EP1147525A1

EP1147525A1 - Method and device for producing composite insulators

Info

Publication number: EP1147525A1
Application number: EP99968343A
Authority: EP
Inventors: Heinz Denndörfer
Original assignee: Ceramtec GmbH
Current assignee: LIW Composite GmbH
Priority date: 1998-12-17
Filing date: 1999-12-08
Publication date: 2001-10-24
Anticipated expiration: 2019-12-08
Also published as: EP1147525B1; WO2000036615A1; ATE294446T1; ES2242445T3; DE59911995D1; DE19858215A1; DE19858215C2

Abstract

Composite insulators can fulfill their task in a manner which is free of interferences only when the protective sheathings do not comprise seams, gaps and ridges. When the casing and the sheath are simultaneously molded in a work process, ridges can result on the surface of the composite insulator due to mold seams and thereby form sources of interference. Moreover, only composite insulators having a predetermined number of annular sheathes can be produced using these molds. The aim of the invention is to produce composite insulators having any number of annular sheaths and having a sheathing without seams, welds or gaps. To this end, the advance of a core (102) is stopped when applying a material (36) of the sheathings (3) to a rod-shaped or tubular core (102) which is transported in the longitudinal direction thereof and which is comprised of a composite material. In addition, an annular sheath (5) is molded using a mold (15), said mold, when viewed in a direction of transport (31), advances the core (102) in front of the system (12) for applying the material (36) of the sheathing (3). The invention also provides that the advance of the core (102) is resumed after the sheathing (5) has been molded, and the application of the material (36) is continued. The material (36) of the sheathing (3) is applied to the core (102) in an uninterrupted manner until the sheathing (3) has been completely produced.

Description

Method and device for producing composite insulators

The invention relates to a method for producing composite insulators according to the preamble of the first claim and to a device for producing composite insulators according to the preamble of the nineteenth claim.

In addition to the conventional materials porcelain and glass, high-voltage insulators are increasingly being manufactured as composite insulators. Composite insulators consist of a rod-shaped or tubular core, which in turn is composed, for example, of epoxy resin reinforced with glass fibers and a shield cover, divided into a jacket around the core with a number of spaced, plate-shaped shields or one or more spiral shields, the shield cover consisting of one Material with insulation properties exists. These materials include elastomeric materials, for example polymeric plastics. The core can be easily encased with such materials before the material finally obtains its desired mechanical and electrical properties by means of a subsequent thermal treatment.

The core of a composite insulator is used to absorb the forces that act on the insulator due to the suspension and therefore carries appropriately designed fittings, usually made of metal, at its ends. The shield cover is intended to prevent electrical flashovers, usually due to weather conditions. Composite insulators have the advantage over conventional insulators made of glass or porcelain that they are considerably lighter. In addition, they have very good insulation properties due to the dirt and water-repellent material of the shield covers and are therefore particularly suitable for areas with a heavily polluted atmosphere. However, this property is only achieved if the coating of the core is not interrupted at any point or lifted off the core, for example by joints, seams or gaps. DE 196 29 796 A1 discloses composite insulators and methods for their production. The sheath and the screen are continuously formed in one step. According to the known methods, however, only composite insulators with spiral shields can be produced. Experience with such composite insulators is currently still considered to be too little.

The object of the present invention is to present a method and a device with which the production of composite insulators with any number of ring-shaped shields and a continuous shield shell is possible.

This object is achieved by the method according to the invention with the aid of the characterizing features of the first claim. A device according to the invention for producing the composite insulators is characterized by the features of claim nineteen.

Compared to the known methods for sheathing the cores of composite insulators, it is possible with the method according to the invention to produce composite insulators in succession with any number of ring-shaped shields and in any length, the shield shell being continuous and having no joints, seams or gaps. For this purpose, the core, as is known from DE 196 29 796 A1, is guided centrally at a constant speed through the mouthpiece of a device for applying the material of the screens, for example an extruder or a piston press, the material being applied to the core on all sides . In contrast to the known method, the annular screens are shaped in such a way that, seen in the direction of advance of the core, a shape is delivered to the device before the device for applying the material. While the core is stopped, the mold is filled with the material of the shield cover and a shield is formed. When the screen has reached the intended shape, the shape is opened, the screen is released and the feed of the core is started again. The supply of the material is controlled so that the application of the material is not interrupted until the Umbrella cover is completely made. As a result, the shield cover has no joints, seams or gaps at any point on the composite insulator.

From DE 42 02 653 A1 it is known to form the complete shielding cover with annular shields in a shape around the core. Since the shape is divisible in the plane in which the core lies, the shield cover has two opposite ridges along its entire length. Burrs must be removed as much as possible because they are sources of interference with the insulation, especially if they are on the top and on the circumference of the shields. Burrs are collection points for dirt, which can significantly reduce the insulation properties. In a further development of the invention, burrs can be avoided, in particular on the circumference of the screens, in that the shape with which the screens are shaped is greater in its radial extent than the radius of the screen and is not completely filled with the material of the screen cover. so that the parting line is not reached by the material. The mold half for shaping the top of the screens should be in one piece to avoid burrs. Due to the advantageous design of the shape, a work step for removing the burrs is eliminated.

