DE102009051155A1 - Device for manufacturing plastic composite molded body, has multiple partial bodies outputted from base body, divisible mold and associated closing unit for opening and closing mold - Google Patents

Abstract

The device has multiple partial bodies outputted from a base body, a divisible mold (1) and an associated closing unit for opening and closing the mold. Storage vessels are provided for individual liquid components of plastic. The mold has aeration bridges within range of highest points of a cavity. An independent claim is also included for a molded body that is provided as filler aluminum oxide tri-hydrate and filler aluminum oxide.

Description

The invention relates to a device for producing composite plastic molded articles with a plurality of outgoing from a main body part bodies, with a divisible mold and an associated closing unit for opening and closing the mold, with storage containers for the individual liquid components of the plastic to be filled, with at least a mixing unit, if necessary. A Masseplunger and with leads for the reactive plastic mixture and a molded body produced therein.

For the production of plastic composite moldings such as hollow insulators, it belongs to the state of the art that hollow cylinders are usually made of glass fiber reinforced plastic (GRP) in a closed mold with the desired part bodies, so-called. Screens are encapsulated. In this case, the mold, which can reach several meters in length, installed in a horizontal position in a closing machine and opened and closed by this or kept closed during the filling and vulcanization process.

With regard to the mold temperatures, it is customary to fill the mold at a temperature of about 80 ° C. After mold filling, the mold temperature is raised to 110 ° C to accelerate the vulcanization process. This typically takes between 20 and 60 minutes. After removal of the hollow insulator, the mold is cooled again to 80 ° C. for the next shot.

Since the molds are made of steel, they can be quite a few tons heavy. For this reason, they often have their own powerful water heater for heating and cooling. For the preparation of the plastic, in particular silicone, preferably liquid silicone rubber (LSR), mixing and dosing with a static mixer and Fassausdrück devices are used. The venting of the mold is often done in that the mold is kept closed during the filling process without actually applying the closing force, the actual closing force is applied only after completion of mold filling. As a result, a considerable surplus (so-called "flash") has to be pressed out of the mold during filling of the mold and, after removal from the mold, has to be carefully separated from the hollow insulator and disposed of. This means a not inconsiderable rework.

Based on this, the invention has the object, the above-mentioned and previously described in more detail device for producing composite plastic moldings to design and refine that with a simple construction, an economical production of absolutely bubble-free moldings such as hollow insulators is possible.

This object is achieved in a device according to the preamble of claim 1, characterized in that the mold has venting bridges in the region of their highest points of the cavity. According to another teaching of the invention, means are provided for degassing the liquid components and for mixing them, the means for degassing the liquid components for pre-evacuation of these components, which has a very positive influence on the quality of the later components. In conjunction with the uniform ventilation via the special ventilation bridges, the production of moldings such as hollow insulators is possible, which are absolutely bubble-free from the first shot.

The absence of bubbles is an essential criterion for the use of hollow insulators in order to achieve the required properties. These properties are from the DIN standard EN 61462: 2007 established. This standard applies to composite hollow insulators consisting of a load-bearing insulating tube made of plastics-impregnated fibers, a shielding sheath (outside the insulating tube) of resilient polymeric material (for example silicone or ethylene-propylene and metal fittings at the ends of the insulating tube) They are used in indoor and outdoor electrical equipment, either with alternating current (rated voltage> 1000 V) or in DC (rated voltage> 1500 V) for general use (pressureless) or for use with a permanent gas filling (pressurized). operate.

Thus, according to the invention, the storage containers are already designed to be evacuable. The reservoirs each have a metering pump and check valves in the lines to the mixing unit, preferably a static mixer. The static mixer is preferably followed by a ground plunger, which maintains a constant, adjustable pressure on the ground line to the pouring valves when filled, which can not only be constructed but also reduced. It also allows a constant, uninterrupted mass flow during mold filling. When using higher-viscosity LSR components, the temperature in the storage tanks rises to approx. 50 to 60 ° C due to the friction heat of the agitators. Evacuable storage containers are already known ( DE 100 18 856 C1 ).

