DE2362161A1 - Hot duct injection moulder for multiple small articles - has additional insulating annulus around heat conducting core - Google Patents

Abstract

A hot duct injection moulding machine comprises a hot duct distributor plate clamped between a mould plate and a clamping plate; the distributor plate comprises a number of smooth-bore transverse passages, in each of which there is seated a core cylinder having a flange at the front of the distributor plate and a screwed-on nut at the back. Each core cylinder contains a screwed-in, heat-conducting core which itself contains the sprue duct and projects some way out of the heat distributor plate into the nozzle unit. There is thus an intermediate, annular space between the outer face of this heat-conducting core and the inner face of the nozzle unit, all as in the Parent Patent, in which it was intended that this annular space should be filled with partially set injected material which would thus constitute a thermal insulation. In this Parent of Addn, the heat-conducting core has a thermally insulating annular chamber in the vicinity of its cylindrical surface, esp. constituted of turned-in channels forming a setback from the cylindrical surface and themselves covered by a cylindrical sleeve. This provides the necessary additional insulating effect. When the penetration of the heat-conducting core into the nozzle unit is relatively long.

Description

DR. ING. UlPL PHYS. H. STURlES

PATENTANWÄLTE ■ _ _iA “. _ _β

DIPL. ING. P. EICHLER

56 WUPPERTAL 2, BRAHMSSTRASSE 29

Dec 12, 1973

Company Strack-Norma GmbH, 56 Wuppertal 1, Friedrich-Ebert-Str.

"Hot runner injection molding tool" ■ (2nd addendum to patent application P 21 60 535.6)

Subject of patent application P 21 60 535.6 is a hot-runner injection molding tool seated, held by means of the cylinder bore edges engaging behind Einspannflansche and directly abstützender on the platen clamping nuts core cylinders is provided with, arranged between a Pormund a platen _r heated hot runner manifold plate which X IND with smooth continuous cylinder bores therein , which each carry a screwed-in, axially penetrated by a ground conduction heat conducting core, which protrudes at a distance into the nozzle body of the mold plate and thus forms a heat-insulating space to be filled by partially solidifying injection molding compound.

Such a hot runner injection molding tool is distinguished especially because of its compact design, made of distribution plate and fitted core cylinders with heat conducting cores screwed into them existing hot runner block, which can be used for a even heat distribution as well as for optimal

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Dissipation of the considerable pressure forces ensures and is therefore largely free of distortion. Also are with him the ground ducts sealed in the best possible way. In addition, the hot runner block can be precisely dimensioned and can also be easily assembled or disassembled between the mold and the clamping plate.

During the main registration, the thermal insulation takes place between the hot heat conducting core and the nozzle body, which is to be kept as cold as possible, or the mold plate solely through the existing between the nozzle body and the heat conducting core, mostly filling up with solidifying injection molding compound Space. As long as the heat conducting core is not too protruding deep into the nozzle body, this aforementioned thermal insulation is sufficient. But that is no longer the case when the heat conducting core must have a relatively wide axial extension, as is the case, for example, with relatively deep trained nozzle bodies is necessary because then over the correspondingly long ring-like space and the solidified injection molding compound located therein too much heat flows outward into the nozzle body or into the mold plate, hence the tip of the heat conducting core protruding into the nozzle opening or into the mold cavity is no longer sufficient Receives heat supply. That would then only be through additional heating of the heat conducting cores, for example with the help of appropriate Rod or ring heating possible.

The present additional invention is therefore the task based on the hot runner injection molding tool according to the main patent

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registration to improve and perfect that an even more effective thermal insulation between its heat conducting cores and the associated nozzle bodies or the mold plate is achieved. This object is achieved according to the invention solved that a thermally insulating annular chamber is provided in the heat conducting core near its surface. This will advantageously formed by a cylindrical recess made on the circumference of the heat conducting core, which extends outwards through a sleeve is covered, which is made of steel, in particular V2A steel can exist.

Due to the advantageous use of air as a heat insulating medium filled annular chamber in the vicinity of the surface of the heat conducting core, this is largely protected against heat transport taking place radially outwards, so that not only corresponding Heat losses can be avoided, but so does the heat conducting core can be dimensioned correspondingly longer axially without causing difficulties in terms of keeping the * plastic compound passing through the nozzle opening. Rather, the plastic compound remains even with greater axial stretches of the heat conducting core at its tip or in Area of the nozzle opening sufficiently flowable without an additional heating of the heat conducting core is necessary were.

In the drawing , an exemplary embodiment of a hot runner injection molding tool designed according to the present additional invention is shown in a partial sectional view.