When opening the mold, the surface of the screens can stick to the mold walls. This makes the screens difficult to shape and there is a risk that their surface will be damaged. The tendency to stick can be material-related, but can also be caused by the adhesion of the screen surface to the shaping surfaces of the mold, the mold walls, if the supply of air to the places where the screen surface is to be detached from the mold walls is difficult. In order to facilitate the shaping of the screens, it is advantageous to use a material with a high Williams plasticity. The tendency to adhere to surfaces decreases with increasing Williams plasticity. A non-stick additive can also be added to the material to reduce its tendency to stick. The risk of the material of the screen cover sticking to the mold walls can further be reduced by the mold walls being made of a material which has so-called non-stick properties, such as polytetrafluoroethylene.

In the case of materials that tend to stick, in particular, for example, silicones, the following process steps are advantageous when molding the screens: The filling of the mold is monitored with at least one pressure sensor on or in the mold. At a certain pressure corresponding to the degree of the desired filling, the mold is opened a predetermined gap. For this purpose, the mold half lying forward in the feed direction of the core is first displaced in the feed direction of the core, for example by about one millimeter, in order to reduce the pressure on the material and to release its adhesion to the mold walls. Only then will the mold be fully opened to release the screen.

However, the adhesion to the shaping surfaces of the mold can be so great that it must be overcome by further process steps. In order to ensure damage-free shaping of the shields, the detachment of the shield surface can be supported by supplying air to the shield surface, in particular at particularly vulnerable points on the shield, such as the shield root. For this purpose, channels are provided in the mold walls, which end on the shaping surfaces. The channels are closed to the shaping surfaces by valves which open when a vacuum is created when the screen surfaces are detached from the molding walls. The detachment can be supported with compressed air which is blown in through the valves.

The detachment of the screen surfaces from the mold walls can also be supported mechanically by rotating at least one mold half with respect to the other around the longitudinal axis of the core, material which may be adhering to the mold walls being detached due to the shearing movement. The mold half lying in front in the direction of transport must be formed at least in two parts in order to be able to clear the path for the screen by opening in a substantially radial direction, by pulling apart or opening. Both mold halves can also be formed in two parts. When the mold is opened, the partial halves of the one mold half can be opened with a time delay relative to the partial halves of the other mold half, the partial halves in turn being moved away from the core in a substantially radial direction. This procedure avoids deformation of the screen in the opening direction, which could occur when the partial halves are opened at the same time.

Another way of overcoming the tendency of the shielding material to stick to the mold walls is to heat the mold. The heat treatment can be limited to the hardening of the surface, so that the screen can be easily molded. The final heat treatment would then take place in a further process step. The heat treatment can also include the entire process required for curing the material of the shield cover.

The fittings are attached to the ends of a core, with which the insulator itself is attached on one side and the electrical conductor on the other side. To attach the fittings to the core, the ends of the core must be free from the material of the shield cover. In the manufacture of a composite insulator according to the invention, when the beginning of the core emerges from the device for applying the material of the shielding sleeve, the application of the material is suspended until the length provided for fastening the armature has left the device. When the point at which the armature should support the armature is reached at the end of the core, the supply of the material is interrupted. The jacket then tears off as the core advances on the device for applying the material and the core remains bare. Another way of obtaining a sheath-free end of the core is to push the rod jerkily around the piece that is to remain free while the sheath material is continuously conveyed. Due to its viscosity, the sheath material tears off during advancement and is only reapplied when the core is transported through the device for applying the shield cover at the usual advancing speed.

The process steps described above save one work step for the subsequent removal of the jacket at the ends of the core, where it should carry the fittings. It also saves material that would otherwise be lost.

A simplification of the workflow for the production of a composite insulator is achieved if not every core has to be fed individually to the device for applying the material of the shielding cover. If the rod or tube made of glass fiber reinforced plastic intended for the cores is so long that at least two composite insulators can be produced in succession, a fully molded composite insulator or at least the already fully molded part of the composite insulator can be passed through a heating device without any support on the not yet hardened material of the shield cover is required. Subsequently, the composite insulator or at least the part of the composite insulator that has already been subjected to the heat treatment can support the part still to be subjected to the heat treatment, which has already left the device for applying the material of the shielding cover.

Instead of producing individual composite insulators, the production process can also be carried out continuously if a subsequent core is connected to the preceding core to form a continuous rod or tube of great length. With a corresponding quality of the connection of the rods or tubes to one another, there is the possibility of producing composite insulators of different lengths in succession. So the length of the composite insulators will not more determined by the length of the individually fed cores, but by the specified number of screens. The cores are then separated when the specified number of shields and thus the specified length of a composite insulator is reached. The connection can be made, for example, by gluing the rods or tubes to one another or by thermal bonding. However, if the connection of the rods or tubes is only used to create a continuous rod or tube of great length and the connection points do not meet the mechanical requirements for the core of a composite insulator, such a connection point can be defined as a point for separating finished composite insulators become.

