DE202009014606U1 - Device for producing composite plastic molded bodies and molded articles produced therewith - Google Patents

Abstract

Apparatus for producing composite plastic molded bodies having a plurality of part bodies emanating from a main body, with a divisible mold (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 mold (1) in the region of their highest points of the cavity vent bridges (15, 15 ').

Description

The The invention relates to a device for producing composite plastic molded bodies with a variety of outgoing from a body Partial bodies, with a divisible shape and an associated Closing unit for opening and closing the mold, with storage containers for each liquid Components of the plastic to be filled, with at least a mixing unit, if necessary a ground plunger and with supply lines for the reactive plastic mixture and a molded body produced therein.

to Production of plastic composite moldings such as Hollow insulators, it belongs to the prior art that hollow cylinder usually made of fiberglass-reinforced plastic (GRP) in one closed form with the desired part bodies, so-called. Umbrellas, to be poured. In doing so, the shape is several meters Length can reach, in horizontal position in a closing machine installed and opened and closed by this or during the filling and vulcanization process kept closed.

In terms of the mold temperatures, it is common to mold at a Temperature of about 80 ° C to fill. After the mold filling the mold temperature is increased to 110 ° C, to accelerate the vulcanization process. This typically takes between 20 and 60 minutes. After removal of the hollow insulator the shape is restored for the next shot Cooled to 80 ° C.

There The forms are made of steel, these can quite a few Be heavy. Often they have it to heat up and cool down over your own powerful Water heating. For the preparation of the plastic, in particular silicone, and Although preferred are Liquid Silicone Rubber (LSR), mixing and dosing systems used with a static mixer and barrel expression devices. The venting of the mold is often done by that the shape during the filling process without real Applying the closing force is kept closed, the actual closing force is only after completed Mold filling applied. This has the consequence that during the filling of the form a not insignificant upper weft (so-called "Flash") pressed out of the mold and carefully removed from the hollow insulator after demolding and must be disposed of. This means a not inconsiderable Rework.

From that Based on the invention, the object, the above mentioned and previously described in more detail device for manufacturing of plastic composite moldings so and educate that with a simple structural design an economic Production of absolutely bubble-free moldings such as hollow insulators is possible.

Solved This object is achieved in a device according to the Preamble of claim 1, characterized in that the shape in the area their highest points of the cavity vent bridges having. If according to another teaching of the invention means for Degassing of the liquid components and their mixture are provided, provide the means for degassing the liquid Components for pre-evacuation of these components, which has a very positive influence on the quality the later components has. In conjunction with the uniform venting over the special ventilation bridges is the manufacture of moldings such as hollow insulators 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 still have after leaving the static mixer an elevated 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.

To According to another teaching of the invention, the mold has a plurality of annular disc-like partial shapes for the formation of substantially perpendicular arranged to the longitudinal axis of the hollow cylinder screens on. The number of umbrellas per hollow cylinder is the purpose given, d. H. in particular by the predetermined by the threshold voltage Creepage path as overvoltage protection. Such is for example for a voltage of 100 kV an insulator length of about one meter necessary.

The employed in the device according to the invention Shape not only has the usual venting channels along the mold wall, but also over additional Venting bridges with specially designed geometry. According to another teaching of the invention, the vent bridges run namely from the upper wall of the cavity laterally up. The number of ventilation bridges corresponds to this preferably the number of partial bodies to be produced (umbrellas).

The in the form mounted ventilation bridges as well the use of comparatively high closing forces also during the mold filling phase reduce the post-removal work required to a minimum. A manual removal of the casting skins ("Flash") is not necessary because the remaining on the screen side Burrs from the webs created in the ventilation bridges can be removed by simply pulling off.

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

alternative It is also possible that the ventilation bridges over the vent line out to the top of the mold run. As in such an embodiment during the filling process the air can escape evenly upwards and by the pre-treatment of the components, the mixture of trapped air is liberated, is at the mold filling a much lower Closing force required. This is especially true when using a Masseplungers, because this - different as the dosing pumps - the pressure not only up but can also break down.

When Material for the molds are preferably special aluminum alloys provided that compared to steel over a material lower specific heat capacity at higher Have thermal conductivity. Through this Properties can be complex and a lot of energy need to be dispensed with water heating. thats why it is possible according to the invention as an agent to provide electrical heaters for heating. This type of mold making is therefore much cheaper than the usual Way used steel molds.

The special embodiment of the mold is based on a mold filling process, in which, starting from the filling opening, first The lower screen areas are filled before the silicone along the GRP pipe to the next screen. This has a significant impact on bladder clearance and the correct arrangement of the ventilation bridges.

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

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

A further embodiment according to the invention provides that a drive for approaching the sub-leads to those in the ground the form provided filling openings provided is. The sealing of the filling openings takes place thereby by appropriate plastic seals.

To Another teaching of the invention, the shape has at their ends removable end plates on which openings for receiving the Hollow cylinder may have. This particular for the case that the hollow cylinders are longer than the actual ones Shape, so that the production of the umbrellas to be cast must be done in several steps. Also, the face plates preferably carried out split to facilitate demolding.

In a further embodiment of the invention are means for heating the reservoir, the Mixing unit, the form and / or the supply lines provided. By increasing the temperature of the components in the respective containers as well as by the use of heated lines for heating or cooling static mixers (up to about 80 ° C) can be achieved significant shortening of 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.

Of the the static mixer preferred downstream Masseplunger allowed to set constant, optimally adjusted pressures in the mold. This leads in connection with the special embodiment of Form by the required closing forces to nearly "Flash" -free Isolators that require virtually no post-processing.

The The invention also relates to a molding which is in a device according to the invention is produced, wherein the shaped body from a hollow cylinder with cast Shields manufactured hollow insulator is.

Thereby, that the silicones used for shielding the hollow cylinder Be relatively expensive, provides another teaching of the invention before that added a filler to the plastic used is. As a filler, for example, quartz, alumina trihydrate, Alumina or the like can be used.

Becomes such a filler added are the means of degassing the liquid components for pre-evacuation compulsory use of these components, as an addition of fillers without vacuum conditioning is not possible, because at one Mixing process without vacuum much air would be stirred and the resulting foaming of the reactive mixture causes blistering could not prevent in the molding.

The Addition of fillers has the further advantage that the Thermal conductivity increases, what the cycle time shortened. 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 will be injected Compound considerably cheaper.

Here are savings between 15% and 40% on the material price (each according to filler and filler content) achievable.

The Invention will now be described with reference to a preferred one Embodiment illustrative drawing closer explained. 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 reliably avoided. 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 it is understood that the drawings are only a preferred embodiment represent, as with the inventive Device any shaped body, such as cable fittings, make, where it depends on an extreme bladder freedom.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over 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. Device according to claim 1, characterized in that that for pressure build-up of the pressed into the mold reactive mixture a Masseplunger is provided. Device according to claims 1 or 2, characterized characterized in that means for degassing the liquid Components are provided and 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 as material for the mold Aluminum alloys are provided. Device according to one of claims 1 to 9, characterized by the use of a hollow cylinder (H) as a basic body, the length of which is a multiple its diameter is. 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. Device according to claim 11, characterized in that 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 ). Device according to claim 17, characterized in that 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 molded body from a hollow cylinder (H) with cast Shields (S) manufactured hollow insulator (HI) is. Shaped body according to claim 19, characterized that added a filler to the plastic used is. Shaped body according to claim 20, characterized that is provided as a filler quartz powder. Shaped body according to claim 20, characterized that is provided as filler alumina trihydrate. Shaped body according to claim 20, characterized that is provided as filler alumina.