DE10317635B4 - Spray nozzle for injection molding or extrusion machines - Google Patents

Abstract

Spray nozzle for injection molding or Extrusion machines, consisting essentially of a nozzle head (13), by means of a nozzle tube (16) is connectable to the cylinder of the injection molding or extrusion machine and has a central bore passing into an exit bore (23), and a strainer body (12) inserted into the central bore with numerous, fine, radial sieve bores (19), which the Cavity (24) of the screen body (12) with one of sieve body (12) and nozzle head (13) connect a limited annular channel (27), characterized that the screen body (12) on the side of the outlet bore (23) facing a cleaning hole (10), which with an adjustable closure needle (11) lockable is.

Description

The The invention relates to a spray nozzle for injection molding or extrusion machines referred to in the preamble of claim 1 Art. By means of such spray nozzles the molten plastic mass is removed from the cylinder, e.g. a screw cylinder, the injection molding or extrusion in the Injection molding tool introduced. Because the plastic melt that made Granulate, regrind or recycled material is often still Foreign body, e.g. Residues from Metal, paper, glass, wood or similar Contains particles, it is, especially in the production of high quality injection molded parts necessary, the plastic melt before injection into the injection mold by means of a sieve body too clean.

A combined with a sieve body spray nozzle is off DE 29 04 158 C2 known. In this spray nozzle, a strainer body is inserted into the central bore of the nozzle head. This sieve body consists of a cylindrical sieve sleeve whose jacket has numerous, fine radial sieve holes, through which the pressed into the cavity of the sieve body plastic compound is pressed into an annular channel, which is formed by the sieve body and nozzle head. On the side facing the outlet bore of the nozzle head side of the screen body is closed by a conical end wall. Heavy materials contained in the injection molding compound flowing into the screen body collect in the bulge formed by the end wall, so that they can not pass via the screen bores into the annular channel and from here into the injection molding tool.

ever according to the degree of contamination of the plastic melt, the sieve body of To be cleaned periodically to block the screen holes to avoid and thus a constant quality of the injection molded parts to ensure.

in the Operation announces The obstruction of the screen body by a significant increase in pressure in the injection molding machine. In this case, the strainer body removed, cleaned and reinstalled. This is only with a shutdown of the entire expensive production plant possible. Experience is required therefor 30 to 40 minutes. The shutdown of the system leads to significant temperature fluctuations throughout the plant, especially in the screw cylinder of the injection molding machine as well as in the cooled or heated injection mold, resulting in overheating or undercooling of the Plastic melt leads. In order to produce injection-molded parts of consistent quality, must brought the entire system back into thermal equilibrium be, which is time consuming and because of the production interruption very much is expensive.

Of the Present invention is therefore based on the object with the sieve body combined spray nozzle to be designed so that the filter cleaning be carried out without significant interruption can. So should after the set goal, the cleaning without removal of the screen body carried out become.

According to the present Invention becomes the solution this task with a spray nozzle proposed in the preamble of claim 1, the sieve body on the side facing the outlet bore of the nozzle head to be provided with a cleaning hole, which with an adjustable Lockable needle lockable is.

During the production of molded parts, the outlet bore is closed by the closure needle, so that the plastic melt entering the sieve body can only escape through the sieve holes, while foreign bodies contained in the melt remain in the cavity of the sieve body, as described in US Pat DE 29 041 58 C2 is described in detail.

is the foreign body mass in the sieve body so big that the screen holes are clogged in whole or in part, which by an increase in pressure at the injection molding machine can be seen, a cleaning of the screen body is displayed.

To This is the purpose of the screw cylinder of the injection molding machine be separated from the injection mold, whereupon the shutter needle Cleaning hole of the screen body releases to now collect the accumulated in the screen body foreign body to be able to spray with the plastic melt into the open air. These By pressing a button on the machine triggered spray should expediently be repeated two to three times. Following this will be the nozzle reconnected with the injection mold, so that the injection process can be continued.

The Filter cleaning in accordance with the invention designed spray nozzle be carried out within a maximum of one minute, so by cleaning the thermal equilibrium of the plant is not significantly disturbed and the business interruption compared to conventional cleaning operations injection or extruders negligible is.

Structurally, the design of Cleaning bore and valve pin in the screen body according to the invention the known hydraulic or electric needle valve nozzles, in which the outlet bore of the nozzle head is closed, for example, in business interruption with an axially displaceable inside the nozzle head needle.

Preferably is according to claim 2, the cleaning hole of the screen body coaxial with the outlet hole of the nozzle head located, wherein the closure needle coaxial as in the known needle valve for cleaning bore and strainer body is arranged axially displaceable.

