JPH0531183U - Mold for insulator molding of power cable connection - Google Patents

Abstract

(57) [Summary] [Structure] The upper mold 31A and the lower mold 31B are divided into three blocks 31A1 to 31A3 and 31B1 to 31B3 in the longitudinal direction. On the resin molding surface P of each block, a hard chrome plating film with tetrafluoroethylene resin embedded in minute cracks.
Set up 39. A chamfered portion R is formed at a corner portion between the resin molding surface P and the divided surface Q of each block, and a hard chrome plating film 39 is also provided there. [Effect] It is easy to manufacture and the accuracy of temperature control is improved.
The adhesive force with the molded connector insulation is weak and the mold can be easily removed. A hard chrome plating film is not chipped when assembling a die, and an electrically reliable connector insulator can be molded.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a mold suitable for molding a connecting portion insulator such as a crosslinked polyethylene insulated power cable.

[0002]

[Prior Art]

 A conventional method for connecting a cross-linked polyethylene insulated power cable will be described with reference to FIGS. 9 and 10. First, the protective sheaths 13A and 13B of the cross-linked polyethylene insulated power cables 11A and 11B to be connected, and the cross-linked polyethylene insulators 15A and 15B are stripped off (the inner conductive layer and the outer conductive layer are omitted), and the exposed conductors 17A and 17B are removed. Make a compression connection with copper sleeve 19.

Next, the mold forming the connecting portion insulator is covered with the halves of the molds 21A and 21B, and the outsides of the molds 21A and 21B are covered with casting heaters 23A and 23B to heat the molds 21A and 21B. In this state, polyethylene containing a cross-linking agent is injected into the molds 21A and 21B and heated and pressed. This causes a cross-linking reaction to form a cross-linked insulator for the connection part. After that, the mold is removed, the outer shape of the connection part insulator is shaped, and then the connection part protection member such as a plastic sleeve is covered to complete the connection. This connection method has already been put into practical use as a mold joint method for connecting cross-linked polyethylene insulated power cables up to 275KV.

[0004]

[Problems to be solved by the device]

 However, the conventional connection method, particularly the method for molding the connection portion insulator, has the following problems. In other words, since the conventional mold is made of steel and has poor thermal conductivity, it needs to be covered with a brass casting heater from the outside to heat it, resulting in an extremely large overall weight, and in a narrow manhole or tunnel. It is extremely difficult to handle inside.

Further, when a resin is injected into the mold to mold the connecting part insulator, the connecting part insulator and the mold are attached to each other, which makes it extremely difficult to remove the mold. Therefore, it is necessary to use a hydraulic jack or the like to remove the mold, which makes the work troublesome. An object of the present invention is to provide a mold for forming an insulator of a power cable connection, which solves the above problems.

[0006]

[Means for Solving the Problems]

 In order to reduce the weight of the mold, it is effective to make the mold lightweight and an aluminum alloy with good thermal conductivity, and to insert a rod-shaped heater inside. Also, in order to prevent adhesion between the molded insulation of the connecting part and the mold and facilitate mold removal, various research results have shown that the resin molding surface of the mold has fine holes or cracks. It has been found that it is effective to provide a metal plating film (hard chrome plating film, etc.) and bury the molding resin and non-adhesive resin (tetrafluoroethylene resin, etc.) in the holes or cracks. ..

However, when the length of the mold is more than 1 m, no matter how the mold is divided into the upper mold and the lower mold, not only a large processing machine is required for manufacturing, but also the heater arrangement is increased. The restrictions make temperature control difficult. In order to improve this, it is conceivable to divide the upper mold and the lower mold into a plurality of blocks in the longitudinal direction, and manufacture and assemble each block separately.

However, it has been found that the following problems occur when the upper die and the lower die are divided. That is, if the upper mold and the lower mold are divided and a metal plating film is formed on the resin molding surface of each block, when assembling the upper mold and the lower mold, the resin molding surface and the dividing surface are separated. This means that the metal plating film may be chipped at the corners, and there is a risk that metal powder will mix into the injected resin. If metal powder is mixed into the insulation of the power cable connection, the withstand voltage characteristics of the connection will be significantly reduced.If the upper and lower molds are of a split type, prevent the metal plating film from being chipped. Must.

The present invention has been made based on the above-mentioned examination results. That is, the mold for molding the power cable connection portion of the present proposal is composed of an upper mold and a lower mold, and the upper mold and the lower mold are each divided into a plurality of blocks in the longitudinal direction. A metal plating film is provided on the resin molding surface of the block, and this metal plating film has fine holes or cracks, and the molding resin and non-adhesive resin are embedded in the holes or cracks. Further, a chamfer is formed at the corner between the resin molding surface and the dividing surface of each block, and the chamfered portion is also formed with a continuous metal plating film from the resin molding surface. ..

