while ignoring contact at other straight portions of the bridge pipe 2.

In this way, the sheathing of the insulated cable A is heated by the crosslinking heating medium during the process of being inserted into the crosslinked pipe 1, and the entire sheath is crosslinked, but the surface layer of the sheathing has already been crosslinked in the catenary-shaped portion. A surface crosslinked film is formed,
Since it is in a so-called skin-cured state, even if it comes into contact with the inner surface of the cross-linked pipe 2 in the latter half straight portion, it will not be damaged or deformed.

However, according to experiments conducted by the present inventors regarding this point, the above-mentioned surface crosslinked film is formed on the coating of the insulated cable A because the insulated cable A is in the crosslinked pipe 2 and contains the crosslinked heating medium. It has been confirmed that the stage reaches approximately one quarter of the entrance side of the section.

Therefore, even in the case of the above-mentioned embodiment in which half of the total length of the bridge pipe 2 is made into a catenary shape and the sheathing of the insulated cable A is controlled so as not to come into contact with the inner surface during this period, damage to the sheathing cannot be completely prevented. The length of the insulated cable A that can be made and maintain the specified catenary at this time is:
Since only half the length of the cable A existing in the bridge pipe 2 is sufficient, the control accuracy for it is one-fourth of that of the conventional method.
(4 times the allowable error).

In the embodiment shown in FIG. 2, the central portion of the cross-linked pipe 2 is set to be the lowest position in order to circulate the cross-linked heat medium within the pipe 2 in the same manner.

Further, the shape of the part of the intermediate pipe 2 that is not catenary-shaped is not particularly limited as long as it can circulate the cross-linked heat medium therein and the insulated cable A can be inserted therein. In addition to the straight pipe shape, any shape can be adopted.

Also, the crosslinked pipe 2 does not necessarily need to be used together with an extruder,
A cable whose cable core wire is coated with an uncrosslinked material may be supplied into the crosslinked pipe 2 and crosslinked in a separate step.

Further, the uncrosslinked objects to be crosslinked with the apparatus of the present invention are not limited to the above-mentioned insulators, but also include crosslinkable conductive layers and sheaths coated on cable cores.

As explained above, in the present invention, there is a cross-linked pipe in which only the cross-linked heat medium is housed throughout, and only the surface cross-linked film is coated on the cable A inserted from at least the inlet side of the cross-linked pipe 2. The part before it is formed is made into a catenary shape, and the cable A is controlled so that it has the same catenary shape only during that period, so the sheathing of the cable A is not damaged or deformed, and the control accuracy is improved compared to the conventional one. Therefore, it is expected that not only equipment economy will be improved but also productivity will be improved.

Furthermore, the parts of the bridge pipe 2 that are not catenary-shaped can be formed into any shape, such as a straight line, so the design and manufacturing of the bridge pipe 2 is much easier than in the conventional case where the entire structure is catenary-shaped. This makes it possible to provide a continuous crosslinking device that is extremely advantageous in terms of equipment economy.

[Brief explanation of drawings]

FIG. 1 is a implied vertical side view showing a conventional example of a continuous cable bridging device, and FIG. 2 is a implied vertical side view showing an embodiment of the present invention. 2...Bridge pipe, A...Insulated cable.

Claims (1)

[Scope of utility model registration request] In a continuous cross-linking device in which a cable coated with an uncross-linked material such as rubber or plastic is inserted into a cross-linked pipe in which only a cross-linked heating medium is housed throughout, and the cable is heated and cross-linked, one of the cross-linked pipes is , at least the part before the position where only the surface cross-linked membrane is formed on the cable sheath inserted from the entrance side is made into a catenary shape along a predetermined catenary line, and the other part is made into any shape other than catenary. Continuous cross-linking device for cables formed by forming.