In the manufacture of the composite insulators, the procedure can advantageously be such that the parts of the composite insulator that have already been molded after the application of the material of the shielding sleeve are thermally treated to produce the required material properties of the finished shielding sleeve, while the material for molding the remaining part of the composite insulator or already for forming the subsequent composite insulator is applied to the continuous core if, due to the supply of long rods or tubes for the individual separation of cores, continuous production of composite insulators is provided. In contrast to the prior art, these process variants no longer have to wait for the complete completion of a composite insulator before the required thermal treatment can take place.

During the thermal treatment of composite insulators with heat radiation sources that act on the composite insulators from the outer circumference, there is a risk of the thin shield edges overheating. Uniform heating of the jacket and in particular the screens is advantageously achieved in that hot air is used for heating. The heating section through which the composite insulator travels is equipped with a hot air blower that ensures an even Temperature distribution and thus ensures uniform heating of the shield cover.

If the material of the shield cover has a correspondingly high dipole moment, for example silicone rubber (HTV) or ethylene-propylene copolymer (EPM), vulcanization with high-energy radiation, for example with a microwave, is also possible.

The handling of the composite insulators during their manufacture is facilitated in particular by the fact that at least one composite insulator that is already finished and that is still connected via the core to the subsequent, not yet finished composite insulator is supported by a conveyor. The conveyor is downstream of the heating device. The continuous rod or tube from which the finished composite insulators are cut off is supported on one side in the drive rollers of the feed device for the rod or tube and is supported on the other side by a finished composite insulator. This makes it possible to transport a composite insulator that has not yet been manufactured without the support of its still soft shielding shell during its shaping and subsequent thermal treatment. This prevents deformation or damage to the shield cover. The conveyor can be, for example, a non-driven conveyor belt on which the already finished composite insulators rest with the outer circumference of their screens. The composite insulators are moved solely by the feed of the core. The feed takes place by means of a feed device through the device for applying the material of the shield cover. The conveyor belt moves forward solely through the composite insulators resting on it. The conveyor can also be driven. They must be driven synchronously with the drive of the rod or tube.

The method according to the invention for producing composite insulators is explained below on a device provided for this purpose. Show it:

FIG. 1 shows the structure of a composite insulator,

Figure 2 shows a device for producing inventive

Composite insulators,

Figure 3 shows in detail a device for forming a continuous rod from which the cores of the composite insulators are cut off, and

Figure 4 as a detail further embodiments of a shape for shaping a screen.

FIG. 1 shows the structure of a composite insulator according to the invention as it leaves the device according to the invention for producing composite insulators before it is separated from the core of the subsequent composite insulator.

The composite insulator 1 consists of a core 2, which is covered with a shield cover 3. The screen cover 3 is divided into a jacket 4 and ring-shaped screens 5. For the sake of clarity, only one screen 5 is shown here. A composite insulator has five sections. Section A represents the first end 6. It has no jacket 4. This free end 6 has a dimension 8, which is required for fastening a valve, not shown here. In section B, the core 2 is covered with a jacket 4. In section C there is the annular screen 5 and in section D the core 2 is also covered with a jacket 4. The area E comprises the second end 7 of the insulator 1 and has the dimension 9 which is required for fastening the further fitting, not shown here. A region A of the subsequent insulator 101 is in turn connected to the region E, which region is not shown here completely and is also not yet to be completed. As can also be seen from FIG. 1, the core 2 and the core 102 of the subsequent composite insulator 101 form a continuous rod 14 in the present exemplary embodiment. The core can also be formed from pipes. At the point 10, the composite insulator 1 which has already been completed is separated from the composite insulator 101. As can also be seen from FIG. 1, the jacket-free end 7 of the core 2 of the composite insulator 1, the separation point 10, is followed by the first end 106 of the core 102 of the composite insulator 101, on which a fitting is also to be attached. This end 106 is therefore also free of the sheath 4 in a length 108.

FIG. 2 schematically shows an exemplary embodiment of a device 11 according to the invention for producing composite insulators. Only the features contributing to the invention are shown and described.

In the present exemplary embodiment, the device 11 for producing composite insulators essentially comprises a device 12 for applying the material of the shielding sleeves 3, to which a long rod 14 made of glass fiber-reinforced plastic is fed via a feed device 13, from which the cores 2, 102 of the composite insulators 1, 101 are formed. Furthermore, the device 11 includes a shape 15 for shaping the screens 5, which is arranged in front of the device 12 for applying the material of the screen covers 3. In the present exemplary embodiment, the device 12 is followed by a heating section 16 for the thermal treatment of the material of the shield cover, a transport device 17 and a separating device 18 for separating the finished composite insulators 1 from the rod 14. The rod 14 is produced by assembling it from shorter sections 19. While the cores 2 of the finished composite insulators 1 are separated from the rod 14, 3 new sections 19 are added before it enters the device 12 for applying the material of the shield sheaths, so that a continuous production of composite insulators is possible. The type of connection between two sections, rods or pipes depends on the intended process. If only composite insulators are to be produced that are just as long as the rods or tubes connected to each other, each rod or tube forms a core. These cores only need to be connected to one another to the extent that they can be transported together. For this purpose, it is already sufficient, for example, to connect two rods or tubes which abut one another on the end faces by means of adhesive tape.