[0010]

[Action]

 In the mold of the present invention, the upper mold and the lower mold are each divided into a plurality of pieces in the longitudinal direction, so that the mold is easy to manufacture, the degree of freedom in arranging the heater is high, and the temperature control is easy. In addition, a metal plating film having fine holes or cracks is provided on the resin molding surface of the upper mold and the lower mold, and the molding resin and the non-adhesive resin are embedded in the holes or cracks. Adhesion between the lower mold and the molded insulator of the connecting portion is weak, and the mold can be easily removed.

Further, the metal plating film has chamfered portions formed at the corners of the resin molding surface and the divided surface of each block, and is also formed at the chamfered portions, so that the metal plating film is formed at the corners. Since it is not square, there is no risk of chipping of the metal plating film when assembling the mold.

[0012]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 3 show an embodiment of the present invention. This power cable connecting part insulator forming mold is composed of an upper mold 31A and a lower mold 31B made of an aluminum alloy (for example, JIS A5052 alloy), and the upper mold 31A and the lower mold 31B are each a long It is divided into three blocks 31A1 to 31A3 and 31B1 to 31B3 in the direction. The three blocks are integrated by bolts 32 screwed from the blocks 31A1, 31A3, 31B1, 31B3 on both sides to the blocks 31A2, 31B2 in the central part.

Further, a required number of heater insertion holes 33 are formed in the axial direction in each of the blocks 31A1 to 31A3 and 31B1 to 31B3, and rod-shaped cartridge heaters 35 are inserted into the insertion holes 33. Aluminum alloy has about twice the thermal conductivity of steel, so there is no need to heat the entire circumference with a brass casting heater as in the past, and heating with the rod-shaped cartridge heater 35 provides a uniform temperature distribution. Be done. In particular, if the upper mold 31A and the lower mold 31B are divided into three, the central blocks 31A2, 31B2 and the blocks 31A1, 31A3, 31B1, 31B3 on both sides can be temperature-controlled separately, so that temperature control can be performed. It will be easier to do.

Further, a hard chromium plating film 39 having a thickness of 50 to 70 μm is formed on the resin molding surfaces of the upper mold 31A and the lower mold 31B. The hard chrome plating film 39 has innumerable minute holes or cracks 41 as shown in an enlarged view in FIG. This crack 41 can be formed by anodizing the hard chromium plating film 39 in a chromium electrolytic bath. Tetrafluoroethylene resin 43 is filled in the cracks 41 to keep the surface smooth. Fluorine resin such as tetrafluoroethylene resin has the property that it is difficult to adhere to the molded insulation at the connection part. That is, since the non-adhesive tetrafluoroethylene resin 43 is innumerably dispersed and exposed on the resin molding surface of this mold, the adhesive force with the molding resin is weakened as a whole of the resin molding surface.

By the way, when the hard chrome plating film 39 is formed on the resin molding surfaces of the upper mold 31A and the lower mold 31B, if the hard chrome plating film is formed in each of the divided blocks, as shown in FIG. The hard chrome plating film 39 is formed not only on the resin molding surface P but also on the dividing surface Q. For example, even if the adjacent blocks 31A1 and 31A2 are tightened with the bolts 32, a gap is formed between the dividing surfaces Q, The accuracy of the mold is reduced. In order to eliminate this, as shown in FIG. 7, if the adjacent blocks 31A1 and 31A2 are fastened with bolts (not shown), that is, the three blocks are joined together, the hard chrome plating film 39 is formed. Good.

However, even if plating is performed in a state where the three blocks are integrated, it is necessary to separate the blocks as shown in FIG. 8 due to insertion of a heater into each block after plating. At the time of this separation and the subsequent re-bonding, the hard chrome plating film 39 is likely to be chipped at the corner portion between the resin molding surface P and the dividing surface Q.

Therefore, in the present invention, as shown in FIGS. 1 and 4, a chamfered portion R is formed at a corner portion between the resin molding surface P and the dividing surface Q of each block 31A1 to 31A3, 31B1 to 31B3, and resin molding is performed. A hard chrome plated coating 39 is formed from the surface P to the chamfered portion R so as not to enter the divided surface Q.

