WO1995002494A1

WO1995002494A1 - Cold-runner block for processing elastomers

Info

Publication number: WO1995002494A1
Application number: PCT/IB1994/000212
Authority: WO
Inventors: Wilfried Holzmann
Original assignee: Stefan Pfaff Werkzeug- Und Formenbau Gmbh & Co. Kg
Priority date: 1993-07-15
Filing date: 1994-07-13
Publication date: 1995-01-26
Also published as: DE9310529U1

Abstract

In a cold-runner block for processing elastomers, the tempered elastomer is injected under high pressure into a mould through a row of parallel exchangeable nozzle bodies (8) held by clamping means. A cold-runner beam (1) in the area of the nozzle channels (7) has threaded bores (18) and the nozzle bodies (8), which consist each of a sprue nozzle (15) and of a cooling jacket (9), have a corresponding threaded projection (17) by means of which they are screwed into the nozzle channels (7).

Description

Cold runner block for processing elastomers

The invention relates to a cold runner block for the

Processing of elastomers, preferably rubber compounds.

Cold runner blocks of this type are used for the injection molding of elastomeric mixtures, the tempered rubber mixture being injected into a mold under high pressure via a series of nozzle bodies arranged in parallel on a cold runner block. For this purpose, it is known to provide the cold runner block with appropriate cooling passages in order to ensure adequate cooling.

In addition, it is known to also provide the nozzle bodies with appropriate cooling channels in order to also cool the nozzle bodies sufficiently, if possible over the entire length. In addition, it is known to have one in the sprue nozzle assigned to the nozzle body

Sliding nozzle to be arranged.

So far, the nozzle body had been attached to the cold runner beam of the cold runner block by means of plug-in connections. Here, the nozzle body had a sleeve-shaped attachment, which was inserted into an assigned, divided bore in the cold runner block. In order to establish the plug connection, it was known to split the cold runner block into two parts in order to open the bore; the nozzle body with its sleeve-like attachment was then inserted into the opened bore, and the cold runner block was closed again with its two parts, in order to ensure a firm connection of the nozzle body to the cold runner block.

ERSAΓZBLÄΓT (RULE 26) However, the disadvantage of this known connector was the risk of a leak. As a result of the corresponding thrust forces which act on the nozzle body when the rubber mixture is injected through the sprue channel through the nozzle body, there were strong shear loads in the area of the attachment of the nozzle body in the cold runner block, as a result of which the described plug connection was subjected to high loads and became leaky. As a result, spray compound was lost and there was a thermal imbalance when injecting into the injection mold.

Furthermore, it was known to design the nozzle body with corresponding flanges, with screws reaching through the flanges, which screws were screwed into the associated bores of the cold runner beam. This type of screw connection has the disadvantage that a certain minimum distance between a plurality of nozzle bodies arranged in parallel on a cold runner beam is required, which prevents the nozzle bodies from being arranged next to one another at a relatively close distance.

Therefore you have to switch to larger molds and make larger injection presses available.

Another disadvantage of the known screw connection was that the sprue nozzle in turn only reached into the sprue channel with a plug-in attachment, which in turn caused the risk of leaks.

The invention is therefore based on the object of further developing a cold runner block of the type mentioned at the outset in such a way that the nozzle bodies can be easily replaced on the cold runner without the risk of leaks occurring.

REPLACEMENT BLUE (RULE 26) bars are held.

To achieve the object, the invention is characterized by the technical teaching of claim 1.

An essential feature of the invention is that the sprue nozzle assigned to the nozzle body has a threaded attachment which is screwed into an assigned threaded bore in the region of the nozzle channel of the cold runner beam.

This screw connection has the essential advantage that the parts that are assigned to one another and are to be sealed against one another (namely the sprue channel in the cold runner beam and the sprue nozzle) are connected to one another by a screw connection.

There is no longer any risk of leakage because the screw connection is absolutely tight and can also transmit high thrust forces. There is therefore no longer any risk of rubber compound exiting the cold runner beam via appropriate sealing gaps, because the screw connection is absolutely tight and transmits high loads.

Even when high shear forces are transmitted, there is therefore no risk of leaks.

With the screw connection described, in which the sprue nozzle is directly screwed into the associated cold runner beam, there is the further advantage that corresponding counter-holding means or clamping means for bracing the nozzle body on the cold runner beam can be omitted.