The Locking needle can according to claim 3 purely mechanical, or as known hydraulic, pneumatic or be electrically adjustable.

Especially for mechanical Adjustment is the proposal according to claim 4, according to which the closure needle by means of a rotatably mounted in the nozzle tube Exzenters is adjustable. The proposal according to claim 5 serves here the rotation limit of the pivot pin.

at a coaxial arrangement of the valve pin is a centering and floating storage by means of a sogenann th torpedo according to claim 6 in a conventional manner advantageous.

This Torpedo, who both the leadership the shutter needle as well as the determination of the screen body within of the nozzle tube is used and the components against each other seals, is subject to wear and therefore designed as a separate, replaceable component.

To a further proposal according to claims 7 and 8 may be designed according to the invention and arranged shutter needle at the same time the closure of Outlet bore of the nozzle head serve.

To For this purpose, the inventive valve needle has its the cleaning hole associated end opposite to the Cross-section of the valve needle tapered extension, which as a closure for the Outlet bore of the nozzle head serves. In this case, the cleaning hole of the screen body has a larger cross-section as the outlet bore of the nozzle head have, so that the shutter needle in a first position only the outlet bore of the screen body and in a second Position in addition the cleaning hole of the screen body can release.

in this connection it is according to claim 9 expedient, on nozzle tube to provide an adjustable stop which the two mentioned Positions for defines the valve pin.

Of the The invention is based on two exemplary embodiments, which are shown in the drawing, explained in detail.

In show the drawings

1 Axial section of the spray nozzle according to the invention in a schematic representation,

2 Cut longest line II-II in 1

3 Axial section of the complete spray nozzle according to 1 .

4 Cut longest line IV-IV in 3

5 Bottom view of the spray nozzle part in direction V in 4 seen

6 Cut longest line VI-VI in 3 for different rotational position of the pivot pin 14 .

7 Longitudinal section of a spray nozzle according to a second embodiment of the invention

8th Section along the line VIII-VIII in 7 and

9 View of a detail towards IX in 7 seen.

Structure and operation of the spray nozzle according to the invention with filter cleaning can be most easily based on 1 and 2 explain.

In a conventional nozzle head 13 , with its threaded part 13a is screwed into the nozzle tube, not shown, is made of DE 29 041 58 C2 known sieve body 12 set. The sieve body 12 is here with his ring flange 12a set in a corresponding annular shoulder. The cylindrical wall of the sleeve-like screen body 12 is of a variety of radial screen bores 19 interspersed. These sieve bores 19 connect the cylindrical cavity 24 of the screen body 19 with the ring channel 27 , which after insertion of the screen body 12 of this and the inner wall 13b in the nozzle head 13 limited central bore is limited. This central bore extends in the exit direction of the plastic melt via a longitudinal section in the truncated cone-shaped outlet channel into the outlet bore 23 above. The total cross section of the sieve holes 19 of the screen body 12 is larger than the cross section of the outlet hole 23 , so that within the ring channel 27 and the exit channel 13c in the operating state of the machine builds up an overpressure.

The on the side of the exit hole 23 located front wall 12b of the screen body 12 is conical, so that the cavity 24 of the screen body 12 in a conical collecting space 24a empties. The cavity 24 with his collection room 24a traps the foreign bodies contained in the plastic melt, since their cross sections are larger than the cross sections of the sieve holes 19 are.

The front wall 12b has a central cleaning hole 10 on, passing through the front end of the valve pin 11 is closed. The shutter needle 11 is, as symbolized by the double arrow A, displaceable in the axial direction. Is she in 1 right, the cleaning hole is 10 released, leaving the cavity 24 with collection space 24a Trapped foreign particles under the effect of overpressure with the plastic melt through the outlet channel 13c and the exit hole 23 can be hosed.

The axial adjustment of the valve needle 11 serves the pivot pin 14 , at the eccentric 21 the valve pin 11 under the effect of the ring canal 13b and exit channel 13c prevailing overpressure frictionally applied.

In particular 2 makes clear causes a rotation of the pivot pin 14 with his eccentric 21 that the shutter needle 11 in 1 to the right under the effect of the ring channel 27 is pushed back prevailing overpressure, causing the cleaning hole 10 is released.

The pintle 14 has at its laterally projecting end a milled key surface 20 so that it can be operated, for example, with a fork wrench or the like tool. In particular, with automatic control of the pivot pin can be controlled hydraulically, pneumatically or electrically.

Further constructive details emerge from the 3 to 6 with which a full inventively designed spray nozzle is shown in detail.

The nozzle head 13 is with his screen body 12 into the nozzle tube 16 screwed in, which in turn with a nozzle flange 16a is screwed to the injection molding or extrusion machine, not shown.