The heated components have even after leaving the static mixer yet another increased temperature, which leads to a quite desirable shortening of the mold opening times. The device according to the invention has in a further embodiment of the invention means for heating the reservoir, the mixing unit, the mold and / or the supply line. The static mixer and the also reactive mixture containing Masseplunger are made in heatable and coolable design to cool the mixture, for example, during a production break over the weekend, to extend its pot life significantly.

According to a further teaching of the invention, the mold has a multiplicity of annular disk-like partial shapes for forming screens arranged substantially perpendicular to the longitudinal axis of the hollow cylinder. The number of screens per hollow cylinder is specified by the purpose, d. H. in particular by the predetermined by the threshold voltage creepage as overvoltage protection. For example, an insulator length of about one meter is necessary for a voltage of 100 kV.

The mold used in the device according to the invention not only has the usual venting channels along the mold wall, but also additional venting bridges with specially designed geometry. According to a further teaching of the invention, the vent bridges namely extend laterally upward from the upper wall of the cavity. The number of vent bridges preferably corresponds to the number of partial bodies to be produced (screens).

The venting bridges mounted in the mold as well as the use of comparatively high closing forces, even during the mold filling phase, reduce the reworking required after demolding to a minimum. A manual removal of the casting skins ("flash") is not required because the burrs remaining on the shield side can be removed from the webs created in the ventilation bridges by simply pulling off.

According to a further teaching of the invention, the vent bridges first end in a vent line following the contour of the mold and more preferably run between the vent line and the top of the mold. In this way it is possible to evenly fill the mold with bubble-free silicone mixture.

Alternatively, it is also possible that the vent bridges extend beyond the vent line to the top of the mold. Since the air can escape evenly upwards in such an embodiment during the filling process and the mixture of air inclusions is freed by the pretreatment of the components, a significantly lower closing force is required in the mold filling. This is especially true when using a ground plunger, as this - unlike the metering pumps - the pressure not only up but can also reduce.

As the material for the molds special aluminum alloys are preferably provided, which have a much lower specific heat capacity and higher heat conductivity compared to steel. These properties make it possible to dispense with expensive and much energy-requiring water heating. Therefore, it is possible according to the invention to provide electric heaters as means for heating. This type of mold making is therefore much cheaper than the steel molds commonly used.

The special design of the mold is based on a mold filling process in which, starting from the filling opening, the lower shield areas are first filled before the silicone flows along the GFRP pipe to the next screen. This has a significant influence on the freedom from bubbles and the correct arrangement of the ventilation bridges.

Another teaching of the invention provides that a hollow cylinder is used as the base body whose length is a multiple of its diameter. The length of the hollow cylinder can also exceed the length of the mold.

In a further embodiment of the invention, the supply line between Masseplunger and form a division into several sub-leads. The partial supply lines end at a filling opening (so-called injection point) at the bottom of the mold, wherein each injection point can supply about 10 to 20 umbrellas.

A further embodiment according to the invention provides that a drive is provided for approaching the partial supply lines to the filling openings provided in the bottom of the mold. The sealing of the filling openings is carried out by appropriate plastic seals.

According to a further teaching of the invention, the mold has on its end faces removable end plates, which may have openings for receiving the hollow cylinder. This especially for the case that the hollow cylinder are longer than the actual shape, so that the production of the umbrellas to be cast must be done in several steps. Also, the end plates are preferably designed split to facilitate demolding.

In a further embodiment of the invention, means for heating the storage container, the mixing unit, the mold and / or the supply lines are provided. By raising the temperature of the Components in the respective containers as well as by the use of heated lines to heating or coolable static mixers (up to approx. 80 ° C) can be achieved considerable shortenings of the mold opening times. Increased injection temperatures also lead, depending on the material, to lower mass viscosities, which positively supports the mold filling process.

Through the use of aluminum alloys, such as the alloy EN AW 7022 (AlZn5Mg3Cu), as a mold material according to the invention only an electric heater is required, so that can be completely dispensed with the usual, energy-intensive water heating.

The mass plunger, which is preferably connected downstream of the static mixer, makes it possible to set constant, optimally adapted pressures in the mold. This, in conjunction with the special design of the mold by the required closing forces to almost "flash" -free insulators that require virtually no reworking.

The invention also relates to a molded article which is produced in a device according to the invention, wherein the molded article is a hollow insulator produced from a hollow cylinder with cast-walled screens.