ERSÄΓZBLAΓT (RULE 26) In the prior art, a corresponding shaped plate or a counter plate was used with which the nozzle body was held in front, this counter plate being fastened to the cold runner beam with the aid of a screw connection. Such clamping means can now be omitted according to the invention.

Otherwise, the thermal behavior of the nozzle body is also adversely affected by the use of a clamping plate according to the prior art, because this clamping plate has its own thermal capacity and the entire nozzle body is therefore difficult to cool. These disadvantages are eliminated in the present innovation, because according to the innovation the nozzle body now only consists of two parts, namely the sprue nozzle and the cooling jacket radially surrounding the sprue nozzle.

It is preferred here if the cooling jacket is attached to the sprue nozzle in an easily detachable manner. Several connections can be considered here as an easily detachable connection.

In a first preferred embodiment it is provided that transverse bores are arranged in the cooling jacket, into which grub screws engage, which engage with their bolt-side end in an associated annular groove on the outer circumference of the sprue nozzle.

It is necessary here to hold the cooling channel in a sealing manner by means of corresponding O-rings on its opposing end faces, on the one hand on the underside of the cold runner bar and on the other hand on the front of the sprue nozzle.

In another embodiment of the present invention, it is provided that the cooling jacket is attached to the sprue nozzle with a corresponding screw connection.

ERSÄΓZBLÄΓT RULE 26 is screwed.

Here, the cooling jacket has a corresponding internal thread which engages in an assigned external thread of the sprue nozzle.

Instead of the screw connection described here, crimp connections can also be used for the connection between the cooling channel and the sprue nozzle. Such a crimp connection in turn presupposes a clamping plate, which tightly seals the cooling jacket against the underside of the cold runner beam.

With the given technical teaching there is now for the first time the advantage that with such a fastening of a nozzle body to a cold runner beam it is now possible to be able to inject the injection molding compound freely into an open mold without corresponding tensioning or counter-holding means to have to use on the nozzle body. The screw connection described is so resilient that there is no need for additional clamping plates or counter-holding means. In a manner known per se, a sliding nozzle is used in the sprue nozzle, which is calibrated and via which the spray compound is dispensed. In the end region of the sliding nozzle, an insulating body is attached, which is attached to the sliding nozzle and which rests with its rear end on the assigned front end of the sprue nozzle. This insulating body consists of a thermally insulating material and lies against the sprue hole of the tool mold and brings about the thermal separation between the sliding nozzle and the tool mold. The insulating body could also be omitted in the event that, instead of being injected into a mold, it is first injected into a sub-distributor, which in turn is then injected into the

SPARE BLADES (RULE 26) Injection mold injected.

The subject matter of the present invention results not only from the subject matter of the individual patent claims, but also from the combination of the individual patent claims with one another.

All of the information and features disclosed in the documents, including the summary, in particular the spatial design shown in the drawings are claimed to be essential to the invention, insofar as they are new to the prior art, individually or in combination.

In the following the invention is based on only one

Execution path illustrating drawings explained in more detail. Further essential features and advantages of the invention emerge from the drawings and their description.

Show it:

FIG. 1: bottom view of a cold runner block in the direction of arrow I in FIG. 2,

Figure 2: Section along the line II-II in Figure 1,

Figure 3: Section along the line III-III in Figure 1.

The cold runner block according to the innovation essentially consists of a cold runner beam 1, which consists of a high-alloy tool steel. In a manner known per se, the cold runner bar has a vertical Gußkanal on, which opens into an approximately central, extending over the entire length of the cold runner beam 1, runner 6. The sprue channel 6 is closed at the end by corresponding deflection plugs 25. The deflection plug 25 is designed as a plug-in insert, which is secured against axial displacement in the sprue by a threaded plug 27, which in turn is screwed into an associated threaded hole in the cold runner beam 1. To prevent rotation of the

Deflection plug is also provided a locking screw 26 which is screwed into an associated threaded hole in the cold runner beam 1 and which is supported with its bolt-side end on the deflection plug 25.

To cool the cold runner bar is at least one cooling connection piece 4, which opens into assigned cooling channels 5 in the cold runner bar 1. The cooling water outlet takes place via a further cooling connection piece 3.

In a manner known per se, the cooling channels 5 in the cold runner bar are arranged in two levels (see FIG. 3). The sprue channel 6, which extends in the longitudinal axis of the cold runner beam 1, opens into associated nozzle channels 7, which in turn open directly into channels which are arranged in nozzle bodies 8.