The valve needle arranged on the symmetry axis of the spray nozzle 11 gets through one into the nozzle tube 16 set torpedo 15 so centered and guided that it is floating axially displaceable.

As already on the basis of 1 and 2 explained, serves for the axial adjustment of the valve pin 11 the pintle 14 which is in the nozzle tube 16 is arranged perpendicular to the axis of symmetry rotatable and the torpedo 15 interspersed. With the five sectional views in 6 are the different positions of the pivot pin 14 illustrates which the transition of the valve pin 11 from the position "up" (left picture in 6 ) to the "To" position (right picture in 6 ) demonstrate.

The diameter of the relative to the pivot pin 14 Off-center eccentric is smaller than the diameter of the pivot pin 14 where the outside of the eccentric 21 with the outside of the pivot pin 14 flees. The height of the eccentric section 21 is slightly larger than the diameter of the valve pin 11 , which creates a secure connection between the valve pin 11 and pintle 14 results.

The pintle 14 passes through the nozzle tube 16 with a tapered pin 14a which is at its outer end by a transverse cylindrical pin 22a is interspersed. Paragraph 14b on the pintle 14 ensures together with the radially protruding cylinder pin 22 for the axial securing of the pivot pin 14 , At the same time serves the cylinder pin 22 with the cylinder pins 25 and 26 the rotation limit of the pivot pin 14 , The serving as a stop cylinder pins 25 and 26 are in a milled area 18 used the nozzle tube.

The inside of the nozzle tube 16 arranged torpedo 15 , which, since it is subject to wear, is designed as a separate replacement part, not only serves the storage and management of the valve pin 11 but lays together with the screwed nozzle head 13 the sieve body 12 firmly. Being in the collection chamber 16b projecting conical projection 15a serves the flow guide for the in the chamber 16b entering plastic melt.

The standing under a high pressure of about 2000 Kp / cm ² plastic melt is by means of a screw, not shown in the drawing of the injection molding machine in the collection chamber 16b pressed and passes over the holes 17 of the torpedo 15 in the cavity 24 of the screen body 12 and from here through the screen holes 19 over the ring channel 27 , the exit channel 13c and the exit hole 23 in the injection molding tool, not shown.

As well as in the cavity 24 of the screen body 12 has collected a sufficiently large amount of foreign bodies, a cleaning of the screen body is necessary. After removal of the spray nozzle of the tool, not shown, in the manner explained above, the shutter needle 11 under the effect of the overpressure in the annular channel 27 back pressed melt, so that between her and the cleaning hole 10 forms a sufficiently large gap through which under the action of the cavity 24 prevailing overpressure the foreign particles can be sprayed with the plastic melt into the open air. This procedure should be repeated two to three times before the valve pin 11 by means of the turning bolt 14 will again go to the "closed" position.

With the 7 to 9 an embodiment of a spray nozzle is shown, in which the invention ago impact is combined with the known features of a hydraulic or electric Nadelverstelldüse.

As in the first embodiment is in the nozzle tube 16 the nozzle head 13 screwed, in the central bore of the screen body 12 is used. After the proposal according to the invention, the cleaning hole 10 by means of a valve pin 11 closable. Unlike the first embodiment, the valve pin 11 at her the exit hole 23 facing end a tapered extension 28 on which at the in 7 left position of the valve pin 11 the exit hole 23 closes.

Will the valve needle 11 as a result of the discharge channel 13c prevailing overpressure pushed back to a middle position, gives the extension 28 the exit hole 23 free, so that plastic melt can be sprayed. Because the shutter needle 11 on the lever in the middle position 30 rests, it still closes the outlet bore 10 so that in the cavity 24 or in the collection chamber 16b Trapped foreign particles can not escape.

Only when the shutter needle 11 in her in 7 pushed back right position arises between the front end of the valve pin 11 and the cleaning hole 10 a sufficiently large annular gap through which the foreign particles through the outlet channel 13c and the exit hole 23 can be hosed.

For closing the valve pin 11 In this embodiment, a lever linkage is provided which consists of a about the axis 31 swiveling lever 30 and one with the lever 30 over the axis 32 pivotally connected control arm 33 exists, which is connected to a hydraulic cylinder, not shown.

The lever 30 is trained as an eccentric stop 29 assigned, which part of a pivot pin 34 is that in terms of design and arrangement of the pivot pin 14 equivalent.

• a) Austrittsbohrung 23 und Reinigungsbohrung 10 verschlossen
• b) Austrittsbohrung 23 geöffnet, Reinigungsbohrung 10 geschlossen
• c) Austrittsbohrung 23 und Reinigungsbohrung 10 geöffnet.