However, if the sections are to be permanently and resiliently connected, other connection methods are required, for example gluing, thermal connection, friction welding or by means of pins.

Only one example of the possible connection methods is described here. The sections 19 are permanently connected to the end of the rod 14 by gluing in an adhesive device 21, which is shown in FIG. 3. It is connected upstream of the device 12 for applying the material of the shielding sleeves 3. The adhesive device 21 can, for example, be slidably suspended on a hanging rail 23 by means of rollers 22 in order to be able to participate in the advancing movement of the rod 14 during the adhesive process. The adhesive device 21 holds the rod 14 in place during the pushing operation with a firmly arranged gripper 24. A gripper 25, which can be pushed back and forth in the direction of the longitudinal axis 26 of the rod 14, as is indicated by the double arrow 27, holds a section 19 to supplement the bar 14. The section 19 is fed via support rollers 28, the spacing of which from one another the diameter of the sections is adjustable. For example, a nozzle 29 is used to apply adhesive to the end face 20 of the rod 14. Then the section 19 is pressed by means of the gripper 25 in the direction of arrow 30 with its end face 20 against the end face 20 of the rod 14 wetted with adhesive and held until the adhesive connection is resilient. During this time, the adhesive device 21 moves in the feed direction 31 of the rod 14, which is possible by running on the hanging rail 23. After the end of the pushing process, the grippers 24 and 25 are opened and the adhesive device 12 on moved the free end of the just glued section 19 to glue the next section there.

The production of composite insulators using the device according to the invention shown in FIG. 2 is described below.

5 The manufacture of composite insulators can be carried out fully automatically, the process sequences in the individual devices being coordinated with one another by means of a control device 32. The individual devices are connected to the control device 32 via signal and control lines 33.

At the start of the device 11 for the production of composite insulators 1 is a rod

10 14 in the feed direction 31 through the open drive rollers 34 of the

Feed device 13 in the spray head 35 of the device 12 for applying the

Introduced material of the shield cover. The device 12 is in the present

Embodiment an extruder. The material 36 from which the shielding sleeves 3 are formed is an HTV silicone rubber in the present exemplary embodiment. Is It is a tape from a supply roll in a known manner by a rotating

Screw 37 is drawn into the extruder 39 and pressed out through a nozzle surrounding the rod 14 in the spray head 35 and applied to the rod 14 in a uniformly thick layer. So that the application of material 36 for the shield cover

3 takes place evenly, the drive 40 of the screw 37 is via a synchronous controller

20 41 connected to the feed device 13 of the rod 14.

In order for the shielding cover 3 to adhere well to the core 102 of the composite insulator 101 still to be produced, an adhesive is applied in a device 42 which is connected upstream of the feed device 13 in the present exemplary embodiment and through which the rod 14 passes. Furthermore, a length measuring device 43 25 is provided which rests on the surface of the rod 14 with a feeler wheel 44. With the length measuring device 43, the feed of the rod 14 is monitored, the length of the Cores 2 and 102 and the distances between the screens are measured from one another and the separating device 18 and the application of the material of the screen sheaths 3 are controlled.

The rod 14 is inserted so far into the spray head 35 that its end face corresponds to the outlet opening of the ring nozzle, not shown here. Then the feed device 13 is switched on, the extruder 12, the device for applying the material 36 of the shielding sleeves 3, but not yet. Only when the rod 14, which is now the future core of a new composite insulator, by the length 8, section A in FIG. 1, given by the fastening of the fitting, has the extruder 12 been switched on and the material 36 applied to form an umbrella cover 3. The first jacket 4 is formed. After the length specified by the control device 32 has been determined by the length measuring device 43, the advance of the rod 14 is stopped. Section B of the composite insulator is thus produced. For a time specified by the control device 32, the screw 37 continues to convey the material 36 to form the shielding cover 3 in the area C. As a result, the extrudate 45 swells concentrically around the rod 14 from the application nozzle and formed a screen 5 therefrom.

A mold 15 is used to shape a screen 5. It consists of two halves 46 and 47, the first half 46 being arranged directly on the end face of the spray head 35, on which the rod 14 emerges. The second mold half 47, as seen in the transport direction 31 of the rod 14, is arranged behind the first mold half 46. The two mold halves 46 and 47 are divided in a plane 48 which is substantially perpendicular to the longitudinal axis 26 of the rod 14, as indicated by the right angle 49. While the first mold half 46 is firmly connected to the spray head 35, the second mold half 47 can be moved along the longitudinal axis 26 of the rod 14 in the direction of the first mold half 46 in order to open and open it, as indicated by the double arrow 50 . In order to clear the way for the freshly formed umbrellas, the second mold half 47 is divided at least once more into two part halves 51 and 52, the parting plane 53 being perpendicular to the first parting plane 48 and going through the longitudinal axis 26 of the rod 14. The division of the mold half 47 makes it possible to move its partial halves 51 and 52 essentially radially to the longitudinal axis 26 of the rod 14, that is to say essentially in the division plane 48, as indicated by the double arrow 54. The two partial halves 51 and 52 of the mold half 47 can be opened and closed by means of a device 55, as is also indicated by the double arrow 54. It is also possible, but not shown here, to open the two halves like two gate leaves. In addition, the device 55 also takes over the opening and closing of the two mold halves 46 and 47 for shaping the screens. The device 55 is connected to the control device 32 via a control line 33.