Due to the fact that the silicones which are used for shielding the hollow cylinders are relatively expensive, a further teaching of the invention provides that a filler is added to the plastic used. As the filler, for example, quartz flour, alumina trihydrate, alumina or the like can be used.

If such a filler is added, the means for degassing the liquid components for pre-evacuation of these components are mandatory because an addition of fillers without vacuum processing is not possible because in a mixing process without vacuum much air would be stirred and the resulting Foaming of the reactive mixture could not prevent bubble formation in the molding.

The addition of fillers has the further advantage that the thermal conductivity increases, which shortens the cycle time. Also, the tracking resistance is improved. Through the use of vacuum technology in conjunction with the device according to the invention and the addition of (cheap) fillers, the compound to be injected becomes considerably less expensive.

Here, savings of between 15% and 40% on the material price (depending on the filler and filler content) can be achieved.

The invention will be explained in more detail with reference to a drawing showing only a preferred embodiment. In the drawing show

1 a device according to the invention in perspective view,

2 a side view of the mold used, wherein the filling lines are moved up to the filling openings,

3 an enlarged view of the mold in the region of a filling opening,

4 a further increase in the area of the ventilation bridges, wherein 4a the side view and 4b in cross-section along the line IVb-IVb represents and

5 a composite hollow insulator made with the mold according to the invention.

In the 1 simplified device according to the invention consists initially of a divisible form, of which only one mold half 1 is shown schematically. The mold half 1 is on a fixed platen 2 arranged. The second mold half, not shown, is on a movable platen 3 attached. For the sake of simplicity, the end plates closing the elongated shape at their end faces are in FIG 1 not shown. hydraulic cylinders 4 ensure the application of the necessary closing pressure. Below the mold halves 1 are two height-adjustable supply lines 5 recognizable which of a drive, not shown on the bottom of the mold 1 located filling openings can be moved up. Finally is 1 another rail 6 can be seen, at which an unspecified recording unit is moved longitudinally to the demolded molded body 7 from the closing unit to transport.

2 now shows the mold half 1 in side view. Here you can see a schematically inserted (dashed) inserted hollow cylinder H. The form 1 is at its front sides of the hollow cylinder H adapted face plates 8th locked.

In 2 are for better explanation in the illustrated and thus preferred embodiment, both filling lines 5 to the shape 1 shown approached. The necessary sealing are the filling lines 5 at its top with hollow conical plastic seals 9 Mistake. Above all, the seals ensure that no air can be sucked into the mold from outside. Also, leakage of reactive plastic mass during the filling process can be so reliably avoid. Furthermore, the filling lines 5 with a slide 10 Provided with unspecified border provided so that between the shots vulcanized plastic material located below the open chute end waste container 11 can be flushed, to the radiation of the hot mold is used.

In 2 one recognizes further clearly that the mold half 1 over a plurality of perpendicular to the longitudinal axis of the hollow cylinder H extending part forms 12 has, which serve for the production of the later screens of the composite hollow insulator. It can also be seen that the mold half 1 from a multitude of collinearly arranged segments 13 consists. These segments combined to form 13 are preferably made of an aluminum alloy, which combine the advantages of low weight, price, low specific heat capacity and high thermal conductivity. In addition, the segment design allows the shape for the production of different length moldings relatively easy to change in length.

3 now shows a further enlargement of a section of the mold half 1 , One recognizes in the lower area a filling opening 5 ' , which are in a partial form 12 ' ends. Along the cavity contour of the mold half 1 or the partial forms 12 runs a circumferential vent line 14a . 14b and 14c where only the lower area of the filling opening 5 ' containing segment 13 ' has no line.

According to the invention are now in the upper part of the part shapes 12 vent bridges 15 intended. These run initially laterally upward, in the illustrated preferred embodiment and to the left above, and end there in the upper circumferential vent line 14c , Above that, they then set themselves as ventilation bridges 15 ' up to the top of the mold half 1 continued. In this way, it is ensured that the rising in the filling silicone mixture can displace the air contained in the mold evenly upwards. The at the upper edge of the part form 12 located ventilation bridges 15 ensure that a bubble-free and void-free filling of the mold can be achieved up to the highest point.