In order to form such a hard chrome plating film 39, plating treatment is performed by arranging a plating electrode on the central axis of the resin molding surface in a state where the three blocks having the chamfered portion R are connected. Good. Then, as the chamfered portion R becomes closer to the dividing surface Q, the distance from the plating electrode becomes larger. Therefore, the hard chrome plated coating 39 whose thickness becomes smaller as it approaches the dividing surface Q can be formed on the chamfered portion R. The hard chrome plating film 39 formed in this way does not vary at the corners between the resin molding surface P and the dividing surface Q, so even if the three blocks are separated or recombined after plating. , There is no risk of chipping of the plating film. The radius of curvature of the chamfered portion R is about 2 mm.

The upper mold 31A and the lower mold 31B are tightened by bolts 44 and nuts 45 as shown in FIG. An elongated stainless steel plate 47 straddling a plurality of bolt nuts is interposed between the bolt nuts 44, 45 and the molds 31A, 31B. As a result, even if the upper mold 31A and the lower mold 31B are repeatedly opened and closed, the molds can be uniformly tightened.

The mold of the present embodiment configured as described above has a size of an inner diameter of 160 mm and a length of 1000 mm, and the outer dimensions are the same as those of the conventional mold, but the overall weight is the same as that of the conventional mold. Weighing about 200 kg, we were able to reduce it to about 70%, about 1/3 of that amount. In the above mold size, a hydraulic jack was required to open the mold after molding the connection insulator, but the mold of this example has a mold weight of about 10 to 20 kgf. It was possible to open it manually by applying the force of.

Further, four 200 W rod-shaped cartridge heaters 35 are inserted into each of the blocks 31A1 to 31A3 and 31B1 to 31B3, and thermocouples are provided to control the temperature of each block individually. As a result, it was confirmed that the mold temperature could be suppressed to within ± 10 ° C of the set temperature of 100 ° C. If the upper die and lower die are not split type, there is no choice but to insert a long heater of 50 cm or more into a straight hole opened in the longitudinal direction, so there is a temperature difference of 30 to 40 ° C between the center and both ends. It was a significant improvement compared to this.

[0022]

[Effect of the device]

 As described above, according to the present invention, since the upper mold and the lower mold are each divided into a plurality of blocks in the longitudinal direction, the processing size is small and the manufacturing is easy, and at the same time, each block is Since a heater can be placed in the temperature control system, the accuracy of temperature control can be improved. In addition, the upper mold and the lower mold have a structure in which a metal plating film is provided on the resin molding surface and the molding resin and non-adhesive resin are embedded in the holes or cracks formed in the resin molding surface. Since the adhesive force to the body is weak, the mold can be easily removed.

Further, a chamfer is formed at the corner between the resin molding surface and the division surface of each block, and the metal plating film continuous from the resin molding surface is provided on the chamfered portion. There is no risk of the metal plating film being chipped during assembly, etc., and it is possible to mold a highly reliable electrically insulating connector.

[Brief description of drawings]

1 is a vertical cross-sectional view of a mold for molding an insulator of a power cable according to an embodiment of the present invention.

2 is a cross-sectional view taken along the line AA of the mold of FIG.

FIG. 3 is an enlarged cross-sectional view taken along the line BB of FIG.

FIG. 4 is an enlarged cross-sectional view in the vicinity of a split surface of the mold shown in FIG.

FIG. 5 is an enlarged cross-sectional view showing a state where the split surface of the mold of FIG. 1 is opened.

FIG. 6 is a sectional view showing a problem when the mold is divided in the longitudinal direction.

FIG. 7 is a cross-sectional view showing a state in which a metal plating film is formed in a state where adjacent blocks are joined together.

8 is a cross-sectional view showing a state where adjacent blocks in FIG. 7 are separated.

FIG. 9 is a vertical cross-sectional view showing a usage state of a conventional power cable connecting portion insulator molding die.

10 is a cross-sectional view taken along the line C-C of the mold shown in FIG.

[Explanation of symbols]

31A: Upper mold 31A1 to 31A3: Block 31B: Lower mold 31B1 to 31B3: Block 35: Rod-shaped cartridge heater 39: Hard chrome plating film 41: Fine crack 4
3: Tetrafluoroethylene resin P: Resin molding surface Q: Dividing surface R: Chamfer

Claims (1)

[Scope of utility model registration request] 1. An upper mold and a lower mold, wherein the upper mold and the lower mold are each divided into a plurality of blocks in the longitudinal direction, and a metal plating film is provided on a resin molding surface of each block. This metal plating film has fine holes or cracks, and the molding resin and non-adhesive resin are embedded in the holes or cracks, and the corners between the resin molding surface and the dividing surface of each block. A mold for forming an insulator for a power cable connecting portion, wherein a chamfered portion is formed in the portion, and the chamfered portion is also formed with a metal plating film continuous from the resin molding surface.