To form a screen 5, the partial halves 51 and 52 of the mold half 47 are brought together and then the mold half 47 is moved towards the mold half 46. The extrudate 45 provided for the formation of a screen is enclosed by the mold 15 and a screen 5 is formed. Since the amount of extrudate 45 is such that it does not fill the mold 15 to the parting line, there is no burr on the circumference of a screen 5 at the point where the two mold halves 46 and 47 meet.

The shaping of a screen 5 can also take place in such a way that the mold 15 is already closed when the feed of the rod 14 is stopped. The extrudate 45 intended for shaping a screen is then conveyed into the closed form. Here too, the delivery rate of the extrudate can be predetermined by the control device 32 over time. It is also possible to control the filling quantity via pressure sensors in the mold 15 or on the walls of the mold halves 46 and 47, as is not shown here. Since the mold half 47 is again divided into two partial halves 51 and 52, a burr can arise at the parting line. In order to avoid this to the greatest possible extent, the formation of a sharp and thus disruptive burr can be avoided by appropriate shaping of the edges of the partial halves, for example by rounding. In addition, the mold half 47 can be provided for shaping the underside of the screens, so that the top of the screens can be molded completely free of burrs with the one-piece mold half 46.

After shaping a screen 5, the mold 15 must release the screen without damaging its surface. In the case of materials which tend to adhere to the shaping surfaces of the mold 15, for example in particular silicone rubber, the mold halves 46 and 47 must be opened carefully so that the screen surface is not damaged. The procedure can be such that the filling of the mold 15 is monitored by means of pressure sensors, not shown here. At a certain pressure corresponding to the degree of the desired filling, the mold is opened a predetermined gap. For this purpose, the mold half 47 is first pulled back slowly and in the direction of the longitudinal axis 26 of the rod 14, for example by approximately one millimeter, in order to reduce the pressure on the material and to loosen its adhesion to the mold walls. Only then is the mold fully opened to release the screen and the two partial halves 51 and 52 pulled apart radially to the longitudinal axis 26 in the direction of arrow 54. When the feed device 13 is switched on and the rod 14 is fed, the screen 5 is then lifted off the mold half 46.

In order to reduce the tendency of the shielding material to stick to the walls of the mold halves, these can also be coated with a material which reduces the tendency to stick, for example polytetrafluoroethylene. The detachment of the surface of the screen from the mold walls can also be supported mechanically by turning the two mold halves against one another when the mold is still closed. When the shaping of the screen 5 is complete, the area C of a composite insulator 1 is produced according to FIG. When the feed device 13 for feeding the rod 14 is switched on, the extruder 12 is switched on at the same time, so that the coating of the jacket connects to the screen 5 without interruption. The length of the jacket 4 to be applied until the formation of a further screen is determined by the control device 32. After the predetermined length of the jacket 4 has been determined by the length measuring device 43, the feed device 13 is stopped and in the case of composite insulators with a plurality of screens, another screen is shaped.

As the composite insulator grows, its first end moves further and further away from the spray head 35 and plunges into the heating section 16 which is arranged downstream of the extruder 12. A thermal treatment of the still soft material of the shielding cover 3 takes place in the heating section 16 so that it achieves the mechanical and electrical properties required for an insulator.

The heating section 16 is a continuous furnace in the present exemplary embodiment. The raw shield shells are heat-treated with hot air in accordance with the method according to the invention. This ensures uniform heating of the shield covers, which prevents local overheating.

The hot air is generated by means of a blower 56 with a downstream heater 57 and is evenly blown into the continuous furnace 16. The temperature and the air throughput are regulated via the control device 32. The length of the continuous furnace 16 and the thermal treatment of the shield cover are matched to the material of the shield and the feed speed of the rod 14.

Seen in the feed direction 31, the already finished areas of the composite insulator 101 leave the continuous furnace 16. The screens 5 are now fixed, so that they no longer deform when they are used to support the composite insulator. The screens 5 of the composite insulator 101 leaving the continuous furnace 16 are pushed onto a transport device 17, in the present case Embodiment an undriven, endless conveyor belt 58, which is wrapped around deflection rollers 59, of which only one can be seen here. The conveyor belt 58 is moved exclusively by the advance of the composite insulators 1 lying on the conveyor belt. The conveyor belt is so long that there is still space for at least one further, fully finished composite insulator 1. Because all the cores 2 and 102 of the composite insulators 1 and 101 form a continuous rod 14, it is possible to transport the nascent composite insulator 101 with its still soft shield cover 3 through the continuous furnace 16 without support.