The individual pictures in 9 illustrate the possible positions of the eccentric 29 in which the lever arm 30 the different, in 7 indicated by dashed lines, so that the valve pin 11 alternatively take the following positions:

• a) outlet bore 23 and cleaning hole 10 locked
• b) outlet bore 23 opened, cleaning hole 10 closed
• c) exit hole 23 and cleaning hole 10 open.

The design of the spray nozzle according to this second embodiment makes a minor redesign of the torpedo 15 ' required, like the 7 and 8th reveal.

10

cleaning hole

11

Valve pin

12

screen body

12a

annular flange

12b

bulkhead

13

nozzle head

13a

threaded part

13b

inner wall

13c

outlet channel

14

pintle

14a

spigot

14b

paragraph

15

torpedo

15a

Torpedo lead

16

nozzle tube

16a

nozzle flange

16b

plenum

17

drilling in the torpedo

18

milled surface

19

Siebbohrung

20

key area

21

eccentric

22

straight pin

23

outlet bore

24

cavity

24a

conical collecting space

25

straight pin

26

straight pin

27

annular channel

28

tapered extension

29

Eccentric

30

lever

31

axis

32

axis

33

control arm

Claims (9)

Spray nozzle for injection molding or extrusion machines, essentially consisting of a nozzle head ( 13 ), which by means of a nozzle tube ( 16 ) is connectable to the cylinder of the injection molding or extrusion machine and one in an outlet bore ( 23 ) has a central bore, and a strainer inserted into the central bore ( 12 ) with numerous, fine, radial screen bores ( 19 ), which the cavity ( 24 ) of the screen body ( 12 ) with one of sieve bodies ( 12 ) and nozzle head ( 13 ) limited annular channel ( 27 ), characterized in that the screen body ( 12 ) on the outlet bore ( 23 ) facing side a cleaning hole ( 10 ), which with an adjustable closure needle ( 11 ) is closable. Spray nozzle according to claim 1, characterized in that the cleaning bore ( 10 ) of the screen body ( 12 ) coaxial with the outlet bore ( 23 ) of the nozzle head ( 13 ) and that the valve needle ( 11 ) coaxial with cleaning bore ( 10 ) and sieve bodies ( 12 ) Is arranged axially displaceable. Spray nozzle according to claim 2, characterized in that the closure needle ( 11 ) is mechanically, hydraulically, pneumatically or electrically adjustable. Spray nozzle according to claim 2 or 3, characterized in that the from the cleaning hole ( 10 ) facing away from the end of the needle ( 11 ) on an eccentric ( 21 ) one in the nozzle tube ( 16 ) rotatably mounted, perpendicular to the central axis of the nozzle tube ( 16 ) and valve pin ( 11 ) extending pivot pin ( 14 ) frictionally applied. Spray nozzle according to claim 3 or 4, characterized in that for the rotation limitation of the pivot pin ( 14 ) of this one radially projecting pin ( 22 ), which on the nozzle tube ( 16 ) provided stop pins ( 25 . 26 ) assigned. Spray nozzle according to claim 2 to 5, characterized in that within the nozzle tube ( 16 ) one of axial bores ( 17 ) interspersed Torpedo ( 15 ) is arranged, in which the axially adjustable valve needle ( 11 ) is stored. Spray nozzle according to claim 2 to 6, characterized in that the valve needle ( 11 ) at its the cleaning hole ( 10 ) of the screen body ( 12 ) associated with an end opposite the cross section of the valve needle ( 11 ) tapered extension ( 28 ), which as a closure for the outlet bore ( 23 ) of the nozzle head ( 13 ) serves that the cleaning hole ( 10 ) has a larger cross section than the exit bore ( 23 ) and that the valve needle ( 11 ) in a first position in which the outlet bore ( 23 ) and the cleaning hole is still closed, and in a second position, in which outlet bore ( 23 ) and cleaning hole ( 10 ) are opened, under the action of the outlet channel ( 13c ) or of the annular channel ( 27 ) prevailing overpressure is zurückdrückbar. Spray nozzle according to claim 7, characterized in that the axial adjustment of the valve needle ( 11 ) on the nozzle tube ( 16 ) pivotally mounted lever ( 30 ), at which the valve needle ( 11 ) frictionally rests, and that the pivoting range of the lever ( 30 ) by an adjustable stop ( 29 ) is adjustable. Spray nozzle according to claim 8, characterized in that the adjustable stop of a on the nozzle tube ( 16 ) rotatably mounted pintle ( 34 ), whose eccentric stop ( 29 ) the valve needle ( 11 ) bears frictionally with its rear end, and which extends transversely to the valve needle ( 11 ).