4a shows once again an enlargement of the form 1 in the area of a partial form 12 which of two adjacent segments 13 is formed. You can clearly see the circumferential vent line 14c whose cross-section is in 4b is reproduced. The obliquely laterally upward venting bridge 15 allows a filling of the part form 12 to the top, because the escaping air through the vent line 14c and the extended vent bridge 15 ' can leave the closed form. After removal from the mold, one of the vent bridge is located on each screen 15 formed web R.

Finally shows 5 a composite hollow insulator HI produced with the device according to the invention. It can be seen clearly arranged around the hollow cylinder H umbrellas S, which, as can be seen from the magnification, all have a small ridge R. The web R does not affect the function of the composite hollow insulator HI and serves rather as an indicator for a bubble and void-free filling of the mold.

It is understood that the drawings represent only a preferred embodiment, since can be produced with the device according to the invention any shaped body, such as cable sets, where it depends on extreme freedom from bubbles.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10018856 C1 [0008]

Cited non-patent literature

• DIN standard EN 61462: 2007 [0007]
• EN AW 7022 [0022]

Claims (23)

Apparatus for producing composite plastic molded bodies having a multiplicity of part bodies emanating from a basic body, having a divisible form (US Pat. 1 ) and an associated closing unit for opening and closing the mold, with storage containers for the individual liquid components of the plastic to be filled, with at least one mixing unit and with supply lines ( 5 ) for the reactive plastic mixture, characterized in that the shape ( 1 ) in the area of their highest points of the cavity vent bridges ( 15 . 15 ' ) having. Apparatus according to claim 1, characterized in that a mass plunger is provided for pressure build-up of the pressed into the mold reactive mixture. Device according to claims 1 or 2, characterized in that means are provided for degassing the liquid components and for their mixture. Device according to one of claims 1 to 3, characterized in that the shape ( 1 ) a plurality of annular disc-like part shapes ( 12 ) for the formation of substantially perpendicular to the longitudinal axis of the hollow cylinder (H) arranged screens (S). Device according to one of claims 1 to 4, characterized in that the ventilation bridges ( 15 ) extend laterally upward from the upper wall of the cavity. Device according to one of claims 1 to 5, characterized in that the number of ventilation bridges ( 15 . 15 ' ) the number of partial shapes to be produced ( 12 ) corresponds. Device according to one of claims 1 to 6, characterized in that the ventilation bridges ( 15 ) in one of the contours of the shape ( 1 ) following deaeration line ( 14c ) end up. Device according to one of claims 1 to 6, characterized in that the ventilation bridges ( 15 ' ) via the vent line ( 14c ) out to the top of the mold ( 1 ). Device according to one of claims 1 to 8, characterized in that are provided as the material for the mold aluminum alloys. Device according to one of claims 1 to 9, characterized by the use of a hollow cylinder (H) as the base body, the length of which is a multiple of its diameter. Device according to claim 2 and 9 or 10, characterized in that the supply line ( 5 ) between ground plunger and shape ( 1 ) has a division into several sub-leads. Apparatus according to claim 11, characterized in that two partial supply lines are provided. Apparatus according to claim 11 or 12, characterized in that a drive for approaching the partial supply lines in the bottom of the mold ( 1 ) provided filling openings ( 5 ' ) is provided. Device according to one of claims 9 to 13, characterized in that the shape ( 1 ) removable end plates ( 8th ) having. Apparatus according to claim 14, characterized in that the end plates ( 8th ) have an opening for receiving the hollow cylinder (H). Apparatus according to claim 15, characterized in that the end plates ( 8th ) are executed shared. Device according to one of claims 1 to 16, characterized by means for heating the storage container, the mixing unit, the mold ( 1 ) and / or the supply lines ( 5 ). Apparatus according to claim 17, characterized in that as means for heating at least one electric heater is provided. Shaped body produced in a device according to one of claims 1 to 18, characterized in that the shaped body is a hollow insulator (HI) produced from a hollow cylinder (H) with cast-on sheds (S). Shaped body according to claim 19, characterized in that a filler is added to the plastic used. Shaped body according to claim 20, characterized in that quartz flour is provided as filler. Shaped body according to claim 20, characterized in that it is provided as filler alumina trihydrate. Shaped body according to claim 20, characterized in that it is provided as filler alumina.

Images