If the core of a composite insulator is completely covered with a shield cover in the areas provided for this purpose, the application of the material 36 of the shield cover 3 is stopped via the control device 32, while the feed of the rod 14 continues. By stopping the extruder 12, the shield cover 3 tears off when the rod 14 is advanced and the rod 14 remains bare. The application of the material of the shield cover remains interrupted until the length measuring device 43 has determined that the rod 14 has been advanced by a distance which corresponds to the length required for fastening the fittings on the cover which has just been coated with the shield cover and the subsequent composite insulator to be manufactured is required. In addition, the thickness of the saw blade of the cutting device 18 is taken into account. Then the application of the material for the shield cover of the subsequent composite insulator is resumed.

As can be seen from FIG. 2, two finished composite insulators 1 have already run onto the transport device 17. On the transport device 17, the separating device 18 is arranged at such a distance from its beginning, the deflection roller 59, that, in addition to two completely finished composite insulators 1, at least one already fully hardened shield 5 of a composite insulator 101 still to be finished rests on the conveyor belt 58. This provides good support for the composite insulator 101 that is still to be completed reached. The separating device 18 can be moved into corresponding positions with respect to the length of the composite insulators to be produced, such as with the double arrow

60 is indicated. For this purpose, the separating device 18 can, for example, have rollers

61 slidably suspended on a hanging rail 62. To separate a finished composite insulator 1, the separating device 18 is replaced by a

Positioning instruction directed by the length measuring device 43 from the control device 32 to a point on the transport device 17 where the separation point 10 lies on the conveyor belt 58 between two composite insulators 1, delivered for separation at the separation point 10 and moved back after the separation process, as indicated by the double arrow 63 is indicated. The finished composite insulators are always separated when a screen is being formed and the feed device 13 of the rod 14 is stationary. The separating device 18 fixes the end 7 of the composite insulator to be separated during the separation process with a gripper 64 which can be fed to the composite insulator 1. The core 2 of the insulator 1 is cut off from the rod 14 which is still continuous with a saw 65. After the separation process, the gripper 64 is opened and pulled back and the separation device 18 returns to its starting position. The separated composite insulator 1 can now be removed for further processing or is transported to a collecting point (not shown here) when the transport device 17 is restarted.

If the adhesive connections in the rod 14 do not meet the requirements for the strength of the rod, the formation of the rod 14 can be chosen so that each glued rod is only as long as the core of a composite insulator. Thus, each glue point would then again be a separation point 10 and no core would contain a glue point.

FIG. 4 shows two ways of designing a shape. Only half of a section through the shape and the screen is shown. For a complete display, a reflection on the longitudinal axis 26 of the rod 14 would be required. The mold 15a is closed and consists of the mold half 46a, which is arranged in front of the spray head, not shown here, and the mold half 47a. The two mold halves 46a and 47a are divided in the parting plane 48, which is perpendicular to the longitudinal axis 26 of the rod 14, as indicated by the right angle 49. The division plane 48 also forms the underside 66 of the screen 5. The top 67 of the screen 5 lies in the mold half 46a. The shaping of the screen 5 has already been completed. In front of the screen 5, the jacket 4 of the screen cover 3 extends on the rod 14.

A burr that could be caused by the parting line 68 of the two mold halves 46a and 47a is prevented by the following measures:

Dosage of the extrudate to form a screen is done so that the

Shaping of a screen 5 provided mold space 69 of the shape 15a not up to

Parting line 68 is filled. The radial extent R of the mold space 69 is greater than the radius r of the screen 5 actually reached. The parting line 68 is not closed in the edge region 70 of the screen 5. The parting line 68 between the two mold halves 46a and 47a can either over the entire circumference of the mold

15a be open so that the two mold halves are spaced from one another, or the two mold halves abut one another, but have radially directed, on the

Circumferentially distributed grooves that form channels when the mold is closed to allow the air to escape from the mold space 69 when the screen 5 is molded.

The shaping surface 72 of the mold half 47a, which forms the underside 66 of the screen 5, is smooth in the present exemplary embodiment. However, it can also be concentrically corrugated or ribbed. This creates umbrellas with a larger creepage distance. In the case of screens designed in this way, fewer screens are required per insulator than smooth screens.

The central opening 73 in the mold half 47a, which surrounds the core 102 covered with the jacket 4, has a larger diameter 74 than the diameter 75 of the core 102 with jacket 4. The difference should be about 0.5 mm be. The gap 76 caused in this way prevents the jacket 4 from being damaged when the mold half 47a is closed and opened.

When the shaping of a screen 5 is completed, problems can arise when opening the mold in that the bottom 66 and the top 67 of the screen 5 adhere to the shaping surfaces 73 and 71 of the mold halves 46a and 47a by adhesion due to the negative pressure that occurs. This effect can occur even with the materials of the shield cover that do not tend to stick. In order to facilitate the detachment of the screen surface from the mold halves, it is advantageous if, when the two mold halves 46a and 47a are opened, the air can flow in between the shaping surfaces and the screen surface. The inflow of air favors the release of the screen surface from the mold walls. A negative pressure between the screen surface and the mold walls that occurs when the mold halves are opened is reduced and the suction effect is overcome. Poppet valves 77 can be provided in the mold halves for the inflow of air. They should preferably be arranged in the areas of the mold in which the risk of the screen surface sticking due to the difficult air access is greatest, such as in the area of the screen root. In the present exemplary embodiment, a poppet valve is arranged in the mold half 46a in the region of the shield root 78.