It is essential here that a number of nozzle bodies 8 are held on the cold runner bar 1 in an easily replaceable manner by the screw connections to be described later.

Each nozzle body 8 consists of an inner one Sprue nozzle 15, which has an upper threaded shoulder 17 with which it is screwed into an associated threaded bore 18 in the region of the nozzle channel 7.

As a result of the direct connection of the sprue nozzle 15, which is exposed to high shear forces, to the cold runner beam 1 in the region of the nozzle duct 7, high shear forces can consequently be transmitted without the risk of leaks.

To further secure this sealing connection, it is provided that an O-ring 16 is arranged on a radial groove on the outer circumference of the sprue nozzle, said O-ring 16 being sealingly supported on the underside of the cold runner beam 1.

The sprue nozzle 15 is surrounded by a cooling jacket 9 on the outer circumference. The cooling jacket 9 is held here easily replaceable on the sprue nozzle 15. For this purpose, it has radial threaded bores 12 distributed around the circumference, in each of which a grub screw 13 is seated, which is supported with its bolt-side end in the region of an assigned annular groove on the outer circumference of the sprue nozzle 15.

In addition, the cooling jacket 9 is sealed on its upper end face with an O-ring 10 on the underside of the cold runner beam 1 and on the front side (front end face) there is again a radial annular groove on the sprue nozzle 15, in which an O-ring 14 sits, which is supported on the associated end face on the front side of the cooling jacket 9.

As a result, the cooling jacket 9 forms large-calibrated ones which extend closely to the front of the nozzle body - 9 -

Cooling channels 11, so that the tip area of the nozzle body 8 can be cooled to a high degree.

It can be seen here that the cooling channels 5 in the cold channel bar 05 have a flow opening directly to the cooling channels 11 arranged in the cooling jacket 9.

A sliding nozzle 21 is arranged on the front of the sprue nozzle 15 and can be displaced in the longitudinal direction

10 is held in the inner bore of the sprue nozzle 15. To prevent it from falling out, the inner bore of the sprue nozzle has a radially inwardly directed shoulder 22, which is located on an associated, radially outwardly directed shoulder of the sliding nozzle

15 21 supports.

At the front of the sliding nozzle 21, an insulating body 23 is interchangeably attached to it. The spray compound is then injected 20 into the associated tool shape via the nozzle openings 24 of the sprue nozzle 15.

For easy replacement of the cooling jacket 9, this has an external hexagon 20 corresponding to the width across flats 25. Likewise, the sprue nozzle 15 can be easily replaced by attaching a tool to an assigned hexagon socket 19 in order to loosen the threaded connection in the area of the threaded bore 18. Drawing legend

1 cold runner beam 26 locking screws

2 runner 27 threaded plug

3 cooling connection pieces

4 "

5 cooling channel 6 sprue channel

7 nozzle channel

8 nozzle bodies

9 cooling jacket

10 O-ring 11 cooling channel

12 threaded hole

13 grub screw

14 O-ring

15 sprue nozzle 16 O-ring

17 threaded shoulder

18 threaded hole

19 external six-channel

20 ' ^• 21 sliding nozzle

22 paragraph

23 insulating body

24 nozzle opening

25 deflection plugs

Claims

- 11-patent claims

1. Cold runner block for the processing of elastomers, by means of which the tempered elastomer is injected into a mold under high pressure over a series of parallel, interchangeable nozzle bodies held by clamping means, characterized in that a cold runner beam (1) in the area of the Nozzle channels (7) have threaded bores (18) and the nozzle bodies (8), which each consist of a sprue nozzle (15) and a cooling jacket (9), have a corresponding threaded attachment (17) with which they enter the nozzles - channels (7) are screwed in.

2. Cold runner block for the processing of elastomers according to claim 1, dadurchgekennzeich¬ net that the cooling jacket (9) has cross holes in which grub screws (13) engage, which engage with their bolt-side ends in an associated annular groove on the outer circumference of the sprue nozzle (15) , wherein the cooling jacket (9) is held in a sealing manner on the one hand on the underside of the cold runner beam (1) and on the other hand on the front of the sprue nozzle (15) via O-rings (10, 14).

3. Cold runner block for processing elastomers according to claim 1, d a d u r c h g e k e n n z e i c h- n e t that the cooling jacket (9) is screwed onto the sprue nozzle (15).

4. Cold runner block for the processing of elastomers according to claim 1, dadurchgekennzeic h- net that the sprue nozzle is a calibrated sliding nozzle (21).