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The hot runner injection molding tool shown consists essentially of the several inserted nozzle bodies 1 containing mold plate 2, the platen 3 and the heatable arranged between the aforementioned plates Hot runner distributor plate 4 and spacer plates, not shown. The distribution plate is equipped with several smoothly continuous, so provided unstepped bores 5, in each of which a core cylinder 6 is fitted, which the edges the cylinder bore 5 with its clamping flange 6 · on the one hand and a correspondingly protruding, screwed-on clamping nut 7 on the other hand engages behind. The clamping nut 7 is supported directly on the clamping plate 3.

A threaded bore 6 ″ is provided in the core cylinder 6, into which the heat conducting core 8, which is provided with a corresponding threaded part 8 ′, is screwed. This heat-conducting core 8 is preferably made of silver, that is to say of a material that conducts heat particularly well. The heat conducting core 8 is axially penetrated by the valveless ground conduit 9, which on the one hand connects to the ground conduit 6 ″ bent at right angles in the core cylinder 6 and, on the other hand, opens via the two branch channels 9 ′ into the space 10 existing between the heat conduction core 8 and the nozzle body 1, which fills with injection compound at the beginning of the spraying process, which for the most part solidifies and thus forms good thermal insulation between the heat conducting core and the nozzle body 1, which is to be kept as cool as possible, for further spraying processes.

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The adjusting needle 11, which is adjustably mounted in the latter and which is preferably made of steel, extends through the ground conduction channel 9 of the heat conducting core 8 and also through the core cylinder 6. The adjusting needle 11 protrudes with its tip 1.1 into the nozzle opening I ¹ present in the nozzle body 1. At its other end, the adjusting ^{needle 11 is} provided with a widened head II 11, which is supported on the one hand on the adjusting screw 12 located in the core cylinder 6 and on the other hand on the counter screw 13 located in the clamping nut 7. Both the adjusting screw 12 and the counter screw 13 are each provided with a polygonal socket "12. '" or 13 ', which are preferably of the same design, i.e. can be operated with one and the same ^{socket wrench. By appropriately adjusting the adjusting needle 11 axially by means of the adjusting screw 12 and the counter screw 13, the tip II 1 of} the adjusting needle with respect to the nozzle opening 1 'and also with respect to the mold cavity can be adjusted so that the injection-molded part can always be produced with the smallest possible injection point, regardless of its plastic properties.

To the heat conducting core 8 against heat losses as much as possible To protect and train him as long as possible, he is close to his surface with a heat insulating annular chamber 14 provided. These preferably Ring chamber 14 filled with air as a good heat insulating medium is closed by a corresponding cylindrical recess on the.

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Surface of the heat conducting core 8 is formed, which is covered by the sleeve 15 to the outside. The latter is made of steel, especially made of V2A steel. Through this air-filled annular chamber 14, in addition to the thermal insulation, the further effective thermal insulation is formed by the partially solidified injection molding compound present in the space 10 of the heat conducting core 8 guaranteed, so that the latter are also relatively long or deep in the nozzle body 1 can protrude. Without being equipped with an additional electric rod or ring heater to have to be.

To the considerable extent exerted on the sleeve 15 by the solidifying plastic mass in the space 10 To be able to absorb pressures better, a corresponding support of the sleeve 15 is recommended in the annular chamber 14 provided support ribs 16. These can for example - as in the case shown - in the form of a incorporated into the relevant area of the heat conducting core 8, be formed ended screw thread.

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Claims (5)

23B2TS1 claims (\ ■■ ■ ■; ■ '■; :: ■ 1.) Hot runner injection mold with one between one Heatable mold and a clamping plate arranged Hot runner manifold plate, which is made with smooth, continuous' Cylinder bores and clamping flanges seated in them, gripping the cylinder bore edges and directly supported on the clamping plate Locking nuts held core cylinders is provided, each one screwed in, axially from a ground conduit Carry penetrated heat conducting core, which protrudes at a distance into the nozzle body of the mold plate and thus a partially solidifying injection molding compound to be filled, heat-insulating space forms, according to patent application P 21 60 535.6, - d a ■ d u r c h g e k e η η ze i eh η et, that in the heat conducting core (8) in the vicinity of its surface a heat-insulating annular chamber (1.4) is provided, 2. Hot runner injection molding tool according to claim 1, d ä d u r c h characterized in that the heat conducting core (8) with a cylindrical turning (14) forming the annular chamber provided and this covered to the outside by a sleeve (15) XSt. _: 509826/0 407 -M- * E * 3. Hot runner injection molding tool according to claims 1 and 2, characterized in that the
Cover sleeve (15) made of steel, in particular V2A steel. 4. hot runner injection molding tool according to claims 1 to 3, characterized in that the
Annular chamber (14) is filled with air as a heat insulating medium. 5. hot runner injection molding tool according to claims 1 to 4, characterized in that in the annular chamber (14) support ribs (16) for the cover sleeve (15) are provided, e.g. in the form of a screw thread worked into the relevant area of the heat conducting core (8). ■ 50982 6/0 U 07