The plate 79 of the valve 77 is flush with the shaping surface 71 of the mold half 46a. The valve disk 79 is pulled into the valve seat 82 by a spring 81 acting on the valve stem 80. In the present exemplary embodiment, the valve 77 opens only when the negative pressure builds up in the mold space 69 or when compressed air is supplied from the outside via an adjustable nozzle 83, as indicated by the arrow 84. The force of the springs 81 is set in such a way that when a certain negative pressure is reached which occurs when the mold is opened, the plate 79 of the valve 77 lifts off the valve seat 82. The negative pressure is predetermined so that deformation of the screen 5 is avoided. In addition to inflowing the air presses the plate 79 on the screen surface and lifts it from the shaping surface 71.

The detachment of the screen 5 from the mold walls can additionally be supported by the supply of compressed air 84 by means of the nozzle 83. For this purpose, the nozzle 83 is placed with its conical mouthpiece 85 in the funnel-shaped adapter 86, which is connected to the poppet valve 77 via a channel 87 and opens above the valve plate 79. If the compressed air supply 84 is initiated, the valve plate 79 is lifted against the force of the spring 81 from the valve seat 82 and releases the supply of air into the mold space 69. A brief supply of compressed air can also take place shortly before the mold is opened. As a result, the screen surface detaches from the mold walls at the critical points before the two mold halves are opened.

Another possible embodiment of a mold 15b is shown below the longitudinal axis 26 of the rod 14. Features matching shape 15a are identified by the same reference numerals. In the present exemplary embodiment, the two mold halves 46b and 47b are equipped with a heater for the thermal treatment of the material of the shield cover. In the mold halves 46b and 47b, heating wires 88 are let in at certain intervals from one another and are connected via connections 89 to a controllable current source, not shown here. By specifying the current strength and the time, a predefined temperature and thus a predefined state of the material of the shielding cover can be achieved. Either a completed thermal treatment can take place until the screen has completely hardened, or the material is pretreated to such an extent that the surfaces 66 and 67 of the screen 5 already become so hard that they can be easily removed from the mold. The final thermal treatment would then take place in a continuous furnace.

The last-described embodiment of a mold can additionally, as is not shown and described here, be combined with the previously described embodiment with the valves for supplying air.

Claims

claims

1. A method for producing composite insulators, a rod-shaped or tubular core of composite material, which is conveyed in its longitudinal direction, being coated with a shielding sheath made of a material with insulating properties in a device for applying the material, at least one shield being formed from this material,

characterized,

that the shaping of the screen of the feed of the core is stopped, that with the help of a shape that the core seen in the transport direction before

Device for applying the material of the shield cover is delivered, an annular screen is formed, that after the shield has been removed, the feed of the core is resumed and the application of the material is continued and that the application of the material of the shield cover on the core is not interrupted until that the shield cover is completely made.

2. The method according to claim 1, characterized in that the shape substantially divided in a plane perpendicular to the longitudinal axis of the core for shaping the screens to avoid the formation of burrs is not completely filled up to the parting line with the material of the screen cover.

3. The method according to claim 1 or 2, characterized in that a material with a high Williams plasticity is used to reduce the tendency to stick of the material of the shield cover on the mold walls.

4. The method according to claim 1 or 2, characterized in that a non-stick additive is added to reduce the tendency to stick to the material of the shield cover.

5. The method according to any one of claims 1 to 4, characterized in that the fill level of the material of the shield cover in the form based on the

Material in the mold generated pressure is monitored so that the mold is opened a predetermined gap at a certain pressure corresponding to the degree of the desired filling.

6. The method according to any one of claims 1 to 5, characterized in that the detachment of the screen surface from the mold walls by air supply

Screen surface is supported.

7. The method according to any one of claims 1 to 6, characterized in that the detachment of the screen surface from the mold walls is supported by rotating at least one mold half with respect to the other about the longitudinal axis of the core.

8. The method according to any one of claims 1 to 7, characterized in that at least the mold half, which is seen in the feed direction of the core in front of the other mold half, is further divided into partial halves and that these partial halves are opened at different times from each other.

9. The method according to any one of claims 1 to 8, characterized in that in the manufacture of a composite insulator at its beginning and after the formation of the shield cover at its end on the core is interrupted for a predetermined length of the order of the material of the shield cover and that the insulator fittings are attached to these ends.

10. The method according to any one of claims 1 to 9, characterized in that a core has a length such that it can be used for the production of at least two composite insulators.

11. The method according to any one of claims 1 to 10, characterized in that in each case a subsequent core is connected to the preceding core to form a continuous rod or tube of great length for the continuous production of several composite insulators in succession.

12. The method according to any one of claims 1 to 11, characterized in that the parts of the shield cover already formed after the application of the material of the shield cover are thermally treated to produce the required material properties, while the material for forming the remaining parts of the shield cover or already is applied to the core to form the shield shell of the subsequent composite insulator.

13. The method according to any one of claims 1 to 11, characterized in that the screens are already thermally treated in the form.

14. The method according to claim 13, characterized in that the screens in the form undergo a thermal pretreatment and then separately a thermal treatment for the final curing of the screens.

15. The method according to any one of claims 12 or 14, characterized in that the thermal treatment of the material of the screen shells is carried out in a continuous furnace by means of hot air.

16. The method according to any one of claims 12 or 14, characterized in that the thermal treatment of the material of the shield cover is carried out by means of microwaves.

17. The method according to any one of claims 10 to 16, characterized in that at least one finished composite insulator, which is still connected via the core to the subsequent composite insulator, is supported by a transport device and that the subsequent composite insulator without support between the device for Applying the material of the shield cover and the transport device is kept.

18. The method according to any one of claims 1 to 17, characterized in that composite insulators are manufactured in succession with a different number of shields.

19. Device for producing composite insulators with a feed device for the rod-shaped or tubular core, devices for applying the material of the shielding shells to the core and for shaping the shields, and a heating device for the thermal treatment of the material, in particular for carrying out the method according to one of the claims 1 to 18, characterized in that the device (12) for applying the material (36) of the screen sheaths (3) has a shape (15, 15a, 15b) for shaping at least one ring-shaped screen

(5) is made of the material of the shield cover.

20. The apparatus according to claim 19, characterized in that the shape (15, 15a, 15b) for shaping a screen (5) in a first plane (48) perpendicular (49) to the longitudinal axis (26) of the core (102) of the to be produced Composite insulator (101) in two halves (46, 47; 46a, 47a; 46b, 47b) is divisible.

21. The apparatus according to claim 20, characterized in that seen in the feed direction (31) of the core (102) of the composite insulator to be produced (101) first half (46, 46a, 46b) of the mold (15, 15a, 15b) directly on the Mouth of the device (12) for applying the material (36)

5 shield covers (3) is arranged.

22. The apparatus of claim 20 or 21, characterized in that seen in the transport direction (31) of the core (102) of the composite insulator to be produced (101) second half (47) of the mold (15) in a second plane (53) is divisible that the second plane (53) is substantially perpendicular to the first

10 level (48) and that the partial halves (51, 52) of the mold half (47) are essentially axially (50) and radially (54) movable to the longitudinal axis (26) of the core (102).

23. The device according to one of claims 19 to 22, characterized in that the radial extent (R) of the mold space (69) in the mold (15, 15a,

15 15b) is greater than the radius (r) of the shaped screens (5).

24. Device according to one of claims 19 to 23, characterized in that the device (12) for applying the material (36) of the shielding sheaths (3) is followed by a heating section (16) for thermal treatment of the material (36).

20 25. The apparatus of claim 24, characterized in that the heating section (16) has a hot air recirculation fan (56, 57).

26. The apparatus according to claim 24, characterized in that the heating section has a source of high-energy radiation, preferably of microwaves.

27. The device according to one of claims 19 to 26, characterized in that the shape (15b) for shaping the screens (5) has a heating device (85, 86) at least for the thermal pretreatment of the material (36) of a screen cover (3).

28. Device according to one of claims 19 to 27, characterized in that the device (12) for applying the material (36) of the shielding sheaths (3) is preceded by a device (21) for connecting parts (19) together to form a rod (14) or tube of great length, which can be fed to the device (12), and that the cores (102) of the composite insulators (101) to be produced can be formed in the required length from the rod (14).

29. Device according to one of claims 19 to 28, characterized in that the device (12) for applying the material (36) of the shielding sheaths (3) with a length measuring device (43) on the rod (40) or tube is in operative connection and that the application of the material (36) to form the shield sheaths (3) depending on the feed (31) of the rod (14) or tube is controllable.

30. The device according to claim 29, characterized in that the device (12) for applying the material (36) to form the shield cover (3) in dependence on the feed (31) of the rod (14) or tube is controllable so that the End pieces (6, 7; 106) of the composite insulators (1, 101) remain free of the shield cover (3) over a predeterminable length (8, 9; 108) for connecting the fastening fittings.

31 Apparatus according to claim 29, characterized in that the speed (31) of the rod (14) or tube can be controlled in such a way that the end pieces (6, 7; 106) of the composite insulators (1, 101) are on a predeterminable one

The length (8, 9; 108) for connecting the fastening fittings must remain free of the shield cover (3).

32. Device according to one of claims 28 to 31, characterized in that the device (12) for applying the material (36) of the shield sheaths (3) is followed by a separating device (18) for separating finished composite insulators (1) of a predetermined length and in that the separating device (18) with the length measuring device (43) for measuring the length on the supplied rod (14) or

Pipe is in operative connection.

33. Device according to one of claims 19 to 32, characterized in that a transport device (17) is provided with which the finished composite insulators (1) on the circumference of their shields (5) can be transported supported and that the transport device (17) in such

Distance from the device (12) for applying the material (36) of the shielding sheaths (3) and, if appropriate, the heating section (16) is such that the composite insulators (101) which are still to be finished can be transported without support on the not yet hardened shielding sheaths (3) .